Astrophysicist on God’s Equation, Dark Matter, and the Future of Life Beyond Earth | Alex Filippenko

i hope you guys enjoyed this episode brought to you by our sponsors at athletic greens to receive a free one-year supply of vitamin d and five free travel packs with your first purchase visit athleticgreens.com impact theory enjoy the episode hey everybody welcome to another episode of conversations with tom i am joined today by somebody that i've been waiting 30 plus years to speak to the legendary astronomer alex filippanko alex thank you so much for joining me well tom it's my pleasure and my honor you know you've done so much to impact people's lives in a positive way you know i've watched a number of your programs it's just been fantastic and you and i share a number of aspects of our lives in the for example we like to set goals we like to be efficient work hard be motivated know why it is we're motivated and so what you say to people resonates very much with what i've you know how i've conducted my life and how i try to inspire people as well wow man thank you for somebody who was on one of the teams i think there were 50 of you that essentially won the nobel prize i know it can only go to three people um but that you were on that team that's incredible man thank you you obviously have very useful goals so very excited to to sit down and have this chat and hopefully the next time we do it we'll be in person that would be amazing yeah i mean you know weird circumstances but i know that in the past year you've had a lot of practice doing these um you know skype interviews with people and they worked out really well it it's almost as though i'm there with you in person yeah it is uh the technology is a saving grace and when i think about the fact that this wouldn't have been possible if this had happened back in you know 2010 like this wouldn't have been possible so i know there are a lot of times when this could have occurred and been just disastrous even more so than it's been now so uh for that i will i will certainly tip my hat in gratitude so uh yeah technology has brought us together and here's something in fact that a lot of people may not understand about astronomy and i was saying before we started rolling that one of the things that um i was once asked what i would be if i wasn't an entrepreneur and i said an astronomer and admittedly that um is is accurate in terms of how astronomy makes me feel i'm way too bad at math to actually do it um but there's something about the the grandeur but the way that it's usable and when i heard that um the theory of relativity was necessary for gps to work that's when i was like wow there's a lot of things that we have around us that we take for granted that actually have to do with physics and people looking up at the stars and i wanted to start with what you teach in your basics of astronomy class you say there's like four or five things that you want people to learn and if they don't learn you're going to come back and fail them you know even if it's 20 years deep in their career what are what are those handful of things yeah you know one of them is that as carl sagan used to say we are made of star stuff and by that what he meant was that the heavy elements in your body the carbon in your cells the oxygen that you breathe and that's in water the calcium in your bones the iron in your red blood cells the phosphorus in your dna all those heavy elements were cooked up through nuclear reactions deep inside stars during the course of their normal evolution and also when they explode some stars explode and this debris goes flying out and mixes with other clouds of gas gravitationally collapses forms new stars they then go through the same process of what we call nucleosynthesis and then stellar explosion etc etc and after billions of years of evolution our galaxy the milky way galaxy had these clouds of gas that had a sufficient quantity of heavy elements that rocky earth-like planets could form and then somehow somewhere you know bacteria formed little singular cell organisms formed and through billions of years of evolution here we are sentient beings that can come to understand the process of our origins the origins of the very elements of which we are made if that doesn't grab you i don't know what will right that we're made out of atoms that were literally spat out of exploding stars yeah that one's interesting to me for a couple reasons one it gives you a sense of um this sort of star wars moment of a long time ago in a galaxy far far away that there were that we've sort of come along so late that stars formed and collapsed and exploded populated you know other places and then we ultimately come out of that it really gave me a sense of like what 13 billion years really is uh an extraordinary amount of time um well the other thing one gives it gives it a purpose to the universe right if the universe had only inanimate objects like rocks and stars and things like black holes it wouldn't be able to think about itself and reason through how it all came to be and how it evolved in a sense we are the way in which the universe is found to know itself and you know there may be others i don't know but we're the only ones the only sentient beings with this capacity to ask and answer abstract questions and that's just a marvelous thing how do you contextualize that like is it poetic for you is it religious like how do you make sense of that yeah you know it's some combination of poetic religious spiritual for sure uh you know we all try to find meaning in our lives and there are many ways one can find meaning but one way that i've found is to contribute in some small way hopefully a large way but at least in some small way to humankind's understanding of the cosmos of this amazing and magnificent universe in which we live and one thing i try to do in my semester-long course at berkeley is to show students not only the magnificence of the universe and its contents but that through this process of careful thinking observation experiments we can come to and have been coming to a pretty good understanding of how it all works there are a lot of things we still don't understand absolutely new things continue to be found i mean as a scientist it would get boring if there weren't new unexplained things to continually answer that's why i'm in it but we also understand a lot as well and you know testament a testament to that is the fact that we can build airplanes and rocket ships and pacemakers and and these electronic devices through which we can talk no matter where we are in the world right that's a testament to the success of science yeah it's it that when so i'm not a religious person but when i think about the relationship between the cosmos sort of how vast it is and how much there still is to understand and yet through the things that we've discovered so far how we're able to shape the world around us i'm obsessed with this idea that skills have utility and there's another way to say it would be knowledge has utility insights have utility and getting people to understand you don't read a book to check you know a box on the list you don't go to college to impress your parents you don't even look at the stars just to say that you can it's you're getting data back from that and that data then lets you do something and one of the like you talk about wanting to have an impact on people one of the things i want people to get is like when you learn about something you then can build a bridge erect a building create gps travel to the stars like it that fills me with wonder it feel fills me with a sense of agency and if you begin to tell yourself the right story then it becomes also meaning and purpose and like that's the juice and it's so crazy like when you look at the stars what do you feel i i feel basically all the things that i just said and i have such a hard time putting it into words but what do you feel when you look up yeah no actually i think you expressed it quite eloquently you know i feel a oneness with the universe that i'm part of this grand structure that evolved over 13 or 14 billion years and here i am a small subset as far as we can tell that that can strive to understand it you know and i don't have to be the one who makes the discoveries you know i'm an astrophysicist but i gain joy in learning what biologists have have determined you know the the human genome project crispr cast nine all these advances that can be amazing for the benefit of humans but also just intellectually so provocative so enthralling so ah inspiring right that we are these creatures that can come to this understanding and you know going back to something you said at the very beginning you know general relativity was this weird theory of warped space and time that some crazy hair you know theoretical physicist you know albert einstein of course dreamed up fast forward 50 years and even 100 years actually and here we have gps which with all of its military and commercial applications that simply would not work if you didn't take into account the warping of the passage of time depending on where you are in a gravitational field and an even better example is quantum physics you know a century ago physicists were thinking about the world weren't interested in making a better toaster or or improving cars or whatever there were two major questions understanding the nature of light and understanding the existence of atoms and you might think well those are just you know intellectual titillation it doesn't really matter but it does because fast forward a century and today's micro world the half a billion transistors at the head of a pin basically right moore's law all that that's built on an understanding of the quantum world the nano world you know these little seven nanometer pixels that are now infiltrating electronic devices and storage units and stuff that was all an unanticipated spinoff of sort of blue sky wondering about the world and our place in it and how it works so you know that's the best of both worlds we satisfy our intellectual curiosity and we do things that are for the benefit of humankind yeah it's a great way to look at it um as you were talking it made me remember something i've heard you say in interviews before that as your wife knows every now and then you sort of wake up in the middle of the night screaming that we may know nothing like like there might be some huge revelation coming that will show that we're sort of as both brilliant and ignorant as somebody like newton right who couldn't have conceived of what was to come and yet gave us these tremendous breakthroughs do you think because when i i can sort of grasp the big concepts of astronomy but when it gets down to the to the quantum realm i start freaking out in like a really fun way but like the double slit experiment in um in physics quantum physics particle wave look at don't look at and things change like that freaks me out in a way that i love so much and in science you often talk sort of the the miracle the the axiomatic part you get down to where it's like you just have to trust that this thing is real do you think there will ever be a point where there's sort of no more miracle to get to where we know like what the vacuum is made of or like i'm not even sure how to ask that question do we ever find the base it's a great question tom it's something that scientists and in particular physicists struggle with all the time the short answer is probably we'll never have such a theory and the reason is is that science and in particular physics is not so much after the truth with a capital t reality with an uppercase r but rather a description a quantitative description that allows us to explain quantitatively the results of experiments that have been done and to make predictions about the likely outcomes of experiments that have not yet been done to the degree that we can explain what's been done and make predictions that then get verified we pat ourselves in the back and we say we have a pretty good working model but we never know whether there will be some experiment in the future that does not conform with the predictions or expectations of our model of our description in that case it'll have to be modified sometimes in small ways other times in fundamental ways like einstein's relativity which was a completely different way of of looking at newtonian mechanics and then the quantum world you know that that deals with the very small and you have general relativity that deals with the very large if we someday have a quantum theory of gravity that's well verified and tested and explains situations where there's a lot of mass in a small volume we may pat ourselves in the back and say hey this is working we have the final theory but who's to say that some young whippersnapper someday won't find an experiment that doesn't agree with that and so a new modification will