Speaker 1: Imagine the day the Aliens finally arrive. Maybe you're picturing
Speaker 1: an invasion, ramps dramatically unfolding from gleaming ships, snarling tentacled
Speaker 1: monsters slithering down rapidly, overrunning Earth's meager defenses. And yet
Speaker 1: that's fair. We're as likely to be unceremoniously fried into
Speaker 1: human crisps by a planet wide death ray as anything else.
Speaker 1: But this is seeing the alien arrival glass as half empty. Instead,
Speaker 1: let's look at the glass as half full, even if
Speaker 1: we aren't sure yet what it's full of. Maybe aliens
Speaker 1: have figured out the answers to puzzles that remain impenetrable
Speaker 1: to us, like what everything is made out of at
Speaker 1: the smallest level, or why time only flows forward, or
Speaker 1: how big the universe is. What if aliens know for
Speaker 1: a fact how our universe began and how it all
Speaker 1: might end. What if they know what it's like inside
Speaker 1: a black hole, or actually understand quantum mechanics like the
Speaker 1: back of their tentacle. Maybe to them, the universe isn't
Speaker 1: a place of consistent mystery, but one that tindly follows
Speaker 1: some basic rules. And what if they could just tell
Speaker 1: us how everything works? So we don't have to blindly
Speaker 1: hack away for decades or centuries to gain this elusive knowledge.
Speaker 1: They might carry the product of millions or billions of
Speaker 1: years of alien scientific thought to catapult us unimaginably far
Speaker 1: in our quest to understand this wonderful, bizarre, violent, and
Speaker 1: beautiful cosmos. If our species met up, physicists hope that
Speaker 1: we'd be able to geek out together, sharing notes on
Speaker 1: this glorious galactic journey of discovery. But could that really happen.
Speaker 1: A lot of scientists, especially physicists, believe it. Could. They
Speaker 1: imagine that unraveling the secrets of nature is a universal
Speaker 1: project that would be shared by the scientists of alien
Speaker 1: species across the galaxy, and that physics describes everything in
Speaker 1: the universe, not just life on Earth, and so should
Speaker 1: also form the foundation of alien science. Therefore, we should
Speaker 1: be able to use physics as a mental bridge between
Speaker 1: our species. But hold on a second. Are we accepting
Speaker 1: those arguments too quickly? Have we really given the question
Speaker 1: careful thought? Or are we blinded by our fantasy of
Speaker 1: galactic scientific cooperation and the narrowness of our own experience.
Speaker 1: We have only our one example of science here on Earth,
Speaker 1: so it's hard to be sure how much of it
Speaker 1: might be colored by human nature and culture. Are human
Speaker 1: physics and math the only way to think about the
Speaker 1: universe or are they just the only way we can
Speaker 1: imagine it. Are the laws of physics something universal, something
Speaker 1: we have discovered, or are the human something we have invented.
Speaker 1: Welcome to Daniel and Kelly's Extraordinary Alien Universe.
Speaker 2: Hello. I'm Kelly.
Speaker 3: I study parasites and space, but I don't think about
Speaker 3: aliens as much as Daniel does.
Speaker 4: Hi.
Speaker 1: I'm Daniel. I'm a particle physicist, and I do want
Speaker 1: to figure out the secrets of the universe myself, but
Speaker 1: I'd rather just download them from alien brains if possible.
Speaker 2: Yeah, that'd be nice, all right.
Speaker 3: So my question for you, Daniel, when you think about aliens,
Speaker 3: which is apparently all the.
Speaker 1: Time, embarrassingly high fraction in my brain?
Speaker 2: Yes, that's right. That's right.
Speaker 3: For someone who's not like a conspiracy theorist or a
Speaker 3: cryptid fan, you think about them a lot.
Speaker 1: You're making some assumptions there.
Speaker 3: I've known you for a while, But when you imagine aliens,
Speaker 3: what do they look like in your head?
Speaker 1: Oh? Boy? Wow? You know I think it's almost impossible
Speaker 1: to anticipate what aliens actually look like, or at least
Speaker 1: I hope. So you know this two scenarios. One is
Speaker 1: aliens show up and they're basically star trek, you know,
Speaker 1: they're humans with fuzzy foreheads or you know, just some
Speaker 1: little tweak on the kind of life we have here
Speaker 1: on Earth. The other scenario is they show up and
Speaker 1: they're so much weirder than we could ever possibly imagine,
Speaker 1: And that, to me is the fascinating scenario. That's the
Speaker 1: non Starbucks scenario. You know, it's like, you don't want
Speaker 1: to travel the world and discover Starbucks on every corner.
Speaker 1: That's boring. You have Starbucks at home, says you. I mean,
Speaker 1: I like Starbucks too, but I prefer like local, weird coffee.
Speaker 1: That's why I go traveling. And so if aliens show
Speaker 1: up and they're not really weird, I'm going to be
Speaker 1: disappointed in the universe.
Speaker 3: Quick side note, When I travel, I do like to
Speaker 3: go to the McDonald's and other countries because but only
Speaker 3: because I like to see what other stuff they have
Speaker 3: on their menus, you know, because they usually don't have
Speaker 3: like the US standard menu, and I like to see like, oh,
Speaker 3: what's the how did McDonald's homogenize with this culture to
Speaker 3: create something new? But also confession time, Zach and I
Speaker 3: were in Versailles for our honey and we had this
Speaker 3: lovely breakfast and we went to go throw away our
Speaker 3: receipt in our trash and I noticed a McDonald's arch
Speaker 3: and I was like, wait a minute, and it was
Speaker 3: it looked so nice. We didn't realize we had gotten
Speaker 3: breakfast at McDonald's on our honeymoon and it was delicious.
Speaker 2: We had a great time.
Speaker 1: In your defense, McDonald's in France is really a different
Speaker 1: kind of thing. Yeah, it really is much more upscale, absolutely.
Speaker 3: Well, and that's like a cultural insight or something that
Speaker 3: I feel like you get by visiting the McDonald's. But
Speaker 3: anyway else I don't exclusively eat at McDonald's.
Speaker 1: Well. I went to a conference in TYPEI once with
Speaker 1: an Israeli colleague and he ate every single meal at
Speaker 1: Subway or McDonald's and like, this is Type AI people.
Speaker 1: I mean, the food there is incredible. I was a
Speaker 1: vegetarian at the time and we had this nineteen course
Speaker 1: banquet dinner and they served me a separate, different vegetarian thing.
Speaker 1: For each of the nineteen courses, and each one blew
Speaker 1: my mind, Like the food there is unbelievable. Plus I
Speaker 1: also went to the night market and like all sorts
Speaker 1: of weird stuff that probably had eyeballs in it. But
Speaker 1: to me, that was the joy of it, right. But
Speaker 1: he was like, yeah, no, I'm not touching that.
Speaker 2: But hold on.
Speaker 3: If you're a vegetarian but you eat eyeballs, is that
Speaker 3: like an eyebolitarian like a pesetarian only eats fish.
Speaker 1: Well, I was a vegetarian at the time, but I
Speaker 1: also wanted to explore, and I was at the night
Speaker 1: market and I couldn't speak the language, so I took
Speaker 1: some risks. And I'm not sure whether or not I
Speaker 1: ate eyeballs. I think probability Daniel ate eyeballs that evening
Speaker 1: fifty percent.
Speaker 3: Yeah, good, good on you. It's good to try new awesome.
Speaker 2: Yeah.
Speaker 1: Anyway, the joy of traveling is exploring the universe and
Speaker 1: having your mind blown by how surprising it is, by
Speaker 1: breaking out of the box of your expectations.
Speaker 3: Absolutely, and you always are so great at transitioning us home.
Speaker 2: And so here we are today.
Speaker 3: We're talking about the joy of studying physics and we're
Speaker 3: trying to nail down on the philosophical question. Is physics
Speaker 3: discovered or invented?
Speaker 1: Yeah, exactly, it's the physics that we have developed here
Speaker 1: on Earth. Are we figuring out basic rules of the universe?
Speaker 1: Or are we just telling a human story one that's
Speaker 1: approximate and effective and kind of only makes sense to us.
