How Politics And Beauty Leads Physics Astray | Sabine Hossenfelder

1. 0:00 – 15:00

   (wind blowing) Hi, friends. This…

   1. CWChris Williamson0:00

      (wind blowing) Hi, friends. This week, I am talking to a theoretical physicist.

   2. NANarrator0:10

      (music)

   3. CWChris Williamson0:10

      Bit of a departure from my usual sort of guests, which is very interesting. Sabine Hossenfelder is a theoretical physicist, blogger, and author. Her most recent book, Lost in Math: How Beauty Leads Physics Astray, talks about physicists' obsession with beautiful theories, and how this is potentially leading to a restriction in progress for physics overall. (laughs) Now, it sounds like quite a nebulous and difficult to define area, and it turns out that it actually is, but we do a pretty good job of working out just what is happening in the physics world at the moment. What I found to be particularly interesting was discovering just how much politics influences physics to get your research funded, what the hurdles are that you need to jump through, and who, uh, whose rings you need to kiss (laughs) in order to be supported. It- it- it seems very contradictory to think that a scientific subject area requires people to play a game akin to what you would presume in Wall Street, where you're sticking to the right kinds of rhetorics, and you're pushing the correct narrative coming from the right educational background, coming from the right conceptual, theoretical background. Really, really interesting, and it was, um, a whole world that I didn't even know (laughs) existed. So, here we go.

   4. NANarrator2:07

      (music)

   5. CWChris Williamson2:10

      Sabine Hossenfelder, how are you today?

   6. SHSabine Hossenfelder2:14

      I'm doing fine. How are you?

   7. CWChris Williamson2:15

      Very good. Thank you. Where are you in the world at the moment?

   8. SHSabine Hossenfelder2:18

      I'm in Heidelberg. That's like 100 kilometers south of Frankfurt.

   9. CWChris Williamson2:24

      Oh, very nice indeed. Very nice. So, I wanna get straight into it. You will be the first physicist which we've featured on the podcast.

   10. SHSabine Hossenfelder2:34

       (laughs)

   11. CWChris Williamson2:34

       Uh, so you- the- the weight of the entire world of physics is resting on your- (laughs)

   12. SHSabine Hossenfelder2:38

       (laughs)

   13. CWChris Williamson2:38

       ... shoulders at the moment. Um, I wanna ask a really fundamental question. It's been a really long time since we've seen major breakthroughs in physics, you know, global, newsworthy breakthroughs. I- is there a reason why that's the case?

   14. SHSabine Hossenfelder2:56

       Well, one of the reasons is probably that you're reading the wrong news. (laughs)

   15. CWChris Williamson3:01

       (laughs)

   16. SHSabine Hossenfelder3:01

       Um, there have been a- there have been a lot of breakthroughs in physics. Uh, what I'm mo- mostly concerned with are really the foundations of physics. So, uh, the biggest breakthroughs in physics are the ones that the Nobel Prizes are getting handed out for, and you find a list of that on the website of the Nobel, uh, Prize Academy. Um, but I'm- I'm really talking about the foundations of physics, and there, you are right, it has been a really long time since there has been a breakthrough where we have discovered something really new. I mean, the stuff that has made headlines, like say the- the direct detection of gravitational waves, or, um, you know, neutrino masses, neutrino oscillation and so on and so forth, these are all ideas that go back at least 30, 40, in some cases 100 years.

   17. CWChris Williamson3:46

       So, this is physical proof of something which theoretically has been around for a little while?

   18. SHSabine Hossenfelder3:53

       Yes.

   19. CWChris Williamson3:54

       Okay. So, uh, is it a case at all that there's less stuff "to discover," in quotation marks? Are we mapping so much of physics that the remaining dark spots on the map are, uh, are limited? Or is it something to do with the approach that physicists have got at the moment, or is there a- a sticking block or a glass ceiling that we've hit?

