StarTalk Podcast: Cosmic Queries - Life on Exoplanets with Sara Seager

[Music] this is star talk i'm your host neil degrasse tyson your personal astrophysicist and this week is a cosmic queries edition the always popular cosmic queries and the topic the always popular search for life in the universe and i've got with me is my co-host matt kirschen man hey hey neil how you doing okay i spent all day yesterday trying to memorize the name of your podcast it's probably science right it is i was here for another variant but thank you i stumbled in my efforts there i found a podcast called sometimes or mostly science it's a whole other podcast oh we hate them no we've got a running rivalry with them it's going to be it's going to totally have rivalries i got to make sure i get your stuff right it's going to come to violence at some point probably so i know a little bit about the search for life but not as much as our guest today uh our guest today is sarah seeger sarah welcome to star talk thanks for having me today yeah so sarah let me get your full title up here so uh your professor of aeronautics and astronautics physics and planetary science at mit is that no they left out a few categories no no no it's it's because exoplanets and the search for life is an incredibly interdisciplinary talk topic and it draws upon all those different fields excellent but but but between you and me can i call you're a planetary scientist right that's right yes yes i mean my home is really in astrophysics so okay you could call me an astrophysicist or a planetarium okay so you're in the club in the club so uh i guess the search for life in the universe has to necessarily include the search for exoplanets right they go together but is that part of our bias not necessarily we do i mean we're we're definitely pterocentric we're we definitely are narrow-minded but at the same time yeah like earth-centric you know and on earth we believe that for the origin of life we need a place for ingredients to concentrate and it's it's hard to imagine ingredients just you know concentrating in in the vastness and that low density of outer space okay so this concentration thing i think is under celebrated out there i mean in the public that people we take it for granted that we have rocks and buildings and mountains and people and for in our greater universe nothing is together i mean mostly it's mostly empty and where it's not mostly empty it's highly rarified and so planets are really special places is that right is that yeah very special because they do concentrate complex molecules they concentrate elements nutrients and everything we need am i right in thinking they are substantially less special or at least less rare than we thought they were even 5-10 years ago yes actually we are slowly making ourselves less and less precious less and less special no sarah it's okay to know that you're not just supposed to tell people that i i think that's nice about science i like the fact that scientists sort of switch between going you're incredibly special and you're not special we do we love thinking back to the copernican revolution where before copernicus the model of the universe was that our earth literally was at the center of the universe all the planets and the sun and the stars apparently all orbited earth i think i've heard is it andrean described this sequence uh some combination of her and the in the carl sagan uh camp uh referred to it as the sequence of great demotions for whatever we imagined ourselves to be plus there was some rebuttal to that um i forgot the fellow's name but he wrote i think convincingly that the idea that the idea that we are in the center is not necessarily an elevated place if heavens are above us right so the center could be the slag heap of where everything collects and your ultimate goal is to ascend from that to greater places so but in either case the the location was unique i think so so in his mind we're like the plug hole of the universe we're sort of the drain so so sarah you was it natural to transition from exoplanet discovery to the search for life it wasn't someone had to nudge you or was it just obvious as the next thing to do you know every scientist is different and i've sort of been the random walk type of scientist like work on a problem and see a more interesting problem and then move over slowly i like the dog being distract distracted by the squirrel you know yeah you can't keep it so but but when you started out um in the in the late 90s um we we didn't didn't know many exoplanets and even those that we did it was fun to think of aliens on them but there was no research program there yet so so it seems to me you were there at the birth of this if not having birthed it yourself yes and in fact but just to go back even further before my time perhaps even before yours but in the decades past if you look back like even you know just after um the time of sputnik like in the early 1960s there's actually a report from a think tank kind of company and it actually talks about planets and exoplanets and the chance for other earths and even in the decades after that you know there were always studies on how would we go about finding another earth and so when exoplanets was born in the mid 1990s and yes i was there i was a graduate student working on exoplanets at the time you know they were hot jupiters they were not suitable for life in any way but slowly those two things came together you know all the past decades of thinking about earth's then switching gears to the hot giant planets and so the thought of finding earth and life it was kind of always there in the background even though it might have been a bit of a stretch and just to be clear the the jupiters that you're referring to being hot was it was easier to find really massive planets first compared to low mass planets so you're going to find it jupiter first and we and