have to be made so it's always a description a model within the context of what our brains of k are capable of constructing it's unclear whether this is the underlying reality right yeah that that question to me is um too tantalizing to leave alone and i'm not sure why i find it so interesting because certainly somebody like myself is never going to make use of that knowledge it's just not what i've aimed myself at um but there is something magical to einstein's question of i want to know god's thoughts and everything else is just details what do you think about that like i think he had a comp well as we look back on his life i think we have a complicated relationship to what he meant by god um he may have had a very clear relationship but what do you think about a sentiment like that do you find that equally intriguing to you is that just not worth pondering yeah uh it's an interesting question because you know there are books of einsteinian quotes you know there's like a thousand of them or something he's a very quotable person and there's a mark a remarkable number of them in which he brings up god and this has led many people to think that he was a deeply religious person in the classical sense it's not true it turns out that his god was what's called spinosa's god it's sort of the god that that is nature that explains sort of you know the ways in which the natural world works it's sort of the god of the natural world he did not believe in the classical god who's sort of you know watching over things and maybe even you know influencing them along the way so when he said he wants to know god's secrets i interpret that to mean that he wants to know really to the degree possible what are the fundamental laws quote unquote for laws because even he admitted that these are all just descriptions and models but nevertheless the farther down the path you go the more complete you think your description or model is because it explains and is consistent with more and more observed phenomena and so we begin to think of it as being the reality even if deep in our hearts and of course i didn't know einstein but i speculate that deep in his heart he probably would have admitted that this isn't necessarily the reality it's just a description that happens to work really well and for example in a quantum theory of gravity you don't even have curved space time you have these little particles called gravitons that are zipping back and forth between say earth and the sun telling each other that we're here and for the earth to be gravitationally attracted to the sun and same thing with the moon and the earth whereas in his theory he thought of it as being the consequence of a curved space-time but that's just a description or a model that happens to lead to calculations that can be done relatively easily and whose outcomes can be compared with things like the orbit of the moon or earth okay but again it's just a model it's just a description and i think he understood that that's all it is but was hoping that through the end of this process we will someday know the final theory even if he perhaps didn't think that that was ever really truly possible there's a lot of interesting things around there so um one the reason i said that i've been waiting whatever 32 years for this interview is when i was a kid i was just unable to wrap my head around the idea of an expanding universe which i know is one of your areas of expertise because i just kept thinking all right hold on if you expand a city you expand it into the areas that are forest or whatever there was something there if you build a house there was land there before you built the house what is the universe expanding into even as you get into gravitational waves right like you imagine this thing going up and down what what's below it what was above it like i even now i'm like i don't understand how what what are we expanding into right so here's where i like to use analogies all right um first to answer your question there are two ways of answering it we aren't necessarily expanding into anything and i'll clarify that in a minute or you can think of it as expanding into a fourth spatial dimension so we have x y and z okay this would be a fourth dimension that we can't see we can't touch we can't experience it's mathematically describable but physically inaccessible okay can we before you move on can we describe what you mean by physically inaccessible are you saying that hey we've got eyes ears touched they we have an umvelt we have confused that umvelt with all things and once you get beyond our sensory perception because that was one thing i struggled with a lot until i came to understand sort of david eagleman's idea of you're just a mr potato head and you could read magnetic signals but we don't have those receptors a shark you know can sense magnetic uh or electrical movements so you can actually trick a shark i still can't believe this is true but i've seen the footage you can put a a plate on the floor of the ocean that has an electrical current that mimics the electrical current of a flopping fish an injured fish and the shark will just sit there attacking the plate all day long because it's actually picking up on the electrical signals that made me realize whoa like there is a lot of data that we just can't perceive and so because i know what you're about to explain uh is that what you mean by we can't perceive it it's it's beyond even that sort of perception you know the shark thing if we have the right sensors and scientists have done this this is how they know they can detect those signals even though with our eyes we cannot but there's all kinds of for example electromagnetic radiation light that our eyes don't perceive you know radio signals and x-rays and stuff what i'm talking about are actually other dimensions so here's where i like to use an analogy and you know a piece of advice i give to people to clarify your ideas with an analogy when you can so i'm gonna i've got this balloon here all right i anticipated this question tom and so i'm gonna suppose that this is a hypothetical universe where you're constrained to be on the balloon actually more technically within the rubber itself and you can only go forward and backward left and right and any combination of those two motions okay along the surface or or through the balloon the laws of physics prevent you light or anything else from going into the balloon or out okay by do you is there a known mechanism by which we are stopped well in this hypothetical universe no i'm just asking you to suppose it so in our universe the mechanism would be that all the particles light protons electrons are restricted to the usual xyz dimensions in this room okay and we're still trying to figure out why in string theory the reason is because every particle is a vibrational mode of a little package of energy called a string and the ends of the string are tied down they're anchored to this xyz space okay but whatever the mechanism you're restricted in this case to only being within the balloon now the balloon can expand and i forgot to bring my little stickers but in my classes i put little stickers on this and the stickers move away from one another and if you imagine a sticker is a galaxy like our milky way you would see the other galaxies moving away each of them thinks they're at the center but none of them is in the unique center the unique center is the center of the balloon right but that's not part of the universe as i've hypothetically defined it the universe is only the balloon the center is in a mathematically describable but physically inaccessible dimension and so too is the expansion i blow some more not too much otherwise i'll get a little bang a little bit of nerd humor there but it expands into this dimension that we can describe very easily mathematically okay the r dimension in polar coordinates but the dude in the in the balloon does not experience the r dimension outward or inward they only say we are at r equals six centimeters or whatever it is okay they know about are extending farther outward and inward at least mathematically they know about that but they can't actually go there or see it or anything like that so in that sense now take our three-dimensional universe think about a three-dimensional sphere not the inside of the sphere but something that wraps around a fourth dimension we're expanding into that fourth mathematical dimension even though we can't see it or even conduct any experiments unlike the shark case that show us that it's there okay does that clarify things a little bit for you that is extraordinarily transformative in my life and i actually mean that literally i now know why you have won so many teaching awards but now what you've done is simply give me the next question to ask which is extraordinarily powerful and what a gift but now i'm going to ask it and let's see where we go so the part about string theory really helped with the breakthrough in that there's something that we don't know yet that there's some force i'm going to use my language and if i misspeak please stop me but there is some as of yet unknown force that is anchoring us within the rubber of the balloon and that's really important for anybody who's not watching to to think about the universe being only that layer of rubber and your entire life is within that layer of rubber and there is a force as yet unknown that keeps us in that layer of rubber make sure that we can only see within that layer of rubber and even detect only within that layer of rubber so now my question is what what is that like so the r dimension and this is using analogy so i look up at the stars i have this sense of wonder and awe and it triggers in me and i don't know how much you um know about sort of the other side of my life but actually right and impact theory is meant to be a film tv studio the whole nine and i'm always drawn to science fiction because it you get to play the well what if it were like this game and one of the analogies that i find just absolutely exhilarating is uh and i had somebody tweet me this question to ask you is in men in black at the very end of the first one they do this pull out pull out pull out pull out until you zoom out far enough of our universe to realize that we're really just a marble in an alien universe and everything that we think of as is the universe in existence is you know this actually really really small thing and this idea of bubble universes where were there some greater which still doesn't answer the question of what but you know there's some greater thing holding this foam of bubbles in every bubble as a universe yeah that to me is i want that to be true so badly like there's just something about the the just it's so big and so unknown now let me anchor sort of where i'm going i read once that gravity becomes where everybody in the physics and astronomy community pay attention because it's the one sort of mysterious force and all the other ones make sense but there's something about gravity's too weak if i'm not mistaken can you explain that right so there's a lot to unpack there i mean right questions you know you should clone yourself and become an astrophysicist all right i'd have to get a lot better at math so first of all yeah the idea of multiple universes has now gained real respectability i mean card-carrying physicists astrophysicists are thinking seriously about the possibility because we could discuss this later on but ideas about how our universe was born and evolved with time naturally lead to other pockets that are essentially independent of ours and so there could be you know a gazillion of them there could be an infinite number of them okay so i'm you know i i like that idea a lot for a lot of reasons now getting back to your specific thing about gravity yeah if you look at the four fundamental forces of nature there's two nuclear forces that keep the constituents of protons and neutrons together and they keep protons and neutrons together in a nucleus that's called the strong nuclear force then there's a thing called the weak nuclear force which sort of keeps the neutron together in a sense then there's electromagnetism which keeps the electron and a proton in a hydrogen atom together and then there's gravity which keeps us to the surface of earth when you look at these four forces in terms of their natural strengths relative to one another gravity is like 38 orders of magnitude 10 to the 38 power weaker than these other ones which you know they're not all exactly the same but at least they're comparable to one another but gravity is like 38 orders of magnitude weaker than electromagnetism which is to say that the electron and a proton in a hydrogen atom feel essentially no gravitational force they are completely and utterly dominated by the electromagnetic force well a big question is why is gravity so weak and one idea is