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when galaxies collide

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i'm dr frank summers of the space

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telescope science

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institute and i would like to thank my

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wonderful tech team thomas marufu and

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grant justice

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who are taking this meeting and sending

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it out

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over youtube for you to watch i note

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that we will be online

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only until further notice

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our upcoming talks include in march

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the hubble space telescope from

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cosmological conflict to alien

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atmospheres

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this is tom brown the head of the hubble

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program here at sdsci

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and he's going to give you a wonderful

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wonderful overview

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of what hubble has done over the last 30

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years

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on april 6th uh christopher wanzak an

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author will be here to talk about one of

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his books space fares

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how humans will settle the moon mars

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and beyond in may we have

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a really special treat for you we have

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the consonant collective

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and the bergamot quartet of the peabody

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institute here in baltimore

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this is one of the premier music

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conservatories

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and they will be presenting finding the

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music of the spheres

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hearing stars it will not be just

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lecture it will

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also be a musical performance you're not

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going to want to miss that one

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and if you want to find out keep up with

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all these things

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you go to www.stsci.edu

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public hyphen lectures you'll find this

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webpage

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and on the left you can see you'll find

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links to our webcast

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hitting the subscribe button

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of course you can find out information

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about the upcoming lectures

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and if you click on one of those

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lectures you will get the complete

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details

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including the abstract of the talk and

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after it has been presented

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links to the sdsci webcast as well as

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showed you how to sign up at the website

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subscribe to our youtube channel

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is where we post

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questions you can send them to

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stsci.edu

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we also have social media channels for

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both the hubble space telescope

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the james webb space telescope and for

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the space telescope science institute

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on facebook twitter youtube and

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instagram i myself do a tiny bit of

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social media

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on facebook and twitter as dr frank

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and now the news from the universe for

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february

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the first story tonight it was a dark

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and stormy night

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on neptune now for those of my

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generation

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the phrase it was a dark and stormy

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night is not associated with a novel at

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which it was the very first line

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but it's really associated with snoopy

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and peanuts

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because this is what snoopy uses as his

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first line of his novel

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that he's writing and that's the only

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way anybody in my generation

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actually knew of it i'm told there was a

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book that actually included this as the

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first line

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and in terms of storms we can get some

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really stormy nights here on earth this

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is hurricane isabel and hurricane isabel

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came through baltimore about 15 years

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ago

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and it was quite the stormy night there

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but if you follow astronomy you know

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that

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stormy

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because you want big storms you go to

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jupiter

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big oval up here that's a storm

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that's as large as our entire planet

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and so you have this big orange storm

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here

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and they've actually had observations of

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the great red spot

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for a couple hundred years so it's not

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just a dark and stormy night

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it's a dark and stormy centuries on

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jupiter

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and you can see that these also these

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white ovals are also storms in jupiter

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you get

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red orange ones and red ones and white

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ones

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but neptune neptune actually has storms

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that are dark yes this is what's called

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the great dark spot on neptune

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right it was observed by voyager in 1989

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when the only um the only space mission

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that has flown past the planet neptune

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and so we saw that there is a

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possibility of having these

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giant dark storms on neptune

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unfortunately it's not as long lived as

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the great red spot

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because when hubble looked in 1994

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and this is images of both hemispheres

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of neptune in 1994 from hubble

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the great dark spot was gone so

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these dark storms on neptune form

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and obviously disappear hubble is the

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only telescope that has the keen

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resolution

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to be able to follow these storms and in

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2016 for example

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we saw this dark storm on neptune in its

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southern hemisphere

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and the idea is from computer

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simulations

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that these storms will form at

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mid-latitudes and

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as they migrate toward the equator

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they will dissipate because they're sort

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of supported by something called the

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coriolis force

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you don't really need to understand that

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just know that the coriolis force goes

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away as you get

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to the equator so that they might

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dissipate as they get to the equator

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well

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hubble has covered four dark storms

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since it's been watching

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and the most recent one here it is

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observed in january 2020

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and you can see the large uh dark spot

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here

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and on the right hand side you can see a

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smaller dark spot

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now the large the large dark storm was

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discovered in 2018

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and they followed it as it started to

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move towards the equator

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and presumably would then dissipate away

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but in january 2020 when they looked

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they found

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not only was there a second dark spot

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but also that the storm had reverse

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direction

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and was now heading away from the

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equator this is something that they had

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never seen

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so the question is well first of all why

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did it reverse direction

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and second of all is this second dark

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storm related to the first

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i will tell you that we don't know the

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answer but there is an intriguing

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hypothesis

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computer simulations show that these

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dark storms should actually

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break up every now and then and split

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into multiple storms

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so this could be evidence that this

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storm was

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migrating towards the equator started to

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break up

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spawned off that smaller storm and

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started to reverse direction

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we can't prove that hypothesis but they

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will be studying it

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continuously right as i said hubble is

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the only telescope that can resolve

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these storms and

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follow them so over the 30 years hubble

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has seen

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four dark storms so we really don't have

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a tremendous amount of information to

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work on

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but every time we see one and every new

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data point we get

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tells us more and more about uncovering

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those dark storms

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our second story it's an episode of csi

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smc now when i talk about csi i'm

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talking about

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crime scene investigation this is a

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series of television shows i've actually

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been several television shows they take

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place in

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las vegas and miami and in new york

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well this episode of csi takes place in

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the small magellanic cloud which we

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often refer to as the smc

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right it is a dwarf galaxy it's a

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satellite galaxy of the milky way the

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small magellanic cloud and the large

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magellanic cloud

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that orbits around our milky way galaxy

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and the crime scene here is located in

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the outskirts

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of the snc all right our crime scene is

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called

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supernova remnant 1e0102.2 hyphen 7219

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which is quite the mouthful so we're

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just going to call it

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supernova remnant e0102 that's what

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astronomers call it

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for sure all right and x-rays at the

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crime scene

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revealed that it is the explosive death

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of a star

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a supernova remnant and the remains of

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the star were splattered across

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interstellar space so was it stellar

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suicide

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or was it murder

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all right all right it wasn't murder

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okay it was suicide okay

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supernova explosions are when a star

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blows itself

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apart so we actually understand the

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process of a supernova explosion there's

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no mystery there

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but there are other questions that

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remain

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where and when did the exposure occur

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and can we locate and identify the

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stellar corpse

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to do that they called in a specialist

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named hubble all right hubble

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is known for its high resolution

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measurements that provide

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invaluable forensic evidence

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so this this observation right here is

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from 2003.

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hubble also observed it in 2016.

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and if you look back into the archive

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hubble actually has observations

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spanning about

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20 years of the supernova remnant

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and this supernova remnant is expanding

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and it's an explosion

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at millions of miles an hour so

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looking very carefully they can

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look to see what's happening

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and this is a little movie here we're

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going to go

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into black and white so we can turn it

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and we're going to bounce back and forth

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between epochs and you can see a tiny

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little bit of motion

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okay it's tiny motion but let's zoom in

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and you can see these gas clouds fleeing

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the scene of the crime

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in particular they traced 45 knots of

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ionized oxygen across 19

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00:11:19,190 --> 00:11:15,120
years to determine the 3d structure

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of this expanding nebula the results

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00:11:25,509 --> 00:11:23,040
oops the results are that they

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have a common center of expansion they

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can trace these knots motion

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in 3d back to a common center of

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expansion

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and knowing how fast they're moving they

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00:11:38,389 --> 00:11:35,760
can figure out how long

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00:11:39,670 --> 00:11:38,399
it took and they can pin down the time

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00:11:44,550 --> 00:11:39,680
of the explosion

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00:11:47,670 --> 00:11:44,560
at about 1700 years ago as seen on earth

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00:11:48,150 --> 00:11:47,680
however there's still a problem if you

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00:11:51,990 --> 00:11:48,160
look

307
00:11:55,990 --> 00:11:52,000
carefully at the location it's empty

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00:11:59,670 --> 00:11:56,000
right a supernova should leave behind

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a neutron star or a black hole and these

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00:12:06,389 --> 00:12:03,360
should shine in x-rays

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00:12:08,069 --> 00:12:06,399
but a previously identified x-ray source

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00:12:10,230 --> 00:12:08,079
that's near this

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isn't quite close enough it's a little

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00:12:15,670 --> 00:12:12,079
bit too far away

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in order for the um the uh

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00:12:19,430 --> 00:12:17,760
neutron star or black hole to get a kick

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and move out that far

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00:12:23,430 --> 00:12:21,519
it would have to move at a velocity

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that's just too high for supernova

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00:12:26,150 --> 00:12:24,079
explosions

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00:12:28,389 --> 00:12:26,160
because it's only got 1700 years to move

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00:12:30,870 --> 00:12:28,399
it and they say you know this doesn't

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00:12:33,269 --> 00:12:30,880
fit with the modus operandi of a

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00:12:36,550 --> 00:12:33,279
supernova explosion

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00:12:39,829 --> 00:12:36,560
so while we can't end this episode

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00:12:42,949 --> 00:12:39,839
with a triumphant dano

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we can say stay tuned

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00:12:48,550 --> 00:12:46,079
for the next explosive episode as our

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intrepid astronomical detectives

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00:12:55,990 --> 00:12:51,279
hunt down the stellar corpse of this

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and now we go to our featured speaker

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00:13:04,150 --> 00:13:01,120
for today

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00:13:07,030 --> 00:13:04,160
our speaker today is laura pritchard

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00:13:08,629 --> 00:13:07,040
she is a post-doc at the space telescope

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00:13:09,910 --> 00:13:08,639
science institute she's been there for

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00:13:13,990 --> 00:13:09,920
three years

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00:13:16,069 --> 00:13:14,000
and she came to us courtesy of the uk

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00:13:17,670 --> 00:13:16,079
she did her graduate work at the

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university of oxford

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00:13:21,269 --> 00:13:19,360
and her undergraduate work at the

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00:13:24,230 --> 00:13:21,279
university of leeds

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00:13:26,629 --> 00:13:24,240
and while at the university of belize

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she was on an exchange program

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00:13:30,389 --> 00:13:29,120
where she actually worked with raja guru

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00:13:33,670 --> 00:13:30,399
hatha kurta

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00:13:36,230 --> 00:13:33,680
who is the speaker from la

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00:13:36,870 --> 00:13:36,240
but two from two weeks ago so she got to

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00:13:38,550 --> 00:13:36,880
go to

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00:13:41,030 --> 00:13:38,560
unite uh the university of california

350
00:13:43,670 --> 00:13:41,040
santa cruz and worked there with raja

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00:13:46,069 --> 00:13:43,680
and during that she was extremely lucky

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00:13:49,030 --> 00:13:46,079
raja took her to hawaii to observe

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00:13:50,629 --> 00:13:49,040
uh on keck so she's had quite the

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00:13:52,710 --> 00:13:50,639
experience around it

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00:13:54,790 --> 00:13:52,720
um and i asked her you know what has she

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00:13:56,550 --> 00:13:54,800
been doing in the pandemic and she says

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00:13:57,990 --> 00:13:56,560
well she's been cooking a lot that she

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00:14:00,550 --> 00:13:58,000
really likes to cook and

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00:14:02,150 --> 00:14:00,560
um it's been uh one of her passions and

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00:14:04,949 --> 00:14:02,160
she'd be able to practice a lot

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00:14:05,829 --> 00:14:04,959
and she's also very passionate about

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00:14:08,949 --> 00:14:05,839
hiking

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00:14:09,750 --> 00:14:08,959
so i suggested to her she'd get out to

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00:14:11,670 --> 00:14:09,760
some of the

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00:14:13,269 --> 00:14:11,680
national parks here in the us because

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00:14:14,629 --> 00:14:13,279
honestly there are some of the greatest

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00:14:16,629 --> 00:14:14,639
hiking spots

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00:14:18,389 --> 00:14:16,639
but tonight she will tell you about the

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00:14:20,150 --> 00:14:18,399
milky way versus andromeda

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00:14:22,550 --> 00:14:20,160
when galaxies collide ladies and

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00:14:24,629 --> 00:14:22,560
gentlemen dr laura pritchard

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00:14:26,310 --> 00:14:24,639
hi everyone thank you so much frank and

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00:14:29,110 --> 00:14:26,320
to the other organizers

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00:14:31,189 --> 00:14:29,120
it's a real honor to be giving a space

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00:14:34,470 --> 00:14:31,199
telescope public lecture

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00:14:36,230 --> 00:14:34,480
so thank you all for tuning in

377
00:14:38,470 --> 00:14:36,240
one of the main reasons i wanted to give

378
00:14:39,590 --> 00:14:38,480
this talk is for my family back in the

379
00:14:41,189 --> 00:14:39,600
uk

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00:14:43,110 --> 00:14:41,199
so they've never actually seen me give a