they're hot because because why because they're very close to the star so close to the star that as heated by the star they're just hot okay so the jupiters but they didn't look like our jupiter so so there again we were not so we we thought we were representative of the universe and we're not i mean at least our solar system right right we always expected to find a jupiter where our jupiter is which is you know five times further from our sun than earth is and instead we found jupiter mass objects within a few you know few day period orbits of the star so even our bias that which shows up every day in race relations and sexism it even shows up in astrophysics it does yeah and you know the funny thing is is just to take that a level further when we people first found these hot jupiters so close to the star we just assumed that they had the same albedo the same reflectance properties as jupiter itself jupiter is quite bright you know you see it in the sky because it's got icy clouds and we couldn't see jupiter in reflected light and with a little more thought we realized wow these hot jupiters they're incredibly dark they're very absorbing they have no reflective clouds most of them wow yeah wow okay so they're not only so the big jupiters that don't look anything like jupiter that's what you're saying like i mean yes and no they don't appear like their atmospheres aren't like jupiter but they're kind of bulk composition they're mostly made of hydrogen and helium that part's the same all right so if you come to this as an astrophysicist planetary scientist and now you want to think about life you gotta start knocking on the doors of biologists so when did all that happen remarkably it really it started happening for me when i had my first staff position i worked at a place called the carnegie institute of science and i was in washington dc and it's quite interdisciplinary there already and they were already part of of working on the somewhat new field back then of astrobiology so i started we're interacting with biologists there and the funny thing was is i got a postdoc there and i signed him up to work with me and it literally took us like nine months before we could even understand each other because our language was so different yeah so you need the coffee lounges you know between uh at the intersections of departments because otherwise we just live in our stove pipes and discoveries go un un uh unattended too and later on i attended an astrobiology conference and i met a remarkable person there who became one of my closest colleagues and so then through him him being a biologist i was able to learn and create more more collaborators and so i mean you have a fascinating story i only recently learned that you've actually collected that together in a kind of a memoir the smallest lights in the universe so congratulations on that memoir nice published by crown in 2020 and because we're all distracted by big explosions and big lights and big things but maybe the smallest lights in the universe i guess these are the exoplanets or it could be metaphor for other things in the book that it's just call attention to other previously underserved domains of the cosmos thanks yeah so so let's get straight let's get straight to this uh what is life you know in exoplanets we have a good excuse for completely avoiding that question and we do we do i'll run it by you i'll run it by you because we have telescopes and we can see atmospheres of other planets we're hoping with our next generation telescopes to see atmospheres of small rocky planets and we're going to look for signs of life by way of gases that might be attributed to life that have accumulated in the atmosphere so we prefer to think about what life does life metabolizes and it may give off gases during that chemical process of metabolism so we conveniently sweep that under the rug and we just talk about what life does are you stupid under the rug because you can't do anything about that question anyway we can't do anything about it and it's just a question that no one wants to agree on what what the answer is so you but you sweep it under the rug and say let's do it life let's observe what life does so you're the atmospheric gases equivalent to the people who study um animal poop for example it's it's things that life does even if you're not studying the life itself that's right that's right not to equilibrate your study with the study of species and actually neil that that's never been done before so that is brand new it's a brand new analogy so you're saying atmospheres on planets are kind of the uh animal remains of the galaxy well the gaseous effluences yes actually that's it that's a great way to look at it actually yep so sarah but but clearly there are gases out there um and i want to get to the q a because matt has them lined up and i don't want to lose any time on that but clearly there's there's some gases let's take methane for example um that we know is the byproduct of life not all life of course but some bacterial life on earth we know that so now let's look to another place like saturn's moon titan oh my gosh it's completely covered in methane so it must be teeming with life so we but it's not so hot where did how what you yeah yeah that's the single most biggest problem that we need to be able to see other gases in the atmosphere and put the gas in question in context with what else is there but even doing that will be it'll still be hard it'll be very like a forensic crime scene you know how do we pick out what is really life what is really not made by life so the gases you list that are the products of life are necessary but insufficient to prove that there's life yes actually and that is the sort of let's call it the dirty secret of the whole field is that we'll never be able to prove it so in forensic crime scene terms you sort of got to distinguish between blood that