Is dark energy a fudge factor?

Daniel and Kelly talk about whether physicists are trying to understand the expansion of the Universe, or pull the cosmic wool over everyone's eyes. Also, horse milk comes up. See omnystudio.com/listener https://omnystudio.com/listener for privacy information.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Daniel Whiteson?

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• 3:53Daniel Whiteson?

  What's going on with the universe? First, we thought it was static, a single galaxy floating in space forever. Then we learned it's actually expanding. Everything out there is running away from us. More recently, we figured out it's actually accelerating. What's happening? This is one of the biggest questions in modern physics, and the whole area of studies loosely called dark energy, which is also, confusingly, sometimes, the name used to refer to the leading hypothesis for what's happening. But do physicists know what they're doing here? Is it physics, or is it just a bit of wonky math they stick in to make their precious equations work out? We're gonna dive deep into all of that and hear my rants on the subject.

• 4:37Daniel Whiteson?

  Plus, we'll have the usual hilarious digressions, all on today's episode of Daniel and Kelly's extraordinarily dark universe.

• 4:58Kelly Weinersmith?

  Hello, I'm Kelly Weinersmith. I study parasites and space, and this is the second fudge factor episode we've done.

• 5:05Daniel Whiteson?

  Hi, I'm Daniel. I'm a particle physicist, and I love thinking about how aliens imagine the universe. And I suspect that there are alien physicists out there like me who don't like fudge.

• 5:15Kelly Weinersmith?

  Oh, wait, we've talked about why you don't like fudge before. So two things. First of all, when I saw the outline you sent me, I thought, oh, Daniel didn't realize he sent me the same outline twice. And then I was like, oh, wait, this is different. Where do you think the phrase fudge factor came from?

• 5:31Daniel Whiteson?

  Oh, that's a great question. I'm gonna speculate without a chance to research about the history of this word. I don't know. I mean, in general, like, to fudge something means to mess it up or to fake it, right? And I wonder if that came from somebody like me who doesn't like fudge? Or there's another sort of scatological implication of fudge?

• 5:51Kelly Weinersmith?

  Yep, that occurred to me. That occurred to me.

• 5:53Daniel Whiteson?

  And so maybe that's a connection, like, oh, you fudged it. I don't know. That's a great question. What do you think?

• 6:01Kelly Weinersmith?

  I have no idea. I also, you know, as a biologist, the scatological connection was made in my brain, but I didn't bother looking it up. I just thought, I'll, you know, I'll ask Daniel. Are you looking it up?

• 6:14Daniel Whiteson?

  I'm asking the robot. Let's see.

• 6:17Daniel Whiteson?

  So, based on my internet research, the Oxford Dictionary of Word Origins says that the term "fudge" expresses annoyance and is traced to the 18th century, originating from another word "fudge," which sort of meant to fit.

• 6:33Kelly Weinersmith?

  So then where did the word "fudge" as a delicious treat come from?

• 6:40Daniel Whiteson?

  And apparently, fudge, the not-so-delicious treat, is characterized as like an accident. And so somebody was trying to make something else, and they fudged it, and they made fudge.

• 6:50Kelly Weinersmith?

  Oh, interesting. We learned something new today.

• 6:54Daniel Whiteson?

  Yes, and we unnecessarily went for the scatological reference.

• 6:58Kelly Weinersmith?

  Well.

• 6:59Daniel Whiteson?

  On brand for us.

• 7:00Kelly Weinersmith?

  Exactly, yes, yes. Well, well, we've previously talked about how dark matter is not a fudge factor. Or would you still say dark matter is a fudge factor?

• 7:11Daniel Whiteson?

  Oh, my God. Did you listen to the episode, Kelly? The whole point of the episode was dark matter is not a fudge factor.

• 7:17Kelly Weinersmith?

  Okay.

• 7:17Daniel Whiteson?

  And so, I mean, let me give some context here. You know, there's a lot we know about the universe, and we do our best to communicate it, but there's also a lot of misinformation out there about what we know and how it works. And a lot of folks out there under the impression that dark matter specifically is just like a number we plop in the equations to make the math work because we're stuck on some dogma and will never give it up, even if we have to insert ridiculous fudge factors in it to get it to describe the universe, which is not a fair characterization of dark matter, and also avoids the very rich, fascinating field that has surfaced like 10 independent lines of evidence for this thing we call dark matter.

• 7:58Daniel Whiteson?

  So I was inspired to do an episode contrasting this, like, popular science misinformation with the reality of the research of dark matter.

• 8:07Kelly Weinersmith?

  I just like railing you up.

• 8:10Daniel Whiteson?

  Well, button pushed successfully. And in that episode, I made a contrast between dark matter, which is a thing, and we have a lot of evidence for it, and definitely not a fudge factor. And I used the cosmological constant, which we'll talk about in more detail today, as an evidence of something which kind of is a fudge factor. And a bunch of people wrote in, and they were like, wait, are you saying dark energy is a fudge factor? And so I thought, all right, we need to do an episode on is dark energy a fudge factor? Not as a repeat, not as a rehash, but as an even deeper dive into the subject of cosmic fudge factors.

• 8:44Kelly Weinersmith?

  Well, I love fudge, and I love learning about whether or not something is a fudge factor, so I'm sure we're going to have a lot of fun today.

• 8:51Daniel Whiteson?

  All right, I hope we don't fudge it up.

• 8:54Kelly Weinersmith?

  Oh, watch it, Daniel. Why, we don't want Matt to have to start dropping a bunch of bleeps into this episode.

• 9:01Daniel Whiteson?

  Fudge is my new favorite archaic term.

• 9:03Kelly Weinersmith?

  I.

• 9:03Daniel Whiteson?

  I'm gonna use it everywhere.

• 9:04Kelly Weinersmith?

  I'm going to work on incorporating it into my life as well. I'm a little worried about what might happen if I use it in front of my seventh grader and then she uses it at school and slips up a little bit. So, all right. Well, we did what we always do here at DKEU, and the first thing we do when we have an interesting question is we share it with the extraordinaries.

• 9:23Daniel Whiteson?

  That's right. Research step number one is ask our audience.

• 9:27Kelly Weinersmith?

  That's right. And so we asked our audience, is dark energy a fudge factor? And if you want to be on the list of people who get our questions that are our first step of research, write to us at [email protected], and you can get added to the list of folks who get our emails.

• 9:42Daniel Whiteson?

  So think about it for a moment before you hear these answers. Do you think dark energy is a fudge factor? Here's what folks had to say.

• 9:50Speaker 07

  It doesn't mean that it's not real, just we don't know what it is or how it is yet. Well, I still don't really know what dark energy is, so I don't know.