   20. SHSabine Hossenfelder4:17

       Well, that's a very good question, but how would I know? (laughs)

   21. CWChris Williamson4:20

       (laughs)

   22. SHSabine Hossenfelder4:20

       How would I know what- what is still left to discover? What I can tell you is that, um, we have already discovered a lot, and that just means that the easy things have been done, uh, you know, the stuff that you can m- measure in your little laboratory with, uh, your handheld equipment and so on and so forth, that's all been done. Um, that's the case in experiment. It's also the case in theory development, you know, the easy things have been tried. So, it's kind of natural to expect that it will become more difficult. Um, then on balance to that, though, we also now have a lot of m- more people working on it, uh, so that should help. Uh, but apparently it doesn't.

   23. CWChris Williamson5:00

       (laughs)

   24. SHSabine Hossenfelder5:00

       So, we have, uh, at least in the foundations of physics, um, we have had the mathematical structure of the theories that we're using right now since the mid-1970s.

   25. CWChris Williamson5:12

       Okay. So, the low-hanging fruit, to one degree or another, as- as low-hanging as physi- physics can get, I suppose, has been- has been gathered to a large degree. Would you say that's fair?

   26. SHSabine Hossenfelder5:23

       Yeah, certainly.

   27. CWChris Williamson5:25

       Okay. So, what- what's the- what is the current sticking point that we've got at the moment? Is it technological? Is it that the instrumentation that we're using? Is it the minds? As you say, there's more- more people than ever are dedicating their efforts towards physics. Are they looking in the wrong place?

   28. SHSabine Hossenfelder5:47

       Well, I- I do think that they are looking in the wrong place. But, uh, of course, I don't know, you know? I- I don't know what's the right thing to do. Uh, but the question that we can reasonably look at and try to answer is, uh, whether they are using good scientific methods that would give them the highest probability of making progress, and I think that's just currently not the case.

   29. CWChris Williamson6:09

       Okay. Well, let's expand on that then. Why- why is that not the case?

   30. SHSabine Hossenfelder6:15

       Well, um, we have seen a lot of null results in the foundations of physics in the last four decades. Um, for example, in the search for dark matter, um, this has been going on since the mid 1980s-
2. 15:00 – 30:00

   Wow, so that's potentially…

   1. SHSabine Hossenfelder15:00

      and ask if one of the assumptions that entered all these arguments that led them to work on supersymmetry to begin with was maybe the wrong path to take.

   2. CWChris Williamson15:11

      Wow, so that's potentially a- an awfully big upheaval in the physics community, I'm gonna guess.

   3. SHSabine Hossenfelder15:17

      Well, you see people discussing this right now. So the argument that I make in my book is that this, uh, belief in naturalness is an issue, um, and that's a problem that needs to be rethought right now. So naturalness is this idea that the theories of physics should only contain numbers without units that are close to one, not much larger than one or not much smaller than one. Th- there are more complicated versions of this, but that's, that's the one- the easy case. (laughs)

   4. CWChris Williamson15:48

      Yeah, yeah.

   5. SHSabine Hossenfelder15:49

      Um, and, um, that's something that they use to construct theories. And now, it, um, just happens that supersymmetry, um, obeys this idea of naturalness. It actually helps to make the standard model natural. So the standard model, by itself, is not natural, but if you add supersymmetry to it, it works. And, uh, a lot of theoretical physicists take that as strong evidence that there's something true about supersymmetry, that it has power to describe nature. And I just think that that's a wrong conclusion, you know? I see no reason why the theories of nature should have this property that they call naturalness.

   6. CWChris Williamson16:32

      Okay. So, in your book, uh, Lost in Math: How Beauty Leads Physics Astray, you talk about this, um, this desire within the physics community to have beautiful theories. Can you describe what, what is considered to make a theory beautiful?