was caused by the crime and blood that was just previously existing sort of decorative blood in that room precisely just blood that someone had put there that would just naturally be there on the walls in the splatter pattern yeah the normal blood that would that exists in the room i'm sure see sarah is going to put that analogy in her next research paper right let's just add an equation and that's all sciences right and you know it's in an equation it's legit yeah and so on our earth we have methane produced by life by bacteria you know by cows but we also have methane coming out of mid-ocean ridges so in a lot of cases it is definitely ambiguous and methane is natural gas that we have in our stoves right and i'm pretty sure what's coming out of your stove is not cow farts it comes from another location on earth okay so matt we have a couple of minutes left in this segment let's see if we can squeeze in a question okay great well this one i i love the questions that come from uh our younger listeners so this one comes from carrie jenkins an eight-year-old fan i know how long do you think it'll take for us to find other life in the universe well yeah how close are we sarah how many how many more years what do we got here well we actually will have we like to say we'll have the i'm not purposely trying to evade all your questions honestly but i would like to say that we will have the capability to find signs of life very soon with the launch of the james webb space telescope but whether we find life that really depends on what's out there you know if every planet has life if life is extremely common life that makes gases so i if you want a concrete answer i could say anywhere between two years and 30 years let's say okay so this would be the life the usable life expectancy of the james webb space well i was putting the james webb whose nominal life expectancy is five years maybe ten i was thinking of future telescopes beyond the james webb okay and possibly uh missions to the icy moons of jupiter um where there might be life beneath the surface or even life in beneath the surface of mars right i mean why not you're not looking for that life but you got other people top people doing that as well right okay so uh so we might find life or definitely know there isn't life as we know it in the lifetime of this eight-year-old girl well maybe this eight-year-old girl will carry the torch if all the searches we're doing now are exhausted maybe she'll be the one to think of the next new idea oh maybe you all aren't clever enough and we need her to come along and solve all the problems all right we got to take a quick break when we come back more start talk cosmic queries with my friend and colleague sarah siegel we'll be right back we're back star talk cosmic queries search for life edition i got with me my co-host matt gershon matt where do we find your podcast oh just all the podcast places just bang for yourself oh oh that's your all your net your nearby stores have any of them yeah go go to your local uh go to your local podcast supplier and just ask for probably science and they'll find it somewhere in the back there do you also do stand-up comedy i do what what i used to when when indoor things were existed right now i talk into zoom recordings and pretend i'm doing stand-up okay this is during the in the in the covert lockdown yeah that was my day job and hopefully will be again excellent excellent and we have as my special guest sarah seeger who's an astrophysicist planetary scientist searching for the exoplanet searching for life and she's our resident expert to field these questions that matt has solicited from our fan base and this is the patreon fan base so what more do you have matt for us i think also by the way uh we should mention that our guest today isn't the only one with a new book out and you've got a book based on cosmic queries that has a chapter that talks about the search for life oh yes indeed so thanks for mentioning that because i almost forgot i probably wouldn't have forgotten by the end but there's a book called cosmic queries because this format was so successful we said we've got to do more than just put it out there as a podcast so there's a book called cosmic queries that takes all the biggest questions including this one and much of sarah's research that informs this field is contained in that chapter and so in a celebration of cosmic queries as a thing and the search for life as a as a sub thing of the bigger thing we've got sarah sieger so sarah thank you again for being on star talk and for checking in for this so matt what do you have for us well i've got to do another another uh cosmic query question from another young patreon uh listener this comes from violetta and violeta's mum izzy the letter is a 12 and a half year old astro fizzy kid here in alabama yep 12 and a half yes when you're young those halves are important and and asked professor sega i want to know firstly what exactly are biosignature gases and secondly what biosignature gases would earth give off that would be detectable by extraterrestrial life who might be looking for inhabited power planets like ours perfect question yeah or would you not need to look for our biosignature gases because our existence would be pretty obvious because the space junk yes well a biosignature gas is a signature of life it's a gas produced by life that can accumulate in an atmosphere of a planet to a level that we can detect with our telescopes and if there are you know if there's i love to imagine you know there there are intelligent aliens on a planet orbiting a nearby star and they have the kind of space telescopes we're building or hoping to build they would look at our earth and they would definitely see a very strong biosignature gas and that's oxygen and oxygen fills our atmosphere to 20 by volume but without plants without photosynthetic bacteria we