Lawrence Krauss | 'The Universe Doesn’t Care About Us... And That’s Beautiful' - Reflections On Christopher Hitchens, Physics & The Universe

Theoretical physicist and bestselling author Lawrence Krauss (A Universe from Nothing, The Known Unknowns) explores the biggest questions we can ask:
How did the universe begin? Why is there something rather than nothing? What is consciousness? And what will remain when every star has burned out?

Krauss moves seamlessly from the hard science of the Big Bang and dark energy to existential philosophy, arguing that our cosmic insignificance is precisely what makes life meaningful.

 Along the way he shares personal stories—mentorship from Nobel laureates, serendipitous discoveries, his friendship with Christopher Hitchens—and explains how curiosity and rigorous science drive human progress.

🪐 What We Cover

• 0:00 Intro & Lawrence Krauss’s background
• 1:40 Why cosmic insignificance makes life precious
• 5:45 Serendipity, creativity & the joy of discovery
• 13:00 Australia stories & reflections on public science
• 16:20 Science as culture & the power of the scientific method
• 24:30 Evidence for the Big Bang and the age of the universe (~13.8B years)
• 29:15 How astronomers measure cosmic acceleration & dark energy
• 36:00 The universe’s fate: heat death, black holes & ultimate nothingness
• 40:45 Consciousness and the mystery of self-aware stardust
• 44:40 Memories of Christopher Hitchens and Hitch’s final quip

💡 Key Ideas & Quotes

• “We make our own meaning. The universe doesn’t care—and that’s liberating.”
• “Science is not just results; it’s the process of questioning and testing.”
• “Rare things happen all the time in a big, old universe.”
• Christopher Hitchens on existence: “Why is there something rather than nothing? Just wait... it won’t be for long.”

📚 A Selection Of Books by Lawrence Krauss

• A Universe from Nothing
• The Known Unknowns
• The Physics of Star Trek
  
  

Transcript

SPEAKER_01 0:00

Lawrence Krauss is a theoretical physicist and cosmologist who taught at Arizona State University, ASU, Yale University, and Case Western Reserve University. He founded ASU's Origins Project in two thousand and eight to investigate fundamental questions about the universe and served as the project's director. So he's a great physicist, over twenty-two thousand citations, according to Google Scholar, but he's also quite the public figure. Steadfastly anti-theist and among allies the likes of Dawkins, Hitchens, Harris, Dennett, and Co. Krauss has written many books, but the one which I wanted to speak with him today about was A Universe from Nothing, which ambitions to achieve what the title suggests. How can we possibly explain and defend a claim as incomprehensible as the Big Bang? And my favorite quote of his, I like to rip off forget Jesus, it was the stars that died for us. So welcome, Lawrence.

SPEAKER_00 0:51

Okay, thanks. It's nice to uh take this walk down memory lane. I wrote that book a while ago. It's nice to see it right behind you. Um the British version, at least. Or and um yeah, sure. Um it'd be fun to talk about that. And I've been talking about politics of late. I have a new book out, which I can't help but because it came out last week. The critical. But that the great thing about the universe is it doesn't really give a damn about the vicissitudes of humans that will be gone and have made no major difference or change in the cosmos. And I kind of find that poetically pleasant.

SPEAKER_01 1:23

There's a real existential feeling to that as well. How truly insignificant might our entire experience be as an entire species, as an entire planet on the dent of the universe. And I could feel a lot of that themes of absurdism and existentialism coming from the book. I think you write about Sisyphus in there directly.

SPEAKER_00 1:42

Yeah, well, I yes, and but um but you know, it's not a it's not something that should make you sad. I I I find it I find the fact that we're cosmically insignificant so remarkable that makes us very special. And in particular, it means that we have nothing, there's no reason for us to do anything except the reasons we create. So so we make our own meaning, and we have this brief time, and it is amazing. It is truly um unfathomable that life could have evolved to the we can be conscious and and and and imagine and try and understand the universe back to the earliest moments of the Big Bang, and have been observed the universe over billions of light years, all the while stuck here on this little planet in the remote middle of nowhere. And why? And we should just celebrate that. And yeah, it'll be gone, we'll be gone. No one will know we were here, but uh, you know, when we're dead, no one you know knows, you know, it doesn't matter anymore either. So uh, I mean people may remember us, but we don't, and um, and so we should enjoy our brief moment in the sun, as I often say.

SPEAKER_01 2:50

Do you find it particularly special because it offers that worldview at least, a finite experience of time, nothing before, nothing after. Therefore, the only thing that's consequential is how you behave and you react in your own lifetime.

SPEAKER_00 3:05

Yeah, it makes every moment more precious. And there's so much, and and there's so much to know and learn. It makes every day a mo what should be a moment of discovery. So it literally makes Mike so much more precious than if there were an afterlife. Uh that the fact that we have this finite time. And it's and you know, it's it's not short, it can be pretty long for a lot of people, but but it is finite. And the the fact that uh that we go out we have one go at it means we shouldn't waste any of it if we can help it. And I say that as someone who I'm sure wastes a lot of time. So I'm trying to say these things. But you know, I'm you seem to be back-to-back appointments.