Speaker 1: And this is a philosophical question for sure, but I
Speaker 1: like to think about it in concrete terms and inject
Speaker 1: aliens into it by imagining the scenario that aliens arrive
Speaker 1: and we try to talk to them about this because
Speaker 1: that's when it matters, right, And might think who cares
Speaker 1: if it's discovered or invented, it works, right, But number one,
Speaker 1: I'm curious about whether it's really deeply true. And also
Speaker 1: I am concerned about this situation. What if aliens show
Speaker 1: up and they have these answers but we can't make
Speaker 1: a scientific connection with them. That would be so frustrating.
Speaker 1: And that's why I wrote my new book, Do Aliens
Speaker 1: Speak Physics? Out November fourth from Norton and available at
Speaker 1: all fine bookstores. Please go check it out.
Speaker 3: Okay, so you said that it would be a real
Speaker 3: bummer if the aliens got here and we, like you know,
Speaker 3: hadn't figured out the truth. Is that because you're worried
Speaker 3: about what they're gonna think of us, In which case
Speaker 3: I have a speed that I tell my daughter about
Speaker 3: why you shouldn't worry about what other people think. Or
Speaker 3: is it because it would inhibit our ability to communicate?
Speaker 1: In that case, my fantasy is that the aliens deliver
Speaker 1: to us answers to some of the puzzles, you know,
Speaker 1: like I just want to know what is inside a
Speaker 1: black hole? What is the real story of the universe.
Speaker 1: I would love to know the answers to these questions.
Speaker 1: And the idea that aliens have these answers out there
Speaker 1: is endlessly frustrating to me. If they could just show
Speaker 1: up and give them to us, you know, like somebody
Speaker 1: knows the truth, please just share it with us. So
Speaker 1: my concern is that they show up and we're mismatched
Speaker 1: somehow so that we can't get those answers. Maybe we're
Speaker 1: not smart enough to understand it, or maybe we're going
Speaker 1: down a different path, or maybe they have a different
Speaker 1: way of explaining these things, or maybe they're asking different questions,
Speaker 1: you know, they perceive the universe differently. And they're not
Speaker 1: interested in the questions we're asking, and so I'm worried
Speaker 1: about these scenarios where we're mismatched with the aliens, and
Speaker 1: so we can't have that moment of scientific cross emogenation.
Speaker 3: I mean, do you think it's possible that we're on
Speaker 3: the right track and they're not, or if they get
Speaker 3: to us, then they must be on the right track
Speaker 3: because they're doing stuff we can't.
Speaker 1: That's a great question. I think if we're on different tracks,
Speaker 1: that probably says something about the nature of the universe.
Speaker 1: If he can be described in different ways, then maybe
Speaker 1: there is no one truth and you can't say who's
Speaker 1: on the right track or the wrong track.
Speaker 3: Well, when I'm interested in finding the truth, what I
Speaker 3: do is I reach out to the extraordinaries.
Speaker 2: And so that's what we did.
Speaker 3: We reached out to our listeners and we asked, are
Speaker 3: the laws of physics discovered or invented?
Speaker 5: I think that lots of physics are somewhere in between
Speaker 5: an invention and discovery.
Speaker 1: Maybe closer to the discovery I will help.
Speaker 4: And Einstein didn't invent space time doing its bendy, squishy,
Speaker 4: stretchy thing. He just caught it in the act, so
Speaker 4: definitely discovered.
Speaker 6: Our curiosity and need to understand the world around us
Speaker 6: has led us to discover the laws of physics, and
Speaker 6: we've had to invent tools to help us do that,
Speaker 6: both abstract and physical. So it's a little bit of both.
Speaker 6: It seems it's some of both.
Speaker 1: There are realities in the universe that we can discover,
Speaker 1: and then we invent models to describe those realities.
Speaker 4: Surely the laws of physics discovered because they already exist.
Speaker 7: I think they are discovered. I think it's a little
Speaker 7: bit of both. I think they're invented as we're kind
Speaker 7: of putting the bits and pieces together, and then the
Speaker 7: more we can understand it, the more we are discovering
Speaker 7: how things actually are.
Speaker 4: So the laws of physics are certainly discovered, while the
Speaker 4: maths used to describe them, or human inventions.
Speaker 6: The laws of physics are of course discovered, but defined
Speaker 6: in our language as humans and correct.
Speaker 1: It's discovered, Otherwise it's invented because it's not correct. It
Speaker 1: doesn't seem to make sense to me to say that
Speaker 1: we invented gravitying.
Speaker 2: I would say that the way things are is discovered,
Speaker 2: but the methodology by which we use to measure and
Speaker 2: categorize in our own terms is invented, but.
Speaker 4: The laws of physics help us make order and meaning
Speaker 4: from what we discover. But they're not immutable, so in
Speaker 4: that sense they're invented and can change as new things
Speaker 4: are discovered. I would say, while the fundamental mechanisms how
Speaker 4: physics work are discovered, the laws of physics are invented.
Speaker 2: They are useful and necessary for set mechanisms to make
Speaker 2: sense to our big monkey brains.
Speaker 4: I think the observations of the universe are constant, but
Speaker 4: how we describe them as laws depends on our particular
Speaker 4: moment in history and the mathematics available to us at
Speaker 4: the time.
Speaker 2: I think they were both. I think the laws of
Speaker 2: physics were first discovered and then we invented the mathod
Speaker 2: to goal with what we discovered.
Speaker 5: The laws of physics must be fundamental and the way
Speaker 5: we do Oh, there goes the dog, and we discover
Speaker 5: it by doing inventions, and that was the dog participating.
Speaker 1: I hope the dog was right. These are such great,
Speaker 1: thoughtful answers. Not surprised, of course, but impressed.
Speaker 3: When I started researching a city on Mars, one of
Speaker 3: the things that I loved was that people would say, Oh,
Speaker 3: obviously X is the case, and then you'd go and
Speaker 3: talk to the next group and they'd be like, obviously,
Speaker 3: why is the case? I think the most common version
Speaker 3: for me was obviously we can't settle space right now.
Speaker 3: And then other people would be like, obviously we're ready
Speaker 3: to do it right now, and I'd be like, oh,
Speaker 3: my goodness, how can everybody be so sure? But anyway,
Speaker 3: so we've got a nice mix of answers.
Speaker 1: I love those moments because then you get to dig
Speaker 1: into the assumptions that are leading you there and open
Speaker 1: people's mind. So hold on a second. That's an assumption
Speaker 1: that's not something you know, and maybe it feels natural
Speaker 1: to you, it feels intuitive, But do you have data?
Speaker 1: Do you have one of the reasons for holding those assumptions.
Speaker 1: Those are the moments when your mind expands, right when
Speaker 1: you're like, oh, wait, maybe eyeballs are a good snack
Speaker 1: after all, you know.
Speaker 3: I feel like at the top of my list of
Speaker 3: people that I want to correct me is you, because
Speaker 3: when you're like, you know, when what you mean is well,
Speaker 3: that sounds kind of wrong. Instead it sounds like an
Speaker 3: amazing philosophical insight, and I'm like, oh, that's such a
Speaker 3: cool way to think about and then afterwards you're like,
Speaker 3: wait a minute, Daniel told me I'm wrong.
Speaker 1: You know. That's my process with students and actually with
Speaker 1: podcast listeners. They often come to me with a question
Speaker 1: and the question doesn't really make sense or and it
Speaker 1: makes me realize they've absorbed some piece of information that's
Speaker 1: wrong and that's led them down this path. And so
Speaker 1: I feel like the job of a teacher is not
Speaker 1: to say you're wrong, here's the right answer, but to
Speaker 1: unravel their thought process to the moment they took the
Speaker 1: wrong path and show them the right way to go.
Speaker 3: Yeah, And that's one of the reasons I like working
Speaker 3: with you so much, because I feel like you're an
Speaker 3: easy person to throw ideas out at because you're not
Speaker 3: going to be told, well, that was stupid. So anyway,
Speaker 3: all right, our listeners are amazing. Let's jump into what
Speaker 3: does this question even mean? What assumptions are in that question?
