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to fly your car from the moon to the

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earth if a vehicle had a one-to-one mass

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ratio meaning that the fuel tank holds

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as much as the payload it could thrust

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at 1g continuously for 245 days this is

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the kind of figure people are talking

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about for interstellar travel by

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conventional means through normal space

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whatever we might think about

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interstellar travel this obviously gives

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us ample power for maneuvering and

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travel within the solar system so in

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terms of empirical consequences

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detecting neutrinos is extremely

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difficult but there have been neutrino

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detectors in operation some of them are

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actually being called neutrino

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telescopes these days because they

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detect astronomical events literally for

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decades they had already established a

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solar neutrino problem in the late 1970s

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now most of the output of a neutrino

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drive will be muon neutrinos because

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those are produced by the first step in

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the decay cascade and we recall that you

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want to keep the decay cascade short

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because that's what makes the drive more

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efficient ah however the solution to the

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solar neutrino problem that I mentioned

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a moment ago is that neutrinos oscillate

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they change identity muon neutrinos will

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over a sufficiently long flight path

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some fraction of them will transform

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into electron neutrinos which can be

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picked up by the detectors so this

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postulates the possibility of a very

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simple retrospective test for whether

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vehicles that we see deut or that we

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think we see doing violent maneuvers in

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Earth's atmosphere are being powered by

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neutrino drives simply plot the

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direction of the maneuvers in

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three-dimensional space no note what

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direction they're accelerating in

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plot the opposite direction ignoring

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trivial obstacles like a few thousand

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miles of rock and see if they intersect

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a neutrino telescope if they do consult

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their records and find out if they got a

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blip of neutrino events at the

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appropriate time I have no idea how such

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a test would come out but at least it's

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a test that's doable there are also some

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more practical consequences um

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antimatter is a tremendously rich energy

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storage system there is a lot of storage

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stored energy in such a drive equals

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mc-squared a vehicle that crashes or

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even just loses whatever its containment

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system is is going to explode with a

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great deal of power even a kilogram of

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so or or so of antimatter is going to be

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a multi Megaton blast on other things

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this means that shooting them down

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doesn't sound like a very good idea if

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they're using this drive off hand the

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only way I can think of to avoid a

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tremendous explosion on upon crash

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landing is if the vehicle has already

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run out of fuel which when you think

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about it is a pretty good reason for a

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crash landing to happen just as a note

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for possible implications there's still

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speculation about what the Tunguska

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explosion in 1908 was but the estimated

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power of the blast court would

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correspond to the amount of antimatter

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it would power a small vehicle for a few

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hours of Hygiene maneuvering ah so if a

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one one can only imagine what a large

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vehicle powered for more than a few

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hours of maneuvers would what would

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produce if something bad happened um so

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brings me to the end of my talk and I'm

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happy to answer questions a couple of

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questions so just a detail first you

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talked about efficiency improvement from

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the thirty percent to more by pre

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accelerating the matter-antimatter mix

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but from conservation of momentum it

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would seem that whatever you gain from

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the increase by pre accelerating you've

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lost by doing the pre accelerating let

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me let me just ask add something to this

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and then I'll get off the microphone a

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second thing related is that if we are

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to believe the UFO sightings these

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spaceships can make right angle turns

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and so on so any sort of immense

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acceleration from any sort of inertial

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accelerator would slam the poor

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inhabitants of the the spaceship against

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the wall at with tremendous velocity

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therefore it seems like some sort of

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drive would have to turn off inertia

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rather than use it and then finally

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given what you've talked about with this

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very efficient drive how about looking

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for a new green technology okay to

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address those points one after another

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what happens with the pre acceleration

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is that because the neutrinos escape the

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portion of the imparted momentum that

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corresponds to their share of the total

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mass energy just leaves the system

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that's how you get thrust in terms of

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protection against high-gee maneuvers up

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okay geometrically there's no such thing

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as a right angle turn it may require

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enormous acceleration but there is going

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writing about ways to protect against

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high accelerations is another issue but

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in principle

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we we think we can already imagine ways

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to shield human astronauts from

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accelerations up to 100 g or so we don't

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we are missing some of the chemical and

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biochemical technology for that but it's

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it seems to be a solvable problem and I

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did not want to try to branch into too

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many areas of Technology in terms of a

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green technology antimatter has the

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drawback that it is a secondary a fuel

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source it is a storage system rather

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than a power generation system okay

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Bernie and then we'll go to that side of

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the room I'm little surprised to hear

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you say that the most efficient form of

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propulsion is by having very high

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exhaust velocity but the ratio of the

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momentum to the energy it has the

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inverse of the velocity which is the

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opposite what you what you want ah the

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most efficient okay here i am turn

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casting efficiency in terms of how much

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delta v can you get for a certain mass

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of fuel the higher the higher your

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exhaust velocity the less mass you use

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up but the more energy you expend and

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this is simply a fact of life about the

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way reaction drives work and the second

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question is back to what Garrett alluded

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to that the reason you gave you a

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neutrino is to go out in one direction

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the direction that you want is because

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your pre accelerating the antimatter and

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so you've just transferred the

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acceleration process to the antimatter

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acceleration so there you have the same

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problem the same problem of not being

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able to get around Newton's third law

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the the whole point here is to work with

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Newton's third law um if you had a fuel

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lump and you simply shook it back and

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forth accelerated it and then caught it

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and stopped it you would get nowhere

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because you can use this annihilation

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transformation to convert part of it

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into a form that simply escapes out the

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back the amount of thrust you produce in

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the acceleration phase is not completely

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neutralized by the catching process

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square you intercept the portion of the

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inter of the energy that still interacts

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with normal matter then you're using

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that energy to accelerate the next lump

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in the train in a realistic system this

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would be a continuous process but

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thinking of it as a sequence I may makes

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the concepts a bit easier to follow okay

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if stones argh is in the room can you

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start coming up okay and Dale graph oh

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yes sir question I think this summer

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will learn a little bit more about what

185
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went on at Tunguska when the italian

186
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team digs down into that Lake to find

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out whether or not it was from a comment

188
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I'd hit or not so I look forward to

189
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seeing that result I have a comment on

190
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the as a compulsion thing here neutrinos

191
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are really tough to detect and these

192
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detectors I'm aware of that are deep in

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mountains only catch a few hits a year

194
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so maybe there's going to be a change in

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the technology that might help increase

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that hit right now you might want to

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comment on that the third comment I like

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to make is cosmologists do a lot of talk

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about eight years so ninety percent of

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the universe i think is ninety-six

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percent of the universe being dark