SPEAKER_01 3:43

It's been tough getting a hold of you.

SPEAKER_00 3:45

Yeah, life has been my life is oversubscribed at times, and uh my my wife has said that I I thrive in that, although I kind of wish I didn't.

SPEAKER_01 3:54

But anyway, right well, a lot of times I ever since you were graduate, have you been taken on more projects than you can handle over accelerated?

SPEAKER_00 4:03

Yeah, I think it's fundamentally because I'm lazy, to tell you the truth. Um I think it's if I'm not if I if I if I don't have lots of things, then I don't do any of them. It's sort of being able to switch gears makes it much more easy for me at times. I mean, when I'm doing something, I'm really into it. And you know, when I'm writing a book, I get progressively more into it. Or when I'm in the rare and happy moments when I've been able to do physics, I really get into it when I'm doing it. And I and and I usually in the middle of the night when there are no distractions. But um, but being able to switch around makes makes life less boring and and and means also that I'm not I don't succumb to the other wastes of time that I know I would be happy to succumb to. So so uh so it's almost insurance against that. But I so I do think I I mean I know I've accomplished a lot, but I do think it's because I I'm inherently lazy and driven, to be sure. And the only positive thing I would say uh to me it's positive, is that I I never seem to what I've done never seems to matter to me as much as what I I should be doing next. And I think that's important uh for me. I mean I'm very happy with things I've achieved, but they're not they don't satisfy me as much as doing something new.

SPEAKER_01 5:22

At the moment, what do you project into the future as that satisfaction that you're chasing after?

SPEAKER_00 5:28

I don't know. I just someone else asked me a similar similar question and I gave him the answer that I often give people, which is I don't make any predictions about the future except for two trillion years into the future. First because it's a lot easier, and secondly because no one will be around to check. But my earnest hope that my earnest hope is that whatever I imagine for my future in the in uh two years from now is not what I'm doing.

SPEAKER_01 5:50

Well, you invited so much serendipity into your life by writing, essentially. You know, presumably no one made you write. There was something inside of you that really wanted to communicate these ideas that you had accumulated over time. But it gets to the point where you're a celebrity of sorts.

SPEAKER_00 6:06

Yeah, yeah, no, and and that comes with good things and bad things, and and uh, you know, maybe it's something I crave, but happily when I achieved it, it seemed less important. Just like my PhD, I remember of Cool is Incredibly important until I got it. Um but uh uh and tenure too. Uh all of these life hurdles uh until you have them. But um I think um writing, you know, what maybe it was a calling. I I you know, I fell into a lot of things. I I I'm not strategic and I I I don't plan my life out. And I always look, I read books by scientists I admired when I was younger, and there's no doubt that that had an impact on me, you know, from Richard Feynman to Einstein to George Gamma to Jacob Brunowski. And I love that they that I loved what they did, and I love that they had that opportunity. And I recognized that, and I tell young people this who are interested in science communication. Well, if you really want to be able to communicate, first of all, if you're a good scientist, do science. Don't occupy yourself when you're younger necessarily just trying to do communication, because the more science you do, the more opportunities you'll have later on to be able to reach out because you'll have that credibility. But I, you know, I I always kind of had that. Uh first of all, if I get mad, I write. If I get angry, I write, or if I get disturbed, I write. I wrote op-eds when I was a graduate student. None of them were published, I should say, as a rule. Submitted them, and I often discovered, to my great chagrin, very similar op-eds being written by the by the opinion columnists who I said really. Yeah, that's quite an accusation. Yeah, when I was younger, I said, Why, you know, that's got the same title as mine. Anyway, but um, but I I did that, and and then I was fortunate enough to choose when I was younger uh programs that allowed me to do a number of different things. And then I was really fortunate enough to be given the opportunity to have a position at Harvard that that allowed that not only allowed me to do different things, but encouraged me. And I think that that played an important role, as did role models of mine, like Steve Steve Weinberg, Nobel Prize winning physicist, who was in my department and had taught most of my graduate courses from him, even though I did my PhD at MIT. And you know, the fact that he'd written his book the first three minutes, even in spite of being an active research scientist and a respected scientist, obviously, Nobel Prize winner, written after that when after that book came out, right after that book came out, um convinced me it might be possible to do both and gave me, I guess, mentors or at least role models. Um, and um yeah, and so I you know, I it but I fell into it. I didn't have a strategy and I and changed course many times, and and and and and it was depressing in many cases. The first book I ever wrote was I love that book, but I think it it's a it's a collector's item. And and it's and it surprises me that I had the fortitude to write another book after the disappointment of that. Totally. Of writing something and realizing it doesn't go anywhere. Um but I I still but you know, I write, I like I'm giving you too long an answer, but the bottom line is I do everything for myself, ultimately. In spite of being interested in trying to have an impact, a positive impact on the world and helping people, and I do try to do those things, but ultimately I do science because I enjoy it, and I write because I feel a need to, and I enjoy that too. So as long as I'm happy with what I've written, um that's that's in the end what matters to me. And it gives me a greater, but it has also opened a tremendous number of doors for me to do many things that I would never have been able to do otherwise, get to know people that I never would have gotten to do otherwise. Uh just being an academic, I'm just not my character, I admi I I envy many of my colleagues who are just happy going to the office and working, and and and I've never been that way. And um, and it's you know, it means that I've taken time out from my research and could have done more maybe. But um just the way I am.