that although the particles i described in string theory are these little open-ended strings that are tethered to the rubber that we just talked about the carriers of gravity these gravitons are thought to be loops and they can escape from this rubber balloon and go floating off into that other dimension which is called the bulk bulk this is like a membrane a brain in the bulk and there are other membranes elsewhere but if most of the gravitons are floating around in the bulk then there are not many of them in the membrane that is our universe that's one idea of why gravity might be so weak and so those those gravitons would actually be having an impact in our membrane or no um not really except that the corollary of what i just said is that gravitons from other universes in this bubble theory could reach and get into our membrane and that might be one way of testing for the presence of these other universes which at this point are completely speculative it's an interesting idea that seems to fit well with a lot of our other ideas but there's not a shred of direct evidence for these other universes but this might be a way of finding that evidence if someone were to someday directly detect gravitons and find some way of figuring out whether they came from our piece of rubber or some other piece of rumor somewhere out there i don't know how you would do that but it's within the realm of speculation at least is anybody asking the question around whether we could ever like us as a whole human being or even with an instrument but sort of rip through the membrane and exit out into the i forget what you just called it but that other space the what the bulk a bulk yeah so has anybody speculated can we theoretically cross into that region yeah um great question black holes which are regions of space where matter is compressed so much that nothing not even light can escape okay can be thought of as rips in the fabric of space-time because they end up with a singularity either infinite density that is you know a finite amount of matter in zero volume or if you bring in quantum physics maybe it's just a very very high density you know but not infinite but in any case it's definitely a weirdness in our otherwise smoothly varying space time and the equations even suggest that on the other side of the black hole in our universe it opens up into another black hole in one of these other universes or in a very distant part of our universe and so if we could find well if this is true this hypothesis and if we could find a way to hold the throat of the black hole open so that we could safely pass through there might be a way of actually experiencing that is getting into or at least getting information from these other universes again this is highly speculative but these would be essentially rips or wormholes in space that give us access to other universes very highly speculative now this is this is the stuff i i absolutely love so let's play with the speculation for a minute so um one there's a few things around this i've always been super curious about forgive me for asking sort of rudimentary questions what is it about so you talked about the throat so i know there's um probably a gravitational effect that as you cross the event horizon would just rip you apart because your your toes would be more impacted by gravity than your head and so you would just literally disintegrate so i understand that but um what then if we talk about opening the throat are we somehow stopping that that gravitational um discrepancy like what what do we mean by holding it open yeah okay so the effect you're describing uh of being ripped apart is affectionately known by astrophysicists as spaghettification because you get stretched in the long direction and squeezed in the you know along your width uh that actually happens for a relatively low mass black hole maybe 10 times the mass of our sun it indeed happens outside the boundary the so-called event horizon of the black hole and you'd get ripped apart but it turns out for gigantic black holes a billion times the mass of our sun like the ones that exist yeah pardon that exists yeah yeah you know um in april of 2019 just two years ago the event horizon telescope team showed using a bunch of radio telescopes on different continents they showed this amazing picture of a black hole in another galaxy actually the silhouette or the shadow of a black hole since no light comes out of a black hole you can't actually get a picture of the black hole but this is the silhouette of a black hole and it's in a galaxy called m87 55 million light years away which means it took light you know 55 million years to reach us but that corroborated the evidence we have from other lines of reasoning and measurement that these black holes really do exist in the centers of galaxies and our own milky way galaxy has a black hole roughly four million times the mass of the sun and that was in fact that discovery was recognized with the nobel prize in physics just last year in 2020 to two colleagues of mine reinhard guenzel here at berkeley and in germany and andrea gaz a colleague of mine at ucla her team and guenzel's team showed really clear evidence that our milky way galaxy has one of these so-called supermassive black holes so for the supermassive ones you actually don't get ripped apart just outside the event horizon the boundary you get ripped apart when you're closer to the singularity to the middle but regardless the worst ripping apart and then squishing together occurs at the center the singularity so by holding the throat open i actually mean preventing the singularity from existing and squishing you and along the way preventing the gravitational forces from first ripping you apart you got to do all those things you got to be not ripped apart and then not squeezed in to an infinitesimal point almost in the singularity so you need something with a negative gravitational effect like negative mass and that's invoking the tooth fairy right now because again maybe some day someone will figure out a way to either find this stuff or make this stuff so it's not completely out of the realm of possibility and i always like to be you know forward thinking you know not everything is possible but some things that have not yet been proven to be impossible might be possible although very very difficult you know that is intriguing so uh the singularity for people that don't know that um when we get into the math because i can give you a layperson's explanation of it's the point beyond which we can no longer predict what happens but what is the mass saying that it's infinitely dense yeah so what's called classical general relativity which doesn't include quantum effects so it can't be anywhere close to the final word okay nevertheless you know classical physics newtonian physics has served us well general relativity through gps has served us well blah blah blah the classical prediction is that no matter how much matter you throw into a black hole it all squeezes down to a mathematical point now a mathematical point has zero volume r the radius is zero so r cubed you know the volume is zero as well so that means an infinite density mass per unit volume um so no matter what you throw in you'd just squish to an infinite density again none of us really believe that because all other times when we've thought about nature on sufficiently small scales we've had to introduce quantum physics and so it is thought that the next big thing will be a quantum theory of gravity uh and you know hawking made steps in that direction he tried to unify quantum physics and general relativity but even if we don't get squished to an infinite density no doubt will be squished to a very very very very very high density unless we find some sort of anti-gravitating material that can preclude the formation of the singularity and the associated deleterious effects on our existence that's amazing okay so i'm going to keep asking ignorant questions because i feel like i'm sort of making progress in my layman's understanding here uh okay so we're worried about getting squished down way too small when i heard you describe that it it has infinite density as a lay person it sounds like i may have accidentally come to the same conclusion that that's sort of the only thing we can rule out we know it can't be infinite density is that what gives birth to this idea of on the other side of the black hole there has to be something spitting things out because otherwise it just seems like it it and again i just don't know anything about this but it doesn't seem like you could infinitely shove every quantum particle down into a something with zero radius right like something it seems like something has to happen yeah yeah yeah and you know by the way your your questions are perfectly reasonable and this is a very abstract you know mind-bending topic that a lot of people are interested in and so i get the same kinds of very good questions over and over again so they're great questions okay so the idea of it spitting out the other side or at least opening up into a black hole the other side doesn't come from the impossibility of infinite density yes we don't know how to get an infinite density but let's just suppose you could okay the mathematics still opens up to another black hole and it's just because can i stop you there so because i didn't understand the first time but i just let it go so if it's opening up to another black hole isn't that just something also sucking things in yes but from the perspective of something that went in on the other side it can come out so if it is that hawking radiation yeah well yeah um well that's related i'll get to that in a second if it goes into a black hole in our universe it can't come out of the same black hole in our universe but it can come out in a different universe it's called a white hole in that case okay do we have white holes in our universe no we've never seen one and this is why a number of us think that this is just a theoretical speculation and that there are no real such objects okay because you can't throw you know keep the throat of the wormhole open or whatever the white holes would be very obvious they would be things that are squirting out lots of matter they're very powerful they're very obvious they're not hard to find like a black hole that doesn't emit any light these things would be super obvious and yet we've never seen one so but but at least theoretically it's a possibility that even stems when you have the theory with an infinite density the infinite density is okay it's just that you have a mathematical solution to the equations that gives you another universe now often in physics we get solutions that you know have a positive and a negative sign so let me give you an example suppose i construct an experiment with a pendulum or something that gives me the mass of an object a paper weight and i tell you the the square of the mass tom is 100 square grams and then i ask you what is the mass what would be your answer if the square of the mass is a hundred square grams the mass is a hundred squared if it's not that i have no idea you have no idea how much math is a black box to me so so it's this you know 10 squared is 100 so the square root of 100 is 10 okay perfect so you'd say the mass is 10 grams if the square of the mass was 100 square grams okay but an equally good solution is negative 10 grams okay uh and by the way when you squared it that was an easy mistake to make because the way i phrased it i now see it was ambiguous what i meant i promise you it's not not your fault this is a yes but what i meant really was not to take the square of 100 but take the square root so that was an easy thing to make but the point is is that the square root of 100 is either negative 10 or positive 10 grams so we throw out the negative 10 gram solution as being unphysical right it's meaningless so the mass of your paper weight was 10 grams not a very good paper paperweight i should have taken a a different example okay a little ball bearing or something but we throw that out as being unphysical well you know who's to say someday someone won't find something with negative mass maybe they will maybe they won't so in the case of black holes a solution to the equations is this black hole or white hole in another universe but we don't know whether that's a physically meaningful solution that nature actually chooses to adopt or whether it's just a mathematically um possible but physically irrelevant solution like the negative 10 grams currently seems to be at least to me but again maybe someday someone will find what the negative 10 grams is you know and there have been examples of this in the history of physics a physicist named paul dirac about a century ago combined einstein's special theory of relativity where the speed of light is the maximum speed with the fundamental equation of