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you

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[Music]

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this is update on a project that I'm

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doing in sorrow seekers like with the

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amateurs and the audience looking at a

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systematic database of gases that could

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be biosignatures on the world the logic

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is this we don't know what gases other

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types of biochemistry might produce and

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so we take a list of all possible gases

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and filter them through different

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selections to come up with ones that

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could be atmospheric signatures down the

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bottom here and I'm going to be talking

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about the geochemical fourth positives

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things that might be produced by

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geochemistry Janish talked at last AB

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saikhan about the list so I'm not going

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to talk about this it's a long list or

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writes 14,000 molecules some of which

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are quite weird from a biochemical point

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of view I have talked about the ones

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that might be readily produced by

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geochemical processes because those are

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poor biosignatures we see them on an

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exoplanet we don't know whether they are

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produced by life or by geochemical

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processes and so the question I want to

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ask is which of that 14k are likely to

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produce by geological processes and the

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initial step we're doing this in the

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thermodynamic one say are they

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thermodynamically likely to be made we

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want a general solution not the sort of

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this is what are still solution but

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obviously I'm going to use as a testbed

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to see what the methods work at all

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that's an amazingly bright light okay

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so this is the approach we want the if

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we're going to look at the

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thermodynamics of whether something is

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produced we want to know what the free

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energy of formation is you can get that

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from a database for this web book

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database thank you or if it's not known

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then you can calculate it from semi

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empirical quantum mechanical methods we

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use the game's software to do that over

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96% of the molecules in our database

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don't have reported free energies of

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formation so we had to calculate

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enthalpy entropy and specific heat

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capacity to work out the energy of

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synthesis the other question is since

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this from what so volcanoes put out a

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lot of gases

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and you can assemble them in different

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ways to make a molecule so for example

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this is glycine and you could make live

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seed by this reaction here in theory

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okay I'm not saying how it happens or

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from this one here these are different

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gases and heads will have a different

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free energy of formation and how do you

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compensate for that well you don't you

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look at all of them all combinations of

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the different volcanic gases co2 methane

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nitrogen ammonia and so on and say what

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is the maximum free energy and that's

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that the sort of ultimate limit of the

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minimum which suggests that this might

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happen in a volcanic system so this is

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the sort of data we get out this is the

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number of molecules produced out of our

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database and this is the free energy of

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formation from elements in their

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standard state there's quite a spread

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but it's not terribly interesting

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because the elements are not in their

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standard state in volcanic gas

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this is synthesis from volcanic gases

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over here again number of gases and free

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energy of formation anything lower than

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zero means that's a negative free energy

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of formation that means that the

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reaction as modeled here is

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thermodynamically favored quite a big

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spread and some obvious to the bulges

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and humps and the curve these guys over

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here are mostly compounds with

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phosphorous atoms in these guys over

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here mostly compounds with nitrogen

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atoms in which is interesting and we

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haven't followed up on that yet I said

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working progress okay and you could do

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that for all temperatures so that was

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just one temperature one pressure you

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can do that for all temperatures and

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variety of pressures so here we have

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temperature and here we have free energy

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of formation and the color scale here is

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the number of molecules falling into

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that free energy range for that

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particular temperature and those look

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very pretty and they tell you that as

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you increase pressure from one bar here

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to 217 this is arbitrary by the way this

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is just the critical pressure of water

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you get more molecules that are likely

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to be formed thermodynamically in other

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words it's lower down the scale

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the maximum value is higher than the

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minimum value always nice to have that

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sort of check in your software as you

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increase the temperature the number of

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sable molecules goes down and all this

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is totally expected what isn't expected

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is that is this sort of kink here in the

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curve and that's where it becomes

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thermodynamically favored on the right

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to make the molecules from methane and

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on the left to make them from carbon

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dioxide and hydrogen this can be done

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for everything and then what we ask is

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how many molecules for below Delta G

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equals zero here in other words our

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thermodynamically favored under these

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conditions

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are sort of average volcanic gas if you

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look up in apps for a chemistry book

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what gases the volcanoes put into the

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atmosphere and they come up with a

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number that is an average earth is not

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an average so to try to get a little bit

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nearer to what they're actually does we

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looked at actual volcanic locales 53

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locales around 60 different papers

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recording nearly 600 measurements of the

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actual gases coming out of the earth and

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did the modeling with that with the

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partial pressure of gases at these

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locations the temperature at them we

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discarded the ones below a hundred

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degrees because this is the gas phase

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the issues with that is of course that

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not all gases are measured at all

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locations so we had to fill in the ones

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that weren't measured and there are two

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ways to doing that you could run a

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dynamic model of that gas or

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thermodynamic model of the whole system

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and that gives slightly different

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results which we're still working on so

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this is the sort of result you get this

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is the number of volcanic sources out of

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that collection of 53 low castle or 487

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measurements at which a gas is

