Physicists are fighting over 'Cotton gravity'

The halls of science, known for prim propriety and careful debate, are feuding. A new theory of gravity challenges Einstein's general relativity, our current understanding of that thing that keeps our feet on the ground. Physicists are upset.

"Cotton gravity"—named in honor of mathematician Émile Cotton, not fluffy flora—was first posited by Japanese researcher Junpei Harada in 2021. The idea, which modifies general relativity and discounts the theory of dark matter, spurred a surprisingly catty argument on arXiv.org, an open-access website for scientific preprints.

Things got nerdy. And hilarious. Endless Thread explains.

Show notes:

This content was originally created for audio. The transcript has been edited from our original script for clarity. Heads up that some elements (i.e. music, sound effects, tone) are harder to translate to text.

Ben Brock Johnson: Dean, in classic form, this episode started with me sending you a Reddit post and saying, Could you make something out of this?

[@aerithgirl: The physics girlies are beefing. Specifically, theoretical physicists who are literally at the forefront of their field. Academic beef is so funny.]

Ben: And then you ignoring me for a period of time.

Dean Russell: Pretty sure I was on vacation. I'm pretty sure I was on vacation. And you sent me this video...

Ben: You still ignored me, though. I'm just kidding.

Dean: ...and I was standing there with my wife, and I was looking at this video, and she was like, Why did Ben send this to you? And I watched the whole thing, and then at the end, I was just like, I think it's because I'm a nerd.

Ben: Yeah, I think that's right. I think that's right.

Dean: Well, here I am. I looked into it. And so, for this here Endless Thread, from WBUR, Boston's NPR, the hot place for goss in the science and TikTok world, I bring you a short, snacky story we'll call "Nerd Fight."

Ben: Nerd fight! That's what we yell, right? When the nerd fight is happening? Nerd fight!

Dean: The Halls of Science, Ben. The Halls of Science, places for prim propriety and careful consideration, are witnessing a very public and dramatic feud.

Dr. Blitz: It's almost like watching a slapfight between a bunch of nerds.

Dean: Ben, meet Dr. Blitz, a physics PhD with about 250,000 TikTok followers. One of them is me.

[@blitzphd: On this platform and on others, I. I go by blitz with PhD doctor blitz because I have a PhD in physics.]

Ben: All right, Dr. Blitz.

Dean: People who follow Dr. Blitz are interested in things such as...

Blitz: Differential geometry.

Blitz: String theory manifolds.

Blitz: Toy models of quantum gravity.

Blitz: Black hole event horizons.

Blitz: Things that have no bearing on anything to do with the real world. 

Ben: Is he saying string theory isn't real, man? Is that what he's saying?

Dean: Nothing that would affect your day to day life. I think that's what he's trying to say. Dr. Blitz is the reason that anyone without a PhD, including you and me, knows about this story. He brought it to TikTok. This is the story of a feud that began a few years ago.

Blitz: Had nothing to do in my office. I was looking at these papers that just popped up on my feed.

Dean: Dr. Blitz was looking around on the internet at a feed that is not TikTok or X or whatever. It's a special nerd feed called arXiv.

Ben: Oh, yeah. Is it archive.net? No.

Dean: ArXiv.org. A-R-X-I-V.

Ben: Yeah, yeah, yeah.

Dean: So, for the uninitiated, arXiv is a digital feed for scientific preprints, like papers awaiting publication in academic journals. And because they are preprints, they are also not peer-reviewed, which means they can get a little wild.

So, Dr. Blitz is scrolling. He sees this paper about a new theory called "Cotton gravity."

Blitz: ...and it's hard to go into the details of this without actually going into the details.

Dean: Do you have any idea what Cotton gravity is?

Ben: Gravity that's kind of fluffy and feels pretty good against your skin.

Dean: That's what caught my interest, I have to admit. There's a disappointing answer to this, but it caught my interest.

Ben: Perfect.

Dean: That is not to say that Cotton Gravity isn't super cool. I mean, for all the science nerds and the factoid nerds, there's plenty to get into here. Even if you don't care about nerd fights. Which, how could you not? But anyway, first, context. We gotta know the context. So, our current understanding of gravity, like what is gravity, was described by?

Ben: Sir Isaac Newton? Apple — there's an apple that falls on his head.

Dean: That was the case until about 1915, and then it was Einstein with general relativity.

Ben: Yeah, general relativity. Fine.

Dean: So, Einstein's theory says that gravity is not a force; it is a curved field.

Blitz: I'm sure people have seen this rubber sheet analogy. It's not a great analogy, but it'll do. You put the apple on the rubber sheet, and it bends down a little bit.

Ben: I've seen these videos on the internet. It's great. Yeah, and then you roll the balls around and their behavior changes as they come close to the large object that has gravity, and the gravitational field is changing the way that they behave. Yeah, I know what you're talking about.