quantum physics called the schrodinger equation he came up with something called the dirac equation the relativistic schrodinger equation and out popped a particle that looked pretty much like an electron which has a negative mass but it had a positive mass and at first he thought this was unphysical but then he said well why don't you know why don't you people look for it experimental physicists and they looked for it and sure enough there it was they found the neck the positive electron it's called a positron so um you know there have been cases in physics where the initially ridiculous looking solution or possible mathematical solution turned out to be something that corresponds to physical reality but there have also been cases where we've not found a physical counterpart the white hole being among the things we've never found another example is particles that travel faster than light in special relativity that's not impossible they're called tachyons they're traveling always faster than light and to slow down to the speed of light would take an infinite amount of energy well physicists have been looking for tachyons for decades and they've never found them maybe they don't exist or maybe we just haven't found them yet we we don't yet know see so we're exploring all these interesting mathematical solutions to see if they correspond to physical reality does that help you out very much so and so now i have a question tell me why this is wrong so as you're describing and obviously i'm existing in the abstraction layer of analogy but as you're describing this white hole and my my um you know whatever just the way my brain works the sort of leap it makes when i think about a black hole just sucking in all this stuff all this stuff all this stuff all the stuff and you tell me that the math says that there's sort of a black hole on the other side of that but it would really be this white hole it makes me the leap my brain makes is oh well on the other side is a white hole is essentially the big bang so you cram on one side all this stuff into a black hole cram cram cram cram cram and then it reaches some theoretical i have no idea what you know math it has to hit but it hits some point and now it has to eject and so what we think of as a white hole we we literally our entire universe is said white hole yeah that's a very profound thought actually uh there are fundamental ways in which the mathematics of a finite universe now by the way there might be infinite universes but the mathematics of a finite what we call closed universe like the 3d example of a balloon is very similar to the mathematics of a black hole nothing can ever escape from this finite volume this universe just like nothing can ever escape from a black hole okay it's just that it's an expanding universe it was born for reasons we don't yet understand as an explosion but in a similar way you can actually have a black hole within our universe that initially is expanding later on it'll go clunk and it'll collapse but you can create an initially expanding black hole no problem so in many ways the mathematics is similar our universe can be thought of as a black hole the fundamental distinction is that in our real universe a black hole is an object a structure where you've compressed the matter within this room for example and the black hole exists within the room that's different from the whole universe being the black hole do you see the distinction there it's kind of subtle a black hole in our universe versus the whole universe being a black hole there is a difference but mathematically there are a lot of similarities and there have been theoretical physicists who have been exploring that idea of our universe as being in a sense the ultimate black hole yeah oh man this stuff is so interesting and the i i struggle with one idea which is you can be anything you want to be but not everything and it really really bothers me that none of us will live long enough to see all of the answers um but when i start thinking about the the notion of einstein sort of in the later years of his life being trapped by his own ideology and really struggling with the consequences of some of his own theories um that gets really terrifying talk to me about how so even in this conversation i form a notion and then you'll say something and ah that notion crumbles apart and now i have to form a new notion how do we stay open-minded enough so that as you get more advanced in your career you have deeper wisdom you have more sort of threads to pull on but you're also more likely to have woven a false tapestry that traps you what do you do to be open to that new information yeah yeah it it's um this is a this is a disease that afflicts quite a few scientists theoretical physicists like einstein who become very set in their ways i mean einstein was a real revolutionary when he was young he was thinking of all these ideas that other people thought were crazy and his weakness later in life was that he became so wedded as you said to his tapestry that he wasn't willing to accept new ideas and the fundamental idea that he was not willing to accept was quantum physics ironically because of his many gigantic breakthroughs that's the one for which he actually won the nobel prize for an explanation of something called the photoelectric effect that's a quantum effect he explained it won the nobel prize for that not for special relativity not for general relativity and yet an inability to come to grips what with what quantum mechanics was trying to tell us about nature was his fundamental problem while he was trying to come up with a theory of everything it really didn't have quantum mechanics so we have to take those historical cases and keep them front and center in mind work hard at maintaining an open mind so you don't get fossilized so you don't get set in your ways and i would say that experimental physicists and observational astronomers such as myself i'm not a theorist though i like theory we don't fall victim to that as often as the theorists because we get better and better with time in some ways an experimental physicist learns more mistakes and how to avoid them so does an observational astronomer we build upon our past experiences and thus are able to do our jobs in many ways better with time but the true blue sky thinking theorist has to watch out for this affliction and consciously work at keeping an open mind yep let's talk about athletic greens the all-in-one daily drink to support better health and peak performance with so many stressors in life it's difficult to maintain effective nutritional habits and give our bodies the nutrients it needs to thrive busy schedules poor sleep exercise stress or simply not eating enough of the foods that your body needs that's where athletic greens can help their daily drink is like nutritional insurance for your body that's delivered straight to 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a distance um can you describe that for people absolutely yeah it's it's the essence of quantum mechanics uh and very very spooky in special relativity einstein showed quite conclusively and this has now been uh verified with thousands if not millions of experiments that no material particle with non-zero mass okay a photon a carrier of light has zero mass by the way it travels at the speed of light but no particle with non-zero mass can reach the speed of light let alone exceed it because it would take an infinite amount of energy to do so and as i said you know large hadron collider the stanford linear accelerator fermi lab near chicago all these accelerators have validated that concept over and over and over again takes a huge amount of energy to get particles going at close to the speed of light we can't get them to reach the speed of light the problem in quantum physics is that if you create a part two two particles out of one and let's say that that first particle wasn't spinning at all there's uh you know particles can spin sort of like tops in quantum physics it's a bit more complicated than that but think of it as spinning if the particle originally isn't spinning but then you create two particles one of which is spinning clockwise and the other one counterclockwise as seen from above let's say spin up and spin down quantum mechanics says that until a measurement is made you don't know which way the particle this one is spinning up or down clockwise or counterclockwise or this one and it's not just that we don't know the particle doesn't know and what that's really saying is that the particle is a quantum superposition of both spin up and spin down it's both states simultaneously until a measurement is made at which point it has to adopt one of the two states by a process that in quantum mechanics is still not well described it's not described for example by the schrodinger equation it's a bit of a mystery nevertheless once you make a measurement spin up let's say the other particle has to be spinned down instantaneously in order for them to cancel out and be spin zero that means the other particle learns as quickly as you want instantaneously that a measurement has been made on the first particle but that appears to be information or you know a substance a particle traveling faster than the speed of light i forgot to say this but a corollary of einstein's that no particle can travel faster than light is that more fundamentally no information can travel through space faster than light that's a very important part that i forgot to say but here it looks like information about the measurement of this particle reached this other particle essentially instantaneously that violates the fundamental result or consequence of special relativity einstein called it spooky action at a distance he never believed it it's called the einstein podolski rosen paradox because he wrote a paper with two of his postdocs or something and you might say well so far i've only described theory what about experiments do they validate this yes they do many experiments have been done where the particles are farther and farther and farther apart and you wait until they're really far apart you make a measurement of one of them and then essentially simultaneously just a short time later you make a measurement of the other one there's no way that traveling at the speed of light any signal could have gone from the first one to the second one telling it that a measurement had been made and yet the other one knew that a measurement had been made and knew which way it had to spin in order to be self-consistent that is so crazy it's totally crazy it's called quantum entanglement okay it is totally crazy sounding and you know as as dick feinman used to say you know relativity if you think about it enough it sort of becomes second nature even general relativity if you think about big masses enough and big speeds and all that it becomes second nature but if you ever feel comfortable with quantum physics it probably means you haven't thought about it sufficiently deeply and he's the person of all the people i've ever met who had the deepest most intuitive view of nature of anyone that i met and he basically said if you think you understand quantum mechanics you haven't thought about it enough okay yeah richard feynman is a a very interesting character so as somebody that knew him what what was it in in the things that he said or or things that he discovered that made you and so many others say that this guy really had just an unusual intuitive understanding yeah it you know it's just that he he had this way of looking at things he he had a way of of thinking about what nature is actually doing and only later would he work out the mathematics but the idea came first and one of the best known examples of this are these things called feynman diagrams where he'd write down these little squiggles little pictures showing the interactions of particles and then he made up equations that you have to apply every time you know a particle splits into two or whatever but it almost looked like chicken scratches that were pretty arbitrary to his colleagues initially but it was his way of thinking about the world and then he developed it mathematically and he could do on a chalkboard in half an hour a problem that using the tried and true brute force method might take 50 or 100 pages of very complex calculations it would give the same answer you know but in a much simpler way so again this goes back to what we were talking about where it turns out these are equivalent theories but his way of looking at it was so different and so fresh that it looked like a completely different model even though if you delve into it and this is something that freeman dyson did he showed that the different theories of or the different formulations of what's called quantum electrodynamics which discusses the electromagnetic interactions between protons and electrons in an