Extraterrestrial Life - Avi Loeb

good evening welcome to the Museum of Science I'm James Watson co producer of adult programs and I am so honored and pleased to introduce you to tonight's Reno Family Foundation symposium extraterrestrial life I am so honored to be welcoming our special guests for the evening joining us all the way from Harvard University of course I'm referring to the incredible dr. avi Loeb among dr. Loubs and many credentials he is the chair of the department of astronomy at Harvard University he's also the founding director of the black hole initiative and we are just so pleased to have him here tonight on the stage over the past year or so he has become a leading voice in the conversation about our first known interstellar visitor also known as moi moi and we're gonna hear about all of that tonight and so much more he is a great presentation for you all and towards the end of the evening we will have time to answer as many of your questions as we possibly can hopefully you saw this slide behind me this is how you can submit your questions for dr. Loeb you can go on your smartphones and go to slide o comm and enter the code avi Loeb all lowercase and submit as many questions as you'd like we'll try and get through as many of those as we can a little bit later on and following the full presentation we invite you to keep the night going join us downstairs and the blue wing for a dessert reception with a cash bar and continue the conversation with us before I bring out our special guests I have to thank two very important people without whom tonight would not be possible that of course is Jack and Susie Reno for over a decade now they have continued to support the adult programming initiative here at the Museum of Science and without their support and their contributions programs like this evening and guests like dr. Loeb would not be able to be on the stages here so please join me in giving a very very big hand so Jack and Susie thank you we we look forward to many more collaborations and tonight it's a part of our fall season of adult programming there's still a lot to come over the next couple of months you can pick up our mail or on your way outs and sign up for our mailing list those are the best ways to stay up to date on everything happening here at the Museum for adults like yourself but for now please join me in welcoming to the stage our guest tonight dr. avi Loeb thank you very much James it's a great pleasure to be here today I'll discuss one of the most exciting questions in science perhaps the most exciting but I should start with a confession some of us are not sure yet that there is intelligent life here on earth but that may be an even better reason to look for it up there and so the fundamental question is are we alone and of course either answer to this question yes or no will have deep implications as to our responsibility for the future and I should mention that a week ago the Nobel Prize in Physics was awarded to two astronomers michel mayor and didier queloz who discovered the first planet around a sun-like star and if we imagine life out there the first thing to think about is a planet like the earth around a star like the Sun you know when before we go out to the street we look at our image in the mirror and that's the perception we have of what we might see on the street it's not a bad perception but that's what is natural for us to assume and so finding planets around other stars is the first step in the search for life and the third person who received the Nobel Prize was for the development that was Jim Peebles for the development of our current model of the universe how the universe started from the Big Bang and of course beyond asking the question of whether we are alone there is the question of when did life start if not only on planet Earth where else and how soon how early and what will happen to it in the future for the young people in the audience that's an important question now many of us tend to think that we are at the center of the universe you know humanity as a whole I believe that and a number of religions believe that that the earth is at the center philosophers argued for the Atari Stoll for example and everything centers on us the physical universe is centered around us turned out to be a wrong perception of reality we are not at the center of anything the earth is moving around the Sun and you know when Galileo suggested that he was put in house arrest that didn't change the facts which is an important lesson that science is not about getting more likes on Twitter it's about evidence clearly Galileo did not get a lot of likes at the time but it didn't change the truth that he was advocating and Copernicus was the one to recognize first that the Sun is the center of the solar system now even though we realized that you know the earth moves around the Sun the Sun moves around the center of the Milky Way galaxy so and the Milky Way galaxy is moving in some drifting in some random direction that is an important lesson that we are not at the center of the physical universe but many of my colleagues still believe that we play an important role that we are at the center of the living universe perhaps we are special perhaps we are alone we are unique and various people raised a number of important arguments in this context why the earth is rare and why life on Earth the way we see it is special and unique but I can fully understand this tendency of feeling special by viewing my own daughter's when they were young they tended to think that everything centers on and as time went on they went out to the street and they found other people that look similar and they realize that those people have qualities that may be even better than they're theirs and so they developed a sense of modesty as a result and they matured and ssible is a ssin we are following the same path we tend to think that everything centers on us that's natural because at first you realize things happening around you so you think oh well it must be related to me you might even think that there is a divine entity that controls everything that happens to you and then you realize that you're not really center stage that there are lots of other things happening around you and so as a civilization we would recognize that we are not also at the center of the living universe in my view that we are not special in any way and that's what I try to advocate to my students freshmen students at Harvard they come with high self esteem and I try to say that by looking at the sky you should develop a sense of modesty because there are more planets like the earth in the observable volume of the universe then there are grains of sand on all beaches on earth and moreover we live just for a percent of a millionth of the age of the universe so how dare we be arrogant that makes no sense but if you look at the history of humans you find Emperor's or kings that boast it after conquering a piece of land on earth since there are so many earths out there the situation is similar to an ant hugging a single grain of sand on the landscape of a huge beach nothing to be proud of it's quite actually you know it's quite ridiculous for an emperor King to be proud of himself and usually these were alpha males as you can see from the previous image but to me the more interesting question I mean it seems quite obvious that we are not special and that we should develop a sense of cosmic modesty but the second question that arises if we are not special are we the smartest kid on the block and that's what my girls tried to figure out and if I had to guess I would say probably not you know the earth formed life out of the ingredients that existed on earth by some random processes and if you open a cookbook you realize that out of the same ingredients you can make very different cakes depending on how you mix these ingredients together in what order how much heat you apply to them and so forth and so you can imagine other earths producing different types of life and I have no pretension to believe that life on Earth is optimal in any way especially if you've you open the newspaper you see the politics of the day and you realize it could have been better right and so there might be cakes that were baked to taste better out there you know and creatures that are much more intelligent than we are or simply had more time to think about things and correct themselves and perhaps develop technologies that will take us a while to recognize and so it would be worthwhile to try and meet them and learn about them but what's most important is to be open-minded not to have a prejudice not believe that we know the answer before we actually look through our telescopes