381
00:14:44,790 --> 00:14:43,120
talk on astronomy and as this one is

382
00:14:46,230 --> 00:14:44,800
live streamed it felt like the perfect

383
00:14:47,829 --> 00:14:46,240
opportunity

384
00:14:50,150 --> 00:14:47,839
and as i haven't seen them in over a

385
00:14:51,350 --> 00:14:50,160
year i figured why not now

386
00:14:53,590 --> 00:14:51,360
so i'm very looking forward to getting

387
00:14:55,590 --> 00:14:53,600
my vaccine and hopefully being reunited

388
00:14:58,150 --> 00:14:55,600
with them soon

389
00:14:59,750 --> 00:14:58,160
so i work at the space telescope science

390
00:15:02,389 --> 00:14:59,760
institute and this is based in the

391
00:15:03,990 --> 00:15:02,399
wonderful city of baltimore in maryland

392
00:15:05,670 --> 00:15:04,000
and if you're regulars at this talk

393
00:15:08,069 --> 00:15:05,680
series you're probably very familiar

394
00:15:11,430 --> 00:15:08,079
with space telescope and its work

395
00:15:13,509 --> 00:15:11,440
but some of you may also not be so this

396
00:15:15,430 --> 00:15:13,519
is one of the main reasons i live and

397
00:15:15,910 --> 00:15:15,440
work in baltimore this is the hubble

398
00:15:18,150 --> 00:15:15,920
space

399
00:15:19,110 --> 00:15:18,160
telescope and hubble's science

400
00:15:21,110 --> 00:15:19,120
operations

401
00:15:23,030 --> 00:15:21,120
are based here at the space telescope

402
00:15:25,269 --> 00:15:23,040
science institute

403
00:15:26,470 --> 00:15:25,279
so anytime you see a gorgeous picture of

404
00:15:29,350 --> 00:15:26,480
space it's almost

405
00:15:29,910 --> 00:15:29,360
always from hubble and the main reason

406
00:15:32,389 --> 00:15:29,920
for that

407
00:15:33,350 --> 00:15:32,399
is that hubble is above the earth's

408
00:15:35,189 --> 00:15:33,360
atmosphere

409
00:15:37,430 --> 00:15:35,199
so it doesn't have to look through

410
00:15:38,870 --> 00:15:37,440
clouds it doesn't have to look through

411
00:15:40,230 --> 00:15:38,880
pollution haze

412
00:15:41,910 --> 00:15:40,240
and it doesn't have to look through

413
00:15:43,590 --> 00:15:41,920
turbulence in the earth's atmosphere

414
00:15:45,829 --> 00:15:43,600
this is the same turbulence that you

415
00:15:47,749 --> 00:15:45,839
experience if you're on a plane

416
00:15:49,350 --> 00:15:47,759
so it's these kind of bubbles in the

417
00:15:52,150 --> 00:15:49,360
atmosphere that actually cause

418
00:15:54,710 --> 00:15:52,160
stars to twinkle so if you go above the

419
00:15:57,749 --> 00:15:54,720
earth's atmosphere where hubble is

420
00:15:59,829 --> 00:15:57,759
then you're able to see um

421
00:16:02,069 --> 00:15:59,839
the night sky in a very crisp way and

422
00:16:03,189 --> 00:16:02,079
these stars appear as very steady beams

423
00:16:05,590 --> 00:16:03,199
of light

424
00:16:07,110 --> 00:16:05,600
so hubble is nowhere near baltimore or

425
00:16:10,870 --> 00:16:07,120
any other city as you can see

426
00:16:15,350 --> 00:16:10,880
it's 340 miles above the earth's surface

427
00:16:18,470 --> 00:16:15,360
and it orbits earth every 95 minutes

428
00:16:19,189 --> 00:16:18,480
so one side note here is that thanks to

429
00:16:21,590 --> 00:16:19,199
hubble

430
00:16:23,189 --> 00:16:21,600
images of space look so incredible now

431
00:16:24,069 --> 00:16:23,199
that it can be quite hard to tell the

432
00:16:26,230 --> 00:16:24,079
difference between

433
00:16:27,670 --> 00:16:26,240
an amazing picture from hubble and an

434
00:16:32,710 --> 00:16:27,680
artist's impression

435
00:16:35,749 --> 00:16:32,720
so the reason i say that is because um

436
00:16:37,910 --> 00:16:35,759
basically now that images look so good

437
00:16:40,310 --> 00:16:37,920
when we start to talk about scales of

438
00:16:42,790 --> 00:16:40,320
space it can get confusing

439
00:16:43,509 --> 00:16:42,800
because you may wonder well if that's so

440
00:16:45,030 --> 00:16:43,519
far away

441
00:16:46,870 --> 00:16:45,040
how are we able to get such a good

442
00:16:48,389 --> 00:16:46,880
picture of it when in fact it's just a

443
00:16:51,110 --> 00:16:48,399
beautiful fake image

444
00:16:52,550 --> 00:16:51,120
so in this talk anytime there is an

445
00:16:53,110 --> 00:16:52,560
artist's impression of something in

446
00:16:56,230 --> 00:16:53,120
space

447
00:17:00,710 --> 00:16:56,240
i've just made a small note of that

448
00:17:03,189 --> 00:17:00,720
so i study galaxy evolution

449
00:17:04,069 --> 00:17:03,199
and i use the hubble space telescope to

450
00:17:05,990 --> 00:17:04,079
do this and

451
00:17:07,350 --> 00:17:06,000
other telus and other telescopes on the

452
00:17:09,750 --> 00:17:07,360
ground for this

453
00:17:11,110 --> 00:17:09,760
so in this talk i'm going to go into a

454
00:17:14,150 --> 00:17:11,120
little bit of the history

455
00:17:15,750 --> 00:17:14,160
of how galaxies were discovered i'm then

456
00:17:17,270 --> 00:17:15,760
going to talk about the different types

457
00:17:19,669 --> 00:17:17,280
of galaxies we see

458
00:17:21,590 --> 00:17:19,679
and how those are formed and then i'm

459
00:17:24,549 --> 00:17:21,600
going to go into what will happen

460
00:17:27,750 --> 00:17:24,559
to our galaxy the milky way and what

461
00:17:31,029 --> 00:17:27,760
that will mean for us here on earth

462
00:17:33,430 --> 00:17:31,039
laura hi um do you have youtube

463
00:17:35,190 --> 00:17:33,440
you may be wondering why this isn't so

464
00:17:37,430 --> 00:17:35,200
obviously seen

465
00:17:38,390 --> 00:17:37,440
on a night say for example if you live

466
00:17:40,070 --> 00:17:38,400
in baltimore

467
00:17:41,990 --> 00:17:40,080
well one of the main issues that

468
00:17:42,950 --> 00:17:42,000
prevents us from being able to observe

469
00:17:46,150 --> 00:17:42,960
the night sky

470
00:17:48,710 --> 00:17:46,160
is light so this could be light from

471
00:17:50,470 --> 00:17:48,720
lamps or buildings or it could also be

472
00:17:53,350 --> 00:17:50,480
light from the moon

473
00:17:54,310 --> 00:17:53,360
so in order to get the best glimpse of

474
00:17:56,150 --> 00:17:54,320
the night sky

475
00:17:58,549 --> 00:17:56,160
you need to step away from artificial

476
00:17:59,270 --> 00:17:58,559
light on a clear night when the moon

477
00:18:01,909 --> 00:17:59,280
isn't up

478
00:18:02,870 --> 00:18:01,919
and let your eyes adjust for about 15

479
00:18:04,710 --> 00:18:02,880
minutes

480
00:18:06,230 --> 00:18:04,720
and on those very clear nights you may

481
00:18:08,310 --> 00:18:06,240
be able to catch a glimpse of that

482
00:18:10,870 --> 00:18:08,320
gorgeous band of the milky way running

483
00:18:13,029 --> 00:18:10,880
across the night sky

484
00:18:15,430 --> 00:18:13,039
so here is a clearer picture of the

485
00:18:20,230 --> 00:18:15,440
milky way galaxy

486
00:18:23,350 --> 00:18:20,240
so our galaxy is a spiral disc

487
00:18:25,270 --> 00:18:23,360
and we are in that disc so when we

488
00:18:26,390 --> 00:18:25,280
look out at the rest of our galaxy we

489
00:18:28,549 --> 00:18:26,400
really only see this

490
00:18:29,510 --> 00:18:28,559
thin band of light it's like looking at

491
00:18:32,710 --> 00:18:29,520
a dinner plate

492
00:18:34,310 --> 00:18:32,720
edge on for example our galaxy is made

493
00:18:36,470 --> 00:18:34,320
up of dust and those those

494
00:18:37,750 --> 00:18:36,480
dark lanes running through the middle

495
00:18:40,789 --> 00:18:37,760
made up of stars

496
00:18:42,230 --> 00:18:40,799
and gas and those are all held together

497
00:18:44,950 --> 00:18:42,240
by gravity gravity

498
00:18:45,430 --> 00:18:44,960
is the same force that keeps us on earth

499
00:18:49,110 --> 00:18:45,440
and

500
00:18:51,190 --> 00:18:49,120
the same force that keeps us

501
00:18:52,789 --> 00:18:51,200
in orbit around the sun and the moon in

502
00:18:55,990 --> 00:18:52,799
orbit around us

503
00:18:56,390 --> 00:18:56,000
so this large collection makes up our

504
00:18:59,669 --> 00:18:56,400
home

505
00:19:00,070 --> 00:18:59,679
the milky way so the stars that you can

506
00:19:02,230 --> 00:19:00,080
see

507
00:19:04,789 --> 00:19:02,240
above and below the plane of the galaxy

508
00:19:08,150 --> 00:19:04,799
here those are actually very close to us

509
00:19:09,430 --> 00:19:08,160
in the plane of the galaxy and this glow

510
00:19:10,310 --> 00:19:09,440
of light that you can see in the

511
00:19:12,630 --> 00:19:10,320
background

512
00:19:14,150 --> 00:19:12,640
are actually all of the hundreds of

513
00:19:15,990 --> 00:19:14,160
billions of stars

514
00:19:17,430 --> 00:19:16,000
that make up our galaxy they're just so

515
00:19:19,190 --> 00:19:17,440
far away that they really kind of look

516
00:19:20,549 --> 00:19:19,200
like a fine mist in the background

517
00:19:22,789 --> 00:19:20,559
glowing

518
00:19:23,990 --> 00:19:22,799
you may also spot those kind of red

519
00:19:26,549 --> 00:19:24,000
patches there

520
00:19:27,750 --> 00:19:26,559
those are actually heated clouds of

521
00:19:29,270 --> 00:19:27,760
hydrogen gas

522
00:19:31,270 --> 00:19:29,280
so that's some of the visible gas that

523
00:19:33,510 --> 00:19:31,280
you can see and you may spot

524
00:19:34,549 --> 00:19:33,520
a couple of other interesting objects

525
00:19:36,390 --> 00:19:34,559
and these are the

526
00:19:38,150 --> 00:19:36,400
two bluish blobs down to the bottom

527
00:19:38,549 --> 00:19:38,160
right hand corner and frank has already

528
00:19:40,470 --> 00:19:38,559
actually

529
00:19:42,549 --> 00:19:40,480
introduced one of them so these are the

530
00:19:44,549 --> 00:19:42,559
magellanic clouds

531
00:19:45,750 --> 00:19:44,559
and you may wonder why you haven't seen

532
00:19:46,870 --> 00:19:45,760
these if you live in the northern

533
00:19:48,710 --> 00:19:46,880
hemisphere

534
00:19:49,909 --> 00:19:48,720
these are only visible from the southern

535
00:19:53,190 --> 00:19:49,919
hemisphere

536
00:19:54,950 --> 00:19:53,200
so you'd have to head to australia or

537
00:19:57,190 --> 00:19:54,960
south america or southern africa to

538
00:19:59,510 --> 00:19:57,200
catch a glimpse of the magellanic clouds

539
00:20:00,710 --> 00:19:59,520
and as frank mentioned these are whole

540
00:20:03,750 --> 00:20:00,720
galaxies

541
00:20:05,510 --> 00:20:03,760
that orbit our own galaxy the milky way

542
00:20:07,270 --> 00:20:05,520
and they're spiraling in and will one

543
00:20:10,549 --> 00:20:07,280
day be fully merged

544
00:20:15,590 --> 00:20:13,350
so our understanding of the milky way

545
00:20:18,070 --> 00:20:15,600
galaxies and the universe as a whole

546
00:20:19,430 --> 00:20:18,080
has come a long way in the last few

547
00:20:21,750 --> 00:20:19,440
hundred years

548
00:20:23,830 --> 00:20:21,760
and even huge leaps have been made

549
00:20:26,870 --> 00:20:23,840
within the last century

550
00:20:28,549 --> 00:20:26,880
so in the mid to late 1700s the

551
00:20:29,990 --> 00:20:28,559
herschel's william herschel and his

552
00:20:33,350 --> 00:20:30,000
sister caroline

553
00:20:35,430 --> 00:20:33,360
made a huge effort to survey the heavens

554
00:20:36,950 --> 00:20:35,440
they made vast leaps forward in

555
00:20:39,590 --> 00:20:36,960
telescope design

556
00:20:41,350 --> 00:20:39,600
starting from newton's original design

557
00:20:42,230 --> 00:20:41,360
and then they also recorded everything

558
00:20:43,990 --> 00:20:42,240
they could see

559
00:20:45,430 --> 00:20:44,000
over the course of their lives and this

560
00:20:48,470 --> 00:20:45,440
work was continued

561
00:20:50,310 --> 00:20:48,480
by william's son john caroline really

562
00:20:52,149 --> 00:20:50,320
helped in this effort to develop

563
00:20:55,430 --> 00:20:52,159
the modern mathematical approach that we

564
00:20:59,669 --> 00:20:57,830
and what they noticed in the sky was

565
00:21:02,310 --> 00:20:59,679
that alongside the point-like

566
00:21:02,950 --> 00:21:02,320
stars they also found lots of things

567
00:21:05,830 --> 00:21:02,960
they called

568
00:21:06,390 --> 00:21:05,840
nebulae this is a latin word that means

569
00:21:09,110 --> 00:21:06,400
mist

570
00:21:10,789 --> 00:21:09,120
and it's basically anything that they uh

571
00:21:13,029 --> 00:21:10,799
anything that was not point like

572
00:21:14,310 --> 00:21:13,039
anything that was fuzzy or irregularly

573
00:21:17,430 --> 00:21:14,320
shaped

574
00:21:18,950 --> 00:21:17,440
they called these nebulae and there was

575
00:21:21,110 --> 00:21:18,960
a great debate at the time

576
00:21:23,029 --> 00:21:21,120
over the nature of what these nebulae

577
00:21:24,470 --> 00:21:23,039
were and here's some of their original

578
00:21:27,909 --> 00:21:24,480
sketches of the things that they were

579
00:21:30,870 --> 00:21:27,919
observing through their telescope

580
00:21:31,750 --> 00:21:30,880
so a huge step towards our understanding

581
00:21:34,710 --> 00:21:31,760
of what these

582
00:21:36,950 --> 00:21:34,720
nebulae actually were came from the vast

583
00:21:38,310 --> 00:21:36,960
intellectual leaps of both thomas wright

584
00:21:41,830 --> 00:21:38,320
in 1750

585
00:21:44,070 --> 00:21:41,840
and emmanuel kant in 1755.

586
00:21:45,510 --> 00:21:44,080
so the herschel's wright and kant were

587
00:21:48,390 --> 00:21:45,520
actually all contemporaries

588
00:21:50,310 --> 00:21:48,400
working around the same time so thomas

589
00:21:53,430 --> 00:21:50,320
wright was a british philosopher

590
00:21:56,470 --> 00:21:53,440
and he first proposed that we

591
00:21:58,950 --> 00:21:56,480
are in a massive disk of stars

592
00:22:00,070 --> 00:21:58,960
and that that band of light that you see

593
00:22:02,470 --> 00:22:00,080
in the night sky

594
00:22:03,350 --> 00:22:02,480
is an optical illusion like we were

595
00:22:05,669 --> 00:22:03,360
describing with

596
00:22:06,870 --> 00:22:05,679
the thin plane and we are in that disc

597
00:22:09,510 --> 00:22:06,880
there

598
00:22:10,870 --> 00:22:09,520
he then also proposed that the nebulae

599
00:22:13,510 --> 00:22:10,880
herschel's nebulae

600
00:22:14,390 --> 00:22:13,520
were the same type of thing as our

601
00:22:17,510 --> 00:22:14,400
galaxy

602
00:22:20,070 --> 00:22:17,520
but on a whole uh different plane

603
00:22:21,590 --> 00:22:20,080
so they were termed island universes

604
00:22:23,590 --> 00:22:21,600
because at the time it was thought that

605
00:22:25,029 --> 00:22:23,600
our milky way really was the whole

606
00:22:27,110 --> 00:22:25,039
universe

607
00:22:29,270 --> 00:22:27,120
and so wright proposed that there were

608
00:22:32,549 --> 00:22:29,280
whole other universes

609
00:22:35,669 --> 00:22:32,559
or you know universes these are galaxies

610
00:22:37,029 --> 00:22:35,679
in these other planes and immanuel kant

611
00:22:37,909 --> 00:22:37,039
fully acknowledging wright's

612
00:22:39,830 --> 00:22:37,919
breakthrough

613
00:22:41,870 --> 00:22:39,840
continued this work and developed this

614
00:22:43,430 --> 00:22:41,880
theory and he published his results in

615
00:22:45,669 --> 00:22:43,440
1755.

616
00:22:47,830 --> 00:22:45,679
now this breakthrough is often solely

617
00:22:50,470 --> 00:22:47,840
attributed to emmanuel kant

618
00:22:51,990 --> 00:22:50,480
um and there's no denying he was also a

619
00:22:53,590 --> 00:22:52,000
brilliant philosopher as well he was a

620
00:22:56,710 --> 00:22:53,600
german philosopher

621
00:22:58,789 --> 00:22:56,720
um so these island universes were the

622
00:23:01,110 --> 00:22:58,799
topic of much debate

623
00:23:03,029 --> 00:23:01,120
so there's the theory does that mean

624
00:23:05,669 --> 00:23:03,039
that the case was closed

625
00:23:07,270 --> 00:23:05,679
hardly if at all basically these

626
00:23:07,990 --> 00:23:07,280
theories when they came out at the time

627
00:23:11,029 --> 00:23:08,000
were widely

628
00:23:13,590 --> 00:23:11,039
criticized and discredited

629
00:23:15,590 --> 00:23:13,600
how can you actually prove this theory

630
00:23:18,710 --> 00:23:15,600
if you can't measure the distance

631
00:23:20,830 --> 00:23:18,720
to the nebulae so

632
00:23:22,149 --> 00:23:20,840
this debate was not solved for another

633
00:23:25,590 --> 00:23:22,159
169

634
00:23:29,310 --> 00:23:25,600
years but a key breakthrough

635
00:23:33,110 --> 00:23:29,320
for really resolving this debate came

636
00:23:36,789 --> 00:23:33,120
153 years later in 1908

637
00:23:40,230 --> 00:23:36,799
by the work of henrietta leave it

638
00:23:42,310 --> 00:23:40,240
now to explain um

639
00:23:44,230 --> 00:23:42,320
swan leave it's genius i'm using the

640
00:23:46,149 --> 00:23:44,240
example of a lighthouse

641
00:23:47,830 --> 00:23:46,159
and this lighthouse is a reference to a

642
00:23:49,990 --> 00:23:47,840
trip that i made to nantucket in the

643
00:23:53,909 --> 00:23:50,000
summer of 2019 where i gave a similar

644
00:23:56,149 --> 00:23:53,919
talk so um

645
00:23:57,830 --> 00:23:56,159
my trip to nantucket was to visit the

646
00:24:00,149 --> 00:23:57,840
mariah mitchell observatory

647
00:24:01,510 --> 00:24:00,159
as an affiliated astronomer and if

648
00:24:03,110 --> 00:24:01,520
you've never heard of mariah mitchell

649
00:24:04,549 --> 00:24:03,120
before i would highly recommend

650
00:24:07,029 --> 00:24:04,559
going to read up about her she was a

651
00:24:10,390 --> 00:24:07,039
fascinating woman born in 1818

652
00:24:11,909 --> 00:24:10,400
around the time that william herschel um

653
00:24:14,950 --> 00:24:11,919
around the end of william herschel's

654
00:24:18,310 --> 00:24:14,960
career she was the first professional

655
00:24:20,390 --> 00:24:18,320
women astronomer in america and this was

656
00:24:21,269 --> 00:24:20,400
at a time when even having an education

657
00:24:23,990 --> 00:24:21,279
as a woman

658
00:24:26,310 --> 00:24:24,000
was a rare thing she was also a vocal

659
00:24:27,110 --> 00:24:26,320
opponent to slavery and segregation and

660
00:24:29,269 --> 00:24:27,120
she admitted

661
00:24:30,789 --> 00:24:29,279
non-white students to her school at a

662
00:24:33,110 --> 00:24:30,799
time when

663
00:24:35,590 --> 00:24:33,120
many schools were still segregated and

664
00:24:37,669 --> 00:24:35,600
she also hosted prominent abolitionists

665
00:24:40,470 --> 00:24:37,679
and civil rights activists

666
00:24:42,070 --> 00:24:40,480
who had escaped slavery on nantucket

667
00:24:43,190 --> 00:24:42,080
these were frederick douglass who was

668
00:24:45,669 --> 00:24:43,200
born here in

669
00:24:47,430 --> 00:24:45,679
in maryland and has ties to baltimore

670
00:24:49,669 --> 00:24:47,440
and also sojourner truth

671
00:24:50,549 --> 00:24:49,679
so an interesting slice of history there

672
00:24:53,430 --> 00:24:50,559
so i um

673
00:24:54,710 --> 00:24:53,440
but back to swan leave it and her

674
00:24:57,909 --> 00:24:54,720
breakthrough

675
00:24:59,350 --> 00:24:57,919
so here you can see that this lighthouse

676
00:25:02,390 --> 00:24:59,360
is flashing

677
00:25:03,830 --> 00:25:02,400
so imagine you're on a ship at night you

678
00:25:06,470 --> 00:25:03,840
know that you must be approaching

679
00:25:08,070 --> 00:25:06,480
land soon and you see this bright

680
00:25:09,830 --> 00:25:08,080
fashion flashing light

681
00:25:11,350 --> 00:25:09,840
so you know that that's a lighthouse by

682
00:25:12,870 --> 00:25:11,360
the way that it's flashing

683
00:25:14,789 --> 00:25:12,880
so you know that you must be close to

684
00:25:17,830 --> 00:25:14,799
land

685
00:25:18,950 --> 00:25:17,840
now picture that instead you just see a

686
00:25:21,750 --> 00:25:18,960
very faint

687
00:25:22,870 --> 00:25:21,760
flashing light on the horizon well you

688
00:25:24,470 --> 00:25:22,880
know that that's still

689
00:25:25,990 --> 00:25:24,480
a lighthouse by the way that it's

690
00:25:29,110 --> 00:25:26,000
flashing but because it's so

691
00:25:31,510 --> 00:25:29,120
faint you know that it must be far away

692
00:25:32,630 --> 00:25:31,520
the key bit of information here is that

693
00:25:34,710 --> 00:25:32,640
i know how big

694
00:25:36,070 --> 00:25:34,720
a lighthouse should be if i was standing

695
00:25:38,230 --> 00:25:36,080
right next to it

696
00:25:40,070 --> 00:25:38,240
therefore if it looks very faint then i

697
00:25:40,870 --> 00:25:40,080
can just determine that it's very far

698
00:25:43,350 --> 00:25:40,880
away

699
00:25:46,149 --> 00:25:43,360
we do this automatically all the time if

700
00:25:49,029 --> 00:25:46,159
we recognize something or someone

701
00:25:49,350 --> 00:25:49,039
far away just by how big they appear to

702
00:25:51,510 --> 00:25:49,360
be

703
00:25:53,590 --> 00:25:51,520
our brain automatically calculates how

704
00:25:55,990 --> 00:25:53,600
close they are

705
00:25:57,110 --> 00:25:56,000
so unsurprisingly lighthouses are

706
00:26:00,230 --> 00:25:57,120
relatively

707
00:26:01,430 --> 00:26:00,240
scarce in space but instead henrietta

708
00:26:04,710 --> 00:26:01,440
swan leavitt

709
00:26:06,710 --> 00:26:04,720
used a similar principle in order to

710
00:26:08,950 --> 00:26:06,720
determine distances

711
00:26:10,710 --> 00:26:08,960
during her work as a human computer at

712
00:26:13,590 --> 00:26:10,720
the harvard observatory

713
00:26:14,390 --> 00:26:13,600
she found a relation for this special

714
00:26:17,510 --> 00:26:14,400
type

715
00:26:20,310 --> 00:26:17,520
of variable star she'd found

716
00:26:21,029 --> 00:26:20,320
that by measuring the regularity of the

717
00:26:24,149 --> 00:26:21,039
flashes

718
00:26:27,190 --> 00:26:24,159
much like a lighthouse you could know

719
00:26:29,909 --> 00:26:27,200
how big that star was supposed to be

720
00:26:31,590 --> 00:26:29,919
so if you saw that the star was flashing

721
00:26:31,990 --> 00:26:31,600
you could measure how bright it should

722
00:26:34,230 --> 00:26:32,000
be

723
00:26:36,710 --> 00:26:34,240
so if it looked very faint then you

724
00:26:38,950 --> 00:26:36,720
could tell that it was really far away

725
00:26:40,549 --> 00:26:38,960
and this was her genius discovery in

726
00:26:42,149 --> 00:26:40,559
1908.