• 10:01Speaker 03

  It seems maybe, maybe it's more of a thing than dark matter. I don't know. I have no idea. I think yes, until we know what it is. So I'm also a barista in my other job, and dark energy definitely sounds like a fudgy sort of latte. I would totally drink that. I don't think so. Something is creating space. Yes, we don't know what it is. We don't even know if it's a constant, so. Dark energy is not a fudge factor. Yes, I think it is.

• 10:34Speaker 02

  Your honor, I refer you to the previous case of dark matter and whether it's a fudge or not, in which I responded, it isn't. So therefore, I must also respond that dark energy is not a fudge either. We don't know the underlying mechanism with like, why it happens. So I mean, to me, that seems a lot like dark energy. Like, it could be one forces behind there, or it could be three forces. I do not think it is a fudge factor, but I have no idea how to classify it.

• 11:02Kelly Weinersmith?

  Dark matter is not a fudge factor. I think dark energy might be. All right. So if I remember correctly, from the dark matter episode, there was a lot of like, oh, I don't, I don't know. I think people were a little bit less willing to call it a fudge factor. It looks like there's a little bit more willingness to lean into fudge factoriness when it comes to dark energy.

• 11:24Daniel Whiteson?

  Some people here standing up for dark energy, you know, an empty space has energy, et cetera. But yeah, definitely a lot more skepticism here. And maybe we'll circle back at the end of the episode and see if that was justified.

• 11:35Kelly Weinersmith?

  Yeah, well, I think it shows that they've been listening to what you've been saying. So all right, let's, we, you know, we talked a little bit about the etymology of the phrase fudge factor. But let's go ahead and dig into like, what does a scientist mean when they say fudge factor? What is the scientific definition of this term?

• 11:54Daniel Whiteson?

  Yeah, well, I think fudge factor is used in two ways. One, it's used as an insult or a smear, you know, to suggest you have a theory that's not really serious. Or you're making the theory work, even though it's not right, you've fudged it, you know? And I think that's the essential implication or accusation in this popular misinformation. To say that scientists have an idea and it doesn't really work. And it's not even very convincing because all they've done is tweak the numbers to make it work. Or they've added something to the equation, something mathematical. That's the other implication, that this is purely a math trick and not something physical, not something real, not something that reflects

• 12:38Daniel Whiteson?

  how the universe actually works. Because the equations, if you left them alone, would predict something else, and you had to add a fudge factor. You know, like if I had some mathematical equation that predicted, you know, Kelly's height, and it predicted three feet, and then we were like, well, that's wrong, and I'm just going to add a number to it. I've fudged it so that it gets the right answer. You'd say like, hey, your Kelly height prediction equation is garbage because it's got a big fudge factor. And it needs a fudge factor to work, and therefore it's not any good.

• 13:10Kelly Weinersmith?

  But would you learn something if like, you know, if you said, okay, I'm gonna predict that Kelly is three feet tall, and then I'm going to add a fudge factor, but over time, every time the fudge factor ended up being the same value? Would that like hint at the realness of the importance of that mathematical constant or something? Like, are fudge factors a way of like placeholding? There's something we don't understand, but if it's always the same value, then maybe we're on to something important?

• 13:36Daniel Whiteson?

  Maybe. I think that you have your finger on something useful, though, which is that science is iterative. And often we can have fudge factors on the first attempt. You know, sometimes a fudge factor isn't a way to lie to people and mislead and to try to pull the wool over your eyes and get you to believe our theory. It's just a way to say, we don't know how this works. Let's try something. And if it doesn't quite work the first time, we'll insert some factors, some fudge factors, which will then intend to come back and revisit and improve on. Like, as you say, if my prediction for Kelly's height is three feet too short, and for Zach's height is three feet too short, and for Katrina's height is three feet too short, I'm going to go back and look at my prediction, like, why am I systematically three feet too short?

• 14:20Daniel Whiteson?

  What is wrong with my theory? And then I'm going to come back with another theory that I hope is more accurate, right? And so in that sense, a fudge factor is not always bad. It just sometimes means you're in the early days, you know? Like, say, for example, you're walking through your backyard and you see like elephant footprints, right? And so you're like, okay, well, I'm gonna assume there's probably some elephants. I don't have direct evidence yet, but I have a theory that there are elephants walking through my backyard. If you come back later and you find like elephant poop and tusk marks and you smell elephants, you're like, okay, yeah, the theory's probably right. But if you don't, or if you come back and you see like cow poop and you smell horses and the evidence doesn't really come together, then, you know, you got to adapt your ideas.

• 15:02Daniel Whiteson?

  And so it's okay to have initial guesses that aren't totally solid. Even sometimes just numbers that you put in there that you don't yet know how they work until you later do figure out why they work. It just reflects that you're not done sometimes.

• 15:18Kelly Weinersmith?

  I find myself trying to figure out how many people there are on this planet that could sniff the difference between an elephant, a cow, and a horse. There must be someone who works at a zoo who can do that.

• 15:31Daniel Whiteson?

  I think I can do that. I've spent enough time around horses with my daughter that like, this is a very definite horsey smell, for sure.

• 15:39Kelly Weinersmith?

  But is it different than a cow poop smell? Because they're all eating grass. Okay.

• 15:45Daniel Whiteson?

  Well, I mean, you know how different animals all have cheeses that taste different, right? Like goat cheese tastes different from cow cheese. You ever notice how goats smell different from cows? And how goat smell is sort of related to the way goat cheese tastes?

• 15:59Kelly Weinersmith?

  I love it.

• 16:00Daniel Whiteson?

  Right? There's just like a goatiness.

• 16:02Kelly Weinersmith?

  Yeah. And the goat milk has a bit of a goatiness, too.

• 16:04Daniel Whiteson?

  Yes, exactly.

• 16:06Kelly Weinersmith?

  All right, point made.

• 16:10Daniel Whiteson?

  I've never had horse cheese, but I'm pretty sure if somebody made horse cheese, I could be like, this is pretty horsey.

• 16:16Kelly Weinersmith?

  You know, I shouldn't have said, eh, because I do think there are cultures who do a lot with horse milk. Just, I don't happen to have come from one.

• 16:23Daniel Whiteson?

  I see. You've never had horse milk yourself?

• 16:25Kelly Weinersmith?

  I have never had horse milk myself. I have a friend who has had fermented horse milk. It was not his bag, but, uh, but you know, it's the bag of many other people.

• 16:34Daniel Whiteson?

  Well, rather than pulling us back from this digression, I'm gonna take us even deeper and ask you, what is the most interesting kind of milk you've ever had?

• 16:41Kelly Weinersmith?

  Interesting. I mean, I don't think, I haven't had that much milk variety. I have had.

• 16:45Daniel Whiteson?

  Never had like beaver milk?

• 16:47Kelly Weinersmith?

  Have you?

• 16:50Daniel Whiteson?

  Would you like animals? You have like 65,000 different kinds of things in your farm? Who knows?