atom things like that the three major theories that existed were basically equivalent but looked very different and feynman's was by far the most intuitive so it was this intuition about the world that struck me uh as being quite astonishing and you know i i knew him now close well basically 40 years ago now when i was a graduate student at caltech and in those 40 years since then i've never met anyone who had that kind of advanced and very intuitive mental notion of how nature works yeah there's something about him that certainly lasted and from what i've heard in very iconoclastic sort of uh bombastic personality uh yeah sound like a pretty interesting guy he was an interesting guy he he had a very interesting personality i mean i i think one of the things that sort of irritated some of his caltech fellow faculty is that um you know he claimed not to like attention and stuff but then he wrote all these books about his life and he he kind of went out of his way to tell stories about himself with or without embellishment i don't know i wasn't there to experience them firsthand but they certainly seem quite amazing stories and so if you don't want attention why would you go around telling these stories about yourself but you know i liked him a lot and i liked his stories and the other thing that rubbed off on me from him was that he felt very strongly that if you can't explain something in a reasonably simple way to someone who does not have advanced knowledge of science and especially physics then you probably don't understand it very well yourself and that's one of the reasons i enjoy teaching the introductory astronomy class at cal i enjoy being in lots of science documentaries i give a lot of public talks i do these interviews and stuff because it gives me a chance to explain science to the general public and often in the middle of the explanation even some of the ones i've given you tom i'll be totally honest in my mind i'm thinking once this is all done i've got to go back and think about this some more because though i said the words i'm not sure i really understand what those words mean okay i'll be perfectly i i get that and i think that's really powerful that you do that it's you know i'm sure a huge part of the reason that you're as good as you are is you don't just go ah i got away with it you know it's like you want to go and keep keep learning i love that keep keep learning keep uh striving for a better understanding of the world i mean you mentioned that you'll never know death and blah blah blah one of the things that most bothers me about death is that i'll never know what what ideas are raised and shown to be correct in the future i'll never know what what ultimately becomes of human society of of the planet earth and and so on and i know that's the way it is but it bothers me yeah it bothers me because in my finite time i want to learn as much as i can and so i i run a lot i i jog a lot i know you're really into fitness and stuff and so you know books on tape podcasts you know lex friedman's thing been listening to a lot of those your things books on tape audible it's fantastic i don't have that much time to sit and read i do sometimes but i have a lot more time an hour a day to run and walk and take hikes and i listen to things at the time so i'm continually learning i am obsessed with that idea uh it's what i call transitional moments so it could be the gym it could be brushing my teeth walking from one place to another cooking a meal i am always listening to a podcast or uh youtube video in fact oh my god anybody if you if you have made it this far let me tell you right now you've got to check out alex's great courses which are phenomenal uh amazing man the fact that people like you have taken the time to create these extraordinary classes and make them available uh i feel like the age that we're living through where youtube is available like i know you will remember this i remember this having to go to the local universities library to do homework because there was no internet your family didn't have enough books to like even begin to scratch the surface and the fact that now you can put the most random search into youtube and somebody's got a video for you and usually there's dozens or hundreds of videos it's really extraordinary it's an amazing educational opportunity and as you say there's a lot of free stuff online you know the great courses go on sale every once in a while quite frequently where they're just like a buck a lecture or something like that it's it's ridiculous i don't know how they make any money but whatever that's their that's their thing you know clearly they're very successful at it but i did those courses as a way to further educate the public not just uc berkeley undergraduates and those courses were done quite a number of them you know before all these youtube free videos of various public lectures became available uh so those are a great compliment but for a course you know from step one to end you get the full set of lectures that essentially i give here at berkeley that's that's amazing you know they're extraordinary yeah yeah so something i want to learn more about i want to go back to quantum entanglement yeah so if you had to guess or there must be theories what's your favorite what what do people think is happening how is information traveling faster than the speed of light yeah you know honestly we don't know but there are a number of ideas um one of the most crazy sounding and i'm still trying to come to grips with it is this thing that goes back nearly half a century it's called the everett or everton wheel or many worlds interpretation of quantum mechanics this is different from the cosmological multiverse where we were talking about you know little bubbles in some bigger hyperspace or a universe that's becoming so big that there are different little volumes within it that we can't communicate with but nevertheless exist those are all astronomical or cosmological multiverses but there's a thing called the the quantum multiverse and the idea is is that although these particles were a quantum superposition of spin up and spin down and any particular measurement forced it to decide so to speak in anthropocentric terms you know up or down there's some other universe where it was the opposite and so in the many worlds interpretation any time you have a quantum superposition and then a measurement is made there exists then at least mathematically in what's called hilbert space which is a mathematical space of all possible universes those other possibilities exist and i just said those words and this is an example of me saying the words to you but not truly understanding what the hell i'm talking about because i ask you know sean carroll and other people will you know sean is a big believer in this he has a good podcast as well by the way um and i say well where the hell are these things and he said well they're they're in this mathematical hilbert space and that just leaves me a little bit cold i'm the guy who knows which end of the telescope to look through you know i'm a hands-on person and i want to know where the hell all these universes are okay um so i'm trying to learn more about that and and uh come to better grips with it but that's one idea okay and more and more quantum physicists are coming around to that that there exists in some weird mathematical way all these other universes but another way of thinking about it is that you know once you made the measurement of one particle you don't know that the other particle was spinning in the opposite direction until you come and talk to the experimental physicist who measured that other particle or you come and take a look at it yourself or something like that direct communication but that had to be done at speeds less than or equal to the speed of light so how do you know that the decision the the measurement in a sense isn't made when they come together to compare results now the other guy can tell you well i i made the measurement an hour ago long before you came to visit me and that's the way it was but in some weird quantum mechanical entangled way you know something isn't reality until a measurement is made that two observers at the same place and the same time can agree upon okay so people can say stuff but but the measurement from the other person's perspective hasn't been made until they come together and compare results so some people have been thinking about it that way that we might just be confused that it's not actually traveling yeah yeah and then others i mean i think feynman would have said we are stuck in our classical way of thinking and even relativity is a classical theory it's not a quantum theory and there are many things in quantum theory that in fact violate your classical sensibility right it's just not the way the world works mr einstein there is spooky action at a distance i mean you can call it that you can call it spooky but that's just the way the universe is it's probabilistic and it's not even that a set of particles exists in which each of them is a particular way and you just don't happen to know which way it is no they are all a quantum superposition until a measurement is made and you know you might think that in the end this is all just again theoretical mumbo-jumbo and intellectual titillation and why should we pay people to think about this stuff well you know there's now this new area about which i know very little just a little bit you know quantum computing where instead of bits ones and zeros you have qubits and you might have a three digit number you know one zero one where instead of knowing what each of the digits was a one or a zero or a one you know some quantum probability distribution that sounds like a lot less information and it is but it turns out that for certain types of calculations you don't need to know the value of each of those bits it's good enough to know the probability distribution this quantum superposition and you can do some types of calculations more quickly so right now people are only just barely working on these quantum i mean they're working hard i said it wrong but you know it's hard to keep these things cold and isolated from the environment because as soon as you have some photon that interacts with it you have what's called quantum decoherence and you no longer have this superposition so there are big technical challenges but one of the great things about homo sapiens is that we embrace technical challenges we go for it we climb the mountain because it's there first because it's interesting but secondly because it ends up having unanticipated spin-offs and these quantum computers in 50 years may be the the main way of computing at least certain types of problems right so you never know what the practical spin-offs will be of these wild-eyed crazy-haired theories that uh that you know people that are incredibly creative um and intelligent think of you know i think there's even even more to it than that one thing that so when i originally started making youtube videos it was like all right look i know what my brand is going to be it's all around empowerment i want to help people manage sort of their mental state because that had changed my life so extraordinarily when i got a grip on my own mind and saw that i was able to take myself so much farther and then i was like i for my own sanity i have to start branching out beyond that and in trying to explain to my team why i felt it was so important it was you you get empowered so that you can do something and you don't just get empowered to sit around empowered it's like just like skills have utility you want to go put that utility to use and getting people to you i study weird things that i never know how they're going to come to use in my life but they'll come to me as an analogy that makes something else make sense they'll allow me to connect dots that i otherwise wouldn't have been able to connect and so you know you're unless you're you just want to be a follower you absolutely must encounter novel ideas outside of your your realm of influence and part of the reason that i think i've been as successful as i have been is that every 10 years almost by accident i've had to completely reinvent myself and so i started out in film then i went to technology then i went to nutrition and now i'm back in media but media in a way that has changed in the intervening 20 years so radically as to be almost unrecognizable from where i started and i heard this quote it literally to this day haunts me and is why i asked you that earlier question about staying sort of mentally supple is genius is a young man's game and i was just like oh god as somebody who's a late bloomer i do not like that idea whatsoever the fact that most people get the nobel prize in their 60s for work they did in their 20s like i'm just i'm not okay with that and when you look