SPEAKER_01 10:15

It sounds like uh despite your opening commentary on how insignificant we really are to the universe, you yourself as an individual within our small experiment, you feels like there's an ambition to at least leave some type of mark.

SPEAKER_00 10:28

Yeah, yeah, absolutely. To to have a positive impact on the world. And yeah, it's nice to think for a little, for some time people might remember what I've done, and um, and that's nice. But yeah, to have a positive impact, not because it's cosmically important, but because I think you know it's important to me. But it's I also think you know, life is not meaningless. We build the society, we have friendships, we have lovers, we have we have societies and people that need and depend on us, and uh and and therefore those meanings are real, they're not they're and we create them, but having created them, we are obliged to to to live within that context, as as Rousseau may have said, man is born free but for lives forever in chains. And those are chains of our own creation, but they're not meaningless. They just because they're they don't have cosmic significance.

SPEAKER_01 11:16

But there's that absurdum again. There is no inherent meaning, whatever meaning there is is whatever you make.

SPEAKER_00 11:22

Yeah, yeah. Well, I absurdism look, you know, one of the books that I read that had the biggest impact on me when I was younger was not just a science book, although I read a lot of those, was Catch 22 by Joseph Heller. Because that really demonstrates to me, that convinced me that the world was completely absurd. And it would be fun. Once you, you know, in my good moments where I don't get sad or unhappy or or so many of the emotions that what it's prone to, we just look at it all and say, well, it's let's let's have some fun playing with the craziness of the world. And that's what physics is for me. It's fun playing with the craziness of the world, and and writing is, and then intruding in politics is every now and then too.

SPEAKER_01 12:00

Well, speaking of the craziness of the world from physics, we're not going to talk politics, Lawrence. Absolutely not. I've been doing that all day long because I I wanted to um just tell you this anecdote uh which I had recently, which you mentioned, you know, maybe the the celebrity is something you crave, so hopefully this scratches that itch a little bit. Yeah, I was uh interviewing Robin Davidson, who might be a name that rings a bell to you. Uh she was she was with Salmon Rushdie while he was writing satanic verse. So she was in Richmond's orbit, Martin Amos's orbit. Yeah. Um which you were as well, maybe on different sides of the pond at this stage, but whatever. Just maybe it's a name that rings a bell, maybe it's not. She's a great Australian author.

SPEAKER_00 12:39

Yeah.

SPEAKER_01 12:39

Anyway, um, you know, she's uh coming into her late 70s now and she's taken up this huge interest in science. You know, she just wants to understand the world. Um fiercely atheist person. And I said to her quite selfishly, I gifted her your book, A Universe from Nothing, because I was hoping she would sort of make some notes and uh you know give me some pointers. Here are some interesting things you should be asking Lawrence. But she just looks at it and she goes, Oh boy, do I love him.

SPEAKER_00 13:08

Oh well, I love her then. Wow, I'm easily impressed. Well, that's nice, that's wonderful. Well, I I I was pleased in my life to be able to spend uh five, four or five years of my life, a lot of time in Australia. And in fact, uh in terms of celebrity, maybe because it's a small closed country, um I I I I I because I did something called QA, a program I call QA, you call QA, I did that whenever I came over. And I was very honored because they told me that Christopher Hitchens did it when he died, they wanted me to tell him. But I would be recognized a lot more almost more often in in Australia. And so, yeah, it's wonderful to hear people, especially people you admire, that you have an impact on. And and throughout my life, that's been remarkable for me. When people that I admire tremendously, when I find out that I actually not only know who I am, which is a shock, but like what I've done, and that's and I don't want to name drop, but it's been unbelievable to me when that's happened over again. And so I uh that's a great gift of having written. And I'll it's something I'll I'm a lucky man. I've had a lot of issues and problems and other things, but I'm I'm incredibly lucky.

SPEAKER_01 14:25

I think we not only Australians, but just generally um humans, we do put scientists on a bit of a pedestal because they are grasping with the the fabric of the universe in a manner that we can only aspire to do. Obviously, it's downstream of a lot of education. Maybe I don't want to say there's anything particularly special about um you know physicists and scientists and so forth, but because of that, it becomes this like uh maybe they can tell me the the answers to all the big questions that I really want to know.

SPEAKER_00 14:56

Yeah, there's unfortunately we get asked questions we can't we we don't have any ability to answer. Richard Feimer.

SPEAKER_01 15:04

What's the meaning of it all?