• 16:54Kelly Weinersmith?

  Doesn't mean I'm suckling all the animals I come across.

• 17:01Kelly Weinersmith?

  We, we do joke about, uh, you know, should we try pig milk and get pigs or something? But no, I've had sheep milk, goat milk, and cow milk. And I think that's, those are all, all the milks I've had.

• 17:12Daniel Whiteson?

  Well, I have had pony milk, actually.

• 17:14Kelly Weinersmith?

  Oh, when?

• 17:15Daniel Whiteson?

  Not horse milk. Yeah, there's a little organic store near where we used to live when we were at CERN, and they sell pony milk. And I was always like, what is this? We have to try it in these tiny little bottles. And so, yeah, we, I actually have had pony milk. I forgot about that.

• 17:31Kelly Weinersmith?

  Wait, so wait, so what's the difference between pony milk and horse milk? I just think of ponies as young horses and.

• 17:36Daniel Whiteson?

  Oh, my gosh, Kelly, what?

• 17:37Kelly Weinersmith?

  What, what's, okay, you tell me, horse guy. What's the difference?

• 17:41Daniel Whiteson?

  How far off topic are we now?

• 17:43Kelly Weinersmith?

  Really far.

• 17:44Daniel Whiteson?

  All right, we're gonna have to bring this back and to tell a story about like making fudge with pony milk or something. Ponies.

• 17:56Daniel Whiteson?

  So ponies are not baby horses. That's a foal, right? A baby horse is a foal. A pony is a distinct, fully grown, smaller equine, right? So like, a mature pony is like five feet tall at the shoulder, while a mature horse is much taller than that. So it's sort of like a, you know, it's like a short version of the horse.

• 18:18Kelly Weinersmith?

  But they're the same species, right?

• 18:20Daniel Whiteson?

  Yeah, they can interbreed and their offspring are fertile. But it's sort of like, you know, the difference between a Chihuahua and a Great Dane.

• 18:27Kelly Weinersmith?

  Okay.

• 18:27Daniel Whiteson?

  Right? It's like, a Chihuahua is not a baby version of a Great Dane, right? It's a smaller kind of dog.

• 18:33Kelly Weinersmith?

  All right, all right, all right. Well, thank you for this biology lesson, physicist.

• 18:39Daniel Whiteson?

  All right, all because of my elephant example.

• 18:41Kelly Weinersmith?

  My biology knowledge is a fudge factor, and let's, let's move back to physics.

• 18:47Daniel Whiteson?

  The point I was trying to make is that often we don't understand something, or we understand things partially. And what you want to do the first time is like, make simplifying assumptions and fill in numbers you don't know, and then come back and revisit it. And so you can dig in and understand it better. And so, you know, maybe you want to call that a fudge factor while you're still in the process of figuring it out, but not in a negative sense, not in a misleading sense, right? We're open, we're honest about what we're doing and the status of our understanding. I think fudge factor has too much of a negative connotation for me to say that a first draft of a theory, even with numbers you don't understand, has fudge factors in it.

• 19:27Kelly Weinersmith?

  What would you call it instead?

• 19:29Daniel Whiteson?

  You know, I'd say unexplained constants. You know, for example, we measure the coefficient of friction. When two surfaces rub together, how much force is there on those surfaces because of their friction? And if you didn't understand how friction works, that it's due to the microscopic grabbing and dragging of the little features of those surfaces, you just measure it as a number and say, well, that's what it is. And then if you have a microscope, you can zoom in, you can see, oh, Teflon is a tiny coefficient of friction because it has almost no surfaces. And sandpaper has a high coefficient of friction because look at all these features. And so then you can reveal it, and you can even calculate it from those images.

• 20:10Daniel Whiteson?

  And so that's an example of like, you start with a fudge factor and then you go off and you explain it, you understand it. And so it's not always a bad thing. Sometimes it's just a first step towards a deeper understanding.

• 20:20Kelly Weinersmith?

  So before we take a break, I guess I want to like, jump the gun a little bit and know, is dark energy a like, this is a first step, this is the constant we're using to hold in place, or is it a lot, are we farther than that?

• 20:33Daniel Whiteson?

  Oh, it's so much more nuanced than that, Kelly. You're gonna have to listen to the rest of the episode, sorry.

• 20:37Kelly Weinersmith?

  Oh, man. All right, well, let's take a break so I can work up the energy, and we'll be right back.

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• 25:34Kelly Weinersmith?

  All right, we're back and we're discussing whether or not dark energy is a fudge factor. So Daniel, catch us up. What is, what do we think dark energy is?

• 25:43Daniel Whiteson?

  Yeah, it's important to separate dark energy into two different categories, which are very closely related, but also really importantly different. One is our observation that the universe is expanding and that that expansion has been accelerating for the last five to six billion years. So that's number one. Observation experimentally, and we'll talk about it in more detail, that the universe's expansion is accelerating. Sometimes that's called dark energy. The other side of it is our attempt theoretically to describe that, to make sense of it, to either incorporate it into our theories or to extend our theories to describe it. And that involves something called the cosmological constant. And so

• 26:28Daniel Whiteson?

  those are two big pieces of this concept of dark energy, but it's important to keep them separate because one is something we know, we measure, we see, and the other are theoretical ideas that we're putting together to understand it.

• 26:41Kelly Weinersmith?

  Okay, so tell me more about how we know the universe is expanding and how we like measure this.

• 26:45Daniel Whiteson?

  Yeah, so we've known that the universe is expanding for more than 100 years. Before Hubble and Henrietta Leavitt, people thought the universe was static. They thought, here we have a galaxy and we're just sitting out here in space and stars are stars and that's it. And they didn't even know that there were other galaxies. And it wasn't until Henrietta Leavitt came up with a way to measure the distance to things in the sky, right? Otherwise, it's hard to know. Are you looking at something that's big and bright and far away, or something that's small and dim and close? Those two things look similarly. Until Leavitt figured out how to use cepids, these variable stars, so you can measure

• 27:28Daniel Whiteson?

  how their brightness changes. And by measuring how their brightness changes, you can tell what their brightness actually is. And then you can from that determine how far away they are. So she came up with this method and then Hubble used it and discovered that, oh my gosh, there's a bunch of stuff in the sky that's not even in our galaxy. It looks like it is because it's sort of mixed up there in the sky, but it's actually really, really far away. And that was the first observation that there's stuff outside our galaxy. There's more than one galaxy in the universe, right? Mind-blowing realization. At the same time, he discovered those galaxies are redshifted, that they're moving away from us. So that's when we went from the universe is static to the universe is expanding and everything is moving away from us.

• 28:13Kelly Weinersmith?

  That sounds like an exciting time to be alive and be in science.

• 28:15Daniel Whiteson?