   7. SHSabine Hossenfelder16:52

      Y- yes. So it's interesting that if you ask theoretical physicists what they mean by beauty, they all more or less say the same thing. (laughs) Um, so I, I think this is not, um, an idea of beauty that you find, uh, find among non-physicists, um, but for what physicists are concerned, uh, beauty has three major ingredients. The one is simplicity, and by this I mean that the theory should be simple in absolute terms. I don't mean in, in relative terms where you say, "Well, I take the theory that is simpler than some other theory-

   8. CWChris Williamson17:25

      Yeah.

   9. SHSabine Hossenfelder17:25

      ... but achieves the same." But it, but just that the, the theory should have simple laws, like it should have... Unified force, for example, is simpler than four different forces. Um, if you add symmetry to a model, that usually, um, combines two different concepts to one or several different concepts. Like with supersymmetry, we already talked about this, where you have the fermions and the bosons, they actually belong together.

   10. CWChris Williamson17:51

       Mm-hmm.

   11. SHSabine Hossenfelder17:51

       So that, that's a simplification in terms of the axioms of your theory. So simplification is one aspect of beauty. Then there's naturalness. I already told you about naturalness, the thing with the parameters that have no units, that should be of ￰.

   12. CWChris Williamson18:07

       Yup.

   13. SHSabine Hossenfelder18:08

       And then the, the third aspect is something that's usually referred to as elegance, and that's, uh, kind of a fluffy criterion- (laughs)

   14. CWChris Williamson18:16

       (laughs) Ve- very much so. It's not something I heard, I expected to hear coming out of physics.

   15. SHSabine Hossenfelder18:20

       (laughs) Well, it's, it's something that they, uh, talk about a lot, and you actually find this also in a lot of, um, older literature. Like there's, uh, there's a book by Chandrasekhar where he- where he goes on about this already.... but, um, so, what they mean with elegance is that the theory should be simple, but it shouldn't be too simple. So, it should lead to some interesting insights. You should, you should have some aha effect here and there, you know? It, it should have unexpected connections. It, um, should give you some surprises. So, that's this idea, um, of, of elegance. And you also find these three aspects in a lot of artworks, uh, by the way. I mean, um, simplicity is all well and fine, but if it's too simple, it's just boring. (laughs)

   16. CWChris Williamson19:04

       Mm-hmm.

   17. SHSabine Hossenfelder19:05

       And, and so, I think it's the same sense, um, that y- you find here.

   18. CWChris Williamson19:10

       That's really interesting. It sounds like reducing the theory down to its simplest, simplest possible terms is, is, um... (sighs) Does this cause people to... Does this cause physicists to look in the wrong places sometimes when they're trying to develop theories? Is this a- an artifact of E equals MC squared and other very, very short, very, very simple theories like that?

   19. SHSabine Hossenfelder19:36

       (laughs) You know, I would actually say that E equals MC squared is too simple. You know, it's not elegant enough. (laughs)

   20. CWChris Williamson19:41

       That's gone... That's o- that's, that's overshot it. Okay, so that's interesting.

   21. SHSabine Hossenfelder19:43

       Yeah, yeah. But, but that makes an interesting point because th- this sense of what is elegant, um, you know, what is surprising, what, what gives you some, uh, new insights and so on depends, of course, on how much you know already. So, the sense of what counts as elegant and what counts as beautiful changes, um, throughout the history of science. Y- you find evidence for this in the literature.

   22. CWChris Williamson20:05

       Mm-hmm.

   23. SHSabine Hossenfelder20:06

       You know? When y- you look back, uh, several hundred years, they thought that planets on circular orbits, well, that's a beautiful idea, also turns out to be wrong.

   24. CWChris Williamson20:13

       (laughs)

   25. SHSabine Hossenfelder20:14

       (laughs) But, uh, that- that's an ideal of beauty that you just wouldn't find today among physicists.

   26. CWChris Williamson20:20

       Yeah.