that means that's the mistake that philosophers made in the days of Galileo some of them refused to look through his telescope they said we don't need it we know the truth and unfortunately some scientists say the same nowadays they believe they know the answer before actually collecting evidence and my point is quite simple let's collect the evidence first science is about dance and let's not have prejudice in other words whatever technology we have in our hands right now let's use it in order to explore this question and this question is of great interest to the public but most of my colleagues put it aside as outside of the mainstream of astronomy and frankly I don't fully understand that because if the public is interested and you are a testimony to that fact and if the public is funding science how dare are the scientists say this is a question we don't want to address now they do that because they believe that it may actually look non-professional since there is all this literature of science fiction and are reports that are not standing up to the level of scientific scrutiny about unidentified flying objects but that doesn't mean that we should retreat to a position where we don't explore this question we're just ignoring this question is a sin to science because this is a fundamental question about the universe and we have a technology to explore it so how how can we avoid addressing it it's much more relevant to society than many other questions that scientists address such as the nature of the dark matter or extra dimensions or the multiverse things that will never be observed and are considered part of the mainstream even though we will perhaps never get data to test these ideas so instead of looking at the mirror and trying to guess what the answer is maybe we should go out to the cosmic street and just like my girls did figure out if we are the smartest kid on the block and in starting the search we should start nearest to us of course in our backyard now of course one way to start a search is to do experiments trying to create a synthetic life in the laboratory and there is a group here at Harvard that does that led by Jack szostak a Nobel laureate and of course if we create synthetic life in the laboratory that serves an important role of guiding us as to where to look because we can recognize whether there is only one recipe for making life the recipe that was developed by the earth or maybe there are many multiple paths to developing life and we can figure out which conditions could lead to life and therefore search for environments that support these conditions so that's one way to do it and in fact physics developed this way we first did experiments in the laboratory and then went out to the universe and lo and behold we found that the same laws of physics that we discovered in the laboratory hold on large scales and describe the universe as a whole which was remarkable I mean there is no reason why the universe should be organized in the same way that we discover in the laboratory you know there are lots of laws that try to tell people how to behave and people don't behave the same way so laws that prescribe human behaviors do not necessarily hold why would the laws of physics hold if we discover them in in our labs why should they hold on the biggest case but they do the universe is organized and in fact that that is the most remarkable fact I think about the universe that that pretty much obeys the same laws as we find in a laboratory so we can explore the living universe the same way starting with laboratory experiments but beyond that we can start to search in our backyard and so the closest detector to us is the Earth's atmosphere and an object that would come let's say from outside the solar system and cross the atmosphere of the earth could burn up these are called meteors and if they are big enough more than a meter in size then they behind a meteorite now all the meteors that were reported until recently were originated in the solar system but about a year ago I was invited to an interview in a radio station about a meteor that was discovered above the Bering Sea of the shore of Kamchatka in Russia and in educating myself about meteors I went online and I found this table of all the meteors the tabulates all the data on meteors over the past 30 years and that data was collected by US government sensors that are used for national security you can imagine what they're used for but they also record meteors passing through the atmosphere of a natural origin not human-made objects and so I asked an undergraduate student that works with me and by the way I like young people because they don't carry a baggage of prejudice they are not attached to their egos as much as my senior colleagues and they're willing to explore without prejudice so I work with undergrads as well and one of them is a mere Siraj and I told him look there is this data set from the US government why don't we check if there is any meteor that may have originated from outside the solar system by extrapolating its orbit and seeing if it's bound to the Sun if it's not bound to the Sun it originated from outside the solar system and he went on and we found one such object that was discovered in 2014 and this is the first meteor that was recognized as potentially being from outside the solar system the only problem was that the US government released information about its speed when it impacted the earth but did not provide error bars and the reason they didn't provide error bars in my view is because they were very small obviously for national security the detectors need to be very good but we're still in the process now of the paper that we wrote being refereed reviewed and the interesting point is that some referees objected saying that they don't believe the US government and therefore you know they cannot if there are no error bars reported they will not accept the paper for publication but the editor of the journal the Astrophysical Journal Letters have found an innovative way of approaching this issue by having a reviewer that has security clearance that could look behind the fence and check if indeed the data is reliable so we're still waiting for the vertical on that but at least without the error bars it looks like this object came from outside the solar system and it's the it's really the first documented object that originated outside the solar system and and frankly if such an object lives behind the meteorites or something this is our only chance of putting our hands on a piece of technology that came from outside the solar system from another civilization because it would land somewhere if we figure that it's interstellar in origin we can then go to that side and examine whatever fell so that's an interesting window towards what's going on outside the solar system we have to remind ourselves that actually going places going to another star takes a long time if you use the current rockets that we have and you want to reach the nearest star it will take a hundred thousand years the mirror star so that's roughly the amount of time that elapsed since the first humans left Africa so if you wanted to reach the nearest star now you had to send a spacecraft when the first humans left Africa it will only reach it now now the next place where we can search is the moon now why is the moon interesting for two reasons one the moon doesn't have an atmosphere so anything that impacts the moon will not burn up it will just land on the surface and that's why the moon has so many craters because everything falls on it nothing burns up in an atmosphere surrounding it and so in principle you can look at the surface of the Moon and search for material that came from outside the solar system and you can do so by identifying isotopes that imply that the material did not come from the solar system you can find the isotope ratio that is not that is indicative of material different from the material that made the solar system but moreover the moon also doesn't have geological activity the earth the surface of the earth gets turned around within a hundred million years so if there was another for example human species that was around a hundred million years ago and had computer terminals and everything it's all buried now inside the earth we will not find it in archeological digs but the moon does not have geological activity nothing turns around and gets mixed and so whatever landed on the surface over the past few billion years is still there and all we need is to establish a base and excavate have archeological sites on the moon and the moon acted as a fishing net that collected whatever landed on it so it's sort of like a mailbox that collects mail