Speaker 1: I think a lot of people might hear this question,
Speaker 1: especially a lot of people in physics, and say, well,
Speaker 1: of course, the laws of physics are something we're discovering,
Speaker 1: because there's something real happening out there in the universe,
Speaker 1: and we have this process of science for slowly deducing
Speaker 1: the truth, and you know, we use mathematics to express
Speaker 1: it and it just works so well, and so I
Speaker 1: think it's the natural point of view. The place people
Speaker 1: often start is that, Okay, physics is something we're figuring
Speaker 1: out about the universe, and lots of physicists feel that.
Speaker 1: I remember talking to string theorist Thomas van Reet and
Speaker 1: he was like, yes, aliens will be doing string theory.
Speaker 1: I don't even doubt it. His confidence was amazing. Yep,
Speaker 1: I love that, and there's reasons for that. It's not
Speaker 1: an unreasonable point of view, but it's also not the
Speaker 1: only point of view. And you know, this question is
Speaker 1: similar to another, maybe more widely discussed question in philosophy
Speaker 1: and in popular discussion, which is about mathematics. Right, is
Speaker 1: mathematics invented or discovered? And here mathematics is the language
Speaker 1: of science, and so it's natural to ask, like, well,
Speaker 1: is mathematics like our mental shorthand for the way the
Speaker 1: universe works? Or is it some part of the universe?
Speaker 1: Did the concept of seven exist before there are humans,
Speaker 1: you know? Or is it something that we came up
Speaker 1: with to help explain the universe around us. You know,
Speaker 1: I think a way to sum up the question essentially,
Speaker 1: is is physics the map or is it the territory?
Speaker 1: Are we describing something that's happening out there in the
Speaker 1: universe or are we revealing the actual truth?
Speaker 2: So could you give me an example?
Speaker 3: Like, all right, so say you've got a theory and
Speaker 3: you make some observations and the observations matches what you
Speaker 3: would expect from the theory, Bing bamboom, You've got it right,
Speaker 3: And so like, why is that not sufficient?
Speaker 1: Yeah, that's a great question. If you have a bunch
Speaker 1: of data and you have a theory that describes that,
Speaker 1: there's always another theory that also fits that data, right,
Speaker 1: because you don't have infinite data, and you could have
Speaker 1: two theories that deviate between the two data points. Or
Speaker 1: for example, I could just take our current theory and say,
Speaker 1: here's another theory that also describes the universe. It's exactly
Speaker 1: the same, but it predicts that in one hundred years
Speaker 1: electrons will lose their charge. I mean that theory perfectly
Speaker 1: describes all of our experiments. It's sort of ridiculous reason
Speaker 1: to believe in is obviously has this added twist to
Speaker 1: it that you don't need, and you can use outcomes
Speaker 1: razor to reject it. But it's just an example of
Speaker 1: how there are always more theories that do describe the data,
Speaker 1: and so you can't be guaranteed just by having a
Speaker 1: theory that matches your data that it's the only theory,
Speaker 1: or even that it's the true theory.
Speaker 3: Yeah, I mean, could there be like some intermediate between
Speaker 3: your theory and the observation that wasn't incorporated in some way,
Speaker 3: Like you think that X causes why, but actually there's
Speaker 3: a Z that's interacting there that wasn't in your theory
Speaker 3: at all, and that would change predictions in another environment
Speaker 3: or something.
Speaker 1: Exactly, because perhaps you only have data in a certain
Speaker 1: set of circumstances, right, and you haven't seen the wider picture.
Speaker 1: For example, for hundreds of years, we thought Newton was
Speaker 1: right about gravity, and his theory bore out every single
Speaker 1: test we did until we pushed the boundaries and we
Speaker 1: started looking at really high speed events and you know,
Speaker 1: the orbit of mercury and tiny little details. Only then
Speaker 1: was it revealed that Newton's theory wasn't as accurate as
Speaker 1: we thought, and in fact the whole story that it
Speaker 1: was telling, right and forces between them, that story is
Speaker 1: not the story of what's really happening in the universe.
Speaker 1: Now we have another story, Einstein's story of curvature and
Speaker 1: space time. Right, the two agree almost always in our experience,
Speaker 1: but they tell a very very different story about what's
Speaker 1: really happening behind the curtains. And that's philosophically sort of
Speaker 1: scary because it tells you that you could have a
Speaker 1: theory that describes almost everything you see in the universe,
Speaker 1: but it could be telling the wrong story about reality.
Speaker 1: And when the aliens show up and they're like, what,
Speaker 1: what are you guys talking about? That's nonsense. Here's what's
Speaker 1: really going on.
Speaker 3: Okay, But so let's imagine a world where and heaven forbid,
Speaker 3: this is the case where we never meet aliens, Like,
Speaker 3: I know, I'm so sorry, I'm so sorry. Would it
Speaker 3: still matter, Like, if we've got predictions and we can
Speaker 3: use those to make new technologies, does it matter if
Speaker 3: we actually are right or not, or if we've just
Speaker 3: figured out a way to understand the world that's helpful.
Speaker 1: Yeah, great question. I think it depends on what's important
Speaker 1: to you. If what's important to you is, let's build
Speaker 1: cool technology and you know, self driving toothbrushes and whatever,
Speaker 1: then it doesn't really matter, right. But if your goal
Speaker 1: is to reveal something true about the universe to understand,
Speaker 1: and I think in the end that's what physics is about.
Speaker 1: Fundamental physics is a desire to unravel the nature of
Speaker 1: the universe, not just to build cool gizmos. Then it's
Speaker 1: fundamentally frustrating to think that we're not doing that, that
Speaker 1: we're just telling ourselves a story that works, that we're
Speaker 1: not actually hearing from the oracle and revealing the truth
Speaker 1: of the universe, that we're stuck in Plato's cave, essentially
Speaker 1: just looking at shadows on the wall. Yeah, I think
Speaker 1: that would be fundamentally frustrating.
Speaker 2: Absolutely, Yeah, I'll give you that.
Speaker 1: But you ask a great question because aliens haven't arrived yet,
Speaker 1: and so you might ask, like, well, what progress can
Speaker 1: we make anyway on this question before the aliens show up?
Speaker 1: Do we have to just sit here and wait for
Speaker 1: the aliens to arrive and say like yes or no,
Speaker 1: or see how it works? And so that was sort
Speaker 1: of the struggle I faced trying to write this book,
Speaker 1: it's like, well, how do we make any progress before
Speaker 1: the aliens show up? And it turns out you can, right,
Speaker 1: you can look at the structure of human science and
Speaker 1: you can ask like, well, are there places where the
Speaker 1: choices we've made are arbitrary? Or are there things that
Speaker 1: could only have happened this way and in this area.
Speaker 1: I have to give a lot of credit to like biologists,
Speaker 1: because biologists have already done this work. Congratulations, Kelly. You know,
Speaker 1: like biologists have thought about is life on Earth the
Speaker 1: only way it could be? We only have this one
Speaker 1: example of life on Earth, but they've tried their best
Speaker 1: to push beyond the box. For example, they see that
Speaker 1: all life on Earth has carbon as its backbone, but
Speaker 1: that doesn't mean you can assume that all life in
Speaker 1: the universe is carbon based. They imagine ways it could
Speaker 1: have gone differently. Maybe it's silicon in there, right, or
Speaker 1: all life has water in it, but maybe it could
Speaker 1: have had ammonia. So there's been a lot of this
Speaker 1: like push beyond our one example thinking in biology, and
Speaker 1: I wanted to do the same thing for physics, to
Speaker 1: examine the places in physics where oh, maybe this could
Speaker 1: be different or no, this absolutely has to be this way,
Speaker 1: there's no other choice as a way to try to
Speaker 1: figure out before the aliens show up, what truths were
Speaker 1: revealing and what are just stories we're telling ourselves.
Speaker 3: All right, let's take a break and when we get back,
Speaker 3: Daniel will tell us where we should start looking.
Speaker 2: All right, and we're back. So Daniel was.
