Searching for Life in Distant Solar Systems | Nathan Mayne | TEDxTruro

Hey so I'm gonna talk to you about a pretty big question and the question is are we alone are we the only intelligent life that exists in the universe that's a pretty big question and it's one that's kind of preoccupied humankind for probably all of our history and it's something that is inspiring me and I'm probably gonna spend the rest of my career trying to answer that question and my job today is to try to sort of convince you I guess that we are very close tantalizingly close to perhaps answering that question and the key discovery in the recent times what we've only really were able to look at other planets in our solar system for evidence of other life and we're still ongoing that search is still happening we're looking for very simple forms of life but in the early 90s we discovered the first exoplanet and that's a planet orbiting a star other than the Sun a distant world and the simulation that's playing here this is taken directly from a model from my research group where we've adapted the same model that predicts Earth's weather and climate and we've applied it to an exotic world and the idea we also collaborated with a graphic designer to sort of give a scientifically informed visualization now the thing that drives me is to try to connect the study of our changing climate with this diverse range of exoplanets we'll talk more about that in a moment but to sort of set the scene I guess if you only remember two things from this talk I might be a bit disappointed but the two things the first one is in order to answer that question of are we alone in the universe sighs is there any intelligent life we really need to understand better how atmospheres work that's absolutely critical atmospheres are critical and the second point that love you to remember is that we need to plant more trees and we'll get to that at the end so we're going to start a little bit closer to home on earth beautiful earth which has what's called a replete biosphere as life everywhere you look now life in itself with a very simple definition it sort of takes resources from the environment and it emits waste so it's in a kind of balance in a sense with the environment a very simplistic sense and that allows us to define two concepts habitability and habitability is just saying could an environment support life and as astronomers we really sort of boil this down I wasn't meant to be Joe we boil it down to liquid water the presence of liquid water we know that liquid water is fundamental to transport information and resources around our body so habitability or you might have heard the phrase habitable zone is just an attempt to say could this environment support liquid water now also as we emit waste into the environment so for example as we breathe we affect the environment around us so if you take a test tube of the Earth's atmosphere you sort of seal away some gas the balances of those gases will change over time until it reaches an equilibrium it's not in equilibrium it's not in balances it's what's called a chemical disequilibrium and that gives us the concept of bio signature if we were able to find imbalances of gases caused by biology then that gives us evidence that life may exist somewhere now on earth we have very sophisticated models to model our weather and climate which despite sort of opinions are actually pretty good and we're also using them to peer back in time to about three billion years ago during the Archaic period where we think life first sort of originated on earth those same models that we're sort of simulating these these situations at Exeter we're also trying to do it by looking forward in time of what's happening as we put more and more co2 into the atmosphere and we potentially heat the atmosphere up so lots of puzzles and lots of things we need to find out and we're using that with a quite a sophisticated model framework to attack those problems now if we take a sort of step towards exoplanets we can look at the other planets in our solar system which are kind of earth-like be very careful of that phrase earth-like just means they're roughly the same size as Earth I guess and as astronomer I can be really vague like that that's about about the same size and we have three planets like that Venus Earth and Mars and we know or at least we think that there may have been opportunities for material to be exchanged between these three planets and actually Venus and Mars may have been very habitable and similar to Earth in the past but right now Venus is pretty close to hell it's about 500 degrees in a trained self uric acid whereas Mars is the other end of the scale it's freezing cold so we know that only earth is habitable at the moment and we're really using the same models the same thinking the same thought processes and the same people to try to understand why these plants diverged and that's really critical because if we were to discover these three types of planets around a distant star oh they're all left like well maybe they could all be habitable so we need to understand the sort of sensitivity of why these planets diverge in order to understand exoplanets so then let's move on to exoplanets so until the early 90s the only planets we knew over that existed were in our solar system and as a scientist I wasn't back then but now I would have bet that planets existed elsewhere but we had no evidence then we discovered the first one in the early 90s and that was followed by about three and a half thousand more I don't know what the number is now it goes up every day the point is we see a lot of exoplanets the very first thing we learn about exoplanets or planets in general is that we really don't understand very much at all in our solar system we use that as a template to understand how planets might have formed and evolved and actually what we found well in the solar system for example there's no planet in between the size of Neptune and Earth nothing exists so we said okay that must be telling us something about the formation program process however now we know that probably the most common planet there is is one that's in between the size of Earth and Neptune and that's called a super earth unsurprisingly or a mini Neptune equally imaginative so we're learning very quickly that our solar system isn't a sort of template now the other planets or the other sort of planet we're going to talk probably for the next five minutes or so are called a well their planets that are more like Jupiter and they're very very close to their parent star in our solar system all the small rocky things are closed and all the big gaseous things are far away whereas these planets they're very easy to see and detect then like Jupiter and they're very close to their star so they're very hot so we scratched our heads for a long time with lots of clever people and we came up hot Jupiters great name so why are they so important hot Jupiters are at the moment the only real class of planets where we can sort of peer into their atmospheres and understand how they work exoplanets that is now what Jupiter's because they all bit so close to their parent star they're obviously blasted with radiation and they're very hot and as they move in front of the parent star they block out some of the light from that star there's a dip in the light and that tells us how big the planet is the bigger it is the more likely it blocks out and vice versa so already we're getting some information the second thing we can do we can sort of go even further and as the planet moves in front of the star the light is filtering through the atmosphere and leaving its spectral imprint on that light so using that we can back out what the atmosphere might be made of and we can start to detect comical chemical compositions so that's ringing the bell that maybe at some point we'll be able to check bio signatures by