that was posted in our direction if we never check that mail we would never know that we received a message and perhaps the message is we exist you know then maybe there is some something that crashed on the surface that is technological in origin maybe there is some biological stuff that came from another planetary system we should just check and NASA initiated the program Artemis aimed at establishing a base on the moon beyond the year 2024 so this would be an interesting scientific goal to pursue on the surface of the Moon then if we go beyond that we can monitor objects that enter the solar system from outside and the first reported object was Oh mwah mwah and you can see the trajectory that it went through in the year 2017 so it was at closest approach to the Sun on September 9th but we discovered it only on September 19th after it already passed that point so it was sort of like having a guest for dinner at home and then you notice that guests late in the evening and this guest looked very weird but by the time you realize that the guests left out of the front door into the dark alley and you can't really find it anymore and that's the experience we had with Omaha now I followed the same practice as I do with everything all my research so a year ago when there was a report about hydrogen being much colder than we expect in the early universe I suggested maybe the dark matter has a little bit of electric charge a small electric charge that would cool the hydrogen early on that was a hypothesis that we published in prestigious journals like nature magazine or Physical Review Letters and there was not much faster rounded here in the case of Oh mwah mwah you know there were a lot of unusual properties that were identified so I followed the same practice and try to analyze them and make the most reasonable sense out of them but for some reason it got a lot of attention and so let me explain why this object was so unusual so first of all we didn't expect it to come I mean so a decade ago we wrote a paper where we estimated the abundance of interstellar objects and we didn't expect anything to be detected with the pan-starrs telescope that detected Oh mwah mwah it's a telescope Survey telescope in Hawaii that monitored the sky and looked for earth crossing asteroids those that are dangerous would like to know about any object that may hit the earth because we don't want to suffer the same fate as the dinosaurs right so we want to protect herself and so this telescope was monitoring the sky and found this object where we expected none to be found but more interestingly this object actually was at rest in the frame of reference of the local population of stars so if you take all the stars in the vicinity of the Sun and you average the random motion you get to the so-called local standard of rest and this object was at rest in that frame sort of like a buoy sitting on the surface of the ocean at rest and then a ship runs into it that ship being the solar system so we ran into it and that's a very unlikely situation moreover when we monitored its brightness this object tumbled every eight hours and it's brightness changed by a factor of 10 now it gets this object reflects a sunlight so that means that projected on the sky the area that the object has changes over eight hours by a factor of 10 meaning that it's either a very elongated cigar as depicted on the left here with an axis ratio of all the one to ten or it's a pancake and actually if you analyze the tumbling motion you recognize that that pancake is the more likely configuration so that's quite unusual because all the objects that we have seen before that came from the solar system asteroids and comets were at most with an axis ratio of one to three this one was one to ten or more you realize that even if you had a paper-thin object in projection you would think that it has some thickness because you never see it edge on now moreover this object did not emit any heat the Spitzer Space Telescope had extensive observation didn't detect any heat from it meaning that it was relatively small and very shiny it was at the upper end of the reflectivity of that we see from asteroids or comets and it was the size of tens of meters to a hundred two hundred meters we don't know exactly how big and finally most intriguingly it deviated from an orbit shaped only by the Sun's gravity now we see this phenomena with comets they are being pushed by the rocket effect of gases evaporating from their surface as a result of heating from sunlight but then you see a cometary tail usually these are dust particles water molecules that you see coming off the surface of the comet in this case there was a deviation the meaning that there was some push exerted on this object but there was no cometary tail we couldn't see any water molecules no carbon-based molecules no dust2 a very significant upper limit so in fact orders of magnitude below what we see for comets usually and as a result of deep observations with the Spitzer Space Telescope so we see the object deviating from its orbit there is a push on it but we don't see the standard cometary tail and then the question is what is pushing on it so I tried to think about it and the only thing that made sense is perhaps the sunlight itself reflecting off it is giving it an extra push but then you infer that if it's indeed a pancake shaped object it has to be very thin so it could be a sail a light sail and in fact we are trying to develop this technology nowadays and I'll mention it in a few minutes you can imagine a sail being pushed by light and for space journeys that seems to be a very useful technology because you don't carry the fuel with you and so we just made a suggestion in a paragraph in that paper saying perhaps it's artificial in origin and then that paragraph was read on CNN and in an interview and was all over the news and I really didn't now the attention from the media I found useful because I try to communicate how we do science so science most of the time is filled with uncertainty because you don't have enough evidence now the scientists will try to hide it they would say let's close the door stay in our ivory tower talk among ourselves and come out to the public only when we know the answer for sure because otherwise who would believe global warming now I say look at the populist movements these days they don't believe some of them don't believe global warming why because they say that science is an occupy of the elite why do they say that because we as scientists some of us closed ourselves in in a room and don't communicate to the public the scientific process and in fact most of the time there are multiple hypotheses put forward we just don't have enough evidence so we can't decide which one is right it's just like a detective story you have various suspects the police does it openly right so you have various suspects you try to figure out who is to blame we should be open about the process the public should know that we are uncertain because then we get more credibility it's not an occupation of the elite anyone can understand it you know when a plumber comes to fix a pipe in my home it's a simple process I look at it and I understand it the same thing is the scientific process you know you have evidence you're trying to figure out how to solve the puzzle just like a broken pipe I mean there is nothing different fundamentally about it and frankly I don't see myself different from the public I still see myself as the young kid trying to figure out the world making mistakes trying to put out conjectures so what's the problem you know we might some of us might be trying to maintain an elevated image of ourselves in pursuit of Awards public recognition you know it's good for our ego but the scientific process fundamentally is about eliminating uncertainties by evidence and sometimes being wrong you know Einstein was wrong towards the end of his career he's argued that black holes don't exist gravitational waves don't exist quantum mechanics has spooky action at a distance he argued that makes no sense he was wrong whenever you work on the frontier you can be wrong there is a lot of uncertainty the evidence is not clear so that's part of the scientific process let's not be argA let's be modest once again modesty is a very good virtue because it allows you to venture in directions that discoveries if you always want to maintain your public image you don't want to make mistakes you never venture in those and and frankly the business world recognized that fact so venture capitalists invest in risky propositions why do they do that because one one of these risky propositions may turn out to work to be profitable and then it would pay for