727
00:26:45,110 --> 00:26:42,159
in astronomy this is what we call a

728
00:26:46,950 --> 00:26:45,120
standard candle this is a bright source

729
00:26:49,110 --> 00:26:46,960
and we know how bright it should be

730
00:26:52,549 --> 00:26:49,120
therefore we can use that information

731
00:26:55,110 --> 00:26:52,559
to determine distance

732
00:26:58,470 --> 00:26:55,120
so this great debate of the nature of

733
00:27:00,789 --> 00:26:58,480
nebulaes was revived in 1920 between two

734
00:27:02,310 --> 00:27:00,799
prominent astronomers at the time curtis

735
00:27:04,710 --> 00:27:02,320
and shapley

736
00:27:05,510 --> 00:27:04,720
and this debate was resolved by edwin

737
00:27:09,269 --> 00:27:05,520
hubble

738
00:27:12,070 --> 00:27:09,279
in 1924 a full 169

739
00:27:13,750 --> 00:27:12,080
years after writing kant's original

740
00:27:16,390 --> 00:27:13,760
theory

741
00:27:18,230 --> 00:27:16,400
this is less than 100 years ago and it's

742
00:27:21,669 --> 00:27:18,240
amazing to think that even during

743
00:27:24,230 --> 00:27:21,679
world war one humans did not understand

744
00:27:25,830 --> 00:27:24,240
the full extent of the universe

745
00:27:27,669 --> 00:27:25,840
they thought that the milky way was

746
00:27:29,830 --> 00:27:27,679
really all that there was

747
00:27:33,669 --> 00:27:29,840
and they couldn't possibly imagine that

748
00:27:37,430 --> 00:27:33,679
it was vaster than our wildest dreams

749
00:27:39,430 --> 00:27:37,440
so hubble there's no doubt

750
00:27:41,510 --> 00:27:39,440
um discovered some of the most amazing

751
00:27:42,710 --> 00:27:41,520
secrets that unlocked our understanding

752
00:27:44,789 --> 00:27:42,720
of the universe

753
00:27:46,230 --> 00:27:44,799
but by many accounts he was not the

754
00:27:48,310 --> 00:27:46,240
sharpest astronomer

755
00:27:49,269 --> 00:27:48,320
he arrived at the right place at the

756
00:27:50,950 --> 00:27:49,279
right time

757
00:27:53,110 --> 00:27:50,960
and he put in the work to get the

758
00:27:54,789 --> 00:27:53,120
discoveries

759
00:27:56,789 --> 00:27:54,799
hubble arrived to mount wilson

760
00:27:59,510 --> 00:27:56,799
observatory in california

761
00:28:01,269 --> 00:27:59,520
in 1919 and this coincided with the

762
00:28:01,990 --> 00:28:01,279
completion of the 100-inch hooker

763
00:28:03,750 --> 00:28:02,000
telescope

764
00:28:05,430 --> 00:28:03,760
which at the time was the world's

765
00:28:08,470 --> 00:28:05,440
largest

766
00:28:11,830 --> 00:28:08,480
hubble measured was studying the

767
00:28:12,630 --> 00:28:11,840
um great andromeda nebula this is a very

768
00:28:14,630 --> 00:28:12,640
diffuse

769
00:28:15,990 --> 00:28:14,640
fuzzy blob on the sky and it's

770
00:28:18,230 --> 00:28:16,000
incredibly faint so you really

771
00:28:19,750 --> 00:28:18,240
need to go to very good observing

772
00:28:21,510 --> 00:28:19,760
conditions to be able to see this

773
00:28:24,549 --> 00:28:21,520
clearly

774
00:28:25,430 --> 00:28:24,559
and what he was studying in detail um as

775
00:28:27,669 --> 00:28:25,440
he was studying

776
00:28:29,669 --> 00:28:27,679
this galaxy in detail and some of you

777
00:28:32,950 --> 00:28:29,679
may know where this is going

778
00:28:36,070 --> 00:28:32,960
he discovered some of swan leavitt's

779
00:28:39,350 --> 00:28:36,080
variable stars but they were incredibly

780
00:28:42,710 --> 00:28:39,360
faint using the relation

781
00:28:44,470 --> 00:28:42,720
that she found in 1908 hubble was able

782
00:28:46,149 --> 00:28:44,480
to measure the distance to the great

783
00:28:51,669 --> 00:28:46,159
andromeda nebula

784
00:28:55,510 --> 00:28:51,679
of 1.5 million light years

785
00:28:57,029 --> 00:28:55,520
so we know this now as the andromeda

786
00:28:59,669 --> 00:28:57,039
galaxy

787
00:29:00,870 --> 00:28:59,679
this was far beyond the reaches of our

788
00:29:03,669 --> 00:29:00,880
milky way

789
00:29:04,789 --> 00:29:03,679
and it placed it firmly outside to an

790
00:29:06,870 --> 00:29:04,799
island of its own

791
00:29:09,029 --> 00:29:06,880
really confirming writing cancer

792
00:29:12,310 --> 00:29:09,039
theories of these island universes that

793
00:29:13,669 --> 00:29:12,320
we now understand as galaxies

794
00:29:16,950 --> 00:29:13,679
but you'll notice here that it's

795
00:29:18,950 --> 00:29:16,960
actually 2.5 million light years away

796
00:29:20,310 --> 00:29:18,960
um based on the newer information that

797
00:29:21,669 --> 00:29:20,320
we have today and the improved

798
00:29:23,430 --> 00:29:21,679
measurements

799
00:29:25,350 --> 00:29:23,440
and this in astronomy is what we call a

800
00:29:26,230 --> 00:29:25,360
pretty good guess it's around the right

801
00:29:29,590 --> 00:29:26,240
level

802
00:29:31,430 --> 00:29:29,600
um and it was enough to prove this

803
00:29:34,630 --> 00:29:31,440
theory that there were these island

804
00:29:36,630 --> 00:29:34,640
universes these galaxies so

805
00:29:37,669 --> 00:29:36,640
this number is so large that it can

806
00:29:39,110 --> 00:29:37,679
often be quite

807
00:29:41,029 --> 00:29:39,120
hard to wrap your head around what these

808
00:29:43,669 --> 00:29:41,039
numbers really mean in astronomy

809
00:29:45,590 --> 00:29:43,679
but i will try and break down what this

810
00:29:48,389 --> 00:29:45,600
value really means

811
00:29:49,190 --> 00:29:48,399
so the light that we see from andromeda

812
00:29:53,269 --> 00:29:49,200
on earth

813
00:29:53,990 --> 00:29:53,279
is 2.5 million years old it's taken that

814
00:29:57,909 --> 00:29:54,000
long to travel

815
00:30:00,950 --> 00:29:57,919
to us light travels incredibly fast

816
00:30:03,669 --> 00:30:00,960
so fast in fact that on earth it appears

817
00:30:04,549 --> 00:30:03,679
nearly instantaneous but it actually has

818
00:30:08,149 --> 00:30:04,559
a maximum

819
00:30:11,430 --> 00:30:08,159
fixed speed and that's 186

820
00:30:14,549 --> 00:30:11,440
000 miles per second

821
00:30:17,909 --> 00:30:14,559
in a year light can travel

822
00:30:21,110 --> 00:30:17,919
6 trillion miles

823
00:30:24,549 --> 00:30:21,120
that is 6 million million miles and then

824
00:30:26,549 --> 00:30:24,559
andromeda is 2.5 million of those away

825
00:30:27,750 --> 00:30:26,559
so that is a ridiculously large number

826
00:30:30,230 --> 00:30:27,760
and it is really hard to

827
00:30:31,430 --> 00:30:30,240
wrap your head around but even that is

828
00:30:35,510 --> 00:30:31,440
incredibly

829
00:30:37,909 --> 00:30:35,520
close on the scales of the universe

830
00:30:38,950 --> 00:30:37,919
so when hubble was working on this he

831
00:30:41,350 --> 00:30:38,960
was receiving

832
00:30:44,149 --> 00:30:41,360
a lot of backlash for his work and this

833
00:30:47,350 --> 00:30:44,159
was amidst that great debate

834
00:30:49,510 --> 00:30:47,360
so usually astronomers publish their

835
00:30:51,909 --> 00:30:49,520
findings in peer-reviewed articles

836
00:30:53,669 --> 00:30:51,919
present their work to the community and

837
00:30:55,110 --> 00:30:53,679
then that is when the general public

838
00:30:56,470 --> 00:30:55,120
would actually be able to hear about

839
00:30:59,669 --> 00:30:56,480
that information

840
00:31:02,310 --> 00:30:59,679
in the press in part because of the

841
00:31:03,990 --> 00:31:02,320
backlash that hubble was receiving

842
00:31:07,350 --> 00:31:04,000
he went straight to the new york times

843
00:31:09,509 --> 00:31:07,360
with his discovery in november of 1924

844
00:31:11,029 --> 00:31:09,519
he then presented his results to the

845
00:31:12,470 --> 00:31:11,039
astronomical to the american

846
00:31:14,870 --> 00:31:12,480
astronomical society

847
00:31:18,470 --> 00:31:14,880
and the astronomical community on new

848
00:31:22,070 --> 00:31:18,480
year's day in 1925.