SPEAKER_00 15:05

Yeah, well what's the meaning or anything? And Richard Feynman's talked about he was at a party with a bunch of generals, and by the end of it, he was giving them advice about subjects he knew nothing about. So I try to avoid that. I'm I'm susceptible to that. But it but I do recognize that, and I I don't try and take advantage of it too much. But yeah, people have a certain awe because people because they're the same questions everyone deals with. The questions in in the Universe of Nothing, I wrote a book more recently called The Uh Known Unknowns, as it would be in Australia. Um, and it's about what we know, we don't know about the universe. And the questions, the questions, the outstanding questions in physics and science are the same questions that everyone asks themselves. How did the universe begin? You know, what you know, what's the nature of time? Are we alone? You know, how did life originate? What's consciousness? These deep questions. And so I think we are for I'm extremely fortunate that I got paid to play with those deep concepts, and it's a privilege, not a right. And um, and but it is unfortunate. You say that everyone puts pines on a pedestal, and they have traditionally. Scientists were have been among the most respected group, if you look at, or most trusted group, anyway, in society. Unfortunately, and one of the things that reasons I wrote this new book is that's changed a lot, at least in the in the United States, and I think in the West, suspicions about science after a number of things like COVID. Um, and I and it's unfortunate because I think science is special, not because it's better than literature or music or or or art, all of which I love, and I might I point out that they're all the same. They're all part of human culture that give us a different perspective of who we are and where we came from. But but science works, and and and the scientific method is what's what's worth extolling, not the results of science only, although they're fascinating and amazing and unbelievable. The universe is more amazing than we can imagine. So I'm I'm, you know, some people accuse me of scientism, but the scientific process is part of all of life and and is essential. No knowledge comes by revelation. The scientific process involves questioning, testing, retesting, questioning again, relying on empirical evidence, using rationality, and that's part of everything. Part of you know, part of music, part of part of part of art. And you know, I'm I was at an event once with my friend, my a friend of mine, um uh a um an actor, Alan Alda, and uh he um he was speaking and and he said uh you know, art requires precision, and science requires imagination. And I love that because he put them on their head. But you know, that the and I again I said this recently, uh probably even today, but but I think people don't appreciate science uh in a way that they should, because science produces technology technology. And therefore, if there isn't technology associated, people say, what's the point? What's the point of asking how the universe began or what the shape of the universe is or what how it'll end? But they never ask that of a of a of a of an Eric Clapton riff or a Picasso painting or or uh Shakespeare and but it's those it's there what science shares with all of those is exactly that the enrichment of the human spirit, raising us up from the from from the tragedy of lack of consciousness, and also um uh addressing the fundamental questions of existence and causing a different perspective. Just like you can be jarred by a great movie, you can be jarred by learning something of the universe, and whenever you do, that surprise is what makes life worth living.

SPEAKER_01 18:45

And also I suspect the serendipitous outcomes of trying to answer these large questions about you know, where did the universe begin or how do we measure the distance between this accelerating star from another? Uh, there's a great line in the book where you wrote that um I my own early, I'm speaking in your voice now, my own early prediction for the existence of dark energy was that it was absurd and ridiculous. But like Fleming's Petri dish, you know, something just sort of stumbled out of nowhere, and this serendipitous discovery can lead to a whole new range of questions, which we cannot predict into the future. We cannot project to say what the outcomes of those discoveries are going to be. We just know that they're going to be able to do that.

SPEAKER_00 19:25

Yeah, and they're gonna be not what you expected because the universe as the imagination of the universe is far greater than our own. So I like to say every day, I'm surprised if I'm not surprised. And yeah, and that that that realization about dark energy, you know, it because it was so crazy, I I only publicized because I like to be a heretic, and and I I was sure it meant there was something wrong about the observations. Well, it turned out the observations are right, and some people actually tried to prove me wrong, a few of them, and then others I didn't even know if they were aware of it, although I think they were, even though they claim they weren't, including my good friend in Australia, you won the Nobel Prize later on for confirming it.

SPEAKER_01 20:00

How often do you see serendipity drive research?

SPEAKER_00 20:03

All the time. And but you but but you know, what you have to realize is most of the time you're wrong. It's it requires it requires if every time you had an idea was right, anyone could do it. And so it requires a certain um uh a certain will uh uh a certain well dedication, I guess is one way of putting it, but uh a willingness to to be wrong and be disappointed a lot. Because most good ideas are wrong. And most things you try are wrong, and you just have to keep plugging away. And um and and it requires something. I don't know what it requires. Pigheadedness in some sense. Well, you have to believe. Well, one of the reasons is you have to believe what you're doing is right. That's okay. But the difference between that and religious faith is that when shown wrong, you have to just say, okay, I forget about it. So I I think it's right, and I'm gonna work on it. Oh, it's wrong. Okay, let's move for move on to something else. And that that's what makes science different than religion.

SPEAKER_01 21:00

One of them is or until you keep plugging away and some empirical evidence is discovered under the surface.

SPEAKER_00 21:06

You can't for instance and and and sometimes it leads you, well, it's the same as business. I created a master's degree in put physics entrepreneurship once, and the business school dean said it was noxymoron, but he didn't realize that physicists are entrepreneurs. Because, like entrepreneurs, you try something and it fails, but what you you what you get out of that is you realize, oh, there's another problem. I was using this to solve this problem, but you know what? There's another problem that it solves, and that's that's business, but it's also physics and all of science.