everything else for all the other mistakes that are being made and so in science it's the same way we don't know in advance what will bear fruit and we should allow ourself to make mistakes so at any event the bottom line is this object could be of artificial origin we just didn't have enough data let's continue to look for objects like it and let's not be afraid to discuss this I should say that there were a few scientists that tried to explain the same facts in a mainstream way but even those explanations were extremely exotic for example they argue that perhaps who moi moi is a fluffy object that on average has a density less than the density of air so that sunlight can push on it to me that sounds even more speculative imagining a cloud of gas being pushed by sunlight of 100 meters in size how does it maintain its integrity as it rotates every eight hours others suggested maybe we don't see the gases the outgassing because it's made of hydrogen ice which can easily evaporate at about 15 degrees above absolute zero so we've never seen a sight producing hydrogen ice that survives through a long journey through the interstellar medium that's also speculative but we should put all possibilities on the table and the next visitor weird visitor that we see coming to our dinner next time around you know we should look at the more carefully and not rely on prejudice now there was a second interstellar visitor that was discovered just a month and a half ago by a Russian amateur astronomer he built a 65-centimetre telescope and was looking in the direction of the Sun you might ask why would you look in the direction of the Sun well that's the place nobody looks at so he had a chance to discover things that nobody discovers another possible reason is that it's the place where you can see the glint from satellites if you want to find satellites but at any event he discovered this this object that looks like a comet so this one which is also interstellar definitely interstellar it's moving too fast to be bound to the Sun this one shows a cometary tail so I was immediately asked well if this one shows the cometary tail and it looks as if it's just like a solar system object of natural origin wouldn't you conclude that omoi was natural and I said you know if you go down the street and you see a weird person and then that is being followed by a lot of normal people that doesn't make the first person normal right so the fact that we see this object as being a typical comet means that Oh moi moi was even more unusual why was it so different and actually in the first date when I met my wife she looked special to me and since then I haven't met anyone like her so I have a personal reason to think that you know meeting and unusual having an unusual encounter can stick around you know another way to find interstellar objects is by searching for objects that passed very close to Jupiter for example and received a kick so that they became bound to the Sun after that the kick originates from the force of gravity exerted on the object as it passes close to Jupiter and so there should be a collection of objects that were interstellar in origin passed very close to Jupiter within a few times the size of Jupiter and were trapped in the solar system so in this case Jupiter and the Sun act as a fishing net that collects in the stellar objects and how would you find them well if they're interstellar they do not lie preferentially in the plane that characterizes the motion of all the planets all the debris of material from the formation of the solar system occupies a plane because it was made out of a disk of gas that circled the Sun and fed the Sun and the debris from it made the planets and the asteroids and everything else so most of the objects you find that were born in the solar system are in the same plane especially close to the Sun there were some that were kicked out during the history but if you find those interstellar objects they come from random directions so they have very high inclinations relative to that plane and that's one way to identify them objects that move around in the vicinity of Jupiter and for example rotate in the opposite direction to the orbital motion of the planets or go at a very high inclination relative to the planetary plane so that's another way and we estimated how many of those should exist based on the discovery of Oh mwah mwah and estimated that there should be a for the 6,000 of them so we can look for them and then the advantage of having them bound to the Sun is that we can visit them we can explore them more carefully in difference from Oh mwah mwah that is on its way out and we can never chase it we can never reach it with convention Rockets it's just moving too fast and also finding it would be really difficult because by now it's extremely dim so if you were to design a mission that will chase a it needs to be equipped with a big telescope and even then it's not clear that you would find it so potentially some of these objects could have brought life to the solar system by the way they could have transferred life to the solar system now going beyond primitive life you can ask what signs of intelligent life can we find out there and the simplest thing you can look for is artificial light so an interesting question to ask is suppose you have a city like Tokyo far away how far can you see it with the Hubble Space Telescope the answer is you can see Tokyo from the edge of the solar system so with the Hubble Space Telescope nobody mentions that because nobody thinks that it's plausible to have a spacecraft which produces as much light as a city of Tokyo but something to keep in mind because maybe maybe one of the lights that we see out there with the Hubble Space Telescope is associated with an artificial origin how would you find out well if you see an object moving away from us as its distance increases there are two possibilities it will get fainter either because it reflects sunlight so as it goes farther away it intercepts less light so the amount of light impinging on its surface drops as one over distance squared and then the amount of light that we see drops by another factor of 1 over distance squared so altogether is 1 over distance to the fourth so objects that reflect sunlight like asteroids for example they become dimmer as they move away from the Sun like one over the distance to the fourth power very quickly that's why Oh mwah mwah became very dim very quickly we can't see it anymore but an object that produces its own light like a spacecraft or a city only suffers from one factor of one over distance squared so it dims more gradually as it moves away from us so we can tell the difference between an artificial source of light and an object that simply reflects sunlight when I asked an astronomer that discovered most of the objects in the Kuiper belt in the outer solar system I asked him did you ever check if any of them dims with distance as it changes its distance from us where they deems as 1 over distance to the fourth one of a distance quad he said why should I check it's obvious it must be one of the distance to the fourth there is no point in checking once again having a prejudice in a way helps you to maintain your image but perhaps makes you at the same time avoid a major discovery as I often say extraordinary conservatism leads to extraordinary ignorance that's a paraphrase on what card second set he said extraordinary claims require extraordinary evidence I don't think so I think extraordinary claims require as much evidence as ordinary claims now if we now venture outside the solar system you can see here all the planets the earth and then 10 times farther away is Saturn a hundred times farther away from the Sun is where the solar wind meets the interstellar medium it's called the heliopause but that's not the edge of the solar system there is the so-called Oort cloud of objects that were kicked into a sort of spherical shell surrounding the solar system by Jupiter and they go all the way out to a hundred thousand times the distance between the Earth and the Sun roughly halfway to the nearest star so the nearest star if it has an odd cloud the - or clouds are touching each other the the nearest star system is Alpha Centauri it has three stars in it one of them is a dwarf star called Proxima Centauri and the other two are stars like the Sun most of the stars in the Milky Way galaxy are dwarf stars just like Proxima Centauri there are about a tenth of the mass of the Sun the Sun is not a typical star a typical star is Proxima Centauri and such stars like Proxima Centauri live for a thousand times longer than the Sun the reason is they're smaller even though they have less fuel to burn and by