Speaker 3: Telling us about how biologists are leading the way and
Speaker 3: like probably everything, and physicists are trying to catch up,
Speaker 3: and so what kind of work are they doing to
Speaker 3: try to catch up?
Speaker 1: Daniel, Well, it's an impossible task as cool and as
Speaker 1: good looking and as suave, and it's socially well adjusted
Speaker 1: as biologists athletic, but you know we Oh sorry, I
Speaker 1: thought you were joking. I'm going to take that totally seriously.
Speaker 1: I'll have you know that we have a physics soccer
Speaker 1: game here every year and the faculty usually win.
Speaker 2: Oh nice way to go.
Speaker 1: Yeah, So, following in the footsteps of the wise biologists,
Speaker 1: we can ask like, well, where are the places where
Speaker 1: physics could be making assumptions? What are the arguments that
Speaker 1: suggest physics has to be universal? And what are the
Speaker 1: arguments against that? And I think one of the most
Speaker 1: powerful arguments is that physics seems to apply everywhere. Right,
Speaker 1: we have this universality of physics, which really goes back
Speaker 1: to Newton, Newton looking at the apple or thinking about
Speaker 1: gravity and imagining, oh, maybe gravity doesn't just apply here
Speaker 1: on Earth, it applies also in the heavens. Right. He
Speaker 1: takes the physics that we deduce these tiny little apes
Speaker 1: on this little rock and applies it to the cosmos.
Speaker 1: And that's that's such a huge leap, right. It's incredible
Speaker 1: to think that the laws of physics we're writing down
Speaker 1: on pieces of paper, never having left this planet, really
Speaker 1: with a very small number of exceptions very nearby, could
Speaker 1: apply to things happening across the universe. And that might
Speaker 1: sound like Hubris, right, but it's also totally backed by data,
Speaker 1: Like we can look at distant galaxies in the telescope
Speaker 1: and we can see they are following basically the same
Speaker 1: rules of physics. We can understand what's happening there back
Speaker 1: in time and far away.
Speaker 3: Ye's funny Hubvers was exactly the word I that was
Speaker 3: rolling around in my brain the way to free Kelly's critique.
Speaker 1: And there's a really fantastic example of this which is
Speaker 1: very recent maybe people heard about this validation of Hawking's
Speaker 1: area theorem. Hawking was thinking about black holes and how
Speaker 1: they come together, and he applied the laws of thermodynamics. Thermodynamics,
Speaker 1: of course, having its origins in like eighteen century dudes
Speaker 1: in essentially steampunk outfits playing with gas in valves and engines, right,
Speaker 1: I'm in yeah, and they were thinking about heat and
Speaker 1: energy transfer and they figured out some cool stuff and
Speaker 1: Hawkings said, oh, let's apply this to black holes. And
Speaker 1: he came up with this theorem about how black holes merge,
Speaker 1: and because black holes have entropy. When black holes come together,
Speaker 1: he said, well, the merger of the two black holes
Speaker 1: have to result in a black hole that's bigger than
Speaker 1: the sum of the two initial areas, because the area
Speaker 1: of the black hole is connected to its entropy. And
Speaker 1: we just saw this happen with this direct validation of
Speaker 1: Hawking's area theorem. So you have this direct line from
Speaker 1: like dudes with gas flasks to like black holes a
Speaker 1: billion light years away. It really is incredible that the
Speaker 1: laws of physics we figure out here seem to apply everywhere.
Speaker 1: And so we have this, you know, Newton's leap to
Speaker 1: the cosmos and then Carl Sagan and folks make another leap.
Speaker 1: Carl Sagan, when asked, do you think that aliens do
Speaker 1: physics and math the same way we do? He said,
Speaker 1: quote yes, And the reason I think that's likely is
Speaker 1: that they live in the same universe as we, so
Speaker 1: they must deal with the same laws of physics and
Speaker 1: chemistry and astronomy as we. So this is Carl Sagan, who,
Speaker 1: of course, you know, I hesitate to disagree with on
Speaker 1: anything because smart dude, fantastic science communicator, right the best.
Speaker 1: Maybe I want to, but I want to underline that
Speaker 1: he's making a second leap there, even bigger than Newton's leap,
Speaker 1: to apply the laws of physics across the heavens. He's
Speaker 1: saying that because the laws of physics that we have
Speaker 1: to do seem to work everywhere, they must be discovered
Speaker 1: the same way everywhere, or thought of the same way everywhere.
Speaker 1: And that's really a step beyond right. I want to
Speaker 1: separate those two for people, because I think a lot
Speaker 1: of people conflate those two arguments that just because the
Speaker 1: laws of physics apply everywhere, our description of the laws
Speaker 1: of physics apply everywhere doesn't mean it's the only way
Speaker 1: to describe them.
Speaker 3: So would there ever be a way that you could
Speaker 3: convince yourself we have found the explanation or is it
Speaker 3: just like a continuous process of testing your theories over
Speaker 3: and over and over and over again and being willing
Speaker 3: to get rid of them if they're wrong, but never
Speaker 3: knowing one hundred percent for sure if they're totally right
Speaker 3: until the aliens come.
Speaker 1: I don't think you can know one hundred percent for
Speaker 1: sure if they're right, even after the aliens come. I mean,
Speaker 1: say the aliens show up and you know, they do
Speaker 1: physics the same way we have, and they follow the
Speaker 1: same path, and they figured out the answers, and they're
Speaker 1: just like, you know, the simplest possible scenario, there are
Speaker 1: a thousand years ahead of us. That doesn't mean that
Speaker 1: it's the only way to do it right. Even if
Speaker 1: five different groups of aliens show up and they're all
Speaker 1: doing quantum field theory, that doesn't mean that it's the
Speaker 1: only way. Maybe we're all affected by having the same
Speaker 1: evolutionary history or the same conditions or something. There could
Speaker 1: always be another way to think about it that we
Speaker 1: don't know, And so even having the aliens show up,
Speaker 1: I don't think is conclusive. I think one way to
Speaker 1: approach this is to think about how close the map
Speaker 1: matches the territory. Right, So this is the question of accuracy.
Speaker 1: And another argument people feel very strongly about is that
Speaker 1: our human physics must be true, must be real, because
Speaker 1: it works so darn well. Right. It's not just like
Speaker 1: some fuzzied description of the territory. Right, it's like, wow,
Speaker 1: bang on. And you know, we've talked on this podcast
Speaker 1: a lot of times about the incredible power of the
Speaker 1: standard model of particle physics. But you know, just to
Speaker 1: highlight it, like we can predict how particles interact and
Speaker 1: sit down and do pages and pages and pages of
Speaker 1: calculations and predict some measurement experimentalists will try to do
Speaker 1: to like ten decimal places. And then the experimentalists go
Speaker 1: out and they make these measurements, and it's like, this
Speaker 1: is amazing science on both sides. Like the theoretical calculation
Speaker 1: takes so much work and careful thought. The experiment to
Speaker 1: measure something so precisely is really difficult, requires very different skills.
Speaker 1: But the two numbers agree. And when you have a
Speaker 1: theory that predicts something to ten decimal places, oh, you're
Speaker 1: tempted to make that leap and to say, yeah, this
Speaker 1: isn't a description. This is a revelation. You know, this
Speaker 1: is like we have found the source code of the universe.
Speaker 1: And I remember thinking that as like a junior in
Speaker 1: quantmics at Rice, hearing about these experiments and seeing them
Speaker 1: compared to the theory and feeling like, there's no way
Speaker 1: this is just a description. We have really pulled back
Speaker 1: a veil on nature.
Speaker 3: Yeah, and that's a very inspiring idea.
Speaker 2: I love that.
Speaker 3: But then you look and you're like, oh, wait a minute,
Speaker 3: but we don't know how to reconcile quantum mechanics and
Speaker 3: all this other with all the other stuff, and so
Speaker 3: like you know, I m hmm, oh, I want to say.
Speaker 1: There you want to just generally go hmm, have you
Speaker 1: guys really figured it out?
Speaker 4: Well?