and i forget who said this you might know there was a guy i think he's won two nobel prizes could be wrong about that but he said it was because he had uh i think chemistry and maybe physics and he was like it's the area of overlap that i have these two gigantic worlds and where they collide i'm able to make novel insights that i wouldn't otherwise be able to make and so that became sort of this rallying cry in my life of to have novel insights i've just got to take in data that i can't yet predict how it's going to be useful i follow my interest it's not just sort of blindly taking in data but in doing that i find whoa like things collide that i couldn't have predicted and your background in chemistry feels unaccidental to me that you would be as good at what you do as you are does that make sense to you yeah you know i have this background in chemistry from age 10 through 17 it was sort of all i did and at the age of 14 i got a small telescope as a gift and the third star i looked at turned out to be saturn you know so that was a great thrill no one you know told me to look at that that would be saturn i discovered it on my own that night didn't matter that millions of people already knew about it so that started me off on astronomy on a steeper slope but i always still liked chemistry and this whole exploration aspect of science as a whole and now i you know i still study explosions explosions of stars i mean i used to study explosions of chemical compounds and stuff but they're all interrelated they have things that you can apply from one subject area to another and they're useful if you keep your mind open so i think my studies of chemistry and being interested in science in general were definitely helpful but getting to another thing that you said there you have this open mind you've got these new ideas you're setting a new course for yourself as you did with you know quest nutrition for example but it was hard work you had to put your butt down and work damn hard to get there to grapple with new ways of doing things and stuff and as physicists as scientists initially we come across these new ideas quantum entanglement and all that and you have to just struggle with them and work hard on them and approach them from different perspectives it's not going to be easy but you know good things are hard to do and hard things are good to do right you know ultimately the satisfaction you get will be in some proportion maybe even to some power of the effort and devotion you put into something it's not going to come easily and you know just last week there was uh this hubble space telescope deadline every year you apply for time and you know i had a bunch of proposals that i was on and a few that i was leading and here it is it's thursday night they're due on friday and you know i put in an all-nighter or nearly an all-nighter and then i slept a lot the next day um it's okay once in a while to do what is needed to be done to continue on and i'm not saying get perpetually too little sleep but i think it's been shown that if you skip a night once in a while and just get a lot of sleep the next night that's okay if you skip a week or two weeks then you can't make up for it but my point is simply that sometimes it's going to be hard but that's part of the reward it's the sweat it's the grit that you put into it and you've done that right you reinvent yourself every 10 years i'll bet it doesn't come naturally if it does more power to you but i'm guessing that you have to put in the sweat sweat blood and tears to do that and scientists need to do that too in in all walks of life to be a leader you got to do what it takes sometimes i agree and this gets in so i love your disclaimers about sleep and i'm the same you want to do things to make sure that you're around as long as possible but i'd be lying if i said that i didn't find i forget who the mathematician was but there was this mathematician and just for the record i don't do drugs but there was a mathematician who was notorious for doing speed and um one of his friends came to him and said look man this is ridiculous you're you're gonna end up killing yourself you need to stop doing speed and you're an addict he said i'm not an addict i could stop any time the guy's like all right fine do it stop for a month and so he stops for a month and at the end of the month he the friend says you know don't you feel better and you know i am impressed that you were able to stop and he was like yeah i told you i could stop but we've just set mathematics back 10 years and that idea of being so obsessed with something that you really give yourself to it because i am i am well aware as i eat very cleanly i prioritize sleep i my relationship with my wife is my number one priority loving relationships all of that like so so so important but at the same time i'm shortening my life because of how fast and hard i go all the time but i love it and i make no apologies for it and it is i forget the exact quote but it's like what i want to do with my life is help people find the thing that makes them come alive because what the world needs is more people who've come alive and that like wanting other people to come alive in the way that you've come alive with astronomy and the way that it pushes you to you know pull an all-nighter or to um stay up all night watching to make sure the lick of observatory didn't burn down during the fires i mean there's just like i don't know man to me that's like the beauty of it all it's that same sense of poetry that i get when i look into the cosmos and just am horrified that i won't live long enough to see all the answers and thrilled that i live in an age where we look up to the stars and have some context of what we're seeing yeah absolutely you know jumping off from what you said it's yes we all want to live a long time and that's certainly my my uh one of my goals but uh it's the quality of the time that you live that's actually more important than the duration you know if from age 70 to 100 you're you're essentially a vegetable okay all right you're alive that's fine but what quality of living are you getting from that you know so i'd rather live vigorously and get more out of the time when i'm conscious and my heart is beating and i'm doing things and enjoying nature and making discoveries learning about other people's discoveries i don't want to stagnate during those waking hours you know even if it means that i'll have fewer waking hours but if you eat well exercise and rest and this is part of the message you give in so many of your presentations you're likely also to to live a long time right so they don't have the energy to push they're not mutually exclusive here now you know when i was young i was kind of a maniac i really did get way too little sleep i now acknowledge that it was probably bad for me in the long run fortunately right now i'm still very very healthy and um don't seem to have suffered any clear side effects from my maniacal youth but i i was crazy uh as a as a student and a postdoc and or you know assistant professor i mean i just i worked all the time and it's in part because i loved it i mean it was mostly because i loved it sure i wanted to get a job and all that but i wasn't really worried about that because you know if i work hard and produce good results the job will come with it but it was because i loved it so much and still do love it that i have to stop myself some evenings and say look alex it's time to get some sleep you know you can start again the next day but often my mind is racing with the things that i've read or thought about and it can be hard to fall asleep that's my problem actually when i get enough sleep it's hard for me to fall asleep at an early enough time to then not have to for example turn on or set an alarm clock and i know that you don't like to set alarm clocks and i confess that i can't exist that way because i i would end up you know falling asleep too late and then sleeping through my morning appointments or my classes or whatever yeah no i definitely get that so let me ask you if you could either look into the future a number of years to your uh discretion or into the past to whatever period you want to look to which would you choose oh gosh i would look toward the future you know and i'll just first first the future because we do have ways of examining the past that's one of the great things about science you know geologists study the strata in the grand canyon astronomers look at progressively more distant galaxies and thus they're looking back in time a time machine by the way this is one of the things that i try to teach my introductory class besides we are made of star stuff by looking farther back in distance we we're looking further back in time so there are many ways of recreating what happened and learning not the details but you know archaeologists they look at they look at ancient societies and stuff so we already know a fair amount about the past and that's thrilling but i really want to know about the future what in particular is going to happen to humanity are we going to be stuck on this planet and is something going to go drastically wrong because an unanticipated asteroid hits us or we're neglectful of earth um or don't you know and don't recognize what we're doing to it or there's some megalomaniac who just says well i'm going down so everyone's going down with me you know whatever some human-induced disaster or some extraterrestrial disaster that whites out life on earth is that what's going to happen will we be elsewhere before that happens spreading our seed elsewhere etc i want to know what happens to us to humans not just to the universe i think the universe will expand forever but uh you know and eventually stars will die out but i'm deeply interested in plants and animals and in particular humans on earth what's gonna happen to us and is that a hundred years in the future a millennium i hope not such short time scales though they might be i'm hoping it's millions of years if not tens or hundreds of millions of years so if you got granted access to one moment in the future but you had to pick a specific number of years in the future how many number of years would you pick yeah that's an interesting question um you know a million years is a little bit silly because it would be almost like probably things would be completely unrecognizable or maybe we wouldn't even be here maybe we'd be completely replaced by robots i don't know uh 10 years is way too little even 100 is a bit too little so in round order of magnitude you know factors of 10 i would say a thousand years would be really interesting in 3000 bce uh sorry ce i was putting myself 5000 years ago but in 3000 ce what will life be like and what will humans be like here on earth and will we have progressed elsewhere i mean i'm a i'm a big fan of space travel and exploration in part because we're pioneers explorers by nature in part because to improve our chances of survival we really do need to put us elsewhere and in part because it's such a giant technological challenge and i like challenges and humans are good at at you know addressing and meeting challenges and space exploration i think is inspiring to the kids as well so it helps them motivate them to go into stem fields you know science technology engineering mathematics and most of them won't become rocket scientists but that's okay they'll go on into fields that are more immediately useful to society medical physics applied physics engineering computer science all all these things are good reasons to do space exploration so how far will we have gotten in a thousand years you know how far do you think so barring the sort of cataclysmic human error of some kind uh how far do you think we get in a thousand years i think in a hundred years we'll be on mars um maybe not a gigantic colony i know elon musk is i think in january 2020 he said a million people by 2050. i don't think that's going to happen he said one person by 2026 whoa said this only a year and a bit ago and he said an uncrewed spacecraft by 2024 you know i don't think those things are going to happen but it's great to be ambitious like elon is right he motivates people he gets them inspired so what if you don't meet your timeline at least it gets people pumped up so his timeline is gradually being revised we'll see what he says when we get close to 20s 26 and there isn't a person on mars yet but sometime in the 2030s there might be a person on mars by 2100 we might have a small colony in a dome i think it's very difficult to terraform mars not completely impossible but there are big issues but we might you know build domes or something so the point is have at least some of us somewhere else so that in case something happens on earth bad we are elsewhere and i'm not saying i'm not using this as an excuse some people are sometimes critical of this line of