   27. SHSabine Hossenfelder20:20

       It's, it's something that no one would, uh, pull upon. Uh, now they have other ideas of beauty and, well, maybe these work or maybe that these don't work. We just don't know. So, generally, I think it's a bad idea to impose, um, our current ideals of beauty on the laws of nature in the sense that we use it to construct new theories. Because the problem is, you know, we were talking about these experiments earlier where they look for dark matter and, and the particle colliders and, uh, I don't know, some telescopes and so on and so forth. These are really costly experiments, and we just can't test all theories that, uh, theoretical physicists come up with. So, we have to make a selection. Uh, and of course, we try to select those theories that we consider to be the most promising. Now, if we make a bad choice, we go and test theories, um, that are wrong, then the only thing we get are null results. Now, the null results are also results, of course, um, but they are not very useful results when you try to develop a new theory.

   28. CWChris Williamson21:25

       Mm-hmm.

   29. SHSabine Hossenfelder21:27

       So, that, that gets you stuck in a cycle where looking at the wrong theories (laughs) gives you null results that gets you stuck at the wrong theories and so on and so forth.

   30. CWChris Williamson21:37

       Yeah. Well, it's-
3. 30:00 – 45:00

   Yep. …

   1. SHSabine Hossenfelder30:00

      in much, much better details than was previously known and found a few surprises there. People are working on it. It has also been able to measure a lot of the constants in the standard model of particle physics to much higher precision than what was previously possible. It has also measured a lot of composite particles, um, that are made of, uh, several quarks and measured their properties. So, it, it's not like nothing hasn't been going on besides the Higgs boson. (laughs)

   2. CWChris Williamson30:31

      Yep.

   3. SHSabine Hossenfelder30:31

      Uh, uh, it's just that the other stuff has not been quite as exciting as producing a tiny black hole that eats up Europe.

   4. CWChris Williamson30:38

      (laughs) Yeah. Well, I mean, that would have made the news if it had happened. It would have definitely-

   5. SHSabine Hossenfelder30:45

      If, if, if there would have been still news then, yeah.

   6. CWChris Williamson30:47

      Y- yeah, exactly. News in America, perhaps. Um, but that is... I am right in saying that that's the only new particle which it found. That's correct, right?

   7. SHSabine Hossenfelder30:54

      The only new fundamental particle, yes.

   8. CWChris Williamson30:57

      Okay. Um, is there a likelihood or is, uh, uh, people still holding out hope that it's going to find more, or again, have we hit a, a little bit of a glass ceiling with, with that particular, uh, that-

   9. SHSabine Hossenfelder31:08

      Oh, yes. Oh, yes, definitely. Um, there are still people who think that, uh, supersymmetric particles will eventually show up. Um, so the thing is that this assumption of naturalness that I was talking about earlier would have put the supersymmetric particles in the regime, um, of fairly low energies close by the Higgs, basically. So, we should have seen them already.

   10. CWChris Williamson31:32

       Okay.

   11. SHSabine Hossenfelder31:32

       So, we know that this idea of naturalness was just wrong-

   12. CWChris Williamson31:36

       Mm-hmm.

   13. SHSabine Hossenfelder31:36

       ... and it's gone out of the window, but nothing has replaced it. And this means that, um, people who work on supersymmetry basically now have no particular reason to think that the particle should be at any particular mass scale. So, it, it could be there in the data or it could not be there. There are definitely people who think that it will be there, and the LHC has not, um, totally, um, analyzed all the data that they have. They're still collecting data and, um, uh, you know, getting better statistics from which they try to extract more details and so on and so forth. So, there's, there are still hope that they will find something new.

   14. CWChris Williamson32:16

       But the early evidence would suggest not?

   15. SHSabine Hossenfelder32:21

       Y- yes. I mean, so far, they haven't found anything besides Higgs.

   16. CWChris Williamson32:25

       Okay. Okay. So, moving on, I wanted to talk about dark matter or dark energy, and discuss why that's so important to physicists to find that. Could you, could you explain just why it's such an important, uh, concept within physics?