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thermodynamically favored to be produced

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under those Delta G of formation

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synthesis from those gases less than

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zero and this is the number of gases for

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which that number is is right so over

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here this is one bar that's 30 bars

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because I was going to do one and thirty

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and a thousand other files

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turns out to be on the slide over there

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so you know and the large majority of

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the gases are not produced in any

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volcano good they are not likely be

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false positives as you increase the

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pressure that number goes down there's a

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small number that's produced virtually

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everywhere and that includes things like

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sulfur dioxide carbon dioxide hydrogen

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sulfide which we know volcanoes produce

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so again that that's nice okay so for

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that one this is the same data plus at a

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slightly different way this again this

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this time is temperature along here each

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of these dot is one volcano and this is

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the number of gases produced by that

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volcano and it drops off with

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temperature as you'd expect that's

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really weird outliers up here though and

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if you plot the data a slightly

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different way so this is temperature

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again along here but fraction of water

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in the gases the arrived original

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fumarole or volcanic vent produces

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nineteen ninety-five percent of water as

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the gas some of the produce much less

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and these large circle fear size of the

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circle is proportional to the number of

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molecules being produced under this

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thermodynamic modeling in the system the

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dry gas is down here seem to produce a

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lot more potential gases okay but the

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important point to remember these are

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not the same gases in each volcano so

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I've looked at these four examples here

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and a sort of average one up here and

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this is the number of gases produced by

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those modern to be produced by those I

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should say and and how many a shared

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between them so system a here the 628

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molecules we predict as having a

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negative free energy of formation that

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are not formed than any other system and

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there's a there's a tweak to this

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because actually a B C and D are all the

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same volcano they're all the Lascar

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volcano in Chile at different times so

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different places different times

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different volcanoes all produce

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different materials and we're going to

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have to capture this if we want to model

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this on an exoplanet

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okay so interim conclusions are as you'd

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expect above a thousand Kelvin you

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produce very little complex molecules

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they're all the obvious volcanic gases I

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was going to put something fairly rude

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up here to say well gosh isn't that

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surprising but I didn't phosphorous

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compounds very few bullet arts if you

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see a bullet are phosphorous compound in

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our exoplanets atmosphere say wow lots

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of molecules likely produce dry sites

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produce more what we don't know yet is

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where they accumulate biases and the

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data phosphorous is a problem and many

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we've also asked how I deal with

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phosphorous I will tell you either in

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questions or afterwards but the big

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problem is that these are a very biased

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set of volcanic gas samples and their

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bias for a very simple reason if you

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want to sample this fumarole here it's a

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bit hazardous but reasonably safe give

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on a sample this active volcanic crater

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here it's a really dangerous but

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possible and if you want to sample this

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well frankly you just don't so but these

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sort of things put about third to a half

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of all the volcanic gases in the

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atmosphere so that this is entering the

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number of things we want to do next

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which I'd be really key to talk to

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people about particularly other worlds

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what other volcanic gas models might be

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put into those worlds and that's it are

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huge thank the yeah no she's down I

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can't see you and they were and Sarah of

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course who's been my sponsor and doing

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this for many years and thank you for

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thank you we have time for a couple

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questions excellent that's what I like

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to see so MLS I'll ask a question if

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there are none so you mentioned right

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there at the end other models for

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different types of planets I mean do you

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have any thoughts of where you're going

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to start there I really like to start on

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Io ok I think iOS just fantastic part

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and looking brilliant color but it is a

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it's a known body for which you know is

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very active it has a lot of volcanic

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activity beyond that a Sol maneuvers who

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told me that the volcanoes and Venus

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have being detective of active but how

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do you measure the gases of them it

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needs something where you can actually

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say what is the gas coming out of this

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and then plug that into these sort of

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calculations so I will be number one and

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then after that you know the fields open

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thank you very much

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any any other questions you have to go

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up to the microphone unfortunately

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there's no one who's coming around with

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them all right so my question is very

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similar to that which is we can find

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these volcanoes around other bodies and

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measure the gases but what kind of lab

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work could be done to actually measure

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the gases and they're free energies is

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that a viable Avenue as well on to so

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this that there's work to measure more

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gases and to fill in all those gaps

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there's a lot of this is based on

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calculated thermodynamic parameters and

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some of the calculations are quite badly

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off because if you compare them to

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what's actually measured you know I mean

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they're off by tens of kilojoules per

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mole and so there's a first

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approximation this is okay but measuring

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those thermodynamic parameters would be

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really useful but difficulty with this

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and we talked about this at the Nexus 7

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our summer the doing those measurements

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and doing reaction rate to measurements

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which is also important for this it's

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really difficult really time consuming

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and then once you've spent in our six

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months doing it for one set of chemicals

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you get one data point in one database

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and no kudos at all

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so those are sort of risk reward time

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reward imbalance that don't know how to

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get around that but if there's a