  Yeah. And for like 80 years or so, that's how we thought the universe worked. And the big question in cosmology at the time was, is that expansion gonna turn around? Is there enough gravity in the universe to pull everything back together to make a big crunch? Or is there not enough gravity in the universe and things will slow down but keep drifting forever? Right? Those are the two options, like keep drifting forever and expanding, or slow down, turn around, and come back to a big crunch.

• 28:46Kelly Weinersmith?

  Oh, boy. Existential dread.

• 28:47Daniel Whiteson?

  Yeah. And so to know whether it was gonna be like option A, drift forever, or option B, big crunch, they had to make more precise measurements of the really far away stuff to look like further back into the history of the universe and see how those distances have been changing with time to see, is it look like it's gonna turn over or does it look like it's just gonna keep spreading out? So they developed a new way to measure distances, which are type 1A supernova. These are stars that go supernova, they implode, but they're a special kind of supernova. They're stars that didn't initially go supernova, they just became white dwarfs, they didn't have enough mass in them to go supernova. But then later, they get fed extra stuff from their partners in a binary system, and

• 29:29Daniel Whiteson?

  then they go over the threshold and become supernova. And because of this particular way that they do it, it's very easy to measure from how their light curve goes, how bright they actually are, and therefore how far away they are. So then we got this extra candle that we could use to measure really, really far away stuff. And then we had much more lever arm on our fits to understand the whole history of expansion. Because cepids, these variable stars, tell you about closer up stuff, and type 1 supernova are bright enough to tell you about really far away, really far back in time, longer history.

• 30:02Kelly Weinersmith?

  Okay, I think you lost me on the lever arm thing, but then you summarized the point and I'm with you now.

• 30:07Daniel Whiteson?

  Yeah, well, the point of the lever arm is just like you're trying to understand the trend and you want to be able to predict it. Say, for example, you're looking at like Apple stock and you want to know is it going to go up or is it going to go down? If you only have three days of data, it could go anywhere. But if you have like 50 years of data, you can make a more confident prediction. And so you have a better lever arm. You're like theories are more constrained. And so in order to predict the future of the universe, we had to look deeper into the past. And this was one of my favorite moments in science. It was around 2001. They made this measurement and they asked the universe, okay, is it scenario A that we're going to expand forever? Or is it scenario B, we're going to come back and do a big crunch? And the universe said, no, it's secret option C.

• 30:50Daniel Whiteson?

  It's something you never considered, which is that neither of those things are going to happen. And instead what's happening is that the expansion is accelerating. Both option A and option B suggested the expansion was decelerating. Things were slowing down and the difference was like, is it going to slow down enough to actually go to negative expansion to collapse or just sort of drift out towards slower and slower expansion? But secret option C, which is reality, says, no, the expansion is increasing. It's getting faster and faster every year. And this was mind blowing. This was a crazy idea.

• 31:24Kelly Weinersmith?

  Where were you when you learned this? Cause this was in our lifetime, right?

• 31:28Daniel Whiteson?

  Yeah, absolutely. I was in grad school and I was actually at Berkeley in grad school. And one of the big teams to do this was at Berkeley. Saul Perlmutter was leading that team and he was racing against another team in Australia. It was very exciting. I knew grad students working on that project up at LBL was a big deal. And then of course they won the Nobel Prize like five minutes later. So yeah, it was a big deal at Berkeley at the time. It was exciting, you know? Anytime you find a surprise, those are the best moments, you know? Because it shocks you. It forces you to upend your understanding, you know, to get rid of the dogma and change the mainstream narrative, the kind of thing that like, you know, pops eye misinformation artists are always saying we never want to do. This is our dream come true.

• 32:11Kelly Weinersmith?

  See, I'm imagining grad student Daniel, like taking the whole weekend off, going out into the woods and just staring at the stars with his mind blown for a whole weekend.

• 32:19Daniel Whiteson?

  Yeah. And also being like, why didn't I work on that? Oh my gosh, I could have won a Nobel Prize in grad school.

• 32:25Kelly Weinersmith?

  Whoops.

• 32:27Daniel Whiteson?

  That was the second time I missed a Nobel Prize. I also had the opportunity to go to Caltech and to work on LIGO, the gravitational wave observatory. And I remember visiting and they were like, you should join. It's a really exciting time. And I remember thinking to myself, these guys are crazy. They're never going to see this. Oh my gosh, they're going to work forever and see nothing. And boy, was I wrong.

• 32:48Kelly Weinersmith?

  Oh man. All right. So if you want to know which projects are going to win the Nobel Prize, check out projects Daniel turns his nose up at.

• 32:55Daniel Whiteson?

  Exactly. They have a great track record. And so this is a big surprise. This is shocking. Already invites a lot of wonder and speculation about the cause of it because we're talking about accelerating the whole universe. The amounts of energy required and involved are staggering, right? Absolutely staggering. You need some kind of thing which is going to overwhelm gravity and overwhelm all the other forces. So this is a big new opportunity to learn about the universe. And before people were like, well, are you really sure you want to like upend our understanding of the universe? They're like, let's figure out some other ways to see if this is right. Cause what if you like misunderstood how supernova go or misunderstood something else? And then that's misleading.

• 33:40Daniel Whiteson?

  It's confusing you, right? So what we always love to do in experimental science is find other independent lines of evidence that will either contradict the first ones that tell you like, no, you messed up, that the story's not coherent, or tell you the same story. Cause if you hear the same story from four different ways that aren't related to each other, then it's much more likely that you're hearing the true story. You know, it's like you see elephant poop and you hear elephants and you smell elephants and you see elephant footprints, you probably got an elephant problem.

• 34:11Kelly Weinersmith?

  Yeah, it would be nice to also see the elephant, but sometimes you don't get to do that.

• 34:16Daniel Whiteson?

  And so we've done that. We have other ways to know the universe is expanding and accelerating. One of those is something we've talked about in the show a few times. It's baryon acoustic oscillations. This comes from seeing that the universe used to be a hot glowing soup of matter and light, and it was really dense. And so you think about sound in space, you think, oh, nobody can hear you scream. But back in the early universe, the universe was dense enough that sound could travel through that soup and actually traveled like nearly half the speed of light. It was really, really dense. And so sound traveled really, really fast. And then you had these oscillations where like light pushed matter out and then gravity pulled it back in and then it bounces back out.

• 35:00Daniel Whiteson?

  So you get these oscillations and those create sound waves and you can see those sound waves propagating through the early universe plasma. Because where things were denser, you later on, like billions of years later, you get more galaxies. And where things were less dense, you get fewer galaxies. And when they go out there and they look at the pattern of galaxies in the universe, they can see these rings, these like literal rings in the sky. Those rings are still there because they got frozen in when the universe expanded and the speed of sound dropped. So those sound waves were propagating out and then they got frozen into the universe, into its structure. When the universe cooled and expanded enough that the protons and electrons combined to become neutral.