   17. SHSabine Hossenfelder32:45

       Well, let me start with saying that dark matte- matter and dark energy are totally different things. So, dark energy is whatever is causing the accelerated expansion of the universe. You know, that's just the name that we give to it. We call it dark energy. And, uh, f- personally, I think there's really nothing to explain because this, this acceleration of the universe can just be described by the constant. That thing is called the cosmological constant, and you can just go and measure it, and it has a value, and that's it.

   18. CWChris Williamson33:17

       Mm-hmm.

   19. SHSabine Hossenfelder33:18

       You know? Um, there are people who think that, um, it should have some kind of, um, microscopic explanation, you know. It should be made up of something, basically, and then there is something to explain. But I see no reason f- for why this shouldn't be so.

   20. CWChris Williamson33:34

       So, the, the line's, the line's drawn underneath dark energy as far as you're concerned?

   21. SHSabine Hossenfelder33:39

       Uh, yes, unless you sh- really show me some data that cannot be fitted with that constant.

   22. CWChris Williamson33:44

       Okay.

   23. SHSabine Hossenfelder33:45

       You know? But so far, there isn't any, and so far, the constant ju- does a good job. So then, there's the thing with dark matter. Um, dark matter is stuff, you know, basically similar to the stuff that we are made of, um, except that it does not interact with light in any form. So, it does not absorb it, it does not emit it, it doesn't scatter it. And, um, it's believed to sit around galaxies, you know, hover around them in clouds, um, and it plays a, uh, big role in the formatio- formation of structures in the universe. Uh, that's for what the simulations are concerned. Now, the problem with dark matter is that if you believe it's made up of particle, you want to actually measure the particle (laughs) , and that has not happened.

   24. CWChris Williamson34:34

       Ah.

   25. SHSabine Hossenfelder34:35

       Um, then the other option is that, uh, we actually do not need any additional stuff, but that we should change the law of gravity so that it, gravity does not work the way that Einstein envisioned it as with his theory of general relativity, you know, curvature of space-time and the rubber sheet and so on and so forth-

   26. CWChris Williamson34:54

       Mm-hmm.

   27. SHSabine Hossenfelder34:55

       ... um, about that we need a different theory for gravity, and that's what's called modified gravity. Maybe not the greatest term ever-

   28. CWChris Williamson35:02

       (laughs)

   29. SHSabine Hossenfelder35:02

       ... but that's what it's called. And, uh, ever since, uh, people came up with this idea of modified gravity, we have had two camps. The one who's the big camp, that's the particle dark matter camp, uh, and then there's the smaller camp of modified gravity, and the case still is not settled.

   30. CWChris Williamson35:19

       I see. But I'm right in thinking that if it was proven that dark matter didn't exist, if, or, I guess, I guess it's gonna be very difficult to prove that it doesn't exist because there's al- always the potential to continue, uh, detecting up until the point at which you do detect it. Is that right?
4. 45:00 – 49:46

   (laughs) Yeah. …

   1. CWChris Williamson45:00

      psychology and sociology as real sciences, and yet it would appear that those are influencing their, um, their ability to move forward, perhaps an awful lot more than they actually might think.

   2. SHSabine Hossenfelder45:16

      (laughs) Yeah.

   3. CWChris Williamson45:16

      Their, their, their cog- their cognitive biases are leading them potentially into... I think you, you describe it as cul-de-sacs in the book, where they, they almost can't get themselves out again. We've, we've touched on it a number of times throughout, throughout this, where the, uh, combination of this echo chamber and then you getting backed in by financial, uh, financial restrictions. And also, you've got this, um, uh, the weight of the existing rhetoric, the direction of this particular, this particular, um, field that you're working within and all of the social influences that you've got from people in there. It must be, um... It must be a, a difficult situation for a number of physicists who are working at the moment, who may want to make this move, or who may want to expand, uh, their body of knowledge to a different area or an alternative theory, but just feel like they can't do it.