reasoning that oh you're using this as an excuse not to take good care of earth no i want to take good care of earth the best that we possibly can but we hedge our bets right by placing some eggs in a different basket folks things could go wrong no matter how well we think we're looking after earth um you know so it just makes sense to put us elsewhere and of course we want to respect any indigenous life that is elsewhere but i think the odds of mars having anything beyond bacteria are remote and even the bacteria are not a high probability in my opinion so i think that will be you know land that we're not taking from anyone or anything so why not basically spread homo sapiens yeah i'm i am aggressively on board with that and i think that you know one thing people maybe aren't thinking through is that when people started going west it's not like the cities crumbled and nobody cared about them the vast majority of humanity is going to stay here and even if all the people that left didn't care which of course i think they would i think they would care maybe more like there's something about it still being the homeland the people that you love that you're leaving behind you'd never want anything to happen to it but that no matter how good beautiful a city gets people have always ventured into the unknown and like you said it's so inspiring to people um so i am wildly motivated by space travel even though i agree that you know it's like protect earth first that's you know the only logical sort of self preserving way to think about it but there's something about feeling like you can go beyond and i mean i'll use a word that people are going to hate but you you go and you conquer like you you put yourself at tremendous risk i mean think about the polynesians as they set out onto the ocean like that's so crazy when you see the boats that they got in and found a way to find these like crazy tiny islands and the sort of awe that i think about those journeys i think about a space journey it's so exciting to me oh yeah and you know how many failed polynesian expeditions were there where they didn't come across hawaii or one of the south sea islands or whatever yeah but they were explorers right and i i feel the same way it's going to be hard though and there's going to be some failures but we are i'll be your explorers you know do you think we'll have the stomach for that when the first uh people on mars end up dying on mars will we have the stomach to send more people oh i think so um you know the government has to be very very careful because if someone dies it's a big pr disaster and all that in the private enterprise it's not that way you get people who want to go who understand the risks um there isn't the government responsibility and that you're using taxpayer dollars and oh you know suddenly a teacher died like in the challenger disaster that was that was horrible i mean it was a you know it was just a tremendous loss um you know i understand they had reasons for wanting her to go but but you know she wasn't a trained astronaut who had agreed that these are the risks that that profession is gonna entail you know i'm sure she understood that uh it was a dangerous mission but there hadn't been a failure up to then so we were pretty good and so maybe we even became a little bit complacent right about what our success rate will be but that was a dangerous thing right and it was a publicly funded thing it was nasa but in the private domain i think it's a different story first you can do things cheaper and faster secondly you can recruit people who at least initially let's say they plan on dying there maybe they have even a terminal disease they don't even plan on coming back but the thrill of being among the first people on mars you know if i didn't have my family to to think about and i do you know i sometimes have asked this hypothetical question if i had a terminal disease and if i had very little to live a year just enough time to get to mars would i go there you know just just just for the thrill of the experience and i know that my family wouldn't like it and so i probably wouldn't wouldn't do it but you know just between you and me and all the people who are going to listen to this yeah it's a it's something i've thought about not that it's a possibility right now and not that i hope i get a terminal disease but initially it's going to be people who are who know that they're not going to come back because bringing someone back is even more difficult than just landing them there uh and landing them there is a lot more difficult than just landing robots there because you don't need to deal with oxygen and waste and water and food and if some robots you know get destroyed in an explosion or a failed landing well all right so what at least it's not human lives but as long as people understand the risks that are that are that they're taking yeah i think there will be such people and indeed i think there's there's some mars one company or something like that that already has a list of people that they have who are saying yeah we'll go on a one-way journey and we understand the risks do you know ernest shackleton and the endurance yeah have you ever read the ad that he put in the paper to get his crew i have i either have not read the ad or i don't remember it please remember oh my god it is so good i uh i had to look it up the other day and read it to my wife because i'm like you want to hear the kind of people i want to be around it i don't have it memorized but it goes something like this looking for men who are interested in a job that will entail entail bitter cold low wages extremely difficult to reign almost certain failure unlikely to make it home alive but glory and something else if we're successful and that was it and he crewed up man people were ready they they were they wanted that challenge they wanted the shot at glory and you can say that people are foolish for wanting it man but there's something in the human spirit that there is a sub set of people who were just like sign me up and uh ah man i i find that really inspiring yeah well you know so so mars i think is a very real possibility and there will be people who who want to go and a colony might get set up in some sort of a dome with air in it there's already practice being done there's some place in arizona where they basically isolate themselves for a year or two inside a dome biosphere i think it's called yeah practice living under such conditions um you know elsewhere in our solar system becomes more difficult although not impossible but ultimately given that even our sun is gradually growing more powerful and you know that's not the cause of the current climate change but ultimately it will in a billion or two billion years the oceans will have evaporated away um that could be compensated by a lowering of the carbon dioxide level by a substantial amount but that then makes plants angry okay if you lower the carbon dioxide level too much so within about one or two billion years conditions will be fairly unlivable here on earth now that's a pretty long time scale nevertheless if humans or their evolutionary descendants live that long we have no choice but to either either move our planet farther away or go to mars or whatever but even those are temporary solutions we've got to go to other planetary systems and there i think it's much much harder because you know the nearest star it takes light four and a quarter years to travel it's 4.2 light years away that's 25 million million miles okay it's it's an unfathomable number right it's that's the close one yeah it's the closest one right in my you know to give you an example of one of the analogies i use in my class suppose our sun which is 109 earths across so the sun is big okay squish the sun down to a grain of sand and then scale all other distances by about by the same factor okay so on a scale where stars or grains of sand the nearest star is about 10 miles away okay yeah stars are grains of sand and they're spaced 10 miles apart from one another or 10 kilometers it doesn't really matter we're just order of magnitude here so these are gigantic distances and so though i'd like humans homo sapiens to get to planets that we know are orbiting other stars and astronomers are even finding ones that more or less live in the region where water might exist on the surface in liquid form and all that the so-called goldilocks planets let's say we find one and we want to go there it's not going to happen with humans because of the length of time it takes to get there or the inordinate amount of energy to get spacecraft up to a very fast speed it could be done with frozen embryos or something with some future technology maybe but even there the embryos are frozen but there are still all these charged particles called cosmic rays that will interact with them cause cells to you know dna to mutate and stuff and usually mutations don't have good consequences so a better way than with flesh and blood is to send robots that could then you know fix themselves if some charged particle messes up part of the circuitry and then using the raw materials on the planet they could build copies so our evolutionary descendants could well be robots and if that is very distasteful to you i could also imagine where the robots are there on another planet you sent them there but then you send human genetic code as a bunch of ones and zeros using a radio signal which travels at the speed of light and the robots get that genetic code and then they could create humans that would be a way of getting blessed yeah without actually physically sending the flesh and blood yeah it's really interesting so whoa whoa whoa yeah uh i could send a robot there and then send my own genetic information like me personally this would basically be a clone of me yeah yeah so you assume the robots are already there it took a long time to get them there okay some future generation the robots are there and now you say i tom want a clone of myself on this other planet orbiting a star you know four light years away you encode your whole genetic code but you know as a bunch of ones and zeros right and you send that information as a radio signal radio waves travel at the speed of light four and a quarter years later that signal with your genetic code reaches that planet the pro the robots have been programmed to receive so-called right like but the eagles thing we are programmed to receive right but they are programmed to receive and they then build a copy of you i mean that that's not possible right now sure but i don't see anything uh that violates any known laws of physics that's always my standard does it violate any known laws of physics if it doesn't let's consider it if it does well maybe there's a way to circumvent that but that's a lot more speculative but this is not that crazy you know i like that idea a lot so i'm writing a story right now about um it's called coyotes of the air gap and it's all about basically a future in which people's consciousness are uploaded into these great clusters of servers kind of like the matrix but imagine if you were aware like when you died you you know upload your consciousness and your consciousness carries on you have all your memories but you know that you're a digital entity and if we actually get to the point and i know that we're a long way away from it but if we actually got to the point where we could upload our consciousness then that means that i could send my consciousness somewhere have it sort of essentially redownloaded into either a purely robotic body or a sort of combination genetics robot or genetics entirely um created by the the robots man that's so interesting to me as somebody that so i don't have kids so there's no um i don't know if catharsis is the right word but there's no like that that sense of sort of denial of death and that i have children that will carry on my legacy so i think a lot about how do i get my consciousness at least uh you know to live on so that that's really interesting it makes me want to write a story around that no it's totally fascinating tom and if you're not hell-bent on having you know a physical copy of yourself if that's not so important if what's going on your in your mind is the most important thing then indeed uh essentially storing the contents of the brain as a bunch of ones and zeros it's a it's a lot of them okay and all that we don't even really know what consciousness is but you'd want to reproduce everything right you'd want to reproduce not just sentience but consciousness and empathy and and feelings of of love and desire and pain and all that not just a nervous nerve pain but you know an emotional pain if you want all those things it's going to be a lot of bits nevertheless if what we are is a bunch of ones and zeros and i don't know that we know the answer that question yet but i actually you know i