would have literally virtually no oxygen so if all the plant life went away you know walked off the earth today how long would it take for our oxygen supply to sort of drop to zero and why would it drop at all why wouldn't it just stay there well we also have bacteria that make oxygen so i'm not sure you know what the division between all of those so no no just take away everything that's making everything take everything away so now we've got 20 oxygen what happens to it well what happens to it is oxygen is a highly reactive gas and it will just react away with other molecules in the atmosphere with lots of things on the surface you know with gases coming out of vents and volcanoes and that oxygen just won't be there so how about over how much time would that take i don't have that number off the top of my head would it happen like next week or in a year no no it wouldn't happen next week it probably wouldn't happen in a year it's probably more like thousands of years or even okay or more okay so yeah so we if we kill all the life the the oxygenation life we can still live out our lives with oxygen subsequent generation will suffocate yes probably we can live without our lives okay so what you're saying is even though this 20 has been stable over the his mostly stable it's not actually a stagnant number because we are constantly producing it and constantly removing it and it just happens to be balanced at this number right a fair way to say it that's a fair way to say it right all right all right matt all right another one this this comes from uh grumpster tough uh all one word i hope i'm pronouncing that even closer correctly what is your most whatever you did it's better than what chuck does with names um what is your most optimistic explanation of the fermi paradox i think we all have our favorite answer to that one first what is the fermi paradox the fermi paradox is the idea that if if there is intelligent life that can harness energy and get in spacecraft and journey beyond their planet that they should have colonized the entire galaxy by now because once they can get to one planet and colonize that they can just keep going and so the fermi paradox is summed up by the question where are they so what you're saying is in the lifetime of the galaxy it doesn't really take that much time if you're intelligent by our measures to build spacecraft and start traveling to planets even if you can't travel at the speed of light right right that over time you would eventually reach planets and and colonize okay so all right so where are they well i i might okay so there's the explanation i think is the real one and then there's the one that i hope is the real one i like the experiment right so matt matt the right they're already here so you know one answer is that it just takes too much energy like we as humans we know now what it takes to get in a spacecraft and go somewhere that's a lot of resources so perhaps they're just not not doing that there's another answer that the intelligent civilization will unfortunately and inevitably self-destruct they'll destroy their planet they'll kill each other they'll they won't ever reach that kind of wouldn't that be the definition of not being intelligent yeah well it would be my explanation that i love is i'll put it to you this way just imagine an ant an ant colony in your house you know what you might have or your apartment and the ants they appear kind of you know dumb but they're somewhat clever right because they have a society and you see them doing like a reconnaissance and i don't know if you've ever had this but you'll see like a few of them kind of looking around and they might come across like a piece of cat food on your counter or something and then shortly thereafter you have a huge stream of them and they're all coming to get this cat food in like a little river well you can mess them up if you like wipe away their trail for a moment they kind of get lost but i want you to imagine you know neil matt having a conversation with those ants like tell them about the universe tell them about the hubble space telescope and the vastness of of the number of stars in galaxies like how on earth tell them about calculus yes yes so what i love to imagine is that these to these intelligent aliens out there that we are like the ends like why and how would they they contact us okay so matt sarah is bumming us out now first we're insignificant now we're just plain stupid well also i think it is worth pointing out there are there are different i mean like sarah was alluded to there are very different types of intelligence so you know i've been to university you've both spent a lot more time in academia that we've all met people who are incredibly smart in specific ways and otherwise idiots so you know maybe they have the ability to travel across galaxies but they're not the ability to not shoot themselves within a very short amount of time and maybe the official answer is they think we're idiots either they think we're idiots or we think they are for having self-destructed before they could get here oh there it is touche all right so matt give me some more so along the lines of uh interacting with other civilizations eric gross asks let's say we discover proof of life not in our own solar system but on some distant celestial body would there be any meaningful scientific value of the discovery or opportunity to expand upon the knowledge it may of course have broad societal and emotional effects but would science practitioners have any real hope of gaining more information about life forms that are at a minimum of 4.3 light years from earth yeah so sarah i love that question because generally when we think of scientific discoveries or advances we think okay in five years or ten years engineers will get a hold of it and they'll make some new device and we'll all be living better and differently and so life