Speaker 3: I think maybe you all have figured a lot of
Speaker 3: things out, and truth be told, I'm very impressed by
Speaker 3: what you all have figured out. But you know, so
Speaker 3: you can look at all the things you have figured out,
Speaker 3: but there's still things that don't fit together the way
Speaker 3: that you would expect them to, which could mean that
Speaker 3: there's some other theory out there that would explain all
Speaker 3: of that stuff that hasn't been found yet, which we
Speaker 3: were talking to Ethan Siegel about the other day.
Speaker 1: I think, yeah, and that's the incredible puzzle of physics
Speaker 1: that quantum mechanics is super duper accurate in scenarios where
Speaker 1: you can ignore gravity particle collisions or interactions, right because
Speaker 1: gravity is so weak at the particle level. And also
Speaker 1: general relativity, a classical theory that ignores quantum mechanics, is
Speaker 1: super duper accurate in scenarios where you ignore quantm mechanics,
Speaker 1: so like black hole mergers and gravitational waves and the
Speaker 1: orbit of mercury, and you know, ring down of binary
Speaker 1: pulsars and frame dragging as measured in space. With these
Speaker 1: super duper precise balls that spin in gyroscopes and satellites,
Speaker 1: it's amazing how accurate general relativity is also, so you
Speaker 1: can make the same argument for general relativity, So like, wow,
Speaker 1: this has got to be reality, right, because it's so
Speaker 1: correct that every test we've ever done of general relativity
Speaker 1: has been bang on completely accurate. And it leaves you
Speaker 1: with the impression like wow, this is also the truth.
Speaker 1: But you make the point like you can't have two truths,
Speaker 1: especially if they disagree with each other. And these two
Speaker 1: don't agree. They don't agree not only on what's happening
Speaker 1: out there in the universe, like what's the story, you know,
Speaker 1: what's real, what's really running the machinery, They also don't
Speaker 1: agree about what is going to happen. They make conflicting
Speaker 1: predictions about what's inside a black hole, or how the
Speaker 1: universe began, or how it's all going to end in
Speaker 1: frustratingly places we can't test, we can't do experiments to
Speaker 1: reconcile yet. But you're right, and that points to a
Speaker 1: problem with this argument. Right, we have these very precise theories,
Speaker 1: but all of these theories are what we call effective.
Speaker 1: None of them, we think are actually describing the real
Speaker 1: truth of the universe. We think that all of our
Speaker 1: theories are describing this process we call emergence. If you
Speaker 1: think that there's a real truth out there, that microscopically
Speaker 1: the universe has something happening, and that our experience somehow
Speaker 1: bubbles out of that, right, well, this is incredible step there,
Speaker 1: this amazing feature of the universe that we don't have
Speaker 1: to know how the universe works at the microscopic level.
Speaker 1: It's fundamental base layer of reality in order to start
Speaker 1: doing science at the macroscopic level, because this magic happens
Speaker 1: where when you zoom out from the microscopic to the macroscopic,
Speaker 1: the rules are different and somehow simple, right, Like the universe.
Speaker 1: Imagine it's filled with these tiny buzzying strings or flings
Speaker 1: or whatever sprayings you know, is at the base layer
Speaker 1: of reality, And imagine you have no idea how that works. Right. Still,
Speaker 1: somehow you can zoom out and you can describe how
Speaker 1: a baseball flies across your backyard with simple mathematics. Why
Speaker 1: is that possible? Right? Why isn't it all just chaos
Speaker 1: from the bottom up the way Like we can't describe
Speaker 1: hurricanes using simple mathematics because it's a bunch of rain
Speaker 1: drops and doing all sorts of complicated things. Why doesn't
Speaker 1: the same thing hold for zooming out from the fundamental
Speaker 1: layer of reality? We don't know.
Speaker 3: Is it just too many moving pieces? Like you could
Speaker 3: maybe predict what you know, two rain drops are gonna do,
Speaker 3: but not a whole hurricane. And you can predict throw
Speaker 3: a ball because that's there's a limited number of things
Speaker 3: acting on that. But the more complicated it gets the
Speaker 3: more we're.
Speaker 1: Like, oh, yeah, exactly. Sometimes simplicity emerges, right, and sometimes
Speaker 1: it doesn't. And when it doesn't, the reason is chaos.
Speaker 1: Like you have two rain drops, you can maybe describe it.
Speaker 1: You have ten to the twenty rain jobs. There's too
Speaker 1: many interactions and the outcome is very sensitive to how
Speaker 1: those rain jobs started in the direction they were going,
Speaker 1: and no simplicity emerges. It just gets more and more
Speaker 1: complicated as you add rain drops. But sometimes simplicity does emerge.
Speaker 1: You have ten to the twenty six particles moving across
Speaker 1: your backyard. They pull together and they follow a simple parabola.
Speaker 1: Hurricanes don't follow simple parabolas. And so because we don't
Speaker 1: understand why it ever happens right and why it doesn't
Speaker 1: always happen, that tells us that we're not sure if
Speaker 1: it's a part of the universe. Like is the fact
Speaker 1: that we can attack the questions of the universe and
Speaker 1: make some progress at some levels without knowing what's going
Speaker 1: on underneath. That we can make chicken soup without knowing
Speaker 1: quantum gravity? Is that because that's just how the universe is.
Speaker 1: Simplicity emerges and we'll figure that out. Why that is
Speaker 1: at some point or is it part of our minds?
Speaker 1: Is it the way that we understand and filter the universe?
Speaker 1: Is it some selection we're making that we're like, we're
Speaker 1: going to choose this thing to focus on, ask questions
Speaker 1: and do signs, and we're going to choose that thing.
Speaker 1: Is it an interplay between our brains and the universe
Speaker 1: or is it only part of the universe. And that's
Speaker 1: the kind of question we could answer if we had
Speaker 1: alien brains, right, which work differently, and maybe they saw
Speaker 1: different things emerging, or maybe they saw the same. We
Speaker 1: just don't know where the line is between the human
Speaker 1: and the universe.
Speaker 2: Alternative idea.
Speaker 3: We put a ton of money into trying to make
Speaker 3: bats which echo locate, and bees which see in more colors.
Speaker 3: We try to make all of them have advanced intelligence
Speaker 3: and then see what they come up with, because now
Speaker 3: we'll have different ways of looking at the world, and
Speaker 3: we've discovered that biology needs more money for physics sake.
Speaker 1: Oh I see right, yes, Okay. In the end, it's
Speaker 1: all just a scheme. Yeah, nice for big biology.
Speaker 2: I'm schemey Okay.
Speaker 3: So is the idea here then that like if we
Speaker 3: could dig down and understand everything at exactly the base level,
Speaker 3: and then we could scale up and understand the hurricane.
Speaker 3: Would that make us feel like we had discovered something
Speaker 3: or would we still just be inventing because we just
Speaker 3: managed to describe what happened mm hmmm instead of necessarily
Speaker 3: knowing why.
Speaker 1: Yeah, great question, And that's the temptation. And you know,
Speaker 1: I'm a particle physicist. That's my goal. It's like, I
Speaker 1: want to drill all the way down to the base
Speaker 1: layer of reality and find out what are the bits there?
Speaker 1: Because philosophically, that feels like that's a moment of possible revelation.
Speaker 1: You forced the universe to tell you, Okay, I'm naked.
Speaker 1: Now here are all my basic components. Now you've seen
Speaker 1: the reality of how things work everything else, how things
Speaker 1: come together and make baseballs and marching bands and whatever.
Speaker 1: You know, that's more complex science, that's basically chemistry. But
Speaker 1: you know, the fundamental physics is about the fundamental things
Speaker 1: in the universe. So yeah, if we drilled all the
Speaker 1: way down to those, wouldn't we have those in common
Speaker 1: with aliens? Could we avoid all these questions of like
Speaker 1: what's emergent and why? Well, the problem with that is,
Speaker 1: we don't know if there is a fundamental layer. You know,
Speaker 1: I think about our theories is sort of like a tower.
Speaker 1: We have this tower of effective theories at different scales,
Speaker 1: like zoom all the way out. We have like theories
Speaker 1: about how galaxies work. Zoom a little bit in. You
Speaker 1: have theories about how planets form. Zoom a little bit
Speaker 1: more in. You have like classical physics of the every
Speaker 1: day Zoom even more. You have chemistry, Zoom even more.