the way stars are just like nuclear reactors they burn nuclear fuel but they're held together by gravity nuclear reactors are held together by solid material you know but a star is like a nuclear reactor held by gravity so that's what the Sun is so these dwarf stars are smaller in size they have less fuel but they burn more slowly so they would last for a thousand times longer than the Sun when the Sun dies we might want to move to a dwarf star like Proxima Centauri which is next to us right now for the next few million years before it passes away but there would be another one now a couple of years ago a planet was found next to Proxima Centauri it's called Proxima B and amazingly enough this planet is 20 times closer to the star so even though the star is fainter than the Sun it so happens that this planet is much more closer to the furnace so that the temperature on its surface is roughly the same temperature as we have on earth so in principle liquid water may exist on its surface and the chemistry of life as we know it here is an habitable planet next door to us and the fundamental question is does it have liquid water does it have an atmosphere in order to have liquid water you need an atmosphere because solid ice when you warm it up in vacuum goes directly into gas phase in order to make liquid water you need an external pressure of an atmosphere so this planet is so close to the star that in fact it always faces the star with the same side it has a permanent dayside in a permanent night sight and my daughter now she's 14 years old but a couple of years ago when I told her about this discovery and I said look the there is this planet that we can move to when the Sun dies you know we might want to go there because the star would live a thousand times longer and it has a habitable planet next to it she said if we ever moved there I would like to have two houses one in the permanent night side where I would sleep and the second one in the permanent sunset strip that separates the night side from the day side where I would like to have my vacations and she had this idea when we visited Hawaii because you know the sunset is beautiful but imagine having having that view for the rest of your life you know the forever so real estate value must be very high and that's for the real estate agents in the audience on this trip now what we can imagine is only life as we know it in other words the chemistry of life in liquid water which requires an atmosphere and the warning sign comes from Mars Mars is a tenth of the mass of the Earth and it used to have an atmosphere so it may have had liquid water on its surface there is some evidence that perhaps it had but then at some point early on it lost its atmosphere and therefore lost its ability to maintain liquid water on its surface so we don't see any animals crawling on its surface that's a warning sign that without an atmosphere you can't have life as we know it the interesting question is does Proxima B have an atmosphere and there is a simple way to tell because if you have bare rock circling the star the permanent dayside will be heated to a high temperature and we can calculate the temperature contrast between the permanent dayside in the permanent night side the night side would be called and the day side will be hot and as the planet moves around the star we can see the color of it changing with time periodically we see more of the illuminated phase Minette moves at some phases of its orbit and more of the dark side at some other phases of the orbit just like with the moon and so without even resolving the planet just looking at the light curve during its motion around the star and by the way it takes 11 days for it to go around the star so a year is 11 days and if there is anyone out there they celebrate a birthday every 11 days it's quite they have a lot of parties so we can tell whether there is an atmosphere on the planet by comparing what we expect for bare rock to what would happen if you have an atmosphere that moderates the temperature contrast between the day side and night side either an atmosphere or an ocean that would try to equilibrate the temperature contrast between the two sides we can tell the difference with the upcoming James Webb Space Telescope we show that in a paper a few years ago this telescope is the successor to the Hubble Space Telescope and is expected to be launched in a couple of years year and a half there are other stars nearby that have planets around them some of which are in the habitable zone another dwarf star so Proxima Centauri is 12% of the mass of the Sun this one is 8 percent of the mass of the Sun it's called Trappist 1 and it has seven planets three of which are habitable just like the earth and of course we would like to know this this one is 10 times farther away than Proxima Centauri we would like to know whether there is life on those planets clearly earth is our home but only for a while because there are many risks that we can imagine there are internal self-inflicted wounds that we can imagine as a result of not preserving our climate as a result of nuclear chemical or biological war that would eliminate life as we know it but in addition there are external threats an asteroid can impact the earth if it's big enough it could damage prospects for life there could be solar flares affecting technological equipment just a hundred and fifteen hundred and sixty years ago that was the so-called Carrington event that was recorded and it was a flare from the Sun that hit the earth and at the time raised the temperature of the atmosphere by a few degrees but there was no technological infrastructure back then if it would have happened today and in fact a few years ago there was an event like that it just missed the earth if it would have hit the earth the damage to the infrastructure of satellites and power grids and so forth would have been in the tree of dollars something that we are not thinking about very often now if we want to venture into space to move away from the earth since currently all our eggs are in one basket the earth if you want to spread the eggs such that you know if something bad happens on earth will still maintain the future for our civilization we want to go into space now there is an interesting calculation that you can do right now we're on the surface of the earth we are held down to earth with an acceleration gravitational acceleration of 1g that's simply the force that keeps us stuck to this auditorium right the force that pulls us towards the center of the earth 1g you know that fighter pilots when they maneuver they can sustain up to 10 G but that's the maximum acceleration so it's much more comfortable to feel the acceleration of 1g and Einstein taught us something very important he taught us that gravity is not really a force that in fact if you were to go on a spacecraft that accelerates it would feel just like the force of gravity doesn't matter if you are accelerating because of an engine or because of gravity so in fact if we were to bore the spacecraft that accelerates that increases its speed by 1g it would feel just like sitting in this auditorium nothing unusual it would feel very comfortable now if you do that for one year the spacecraft would reach the speed of light that's a very high speed that's the high speed we can reach if you do that for 25 years continue to accelerate and and get closer and closer to the speed of light you can traverse the entire universe how can you do that the universe is tens of billions of light-years in size it continues to expand you can do that because of another effect that Einstein realized recognized it's called time dilation time is ticking more slowly when you approach the speed of light so within your lifetime within 25 years or so you can traverse these billions of light years if you were to continue to accelerate at 1 G the only problem is there is no such engine that can push you at 1g for so long because it needs an amount of fuel that is impossible to arrange but this is just a thought experiment now if you are not that ambitious and we want to reach but nevertheless we are ambitious and we want to reach the nearest star within our lifetime what speed do we need to move at about a fraction of the speed of light if you want you know if you are 57 years old like myself you want to do it in 20 years and that means that you need to move at a fifth of the speed of light because the nearest star system for example Proxima Centauri or the Alpha Centauri system is about 4 light years away so moving at 1/5 of the speed of light would get you there in 20 years can we reach 1/5 of the speed of light well Rockets carry their own fuel so they are limited by the speed