849
00:31:25,750 --> 00:31:22,080
so that wasn't all hubble did

850
00:31:28,389 --> 00:31:25,760
he kept measuring distances to galaxies

851
00:31:30,230 --> 00:31:28,399
using using that same method using swan

852
00:31:32,149 --> 00:31:30,240
leavitt's pulsating stars

853
00:31:33,990 --> 00:31:32,159
he could measure the distance to more

854
00:31:37,029 --> 00:31:34,000
distant galaxies

855
00:31:39,269 --> 00:31:37,039
he then also measured their velocities

856
00:31:40,630 --> 00:31:39,279
so this is just speed and also their

857
00:31:42,789 --> 00:31:40,640
direction

858
00:31:44,310 --> 00:31:42,799
we can use light from galaxies to

859
00:31:46,470 --> 00:31:44,320
measure their velocity

860
00:31:48,789 --> 00:31:46,480
and measure if they're moving towards or

861
00:31:52,070 --> 00:31:48,799
away from us

862
00:31:54,149 --> 00:31:52,080
so when galaxies give off light

863
00:31:56,470 --> 00:31:54,159
when that light arrives at earth that's

864
00:31:58,310 --> 00:31:56,480
when we can see that galaxy

865
00:31:59,590 --> 00:31:58,320
and we can capture that light either by

866
00:32:01,750 --> 00:31:59,600
taking an image

867
00:32:04,149 --> 00:32:01,760
like the ones that hubble takes or you

868
00:32:06,070 --> 00:32:04,159
can take something called a spectrum

869
00:32:07,830 --> 00:32:06,080
and this section of spectrum i'm sure

870
00:32:09,590 --> 00:32:07,840
i'm showing this graphic here is just a

871
00:32:11,509 --> 00:32:09,600
very small section of spectrum it's the

872
00:32:14,230 --> 00:32:11,519
rainbow this is the visible spectrum of

873
00:32:16,149 --> 00:32:14,240
light that we that humans can see

874
00:32:17,430 --> 00:32:16,159
different chemical elements have

875
00:32:19,430 --> 00:32:17,440
different features

876
00:32:21,029 --> 00:32:19,440
in a spectrum and so i'm just showing

877
00:32:22,789 --> 00:32:21,039
one example of a feature there which is

878
00:32:25,430 --> 00:32:22,799
just that dark line that you can see in

879
00:32:28,630 --> 00:32:25,440
the top panel

880
00:32:31,590 --> 00:32:28,640
i know where that feature should be

881
00:32:33,269 --> 00:32:31,600
so if a galaxy is moving away from us

882
00:32:34,230 --> 00:32:33,279
that light that we receive from the

883
00:32:37,430 --> 00:32:34,240
galaxy

884
00:32:39,509 --> 00:32:37,440
is actually stretched a little bit

885
00:32:41,430 --> 00:32:39,519
and we know where the features should be

886
00:32:43,190 --> 00:32:41,440
that's that dashed white line

887
00:32:45,430 --> 00:32:43,200
but then we measure where that feature

888
00:32:46,630 --> 00:32:45,440
actually lands and that's that dark line

889
00:32:49,590 --> 00:32:46,640
in the bottom panel

890
00:32:51,750 --> 00:32:49,600
and that that shift will tell us the

891
00:32:54,070 --> 00:32:51,760
speed of the galaxy

892
00:32:55,110 --> 00:32:54,080
now if the if that feature is shifted

893
00:32:57,190 --> 00:32:55,120
towards the red

894
00:32:59,029 --> 00:32:57,200
end of the spectrum this is what we call

895
00:33:00,389 --> 00:32:59,039
a redshift and this means that the

896
00:33:04,870 --> 00:33:00,399
galaxy is moving

897
00:33:07,350 --> 00:33:04,880
away from us so what hubble found

898
00:33:08,230 --> 00:33:07,360
was that far beyond our local

899
00:33:11,509 --> 00:33:08,240
neighborhood

900
00:33:14,549 --> 00:33:11,519
to more distant galaxies the further

901
00:33:17,909 --> 00:33:14,559
a galaxy was was away from us

902
00:33:19,669 --> 00:33:17,919
the faster it was moving

903
00:33:21,750 --> 00:33:19,679
now that is kind of confusing when you

904
00:33:22,230 --> 00:33:21,760
think about it because a lot of hubble's

905
00:33:23,990 --> 00:33:22,240
work

906
00:33:25,269 --> 00:33:24,000
was showing that there's nothing special

907
00:33:28,789 --> 00:33:25,279
about us

908
00:33:30,470 --> 00:33:28,799
our galaxy and earth so then

909
00:33:31,990 --> 00:33:30,480
if there's nothing special about us and

910
00:33:33,909 --> 00:33:32,000
our location

911
00:33:36,830 --> 00:33:33,919
why then is everything moving away from

912
00:33:38,470 --> 00:33:36,840
us how does it know to travel away from

913
00:33:41,430 --> 00:33:38,480
us

914
00:33:42,630 --> 00:33:41,440
and turns out there is nothing special

915
00:33:44,710 --> 00:33:42,640
about our location

916
00:33:45,990 --> 00:33:44,720
this is actually a simple geometric

917
00:33:48,470 --> 00:33:46,000
effect

918
00:33:50,710 --> 00:33:48,480
so here i'm showing a regular grid of

919
00:33:53,430 --> 00:33:50,720
galaxies on the left so imagine you have

920
00:33:55,110 --> 00:33:53,440
this array of galaxies evenly spaced

921
00:33:57,029 --> 00:33:55,120
and this galaxy in the middle here we'll

922
00:33:59,990 --> 00:33:57,039
call the milky way

923
00:34:01,909 --> 00:34:00,000
now imagine you expand that grid by a

924
00:34:02,870 --> 00:34:01,919
small amount and those are the orange

925
00:34:06,789 --> 00:34:02,880
lines that you see

926
00:34:08,790 --> 00:34:06,799
on the right hand side those galaxies

927
00:34:11,030 --> 00:34:08,800
on the orange lines are still evenly

928
00:34:13,669 --> 00:34:11,040
spaced and our milky way

929
00:34:15,510 --> 00:34:13,679
galaxy right in the middle is stayed

930
00:34:18,310 --> 00:34:15,520
stayed pert

931
00:34:19,430 --> 00:34:18,320
but what you can see is that galaxies

932
00:34:21,750 --> 00:34:19,440
are small distance

933
00:34:22,710 --> 00:34:21,760
away from that central galaxy have moved

934
00:34:25,990 --> 00:34:22,720
a little bit

935
00:34:28,389 --> 00:34:26,000
have moved even more

936
00:34:30,149 --> 00:34:28,399
and galaxies towards the edge have moved

937
00:34:32,389 --> 00:34:30,159
even further

938
00:34:33,190 --> 00:34:32,399
so what hubble discovered was that

939
00:34:35,829 --> 00:34:33,200
galaxies

940
00:34:36,230 --> 00:34:35,839
are flying away from us and our milky

941
00:34:41,190 --> 00:34:36,240
way

942
00:34:44,230 --> 00:34:41,200
other galaxies

943
00:34:47,190 --> 00:34:44,240
we have now arrived at another

944
00:34:48,389 --> 00:34:47,200
major breakthrough in astronomy what

945
00:34:53,030 --> 00:34:48,399
hubble found

946
00:34:55,669 --> 00:34:53,040
was that the universe was expanding

947
00:34:56,950 --> 00:34:55,679
and if the universe is expanding then it

948
00:35:00,069 --> 00:34:56,960
must be expanding

949
00:35:03,510 --> 00:35:00,079
from something turns out if you

950
00:35:07,030 --> 00:35:03,520
rewind the motion of all of the galaxies

951
00:35:10,470 --> 00:35:07,040
back by 13.8 billion years

952
00:35:11,270 --> 00:35:10,480
you get to a point an instant after time

953
00:35:14,470 --> 00:35:11,280
began

954
00:35:15,430 --> 00:35:14,480
where everything that we know in the

955
00:35:18,550 --> 00:35:15,440
universe

956
00:35:21,030 --> 00:35:18,560
was at a single point this

957
00:35:23,829 --> 00:35:21,040
is the big bang theory and it was

958
00:35:25,750 --> 00:35:23,839
proposed in 1927

959
00:35:27,109 --> 00:35:25,760
and that was kind of built on previous

960
00:35:28,550 --> 00:35:27,119
work

961
00:35:30,550 --> 00:35:28,560
and it was confirmed with hubble's

962
00:35:33,270 --> 00:35:30,560
findings and the hubble and hubble's law

963
00:35:36,150 --> 00:35:33,280
in 1929

964
00:35:36,950 --> 00:35:36,160
okay so i'm now going to attempt to

965
00:35:39,670 --> 00:35:36,960
answer

966
00:35:41,349 --> 00:35:39,680
three big questions that i get all the

967
00:35:45,030 --> 00:35:41,359
time in astronomy

968
00:35:47,270 --> 00:35:45,040
from non-astronomers but in order to

969
00:35:48,150 --> 00:35:47,280
really accept the answers that i'm about

970
00:35:50,950 --> 00:35:48,160
to give

971
00:35:52,069 --> 00:35:50,960
you need to first really understand the

972
00:35:55,910 --> 00:35:52,079
limitations

973
00:35:56,870 --> 00:35:55,920
of the human brain we humans live on a

974
00:35:59,750 --> 00:35:56,880
tiny planet

975
00:36:01,589 --> 00:35:59,760
and at human size scales therefore we

976
00:36:04,230 --> 00:36:01,599
will never be able to fully

977
00:36:04,950 --> 00:36:04,240
experience all of the physics within the

978
00:36:08,069 --> 00:36:04,960
universe

979
00:36:10,069 --> 00:36:08,079
first hand and we humans like neat

980
00:36:11,670 --> 00:36:10,079
answers we like things that we can

981
00:36:13,589 --> 00:36:11,680
explain

982
00:36:15,589 --> 00:36:13,599
that are satisfying that makes sense to

983
00:36:18,550 --> 00:36:15,599
us in the world around us

984
00:36:20,230 --> 00:36:18,560
but in science and in astronomy the data

985
00:36:20,870 --> 00:36:20,240
don't always give you the answers that

986
00:36:23,109 --> 00:36:20,880
you want

987
00:36:24,470 --> 00:36:23,119
and you have to be able to accept those

988
00:36:26,230 --> 00:36:24,480
answers

989
00:36:27,510 --> 00:36:26,240
so as we go into these following

990
00:36:29,750 --> 00:36:27,520
explanations

991
00:36:31,190 --> 00:36:29,760
first accept the limitations of the

992
00:36:33,589 --> 00:36:31,200
human brain

993
00:36:36,470 --> 00:36:33,599
so the first question i get asked often

994
00:36:39,990 --> 00:36:36,480
is if the universe is expanding

995
00:36:41,829 --> 00:36:40,000
what is it expanding into

996
00:36:44,470 --> 00:36:41,839
and i think this is actually the wrong

997
00:36:48,230 --> 00:36:44,480
way to think about this question

998
00:36:50,950 --> 00:36:48,240
our universe has four dimensions it has

999
00:36:52,710 --> 00:36:50,960
three spatial dimensions we live in a

1000
00:36:55,030 --> 00:36:52,720
three-dimensional universe

1001
00:36:55,990 --> 00:36:55,040
so to get to any single event within our

1002
00:36:57,589 --> 00:36:56,000
universe

1003
00:36:59,589 --> 00:36:57,599
you need to have three spatial

1004
00:37:01,270 --> 00:36:59,599
coordinates that could be longitude

1005
00:37:04,710 --> 00:37:01,280
latitude and altitude

1006
00:37:05,910 --> 00:37:04,720
it could be x y z you need three spatial

1007
00:37:08,150 --> 00:37:05,920
coordinates

1008
00:37:09,510 --> 00:37:08,160
and then i also need to know when an

1009
00:37:11,030 --> 00:37:09,520
event occurred

1010
00:37:14,550 --> 00:37:11,040
therefore i need to know the time that

1011
00:37:17,109 --> 00:37:14,560
it happened that's our fourth dimension

1012
00:37:17,990 --> 00:37:17,119
those dimensions are a property of our

1013
00:37:21,510 --> 00:37:18,000
universe

1014
00:37:25,109 --> 00:37:21,520
also

1015
00:37:25,990 --> 00:37:25,119
making its own space so to think of

1016
00:37:29,270 --> 00:37:26,000
something as

1017
00:37:31,270 --> 00:37:29,280
outside of the universe doesn't actually

1018
00:37:33,990 --> 00:37:31,280
make sense because it's only within the

1019
00:37:36,790 --> 00:37:34,000
universe that space is a thing

1020
00:37:37,430 --> 00:37:36,800
so instead i like to think of it more as

1021
00:37:41,270 --> 00:37:37,440
rapid

1022
00:37:44,710 --> 00:37:41,280
construction it is creating its space

1023
00:37:47,910 --> 00:37:44,720
and as it does everything within it can

1024
00:37:48,710 --> 00:37:47,920
spread out a bit more okay second

1025
00:37:51,510 --> 00:37:48,720
question

1026
00:37:53,589 --> 00:37:51,520
equally unsatisfying answer the next

1027
00:37:56,950 --> 00:37:53,599
question i get asked a lot of the time

1028
00:37:58,390 --> 00:37:56,960
is well if the universe started 13.8

1029
00:38:00,950 --> 00:37:58,400
billion years ago

1030
00:38:02,310 --> 00:38:00,960
what was there before so you'll remember

1031
00:38:03,030 --> 00:38:02,320
that the fourth dimension of the

1032
00:38:06,630 --> 00:38:03,040
universe

1033
00:38:09,829 --> 00:38:06,640
is time without time

1034
00:38:12,630 --> 00:38:09,839
there is no concept of before

1035
00:38:13,910 --> 00:38:12,640
so if you rewind the universe right back

1036
00:38:15,670 --> 00:38:13,920
to the beginning

1037
00:38:17,190 --> 00:38:15,680
there was just the beginning if you

1038
00:38:20,230 --> 00:38:17,200
remove the timeline

1039
00:38:22,150 --> 00:38:20,240
then you remove any notion of before as

1040
00:38:24,950 --> 00:38:22,160
we understand it in our limited

1041
00:38:26,950 --> 00:38:24,960
experiences as humans

1042
00:38:29,109 --> 00:38:26,960
and the third question i often get is

1043
00:38:32,870 --> 00:38:29,119
why why the big bang

1044
00:38:35,270 --> 00:38:32,880
why us and my answer to that is

1045
00:38:36,790 --> 00:38:35,280
that's not actually my job at that point

1046
00:38:40,390 --> 00:38:36,800
i would point you towards

1047
00:38:44,150 --> 00:38:40,400
world religions spirituality philosophy

1048
00:38:44,790 --> 00:38:44,160
and also just acceptance we may never

1049
00:38:46,470 --> 00:38:44,800
know

1050
00:38:48,390 --> 00:38:46,480
and i'm gonna throw it out there we will

1051
00:38:51,109 --> 00:38:48,400
never know

1052
00:38:52,150 --> 00:38:51,119
why we're here but does it really matter

1053
00:38:53,990 --> 00:38:52,160
we exist

1054
00:38:55,589 --> 00:38:54,000
and maybe we can just accept that

1055
00:38:58,310 --> 00:38:55,599
reality and be happy

1056
00:38:59,190 --> 00:38:58,320
but i guess i will leave that up to you

1057
00:39:01,270 --> 00:38:59,200
okay

1058
00:39:03,030 --> 00:39:01,280
so stepping back a little bit from the

1059
00:39:04,870 --> 00:39:03,040
more philosophical journey

1060
00:39:07,109 --> 00:39:04,880
that galaxies can take us on as i know

1061
00:39:10,630 --> 00:39:07,119
it can be a bit of a mind boggle

1062
00:39:14,310 --> 00:39:10,640
um and let's step back into our local

1063
00:39:16,310 --> 00:39:14,320
environment within the universe so here

1064
00:39:18,390 --> 00:39:16,320
i'm going to show you a video which is

1065
00:39:18,870 --> 00:39:18,400
made up of all real data which i really

1066
00:39:21,750 --> 00:39:18,880
like

1067
00:39:22,950 --> 00:39:21,760
um it will be a simulated fly through of

1068
00:39:25,109 --> 00:39:22,960
our local neighborhood

1069
00:39:27,589 --> 00:39:25,119
in the galaxy and then it will it will

1070
00:39:29,589 --> 00:39:27,599
also show you get you situated

1071
00:39:31,510 --> 00:39:29,599
what's surrounding our galaxy and what's

1072
00:39:34,630 --> 00:39:31,520
nearby

1073
00:39:35,990 --> 00:39:34,640
so here we're starting looking at the um

1074
00:39:37,510 --> 00:39:36,000
plane of the milky way and we're

1075
00:39:38,390 --> 00:39:37,520
traveling towards the orion

1076
00:39:39,990 --> 00:39:38,400
constellation

1077
00:39:41,349 --> 00:39:40,000
and you'll notice that the stars within

1078
00:39:43,109 --> 00:39:41,359
orion are actually all different

1079
00:39:43,990 --> 00:39:43,119
distances so that's just a projection

1080
00:39:45,750 --> 00:39:44,000
effect

1081
00:39:47,990 --> 00:39:45,760
and we're traveling here towards the

1082
00:39:50,150 --> 00:39:48,000
orion nebula this is a nursery where

1083
00:39:51,589 --> 00:39:50,160
stars are born

1084
00:39:53,910 --> 00:39:51,599
and you can see that there's another

1085
00:39:56,310 --> 00:39:53,920
nebula in the background

1086
00:39:56,950 --> 00:39:56,320
so these and that has a dense column of

1087
00:39:59,109 --> 00:39:56,960
gas in

1088
00:40:00,950 --> 00:39:59,119
and that's called the horsehead nebula

1089
00:40:05,030 --> 00:40:00,960
so these dense columns of gas

1090
00:40:07,510 --> 00:40:05,040
form stars and we're traveling towards

1091
00:40:09,589 --> 00:40:07,520
a third nebula now this is also a

1092
00:40:10,870 --> 00:40:09,599
nursery for stars but it's a bit more

1093
00:40:13,990 --> 00:40:10,880
evolved this is the

1094
00:40:15,270 --> 00:40:14,000
rosette nebula and all of its stars have

1095
00:40:17,349 --> 00:40:15,280
since blown away

1096
00:40:18,790 --> 00:40:17,359
all the gas and dust and it creates this

1097
00:40:22,150 --> 00:40:18,800
gorgeous hollowing out so

1098
00:40:24,390 --> 00:40:22,160
kind of like a flower effect and then we

1099
00:40:27,030 --> 00:40:24,400
are traveling on to a fourth nebula

1100
00:40:28,309 --> 00:40:27,040
but this is different this like the one

1101
00:40:30,630 --> 00:40:28,319
that frank introduced

1102
00:40:31,589 --> 00:40:30,640
in the beginning is actually the site of

1103
00:40:34,150 --> 00:40:31,599
a supernova

1104
00:40:36,309 --> 00:40:34,160
this is the crab nebula and this

1105
00:40:38,069 --> 00:40:36,319
supernova went off a thousand years ago

1106
00:40:40,870 --> 00:40:38,079
and if you look very closely you can see

1107
00:40:42,870 --> 00:40:40,880
the flashing remnant of the dead star

1108
00:40:44,470 --> 00:40:42,880
so no mystery there we can see that

1109
00:40:47,109 --> 00:40:44,480
pulsar

1110
00:40:47,670 --> 00:40:47,119
so here we are lifting up out of the

1111
00:40:50,390 --> 00:40:47,680
plane

1112
00:40:51,990 --> 00:40:50,400
of the milky way and we will never

1113
00:40:53,910 --> 00:40:52,000
actually make it this far

1114
00:40:56,150 --> 00:40:53,920
in order to take a picture like this so

1115
00:40:57,670 --> 00:40:56,160
you'll see that this galaxy actually

1116
00:40:59,670 --> 00:40:57,680
turns into

1117
00:41:01,270 --> 00:40:59,680
a spiral galaxy this isn't actually our

1118
00:41:03,750 --> 00:41:01,280
milky way but it's what we think

1119
00:41:04,309 --> 00:41:03,760
the galaxy might look a bit like and

1120
00:41:06,630 --> 00:41:04,319
you'll see

1121
00:41:07,750 --> 00:41:06,640
the magellanic clouds again that we saw

1122
00:41:09,910 --> 00:41:07,760
earlier

1123
00:41:12,150 --> 00:41:09,920
and we now zoom out to the local

1124
00:41:13,190 --> 00:41:12,160
environment of our galaxy so we're going

1125
00:41:15,910 --> 00:41:13,200
to spin around

1126
00:41:17,990 --> 00:41:15,920
and you will see our massive neighbor

1127
00:41:20,150 --> 00:41:18,000
the andromeda galaxy

1128
00:41:21,430 --> 00:41:20,160
and our smaller neighbor the triangulum

1129
00:41:24,150 --> 00:41:21,440
galaxy

1130
00:41:24,550 --> 00:41:24,160
and we're going to pass through the um

1131
00:41:26,550 --> 00:41:24,560
disc

1132
00:41:28,710 --> 00:41:26,560
of the triangulum galaxy through one

1133
00:41:31,349 --> 00:41:28,720
another star forming region

1134
00:41:32,470 --> 00:41:31,359
and we know that the andromeda galaxy is

1135
00:41:35,750 --> 00:41:32,480
2.5

1136
00:41:37,750 --> 00:41:35,760
million light years from earth so you'll

1137
00:41:38,870 --> 00:41:37,760
notice there are many points of light in

1138
00:41:42,309 --> 00:41:38,880
the background

1139
00:41:43,829 --> 00:41:42,319
each of these is a whole galaxy

1140
00:41:45,430 --> 00:41:43,839
but you'll notice that these aren't

1141
00:41:48,870 --> 00:41:45,440
evenly distributed

1142
00:41:52,069 --> 00:41:48,880
there's a massive clump of of galaxies

1143
00:41:54,470 --> 00:41:52,079
this is the virgo cluster and

1144
00:41:55,829 --> 00:41:54,480
also you can see that there's massive

1145
00:41:57,349 --> 00:41:55,839
areas of the sky with

1146
00:41:59,030 --> 00:41:57,359
really very little in this is what we

1147
00:42:00,710 --> 00:41:59,040
call voids and then you can see these

1148
00:42:02,470 --> 00:42:00,720
kind of strings of galaxies

1149
00:42:04,069 --> 00:42:02,480
feeding into that cluster and these are

1150
00:42:06,150 --> 00:42:04,079
filaments

1151
00:42:07,190 --> 00:42:06,160
so as we now spin around the virgo

1152
00:42:09,270 --> 00:42:07,200
cluster

1153
00:42:11,109 --> 00:42:09,280
you can see that there are different

1154
00:42:14,470 --> 00:42:11,119
types of galaxies that we can

1155
00:42:15,510 --> 00:42:14,480
observe and as we travel through the

1156
00:42:17,829 --> 00:42:15,520
filament

1157
00:42:18,550 --> 00:42:17,839
in towards the center of the cluster you

1158
00:42:20,470 --> 00:42:18,560
can see

1159
00:42:21,990 --> 00:42:20,480
that a lot of the galaxies in that

1160
00:42:24,550 --> 00:42:22,000
filament in the outskirts

1161
00:42:25,910 --> 00:42:24,560
are spiral disc galaxies much like our

1162
00:42:28,150 --> 00:42:25,920
own and andromeda

1163
00:42:29,510 --> 00:42:28,160
but the closer in we get to the center

1164