• 35:43Daniel Whiteson?

  So then they were transparent and they weren't getting pushed by the photons anymore, which changed the whole dynamics and then left this imprint. And so we know when that happened. We know like how big the universe was when they got frozen in. That's like an absolute measure of something like, here's how big it was when it was created. And then we can see how big it is now. And that gives us a standard candle, like a metric, a ruler. So we can use that to see the history of the expansion of the universe because we can see it now, we can see it in early days, we can see it six billion years ago, if we look out into the universe. It's like somebody put a meter stick in the early universe and then we watch it grow through time.

• 36:26Daniel Whiteson?

  And you can just use that to literally measure the expansion of the universe and see it accelerate.

• 36:31Kelly Weinersmith?

  That's amazing. Yeah. So at first I thought you, it was going to be like you, you get two points of time. You can get that point and then where we are now, but you'd need multiple points of time to be able to say it's accelerating.

• 36:41Daniel Whiteson?

  Exactly.

• 36:42Kelly Weinersmith?

  But you've got that. So that's amazing.

• 36:44Daniel Whiteson?

  It's very cool. And then there's another one, which is super cool, which relies on time. These are like cosmic clocks. The idea is to find galaxies who formed stars a long time ago, because stars kind of evolve in a predictable way. Older stars look different from younger stars and we know how long stars last. And so by looking at like, how blue are the stars and how red are the stars? Because blue stars tend to be hotter and brighter and not live as long and red stars are cooler and dimmer and live longer. So as a population of stars age, they tend to go from having some blue stars to having fewer blue stars. So by measuring like, how red is this population of stars, you can get a sense for how old it is.

• 37:28Daniel Whiteson?

  So just by looking at a galaxy, you can age it by measuring the redness and the blueness. Now, if you look at two different galaxies at different redshifts, ones that are further away and ones that are closer, then we're seeing clocks at different points in cosmic history. Right? Their stellar populations have different ages. And so you don't need to know the absolute age of either galaxy. You just need to know the change of age, which comes from their change in redshift. And that tells you the rate at which the cosmic redshift is changing with time. So the galaxies sort of act as clocks that let us measure how fast the universe was expanding when their light was emitted. And you repeat this at like many different redshifts, as you were saying, and you can trace the expansion history.

• 38:13Daniel Whiteson?

  So neither of these are perfect and there's, you know, questions about both of them. One relies on like understanding early universe dynamics. Another one relies on understanding stellar populations and their uncertainties. But the cool thing is that they are different uncertainties. There are questions and things we don't understand that are different in each of those three measurements, but they all paint the same story about the universe's accelerating expansion. So in the same way that like dark matter is not a fudge factor because we have lots of independent evidence for it in all sorts of different ways. People thought of so many different ways to check dark matter and it almost always comes out with the same story. Like yes, there's a lot of invisible matter out there. In this way, we've also checked the expansion of the universe and it tells the same story

• 38:58Daniel Whiteson?

  over and over again, that it's been expanding the whole time. In the very early universe, it was decelerating and about six billion years ago, it turned around and started accelerating, which is amazing. Absolutely amazing.

• 39:10Kelly Weinersmith?

  Maybe this is too much to ask, given the uncertainties associated with each of the different methods that we use that you mentioned earlier, but do these various methods sort of clock the accelerations and the decelerations at the same rate or similar rates? Or is there a lot of variability there?

• 39:26Daniel Whiteson?

  Yeah, great question. And this is connected to a big puzzle in cosmology right now, which is the Hubble tension, which tells us about the rate of expansion. The Hubble constant, which is not a constant, it's a number that changes in time.

• 39:39Kelly Weinersmith?

  Thanks physicists.

• 39:40Daniel Whiteson?

  And to be fair to the physicists and naming, the Hubble parameter, which tells you the rate of expansion is changing, but technically the Hubble constant is just its value now, which is a single number.

• 39:53Kelly Weinersmith?

  Okay.

• 39:54Daniel Whiteson?

  The Hubble constant tells you about the rate of expansion and that changes in time. And so we can measure this in lots of different ways and we don't see total agreement. There are things we still have to figure out there. And I think that's a sign of a healthy field because people are constantly coming up with new ways to measure this. And the overall story is the same. We know this expansion. We know that expansion is accelerating. There are differences in those expansion rate measurements in early universe and in late universe. And it requires more complicated theories than some of the simple theories that we'll talk about in a minute. And so, you know, whether you expect that expansion to be constant in time or not is a subtlety that you have to address when you build your theory of why this is happening.

• 40:37Daniel Whiteson?

  But yeah, there's also some fuzziness and disagreement about the measurements themselves.

• 40:41Kelly Weinersmith?

  Well, I still think we're very clever apes that we figured out any of these methods of trying to explore what's happening in our universe.

• 40:48Daniel Whiteson?

  I know, from this tiny little rock that we basically never left, just by gathering photons that happened to come our way, we figured out this incredible cosmic story that's so much bigger than us. It's amazing what people can do. As Hazel says, you know, science is just like looking around and figuring out what happened.

• 41:08Kelly Weinersmith?

  I mean, but that, that's a profound question. What happened?

• 41:11Daniel Whiteson?

  What happened? Exactly. I love the way she minimizes it. She's like, you know, you're just figuring out what happened. I'm like, yes, what happened to the whole universe?

• 41:20Kelly Weinersmith?

  That's right. Or, or, you know, through the evolution of our species, there's lots of what happened questions that we want to answer. Okay, so you mentioned that there's sort of two different things people are talking about when they mention dark energy. And the first is the fact that the universe's expansion is accelerating. So we've talked about that. So let's take a break. And when we come back, we'll dig into this cosmological constant idea.

• 41:52Daniel Whiteson?

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• 46:35Kelly Weinersmith?

  And we're back. And we're talking about whether or not dark energy is a fudge factor. And the second thing that people are usually referring to when they say dark energy is this idea of a cosmological constant.

• 46:47Daniel Whiteson?

  Yeah.

• 46:47Kelly Weinersmith?

  So, Daniel, what's the cosmological constant?

• 46:51Daniel Whiteson?

  Yeah, so we want to understand, how could the universe's expansion be accelerating? What's doing that, right? And there's a really interesting history here, which goes all the way back to the beginning of the story we told about when people thought the universe was static. So Einstein came up with his theory of general relativity, which tells us about space and time, and how things pull away from each other or expand also. And this theory, general relativity, it predates Hubble and Levy. Their discovery that the universe was expanding, that wouldn't come for a long time, many years after Einstein developed his theory of general relativity. So Einstein was dealing with the assumption that the universe was static. And when he put his theory together, he was like, all

• 47:35Daniel Whiteson?

  right, so mass bends space, the universe is filled with mass, so it should curve space and pull stuff together. And then he thought, hmm, well, why hasn't the universe collapsed? Right? Like, if space is filled with all this mass, why hasn't it all crunched down? So his theory essentially predicted the universe should have collapsed already. But he looked out and he said, no, the universe is static, so what's going on? Well, there's another knob in his theory. General relativity tells us that space is bent by mass. And the sort of pop side level understanding of general relativity tells you, like, you can think of the force of gravity as the bending of space. But general relativity is much more than that. Different kinds of energy enter into general relativity in a different way.