somewhere else that you can't actually have a conversation with even if it's intelligent and are you getting secrets from that i mean what if you can't or can you are we missing something here it's such a great question i mean we are so wrapped up in the emotion and the excitement of the journey of exploration and of being the first who can try to find out what's what's out there so in a practical sense not really i mean we're not we're not doing this to find anything practical that said wouldn't it be amazing if there is life intelligent life on the nearest star system for light years away we could have a very slow conversation but we could imagine no witty repartee there right send them a message and you know four years later you'll get their message back and we could exchange ideas about technology so if we wanted to be practical like that's probably the most practical avenue so um but in terms of biology unless we learn from them through these radio signals what their sort of biochemistry is like we wouldn't get to compare dna or if they have dna at all you wouldn't be able to do any sort of in-situ kind of comparisons to advance biology on life i would guess right correct no that's correct that's correct yeah but i don't want to sound like who was that philosopher uh 150 years ago who said the stars they're just lights on the sky and and we can know you know how right they are in the location but we will never know what they're made of right and and think about this like we're just here now imagine a thousand years from now you know 10 000 years from now we may have a way to get to this imagine if there's life on intelligent life on that planet and we do like a sample return we fly something by they send something up we grab it we you know gravitational slingshot around their star and we come back okay so uh so all right i'll just think a thousand years from now rather than next week okay well what you just said those that answer segway's quite neatly into this question which i like and i'm going to combine two different questions from what tom says who asks what forms of communication are most likely to be able to cross between the stars and um trumpet wom who says how do you think we will overcome the language barrier if we ever meet another sentient lifeform i love it and and sarah remember that movie um arrival arrival rifle so i got in trouble for and i i knew i was gonna get in trouble for saying this i said in the movie arrival they brought a physicist and a linguist to try to communicate with the alien when they should have brought an exobiologist and a cryptographer and i got so much [ __ ] from the linguists out there because this is their one time to appear in a movie and there i am just dissing them but what is your opinion about how we would actually communicate i mean i love that movie i love the concept that it may be so difficult that we may we may not find a way to communicate okay so now she just swept under the rug neil doesn't like any of my answers but she's sweeping it i don't know how big her rug is but but how about mathematics how about symbolism symbology how about i mean yeah i like all that assumes you're okay with them or not i like it i like it it would have to be something that is fundamental in a very mathematical way i agree with that because math apparently applies across the universe so if they discover something that is cosmic universal it'll have to be the cosmic universal things we discovered as well i presume right so i wonder so i think one of our greatest triumphs is the periodic table of elements if we can like show that to them and see if they have a version of it right because it'd be a lot of pantomiming initially i would guess yes before anybody actually uh communicated um so it is funny that you know aliens often just spoke english you know right right that's why the arrival is so great it's such a great movie because it's the first time they have these beings that have no way to really really interact with us right right so matt give me one more question before we wrap up this middle segment i will do and for the people who are watching the video rather than just the audio i apologize for the other life form that keeps walking across my lap while we're trying to record i have no way of communicating with him uh well uh so i'm also going to combine these two questions because they they're in similar themes so rob carter asked when searching for life on other planets is there a priority of what type of life you look for for example would a land-based land-based life-form take precedence over an aquatic species and so forth and then jonathan r brown asks carbon-based life on earth developed in the oceans and diversified exponentially from there spreading to land and beyond life on other worlds may develop from a different elemental base and begin on land or in other environments could et life be too alien for us to recognize as life and what is the baseline and we'll get to that after this break see what i did there uh so i those are brilliant amazing questions that are the foundations of so much science fiction storytelling but uh sarah you have the commercial break to figure out what the answer before you sweep this one under the rug okay when star talk cosmic queries returns we're back star talk cosmic queries search for life edition uh sarah are you um active on social media do you have a twitter account yes i do it's a prof sarah seeger p-r-o-f prof sarah secret and s-e-a-g-e-r right okay excellent so we can all follow you there and i assume you talk about fun stuff like and your research and and and the like and facebook as well you can just search for my name sarah seeger on facebook as well okay excellent excellent all right so matt we left off with a brilliant pair of questions uh tell me the two names who asked today yes that was rob carter and jonathan r brown and they were both