SPEAKER_01 21:33

It seems like quite a long bow to draw the the analogy between a physics day-to-day job and an entrepreneur's day-to-day job.

SPEAKER_00 21:41

Well, it's I mean, you well, no.

SPEAKER_01 21:43

Maybe more like a venture capitalist.

SPEAKER_00 21:44

There are many things that are true, both. Most of the time they fail, they learn from their failures, and they move on and and and do other things. And um and they're well difference between an entrepreneur and a physicist, or at least is it like the difference between An experimental physicist and a theoretical physicist. Because I can I can propose lots of things and then I can move away. The experimentalist has to make it work. And the hard part I learned about entrepreneurship is not having a good idea. It's making it work in in the business world. So I guess it's not as I don't see them as disparate as one might think. Because I think the same tools are I that's why I think a physics degree is wonderful for anyone, because it gives you, you know, most of them are pe people who take physics, they're not going to become physicists, but they're going to hopefully use those tools. We used to say to students that what's great about physics is it lot it teaches you how to answer a question when you don't know what the question is.

SPEAKER_01 22:41

Some of the best physicists now are going to Jane Street and Rentech and one year when I taught at Yale University when our entire PhD graduating class of five people in theoretical particle physics all went to Wall Street.

SPEAKER_00 22:57

Did that disappoint you? No, I mean, no. Well, it disappoints you when I see someone who I think had had great, great potential as a scientist to continue to go to Wall Street. And that me once, actually, I was just talking to him yesterday, a student of mine from ASU, who was great and decided for a variety of reasons to move to New York, and I'm glad he's happy there. But I he would have made a great career in science, in my opinion. Um, so no, but I think you know, I think people should follow their desires, and there's a lot of and the tools, if they use the tools that we try taught them, and I don't even think they that they taught themselves. I I I think I I I don't suffer under the illusion that I teach a lot. I think I just motivate people and give them some direction. The good ones teach themselves, and the and the good ones are the ones who are doing their PhDs, hopefully with me. But anyway, um uh so the tools that they learned on their own often, if they can use them for other things, all the better. Uh Wall Street is, you know, the least interesting of things. I mean, make just making money seems to me to be the just for the money's sake, me seems to me to be the least interesting thing you can do, but that's alright, you know. Anyway. Alright, well, Lawrence, we gotta talk some science. So speaking of I've talked a lot, I've skirted around it for for uh 27 minutes, plus including a little downtime. But anyway.

SPEAKER_01 24:24

But regarding the core of the scientific method, it requires empirical evidence to test the theory. What empirical evidence do we have for the Big Bang and the age that you suggest the Big Bang is?

SPEAKER_00 24:36

Well, the great thing is that we have uh the a host of it doesn't all come from one thing. So I have people write me all the time saying, well, this is wrong, and but they don't realize it's just it's just one piece of a puzzle. First of all, the simplest thing is the universe is expanding, right? We measure that. And we measure the rate of its expansion. And you work backwards, and we first used that you used to give us an upper limit on the age of the universe. Why? Because gravity sucks, right? Because if gravity is always attractive and the universe is expanding, it means it's slowing down. Well, that means it was moving faster early on. And that means if you take the present rate of its expansion and just extrapolate it backwards, you'll get an upper limit on the age of the universe, right? Because it would have taken less time for some stuff, two stars to get this far apart if once they were going faster than they are now, right? And so that gives us an upper limit on the age of the universe. And working backwards, you get you get, you know, something depending upon the expansion age, you know, uh uh depending on what it was, anywhere between 10 and 20 billion years. It's amazing to get the right number. The Hubble constant, which is the rate of expansion of the universe, is probably one of the most fundamental constants in nature because it gives us it, it more or less explains so much about the character and quality of the universe. Our universe would be very different if it was a million years old instead of 13 billion years old. And and anyway, so it's a very important number. But um, but all that turned out to be wrong. And one of the things that got me into the cosmological into dark energy was the realization that when we there was a something that was a little disturbing. And that is when we determined the age of stars, they appeared to be older than the age of the universe, which is a problem, right? Um and and we can get into that later. But so they that that was one way to determine the age of the universe. But there are other ways. For example, the universe has been cooling down, and we can look and measure and see when the universe was 3,000 degrees, something called a causing microwave background. And we can now measure that background and see that it's three degrees or 2.734 degrees Kelvin above absolute zero. And we know the laws of physics tell us how radiation cools down as the universe expands, how how it cools down as a function of time. And when you work out the age of the universe there, you get the same order of magnitude number. You get billion, you know, 10 to 20 billion years. Again, and if you look at the age of stars, you don't get look at the oldest stars, you don't find out they're a million years old or a trillion years old, you find out that they're about 10 to 20 billion years old. Now, whether it's 10 or 20 billion is where the problems come in. But until it's the age of individual stars. It's quite a modular for error. You know, yeah, yeah. The age of individual stars, which because we know how stars work and we can model them in computers, we can measure them, we can look at our sun, we know it's 4.55 billion years old, where all the decimal places matter. Um, and and uh and so the age of stars, the cooling, the temperature and age of the universe from from there, the expansion rate of the universe are just three examples that all point to exactly the same number and all tell us that the universe is now we know 13.8 billion years old, and there was a big bang.