00:42:31,510 --> 00:42:29,520
of the virgo cluster

1165
00:42:33,190 --> 00:42:31,520
the galaxies actually start to change a

1166
00:42:36,230 --> 00:42:33,200
bit into more of these

1167
00:42:38,630 --> 00:42:36,240
orbs of stars and we finish here

1168
00:42:39,630 --> 00:42:38,640
on the virgo clusters brightest cluster

1169
00:42:44,950 --> 00:42:39,640
galaxy

1170
00:42:49,910 --> 00:42:44,960
m87 and that name may be familiar to you

1171
00:42:52,950 --> 00:42:49,920
so m87 uh back in april 2019

1172
00:42:56,710 --> 00:42:52,960
the supermassive black hole within

1173
00:42:57,190 --> 00:42:56,720
m87 became the first to be directly

1174
00:43:01,510 --> 00:42:57,200
image

1175
00:43:03,829 --> 00:43:01,520
horizon telescope

1176
00:43:06,390 --> 00:43:03,839
so supermassive black holes and their

1177
00:43:08,230 --> 00:43:06,400
galaxies are a fascinating subject

1178
00:43:10,470 --> 00:43:08,240
i won't be going into more detail here

1179
00:43:13,190 --> 00:43:10,480
but i highly recommend you check out

1180
00:43:14,069 --> 00:43:13,200
my color my colleagues talk dr mitch

1181
00:43:16,790 --> 00:43:14,079
rivolsky

1182
00:43:17,670 --> 00:43:16,800
he gave a talk in the same series back

1183
00:43:19,190 --> 00:43:17,680
in december

1184
00:43:21,990 --> 00:43:19,200
and he'll be going into a lot more

1185
00:43:23,190 --> 00:43:22,000
detail on on the connection between

1186
00:43:25,750 --> 00:43:23,200
galaxies

1187
00:43:27,670 --> 00:43:25,760
and their supermassive black holes i'd

1188
00:43:28,069 --> 00:43:27,680
also like to give another plug for a

1189
00:43:30,550 --> 00:43:28,079
talk

1190
00:43:32,870 --> 00:43:30,560
if you haven't already seen it this was

1191
00:43:36,150 --> 00:43:32,880
a talk by raja gahatakerta

1192
00:43:37,829 --> 00:43:36,160
just a couple of weeks ago and as frank

1193
00:43:39,430 --> 00:43:37,839
mentioned raja was actually a previous

1194
00:43:41,349 --> 00:43:39,440
supervisor for me

1195
00:43:42,550 --> 00:43:41,359
back at the university of california

1196
00:43:44,150 --> 00:43:42,560
santa cruz

1197
00:43:46,550 --> 00:43:44,160
so we worked on a couple of different

1198
00:43:47,270 --> 00:43:46,560
projects one involving stars in the

1199
00:43:49,990 --> 00:43:47,280
milky way

1200
00:43:50,790 --> 00:43:50,000
and another involving stars in andromeda

1201
00:43:53,829 --> 00:43:50,800
and this is really

1202
00:43:55,510 --> 00:43:53,839
raj's expertise so you'll notice given

1203
00:43:57,430 --> 00:43:55,520
the overlap in our interests i'll be

1204
00:44:00,150 --> 00:43:57,440
touching on a couple of similar themes

1205
00:44:01,430 --> 00:44:00,160
to raja but i would definitely recommend

1206
00:44:03,430 --> 00:44:01,440
going to check out raja's

1207
00:44:04,470 --> 00:44:03,440
talk to learn more about our place in

1208
00:44:06,870 --> 00:44:04,480
the cosmos

1209
00:44:08,069 --> 00:44:06,880
black holes gravitational waves and also

1210
00:44:10,550 --> 00:44:08,079
the evolution of the universe

1211
00:44:12,710 --> 00:44:10,560
from those very early stages through to

1212
00:44:15,910 --> 00:44:12,720
where we are today

1213
00:44:18,630 --> 00:44:15,920
so back to classifying galaxies

1214
00:44:19,030 --> 00:44:18,640
so hubble and others spent a lot of time

1215
00:44:20,870 --> 00:44:19,040
looking

1216
00:44:22,950 --> 00:44:20,880
at the different types of galaxies that

1217
00:44:24,790 --> 00:44:22,960
we see in the universe

1218
00:44:25,990 --> 00:44:24,800
and as we saw a little bit in the video

1219
00:44:29,109 --> 00:44:26,000
and that's very clear

1220
00:44:31,030 --> 00:44:29,119
in this image is that you get different

1221
00:44:33,750 --> 00:44:31,040
types of galaxies you get these

1222
00:44:35,109 --> 00:44:33,760
orbs of stars and they tend to be more

1223
00:44:36,950 --> 00:44:35,119
yellow and red

1224
00:44:38,230 --> 00:44:36,960
they're like giant footballs and that

1225
00:44:40,950 --> 00:44:38,240
applies to both us

1226
00:44:41,910 --> 00:44:40,960
and uk football and then in the

1227
00:44:44,710 --> 00:44:41,920
outskirts

1228
00:44:46,150 --> 00:44:44,720
you get to see more spiral galaxies the

1229
00:44:50,150 --> 00:44:46,160
these intricate

1230
00:44:53,349 --> 00:44:50,160
um galaxies like our own milky way

1231
00:44:55,589 --> 00:44:53,359
so i like to think of

1232
00:44:57,589 --> 00:44:55,599
the kind of galaxies towards the center

1233
00:44:57,990 --> 00:44:57,599
of these massive clusters that's kind of

1234
00:45:00,069 --> 00:44:58,000
like

1235
00:45:01,109 --> 00:45:00,079
city living so these are busier

1236
00:45:03,430 --> 00:45:01,119
environments

1237
00:45:04,950 --> 00:45:03,440
they're denser and there tends to be

1238
00:45:07,589 --> 00:45:04,960
more rapid evolution

1239
00:45:09,190 --> 00:45:07,599
compared to the field around dense

1240
00:45:11,589 --> 00:45:09,200
cluster environments

1241
00:45:13,030 --> 00:45:11,599
this is more like country living so

1242
00:45:16,150 --> 00:45:13,040
slower paced

1243
00:45:17,990 --> 00:45:16,160
calmer and slightly slower evolution

1244
00:45:19,910 --> 00:45:18,000
we know that where a human grows up

1245
00:45:22,150 --> 00:45:19,920
affects their evolution

1246
00:45:23,510 --> 00:45:22,160
and the same is true for galaxies where

1247
00:45:26,309 --> 00:45:23,520
a galaxy lives

1248
00:45:27,990 --> 00:45:26,319
i.e how many other galaxies live live

1249
00:45:30,950 --> 00:45:28,000
around it its environment

1250
00:45:31,990 --> 00:45:30,960
affects how you get the different shapes

1251
00:45:35,829 --> 00:45:32,000
and sizes and

1252
00:45:38,630 --> 00:45:35,839
colors so how do you actually

1253
00:45:40,309 --> 00:45:38,640
form these different types of galaxies

1254
00:45:42,470 --> 00:45:40,319
well this is the study of galaxy

1255
00:45:44,790 --> 00:45:42,480
evolution that i work on

1256
00:45:46,790 --> 00:45:44,800
and this is far from solved but we do

1257
00:45:49,750 --> 00:45:46,800
have a few clues

1258
00:45:52,069 --> 00:45:49,760
so first i will go into a couple of very

1259
00:45:54,069 --> 00:45:52,079
simplistic examples of the differences

1260
00:45:55,349 --> 00:45:54,079
between these two types of galaxies that

1261
00:45:57,670 --> 00:45:55,359
we see

1262
00:45:59,109 --> 00:45:57,680
here is a very simplistic model of what

1263
00:46:02,230 --> 00:45:59,119
one of these elliptical

1264
00:46:05,670 --> 00:46:02,240
orbs of stars these elliptical galaxies

1265
00:46:07,910 --> 00:46:05,680
looks like so this is actually a very

1266
00:46:08,950 --> 00:46:07,920
tiny system and you can tell it's small

1267
00:46:12,069 --> 00:46:08,960
because you can actually

1268
00:46:13,349 --> 00:46:12,079
see all of its individual stars now

1269
00:46:15,750 --> 00:46:13,359
broadly speaking

1270
00:46:17,270 --> 00:46:15,760
you can't because of the scales of space

1271
00:46:19,430 --> 00:46:17,280
you can't actually observe

1272
00:46:22,950 --> 00:46:19,440
individual stars in other galaxies

1273
00:46:24,790 --> 00:46:22,960
beyonce the brightest in andromeda

1274
00:46:26,470 --> 00:46:24,800
but this very small system is something

1275
00:46:27,109 --> 00:46:26,480
called a globular cluster and these

1276
00:46:29,670 --> 00:46:27,119
exist

1277
00:46:30,150 --> 00:46:29,680
within spiral galaxies this one is in a

1278
00:46:36,950 --> 00:46:30,160
it

1279
00:46:39,510 --> 00:46:36,960
in such great detail

1280
00:46:41,589 --> 00:46:39,520
but the reason why i pull this example

1281
00:46:43,430 --> 00:46:41,599
up to explain elliptical galaxies is you

1282
00:46:44,069 --> 00:46:43,440
can really clearly see what's happening

1283
00:46:46,790 --> 00:46:44,079
here

1284
00:46:47,670 --> 00:46:46,800
these individual stars are yellow and

1285
00:46:49,910 --> 00:46:47,680
red

1286
00:46:50,870 --> 00:46:49,920
that means they're very small and

1287
00:46:53,589 --> 00:46:50,880
they're old

1288
00:46:54,390 --> 00:46:53,599
and they're cool in astronomy red means

1289
00:46:56,390 --> 00:46:54,400
cool

1290
00:46:57,990 --> 00:46:56,400
so these are long-lived stars they've

1291
00:46:58,470 --> 00:46:58,000
been around for a long time and you can

1292
00:47:00,550 --> 00:46:58,480
see

1293
00:47:01,670 --> 00:47:00,560
there's no dust or gas within this

1294
00:47:04,470 --> 00:47:01,680
system it's

1295
00:47:05,910 --> 00:47:04,480
long since stopped forming stars and

1296
00:47:08,550 --> 00:47:05,920
you're really just left with this kind

1297
00:47:11,589 --> 00:47:08,560
of simple orb of stars

1298
00:47:14,630 --> 00:47:11,599
and here is a very simplistic view

1299
00:47:15,349 --> 00:47:14,640
of what a star from the galaxy a spiral

1300
00:47:17,589 --> 00:47:15,359
galaxy

1301
00:47:18,630 --> 00:47:17,599
might look like so this is not actually

1302
00:47:20,630 --> 00:47:18,640
a galaxy at all

1303
00:47:22,150 --> 00:47:20,640
it's smaller than even the globular

1304
00:47:23,670 --> 00:47:22,160
cluster we were looking at this is just

1305
00:47:26,549 --> 00:47:23,680
one star forming region

1306
00:47:27,030 --> 00:47:26,559
within the magellanic clouds so as you

1307
00:47:29,270 --> 00:47:27,040
can see

1308
00:47:30,150 --> 00:47:29,280
these are very beautiful they contain

1309
00:47:34,309 --> 00:47:30,160
bright

1310
00:47:37,349 --> 00:47:34,319
blue stars really massive stars

1311
00:47:40,710 --> 00:47:37,359
and in astronomy blue is hot

1312
00:47:42,309 --> 00:47:40,720
so these massive stars live fast and die

1313
00:47:44,069 --> 00:47:42,319
young like james dean

1314
00:47:46,309 --> 00:47:44,079
so they die in millions of years

1315
00:47:48,790 --> 00:47:46,319
compared to the billions of years

1316
00:47:49,750 --> 00:47:48,800
of those smaller redder stars and as a

1317
00:47:52,790 --> 00:47:49,760
result

1318
00:47:53,349 --> 00:47:52,800
they're often so close to this the

1319
00:47:55,829 --> 00:47:53,359
parent

1320
00:47:57,910 --> 00:47:55,839
cloud from which they were formed and

1321
00:47:58,950 --> 00:47:57,920
they've heated up that material that you

1322
00:48:01,349 --> 00:47:58,960
can see

1323
00:48:02,549 --> 00:48:01,359
and that gas and dust starts to glow and

1324
00:48:04,630 --> 00:48:02,559
this is what gives

1325
00:48:08,309 --> 00:48:04,640
these amazing colors and makes these

1326
00:48:11,430 --> 00:48:10,790
so how do we get from these very

1327
00:48:13,270 --> 00:48:11,440
intricate

1328
00:48:14,790 --> 00:48:13,280
spiral galaxies with a lot of these

1329
00:48:16,630 --> 00:48:14,800
star-forming galax

1330
00:48:17,990 --> 00:48:16,640
star-forming regions and bright blue

1331
00:48:20,549 --> 00:48:18,000
stars that's what gives them that kind

1332
00:48:21,349 --> 00:48:20,559
of overall blue appearance to these more

1333
00:48:24,950 --> 00:48:21,359
simplistic

1334
00:48:26,630 --> 00:48:24,960
smooth you know old systems that we see

1335
00:48:28,150 --> 00:48:26,640
well the first thing we have to do is

1336
00:48:30,069 --> 00:48:28,160
remove the dust and gas

1337
00:48:31,430 --> 00:48:30,079
in those systems so they can stop

1338
00:48:34,230 --> 00:48:31,440
forming new stars

1339
00:48:36,069 --> 00:48:34,240
and one way to do this is to throw two

1340
00:48:39,190 --> 00:48:36,079
spirals together

1341
00:48:41,589 --> 00:48:39,200
so when two spiral galaxies collide

1342
00:48:43,430 --> 00:48:41,599
you can get a collision with the gas

1343
00:48:45,510 --> 00:48:43,440
this sparks a lot of rapid star

1344
00:48:46,309 --> 00:48:45,520
formation and you can use up that fuel

1345
00:48:49,510 --> 00:48:46,319
very quickly

1346
00:48:52,230 --> 00:48:49,520
in order to form all new stars but then

1347
00:48:53,990 --> 00:48:52,240
but then that's it and also as two

1348
00:48:56,069 --> 00:48:54,000
galaxies collide they will be

1349
00:48:57,750 --> 00:48:56,079
tearing each other apart and material

1350
00:48:58,390 --> 00:48:57,760
will be flung out into space so you can

1351
00:49:01,349 --> 00:48:58,400
expel

1352
00:49:02,150 --> 00:49:01,359
a lot of the material as well so here's

1353
00:49:04,309 --> 00:49:02,160
a simulation

1354
00:49:06,950 --> 00:49:04,319
of just that happening two spiral

1355
00:49:09,510 --> 00:49:06,960
galaxies coming together under gravity

1356
00:49:10,630 --> 00:49:09,520
tearing each other apart and they fall

1357
00:49:13,910 --> 00:49:10,640
together

1358
00:49:16,390 --> 00:49:13,920
to form one system but this takes

1359
00:49:18,069 --> 00:49:16,400
billions of years which is much longer

1360
00:49:19,750 --> 00:49:18,079
than a human lifetime

1361
00:49:21,670 --> 00:49:19,760
how do we actually know that this this

1362
00:49:24,549 --> 00:49:21,680
process occurs

1363
00:49:25,190 --> 00:49:24,559
well there's many examples in space um

1364
00:49:27,030 --> 00:49:25,200
and there's

1365
00:49:28,230 --> 00:49:27,040
fairly damning evidence when you piece

1366
00:49:31,270 --> 00:49:28,240
together all of the

1367
00:49:32,870 --> 00:49:31,280
examples that we have here's just four

1368
00:49:34,790 --> 00:49:32,880
classic examples

1369
00:49:37,510 --> 00:49:34,800
so in space we can see that there are

1370
00:49:39,829 --> 00:49:37,520
spiral galaxies very close to each other

1371
00:49:40,950 --> 00:49:39,839
we then see spiral galaxies start to

1372
00:49:43,030 --> 00:49:40,960
interact

1373
00:49:44,470 --> 00:49:43,040
um but we can still very much tell what

1374
00:49:45,030 --> 00:49:44,480
they are but that they're disturbing

1375
00:49:46,390 --> 00:49:45,040
each other

1376
00:49:47,430 --> 00:49:46,400
and then you have something like in the

1377
00:49:49,430 --> 00:49:47,440
bottom left where they're just

1378
00:49:51,349 --> 00:49:49,440
completely tearing each other apart

1379
00:49:52,470 --> 00:49:51,359
and you can see these sparks of star

1380
00:49:54,549 --> 00:49:52,480
formation

1381
00:49:56,549 --> 00:49:54,559
and then we have the image in the bottom

1382
00:49:58,069 --> 00:49:56,559
right there where you're starting to see

1383
00:50:01,030 --> 00:49:58,079
something a lot like these

1384
00:50:02,230 --> 00:50:01,040
old stellar systems so really just those

1385
00:50:05,270 --> 00:50:02,240
orb like

1386
00:50:07,430 --> 00:50:05,280
yellow red stars but you can still see

1387
00:50:08,790 --> 00:50:07,440
that those spiral arms where the blue

1388
00:50:10,870 --> 00:50:08,800
stars were formed

1389
00:50:13,190 --> 00:50:10,880
you can tell that it was very recently a

1390
00:50:15,349 --> 00:50:13,200
spiral

1391
00:50:16,710 --> 00:50:15,359
so what does this mean for our galaxy

1392
00:50:19,270 --> 00:50:16,720
the milky way

1393
00:50:20,230 --> 00:50:19,280
i told you earlier that the universe is

1394
00:50:24,470 --> 00:50:20,240
expanding

1395
00:50:27,109 --> 00:50:24,480
so why then do galaxies fall together

1396
00:50:28,069 --> 00:50:27,119
so this is just an artist's impression

1397
00:50:29,750 --> 00:50:28,079
of the milky way

1398
00:50:31,910 --> 00:50:29,760
we will never make it this far as we're

1399
00:50:34,950 --> 00:50:31,920
stuck within the disc by gravity

1400
00:50:38,230 --> 00:50:34,960
of of the milky way

1401
00:50:41,589 --> 00:50:38,240
um so the forces that hold together

1402
00:50:44,230 --> 00:50:41,599
the human body are much

1403
00:50:46,710 --> 00:50:44,240
stronger than the pull of the expansion

1404
00:50:50,390 --> 00:50:46,720
of the universe so we as humans are

1405
00:50:52,950 --> 00:50:50,400
aren't expanding also the earth

1406
00:50:55,670 --> 00:50:52,960
stays orbiting the same distance around

1407
00:50:58,069 --> 00:50:55,680
the sun because the forces of gravity

1408
00:50:59,349 --> 00:50:58,079
on the scale of the solar system are

1409
00:51:02,710 --> 00:50:59,359
much stronger

1410
00:51:03,670 --> 00:51:02,720
than the pull of the universe at those

1411
00:51:05,829 --> 00:51:03,680
scales

1412
00:51:08,230 --> 00:51:05,839
and even at larger distances so like we

1413
00:51:10,150 --> 00:51:08,240
saw those large collections of galaxies

1414
00:51:11,750 --> 00:51:10,160
like in the virgo cluster they're all

1415
00:51:13,910 --> 00:51:11,760
held together by gravity

1416
00:51:15,270 --> 00:51:13,920
and that gravity is stronger than the

1417
00:51:17,270 --> 00:51:15,280
pull of the universe

1418
00:51:18,790 --> 00:51:17,280
on those scales so it's all about

1419
00:51:21,430 --> 00:51:18,800
balancing the scales

1420
00:51:21,990 --> 00:51:21,440
at some point the distances between

1421
00:51:25,270 --> 00:51:22,000
objects

1422
00:51:27,109 --> 00:51:25,280
becomes so large that gravity

1423
00:51:29,589 --> 00:51:27,119
doesn't become the dominant force and

1424
00:51:31,990 --> 00:51:29,599
the pull of the universe that expansion

1425
00:51:32,870 --> 00:51:32,000
can take over as the dominant force and

1426
00:51:35,510 --> 00:51:32,880
it's really at those

1427
00:51:36,870 --> 00:51:35,520
large distances that you start to see

1428
00:51:38,950 --> 00:51:36,880
things flying apart

1429
00:51:41,430 --> 00:51:38,960
and this is what hubble measured at

1430
00:51:43,910 --> 00:51:41,440
those great distances

1431
00:51:45,430 --> 00:51:43,920
but in our local neighborhood however

1432
00:51:48,150 --> 00:51:45,440
when you look at our large

1433
00:51:48,549 --> 00:51:48,160
neighbor andromeda we can measure that

1434
00:51:51,990 --> 00:51:48,559
it is

1435
00:51:55,349 --> 00:51:52,000
hurtling towards us at 250

1436
00:51:58,470 --> 00:51:55,359
000 miles per hour the pull of gravity

1437
00:52:00,710 --> 00:51:58,480
is pulling us towards andromeda and we

1438
00:52:02,950 --> 00:52:00,720
are on a direct collision course

1439
00:52:05,109 --> 00:52:02,960
that will start to occur in around 4

1440
00:52:08,230 --> 00:52:05,119
billion years time

1441
00:52:10,150 --> 00:52:08,240
so what will this actually look like so

1442
00:52:13,270 --> 00:52:10,160
here's a simulation of that process

1443
00:52:16,630 --> 00:52:13,280
you can see that the milky way is

1444
00:52:19,109 --> 00:52:16,640
spinning here and as we zoom out we see

1445
00:52:20,950 --> 00:52:19,119
our neighbors in the local group we see

1446
00:52:28,150 --> 00:52:20,960
the andromeda galaxy

1447
00:52:32,790 --> 00:52:30,069
so you can see here andromeda is

1448
00:52:35,430 --> 00:52:32,800
hurtling towards the milky way

1449
00:52:36,710 --> 00:52:35,440
but this is on scales of billions of

1450
00:52:39,829 --> 00:52:36,720
years

1451
00:52:41,510 --> 00:52:39,839
so as the two galaxies begin to interact

1452
00:52:43,829 --> 00:52:41,520
you'll see that they do this dance and

1453
00:52:46,390 --> 00:52:43,839
they start tearing each other apart

1454
00:52:48,150 --> 00:52:46,400
and they come together to form one

1455
00:52:50,470 --> 00:52:48,160
single galaxy

1456
00:52:51,990 --> 00:52:50,480
you'll also notice that the color of the

1457
00:52:54,230 --> 00:52:52,000
galaxy is changing

1458
00:52:55,109 --> 00:52:54,240
so this is using up all that dust and

1459
00:52:56,950 --> 00:52:55,119
gas so these

1460
00:52:58,470 --> 00:52:56,960
young hot blue stars are stopped

1461
00:53:00,710 --> 00:52:58,480
stopping to be formed

1462
00:53:02,390 --> 00:53:00,720
and you're left with the light from the

1463
00:53:04,309 --> 00:53:02,400
red small

1464
00:53:05,670 --> 00:53:04,319
long-lived stars that live for billions

1465
00:53:07,430 --> 00:53:05,680
of years

1466
00:53:09,829 --> 00:53:07,440
and it will just continue to collapse

1467
00:53:13,510 --> 00:53:09,839
down to form a single

1468
00:53:15,750 --> 00:53:13,520
galaxy so what will this amazing process

1469
00:53:16,630 --> 00:53:15,760
actually look like on earth and what

1470
00:53:20,390 --> 00:53:16,640
would it mean

1471
00:53:22,630 --> 00:53:20,400
for us on earth so

1472
00:53:24,549 --> 00:53:22,640
here is the band of the milky way the

1473
00:53:25,750 --> 00:53:24,559
andromeda galaxy and the triangulum

1474
00:53:28,470 --> 00:53:25,760
galaxy

1475
00:53:32,230 --> 00:53:28,480
and you can see that in about 3.75

1476