asking about the types of life forms that you might find on other planets with land-based aquatic and so on and whether we'd even be able to recognize those things as life or must they be based on carbon we won't have a chance to see that life we'll only see what life does we'll see the byproducts of that life because the telescopes aren't good enough yet right right we can't we only see the we'll only see the planet far away we won't even see it in some cases it'll be a pale blue dot or we'll just see it's we'll just see its atmosphere as backlit by its star so we won't see the animals so the point is when you study the chemistry of the atmosphere it's a remarkable feat of of observational astrophysics because the light from the star behind it passes through the transparent atmosphere and then the molecules leave their fingerprint and that's what you're studying right that's the way we're studying exoplanet atmospheres today that's right so we're a long way off from you watching something wave to you in the in the telescope we are but you know funnily enough it doesn't stop you got an answer yeah i do have an answer that's good well i was gonna say it doesn't stop us from speculating about what life might be like i want you to just imagine for a moment because there are exoplanets are so diverse they're different masses and sizes and we're imagining their atmospheres are all different imagine a planet where the atmosphere is so massive and heavy that it's a similar density to water so imagine you have a water ocean and above that is a heavy dense atmosphere you could imagine things like flying fish that can just move between the atmosphere and the water because it's the same same density yeah we've all we love to imagine a planet that is somewhat dark because of a massive atmosphere and we like to imagine this idea of birds with giant wings that are photosynthetic that the wings are like giant plant leaves they can fly up to where there is sunlight and gain energy from the sun that way sarah that reminds me some science fiction writer forgive me for not remembering there was a punch line in it where the aliens come to the earth they see what we all do here and then they return to their home planet and they report on what they discovered and they said they're all made of meat and and because we basically eat each other right life eats other life unless you're a plant in which case you eat right so i mean just think about that so if you are a bird that has photosynthetic wings then to eat you like you just said you just go to a altitude where you get the sunlight and then come back down and you're not killing anything for yourself then you would presumably be pray for whatever is in the lower levels because they aren't accessing their sunlight you'd want to make sure they're photosynthetic too but imagine a whole world where that's the case and they come visit us and we have all these slaughterhouses and not just us other animals eat other animals and this would look like a really bloody nasty place to them very nice would you guys ever think about that no no but it sounds pretty scary okay so tell me also about a carbon-based life how yeah what do you think sam couch actually asked this specifically while we're doing that he uh sam asks um is it possible to have life elsewhere that is not carbon-based and if so what would that look like compared to carbon-based life and what would be the requirements for that life to survive yeah there really hasn't been a lot of solid work done in that area it's it's really hard to construct you know a biochemistry of like a completely different type of life out there we're not sure if silicon based life is even really possible we think silicon you know a lot of our silicon here on earth for example it's locked away into rocks and there's just not a lot of silicon we think silicon compounds are often they dissolve in water too easily so i think the jury is still out on that one okay so even though silicon makes the same families of molecules as carbon does because they they're top and bottom to each other on the periodic tables as we learned in high school chemistry that they'll all make the same kinds of molecules but you're saying the the other properties of silicon molecules make them wholly different from what carbon is giving us yes so so so our search for life is justifiably carbon-based not to put words in your mouth but that's kind of what you're saying yeah you said it well that's right matt did she sweet no i i think that rug is fully lifted and the items underneath are exposed and all right all right okay this one this one's pitting host against guest here josh v asks dr tyson has spoken in the past star talk episodes about the idea of goldilocks zones being antiquated at best and possibly the wrong approach to searching for life what is professor sega's opinion on the use and definition of goldilocks zones as it applies to what galactic locations are prioritized in searching the vast cosmos wow actually this is one where neil and i agree actually so just to go into some detail the habitable zone it's a good construct the goldilocks zone it helps us think of where we should be looking for planets but in reality i think it really depends on the individual planet like i want you to imagine a planet that instead of having an atmosphere like ours that is mostly nitrogen and it has a good amount of oxygen imagine a planet that has a hydrogen atmosphere dominated by hydrogen did you know hydrogen is a nasty potent greenhouse gas way worse than any of the gases we have on our planet earth so a planet with hydrogen it turns out it could still be the right temperature far outside to what we think of as this traditional goldilocks zone because it has such a powerful greenhouse and they wouldn't call it nasty they would be thankful for it they would need it or their planet yes they would need it right