Speaker 1: You have physics, Zoom even more, you have particle physics.
Speaker 1: You could keep zooming. And at every level we have
Speaker 1: a theory. Do we know that there is a foundational truth,
Speaker 1: like a base layer to reality. We haven't found it, right, We.
Speaker 3: Just got to get to the plank scale.
Speaker 1: Well, we definitely got to keep going. But the problem is,
Speaker 1: number one, we have no guarantee that there is a
Speaker 1: fundamental layer. And I hear this all the time. Plank
Speaker 1: scale is the pixel of reality. And Elon Musk likes
Speaker 1: to say, and it's sort of out there in the
Speaker 1: popular science world that we somehow know that the plank
Speaker 1: scale is the layer, the finest grain we have of reality.
Speaker 1: And that's just fundamentally a misunderstanding. The Plank scale is
Speaker 1: the point where we can no longer ignore gravity when
Speaker 1: we do our quantum mechanical calculations because things are so
Speaker 1: hot and so dense, and we can no longer ignore
Speaker 1: quantum mechanics when we do our gravity calculations because things
Speaker 1: are so small and the particles are now relevant. And
Speaker 1: so it's just the point beyond which we can no
Speaker 1: longer calculate. It's sort of like an intellectual horizon, right.
Speaker 1: We don't know anything about what's below the Plank scale.
Speaker 1: I remember, the plank scale is not even like a
Speaker 1: solid estimate of these things. It's just like, well, let's
Speaker 1: take a bunch of constants and mush them together until
Speaker 1: we get a distance. That's not like a reliable way
Speaker 1: to estimate things. It's what you do when you have
Speaker 1: no idea how to answer a question on a test.
Speaker 1: I'm just going to guess the units and see what
Speaker 1: numbers I can push together to get the right units.
Speaker 1: Maybe this is close. I hope it's within a factor
Speaker 1: of one hundred or one thousand. So the playing scale
Speaker 1: is no guarantee that the universe has a fundamental layer.
Speaker 1: And if you talk to philosophers, they think it's just
Speaker 1: as likely that the universe as what they call gunky right,
Speaker 1: that everything is made of something smaller, nothing is made
Speaker 1: of itself. And immediately you're like, what come on, how
Speaker 1: could that possibly be? But actually, if you think about it,
Speaker 1: it's the more natural explanation. Everything we've ever seen has
Speaker 1: been made of something else, So why would we expect
Speaker 1: there to be something which is just made of itself.
Speaker 1: It feels sort of like, you know, the cause that
Speaker 1: needs no cause. You know, it's a bizarre philosophical construct,
Speaker 1: and we assume it's natural even though we've never seen
Speaker 1: it in the universe. So this is the kind of
Speaker 1: stuff where you really got to ask yourself, why do
Speaker 1: I accept this explanation and not that other explanation when
Speaker 1: I have no evidence and not even really great arguments
Speaker 1: for it.
Speaker 3: So you're saying that we might be just digging down
Speaker 3: and down and down and down ad infinitum.
Speaker 1: Yeah, it could be that it goes on forever, right,
Speaker 1: that it's just smaller and smaller and smaller down infinitely, right,
Speaker 1: an infinite tower of effective theories, an infinite tower of
Speaker 1: emergent phenomena. And so we can't shortcut this question by saying,
Speaker 1: we're just going to zoom down to the fundamentals and
Speaker 1: talk to the aliens about the sprawings or the springs
Speaker 1: or the shmings or whatever is down there at the
Speaker 1: fundamental layer, because we don't know that there is a
Speaker 1: fundamental layer.
Speaker 3: Do you think they'll stop giving out Nobel Prizes eventually
Speaker 3: if it turns out there's just like infinite fundamental layers
Speaker 3: and they're like, you know, Kelly found the twentieth one,
Speaker 3: Daniel found the twenty fifth.
Speaker 2: Hooray oh.
Speaker 1: In this scenario, you're a particle physicist who's discovered some
Speaker 1: fundamental layer of reality. Love that.
Speaker 2: Welcome a book, ellogist, Man, I can do anything. Thanks.
Speaker 1: After you win the Olympics, right, and I'm gonna hang
Speaker 1: this no next to my Olympic gold medal. Wow? Wait?
Speaker 1: Has there ever been anybody who won an Olympic medal
Speaker 1: and a Nobel Prize?
Speaker 3: Hmm oh, Philip Noel Baker is the only person who
Speaker 3: has won both an Olympic medal and a Nobel Prize.
Speaker 3: Amazing it was for a race in the nineteen twenty
Speaker 3: Summer Olympics. I mean things were easier then.
Speaker 1: That's an incredible achievement.
Speaker 2: Congrats, dude, I think he's passed away.
Speaker 1: Yeah, so it could be the particle physics is just
Speaker 1: a big grift for infinite Nobel prizes. Yes, that's the
Speaker 1: answer to your question. Oh yes, you forced me to
Speaker 1: reveal that on air.
Speaker 2: Thank you, amazing, amazing.
Speaker 3: Well, yeah, good time, My work here is done, all
Speaker 3: right on the next episode.
Speaker 1: No, So, now, imagine, right, we have this tower of
Speaker 1: effective theories that we use to describe science. We have chemistry,
Speaker 1: we have physics, we have particle physics, we have subatomic
Speaker 1: particle physics. And the question then is like, well, if
Speaker 1: they there's no firmament in which to ground these things,
Speaker 1: and we don't know why these things seem to emerge
Speaker 1: to allow us to explain them, why they're not just
Speaker 1: like totally intractable, then do we know if aliens would
Speaker 1: or wouldn't find the same tower of effective theories? Like,
Speaker 1: you know, the skeptic in you might say, well, look,
Speaker 1: you know, planets are obviously a thing. Aliens are going
Speaker 1: to think about planets, you know, orbiting stars. Like, let's
Speaker 1: not get ahead of ourselves and get too deep in
Speaker 1: the philosophy that we imagine that like aliens don't observe
Speaker 1: planets and come up with Kepler's laws, right, That's so,
Speaker 1: I think that's like an intuitive argument people might make
Speaker 1: to feel like aliens are going to see the same
Speaker 1: stuff as we.
Speaker 3: They're probably going to call it Zorblacks's laws or something,
Speaker 3: you know, yeah, exactly.
Speaker 1: And that might be right. And I don't want to
Speaker 1: say that that's impossible, but I do want to open
Speaker 1: your mind maybe a little bit, to the possibility that
Speaker 1: they wouldn't see planets. Think about why we think about
Speaker 1: planets and does it actually make sense to think about planets,
Speaker 1: because in reality, the Solar system is a big spectrum
Speaker 1: of stuff. You know, you have the Sun and then
Speaker 1: you've got a bunch of other little blobs, and those
Speaker 1: blobs go all the way from Jupiter down to dust
Speaker 1: specs and humans we like to categorize things, right, We
Speaker 1: like to say this is A and this is B.
Speaker 1: And historically we saw a few different kinds of things,
Speaker 1: and so we started making boxes. But also we've seen
Speaker 1: over time that those boxes don't really make sense. That
Speaker 1: our categories of stuff are sort of arbitrary dotted lines
Speaker 1: that we draw around things and not just randomly we
Speaker 1: draw those arbitrary dotted lines in a way to make
Speaker 1: ourselves more important. This whole concept of planets that we
Speaker 1: argue with Phil Metzger about it recently on the podcast.
Speaker 1: Does it even make sense to have this category? It's
Speaker 1: obvious to me because this category has become so baroque.
Speaker 1: You know, they have to add so many qualifiers. It
Speaker 1: has to have cleared its path that has to be
Speaker 1: gravitationally round. They're reverse engineering this category because we like it.
Speaker 1: We want there to be a special category of things
Speaker 1: that seem important and that are relevant to us. But
Speaker 1: if you're going to take like a hard objective scientific
Speaker 1: eye to the Solar System, you might never come up
Speaker 1: with this special category of planets. You might just think
Speaker 1: about the whole spectrum of things and not focus on
Speaker 1: Earth like things at all.