at which the gas leaves their exhaust they are based on the same principle as jet planes you throw material backwards and that pushes you forward that's all that's how Rockets operate when you board a plane in Logan Airport that's how the plane brings you to your destination it throws things backwards and moves forward that's all now the problem with that method is you are pretty much limited by the speed at which you throw things backwards because you're carrying your fuel with you so if you throw a lot of fuel and you the payload is very small in weight relative to the fuel you can maybe reach ten times the speed of the fuel has when it leaves your your jet through the exhaust but that's thirty kilometers per second which is a percent of a percent of the speed of light for conventional rocket fuel and that's why all the Rockets that we launched into space since Sputnik two new horizon always reached that limit of about 30 kilometers per second not much has changed since the days of one Brown because you have to carry the fuel with you now a different technology is a light sail where you are pushing a very lightweight sail with light and you leave the fuel behind and this concept was envisioned by Robert forward back in the early 60s soon after the laser was invented here he argued that perhaps you can use very high power lasers to push on a sail so that it reaches a fraction of the speed of light and the approach is very similar to the sail of a sailboat except the sailboat is being propelled by wind gas molecules bouncing off the surface in the case of a light sail it's the particles of light that are reflected off and giving it a push and since you are reflecting light you can in principle reach the speed of light and this is a brief history of myself I was born 1962 in a small village in Israel I used to collect eggs every afternoon I grew up on a farm when I was up for tenure at Harvard I wasn't very worried about it because I always Plan B I would go back to work in the farm and frankly nowadays they sometimes contemplate that idea because it's a much more relaxing lifestyle to be closer to nature than with some of my colleagues but at any event this is me on the tractor with my two sisters and then we established a family here I was tenured at Harvard this is my wife and two daughters and then one day in May 2015 an intrapreneur from Silicon Valley named yuri milner came to my office at Harvard and said it was a black limousine that parked in front of the our building he came out he entered my office I didn't know what it was about and then he said would you be interested in leading a project whose goal is to reach the nearest star within our lifetime and it didn't take me much time to say yes and within six months we recognized that indeed the technology of a light cell is the best approach for that purpose for the reasons that I mentioned before and we announced this project called star shot with Stephen Hawking that came for the occasion so here is an illustration of the concept the idea is that there is a collection of small low power lasers which produce their own beams and the beams combine to a very powerful laser beam and then above the atmosphere there is a mothership that releases a sail and it's above the atmosphere so that friction with the air would not suppress its motion and the laser beam is pushing on the sail which has roughly the weight of a gram or so and it's equipped with electronics that includes a navigation device communication device and a camera and that can all be packed into one gram we have this technology in our cell phones and then within a couple of minutes this 100 gigawatts laser beam pushes the sale of one gram to 1/5 of the speed of light at that point the sail travelled a distance which is five times the distance to the moon we can focus the light only out to that distance and then we let the sail continue on a straight trajectory from there in the direction of our target eventually in the direction let's say of Proxima B so that it can take photographs tell us if the planet has vegetation on the surface or oceans or maybe it's a desert and send those photographs back and of course it takes four years for the information to get back so all together 24 years it's a long time but that's the concept we came up with and the way I view it is as sort of a sketch of what the technology might be like we have to work on the many challenges that are involved and that involves developing the photon engine the the light that is pushing on the sail and then developing a strong enough sail that is very highly reflective that doesn't absorb much of the light and worrying about risks from for example impact of dust particles whenever a dust particle impacts it's like a small nuclear explosion because this sail is moving at 1/5 of the speed of light there is a lot of energy being released at every impact and then of course the challenge of communication which is non-trivial and finally I'm told that it's much more challenging to worry about the policy issues than about physics especially when you have a technology that can be used for other purposes just to give you an example a dust grain can cause some damage on the surface of the space graphic creator but if you quote the electronics with millimeters thick material then in principle that would prevent the damage that could be substantial for not allowing the electronics to function and so our plans are for the next decade to demonstrate the principle by having multiple experimental teams exploring the technologies that are involved and then if it all looks promising dedicate the next decade after that to the construction of a prototype eventually constructing the full system which could cost as much as the biggest science project that we have like the Large Hadron Collider and it will involve funding from federal agencies in addition to private donors but as of now euro Milner is committed to fund this first step in principle we can imagine that other civilizations develop this technology already so how can we search for signals related to it well we can look for leakage of the light beam around sales that are launched by other civilizations so you can imagine for example a system that transfers cargoes between an earth-like planet and a Mars like planet so when the two planets align along our line of sight we would see the beam of light in our direction the leakage from that so we can search for flashes of light and it will be a flash of light because the orientation will be preserved only for a limited amount of time due to the motion of the star the host star in our motion so we will see a flash of light on the sky and one can search for it we do see flashes of light in the form of fast radio bursts the most popular view is that they are associated perhaps with newly born neutron stars neutron stars are stars that weigh as much as the Sun they were formed as a result of the collapse of the core of a massive star to a density that is similar to the density of an atomic nucleus so they have roughly the size of a city like Boston about 12 kilometers and the mass of the Sun these are neutron stars and when they are born if they possess a very strong magnetic field they could produce very bright radio bursts at least that's the conjecture for the origin of fast radio bus but we don't know and make perhaps a subset of the fast radio bursts that we discovered over the past decade are due to propulsion systems of the type that I described you can imagine that advanced civilizations migrated away from their home planet so in fact we send out Voyager 1 Voyager 2 New Horizons that will leave the solar system and as biological creatures we are not well suited for space travels so it's much more natural for us to send technological equipment electronics that is designed to withstand the harsh environment of space being bombarded by cosmic rays and so forth and so we might as biological creatures we might stay on this planet but we can send out robots that are equipped with artificial intelligence and with 3d printers so that they can produce whatever we want on the target planet out of the raw materials that are there so if we have for example a blueprint for how to produce life as we know it based on synthetic life that we produce in the laboratory we can send that information to the system that will use the raw materials on the planet to make life as we know we don't need to take precious creatures like our friends and send them into space in you know there might be some people that would like to do that just like you know in western movies you see all these very strange people that are willing to take a risk and die and but there is no reason for that if