00:53:33,670 --> 00:53:32,240
billion years we are in for a real treat

1477
00:53:35,829 --> 00:53:33,680
in four billion years when the two

1478
00:53:37,349 --> 00:53:35,839
galaxies begin to interact the sky will

1479
00:53:40,309 --> 00:53:37,359
change dramatically

1480
00:53:42,309 --> 00:53:40,319
and in six billion years the two will

1481
00:53:43,190 --> 00:53:42,319
collapse together to form a single

1482
00:53:45,030 --> 00:53:43,200
galaxy

1483
00:53:47,270 --> 00:53:45,040
with a very comical name that i love

1484
00:53:49,349 --> 00:53:47,280
milk dromeda

1485
00:53:51,349 --> 00:53:49,359
so you can see that this process will

1486
00:53:54,309 --> 00:53:51,359
look amazing from earth

1487
00:53:55,910 --> 00:53:54,319
and it will result in this single galaxy

1488
00:53:57,549 --> 00:53:55,920
the night sky will look incredibly

1489
00:54:01,030 --> 00:53:57,559
different we will have all new

1490
00:54:04,309 --> 00:54:03,829
and this will all occur between the next

1491
00:54:10,390 --> 00:54:04,319
four

1492
00:54:12,790 --> 00:54:10,400
so it's really the gas within these

1493
00:54:13,430 --> 00:54:12,800
galaxy collisions that make them look so

1494
00:54:15,190 --> 00:54:13,440
dramatic

1495
00:54:17,030 --> 00:54:15,200
and this you can see in the andromeda

1496
00:54:18,710 --> 00:54:17,040
galaxy where these two

1497
00:54:21,030 --> 00:54:18,720
sorry in the antennae galaxy as i'm

1498
00:54:22,230 --> 00:54:21,040
showing here when these two galaxies

1499
00:54:24,309 --> 00:54:22,240
come together

1500
00:54:26,390 --> 00:54:24,319
this collision this collision of the gas

1501
00:54:28,069 --> 00:54:26,400
sparks this star formation and it looks

1502
00:54:31,589 --> 00:54:28,079
very dramatic

1503
00:54:35,190 --> 00:54:31,599
but the separation of the stars

1504
00:54:37,510 --> 00:54:35,200
in galaxies is so great that actually

1505
00:54:38,470 --> 00:54:37,520
even in this collision of hundreds of

1506
00:54:42,230 --> 00:54:38,480
billions or even

1507
00:54:45,349 --> 00:54:42,240
trillions of stars it's very unlikely

1508
00:54:47,670 --> 00:54:45,359
that even two stars will interact

1509
00:54:49,349 --> 00:54:47,680
they will likely just sail right past

1510
00:54:52,630 --> 00:54:49,359
each other

1511
00:54:55,270 --> 00:54:52,640
so in order to really grasp the vast

1512
00:54:56,630 --> 00:54:55,280
scales of space let's take a look at

1513
00:55:00,630 --> 00:54:56,640
something more familiar

1514
00:55:04,710 --> 00:55:00,640
let's start with our sun and earth

1515
00:55:06,870 --> 00:55:04,720
so our sun is 4.6 billion years old

1516
00:55:09,190 --> 00:55:06,880
our earth formed soon after that around

1517
00:55:11,829 --> 00:55:09,200
4.5 billion years ago

1518
00:55:13,030 --> 00:55:11,839
and our sun is a very average star it's

1519
00:55:15,270 --> 00:55:13,040
in the middle of its life

1520
00:55:17,589 --> 00:55:15,280
it's very steady it's stable it's one of

1521
00:55:20,630 --> 00:55:17,599
these long-lived ones and it's perfect

1522
00:55:23,910 --> 00:55:20,640
for life we now know

1523
00:55:25,030 --> 00:55:23,920
that most stars have at least one planet

1524
00:55:28,069 --> 00:55:25,040
around them

1525
00:55:29,910 --> 00:55:28,079
so that means of just within our galaxy

1526
00:55:31,990 --> 00:55:29,920
the milky way

1527
00:55:33,190 --> 00:55:32,000
hundreds of the hundreds of billions of

1528
00:55:35,030 --> 00:55:33,200
stars

1529
00:55:36,470 --> 00:55:35,040
most of them will have at least one

1530
00:55:39,349 --> 00:55:36,480
planet

1531
00:55:41,190 --> 00:55:39,359
those numbers are huge so with all of

1532
00:55:43,349 --> 00:55:41,200
those planets out there

1533
00:55:46,069 --> 00:55:43,359
what are the chances that there will be

1534
00:55:49,430 --> 00:55:46,079
intelligent life within our galaxy

1535
00:55:51,349 --> 00:55:49,440
i would say pretty high

1536
00:55:52,950 --> 00:55:51,359
but what are the chances that we will

1537
00:55:56,069 --> 00:55:52,960
actually be able to interact

1538
00:55:59,270 --> 00:55:56,079
with those with any intelligent life

1539
00:56:00,630 --> 00:55:59,280
i would say that's pretty slim and here

1540
00:56:03,990 --> 00:56:00,640
is why

1541
00:56:06,470 --> 00:56:04,000
i think often the concept of earth 2.0

1542
00:56:07,270 --> 00:56:06,480
gets talked about a lot a place that we

1543
00:56:09,990 --> 00:56:07,280
can go to

1544
00:56:11,750 --> 00:56:10,000
when this planet dies and this has

1545
00:56:13,910 --> 00:56:11,760
certainly been the subject of a lot of

1546
00:56:15,990 --> 00:56:13,920
sci-fi films

1547
00:56:17,829 --> 00:56:16,000
and i think it's good to have goals but

1548
00:56:18,950 --> 00:56:17,839
i think it's also good to put this

1549
00:56:22,549 --> 00:56:18,960
particular goal

1550
00:56:24,870 --> 00:56:22,559
in context so let's start with just the

1551
00:56:27,190 --> 00:56:24,880
nearest stars to us

1552
00:56:28,630 --> 00:56:27,200
so our nearest star is a star called

1553
00:56:30,390 --> 00:56:28,640
proxima centauri

1554
00:56:33,750 --> 00:56:30,400
and it's actually just this tiny red

1555
00:56:37,190 --> 00:56:33,760
star just off to the bottom right here

1556
00:56:39,349 --> 00:56:37,200
this very small star is 4.2 light years

1557
00:56:42,230 --> 00:56:39,359
from earth

1558
00:56:44,309 --> 00:56:42,240
it orbits around a double star system

1559
00:56:47,589 --> 00:56:44,319
and their names are alpha centauri

1560
00:56:49,910 --> 00:56:47,599
a and b does a double star system bring

1561
00:56:53,109 --> 00:56:49,920
anything to mind for people

1562
00:56:55,829 --> 00:56:53,119
so this is tatooine from star wars

1563
00:56:56,549 --> 00:56:55,839
and if you live on a planet with a

1564
00:56:58,950 --> 00:56:56,559
doubles

1565
00:57:00,870 --> 00:56:58,960
with in a double star system and that

1566
00:57:02,870 --> 00:57:00,880
actually may be quite common

1567
00:57:05,670 --> 00:57:02,880
you could walk off into a double star

1568
00:57:08,630 --> 00:57:05,680
sunset just like luke skywalker here

1569
00:57:10,789 --> 00:57:08,640
so proxima centauri is the third star in

1570
00:57:13,510 --> 00:57:10,799
this triple star system

1571
00:57:14,870 --> 00:57:13,520
and we know that proxima centauri has a

1572
00:57:18,150 --> 00:57:14,880
planet around it

1573
00:57:20,950 --> 00:57:18,160
so we can just go there well

1574
00:57:21,750 --> 00:57:20,960
rather you than me this is proxima

1575
00:57:24,710 --> 00:57:21,760
centauri

1576
00:57:25,190 --> 00:57:24,720
and it's planet proxima b so a reminder

1577
00:57:28,470 --> 00:57:25,200
that this

1578
00:57:29,829 --> 00:57:28,480
is an artist's impression we have not

1579
00:57:33,109 --> 00:57:29,839
been able to take a picture

1580
00:57:34,789 --> 00:57:33,119
anywhere like this um and we probably

1581
00:57:37,750 --> 00:57:34,799
never will

1582
00:57:39,910 --> 00:57:37,760
so proxima centauri is a very small star

1583
00:57:41,349 --> 00:57:39,920
it's around a tenth of the size of our

1584
00:57:43,990 --> 00:57:41,359
sun

1585
00:57:45,030 --> 00:57:44,000
and it's incredibly unstable because

1586
00:57:47,829 --> 00:57:45,040
it's so small

1587
00:57:49,349 --> 00:57:47,839
it's in a constant battle to produce

1588
00:57:51,510 --> 00:57:49,359
enough radiative energy

1589
00:57:52,870 --> 00:57:51,520
to be able to support its own weight

1590
00:57:55,190 --> 00:57:52,880
under gravity

1591
00:57:57,430 --> 00:57:55,200
so it's constantly fluctuating and as a

1592
00:58:00,870 --> 00:57:57,440
result it regularly produces

1593
00:58:03,750 --> 00:58:00,880
massive flares of dangerous radiation

1594
00:58:04,950 --> 00:58:03,760
and with proxima b being as close as it

1595
00:58:07,109 --> 00:58:04,960
is to the star

1596
00:58:11,270 --> 00:58:07,119
if any life might have lived there in

1597
00:58:13,030 --> 00:58:11,280
the past it's long since been fried

1598
00:58:15,990 --> 00:58:13,040
so we know that this is a highly

1599
00:58:19,270 --> 00:58:16,000
inhospitable planet to humans

1600
00:58:22,069 --> 00:58:19,280
and this is like a hot dusty rock

1601
00:58:22,870 --> 00:58:22,079
so a far cry from our oasis here on

1602
00:58:25,270 --> 00:58:22,880
earth

1603
00:58:27,349 --> 00:58:25,280
i imagine proxima b to be something like

1604
00:58:27,670 --> 00:58:27,359
this scene from mad max with these kind

1605
00:58:30,710 --> 00:58:27,680
of

1606
00:58:34,069 --> 00:58:30,720
massive dust storms that you get

1607
00:58:35,589 --> 00:58:34,079
so you know not ideal but hey just if we

1608
00:58:38,630 --> 00:58:35,599
wanted to go and check it out

1609
00:58:40,390 --> 00:58:38,640
how long would it take to get there so i

1610
00:58:43,349 --> 00:58:40,400
think first it's important to

1611
00:58:44,390 --> 00:58:43,359
figure out how far have we gone so far

1612
00:58:47,270 --> 00:58:44,400
well the furthest

1613
00:58:49,829 --> 00:58:47,280
man-made object from earth is the

1614
00:58:52,309 --> 00:58:49,839
voyager 1 spacecraft this was launched

1615
00:58:54,870 --> 00:58:52,319
in 1977

1616
00:58:55,750 --> 00:58:54,880
and towards the end of its mission it

1617
00:58:58,390 --> 00:58:55,760
turned around

1618
00:59:00,549 --> 00:58:58,400
and took one final image this time of

1619
00:59:02,950 --> 00:59:00,559
earth in 1990

1620
00:59:04,950 --> 00:59:02,960
and this was famously requested by carl

1621
00:59:08,470 --> 00:59:04,960
sagan the astronomer and author

1622
00:59:11,829 --> 00:59:08,480
this is the pale blue dot image

1623
00:59:13,670 --> 00:59:11,839
this image was taken 3.7 billion miles

1624
00:59:16,069 --> 00:59:13,680
from earth

1625
00:59:17,270 --> 00:59:16,079
so that was in 1990 how far have we made

1626
00:59:21,589 --> 00:59:17,280
it so far

1627
00:59:25,150 --> 00:59:21,599
well today voyager 1 is 14.2

1628
00:59:28,230 --> 00:59:25,160
billion miles from earth this is 1

1629
00:59:30,470 --> 00:59:28,240
500th of a light year

1630
00:59:32,789 --> 00:59:30,480
so this is still a long way to go to

1631
00:59:35,430 --> 00:59:32,799
make it just to one light year

1632
00:59:37,109 --> 00:59:35,440
let alone the 4.2 needed to get to

1633
00:59:39,670 --> 00:59:37,119
proxima b

1634
00:59:41,510 --> 00:59:39,680
but you know if we still wanted to go

1635
00:59:43,910 --> 00:59:41,520
ahead with this

1636
00:59:44,710 --> 00:59:43,920
how long would it take to get to proxima

1637
00:59:46,309 --> 00:59:44,720
b

1638
00:59:48,150 --> 00:59:46,319
well we currently don't have the

1639
00:59:50,549 --> 00:59:48,160
technology to get there

1640
00:59:52,789 --> 00:59:50,559
so the first thing we'd need are major

1641
00:59:55,910 --> 00:59:52,799
technological advances

1642
00:59:57,030 --> 00:59:55,920
for both energy generation in the depths

1643
01:00:00,390 --> 00:59:57,040
of space

1644
01:00:03,190 --> 01:00:00,400
and also technology advances to sustain

1645
01:00:04,470 --> 01:00:03,200
human life on a very long interstellar

1646
01:00:08,069 --> 01:00:04,480
journey

1647
01:00:11,430 --> 01:00:08,079
but say for example we very ambitiously

1648
01:00:13,270 --> 01:00:11,440
figured this out in the next 1000 years

1649
01:00:15,190 --> 01:00:13,280
how long could we how long would it take

1650
01:00:17,510 --> 01:00:15,200
to get there well that would depend on

1651
01:00:20,630 --> 01:00:17,520
how fast we traveled

1652
01:00:22,230 --> 01:00:20,640
so what is the fastest thing that humans

1653
01:00:25,190 --> 01:00:22,240
have ever produced

1654
01:00:26,950 --> 01:00:25,200
well this is the fastest man-made object

1655
01:00:30,069 --> 01:00:26,960
this is an amazing mission

1656
01:00:32,630 --> 01:00:30,079
nasa's parker solar probe this was

1657
01:00:33,430 --> 01:00:32,640
launched in 2018 and it's a car-sized

1658
01:00:37,750 --> 01:00:33,440
robot

1659
01:00:41,349 --> 01:00:37,760
that's orbiting the sun and taking data

1660
01:00:44,230 --> 01:00:41,359
on the 21st of january 2021

1661
01:00:44,549 --> 01:00:44,240
so just uh just recently it completed

1662
01:00:48,309 --> 01:00:44,559
its

1663
01:00:52,069 --> 01:00:48,319
seventh orbit of a total of 24 planned

1664
01:00:54,950 --> 01:00:52,079
and it reached a near 290

1665
01:00:56,549 --> 01:00:54,960
000 miles per hour completely smashing

1666
01:00:59,589 --> 01:00:56,559
previous records

1667
01:01:04,150 --> 01:00:59,599
at its peak the parker solar probe

1668
01:01:05,910 --> 01:01:04,160
will reach 430 000 miles per hour

1669
01:01:07,349 --> 01:01:05,920
this is almost double the speed that

1670
01:01:08,789 --> 01:01:07,359
andromeda is moving towards

1671
01:01:11,430 --> 01:01:08,799
us and i think that's absolutely

1672
01:01:14,630 --> 01:01:11,440
incredible it's such a cool mission

1673
01:01:15,670 --> 01:01:14,640
but nasa's parker solar probe doesn't

1674
01:01:18,069 --> 01:01:15,680
need to stop

1675
01:01:19,349 --> 01:01:18,079
it's a death mission it will burn up

1676
01:01:21,750 --> 01:01:19,359
unmanned of course

1677
01:01:22,630 --> 01:01:21,760
it will burn up in the sun's um in the

1678
01:01:24,950 --> 01:01:22,640
sun

1679
01:01:27,190 --> 01:01:24,960
and the hardest thing is slowing down it

1680
01:01:29,030 --> 01:01:27,200
is using the sun's gravity like a

1681
01:01:30,950 --> 01:01:29,040
slingshot to speed up

1682
01:01:32,710 --> 01:01:30,960
but we it would also take the same

1683
01:01:34,309 --> 01:01:32,720
amount of energy to slow down and that's

1684
01:01:34,630 --> 01:01:34,319
something we have not figured out how to

1685
01:01:39,670 --> 01:01:34,640
do

1686
01:01:42,789 --> 01:01:39,680
again in those deep uh areas in space

1687
01:01:45,750 --> 01:01:42,799
but you know in theory if we could get

1688
01:01:48,470 --> 01:01:45,760
a massive spacecraft to move at this

1689
01:01:50,069 --> 01:01:48,480
incredibly ambitious speed

1690
01:01:51,990 --> 01:01:50,079
we'd probably have to go a lot slower

1691
01:01:53,910 --> 01:01:52,000
but you know just saying

1692
01:01:56,470 --> 01:01:53,920
how long would it take to do this

1693
01:01:59,750 --> 01:01:56,480
journey well to get to proxima b

1694
01:02:03,109 --> 01:01:59,760
our closest planet it would take 7

1695
01:02:06,390 --> 01:02:03,119
000 years to travel those 4.2

1696
01:02:07,910 --> 01:02:06,400
light years now if we were traveling at

1697
01:02:10,549 --> 01:02:07,920
the speed of voyager 1

1698
01:02:13,109 --> 01:02:10,559
this journey would actually be over 70

1699
01:02:16,470 --> 01:02:13,119
000 years

1700
01:02:19,430 --> 01:02:16,480
this very optimistic journey length

1701
01:02:20,710 --> 01:02:19,440
that would be about 200 to 300

1702
01:02:24,069 --> 01:02:20,720
generations of

1703
01:02:26,390 --> 01:02:24,079
humans on board one spacecraft

1704
01:02:28,390 --> 01:02:26,400
and even if we wanted to do it unmanned

1705
01:02:30,549 --> 01:02:28,400
that would be an incredibly long time to

1706
01:02:31,990 --> 01:02:30,559
wait for any sort of information

1707
01:02:34,150 --> 01:02:32,000
particularly when we already know this

1708
01:02:37,430 --> 01:02:34,160
planet is inhospitable to life

1709
01:02:38,870 --> 01:02:37,440
and us humans so

1710
01:02:40,710 --> 01:02:38,880
we already know that one's a bit of a

1711
01:02:44,549 --> 01:02:40,720
dud so how about

1712
01:02:47,430 --> 01:02:44,559
we try maybe a more promising star

1713
01:02:47,990 --> 01:02:47,440
well if we take vega for example vega

1714
01:02:50,230 --> 01:02:48,000
appeared

1715
01:02:53,349 --> 01:02:50,240
in carl sagan's book and the film

1716
01:02:55,589 --> 01:02:53,359
contact which is one of my favorites

1717
01:02:56,710 --> 01:02:55,599
using our incredibly ambitious speed it

1718
01:02:59,750 --> 01:02:56,720
would take

1719
01:03:01,349 --> 01:02:59,760
over 40 000 years to reach the start of

1720
01:03:03,589 --> 01:03:01,359
vega

1721
01:03:05,990 --> 01:03:03,599
so you can see that these scales are

1722
01:03:06,950 --> 01:03:06,000
vast in comparison to the length of a

1723
01:03:09,910 --> 01:03:06,960
human life

1724
01:03:13,109 --> 01:03:09,920
so this may not be a viable backup plan

1725
01:03:15,029 --> 01:03:13,119
for the future of humanity

1726
01:03:16,230 --> 01:03:15,039
so even if we just scrap the whole

1727
01:03:18,630 --> 01:03:16,240
travel idea

1728
01:03:20,390 --> 01:03:18,640
and just wanted to send a message that

1729
01:03:21,190 --> 01:03:20,400
message could travel at the speed of

1730
01:03:23,670 --> 01:03:21,200
light

1731
01:03:24,950 --> 01:03:23,680
but even to get a message from one side

1732
01:03:26,950 --> 01:03:24,960
of our galaxy

1733
01:03:29,190 --> 01:03:26,960
to the other side of the galaxy let

1734
01:03:30,069 --> 01:03:29,200
alone all the billions thousands of

1735
01:03:32,870 --> 01:03:30,079
billions of

1736
01:03:33,670 --> 01:03:32,880
galaxies within our universe even just

1737
01:03:36,630 --> 01:03:33,680
to go across

1738
01:03:39,510 --> 01:03:36,640
our galaxy would take a hundred thousand

1739
01:03:41,510 --> 01:03:39,520
years to send that message

1740
01:03:43,670 --> 01:03:41,520
now it's likely that aliens may find us

1741
01:03:46,069 --> 01:03:43,680
at some point

1742
01:03:47,430 --> 01:03:46,079
but if we were to send that message it

1743
01:03:50,549 --> 01:03:47,440
would then take

1744
01:03:53,109 --> 01:03:50,559
that same amount of time to get a reply

1745
01:03:53,910 --> 01:03:53,119
so even if aliens might be listening in

1746
01:03:56,789 --> 01:03:53,920
on us

1747
01:03:57,190 --> 01:03:56,799
given that the first radio signal was

1748
01:04:00,789 --> 01:03:57,200
sent

1749
01:04:02,390 --> 01:04:00,799
in the late 1800s all of the information

1750
01:04:05,109 --> 01:04:02,400
that we have inadvertently

1751
01:04:06,390 --> 01:04:05,119
pumped into space since then all of

1752
01:04:09,190 --> 01:04:06,400
those messages

1753
01:04:10,390 --> 01:04:09,200
have only made it around 100 light years

1754
01:04:12,789 --> 01:04:10,400
or so so still

1755
01:04:15,829 --> 01:04:12,799
only about a thousandth of the distance

1756
01:04:18,069 --> 01:04:15,839
across our galaxy

1757
01:04:20,309 --> 01:04:18,079
i would like to highlight however this

1758
01:04:22,630 --> 01:04:20,319
very new exciting discovery

1759
01:04:23,990 --> 01:04:22,640
by researchers at the university of

1760
01:04:26,230 --> 01:04:24,000
hawaii

1761
01:04:27,990 --> 01:04:26,240
they discovered this planet shown in

1762
01:04:33,430 --> 01:04:28,000
this artist's impression

1763
01:04:35,109 --> 01:04:33,440
toi 561b this planet is 280

1764
01:04:37,029 --> 01:04:35,119
light years from earth so if we were

1765
01:04:40,150 --> 01:04:37,039
using our very ambitious speed

1766
01:04:41,829 --> 01:04:40,160
this would be a mere 440 000 year long

1767
01:04:44,470 --> 01:04:41,839
journey

1768
01:04:45,109 --> 01:04:44,480
this planet is 1.5 times the size of

1769
01:04:47,829 --> 01:04:45,119
earth

1770
01:04:48,390 --> 01:04:47,839
and they found that it has a staggering

1771
01:04:52,069 --> 01:04:48,400
age

1772
01:04:55,270 --> 01:04:52,079
of 10 billion years that's almost

1773
01:04:56,390 --> 01:04:55,280
double earth so when you think about

1774
01:04:59,589 --> 01:04:56,400
that the universe

1775
01:05:01,990 --> 01:04:59,599
is 13.8 billion years old

1776
01:05:03,349 --> 01:05:02,000
our galaxy started forming about 12

1777
01:05:05,750 --> 01:05:03,359
billion years ago

1778
01:05:08,950 --> 01:05:05,760
and this planet started forming pretty

1779
01:05:11,430 --> 01:05:08,960
soon after that while we know

1780
01:05:12,470 --> 01:05:11,440
that this particular planet is an

1781
01:05:15,589 --> 01:05:12,480
inhospitable

1782
01:05:16,390 --> 01:05:15,599
rocky lava ball and it orbits its its

1783
01:05:19,109 --> 01:05:16,400
star

1784
01:05:20,109 --> 01:05:19,119
every 10.5 hours compared to our

1785
01:05:23,190 --> 01:05:20,119
leisurely

1786
01:05:25,029 --> 01:05:23,200
365 days

1787
01:05:26,390 --> 01:05:25,039
it does mean something bigger in the

1788
01:05:29,190 --> 01:05:26,400