Dean: Yeah, For anyone who hasn't seen any of those videos, that did it for you, I'm sure. I'm sure you see it now.

Ben: Everybody's seen these. Come on! Everybody!

Dean: There are, you know, some things that Einstein couldn't explain, though. For instance, galaxies rotate faster than his theory predicts, so scientists think there —

Ben: I think he probably forgot to carry the one, don't you think? I think he forgot to carry the one.

Dean: Well, the version of forgetting to carry the one is forgetting to take into account some invisible thing there that we now call...

Ben: Dark matter.

Blitz: We can't see it, we don't know what it is, but it's this thing that unless you put it into the theory, then it doesn't make sense.

Ben: I wish I could do that in my life. You know, if I'm just wrong about something, just be like, yeah, it's the dark matter. It's the dark matter. It makes sense if you put the dark matter in, no problem.

Dean: So, it's kind of funny because dark matter started out as this kind of wild guess, hypothetical workaround. But the more scientists have looked into it, the more evidence they find to support dark matter. That said, for some scientists, dark matter still feels like blaming a drowning on the Loch Ness monster. They think there may be a simpler explanation.

Blitz: So people try to come up with new theories of gravity that are very similar to Einstein's theory of gravity but change it in a certain way.

Dean: Cotton gravity is one of those new theories. Has nothing to do with the fluffiness. It was named for the mathematician Émile Cotton, who died in 1950.

Ben: Okay.

Dean: Cotton gravity may explain the universe, depending on who you ask. And it also says that dark matter probably doesn't exist.

Ben: Wow, shots fired!

Dean: But, Ben, this one fluffy idea collapsed into a black hole of debate. We will get to the heavy science drama in just a minute.

[SPONSOR BREAK]

Dean: Ben. Here we are, looking at the drama that unfolded over a little idea that may or may not disprove dark matter. Probably not. But anyway. This idea called Cotton gravity. Now, our TikTok guide, Dr. Blitz, was following this story from the get-go. He was reading along as the first papers were coming out about Cotton gravity in 2021, 2022, initially by a researcher named Junpei Harada. Dr. Blitz watched more researchers, though, jump onto the bandwagon. And people were getting excited about Cotton gravity.

Until December 2023, just a few months ago.

Blitz: You have these two people, Clément and Nouicer, I think they're French, they write a paper called "Cotton gravity is not predictive."

Dean: These two French physicists write a response to cotton gravity. The gist is that it's all a waste of time, and these two physicists, who I will call the Dark Matter Duo, explain why Cotton gravity sucks, saying things like...

[@blitzphd: You can't make predictions using it, so it's useless.] 

Ben: Yeah, "not predictive" is like, I feel like that's like the physicist's version of a deep insult.

Dean: For anyone interested in the details, I'm sorry, I won't even try to explain them. They're like...

Ben: Heh heh heh.

Dean: ...beyond my ken and then some. But, anyway, after about a couple of weeks...

Blitz: Three weeks later, January 19th.

Dean: ...four scientists...

Blitz: Sussman, Mantica, Molinari, and Nájara.

Dean: ...who I will call the Cotton Quartet — they are very pro-Cotton gravity — they write a response to the Dark Matter Duo's response to the Cotton gravity paper.

Ben: Heh heh heh.

Blitz: I don't want to assume anything because sometimes science just gets this way. But it seems like these are not people that like each other very much. 

Dean: Now, Ben, you may skim this paper, and you would be like, meh, whatever. But, there are these little phrases sprinkled throughout that speak to scientific mean-girlism. For instance, the Cotton Quartet says that the Duo's claims are, quote, "completely mistaken"...

Blitz: I could never imagine saying to somebody else that I don't know particularly well, You are "completely mistaken," you know nothing about — I just can't imagine saying that. 

Dean: ...and that this paper, the Cotton Quartet's paper, quote, "explains the confusion and errors" in the Dark Matter Duo's work. Or, as Dr. Blitz said on TikTok:

[@blitzphd: That's the physics equivalent of calling someone an idiot.]

Ben: This is heavy stuff.

Dean: Not long after the response to the response comes a response to the response to the response.

Ben: Oh no.

Dean: The Dark Matter Duo, who hate Cotton gravity, they write a paper called "Farewell to Cotton gravity."

[@blitzphd: In the very first paragraph, they accused the four authors of basically not reading the original critique. And then they proceed to say, "while this should be obvious, we feel it is necessary to reformulate and expand our argument in this short note." Like, what?]

Ben: Wow.

Blitz: I literally gasped when I read that, and I wasn't being hyperbolic. I'm like, You can't just say, "This should be obvious," but apparently we have to explain it to you. That's taking it pretty far.

Dean: So in this paper, the duo also says, quote, "let us correct several erroneous statements," and quote, "actually, we did mention" that.

Ben: This has now turned into an all-out physicist spat.