SPEAKER_01 27:48

The chapter in the book where you describe how you um well maybe not you, but how physicists measured not only the rate of acceleration, but the sort of arc that it would be accelerating on was just absolutely fascinating.

SPEAKER_00 28:04

Oh, good, yeah. No, I didn't happily I'm a theorist, I didn't do any measuring, but I did tell them what to well, I I think I pointed out the significance of making that measurement. But um, it's hard work, and the measuring is hard. And that's why I don't believe them with a Nobel Prize, because they did the hard work of doing the measurement.

SPEAKER_01 28:20

Give us the skinny in layman terms, how just through looking through a telescope we can make these types of astronomical calculations. Well literally.

SPEAKER_00 28:31

Well, it relies on on a lot of tests that you need to be convince yourself you're not making mistakes about. But but but the first one is um Hubble measured objects and found out this one famous Hubble law that that objects that are twice as far away from us are moving twice as fast, objects that are three times as far away from us are moving three times as fast. And we can and and and I, as I show in the book, that directly tells us that the universe is expanding. Not that we're the center of the universe, so because every place is the center of the universe, basically, or no place, depending upon your mood. So um, but but of course, that's true nearby, and by nearby I mean up to a ten to a hundred million light years away. Um but if the rate of the expansion of the universe has been changing, then the distance uh uh if you look at an object that's moving at a certain rate, and you move its, you measure its velocity away from us, and you measure its distance away from us, that'll tell you whether it's been speeding up or slowing down. Right? Because if it got further away than than than you'd than you'd think, then maybe it's been traveling for longer and it's further away now. Okay? And um and so how can you do that? Well, you can look at objects and try and measure what their speed is away from us and their distance, and that's both are hard. How their speed away from us is not so hard because we have this thing called the red shift. If you look at objects and they're moving away from you, the the frequencies of all the light they emit get stretched into the red. And light and stars all emit characteristic frequencies, as do as do other objects. But the problem is you can't see individual stars very far away. So you look for, in this case, what what was done, and it's the first thing that was done, but we've since done many other ways of measuring this, was to look for the brightest objects in the universe, supernovae, exploding stars. And what was discovered, which was very interesting, was first of all, supernova have characteristic uh frequency distribution of light, and and and so you can measure their and also they are located in galaxies, and you can measure the redshift of some of the stars in those galaxies sometimes, or the galaxy itself. But but looking at the supernova, you can all you can also try and infer its velocity. Because it's very bright, you can see it far away, so that you can begin to look at these very small effects where the change, where the rate of motion of things has changed over cosmic time, billions of years, not millions of years. But the thing that was really it really changed the game was the realization that, well, you could tell how far away they were. How far do you know? How do you tell how far away an object is? You can't take measures across the universe. And the way we use it is to say, well, if I look at the light bulbs in this room and I know they're 100 watts, which they're not anymore because they're LEDs, but um, but say I had a hundred watt light bulb and I had a light meter here and it measured one watt, I'd be able to say how far, and I knew the light, the intensity of light fell off one over r squared, I'd know how far away the light bulb is. So it would be great if the universe were populated by 100 watt light bulbs. It's not. But supernovae become the equivalent because it turned out by nearby supernova, where you could measure their distance by independent means, it turned out that there was this relationship, but no one no one understood for a certain type of supernovae called type 1 A supernovae, that the length of time they remained bright was directly related to their intrinsic brightness. So if you could just measure a supernova and see how long it remained bright, you knew how bright it was intrinsically. And then, of course, you look and say, how bright does it appear? And that would tell you how far away it is. And so that was the that was the job. First of all, discovering the empirical relation and making it very precise, even though no one knew it, and then making sure that that there weren't other things in the way, like dust that's getting in the way of what the apparent brightness of something is, and then going out and finding the damned supernova. I mean they supernova occur once per galaxy per 100 years. So they're not very frequent. But if you look far enough, if I look far enough in a if I take a don, well, what what's your smallest unit of Australian currency? Uh a cent. A cent? Okay, good. I thought so. If you take a cent and you hold it up in the night sky, and if you look deep enough, you'll see more over a million or maybe a hundred million galaxies in that region. Certainly a million. And um, and that means if you're willing to be careful enough and look deep enough, remember, if it's once per hundred years per galaxy, if you see a hundred galaxies and you wait a year, you're gonna see one. You know, if you if you if you measure uh ten times that uh you're gonna see one a month. Okay, so you measure a thousand galaxies, and if you measure a hundred thousand galaxies, you're gonna make, you know, you're gonna see one every few days. And so the idea is to look at fields of large number of galaxies and see an exploding star every day or two. And then, if you're lucky and it's far enough away, that's the other thing, you know, far enough away, then you can try and measure these things, and it's a hard job. But when they did that, they discovered look, if the universe were slowing down as everyone thought, then things would, then you know, the distance redshift curve would bend down in the in the in the language of this. And what they discovered was it bent up, which meant the universe was speeding up. And it was speeding up by exactly, I would happy to say, the amount we predicted it should be speeding up based on other observations. But that means that's strange, because gravity sucks. But it turns out if you put energy in empty space, it's the only thing that's gravitationally repulsive. And so energy in empty space would cause the expansion of the universe to speed up, which suggested that empty space had energy and just the right amount that we needed to explain a lot of other stuff. The stuff that we my colleagues and I looked at. And it's shocking that it all worked out so beautifully, and it I surprised the hell out of me. But I said, I think I said the first time I didn't believe in dark energy was when they observed it, because it all just seemed to work out so beautifully.