context of when

1789
01:05:29,990 --> 01:05:29,200
planets might have formed in this galaxy

1790
01:05:32,630 --> 01:05:30,000
it could

1791
01:05:33,630 --> 01:05:32,640
mean that there were advanced

1792
01:05:36,950 --> 01:05:33,640
intelligent

1793
01:05:40,789 --> 01:05:36,960
civilizations out there billions

1794
01:05:44,150 --> 01:05:40,799
of years ago and just to think how far

1795
01:05:47,349 --> 01:05:44,160
we've come in earth's 4.5 billion years

1796
01:05:49,510 --> 01:05:47,359
from bacteria in the primordial soup

1797
01:05:51,990 --> 01:05:49,520
to conscious beings studying the

1798
01:05:53,990 --> 01:05:52,000
universe with iphones in hand

1799
01:05:55,349 --> 01:05:54,000
it's amazing to think what an extra few

1800
01:05:58,789 --> 01:05:55,359
billion years can mean

1801
01:06:01,270 --> 01:05:58,799
for advanced civilizations

1802
01:06:02,150 --> 01:06:01,280
so while our prospects of interstellar

1803
01:06:04,710 --> 01:06:02,160
travel

1804
01:06:06,549 --> 01:06:04,720
aren't looking so hopeful on any sort of

1805
01:06:10,950 --> 01:06:06,559
reasonable time scale

1806
01:06:13,190 --> 01:06:10,960
given the distances and scales of space

1807
01:06:15,430 --> 01:06:13,200
it's still something we can aim towards

1808
01:06:17,990 --> 01:06:15,440
and put the groundwork in for

1809
01:06:20,150 --> 01:06:18,000
but i don't want us to rely on finding

1810
01:06:22,549 --> 01:06:20,160
an earth 2.0

1811
01:06:23,750 --> 01:06:22,559
when this planet dies but instead to

1812
01:06:26,069 --> 01:06:23,760
really appreciate

1813
01:06:27,349 --> 01:06:26,079
the gorgeous planet that we have that we

1814
01:06:31,109 --> 01:06:27,359
are perfectly

1815
01:06:33,910 --> 01:06:31,119
adapted for already so

1816
01:06:34,950 --> 01:06:33,920
what will happen to earth in four

1817
01:06:37,750 --> 01:06:34,960
billion years

1818
01:06:39,270 --> 01:06:37,760
when andromeda and the milky way begin

1819
01:06:42,710 --> 01:06:39,280
to collide

1820
01:06:45,270 --> 01:06:42,720
well not a whole lot really as we've

1821
01:06:47,510 --> 01:06:45,280
seen the vast distances of space

1822
01:06:48,390 --> 01:06:47,520
stars will most likely just sail right

1823
01:06:51,029 --> 01:06:48,400
past us

1824
01:06:52,150 --> 01:06:51,039
and we will settle in a new galaxy

1825
01:06:54,309 --> 01:06:52,160
mildrometer

1826
01:06:55,910 --> 01:06:54,319
those stars will likely be as far away

1827
01:06:58,390 --> 01:06:55,920
from us as they are now

1828
01:07:00,309 --> 01:06:58,400
which we know is very far there is a

1829
01:07:02,710 --> 01:07:00,319
small chance we could be one of those

1830
01:07:05,750 --> 01:07:02,720
stars that's flung out into space

1831
01:07:07,829 --> 01:07:05,760
but our earth will still stay in orbit

1832
01:07:08,950 --> 01:07:07,839
around the sun the forces of gravity and

1833
01:07:10,710 --> 01:07:08,960
our solar system

1834
01:07:12,069 --> 01:07:10,720
will be able to withstand that and we

1835
01:07:14,549 --> 01:07:12,079
and that would actually be a relatively

1836
01:07:16,470 --> 01:07:14,559
slow process we would just drift off

1837
01:07:18,950 --> 01:07:16,480
into the abyss

1838
01:07:20,950 --> 01:07:18,960
but you may remember that i told you

1839
01:07:25,510 --> 01:07:20,960
that the sun is halfway through

1840
01:07:27,270 --> 01:07:25,520
its lifetime in 5 billion years

1841
01:07:29,349 --> 01:07:27,280
the sun will begin to die so about

1842
01:07:32,630 --> 01:07:29,359
halfway through this collision

1843
01:07:34,470 --> 01:07:32,640
with um andromeda and in five billion

1844
01:07:35,750 --> 01:07:34,480
years the sun will swell up to what we

1845
01:07:38,789 --> 01:07:35,760
call the red giant

1846
01:07:39,430 --> 01:07:38,799
and it will actually engulf the earth so

1847
01:07:41,910 --> 01:07:39,440
while that

1848
01:07:42,870 --> 01:07:41,920
may sound scary this is all a long way

1849
01:07:45,829 --> 01:07:42,880
off in the future

1850
01:07:47,750 --> 01:07:45,839
and we will be long gone if we are

1851
01:07:50,390 --> 01:07:47,760
fortunate to have

1852
01:07:51,670 --> 01:07:50,400
any descendant species they will likely

1853
01:07:54,549 --> 01:07:51,680
be as different from

1854
01:07:57,190 --> 01:07:54,559
us as we are from the bacteria in the

1855
01:08:00,390 --> 01:07:57,200
primordial soup

1856
01:08:02,630 --> 01:08:00,400
so this may sound like doomsday um

1857
01:08:03,750 --> 01:08:02,640
but you know maybe they will figure out

1858
01:08:05,990 --> 01:08:03,760
interstellar travel

1859
01:08:07,829 --> 01:08:06,000
and maybe they will find a new planet

1860
01:08:11,430 --> 01:08:07,839
and who knows what will be waiting for

1861
01:08:14,630 --> 01:08:11,440
them there

1862
01:08:18,149 --> 01:08:14,640
but first we have another major issue

1863
01:08:20,950 --> 01:08:18,159
to attend to i would like to focus

1864
01:08:23,829 --> 01:08:20,960
on the incredible planet that we have

1865
01:08:25,990 --> 01:08:23,839
and to really emphasize the importance

1866
01:08:28,550 --> 01:08:26,000
of addressing our current

1867
01:08:30,630 --> 01:08:28,560
climate and ecological emergent

1868
01:08:33,269 --> 01:08:30,640
emergency that we are in

1869
01:08:34,950 --> 01:08:33,279
this is the biggest threat to human life

1870
01:08:37,829 --> 01:08:34,960
that we face

1871
01:08:38,950 --> 01:08:37,839
if the goal of any life form is to

1872
01:08:41,030 --> 01:08:38,960
survive

1873
01:08:42,390 --> 01:08:41,040
then we are currently working against

1874
01:08:45,110 --> 01:08:42,400
our best interests

1875
01:08:46,229 --> 01:08:45,120
by killing our habitat and that is not a

1876
01:08:47,990 --> 01:08:46,239
great look

1877
01:08:50,070 --> 01:08:48,000
for a species that believes it's the

1878
01:08:53,349 --> 01:08:50,080
most intelligent on earth

1879
01:08:54,950 --> 01:08:53,359
if we continue as we have been future

1880
01:08:58,470 --> 01:08:54,960
generations will never make it

1881
01:09:01,110 --> 01:08:58,480
anywhere near to even the closest star

1882
01:09:02,390 --> 01:09:01,120
we are on a rapid course for

1883
01:09:05,829 --> 01:09:02,400
irreversible

1884
01:09:09,669 --> 01:09:05,839
extensive damage to the earth within my

1885
01:09:12,789 --> 01:09:09,679
lifetime but this catastrophe

1886
01:09:15,829 --> 01:09:12,799
can be avoided the only way

1887
01:09:18,550 --> 01:09:15,839
for human life to survive and give way

1888
01:09:21,110 --> 01:09:18,560
to this next generation of beings

1889
01:09:23,349 --> 01:09:21,120
is to learn to thrive on earth

1890
01:09:25,189 --> 01:09:23,359
sustainably

1891
01:09:26,709 --> 01:09:25,199
i'd like to highlight this recent quote

1892
01:09:29,349 --> 01:09:26,719
by greta timberg and her

1893
01:09:32,390 --> 01:09:29,359
address to the world economic forum you

1894
01:09:35,269 --> 01:09:32,400
can't negotiate with physics

1895
01:09:39,510 --> 01:09:35,279
this is happening it's a dire situation

1896
01:09:42,950 --> 01:09:41,829
the time for discussion is long gone we

1897
01:09:45,189 --> 01:09:42,960
have to take action

1898
01:09:46,630 --> 01:09:45,199
now and i believe it's everyone's

1899
01:09:50,309 --> 01:09:46,640
responsibility

1900
01:09:53,110 --> 01:09:50,319
to contribute to that action

1901
01:09:55,030 --> 01:09:53,120
a very small suggested step that i'd

1902
01:09:57,110 --> 01:09:55,040
like to highlight here is what the earth

1903
01:09:58,390 --> 01:09:57,120
is asking of us in this slide

1904
01:09:59,990 --> 01:09:58,400
and this is to watch david

1905
01:10:02,310 --> 01:10:00,000
attenborough's new documentary on

1906
01:10:05,590 --> 01:10:02,320
netflix a life on our planet

1907
01:10:06,550 --> 01:10:05,600
as a small suggested first step this is

1908
01:10:10,310 --> 01:10:06,560
a great film

1909
01:10:13,830 --> 01:10:10,320
that draws on current science to really

1910
01:10:16,310 --> 01:10:13,840
highlight the urgency of acting now

1911
01:10:18,070 --> 01:10:16,320
but also offers a surprisingly simple

1912
01:10:20,790 --> 01:10:18,080
and hopeful path forward

1913
01:10:22,229 --> 01:10:20,800
for reversing our course towards mass

1914
01:10:24,070 --> 01:10:22,239
extinction

1915
01:10:26,149 --> 01:10:24,080
and i think it's a great first step if

1916
01:10:27,990 --> 01:10:26,159
you haven't already seen it

1917
01:10:30,229 --> 01:10:28,000
we as individuals can often feel

1918
01:10:33,669 --> 01:10:30,239
helpless but if you only take

1919
01:10:36,709 --> 01:10:33,679
one thing from this talk it's that you

1920
01:10:38,630 --> 01:10:36,719
can make a difference by voting in the

1921
01:10:41,669 --> 01:10:38,640
planet's best interests

1922
01:10:43,350 --> 01:10:41,679
by spending investing eating

1923
01:10:44,950 --> 01:10:43,360
and living in the planet's best

1924
01:10:48,550 --> 01:10:44,960
interests you

1925
01:10:50,870 --> 01:10:48,560
can save the future of humanity

1926
01:10:53,189 --> 01:10:50,880
so in the last couple of slides i will

1927
01:10:55,990 --> 01:10:53,199
just bring the focus back to astronomy

1928
01:10:58,070 --> 01:10:56,000
and i'd like to advertise the upcoming

1929
01:11:01,189 --> 01:10:58,080
james webb space telescope

1930
01:11:01,990 --> 01:11:01,199
this is set for launch in october of

1931
01:11:04,550 --> 01:11:02,000
this year

1932
01:11:05,189 --> 01:11:04,560
on halloween actually and hubble's

1933
01:11:07,669 --> 01:11:05,199
flight

1934
01:11:08,709 --> 01:11:07,679
and science operations will be run from

1935
01:11:10,630 --> 01:11:08,719
baltimore

1936
01:11:12,470 --> 01:11:10,640
at the space telescope science institute

1937
01:11:13,430 --> 01:11:12,480
so james webb will have a direct line of

1938
01:11:16,550 --> 01:11:13,440
communication

1939
01:11:18,630 --> 01:11:16,560
with the scientist here in baltimore

1940
01:11:20,470 --> 01:11:18,640
so james webb is really set to

1941
01:11:21,189 --> 01:11:20,480
revolutionize our understanding of the

1942
01:11:24,790 --> 01:11:21,199
universe

1943
01:11:26,550 --> 01:11:24,800
from from planets through to those very

1944
01:11:29,270 --> 01:11:26,560
early stages in a big bang

1945
01:11:30,390 --> 01:11:29,280
and also how galaxies formed we'll be

1946
01:11:32,550 --> 01:11:30,400
able to fill in

1947
01:11:35,270 --> 01:11:32,560
so many gaps that we currently don't uh

1948
01:11:38,950 --> 01:11:35,280
don't know the answers for

1949
01:11:40,070 --> 01:11:38,960
um james webb will have a large 21 foot

1950
01:11:41,750 --> 01:11:40,080
wide mirror

1951
01:11:44,470 --> 01:11:41,760
and it will also be an infrared

1952
01:11:44,950 --> 01:11:44,480
telescope now the sun is actually a very

1953
01:11:48,070 --> 01:11:44,960
bright

1954
01:11:48,870 --> 01:11:48,080
infrared source and so hubble so web

1955
01:11:50,790 --> 01:11:48,880
will actually be

1956
01:11:51,910 --> 01:11:50,800
always facing away from the sun with

1957
01:11:53,590 --> 01:11:51,920
these giant

1958
01:11:55,350 --> 01:11:53,600
sun shields these are about the size of

1959
01:11:59,270 --> 01:11:55,360
a tennis court

1960
01:12:01,350 --> 01:11:59,280
and unlike hubble that orbits the earth

1961
01:12:02,470 --> 01:12:01,360
james webb will actually be orbiting the

1962
01:12:06,470 --> 01:12:02,480
sun

1963
01:12:08,390 --> 01:12:06,480
the same speed as earth so kind of

1964
01:12:10,229 --> 01:12:08,400
constantly in its shadow

1965
01:12:12,229 --> 01:12:10,239
so you can see here in this artist's

1966
01:12:13,910 --> 01:12:12,239
impression at the bottom left-hand

1967
01:12:16,149 --> 01:12:13,920
corner you can see the very small

1968
01:12:17,270 --> 01:12:16,159
earth and with the moon orbiting and

1969
01:12:20,630 --> 01:12:17,280
then the sun off

1970
01:12:24,390 --> 01:12:20,640
to the distance a little bit further so

1971
01:12:26,790 --> 01:12:24,400
why infrared well here's an example

1972
01:12:28,790 --> 01:12:26,800
of the benefits of using a different

1973
01:12:30,149 --> 01:12:28,800
wavelength of light so these are two

1974
01:12:32,310 --> 01:12:30,159
images from hubble

1975
01:12:34,709 --> 01:12:32,320
both in the optical on the left and in

1976
01:12:37,030 --> 01:12:34,719
the near infrared on the right

1977
01:12:38,470 --> 01:12:37,040
and this is of the pillars of creation

1978
01:12:41,669 --> 01:12:38,480
stellar nurseries

1979
01:12:43,590 --> 01:12:41,679
within the eagle nebula so on the left

1980
01:12:45,350 --> 01:12:43,600
you can see the dust and gas from where

1981
01:12:47,110 --> 01:12:45,360
the stars are formed but it's actually

1982
01:12:49,110 --> 01:12:47,120
obscuring a lot of the light

1983
01:12:50,390 --> 01:12:49,120
and when we look at the infrared we can

1984
01:12:54,070 --> 01:12:50,400
pierce through

1985
01:12:57,510 --> 01:12:54,080
those um dark shields in order to reveal

1986
01:12:59,110 --> 01:12:57,520
new exciting physics so james webb will

1987
01:13:00,310 --> 01:12:59,120
actually be in the infrared to much

1988
01:13:03,189 --> 01:13:00,320
further wavelengths

1989
01:13:04,870 --> 01:13:03,199
than hubble can go and this means that

1990
01:13:07,590 --> 01:13:04,880
we will be able to observe

1991
01:13:09,750 --> 01:13:07,600
the faintest and most distant objects in

1992
01:13:12,310 --> 01:13:09,760
the universe to really understand

1993
01:13:13,189 --> 01:13:12,320
how those very early stages of galaxies

1994
01:13:16,709 --> 01:13:13,199
formed

1995
01:13:18,630 --> 01:13:16,719
and also to reveal new planets as well

1996
01:13:20,470 --> 01:13:18,640
so thank you so much for listening and

1997
01:13:23,270 --> 01:13:20,480
i'll be very happy to answer any

1998
01:13:28,149 --> 01:13:26,390
all right thank you laura and

1999
01:13:29,990 --> 01:13:28,159
i'm actually going to start with a

2000
01:13:33,110 --> 01:13:30,000
comment from the chat that actually

2001
01:13:35,990 --> 01:13:33,120
reflected my own thoughts um

2002
01:13:39,350 --> 01:13:36,000
it said uh i can't remember who this was

2003
01:13:42,070 --> 01:13:39,360
wow we've come a long way in 100 years

2004
01:13:43,750 --> 01:13:42,080
yeah i think that's to me that's exactly

2005
01:13:45,910 --> 01:13:43,760
what your talk is done because

2006
01:13:48,390 --> 01:13:45,920
it started back when we only had one

2007
01:13:51,590 --> 01:13:48,400
galaxy and it was the entire universe

2008
01:13:52,790 --> 01:13:51,600
and goes out to really explain just how

2009
01:13:55,110 --> 01:13:52,800
much we've learned

2010
01:13:56,149 --> 01:13:55,120
about galaxies in the last hundred years

2011
01:13:57,830 --> 01:13:56,159
yeah

2012
01:13:59,189 --> 01:13:57,840
so uh let's see there were a ton of

2013
01:14:00,550 --> 01:13:59,199
questions here and

2014
01:14:02,550 --> 01:14:00,560
grant and i are going to have a heck of

2015
01:14:05,590 --> 01:14:02,560
a time trying to

2016
01:14:08,709 --> 01:14:05,600
figure out the best ones um

2017
01:14:11,110 --> 01:14:08,719
but there were a lot of

2018
01:14:12,470 --> 01:14:11,120
questions about all right are we really

2019
01:14:14,709 --> 01:14:12,480
not going to get

2020
01:14:15,910 --> 01:14:14,719
messed up by this collision okay we

2021
01:14:16,630 --> 01:14:15,920
always get this question about galaxy

2022
01:14:19,669 --> 01:14:16,640
collisions

2023
01:14:22,709 --> 01:14:19,679
and somebody put it um strongly like hey

2024
01:14:23,270 --> 01:14:22,719
we're gonna collide at 250 000 miles per

2025
01:14:25,750 --> 01:14:23,280
hour

2026
01:14:29,669 --> 01:14:25,760
and we won't be messed up what's going

2027
01:14:32,870 --> 01:14:29,679
on here attack that just one more time

2028
01:14:34,149 --> 01:14:32,880
again it's a very good point and i it

2029
01:14:37,189 --> 01:14:34,159
really goes back to those

2030
01:14:40,470 --> 01:14:37,199
scales of space so yes

2031
01:14:42,550 --> 01:14:40,480
gravity is an amazing force and it's

2032
01:14:44,390 --> 01:14:42,560
really driving these two monsters

2033
01:14:47,350 --> 01:14:44,400
together and will completely

2034
01:14:47,750 --> 01:14:47,360
kind of you know reshape them into one

2035
01:14:50,709 --> 01:14:47,760
new

2036
01:14:51,990 --> 01:14:50,719
amazingly named vinyl galaxy milk

2037
01:14:54,070 --> 01:14:52,000
dromeda

2038
01:14:57,030 --> 01:14:54,080
but really the separation between those

2039
01:14:59,669 --> 01:14:57,040
stars means that

2040
01:15:01,110 --> 01:14:59,679
the kind of uh the influence of of that

2041
01:15:03,910 --> 01:15:01,120
star you know of its

2042
01:15:04,470 --> 01:15:03,920
planets it's so close we are so close to

2043
01:15:06,709 --> 01:15:04,480
our sun

2044
01:15:07,990 --> 01:15:06,719
compared to those really vast distances

2045
01:15:09,910 --> 01:15:08,000
in space

2046
01:15:11,350 --> 01:15:09,920
that those stars will likely just really

2047
01:15:14,630 --> 01:15:11,360
kind of

2048
01:15:16,229 --> 01:15:14,640
smoothly pass by each other but there is

2049
01:15:19,990 --> 01:15:16,239
an interesting component there

2050
01:15:21,750 --> 01:15:20,000
there is gas and while this gas and dust

2051
01:15:23,590 --> 01:15:21,760
you know it's not quite like the dust

2052
01:15:24,709 --> 01:15:23,600
you would find in your house this dust

2053
01:15:27,750 --> 01:15:24,719
is like a very

2054
01:15:29,669 --> 01:15:27,760
fine smoke it's a very fine mist so

2055
01:15:31,750 --> 01:15:29,679
maybe this might kind of

2056
01:15:33,430 --> 01:15:31,760
have some effect maybe if that's kind of

2057
01:15:35,110 --> 01:15:33,440
raining down on the earth's atmosphere

2058
01:15:37,430 --> 01:15:35,120
but we have this pretty great

2059
01:15:38,630 --> 01:15:37,440
shield in around the earth's atmosphere

2060
01:15:44,550 --> 01:15:38,640
of our magnetic

2061
01:15:47,910 --> 01:15:44,560
those effects will be relatively minor

2062
01:15:49,270 --> 01:15:47,920
and as i mentioned in five billion years

2063
01:15:51,430 --> 01:15:49,280
we'll have something else to be worrying

2064
01:15:53,669 --> 01:15:51,440
about

2065
01:15:54,709 --> 01:15:53,679
in that the sun will be engulfing the

2066
01:15:58,149 --> 01:15:54,719
earth anyway

2067
01:15:59,910 --> 01:15:58,159
so um yeah it's it's uh

2068
01:16:01,590 --> 01:15:59,920
who knows what's going to get us first

2069
01:16:03,270 --> 01:16:01,600
but obviously we will figure out how to

2070
01:16:03,910 --> 01:16:03,280
move to titan first right or something

2071
01:16:07,430 --> 01:16:03,920
like that

2072
01:16:09,990 --> 01:16:07,440
yeah yeah that could work out yeah okay

2073
01:16:10,550 --> 01:16:10,000
so um grant uh let me bring grant

2074
01:16:12,390 --> 01:16:10,560
justice

2075
01:16:13,830 --> 01:16:12,400
in he's been following the chat and

2076
01:16:17,110 --> 01:16:13,840
answering a few questions in the

2077
01:16:22,229 --> 01:16:17,120
chat grant what uh i love i always love

2078
01:16:27,510 --> 01:16:25,270
for our speaker today all right so

2079
01:16:29,270 --> 01:16:27,520
um i'll get started because i will never

2080
01:16:32,830 --> 01:16:29,280
not take an opportunity to have

2081
01:16:35,990 --> 01:16:32,840
us harp or talk up james webb

2082
01:16:39,030 --> 01:16:36,000
um somebody wanted to see

2083
01:16:42,149 --> 01:16:39,040
if it's true that we cannot see through

2084
01:16:44,550 --> 01:16:42,159
things like the milky way or nebulae or

2085
01:16:47,110 --> 01:16:44,560
like large dust clouds or what have you

2086
01:16:50,470 --> 01:16:47,120
and since this is a james webb thing

2087
01:16:52,870 --> 01:16:50,480
figured we could talk about it yeah so

2088
01:16:54,709 --> 01:16:52,880
using those optical wavelengths so what

2089
01:16:57,990 --> 01:16:54,719
we can see with our eyes

2090
01:16:58,229 --> 01:16:58,000
um a lot of stuff is just obscured from

2091
01:17:00,229 --> 01:16:58,239
us

2092
01:17:02,229 --> 01:17:00,239
but if we move to those redder

2093
01:17:02,950 --> 01:17:02,239
wavelengths like i showed in that last

2094
01:17:06,229 --> 01:17:02,960
slide

2095
01:17:08,390 --> 01:17:06,239
you can pierce through a lot of that

2096