• 48:19Daniel Whiteson?

  So for example, if you have internal stored energy, what we call mass, that does bend space and does pull things together effectively, although they're actually in free fall. But if you have another kind of energy, stored potential energy that just fills space, that actually makes space expand. So general relativity broadly doesn't just pull things together, it can also create expansion.

• 48:44Kelly Weinersmith?

  Okay. And he recognized that at the time? Question mark.

• 48:49Daniel Whiteson?

  He knew that at the time. And so he thought, all right, what if I just stick a number into my theory? If I add potential energy to the universe, no explanation, no idea what it's referring to, just a fudge factor, put that in to balance gravity, so that the universe is then static. Because that's what he wanted to achieve. He wanted to describe the universe. He wanted to see if his theory was compatible with the universe. And like, is that a bogus thing to do? No, it's just essentially asking, well, what would I have to put into my theory to make it describe the universe as I think it works? And remember, he was working on a false premise. He was trying to describe a static universe, because that's what they thought we lived in at the time, but they were wrong.

• 49:31Kelly Weinersmith?

  The OG fudge factor.

• 49:32Daniel Whiteson?

  Yeah, exactly. So the OG fudge factor was put in to make general relativity agree with the misunderstanding at the time that the universe was static. The other problem with this fudge factor is that the universe, as he described it, had these two competing things, the cosmological constant pushing out and gravity pushing in. And for that to give you a static universe, they had to be perfectly balanced. So the universe is like on a knife's edge. It's not stable at all. Somebody like drops an extra raisin in the universe, boom, it collapses. You get a tiny smidge more potential energy, boom, it expands. So it doesn't really make sense as a model of the universe.

• 50:12Kelly Weinersmith?

  One more reason to hate raisins.

• 50:13Daniel Whiteson?

  I know. Wait, hold on a second. I love raisins. What are you talking about?

• 50:18Kelly Weinersmith?

  No, you're wrong is what I'm talking about. Yeah, no, raisins and cookies are why I have trust issues.

• 50:24Daniel Whiteson?

  That's only because you think they're chocolate chips, and then you're disappointed. But if you're expecting raisins, then you're like, yum, raisins.

• 50:32Kelly Weinersmith?

  No, then I'm mad at whoever thought I would like raisin cookies. They don't know me at all.

• 50:37Daniel Whiteson?

  Well, the answer is to put raisins and chocolate chips into your cookies.

• 50:40Kelly Weinersmith?

  Oh, no.

• 50:41Daniel Whiteson?

  Porque no los dos.

• 50:42Kelly Weinersmith?

  Because then you've ruined, you've ruined the cookie with the raisins. All right, we've had milk digressions, raisin digressions. We should start a food podcast.

• 50:50Daniel Whiteson?

  So then Hubble and Levy discovered the universe is actually expanding and this whole point of putting in a cosmological constant to describe a static universe. Yeah, that was a mistake. And Einstein said, okay, I'm going to get rid of the cosmological constant. And instead, I'm just going to assume that the universe is decelerating. It's currently expanding, but it's decelerating. So here we're distinguishing between essentially velocity and acceleration. So think about how your car operates. You can have forward velocity. You're going at 50 miles an hour and you're hitting the brakes. You're decelerating, so you're slowing down. You're still moving forwards, but you're slowing down. That's what Einstein assumed was happening. He said, okay, the universe isn't static. The car is not just sitting on the highway.

• 51:33Daniel Whiteson?

  It's moving forward and gravity is slowing it down. And so he thought eventually it will crunch. Right? That was his supposition, but he didn't need cosmological constant anymore and he got rid of it.

• 51:45Kelly Weinersmith?

  Okay. And this was in response to information he learned in his lifetime. He went from thinking the universe was stable to decelerating. Okay.

• 51:52Daniel Whiteson?

  Yeah. And that's the origin of his comment. I don't know the exact quote, that the cosmological constant was his greatest blunder. You know, that he put it in and then he had to take it out.

• 52:03Kelly Weinersmith?

  We all make mistakes.

• 52:04Daniel Whiteson?

  Yeah. Now 80 years later, we discover, okay, the universe isn't just expanding. It's expanding and accelerating. Right? And so now people are searching for a theoretical reason that might happen. What could accommodate that? Not just that it's accelerating, but that it started accelerating recently. Right? That the history is that we were always expanding, but that expansion was decelerating for the first nine billion years. Gravity was winning. And then around five billion years ago, nine billion years into the history of the universe, it turned around and it went from decelerating to accelerating. So like the car was always moving forward, but it was slowing down the first nine billion years. And then we went from brake to gas and now we're accelerating.

• 52:48Daniel Whiteson?

  We're still moving forward, still expanding, but now that expansion is faster and faster.

• 52:52Kelly Weinersmith?

  And somebody was like, would you like a cookie with raisins in it? And you put your foot on the gas to get out of there as fast as you can. The universe is trying to escape raisin cookies.

• 53:01Daniel Whiteson?

  I am driving as fast as possible to the oatmeal cookie factory.

• 53:05Kelly Weinersmith?

  No, huge mistake.

• 53:06Daniel Whiteson?

  So I can consume them as quickly as possible.

• 53:08Kelly Weinersmith?

  Huge mistake.

• 53:09Daniel Whiteson?

  And so the cosmological constant can actually describe this. It's amazing because the cosmological constant says, look, you got some potential energy that fills space. We don't know what it is yet, but say you have something that fills space with potential energy. That will cause some expansion. And the amazing thing is that as the universe expands, matter gets more diluted, radiation gets more diluted. Right? By which I just mean like you got more space and the same amount of stuff. So the density of matter goes down, which means essentially gravity is decreasing, but potential energy doesn't. It's just built into space. So if you get twice as much space, you get the same density of potential energy everywhere, which means more energy.

• 53:52Daniel Whiteson?

  So as the universe expands, the cosmological constant becomes more and more important because everything else has energy density that's decreasing with expansion, but it's staying constant, which means that it gets a larger and larger fraction. So expansion leads to more expansion because as time goes on, as the universe expands, the cosmological constant becomes more and more important, which according to the equations of general relativity means more expansion until at some point it starts to win and it's overwhelming everything. And that's what happened five billion years ago. So it actually goes to accelerating expansion or runaway effect. And this predicts that as time goes on, it's just going to get more and more important. We're in a dark energy dominated universe.