right right so i like to think of habit habitability concept as being you know planet independent not your location in the galaxy or your location in your own planetary system but dependent on the properties of the planet so that's an enlightened modern view of the concept of a zone so the zone is not a it's a virtual zone in that sense because it can take it's it can be in places that are not just in the in the narrow-minded swath that's around the sun so that's good i hadn't i hadn't thought about these other kinds of goldilocks zones you're referencing and for all we know even the definitions we've come up with now 20 30 years from now carrie and violetta the eight-year-old or the eight and twelve-year-old listening to this in their day they might look back at our definition broadened definition of a goldilocks don't say what do they know they because they at fault there could be like life inside of volcanoes or something i mean who knows right right and we haven't observed any rocky exoplanet atmospheres yet we're just beginning so right right right okay so what i want to do now is go into a semi-lightning round and so sarah pretend you're on the evening news and the whole interview is going to last just a couple of minutes and so so this is your sound bite quiz can you give us a sample you've been very good in this program so far so i think it'll come out in flying colors so matt so uh i i i think i know the answer to this one but uh andrew guendro asks my question is about the probability of life in the universe finding each other if we think of the universe as infinite and the axis of time as infinite does it stand to reason the probability of life in different areas of the universe finding each other on both axes time and space approaches zero my guess is no but uh i want to hear from the scientists sarah okay i didn't totally get that the last part of that so he's saying if everything's infinite life should i shouldn't find each other i think i think the question is if we're dealing with an infinite universe and a finite amount of life would that not be so far apart from each other that it couldn't find it each other no he had he added another dimension it let's say life is there and we're here and we go there when we find them okay if space is infinite that reduces the likelihood that they're just going to be there they're going to be probably much farther away from us that's the first axis on this the other axis is maybe the life is there now but they're not going to be there in 100 years so you have to intersect not only in time but in place and if both the time axis and the place axis are infinite what hope do we have of ever making contact i think i got his question i think he's got i think i got that you got it yes yes it really all depends on how common life is if life is rare then yes that question is an answer is valid but we all want to believe that we will we see but we see the ingredients for life everywhere and so we have every reason to hope that on each rocky planet that's the right temperature that there's a chance for life there okay and but but in terms of how how far we've actually searched my favorite reference there is an an analogy given by a jill tarter of the seti institute and i've i've so good i've given this 100 times since then and i we got her to say it on star talk so we we have it wrong i know what you're going to say i know what you're in our archives it's you can ask how much of the universe has researched before we start saying there's no life here and if you look at all the parameter space time space frequency of bandwidth right you could be trying to say hi in one frequency and they're trying to hide another frequency and their ships passing in the night and you both conclude that there is no sign of intelligent life so she said it's like going up to the ocean scooping a cup an empty cup filling it with ocean water looking at it and saying there are no whales in the ocean so in terms of how much total volume that of space time frequency is searchable and so that was depressing but fascinating at the same time for me right right but at the same time now i'm going to turn the tables and do the opposite of trashing all the the comments like if you're scooping up that one glass of water surely there is some kind of life in there and so when we're we're scooping up by looking at the nearest planets you know if we look at we're we're looking at the nearest planets and you know if there is life there where wait let me try to say this better so we're thinking that we can look at the nearest stars and the nearest planets and that the ingredients for life are everywhere and that they should come together often enough that we have a chance of finding signs of life excellent excellent so that's like taking a scoop of anywhere soil on earth there's going to be life in it right or any air air parcel even air very cool very cool matt let's all right david newman says is it possible that the galaxies we observe relatively easily are less likely to have life than the dwarf galaxies are wandering stars in deep space which are more difficult to see could wandering stars or dwarf galaxies in deep space be less threatening to life well at the moment we're only able to observe the very nearest stars we can't see other galaxies so that question's out of our out of our purview at the moment however each star is fairly isolated and each star has its own planetary system as far as we can tell so it shouldn't matter which galaxy the planet is in in relation to whether life is there or not and we see the same kinds of stars in most galaxies are there differences of course but that repeats enough i i agree with you we will be perfectly happy searching stars in our own galaxy without having to go to others just to wonder if it's different but another point implicit there is there are some galaxies that have very rocking