SPEAKER_01 34:57

Pinch yourself moment.

SPEAKER_00 34:58

Yeah, and it made me very happy to, you know, there aren't many times in your life when you think you might be the first person to realize something fundamental about the universe. So I was very happy to have that experience at least once. I've had a lot of experiences where, you know, if the universe had been smart enough to obey to listen to my ideas, then, then, then it would have been true about us. This was one time when it worked.

SPEAKER_01 35:23

You you made a quip earlier about um us thinking we're the center of the universe here on Earth. But if you can measure the distance and accelerating uh distance of various stars, is there any conceivable way to measure that center of the universe from where the Big Bang started?

SPEAKER_00 35:38

There is no center of the universe where the Big Bang started. The Big Bang started everywhere in space. It's but doesn't it expand outwards like that? No, no, no. You have to think of this. I'm sure I talked about it in the book, but the analogy I will give you is that balloon, which is expanding. Okay? But forget the center of the balloon. You know, the balloon is embedded in three dimensions, but just think of the surface of the balloon, and that's the universe, just that two-dimensional surface. There is no center of the earth. You know, every place you Australia may think it's the center of the earth, and New York may think it's the center of the earth. But there is no center on the surface of the earth. And and yet if the earth were expanding, if it was a balloon, every place would be moving away from everywhere else. And there was no center. The Big Bang is happening everywhere. Space is expanding. And so every place you are looks like the center of an expanding balloon. If you look outward, you'll see exactly what Hubble, Mr. Hubble, saw. All the objects are moving away from you, and those that are twice as far away from you are moving twice as fast, and etc., etc. So there is no center, and it happened everywhere. It just all was much smaller, and all of space once occupied an infinitesimally small region, which is itself unfathomable to imagine. One book I wrote called Atom begins when the entire universe was the size of an atom. And all of the energy, and much more energy, in fact, because some's been lost. Um, if all the galaxies and all the stars and all everything was all contained in a region the size of an atom, it's hard to believe that that was once the case, but but it was.

SPEAKER_01 37:08

No, it also, you know, and when it is presented like that, it does sound completely science fiction and it sounds a little bit, you know, religious as well. Equally unbelievable.

SPEAKER_00 37:17

It's amazing as you can say, well, if that were the case, what would we predict? And what's amazing, well, we can't measure it all the way back to when it was the size of an atom yet. Maybe we can make some measurements and I propose ways to do it. But we can certainly, you know, take the history of the universe back to the first millionth of a maybe a millionth of a second of the universe when the size of the universe was was once at least much smaller than the size of our solar system. On all of the energy of the hundred billion galaxies, each containing hundred billion stars, was contained in a region that small. So we can go back a long way and empirically say, if that's true, what what could can we measure? We can measure lots of things, not just the nature of the large-scale universe, but the elements, the light elements. We can use nuclear physics to say how much helium should there be, how much lithium, and the numbers work out. The Big Bang really happened.

SPEAKER_01 38:07

And what about the question of the finite time of this universe? The fact that it will eventually come to a point when every star has imploded on itself, the supernova has has left the memory of the galaxy. Could it be the case that there is a finite time for all this as well?

SPEAKER_00 38:23

Well, it's not, look, it's going to be very long. The universe itself can go on expanding forever, and based on current evidence, the best bet is it will. But um but the time is unbelievably long. The longest lived stars on main sequence stars, like our sun, but not the size of our sun, will live two to ten trillion years. Trillion years, a thousand billion years before they burn out. Okay, and then and then uh you know, over an unimaginably longer time, galaxies containing those dead stars they'll they'll collapse into mammoth black holes. And then over an unimaginably longer time, like 10 to the 50th years, I mean, you know, 40 orders of magnitude longer than the current age universe, those black holes will evaporate, leaving the universe cold, dark, and empty. So it's a long time. But it's miserable. Like to say, the future is miserable, and so we should enjoy what we can.

SPEAKER_01 39:22

Exactly. All we have is the time allotted to us over the next couple of years.

SPEAKER_00 39:26

We live in a very interesting time. I mean, you know, and of course, I think one would say that regardless of the time one lived in the universe. Yeah, people would always be saying that.

SPEAKER_01 39:33

Yeah, but maybe perhaps our own centric, self-centered perspective of the world makes us really do feel on our bones this is perhaps the most interesting time to be around. But look, I want to be respectful.