we have the technology to produce whatever we appreciate here on earth to produce it elsewhere there is no need to send biological creatures out there and it's quite likely that advanced civilizations and by the way if we ever encounter technologies or equipment even if it's defunct from advanced civilizations I think it would be shocking for us because it's much more likely to be far more advanced than our technologies our technologies are evolving on a three year time scale exponentially right now the car that I'm driving is far breath better right now then the cars that I drove a decade ago and you know a hundred years from now who knows how technology would look like so if we see something that is let's say a billion years old technology it would look like an approximation to God it would do things that we can't even imagine we would treat it just like a caveman treats a cell phone a caveman looks at the cell phone and says well I've seen rocks of all types this is a very special rock you know it's very shiny that's what some people said about more more for example there might be a lot of traffic out there in interstellar space and we just don't know because star shot like probes would not be recognized by existing telescope we won't see them they are too small our telescopes cannot see such things so there might be out there but we just don't know and you know civilizations might send out these things to places that have most resources for example clusters of galaxies you know the universe is expanding but it's not just expanding its expansion is accelerating with time so in fact everything that we see away from the Milky Way galaxy other galaxies eventually will run away from us at a speed larger than the speed of light we would never be able to chase those other galaxies and we will be left in our own galaxy so if you think about it and you want to maximize the amount of resources that you have in a distant future then you want to be in the place where there is the most resources and a cluster of galaxies represents that it has typically a thousand galaxies in it so that the place you want to migrate into it's just like migration of civilizations to banks of rivers you know in the ancient times and so the same thing might happen in the universe we just don't know if it happens right now now Enrico Fermi is a very famous physicist and he once had the lunch with colleagues with his group and they were talking about the search for extraterrestrial civilizations and by the way I should say that you know 80 years ago this was a subject that was discussed by the the most you know prominent minds in fact Winston Churchill in 1940 wrote an essay about the likelihood the fact that it's very likely that extraterrestrial civilizations are out there and that was just before he became prime minister and then of course I mean he didn't have time to publish that essay but it was discovered so Enrico Fermi discuss it with his research group it was a very mainstream physicist and then he said wait if it's likely they are out there where is everybody why don't we see them and that remained as Fermi's paradox and in my mind the most likely explanation is they are short-lived once they developed they developed the means of communication that they developed their technologies to the level that exceeds the technologies we have right now they also developed the means for their own destruction you may call it the brexit factor so it might well be that there were a lot of civilizations out there but they are dead right now but that doesn't mean that that explains why we don't see signals from active civilizations if they are short-lived but it doesn't mean that we can't search for relics that they left behind in fact the whole field of archaeology is based on that right you dig into the ground and you look for evidence for ancient cultures that do not exist anymore and you can do the same thing in space I call it space archaeology so we can look for signatures of dead civilizations we can search for burnt up pay surfaces of planets that went through a nuclear war we can search for atmospheres that have industrial pollution we can search for relics in the form of technological equipment that is flying through space from that is dysfunctional defunct but represent the civilization that existed a while ago and it doesn't need to be on other planets these dis relics may be floating in space so my hope is that this will serve as an important history lesson for us because if we find evidence for dead civilizations and we can identify the reason that they are dead be it due to a war or because they didn't take good care of their planet some bad politics then it will teach us a lesson to get our act together and behave better so that we will not share the same fate we can search for technological artifacts so for example if a planet passes in front of its star we can examine the composition of the atmosphere we can search for oxygen that may indicate primitive life microbial life but we can also search for industrial pollution now industrial pollution could be intentional if the planet was too cold to start with you might want to cover it with a blanket of gases that are artificial that will warm it up you can look for the reflectivity of photovoltaic cells that cover for example the permanent de side of Proxima B in order to generate electricity on the permanent night side of Proxima B so you can look for the reflectivity of those photovoltaic cells there is a tidally locked planet as the planet moves around the star you would see the special signatures of an artificial coating like a photovoltaic cell solar cell which is very different than the reflectivity of vegetation vegetation has a so-called red edge leaves of trees they reflect red light infrared light because it cannot be used for photosynthesis the only consumes consume ultraviolet radiation optical radiation it's used for photosynthesis the infrared radiation is garbage so it's being reflected and when you look at our planet from a distance you see evidence for a red edge a high increase in reflectance infrared radiation if the planet was covered instead of by vegetation if it was covered by photovoltaic cells the reflectivity will change at a different wavelength and you can look for that finally I would like to mention this anecdote that in fact when you look at your wedding band if it's made of gold you might wonder where did this gold from well we now know the answer we figured the answer only a year ago astronomers figured it out the LIGO experiment that detected gravitational waves for the first time a few years ago and for which the Nobel Prize was awarded a few years ago discovered the merger of two neutron stars and the gravitational waves the ripples in space-time that were generated as a result of the merger of two neutron stars was followed by the emission of light and from analyzing this light astronomers were able to deduce that heavy elements like the gold that we have in a wedding band were most likely produced in such events when two neutron stars collide a little bit of the neutron matter is expelled into space and then it decays because it's not stable it decays into heavy elements like gold and uranium very heavy elements so next time you look at a wedding band remember that this material was produced as a result of a violent collision of two neutron stars stars that weighs much as the Sun roughly the size of Boston that's where it came from now both uranium and gold are the sources of evil here on earth right so you might say well if there is a neutron star neutron star collision somewhere in the galaxy planets that are close to that collision site will have a lot of gold and uranium we better be careful because you know they might have a lot of nuclear weapons out there one thing of course is that once you have too much gold it's not worth much you know so I mean it's good to a limit to get more gold but beyond a certain amount the value will drop so anyway things that we find as precious rare elements really are rare because we are relatively far from a site of a neutron star neutron star merger something to keep in mind when we move around the galaxy you know we might go to places that have more of these and actually molybdenum is another element produced in such collisions and that's important for life so my hope is in summary that if we ever venture into the galaxy into interstellar space we will see a lot of traffic out there and we'll hear a message back saying welcome to the interstellar Club thank you thank you for informing and kind of blowing my mind a little bit there I didn't know so we have a few minutes up we'll try and get through a couple of these and then