active nuclei with very deadly radiation coming out and it could be that some galaxies are hostile to the formation of complex molecules and more peaceful galaxies like the dwarf galaxies that they may be more hospitable i mean we don't really know this yet and i agree sarah there's still much more searching to go before we start creating a galactic model for what life would or should be like let's get one more question matt see if we can get it i'm really on a combining kick today because these are both quite philosophical jeff thomas asks we as a species love to stimulate our senses by watching movies listening to music telling stories and more assuming an alien civilization is interested in leisure could we hypothesize what a stimulation of different senses would look like outside of our familiar five and look for evidence of such things and then chris hampton says what effect do you think the discovery of alien life would have on society would borders eventually dissipate and self-identification move from russian american et cetera to earthling how long would the initial pandemonium laughs i think um in one sound bite i think i was going to ask neil for that because neil is so articulate and good at speaking i think you should take a crack at it i'll i'll take a quick crack at it it is interesting when you find something that's more other than you are from each from [Music] among yourselves it does have a it is does act as a kind of binding force and sometimes for the good sometimes not but i had hoped that we would have had this kind of binding force in the face of battling kovid kovid was like an alien then it doesn't care what your skin color is or your gender or gender expression or who you have sex with or any it doesn't care it'll infect you and and that would be a good place to band together and fight and we failed that test so i i i wish i had more confidence than i currently do and how we would react collectively as a species to uh an alien be they friendly or hostile and the others about what kind of version of stories and art and music and would alien civilization have different from ours or how would we interact with it sarah do you guys think much about the senses that a alien might have no i mean is that is that something that you could look for and look for evidence of or ways that they could have changed their environment to accommodate the different ways that they that they interact with each other the way we do no i mean if you think about it for a moment our oxygen on earth life on earth bacteria cyanobacteria you know billions of years ago they re-engineered our atmosphere they completely changed our atmosphere so it was unrecognizable so we can see giant things like that but small things like that animals do or that aliens would do those are out of our a possibility for now yeah but you're being like straight scientists there but now let me ask you sarah seeger the human being who watches science fiction movies can you imagine well if if an alien had another sense what might it be yeah that's a tough one i don't have a good answer for that i don't i can take any answer it doesn't have to be good well sometimes i i do like to think about our own planet earth and all the intelligent life here you know like the dolphins and octopus and there's a lot of creatures here that we we think are highly intelligent and so i do like to think about how they interact with each other and what signs they give each other my favorite new yorker comic we got to end and was there were two dolphins swimming together and they're looking up at two humans talking to each other looking out of the water and they see them and one dolphin says to the other they face each other and make sounds but it's not clear that they're actually communicating dolphin with brains bigger than ours uh sarah it was been a delight to have you on um and we neglected to even mention that you were co-author on the recent discovery of um [Music] of phosphine a molecule on in the upper atmosphere of venus a possible product of life i know that that result is still getting contested but it's fun to watch science at its best when ideas come forth and people try to explain it in multiple ways so just good luck on that it was great to see you yeah active in that and and in your in your part memoir the smallest lights in the universe it's it's a delight to see that contains a first-hand account not only of your life but the birth of an entire cottage industry in our beloved field of astrophysics uh the search for exoplanets in the search for life itself so great to have you on thank you thanks for having me all right and matt always good to have you man oh it's a pleasure thanks for having me and we'll look for you on probably science yes please thank you i got it in one right and also your book as well now we've got to give that another plug oh sorry another another plug for cosmic queries if you like this format um and if you're listening you probably do because it's one of our most popular uh we just put it all in one book it's got the deepest questions like what is life and what is the universe made of and how how did it begin how will it end and are there multiverses and so we're very proud of that book as a start talk community because it's a lot of it has been inspired by shows like this where you write in and ask your deepest questions and that inspired us to put the book out there and it's a product of the star trek family i'm neil degrasse tyson your personal astrophysicist as always

Channel: StarTalk

Views: 108,817

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Keywords: startalk, star talk, startalk radio, neil degrasse tyson, neil tyson, science, space, astrophysics, astronomy, podcast, space podcast, science podcast, astronomy podcast, niel degrasse tyson, physics

Id: rJgmf2zNHow

Length: 48min 47sec (2927 seconds)

Published: Fri Mar 19 2021