Speaker 3: So would you argue that definitions are I mean, they're
Speaker 3: certainly invented. Yeah, is a definition ever discovering the nature
Speaker 3: of the universe? I guess it's always just our way
Speaker 3: of grappling with stuff.
Speaker 1: I think definitions are helpful, but categories are often very
Speaker 1: arbitrary and lead you down the wrong path and make
Speaker 1: you think something is special or something is different when
Speaker 1: in reality there's a spectrum. You know, think about gender,
Speaker 1: think about like you know, the platypus, right, which is
Speaker 1: like what And these categories they're helpful for organizing your thoughts.
Speaker 1: But you got to remember that there are things we
Speaker 1: impose on the universe. They're not always things that emerge
Speaker 1: naturally from the universe. And that's the point I want
Speaker 1: to make, is that even things that we feel like
Speaker 1: we are just observing have a lot of our cultural
Speaker 1: bio in them. I mean, think about the way we
Speaker 1: represent the Solar System when we draw it out right,
Speaker 1: like it's not representative at all. We take the planets
Speaker 1: and we like magnify them by huge numbers to make
Speaker 1: them relevant, when in reality they're pretty irrelevant. The Solar
Speaker 1: System is basically the Sun plus a few drops of gas, right.
Speaker 1: So it's obvious once you drill into it that there's
Speaker 1: a lot of humanity in our choices of what to
Speaker 1: study and think about in the universe. And so it
Speaker 1: might be that aliens have made different choices that they're
Speaker 1: like they grew up in the atmosphere of a star
Speaker 1: and they're like planet Schmanitz, who cares? Or maybe they
Speaker 1: evolved in a subsurface ocean on a moon, and so
Speaker 1: to them, like who cares at all about planets? Maybe
Speaker 1: they think about things fundamentally differently.
Speaker 3: All right, let's take a break and when we get
Speaker 3: back we will answer the simple question of whether or
Speaker 3: not there is a truth at all. And we're back
Speaker 3: and we are about to answer, you know, the only
Speaker 3: question that really matters, which is is their truth at all?
Speaker 3: And the good news is Daniels thought a lot about
Speaker 3: this and now we're going to know.
Speaker 1: Right, Yes, we're just going to wrap up a millennia
Speaker 1: old philosophical conversation here on the pod today. So so
Speaker 1: far we've been talking as part of the larger question
Speaker 1: of like is physics discovered or invented? We've been asking
Speaker 1: like could you have several maps of the same territory?
Speaker 1: But it always in that sense assumes that there is
Speaker 1: a territory, that there is fundamentally something that's going on.
Speaker 1: I heard this sentiment in the listeners responses, right, well,
Speaker 1: maybe our description of the universe is human, but there's
Speaker 1: something going on. And so let's question that assumption, like,
Speaker 1: how do we know that there really is something going
Speaker 1: on out there in the universe one truth, whether or
Speaker 1: not we're just discovering it or describing it or approximating it. Right,
Speaker 1: how do we know that there really is something that's
Speaker 1: going on out there? And when I first started digging
Speaker 1: into this, I thought, well, of course there is, right,
Speaker 1: something is happening in the universe, and there has to
Speaker 1: be a reason why stuff happens, right, But not surprisingly,
Speaker 1: philosophers have responses to that, and they've thought about ways
Speaker 1: that might not be true because remember that all of
Speaker 1: our descriptions of the universe, they are approximate, right, because
Speaker 1: we can't do the really complicated calculations like we talked
Speaker 1: about earlier. We can describe a couple of rain drops,
Speaker 1: we can't describe the hurricane, or we can't describe like
Speaker 1: a bunch of hurricanes smashing into each other, or really
Speaker 1: complicated situations. There is always going to be something that
Speaker 1: we cannot describe. Because all of our laws are approximate, right,
Speaker 1: they only apply in certain situations. Like, for example, take
Speaker 1: fluid dynamics. Right, fluid dynamics works really well. It helps
Speaker 1: you think about how water flows down pipes. But we
Speaker 1: know number one, it's not a fundamental description of the universe.
Speaker 1: It's a description of an emergent phenomena. But number two,
Speaker 1: it's only valid in certain situations. You freeze that water,
Speaker 1: you no longer gonna apply fluid dynamics. You turn it
Speaker 1: into steam, you're no longer gonna apply fluid dynamics. In
Speaker 1: that same way, everything we can do about the universe
Speaker 1: has boundaries where it's relevant, right, and you go beyond
Speaker 1: those boundaries, you can no longer use your fluid dynamics
Speaker 1: or your chemistry, even fundamental physics. Right. Quantum mechanics and
Speaker 1: gravity are only relevant down to the plank scale, and
Speaker 1: beyond that, who knows what the laws of physics are.
Speaker 1: So there's a school of philosophy that says, h how
Speaker 1: do we know there are laws of physics? Beyond those boundaries? Maybe,
Speaker 1: instead of imagining that we have this patchwork of theories
Speaker 1: that eventually we could stitch together to describe the truth,
Speaker 1: maybe between those patches there's nothing. So Nancy Cartwright wrote
Speaker 1: this book called How the Laws of Physics Lie, and
Speaker 1: we're like, wow, bold title, right, Yeah, And she imagines
Speaker 1: the universe where between these patches where things get complicated,
Speaker 1: that maybe what happens happens by Hap. That's her phrase,
Speaker 1: that there is no fundamental rule, And you know, every
Speaker 1: instinct in me, every fiber of my being, says no,
Speaker 1: that's crazy, right, the universe follows laws. But then I ask, well,
Speaker 1: how do I know that exactly? I only know that
Speaker 1: because it seems to work in simple situations where I
Speaker 1: can set up a simplified experiment and I can do
Speaker 1: a calculation to predict it. And that's really what experiments are.
Speaker 1: Ways you've like tricked the universe into only doing something
Speaker 1: simple enough that we can calculate it. That's the whole
Speaker 1: job of experimental physics is to concoct these artificial scenarios
Speaker 1: where things are simple enough for us to predict. Most
Speaker 1: of the stuff that happens in the universe, from you know,
Speaker 1: like tiny particles to hurricanes to even like the leaves
Speaker 1: swirling outside my office, we could never hope to calculate.
Speaker 1: So how do we know that it follows rules? If
Speaker 1: you're going to be a skeptic about it, you got
Speaker 1: to say, like, hmmm, I guess we actually don't know, right.
Speaker 1: It could be that when things get complicated, there aren't
Speaker 1: laws that are being followed, And I don't believe that,
Speaker 1: but I don't have a scientific reason to not believe it.
Speaker 3: My brain has trouble wrapping itself around how that could
Speaker 3: possibly be true. But that might be the limit of
Speaker 3: my imagination.
Speaker 1: Yeah, and I think even Nancy Cartwright probably doesn't like
Speaker 1: believe this in her soul. But it's a very valuable
Speaker 1: exercise to think, well, is it possible for the universe
Speaker 1: to be different from what we expect at some deep
Speaker 1: fundamental way, because historically we've seen that happen. Right, the
Speaker 1: universe turns out it violates lots of our intuition, you know,
Speaker 1: the way things operate near the speed of light or microscopically,
Speaker 1: the fact that cause and effect has a stochastic element
Speaker 1: to it. These things we would have been rejected out
Speaker 1: of hand right initially, like that's crazy, there's no way
Speaker 1: the universe works that way. And yet it does. And
Speaker 1: so we do need to be prepared to have our
Speaker 1: minds blown. And that's the whole joy of this exercise,
Speaker 1: is to imagine, like what if aliens show up and
Speaker 1: they tell us the universe is really fundamentally different from
Speaker 1: the way that we expect. That's why we want the
Speaker 1: aliens to show up to shock us to reveal an amazing,
Speaker 1: mind blowing truth. And yeah, it'd be kind of disappointing
Speaker 1: to discover that the laws of physics only apply in
Speaker 1: simplified situations. And beyond that there is this darkness right
Speaker 1: where the universe doesn't follow laws, but we don't know
Speaker 1: that it's not true.