   4. SHSabine Hossenfelder46:08

      Yes, sure. A lot of them just leave. You know, I've, I've seen people leave. Uh, I mean, it's... Uh, you see, th- these are people who figure out that, uh, they will not be able to get money to work on the research that they think is most promising, and then they just com- conclude then it's not worth their time. So, they just leave academia and do something else. And, you know, there is life outside of academia too (laughs) .

   5. CWChris Williamson46:33

      There is, but it's-

   6. SHSabine Hossenfelder46:34

      But, so-

   7. CWChris Williamson46:34

      ... it seems like a terrible shame to lose fantastic talent in the, in the field of academia because of this sort of systemic, uh, dogma.

   8. SHSabine Hossenfelder46:45

      Yes, it's a shame, but it's also just a problem for science. Because of course, uh, the people that are left are the ones who, who don't have the big problems with, uh, joining these large research programs and just producing papers. You know, if they had a large problem with it, then they would be leaving (laughs) .

   9. CWChris Williamson47:01

      Yeah, yeah, for sure. But it's not necessarily the best for the subject, this, the body of knowledge as a whole, right? People could be doing something a lot more productive if, if it was a little bit more free flowing.

   10. SHSabine Hossenfelder47:12

       Um, I, I think so. You know, this is why I hope that, uh, making some organizational changes, uh, to academic research would, um, help overcome this impasse.

   11. CWChris Williamson47:24

       For sure. For sure. So, Sabine, I really appreciate your time. Would you be able to tell the listeners where they can find you online? I'll make sure that I put a link to Lost in Math: How Beauty Leads Physics Astray, your book, in the show notes below. But where can they find you online? I really like your blog, so you need to put that in.

   12. SHSabine Hossenfelder47:43

       (laughs) Well, it's not complicated, you know? For all I know, there's only one person with my name. You type it into Google-

   13. CWChris Williamson47:49

       (laughs)

   14. SHSabine Hossenfelder47:49

       ... and, like, the first 100 hits will actually direct you to my websites. I have a website that's called sabinehossenfelder.com. It's not hard to remember if you can remember my name. Um, I have a blog that's called BackReaction, and that's at blogspot.com.

   15. CWChris Williamson48:07

       Mm-hmm.

   16. SHSabine Hossenfelder48:07

       Uh, and I'm also on Facebook, and I'm on Twitter. And I w- write for a lot of, um, websites every now and then, so you will find all this, uh, by help of Google or your search engine of choice.

   17. CWChris Williamson48:21

       (laughs) Fantastic. Sabine, I really appreciate your time. Uh, I, I hope that we've opened some people's eyes to what the physics community's like at the moment. Uh, I, I hope this doesn't sound like a, a disparaging criticism of what's going on within there. Uh, you know, it's, it's obviously a very difficult subject for, for, um, everybody to wrap their heads around, even the best minds in the world. But I do think it's so interesting what you've said about these social influences and cognitive biases influencing, uh, who we consider to be the, some of the cleverest people on the planet. And in a weird way, I think it's actually a little bit, um, it's a little bit reassuring that for us normal (laughs) , normal people who perhaps aren't, uh, aren't at the level of a theoretical physicist, that they are still subject to these, uh, these psychological and sociological influences.

   18. SHSabine Hossenfelder49:15

       Oh my God, you just found out that physicists are humans.

   19. CWChris Williamson49:19

       (laughs) Yeah, I did. And do you know what it is? Sometimes, like, sometimes I'm not sure. But, uh-

   20. SHSabine Hossenfelder49:24

       (laughs)

   21. CWChris Williamson49:24

       ... (laughs) I think I did. So, thank you very much for your time, Sabine. I'll make sure everything's in the show notes below. Thank you very much.

   22. SHSabine Hossenfelder49:31

       Uh, thank you. You're welcome.

   23. NANarrator49:35

       (instrumental music)

Episode duration: 49:46