looking at the chemical compositions and their balances now because these planets are so close to their parent star they become what's called tidally locked the same force that raises tides in Cornwall that we can go and surf from the waves the moon and the Earth's gravitational sort of connection happens here so the planet is locked so the same face always faces the star and that means during its orbit we can see the night side come into view and then as it rotates around the warmer or the hotter day side and why is that important well that gives us a temperature contrast between one side and the other and we know from understanding the earth one of the most important things the kind of engine of the climate is the fact that it's hotter at the equator and colder at the pole that drives much of our weather systems so by understanding the temperature gradients in these planets we have our engine for our climate so we're learning quite a lot we can observe a lot about these planets we can even find their mass from how much they make the star wobble we can go one step further than that it's been done twice now we can actually look at the emission from the planet itself and using the same effect the Doppler effect that makes a siren go higher-pitched as it comes towards you and lower as it goes away that's sort of squeezing we can use that to back out velocities of the wind in the atmosphere of this planet so we've measured the wind speed in the atmosphere of a planet tens of light-years away that's pretty cool so as a theorist that's exciting because I get all of these numbers and I can tinker my model and abuse the Met Office model and change all the settings took me about three and a half years I'm sort of downplaying it a little bit and there's a lot of work and we got it to run in order to simulate one of these planets a particularly boring Li named planet HD 189 which is this simulation you see now what we can do is check our simulation against the observations to make sure it's giving us the right answer but we can also then start to understand the bits we can't see what drives the atmosphere how do they work these things are really surprising objects they're twice bigger than they should be we thought we understood the physics of how they grow with math but the two times bigger and we don't really understand how they redistribute the heat around the planet there's lots of lots of puzzles and these models are allowing us to do that but the thing that I'm working hard to do is to try to connect this in one framework so I have the same model that understands earth climate the same one that understands what Jupiter's and the reason for that is we know the hot Jupiters are not habitable there's no liquid water and there are definitely no bio signatures but they are allowing us a test ground a sort of steps towards being able to look at smaller planets and interpret their atmospheres and be confident when we do claim it's habitable or detect biosignatures now we're taking the steps along that path because we're already detecting earth-like planets but again be very careful earth-like here does not mean you know it has a test goes and motorways it just means it's about the same size it's got the same amount of stuff as Earth has we've already discovered over 200 of these orbiting distant stars and in fact just recently we found out that our next-door neighbour Proxima Centauri B has an earth-like planet orbiting it in fact the very closest star to earth has a planet probably not that far away in size from Earth so just as just to give you our strana Murs work when i say about the same size as Earth the estimate of this is between 1.3 and three times earth so yeah large uncertainties but we're getting there now the problem here is that most of these planets that are earth-like we're discovering around small stars it's easier to see the light blocked out by small planet if your star is smaller and these small stars they're called M dwarfs and they're much cooler than the than the Sun they're much smaller they're much cooler so their light is much redder and then what also much more active they have sort of more x-rays etc higher energy emission so what we don't know really we're only just starting to learn is how on earth how on earth how on an exoplanet does that cool red star light interact with the atmosphere does it drive it in the same way as it happens on earth does photosynthesis even work probably not but is there an alternative so although it's incredibly exciting time to be alive we still have a lot of work to do so if you know of any young people to show an interest in physics or climate science or anything like that I'm going to try and solve these problems in my career but I'm probably not going to get there we need young people to be interested in this field and help us because it's there's so many things to solve ok we're also starting to see other planets earth-sized also orbiting stars like the Sun so that obviously makes things a little bit easier because we don't have to worry about the different star the cooler radiation etc and in fact to Exeter with a few other universities were also started to design projects and missions to try and detect these planets expressly and we have a mission called the Tara Hunter experiment which we're trying to focus on stars just like the Sun that are nearby so that we can detect planets like Earth orbiting them and then go on to study them so in we've already discovered one they're not not the Tara Hunter experiment another survey did so there will be these are coming planets like Earth are coming we will be finding them and then of course we need to start to work out if we can understand their atmospheres and then if we can detect things like bio signatures etc so it's kind of exciting there's a lot of work to be done but I want to leave you on a kind of final note if you like which is we've discovered about 3,000 exoplanets I said and for using those statistics what we're able to do is back out a sort of occurrence rate by looking at how sensitive our instruments are when we did when we detect things when we don't we can back out how frequently a star should have a planet like Earth orbiting it and we think that frequency is about 10% so in our galaxy at least about 10% of the stars have a planet that's sort of earth-like or earth size I guess orbiting it now in our galaxy we know we have about 20 billion stars like the Sun a huge number so if we take 10% of those that's 2 billion earth-sized planets in our galaxy alone that's a huge potential habitable reservoir now this image behind me is the Hubble Ultra Deep Field a very famous image and this is about the size of the moon on the night sky that's the kind of field of view of this instrument and in that field of view they discover 10,000 galaxies and not all of them like the Milky Way but still imagine how many times you can fit the moon next time you're kind of out on a summer's evening looking at the night sky imagine how many times you could sort of fit the moon across the night sky and each one of those blocks each one of those areas has 10,000 galaxies in it and each galaxy might well have two billion Earth's so I guess I'm laboring the point here but there's a lot of Earth's a lot of us but again it doesn't mean they all have cellphones and motorways if you asked me to bet my house then yes I would say life exists elsewhere in the universe but I don't know yet and I'm a scientist and currently we only know we only have evidence of life on this planet which is why we should enjoy that cherish it and essentially plant more trees to look after it a bit better thank you very much for your time

Channel: TEDx Talks

Views: 20,102

Rating: 4.6949153 out of 5

Keywords: TEDxTalks, English, United Kingdom, Science (hard), Exploration, Science, Space

Id: YYx-IaOXiug

Length: 15min 31sec (931 seconds)

Published: Mon Oct 03 2016