• 54:36Kelly Weinersmith?

  So my brain is trying to make a connection to Noether and her there. Did she play a role in helping us understand this?

• 54:44Daniel Whiteson?

  So she didn't help us understand it, but she helps us understand the implications. Because you're probably remembering that Noether has her amazing theory about conservation laws and symmetries. And there's a connection between whether the laws of physics and space are constant in time and conservation of energy. And she says, if space is not expanding and the laws of physics don't change, actually, if the action is invariant over time, then energy is conserved. Check out our whole podcast episode about action, if you want to learn more about that. But now we know that the action is not invariant, that as time goes on, space is expanding and accelerating. And that's how we know that energy can't actually be conserved in our universe.

• 55:25Daniel Whiteson?

  It shouldn't be conserved in our universe because the symmetry that you would need to get energy to be conserved is broken. Right? Space is expanding. The action is not invariant. So that's the connection to Emmy Noether. Is that what you're asking about?

• 55:40Kelly Weinersmith?

  Yeah. And so I guess now I'm trying to connect that to, so as the universe is expanding, you're getting more dark energy being made.

• 55:47Daniel Whiteson?

  Yeah.

• 55:48Kelly Weinersmith?

  Is that the same thing as the cosmological constant? Or is that like a part of understanding the cosmological constant?

• 55:54Daniel Whiteson?

  It's a great question because that's the essential piece of this theory that helps us make it work, that as the universe expands, cosmological constant is constant. It's a constant density. Right? It does not get diluted. That's the reason that it works. And it's sort of amazing that our theory of general relativity already has a knob in it, which if you crank it up to a certain number, explains perfectly, well, not perfectly, but very, very well, this accelerating expansion of the universe. You don't have to reach for totally crazy new theory of physics, but what you do need is potential energy that fills all of space and doesn't get diluted. And that's the big mystery. So we've made sort of a step forward by saying like, oh, there's a feature of general

• 56:38Daniel Whiteson?

  relativity which can create this thing which we've observed, which we know is happening, but it also kicks the can down the road and invites more questions like, well, what is this potential energy? You just like put it in there. You haven't said what it is. Like potential energy is not just some abstract thing. You know, you can have potential energy stored in a field, for example. Like we know that the Higgs boson is a particle that's an oscillation in a field that's out there. And one of the most interesting things about the Higgs field, the reason it does what it does is because it's filled with potential energy, unlike other fields. The photon field and the electron field don't have this kind of potential energy, but the Higgs does. It's potential energy that fills all of space. And you might think, oh, wow.

• 57:22Daniel Whiteson?

  Is the Higgs boson field providing the potential energy you need to explain the cosmological constant? Wouldn't that be incredible? If you came out from one direction, you're like, hey, the universe is expanding and that suggests maybe there's potential energy in all of space. And you came out from the other direction, you're like, hey, particle physicists have discovered a field that fills all of space with potential energy. And you might be like, oh my gosh, am I about to make the best understanding in the history of the universe? And you put these two numbers together and say, do they agree? And the answer is no.

• 57:52Kelly Weinersmith?

  Oh.

• 57:53Daniel Whiteson?

  And not even to within 10% or 50%. They're different by 10 to the 120.

• 57:59Kelly Weinersmith?

  And so let me guess, this is a project you decided you wanted to be part of because it was destined to not get a Nobel Prize.

• 58:07Daniel Whiteson?

  Oh my gosh. Understanding theoretically the source of dark energy would definitely get somebody the Nobel Prize. And so we have no explanation. Right? We have this mechanism, the cosmological constant, which if you put into general relativity can explain the accelerating expansion of the universe, but we have no idea what the cosmological constant really is. It's just like a first idea. It's a number we put in to make things work. And then we come back and say, well, what could be causing it? And our first idea, all the quantum fields that we know about, definitely is not explaining that. That does not work.

• 58:41Kelly Weinersmith?

  No.

• 58:41Daniel Whiteson?

  We don't have another better idea yet. So is that a fudge factor? I mean, I think it's a little bit of a fuzzy question because it's not a bad fudge factor. It's not like, hey, we discover the universe is expanding and accelerating and we really want to stick with general relativity. So we're going to do anything to make it work and we're just going to stick this number in here. We're going to pretend it makes sense, even though it doesn't. Right? That's the like cartoon version of conspiratorial physicists trying to defend general relativity or something. I mean, which makes no sense because in reality, everybody, especially the conspiracy folks out there are trying to disprove Einstein.

• 59:16Kelly Weinersmith?

  Yeah.

• 59:17Daniel Whiteson?

  Like I get Einstein was wrong emails 10 times a day. So I don't know why they think that like, you know, physicists don't also want to disprove Einstein.

• 59:25Kelly Weinersmith?

  Cause then your face would be on all the posters. What would your quote be, Daniel?

• 59:31Daniel Whiteson?

  My quote would be, this is never going to work. Dana was wrong again.

• 59:34Kelly Weinersmith?

  Oh, I'd put that poster up.

• 59:38Kelly Weinersmith?

  Good to always be skeptical.

• 59:39Daniel Whiteson?

  And the issues go deeper, right? It's not just that we don't know where this number, the cosmological constant, comes from. Like, we'd love to be able to derive it from first principles to say, oh, the Higgs field, and you calculated it, here's the potential energy, and here's the number you put in, and it works. We're not there yet, we're nowhere close to there. The other issue is that, as I was saying earlier, even just having a single number, the cosmological constant, doesn't quite work because we see the number you would need changing over time a little bit, like the early universe measurements, the late universe measurements. So it might be that there's two different kinds of expansion happening there.

• 1:00:17Kelly Weinersmith?

  Oh.

• 1:00:18Daniel Whiteson?

  So there's a theory of like, early dark energy, that is like another kind of dark energy that turned on early, kicked things off, and then turned off, right? Which maybe explains why we're seeing inconsistent measurements. So there's like, complexity to this fudge factor. And there's, you know, even other people out there with totally different theories. Like, a couple of years ago, there was all this excitement because people noticed a correlation between supermassive black holes at the hearts of galaxies and the expansion of the universe, and the accelerating expansion. And so there was thought for a while, like, maybe supermassive black holes in the hearts of galaxies are the dark energy, maybe somehow they are doing this to the universe. And there were some problems with that theory, and it sort of went away.

• 1:01:01Daniel Whiteson?

  But, you know, what it shows you is not a field that's out there to convince you of one idea, whether or not it works, but it shows you a group of people being curious about the universe, scratching their heads, being open about what works and what doesn't work, like, the big mysteries that, you know, we write 10,000 Pops Eye articles about a year, the Hubble constant and all this kind of stuff, are open about what's not working, and it's a work in progress, and it's a work in progress that's out there in public, right? You can see people making progress, people disagreeing about it, people suggesting new ideas. There's no, like, defense of the dogma here. This is just like, you're watching it in action, you know? Welcome to the forefront of ignorance. This is how science works, right?