Dean: Then, a few weeks ago, one more paper comes out. This is, to get us all on the same page here, this is the response to the response to the response to the response. It was written by the Cotton Quartet, so the people who are pro-Cotton. And in it, they do admit to making a mistake.

[@blitzphd: But the next sentence, they write, "However, every single other argument we expressed in our criticism of their original submission remains valid and has not been addressed nor disproved by Clément and Nouicer."]

Dean: They also say that this will be their last response.

Blitz: I guess they were getting sick of it, which is fair because it was getting pretty messy.

Dean: Ben, I reached out to the Cotton Quartet and Dark Matter Duo. The Quartet sounded very excited to talk about this, almost like no one has ever reached out to them ever to talk about this. But then they never responded to my response.

Ben: Oh, that's very out of character for them, I feel.

Dean: The Duo, however, politely declined, and they said that they only wrote those papers to, quote, "alert young researchers against going on a wild goose chase."

Ben: Oh. Also very spicy for physicists.

Dean: Very spicy. They said they "never intended that this debate should go public."

Ben: So, Cotton gravity, is it a thing or not? Where have we landed here?

Dean: I asked, Dr. Blitz about this because I could definitely not answer that question for you, even remotely. And he said, you know, the jury's out. It's probably a safer bet to just go with Einstein, which kind of makes sense. But, who knows? You know?

I think what drew me into this, what drew me in is, you know, the annals of science are full of feuds. Newton, his most famous quote is actually just like a backwards way of calling Robert Hooke short. "If I have seen further, it is by standing on the shoulders of giants" — that quote is just a way of being snarky.

Ben: Wow.

Dean: Edison called Westinghouse and Tesla's invention deadly, and then he, he used it to execute an inmate to prove his point.

Ben: Wow.

Dean: And then, you know, there are a bunch of others. The Bone Wars, Darwin vs. Creationism, on and on. I asked Dr. Blitz what he makes of the history, this sort of snarky tradition. Does he think that scientific rivalries are for the better or for the worse?

Blitz: It's tricky, right? Because on the one hand, you don't want a hundred different theories of gravity and everybody's like, Yeah, they're all right. You don't want that. On the other hand, you don't want to turn people off from working on really neat ideas, even if they're initially wrong, because if they had stopped working on it, then we would never know. 

Ben: The thing that strikes me about this story, is that I think of scientists as incredibly sportsmanlike, right? They are people who, you know, fundamentally, one of the things that you have to accept as a scientist is that the work you do will always be cross-examined and checked and maybe disproven at some later date, right? So, one of the things that I experience in talking to scientists, as I'm sure you do as well, is it's actually pretty hard to pin scientists down on just pure statement of fact when it comes to the work that they do, right? They will always say something like, "All of the evidence suggests," or "I've never seen anything that disproves this," which fundamentally that's a hedge, right? You're not like, "Peanut butter is made from peanuts." You're like, "In the entire history of the world, what we have seen is from the data that we have collected is that all forms of peanut butter that we know to exist in the world have been created from peanuts." So, I guess the thing that strikes me here is that even with that kind of forced openness to others' ideas and others' evidence, there's still some sick burns that get thrown around.

Dean: Yeah.

Ben: So like, what is the next development in this story, do you think, Dean?

Dean: The mic has been dropped. I think if some discovery is made or something like that, then maybe we'll all be talking about Cotton gravity. But for the time being, I think it's general relativity all the way. Still, this stood out to me as a remarkable story simply because it's a reminder that even the best ideas in science, the ones that we consider unassailable, like general relativity, they are always being poked and prodded and debated and tested. Sometimes, those debates get a little catty, and that's why this one popped up. But the more important takeaway is that science is a process that never stops. It's never satisfied. Because we're never satisfied. We are human because we have to know how it all works, and we won't settle for the first solution we dream up. And when we do reach an idea and test it and test it and test it and get the same results, then we can feel good about those ideas. We can build our world around them, while also making room for the slight chance that a new idea will come along and shake everything up again.

Ben: Alright. Well. Dean, thank you for this thorough exploration of what seems to have amounted to an insult rap battle among physicists. It's been very enjoyable. Nerd fight!

Dean: Endless Thread is a production of WBUR in Boston. This episode was produced by me, Dean Russell, and the show is hosted by Ben Brock Johnson and Amory Sivertson... who is still coming out with her investigative series Beyond All Repair. Check it out. It's pretty good.

Mix and sound design by sound nerd Emily Jankowski.

The rest of our team is Katelyn Harrop, Samata Joshi, Frannie Monahan, Matt Reed, Grace Tatter, and Paul Vaitkus.

Special thanks to Dr. Blitz and aerithgirl on TikTok.

Endless Thread is a show about the blurred lines between online communities and the touch, the feel of space-time. The literal fabric of our lives.

If you have a nerdy online fight story that you want us to tell, email Endless Thread at WBUR.org. We will respond. And then you can respond to our response. And so on and so forth. Bye.