01:17:10,790 --> 01:17:08,400
material and you can start to see

2097
01:17:11,430 --> 01:17:10,800
objects on the other side of that dust

2098
01:17:13,830 --> 01:17:11,440
and gas and

2099
01:17:15,590 --> 01:17:13,840
even within those clouds so it's really

2100
01:17:16,550 --> 01:17:15,600
using those longer wavelengths that

2101
01:17:19,430 --> 01:17:16,560
we've built up

2102
01:17:21,350 --> 01:17:19,440
a pretty amazing three-dimensional view

2103
01:17:24,070 --> 01:17:21,360
of what our galaxy looks like

2104
01:17:24,470 --> 01:17:24,080
we can measure you know where the stars

2105
01:17:26,149 --> 01:17:24,480
are

2106
01:17:27,669 --> 01:17:26,159
in those spiral arms and we can see

2107
01:17:28,149 --> 01:17:27,679
where that gas is and everything like

2108
01:17:29,830 --> 01:17:28,159
that

2109
01:17:32,550 --> 01:17:29,840
so we have this kind of you know we put

2110
01:17:33,750 --> 01:17:32,560
on our um infrared goggles and we can

2111
01:17:37,270 --> 01:17:33,760
see through

2112
01:17:38,630 --> 01:17:37,280
and we can see more of the structure um

2113
01:17:40,630 --> 01:17:38,640
so it's really using those longer

2114
01:17:42,149 --> 01:17:40,640
wavelengths and and james webb will

2115
01:17:44,790 --> 01:17:42,159
really just open up

2116
01:17:47,189 --> 01:17:44,800
a whole new area of space and you're

2117
01:17:49,189 --> 01:17:47,199
going to see some amazing images come

2118
01:17:50,870 --> 01:17:49,199
from space telescope and the team here

2119
01:17:51,910 --> 01:17:50,880
um yeah it's it's going to be awesome

2120
01:17:53,830 --> 01:17:51,920
when we start to see

2121
01:17:57,189 --> 01:17:53,840
some of the things that we haven't seen

2122
01:18:05,990 --> 01:18:01,350
okay that sounds good uh what what next

2123
01:18:10,390 --> 01:18:08,630
can we measure lateral motion how many

2124
01:18:12,870 --> 01:18:10,400
and by that i think the person meant how

2125
01:18:16,070 --> 01:18:12,880
many axes can we actually

2126
01:18:16,390 --> 01:18:16,080
track motion in these celestial objects

2127
01:18:18,950 --> 01:18:16,400
like

2128
01:18:19,669 --> 01:18:18,960
obviously it's space so there's multiple

2129
01:18:21,270 --> 01:18:19,679
yes

2130
01:18:23,030 --> 01:18:21,280
and grant i think that was specifically

2131
01:18:23,830 --> 01:18:23,040
in terms of the andromeda galaxy wasn't

2132
01:18:28,229 --> 01:18:23,840
that

2133
01:18:28,790 --> 01:18:28,239
andromeda so thank you for asking i

2134
01:18:31,030 --> 01:18:28,800
actually

2135
01:18:33,350 --> 01:18:31,040
did have a section of my talk on on the

2136
01:18:35,030 --> 01:18:33,360
sideways motion of andromeda but i

2137
01:18:36,390 --> 01:18:35,040
cut it because it does go into a bit

2138
01:18:40,229 --> 01:18:36,400
more detail

2139
01:18:41,030 --> 01:18:40,239
so in theory yes andromeda is hurtling

2140
01:18:44,070 --> 01:18:41,040
towards us

2141
01:18:45,910 --> 01:18:44,080
at this great speed but what if it was

2142
01:18:48,149 --> 01:18:45,920
also traveling sideways

2143
01:18:49,110 --> 01:18:48,159
at an even greater speed it could really

2144
01:18:51,030 --> 01:18:49,120
mean that we're

2145
01:18:52,870 --> 01:18:51,040
not going to collide with andromeda

2146
01:18:55,030 --> 01:18:52,880
anytime soon and it may do kind of a

2147
01:18:57,750 --> 01:18:55,040
slow spiral in

2148
01:18:58,709 --> 01:18:57,760
but using the hubble space telescope

2149
01:19:02,149 --> 01:18:58,719
researchers

2150
01:19:05,750 --> 01:19:02,159
at space telescope actually measured

2151
01:19:08,630 --> 01:19:05,760
the speeds of i think it's

2152
01:19:10,070 --> 01:19:08,640
maybe thousands maybe uh maybe hundreds

2153
01:19:13,350 --> 01:19:10,080
of thousands of stars

2154
01:19:16,470 --> 01:19:13,360
in andromeda they measured the micro

2155
01:19:19,990 --> 01:19:16,480
shifts in those stars and said

2156
01:19:23,750 --> 01:19:20,000
how fast is andromeda moving

2157
01:19:24,470 --> 01:19:23,760
that way on the sky the measurement they

2158
01:19:27,669 --> 01:19:24,480
made

2159
01:19:29,189 --> 01:19:27,679
is so freakily accurate it's one of the

2160
01:19:30,310 --> 01:19:29,199
most accurate measurements made in

2161
01:19:33,110 --> 01:19:30,320
astronomy

2162
01:19:34,709 --> 01:19:33,120
it was i figured it out a long time ago

2163
01:19:37,350 --> 01:19:34,719
it was something like if you were

2164
01:19:38,390 --> 01:19:37,360
on the international space station

2165
01:19:40,390 --> 01:19:38,400
orbiting earth

2166
01:19:43,270 --> 01:19:40,400
it would be like being able to measure

2167
01:19:46,390 --> 01:19:43,280
like the the growth rate of a human hair

2168
01:19:49,270 --> 01:19:46,400
it's wild um but

2169
01:19:49,669 --> 01:19:49,280
what they found is that andromeda isn't

2170
01:19:52,149 --> 01:19:49,679
really

2171
01:19:54,070 --> 01:19:52,159
moving sideways it's on a direct

2172
01:19:55,110 --> 01:19:54,080
collision course it's coming straight

2173
01:19:57,189 --> 01:19:55,120
towards us

2174
01:19:58,870 --> 01:19:57,199
so yes we can measure those lateral

2175
01:20:01,830 --> 01:19:58,880
motions in space

2176
01:20:02,790 --> 01:20:01,840
um and some amazing scientists did with

2177
01:20:05,830 --> 01:20:02,800
hubble and

2178
01:20:06,629 --> 01:20:05,840
yeah it's coming straight for us right

2179
01:20:08,950 --> 01:20:06,639
this um

2180
01:20:09,669 --> 01:20:08,960
uh relates to what i did in the news

2181
01:20:11,189 --> 01:20:09,679
summary

2182
01:20:12,950 --> 01:20:11,199
talking about taking uh hubble

2183
01:20:14,709 --> 01:20:12,960
observations 20 years apart

2184
01:20:16,470 --> 01:20:14,719
and being able to see those really

2185
01:20:17,990 --> 01:20:16,480
really really tiny motions

2186
01:20:19,750 --> 01:20:18,000
now in what i showed you could actually

2187
01:20:21,350 --> 01:20:19,760
physically see them with the eye

2188
01:20:23,510 --> 01:20:21,360
this was so small that you had to use

2189
01:20:25,830 --> 01:20:23,520
computers to actually go in

2190
01:20:27,430 --> 01:20:25,840
and very finely measure them and yeah i

2191
01:20:29,669 --> 01:20:27,440
will note for the audience that

2192
01:20:30,950 --> 01:20:29,679
what my background here is actually an

2193
01:20:33,830 --> 01:20:30,960
image of

2194
01:20:35,350 --> 01:20:33,840
stars in andromeda this uh this the

2195
01:20:37,350 --> 01:20:35,360
globular cluster over here

2196
01:20:40,470 --> 01:20:37,360
that's a globby cluster in the andromeda

2197
01:20:42,709 --> 01:20:40,480
galaxy not in the milky way

2198
01:20:43,669 --> 01:20:42,719
i i just loved this image because it was

2199
01:20:46,310 --> 01:20:43,679
like whoa

2200
01:20:47,750 --> 01:20:46,320
i mean we're seeing what hubble would

2201
01:20:48,870 --> 01:20:47,760
have you know given his eye teeth to be

2202
01:20:51,990 --> 01:20:48,880
able to see

2203
01:20:55,189 --> 01:20:52,000
yeah and this was all part of a massive

2204
01:20:56,149 --> 01:20:55,199
um survey of andromeda that um raja was

2205
01:20:58,070 --> 01:20:56,159
involved with to

2206
01:20:59,189 --> 01:20:58,080
the fat survey which i think is a great

2207
01:21:01,110 --> 01:20:59,199
name um

2208
01:21:03,189 --> 01:21:01,120
the panchromatic hubble andromeda

2209
01:21:06,070 --> 01:21:03,199
treasury so it's really using

2210
01:21:07,189 --> 01:21:06,080
the huge data set there that they could

2211
01:21:10,470 --> 01:21:07,199
then measure those

2212
01:21:12,550 --> 01:21:10,480
micro shifts over a period of time as

2213
01:21:14,149 --> 01:21:12,560
frank mentioned

2214
01:21:15,990 --> 01:21:14,159
all right we've got an i'm sure we have

2215
01:21:19,350 --> 01:21:16,000
more questions

2216
01:21:22,629 --> 01:21:19,360
yes very much so um all right

2217
01:21:29,750 --> 01:21:24,310
i said i mentioned aliens on youtube so

2218
01:21:32,790 --> 01:21:29,760
i'm not surprised that this film

2219
01:21:34,950 --> 01:21:32,800
we'll avoid those um how can you tell

2220
01:21:35,990 --> 01:21:34,960
cepheid variables apart from other stars

2221
01:21:38,629 --> 01:21:36,000
that pulsate

2222
01:21:39,430 --> 01:21:38,639
or are variable in other ways that you

2223
01:21:42,790 --> 01:21:39,440
can

2224
01:21:43,590 --> 01:21:42,800
identify them this is an excellent

2225
01:21:46,070 --> 01:21:43,600
question

2226
01:21:47,750 --> 01:21:46,080
and one that actually kind of is it is

2227
01:21:50,709 --> 01:21:47,760
quite hard to tell

2228
01:21:51,189 --> 01:21:50,719
there are some variable stars that vary

2229
01:21:55,590 --> 01:21:51,199
but

2230
01:21:57,189 --> 01:21:55,600
not on kind of any regular um time scale

2231
01:21:58,709 --> 01:21:57,199
so there are different types of stars

2232
01:22:02,149 --> 01:21:58,719
mira variable stars

2233
01:22:05,510 --> 01:22:02,159
i did a project on those in andromeda

2234
01:22:06,629 --> 01:22:05,520
so basically spectra are your friend

2235
01:22:09,430 --> 01:22:06,639
here

2236
01:22:11,270 --> 01:22:09,440
when you can measure a spectrum of light

2237
01:22:13,830 --> 01:22:11,280
you can look out for the chemical

2238
01:22:14,629 --> 01:22:13,840
signatures within stars to be able to

2239
01:22:18,229 --> 01:22:14,639
kind of tell

2240
01:22:20,550 --> 01:22:18,239
what they are you can tell um

2241
01:22:22,550 --> 01:22:20,560
kind of how big they are and their mass

2242
01:22:23,189 --> 01:22:22,560
and so that's one way that you can tell

2243
01:22:25,990 --> 01:22:23,199
exactly

2244
01:22:27,189 --> 01:22:26,000
what that type of star is but in those

2245
01:22:29,030 --> 01:22:27,199
early days when

2246
01:22:31,350 --> 01:22:29,040
hubble was really just measuring the

2247
01:22:33,669 --> 01:22:31,360
pulsing variable stars

2248
01:22:34,950 --> 01:22:33,679
he you know broadly said we're just

2249
01:22:37,270 --> 01:22:34,960
going to say they're regular

2250
01:22:38,229 --> 01:22:37,280
and he got a pretty good measurement you

2251
01:22:41,590 --> 01:22:38,239
know

2252
01:22:44,550 --> 01:22:41,600
there's some variable stars that can

2253
01:22:47,430 --> 01:22:44,560
muddy the waters in there

2254
01:22:48,709 --> 01:22:47,440
and in fact hubble got the wrong type of

2255
01:22:50,950 --> 01:22:48,719
variable star

2256
01:22:52,950 --> 01:22:50,960
um so he measured it as being like 500

2257
01:22:55,350 --> 01:22:52,960
kilometers per second instead of

2258
01:22:57,030 --> 01:22:55,360
you know 100 or 50 kilometers per second

2259
01:22:58,870 --> 01:22:57,040
right if i remember correctly he

2260
01:23:00,790 --> 01:22:58,880
there's a type one and a type two as

2261
01:23:02,310 --> 01:23:00,800
astronomers always seem to do

2262
01:23:04,149 --> 01:23:02,320
he thought it was this one and it was

2263
01:23:05,590 --> 01:23:04,159
another one but you know he he

2264
01:23:07,910 --> 01:23:05,600
he proved that you know it was an

2265
01:23:09,669 --> 01:23:07,920
external galaxy first of all that was

2266
01:23:11,910 --> 01:23:09,679
the big thing and then you know the

2267
01:23:14,070 --> 01:23:11,920
number had to then of course be refined

2268
01:23:15,750 --> 01:23:14,080
for the hubble constant there yeah good

2269
01:23:17,430 --> 01:23:15,760
enough and in astronomy order of

2270
01:23:19,990 --> 01:23:17,440
magnitude if you're in the right

2271
01:23:21,430 --> 01:23:20,000
park you can you can certainly rule out

2272
01:23:23,590 --> 01:23:21,440
some things you can rule out that

2273
01:23:26,149 --> 01:23:23,600
andromeda is just sat in the halo

2274
01:23:27,750 --> 01:23:26,159
of the milky way right i keep trying to

2275
01:23:31,430 --> 01:23:27,760
tell my wife that you know factor of two

2276
01:23:37,510 --> 01:23:35,030
what else we got grant all right so

2277
01:23:39,189 --> 01:23:37,520
i'll take one i'll i'll get us one more

2278
01:23:41,750 --> 01:23:39,199
and depending on how we go here

2279
01:23:43,030 --> 01:23:41,760
i have an extra um this one's a little

2280
01:23:46,550 --> 01:23:43,040
bit more out there

2281
01:23:47,350 --> 01:23:46,560
which is for it uh if mass if mass and

2282
01:23:50,310 --> 01:23:47,360
time are

2283
01:23:51,669 --> 01:23:50,320
linked uh would larger objects be more

2284
01:23:55,510 --> 01:23:51,679
affected by time

2285
01:23:58,709 --> 01:23:55,520
and or gravity than smaller objects

2286
01:24:01,750 --> 01:23:58,719
mass and time are linked

2287
01:24:03,350 --> 01:24:01,760
i don't know meaning what what effect

2288
01:24:05,110 --> 01:24:03,360
i i think what this person is trying to

2289
01:24:08,550 --> 01:24:05,120
say is what effect

2290
01:24:11,669 --> 01:24:08,560
uh does our perception of celestial

2291
01:24:14,790 --> 01:24:11,679
objects get affected over distance

2292
01:24:17,990 --> 01:24:14,800
by time and gravity in

2293
01:24:19,910 --> 01:24:18,000
both lensing with the telescopes and in

2294
01:24:22,550 --> 01:24:19,920
how we can observe them over distance

2295
01:24:25,350 --> 01:24:22,560
because i know we use some of that with

2296
01:24:25,830 --> 01:24:25,360
adjusting for like gravitational lensing

2297
01:24:27,669 --> 01:24:25,840
and

2298
01:24:29,270 --> 01:24:27,679
in the cases of things that are very far

2299
01:24:32,310 --> 01:24:29,280
out there uh we

2300
01:24:34,229 --> 01:24:32,320
can also use some of that to establish

2301
01:24:36,470 --> 01:24:34,239
the constant motion

2302
01:24:37,830 --> 01:24:36,480
but are those two things linked in any

2303
01:24:41,350 --> 01:24:37,840
way and how do they help us

2304
01:24:43,110 --> 01:24:41,360
with our science yeah so i mean i think

2305
01:24:44,390 --> 01:24:43,120
for this if i understand the question

2306
01:24:49,430 --> 01:24:44,400
correctly we

2307
01:24:51,990 --> 01:24:49,440
we tend to rely pretty heavily on um

2308
01:24:52,950 --> 01:24:52,000
relativity for this so that link between

2309
01:24:54,950 --> 01:24:52,960
mass and time

2310
01:24:56,550 --> 01:24:54,960
because time is actually quite a

2311
01:24:59,990 --> 01:24:56,560
flexible

2312
01:25:03,430 --> 01:25:00,000
number um and so it uh

2313
01:25:06,629 --> 01:25:03,440
the heavier the gravitational well

2314
01:25:09,669 --> 01:25:06,639
you're in um the slower the time

2315
01:25:13,189 --> 01:25:09,679
goes um and so

2316
01:25:15,750 --> 01:25:13,199
uh yeah we we have to adjust for

2317
01:25:17,189 --> 01:25:15,760
mass and time in some calculations when

2318
01:25:20,070 --> 01:25:17,199
you're thinking about

2319
01:25:21,750 --> 01:25:20,080
um gravitational lenses uh you know you

2320
01:25:22,950 --> 01:25:21,760
have to adjust for this even when you're

2321
01:25:25,990 --> 01:25:22,960
thinking about

2322
01:25:28,550 --> 01:25:26,000
gps systems and and how we you know they

2323
01:25:30,310 --> 01:25:28,560
all have to make that correction um so

2324
01:25:33,350 --> 01:25:30,320
if i think i think i've understood the

2325
01:25:35,110 --> 01:25:33,360
uh question okay but um but yeah so yes

2326
01:25:37,510 --> 01:25:35,120
we always have to factor those in

2327
01:25:38,950 --> 01:25:37,520
and the heavier objects will always have

2328
01:25:40,229 --> 01:25:38,960
those effects more because of that

2329
01:25:41,910 --> 01:25:40,239
relation

2330
01:25:43,270 --> 01:25:41,920
and i would just add because there was a

2331
01:25:45,990 --> 01:25:43,280
lot of conversation

2332
01:25:48,229 --> 01:25:46,000
um in in the chat about this that this

2333
01:25:49,110 --> 01:25:48,239
is a localized effect on the the massive

2334
01:25:51,510 --> 01:25:49,120
objects

2335
01:25:53,750 --> 01:25:51,520
it doesn't really affect globally when

2336
01:25:55,910 --> 01:25:53,760
you compute a cosmology you're not

2337
01:25:56,950 --> 01:25:55,920
you know necessarily having to deal with

2338
01:25:58,550 --> 01:25:56,960
that on that

2339
01:25:59,910 --> 01:25:58,560
it's really with the localized effects

2340
01:26:01,590 --> 01:25:59,920
where you have the the high

2341
01:26:04,629 --> 01:26:01,600
concentrations of mass

2342
01:26:06,070 --> 01:26:04,639
that will take care of that

2343
01:26:09,030 --> 01:26:06,080
let's see i think we have time and more

2344
01:26:10,790 --> 01:26:09,040
question i have one more

2345
01:26:14,950 --> 01:26:10,800
and it's a good one unless you have one

2346
01:26:19,030 --> 01:26:18,070
i'm gonna let you do your job okay all

2347
01:26:21,750 --> 01:26:19,040
right

2348
01:26:24,149 --> 01:26:21,760
dr laura what is your favorite star in

2349
01:26:27,189 --> 01:26:24,159
andromeda

2350
01:26:30,790 --> 01:26:27,199
wow well they don't have names so

2351
01:26:33,590 --> 01:26:30,800
it's quite hard um but so

2352
01:26:35,990 --> 01:26:33,600
the project that i did um with raja

2353
01:26:38,790 --> 01:26:36,000
actually i was looking at stars that had

2354
01:26:40,550 --> 01:26:38,800
emission lines so like those features in

2355
01:26:42,709 --> 01:26:40,560
the spectrum

2356
01:26:44,790 --> 01:26:42,719
um so we were looking at lots of these

2357
01:26:46,229 --> 01:26:44,800
bright blue stars these massive hot

2358
01:26:49,270 --> 01:26:46,239
stars that were

2359
01:26:50,310 --> 01:26:49,280
um giving off these these kind of

2360
01:26:51,910 --> 01:26:50,320
beacons of light

2361
01:26:53,750 --> 01:26:51,920
that we could be able to tell what they

2362
01:26:56,390 --> 01:26:53,760
were so i really like

2363
01:26:58,310 --> 01:26:56,400
that collection of stars so some of them

2364
01:26:59,669 --> 01:26:58,320
were mira variables so a different type

2365
01:27:01,990 --> 01:26:59,679
of variable star

2366
01:27:03,830 --> 01:27:02,000
and some of them were massive really

2367
01:27:04,629 --> 01:27:03,840
massive bright hot blue stars and

2368
01:27:07,270 --> 01:27:04,639
they're spinning

2369
01:27:08,709 --> 01:27:07,280
so fast that they don't look round they

2370
01:27:10,790 --> 01:27:08,719
actually look oblate

2371
01:27:12,870 --> 01:27:10,800
and um so they're really kind of like

2372
01:27:13,750 --> 01:27:12,880
you know squished footballs rugby balls

2373
01:27:16,830 --> 01:27:13,760
if you will

2374
01:27:18,709 --> 01:27:16,840
um that helps with my analogy of

2375
01:27:20,950 --> 01:27:18,719
football

2376
01:27:22,550 --> 01:27:20,960
that's really cool and as i'll pass on

2377
01:27:24,149 --> 01:27:22,560
from the chat before i turn it over to

2378
01:27:26,229 --> 01:27:24,159
frank to bring us home

2379
01:27:27,430 --> 01:27:26,239
uh everyone has been very pleased with

2380
01:27:28,870 --> 01:27:27,440
your analogies

2381
01:27:31,270 --> 01:27:28,880
they say thank you it made it much

2382
01:27:33,750 --> 01:27:31,280
easier to understand great

2383
01:27:34,790 --> 01:27:33,760
thank you thank you thank you everyone

2384
01:27:37,350 --> 01:27:34,800
thank you man

2385
01:27:38,310 --> 01:27:37,360
i'm glad that was anything was clear so

2386
01:27:43,270 --> 01:27:38,320
all right

2387
01:27:43,990 --> 01:27:43,280
we cut off after 90 minutes and we hit

2388
01:27:46,310 --> 01:27:44,000
that

2389
01:27:47,110 --> 01:27:46,320
um thank you again again laura this was

2390
01:27:49,830 --> 01:27:47,120
wonderful

2391
01:27:51,430 --> 01:27:49,840
and um i'm sure you're gonna get lots of

2392
01:27:52,950 --> 01:27:51,440
views on youtube because this

2393
01:27:54,870 --> 01:27:52,960
and people watching it over and over

2394
01:27:56,950 --> 01:27:54,880
again to go you know i didn't get that

2395
01:27:58,629 --> 01:27:56,960
i got to watch that again to really let

2396
01:28:01,030 --> 01:27:58,639
that sink in because

2397
01:28:01,669 --> 01:28:01,040
some of this is mind-blowing uh we will

2398
01:28:05,510 --> 01:28:01,679
be back

2399
01:28:07,910 --> 01:28:05,520
on march 2nd uh with tom brown

2400
01:28:09,669 --> 01:28:07,920
talking about the hubble space telescope

2401
01:28:11,430 --> 01:28:09,679
from cosmological concept

2402
01:28:13,830 --> 01:28:11,440
to alien atmospheres he's going to

2403
01:28:15,990 --> 01:28:13,840
mention aliens too

2404
01:28:17,430 --> 01:28:16,000
i have a great chat back then thank you