think that's what we are we're a very interesting set of ones and zeros nevertheless it's a ones and zeros then yeah a way to immortality might be to store the contents of your brain every five minutes or every hour or whatever somewhere else and even beam it to another planet even but you know it could be in some cloud storage so to speak right and then if you get run over by a truck it gets downloaded to either a new person but not a person probably a you know a computer a robot but again if it's your if it's your mind that you find most important and you don't really need your body then you're just some you know you're just a robot there you're just a computer but you're having many of the same thoughts okay uh not all of them because of course you you don't have the same physical interaction as when you have you know hug someone or or make love or whatever right but at least the thinking part of you where you're thinking your abstract thoughts and trying to explore the world and thinking about quantum entanglement all that could continue and your memories of what you did as a kid and what you did in your career they're all stored in that computer and so so in that sense you've bought yourself immortality right i mean i i find it depressing when i forget things because a big part of me is my memories and when i forget things it's like part of me is lost and i guess i'm not aware of it unless someone brings up the subject whose memory i've forgotten but sometimes i get together with my old grad school buddies and they'll bring up something i'm all oh man i had totally forgotten that we did this or that 40 years ago you know and here you'd have them all at your disposal maybe it would be an information memory overload i don't know you know maybe it would be a bad thing it's interesting to think about what what makes us human what would humans need to put into the robots in order to feel that whatever we value about the human race has lived on because even as you're describing it's like yeah man they're part of what makes us us is the pruning it is the fact that our memories are malleable right and we wouldn't recognize a human experience the way that a robot or a hard drive is is literal like these are the ones and zeros that you've laid down they will be those ones and zeros every time you access them and part of what makes humans so interesting is the malleability of our memory is the way i just had a sleep doctor on of all people who was talking about how one of the fundamental reasons that we sleep is that we're taking that experience from the day and we're sort of wiping off all the hard emotional resonance and then putting the memory back as sort of knowledge without the pain and so we said a better way to think of it is time doesn't heal all wounds sleep heals all wounds yeah to the the notion of well if you have a hypothesis that should make predictions one of the predictions is that there should be in people that have ptsd where sleeping doesn't seem to reduce the emotional stress you should be able to measure that in their blood and you can and it's the amount of noradrenaline should go down at night for people with ptsd it doesn't and so it stays elevated and so they found that if you give them there's this heart medication drug that has this bizarre side effect of it lowers the noradrenaline in your brain if you give them that their ptsd goes away it's really really interesting just i bring that up in the context of where's that line for humans you know what i mean does it have to be meat like you need to ship meat my my meat suit to another planet is it just my mind but so much um lisa feldman barrett wrote a book called how memories are made or how emotions are made and she talks about how without your body you you literally wouldn't be able to make sense of your world and because there's this two-way communication between the body and the mind anyway so interesting to me yeah you know on this topic a bit of a tangent but not completely you know you you emphasize sleep and memories and emotions and all that another thing i find that really makes my life full and that accentuates memory memories and the process of living and all that is to occasionally go through mind-blowing experiences and i have here a shirt that my wife wife helped design it's of a total solar eclipse it was august 21st 2017. we were in oregon but if you've never seen a totally eclipsed sun where the moon blocks all of it all of the bright disk it is a mind-altering highly moving emotional experience that you will never forget and that can keep you going sometimes in in low times or whatever i don't know tom have you ever seen one of these phenomena a total i saw a partial eclipse and that was awesome well so that's awesome but you haven't lived tom despite your very full life april 8 2024 the path of a total solar eclipse goes right across the u.s goes through mexico enters texas goes up to the northeast new york and into north into eastern canada april 8 2024 put it on your calendar be on the path of totality you might be at 90 95 98 eclipse but it's not the same it's more than a night and day experience tom you got to be within the path you know call me or write to me after you've experienced it you will be a transformed person and you will look back to that date and time and that experience throughout the remainder of your life as one of these things that you're glad you put on your bucket list and did experience and it didn't cost very much to do so i mean the path goes right through dallas texas and a bunch of other cities usually these things are in the distant corners of the world and it's a great way to travel by the way if you have the time and means to do so as my wife and i have been doing i've done 17 of these things but this one is going to be really easy for americans to see april 8 2024 tom don't miss it you'll thank me have you ever had to put words to why it's so moving it's difficult to put words because it's such an out of body out of mind experience your jaw just drops when the last bit of the sun gets covered you get this thing called the diamond ring effect right at the beginning of totality and right at the end that's a magical moment then you look at the total eclipse and you see this corona surrounding what looks like a black hole in the sky and it's just hanging there and you're all like oh it's your mind turns to mush many people who try to photograph it you know if unless they have their sequence practiced many times they'll flop up better to have a computer running it because you don't want to be messing around and distracted by that plus the photographs and even the videos don't show the whole experience it's the the temperature changing the light changing very quickly the corona coming out the people reactions it's a very social experience for some others want to experience privately whatever your thing is the whole thing is just marvelous and quite indescribable in work i mean i now i know i sound like a nut you can call me a lunatic that's a bit of a joke right nice once you've seen one you will see why those of us who have been there talk in such nonsensical terms about experiencing a total solar eclipse so i'll definitely check it out april 18 24. do you think that there are other beings in the universe that have a similar um take like is there any human-like alien out in the world out in the universe i should say no maybe maybe um the universe is a big place and uh within our observable universe there's something like ten sorry like something like a hundred billion galaxies um even more if you count the little ones each galaxy has billions of stars ours has more than 100 billion stars so when you you know multiply all the numbers together there are a lot of stars there are a lot of planets a lot of them are potentially habitable the thing is though that we don't know how life came about and we don't know how it evolved to intelligence at our level and at least on earth it was a very unlikely process throughout most of the history of earth in fact it didn't happen you know homo sapiens were around starting 250 000 years ago early hominids four million years ago out of the near 4 billion year history of life on earth there hasn't been anything like us and moreover intelligence and mechanical ability at our level is not a clear evolutionary advantage so for those reasons and some others i think that life as advanced as ours is out there but not very common and that might be a minority view but i think i have good reasons for thinking that um you can't just say there are a lot of stars out there and surely they're teeming with life there are a lot of factors that lead to life and then intelligence and mechanical ability at our level and i think they're fairly rare i don't think we're unique but i think they're pretty rare at least in our galaxy you know yeah i mean the fermi paradox certainly introduces the idea of well if they are there where are they like why are they so quiet right if if they're really common then we should have seen them in abundance the fermi paradox does not explain things if they're if they exist but are not very common then then you can explain the very paradox so i'm not using it to argue completely against the existence of other things and plus again i think a natural evolutionary process does given enough time and circumstance lead to things like us i just don't think it's a very common process you know yeah one one of my favorite statements about the universe is uh and i unfortunately don't know who said it but um if you bombard a planet with photons long enough it will emit a tesla and uh i thought that was hilarious uh since that is precisely what happened here on earth um well the monkey's typing uh on typewriters and coming out with romeo and juliet right so true yeah it's uh when you were when you were describing the solar eclipse it just that notion of the the wonderment of what the universe has created in in us you know that we are star stuff thinking about the very nature of stars and and and being awed by it isn't that magical yeah very right and to be awed by an eclipse and by the way other planets in our own solar system don't have moons that have the right size and distance from the planet to give you as nice and an eclipse as what we have so you know we're privileged to have it we are able with our minds to enjoy it and appreciate it you know whales and dolphins are pretty intelligent but i don't know that any experiments ever have ever been done to see whether they appreciate the ah and the beauty of something like an eclipse or even of their own existence right do they tangibly understand that they exist and the intricacies of evolution that led to their being we do and that's part of what makes homo sapiens so special right and i'm not denigrating whales and dolphins in any way i'm just saying that as far as we can tell our minds and the way they work and the emotions we have not to say that a dog can't experience sadness it can okay but again we are at a level that's really quite extraordinary even considering the tens of billions of other species that have lived on earth you know there's nothing quite like humans other than the apes but we are descended from the apes and you know we're just farther along that sequence and it's it's magical and marvelous and each of us should do what we can to get the most out of this life that we've been given you know in our own way all right well for people that want to take you up on that and get the most out of their life where can they connect with you yeah so my wife is just starting up a website called astronomy.club i will have um you know things like celestial sites that are coming up eclipses things like that you can ask me a question every once in a while um i'll post links to various public talks and things that i've given so we're just starting up we hope to have it running soon we will by the time this um this uh interview appears so you can you can reach me there and then of course if you just google my name or whatever your favorite search engine is there are a lot of public talks that that are on the internet and then of course there are the great courses it's a company that that sells these courses i did a big introductory course with them i'm hoping to do a what's new in astronomy course sometime in the next few years with them um and then i have an introductory astronomy textbook through cambridge university press the cosmos so i think we'll have links to all those things on the astronomy.club website and um so i hope to see some of your followers there uh tom and thank you for the privilege and honor of talking with you man thank you so much i really really enjoyed my time this was a lot of fun and guys speaking of things that are a lot of fun if you haven't already be sure to subscribe and until next time my friends be legendary take care [Music] you