Speaker 3: I feel like if the aliens came and they were like, nah,
Speaker 3: you guys are totally wrong, like I mean, it would
Speaker 3: be wouldn't it be decades before you could convince yourself
Speaker 3: that they were right?
Speaker 2: Instead?
Speaker 3: Would you like, if the alien said, Daniel, you're wrong,
Speaker 3: would you just be like, all right, I'm throwing away
Speaker 3: everything we know the alien said so, and I'm a
Speaker 3: super fan.
Speaker 1: Yeah, that's a really fun question. So in the book,
Speaker 1: I actually imagine a bunch of different alien contact scenarios,
Speaker 1: and one of them is that exact one. The aliens
Speaker 1: show up and have a competing theory of physics, and
Speaker 1: in that hypothetical example, I imagine that some humans are like, oh,
Speaker 1: you know, our theory never made sense to me. I
Speaker 1: really like this alien idea, and they go over to
Speaker 1: the alien camp and some aliens are like, oh, you
Speaker 1: know what, I really prefer the human way, and like
Speaker 1: people have different ways of thinking, the way that some
Speaker 1: people need to see something written out and other people
Speaker 1: need to hear it, or some people need to play
Speaker 1: with something. Right, there's different kinds of learners. So maybe
Speaker 1: some people will find the alien description of the universe
Speaker 1: more intuitive and easier to play with, and other people
Speaker 1: will feel the opposite. It'd be fascinating how that breaks out.
Speaker 2: Yeah, it would. I hope I'm alive to see it.
Speaker 1: Another objection people make to the idea that we could
Speaker 1: be getting physics all wrong, or that physics could have
Speaker 1: a lot of humanity into it is the idea that
Speaker 1: you raised at the beginning of the episode. You know what,
Speaker 1: if we have a bunch of data and it describes
Speaker 1: the universe, doesn't that tell us that our theory is right?
Speaker 1: And this is this question of uniqueness, right do we
Speaker 1: know that there has to be one explanation for the universe?
Speaker 1: And earlier we were giving the examples of having a
Speaker 1: superseded theory, like, well, maybe you have a theory and
Speaker 1: it works for now, but then later you get more data,
Speaker 1: so you've got toss out that theory for a new one.
Speaker 1: That's cool. And that's almost certainly what we're doing today,
Speaker 1: right that in the future we'll have a theory of
Speaker 1: quantum gravity that tells us a different story about what's
Speaker 1: happening in the universe and any of the stories we
Speaker 1: have now, So we'll toss out our whole explanation for
Speaker 1: what's really out there and come up with a new one. Cool.
Speaker 1: But what if we find the fundamental layer of reality.
Speaker 1: We discover it and we explain it, and we have
Speaker 1: a theory that works perfectly and incorporates dark energy and
Speaker 1: dark matter and the expansion and everything, and all of
Speaker 1: our questions are answered and it tells us this beautiful
Speaker 1: story about what's happening. Then aliens show up. Could they
Speaker 1: have a different theory that explains the same experiments? Could
Speaker 1: they have done the same experiments, made the same observations,
Speaker 1: but draw a different line through the same data points.
Speaker 1: The answer is, philosophically, yeah, maybe, because you'll never have
Speaker 1: infinite data, and even if you did, you could always
Speaker 1: still draw two different curves. Right. Just imagine, like plotting
Speaker 1: a bunch of points on a piece of paper, how
Speaker 1: many curves could you draw through those points? An infinite number? Right?
Speaker 1: Make the curve as complex as you like, you can
Speaker 1: draw an infinite number, and so we never really know
Speaker 1: if our explanation is the only one. And this is
Speaker 1: something philosophers are deeply debating, Like there's a bunch of
Speaker 1: philosophers who say, look, if you have another theory that
Speaker 1: explains the data equally, well, it's got to be equivalent,
Speaker 1: you know, it's got to be like the same theory
Speaker 1: dressed in different clothes. And they point to good examples,
Speaker 1: like we used to have a wave theory of quantum
Speaker 1: mechanics and a matrix theory of quantum mechanics, each derived
Speaker 1: by a different German guy, and those two guys disliked
Speaker 1: each other and called each other's theories crap. And then
Speaker 1: later John von Neuman brought them together and said, look, guys,
Speaker 1: these are actually the same theory. I can draw connections
Speaker 1: between them and prove it. Or we used to have
Speaker 1: a bunch of different string theories until at Witten show
Speaker 1: they're actually just extreme points of the same m theory, right.
Speaker 1: Or we have like Hamiltonian mechanics and Lagrange and mechanics,
Speaker 1: two different ways to think about complex physics that are
Speaker 1: fundamentally the same. So isn't it just like that, maybe
Speaker 1: the aliens have a different description, but you know, you
Speaker 1: can make connections. We don't know, right, We don't know
Speaker 1: if every theory has to be that way. And another
Speaker 1: group of philosophers say that there might be another explanation,
Speaker 1: that it's possible to have another theory of physics that
Speaker 1: doesn't map over, that is conceptually different to our theory,
Speaker 1: But we don't know, right, we don't have that theory.
Speaker 1: We would have a recipe for building this alternate theory.
Speaker 1: So it's just like a speculation. It's an argument we
Speaker 1: don't know how to defeat, which means it might be possible.
Speaker 3: Okay, So if we ended up discovering the theory of
Speaker 3: everything and we felt like we had it all figured out, Yeah,
Speaker 3: I was going to ask you if you would put
Speaker 3: up a giant billboard saying never mind.
Speaker 2: Aliens, we got it all figured out.
Speaker 3: But what you're saying is you'd be interested to see
Speaker 3: if they had a different way to describe everything. But
Speaker 3: some philosophers would say, well, that doesn't really matter because
Speaker 3: it's fundamentally going to be the same theory, even if
Speaker 3: it's wearing different clothes.
Speaker 1: There's no scenario in which I'm putting up a billboard
Speaker 1: saying aliens never mind, no scenario, but yeah, we have
Speaker 1: a theory of everything and they show up and they
Speaker 1: have a different theory of everything. Then that's fascinating, right,
Speaker 1: because even if it is fundamentally the same, you're still
Speaker 1: learning something mathematically or philosophically and it's fundamentally different. If
Speaker 1: you can't make a connection between the two, boom, that
Speaker 1: tells you something mind blowing about the universe. That you
Speaker 1: could have two different maps of the same territory that
Speaker 1: both work. Then, like, is there really a territory? What
Speaker 1: does that say about our sense that there is an objective,
Speaker 1: physical reality that's out there that doing things following some
Speaker 1: laws that we're figuring out, Like, maybe that's not the case.
Speaker 1: Maybe things are more complicated or weirder than we imagine.
Speaker 1: So I'm always in the camp of hoping for the weird,
Speaker 1: surprising outcome.
Speaker 3: Danielle, I really hope you get your aliens one day.
Speaker 1: I hope I do, and I hope that they don't
Speaker 1: nuke us from space before they tell us the answers
Speaker 1: to all of these questions.
Speaker 2: You are a weird one, daniel and.
Speaker 1: This is just a taste of all the concepts we
Speaker 1: describe in the book Do Aliens Speak Physics, where we
Speaker 1: do a really deep dive into these questions. It also
Speaker 1: includes a bunch of really fun cartoons for my friend
Speaker 1: Andy Warner, who helped me write the book, and little
Speaker 1: hypothetical case studies to examine concrete scenarios where aliens could
Speaker 1: show up and be weirdly different in ways you might
Speaker 1: not expect. So if you enjoy these questions and enjoy
Speaker 1: this conversation, there's lots more in the book, go check
Speaker 1: it out Do Aliens Speak Physics. You can get it
Speaker 1: at www dot Alienspeakphysics dot com.
Speaker 3: And I think if aliens do come to visit the US,
Speaker 3: this book is going to be the first thing they
Speaker 3: grab travel across the cosmos for this book totally makes
Speaker 3: sense worth doing.
Speaker 1: I hope they're not offended by our depictions.
Speaker 3: Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio.
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