• 1:01:45Daniel Whiteson?

  We're confused about how stuff is happening, and we're trying to figure it out. There are some older questions that we're much less confused about, and we're not very excited about revisiting, like, is the speed of light constant? You know, maybe we're wrong about that, I don't know, but it doesn't seem as interesting as other questions that we know we're wrong about, and we have no explanation for, like, you know, what is the source of dark energy theoretically? So that's why some questions get more attention and other questions get less attention because, hey, we're humans, and we're driven by our curiosity, and curiosity is frankly, subjective and personal, and, you know, driven by what gets you excited to get out of bed and spend your day doing science.

• 1:02:25Kelly Weinersmith?

  Yeah.

• 1:02:26Daniel Whiteson?

  All right, end rant.

• 1:02:28Kelly Weinersmith?

  Well, and this is the process, you know? You do what you can with the information you have, you try to collect more information so that you can ask more specific and better questions, and sometimes you're gonna be wrong, you just always need to be open to that.

• 1:02:40Daniel Whiteson?

  Yeah.

• 1:02:40Kelly Weinersmith?

  And you move forward the way you can.

• 1:02:42Daniel Whiteson?

  Yeah. And, you know, let's also acknowledge that there are structural incentives in science and in every human endeavor for people to defend an idea even after we're clear it's not working. You know, there are people who have an idea and stake their reputation on it, and, you know, it was their baby, and when it doesn't look like it's working, they try to make it work, and they stick to it, and there are definitely structural incentives for people to not do the right thing. But, you know, people have lots of incentives, and they're not always necessarily just gonna follow one set of incentives. There are also incentives to figure out how things work and to be a reasonable human being, and in reality, people's actions are complex, and this is not a perfect system,

• 1:03:26Daniel Whiteson?

  and I don't want to suggest that, like, science is a pure meritocracy, and every idea rises to the top perfectly, and that we always work on the most useful thing. Absolutely not. It's a messy, political, human endeavor, but it's also the best system we've ever had for building knowledge about the universe. So, anyway, I was supposed to end my rant a minute ago, but this is the real end.

• 1:03:47Kelly Weinersmith?

  That's rant part two. But I mean, there's, there's like, you know, different people have different incentives. So if you've got somebody whose incentive is to, like, not back down even when it's clear that their theory isn't explaining things as well as they thought, there's an incentive for the, like, lab at the other university across the pond to prove you wrong. Or there's the incentive of your grad students who, like, maybe, you know, when they start their own lab, realize, I'd really like to be remembered as someone who was right. And so, you know, maybe they slowly push back against, you know, the ideas of their advisor because they don't want to spend their whole careers on an idea that's wrong. And so, you know, it's, different people have different motivations, and hopefully, in the end, science pushes everybody towards the right answer.

• 1:04:28Daniel Whiteson?

  Yeah, and, you know, another note for people who have ideas that they're excited about, and they can't get the community to engage, you know, you've written grant proposals, and they've all been rejected, or nobody will read your theory, like, remember that resources are limited, right? In a perfect world, we could give everybody money to investigate the universe, no matter whether their theories were popular or not, but we have limited funding, we have limited time, we have limited attention, we have to make decisions about where to put those resources. And so, rather than having, like, one random YouTuber decide, this is what's most important, and everybody else is wasting their time, we have panels, we have consensus, we argue over it, we do it in public, so that we try to get as many perspectives as possible.

• 1:05:12Daniel Whiteson?

  But in the end, yes, we do want to put resources towards the things we think are going to lead to discoveries, and that means investing in the mainstream ideas, not always giving money to everybody out there with a crazy new idea, which may be promising and may even be correct, right? But in the same way that, like, the best screenplays aren't always turned into movies in Hollywood, right? Like, the system isn't perfect because of limited resources.

• 1:05:38Kelly Weinersmith?

  Yeah.

• 1:05:38Daniel Whiteson?

  And that's just the unfortunate reality, and the way to fix that is not to burn academia to the ground, but, but to spend more money, to fund more of these ideas further from the mainstream, right? If we instead invest in academia, then we get more crazy blue sky ideas, we can take more risks. Anyway, for the third time, I'll say end rant, then.

• 1:05:59Kelly Weinersmith?

  Yeah, yeah, sure. We'll see, we'll see.

• 1:06:03Daniel Whiteson?

  I should stop saying that.

• 1:06:05Kelly Weinersmith?

  It's like when you, when you title a document, or, you know, a grant or a manuscript, final version, you are making it certain that there will be a final version two and a final version three. But, okay, to try to bottom line, we have this observation that we feel pretty darn confident about, because we've seen it using a bunch of different methods.

• 1:06:24Daniel Whiteson?

  Yes.

• 1:06:24Kelly Weinersmith?

  We're doing our best to explain it, we realize that there's shortcomings in our explanations, we are trying to figure it out, it is an open conversation.

• 1:06:32Daniel Whiteson?

  Yeah.

• 1:06:33Kelly Weinersmith?

  And this is one of the big, exciting questions in physics that, you know, hopefully we'll figure out in the next generation or two, or this generation.

• 1:06:40Daniel Whiteson?

  Yeah.

• 1:06:40Kelly Weinersmith?

  And if Daniel thinks the lab is probably not on the right path, those guys and gals are getting a Nobel Prize.

• 1:06:47Daniel Whiteson?

  That's my backwards seal of approval, exactly.

• 1:06:50Kelly Weinersmith?

  That's right.

• 1:06:50Daniel Whiteson?

  All right, well, thank you, everybody, for going on this journey with us, back into history, to our understanding of the universe, and how the universe evolves, and how our understanding of it has evolved, to try to predict the future, and how our understanding will eventually, we hope, coalesce into a crystal clear picture of the history and future of the universe.

• 1:07:10Kelly Weinersmith?

  Good luck, physicists.

• 1:07:19Daniel Whiteson?

  Thanks, everybody, for listening. Please go and do us a favor and rate the show on whatever podcast app you're using, it really helps people find us.

• 1:07:27Kelly Weinersmith?

  Daniel and Kelly's Extraordinary Universe is edited by the amazing Matt Kesselman.

• 1:07:32Daniel Whiteson?

  He really is a wizard. You can also find us online on Blue Sky, Instagram, and X, D and K Universe. Come engage with us.

• 1:07:42Kelly Weinersmith?

  You can email us at [email protected]. We really do want to hear from you.

• 1:07:48Daniel Whiteson?

  And you can find our website, www.danielandkelly.org, where you'll also find an invitation to join our Discord, where everybody comes and talks about the amazing universe.

• 1:07:59Kelly Weinersmith?

  And we also have the most amazing moderators. This is an iHeart Podcast. Thanks for joining us.

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