we do invite you to continue the conversation downstairs and the reception but we're gonna start we're gonna go a little deep given that life in other places might be similar or very different than life on Earth how do you define what life is is there a gray area that's an excellent question in fact I wrote a textbook about extraterrestrial life and first together with former postdoc of mine - Willingham and the first question that we try to address is the definition of life and of course it's difficult to define it because all we can talk about these life as we know it and there could be many other forms of life now what do we mean I mean there are some characteristics of life that we are familiar with that something that can reproduce itself that can make copies and that can maintain some activity but you know we will know it when we see it okay and and we pretty much recognize what life is on earth so the idea is if we see something unusual on the surface of another planet by visiting the surface we could examine it well enough with our scientific tools to tell us if its life and and the fundamental question is is it life like we find here on earth if it looks just like the life we have here on earth it might be that there is only one path to life one recipe in this cookbook and the other possibility is that life was shared between the place that we visit and Earth both of these are fascinating if we find life that is completely different then the DNA based life that we find on earth then it would be remarkable because that will open our eyes to a completely different path for life for other recipes and I'm sure there would be a lot of research on that and I should say that all of this research on the origins of life could have important implications for medicine because when we understand life we could develop ways to cure diseases and other issues with life and so I think like any other fundamental basic research this path of exploration offers a lot of promise for the future great and so the succession ties so obviously your comments when sort of hit the press it went viral I mean it went it farce to surpass just the Astronomy community and even the science community so if something artificial is discovered from interstellar space what do you feel would be the best safest way to tell us the public oh I think we should be we should immediately inform everyone frankly when people talk about conspiracy theories I don't think the government is that component to keep it secret so and I think sharing information is the best approach in science because different people can look at the same data and analyze it and figure out if it's real or not and in fact Steven Spielberg got the honorary degree at Harvard and after the ceremony I shook his hand and I told him that we are searching for the signals and things out there and and he said if you do find evidence please let me be the first to know about it but of course you know we will let everyone know about it wouldn't the digital AI is produced by an intelligent civilization far outlive the civilizations themselves so shouldn't we be looking for those yes in fact I would think that we should be looking for the things that are longest lived with which our technological in origin so we should look for equipment floating in space that's that will be my not when we do our archaeological dig into space I think we should think about mostly about artificial equipment the question is how to detect it and I mentioned a few ways and first our shot art ground-based lasers hindered by the atmosphere but a space-based light source be better such as focus sunlight or a space laser in principle yes the problem is that it costs a lot of money to lift things into space and moreover it's much more difficult to service them as we know from our experience that a telescope like the Hubble Space Telescope did cost us about you know ten billion dollars so you know having a lot of lasers out there that weigh much more than a single Space Telescope would be too expensive to maintain and so that's why we contemplated a station on the ground that is much more economic that you can service and also maintain and make sure that all the optics is aligned you can imagine robots doing it in space but they you know whenever we went through the numbers it didn't look real real speaking of the cost is exploration worth the enormous cost oh I definitely think so because we're talking about the the long-term future of our civilization and you know much of our activity if you think about if you boil down your life very often it has to do with your children you know just thinking about the next generation that's true as an educator you know for me educating the young generation of today is extremely important I have great faith that they would do greater things they would think more clearly about the important priorities then our generation did you know and that's my hope and and so when we always think about our kids you can think long term you can think about the kids of our kids and so forth and you know what's the long-term future for our civilization if conditions deteriorate here on earth we should think big we should think about going elsewhere we should contemplate going into space and that's obviously the place to go because you know earth our life on Earth is on a two-dimensional surface so most of the time when you open the newspaper it talks about what happens on this two-dimensional surface but there is a third dimension that carries a lot of information a lot of space out there that we that we could explore and why not there is a lot of real estate out there is sentience necessary for interstellar travel is there a mechanism by which a non sentient species or civilization could travel well yes nature mother nature itself produces spacecrafts that carry tiny astronauts for example we see on earth rocks that came from Mars how did they travel well they originated from an asteroid impacting Mars and lifting the surface layer of frog from its surface and kicking it into space and eventually some of these rocks landed here on earth and one of these rocks that was examined about two decades ago when people studied people at MIT studied the magnetic properties of that rock from Mars they concluded that it was not heated by more than 40 degrees to more than 40 degrees Celsius or more than 104 degrees Fahrenheit meaning that on its journey from the surface of Mars to earth life could have survived and so potentially if there was life on early Mars it may have come to earth perhaps it predated life on earth perhaps we are all Martians but it demonstrates an important principle that nature is often capable of doing things that we imagined as being our ultimate technological goal sending life into space on a spacecraft you know nature did it with rocks a long time ago and we actually wrote a paper just recently that we just submitted for publication this week with my undergraduate students showing that you know boulders that passed through the Earth's atmosphere could have been scooping life from the atmosphere of Earth and taking it out of the solar system so if there were tiny astronauts in the atmosphere of the earth in the form of microbes they could have traveled through the solar system into interstellar space long before New Horizons was thought of and so this will be our last question for now and again please join us at the reception do you have any advice for students applying to college who are interested in joining the search for extraterrestrial life and what are the best majors we have a student group in here I believe so yes definitely I think it's an exciting frontier for the future and the next generation may find the answer to many of the questions that I asked and the most important advice that I would give is don't listen to the adults in the room just do what you think is right based on evidence not on prejudice explore the unknown going directions nobody dare to go because actually it's you know going on the road not taken' is actually what's fun about life and that would be my advice do that and perhaps you will be the first to discover exit the rest your life thank you for being here we thank all of you for being here it's all I believe there may or may not be a book being written within as we speak Christmas in a year so you're here to hear first human eye out for that we hope to see you back here soon please join us downstairs thank you

Channel: Museum of Science, Boston

Views: 100,486

Keywords: Museum of Science, Boston, Science Museum, Boston Science, museum, Extraterrestrial Life, Harvard University, Avi Loeb

Id: uFrBcy0P6iM

Length: 91min 0sec (5460 seconds)

Published: Fri Nov 22 2019