SPEAKER_00 39:45

I think it is it is the most interesting time to be living in the universe, but I also think that's time invariant.

SPEAKER_01 39:52

Lawrence, I want to be respectful to the time that you've allotted today. So just a couple more and we'll get it quick. Again, it's up to you for how terse or verbose you want to be in the response. So something I've observed in a lot of your lectures and then as well in the book, is you do want to at least talk about this philosophical question about what is consciousness. And there is this um amazing quote from Ray Bradbury uh that we are the universe introspecting stardust trying to make sense of itself. Since if you are to believe that we are that we are the product of I don't believe anything, the evidence is what we are stardust, yes. But beyond all of that, like how how do how are we supposed to make sense of the cosmically impossible randomness of the fact that we might be here, whatever evolved species we become, able to communicate these ideas to each other, but perhaps the exact same substance we're trying to observe.

SPEAKER_00 40:47

It's it is amazing, right? But one of the ways we can understand is the universe is big and old, and rare things happen all the time. You know, it's 13.8 billion years old, there's a hundred billion galaxies, a hundred million stars, and we, you know, maybe we're the only life in the universe, I suspect not. But even though it's incredibly unlikely that we would be here, the universe is old and rare events happen all the time. As I say, supernova expend once per 100 years per galaxy, but if you look out over the universe, there's a supernova going off every second. And and so um uh uh it is amazing and fortuitous for us especially that we have that this stardust has somehow come together and and through evolution and and and time and natural selection produced something that can ask these questions about itself and the universe in which it exists. It is amazing. I would call it a miracle, but I don't want to because there are no such things as miracles, but it's it seems miraculous. But um, but it but uh but it is but uh you know in my last book, I I my last chapter, not the yeah, the last book before this, the the the known unknowns, it's all about consciousness. And I'm you know, that's too, and I point out that that's just a we don't understand consciousness at all. I'm just a simple physicist and I deal with the easy things, like the universe. Not I mean consciousness is just so unbelievable. We don't even know what consciousness is, much less how it arose. I'm convinced of that after studying it a lot for that book. And so it is an open question and a wonderful one, and maybe an eternal mystery. I suspect we'll learn about consciousness when we create it, as I say in my book. But maybe eventually if we create conscious entities, we'll learn how consciousness evolves. Maybe. And um, but it is amazing, and we should celebrate it and not waste it, and not be afraid of it, and not be afraid of asking the questions about the universe, not being afraid that the universe is strange and maybe meaningless and doesn't care about us. Well, not maybe meaningless, apparently meaningless, but certainly doesn't care about us. And and that shouldn't make us sad or afraid. Instead, we should say, aren't we lucky that the stardust that coalesced into the earth eventually over four and a half billion years creat allowed the evolution of minds that could have a discussion like ours, could build telescopes to look back to the beginning of time, and uh particle accelerators to explore the fundamental structure of matter, and that can love and that can make music and can write poems and you know, etc.

SPEAKER_01 43:15

Finally, Lawrence, um an old friend of yours who was supposed to write the introduction to this very book, Christopher Hitchens, uh was uh too sick to do so. You hosted last year an event for him called Hitchmas. Uh so he clearly meant a lot to you, yeah. Uh maybe not only on a personal level, but uh I I'm I'm projecting here. But the way that myself and a lot of people did admire him, his superb oration and clarity in speaking about these topics. So uh as the final word, I just wanted to ask you about Christopher Hitchens and particular memories that stood out to you that really exemplified the matter.

SPEAKER_00 43:55

Well, I've lots I gave a I gave I was honored to be asked to give the uh Memorial service in New York City, and you can see it online. Give the speech about Christopher, and I'm not gonna repeat all of that here. But it was a I was honored and I had many interesting experiences with him, including right very close before he died, where I announced that to someone I was his personal physicist, and that was a wonderful thing. But but I will say something about the about his the foreword that he never wrote because it was he wouldn't let me publish half of it. You know, he wanted to be finished. But but he gave the best answer to the question of why is there something rather than nothing? Not the best, but one of my favorites. I may say it in the book, I'm not sure if I do, it's been so long. So what I point out in the book is the far in the far future of the universe, is what I told you. Eventually the stars will die out, black holes will form, black holes will evaporate, the universe will be cold, dark, and empty. And if we wait long enough, all of the stars, we even before that, all of the stars we now see in other galaxies will disappear because they will be moving away from us faster than light. So our galaxy will be alone in an empty void, just like the one we thought we lived in a hundred years ago. But eventually it's all gonna be gone. So so Christopher said, you know, why is there something rather than nothing? Well, just wait, there won't be for long. And and I think it's all gonna be nothing again, and I I like that.

SPEAKER_01 45:20

Nice one, Lawrence. Thank you so much for being so generous with your time today. Is there anything else you wanted to bring up?

SPEAKER_00 45:26

No, I had no agenda. And uh I thank you. It was fun, and and uh and we and that we went on this long as a tribute to the uh quality of the questions because I'm tired. So thanks. All the best, Lawrence. Thank you, mate. Okay, take care.