Particle physicists puzzle over a new duality

https://www.quantamagazine.org/particle-physicists-puzzle-over-a-new-duality-20220801/

by kzrdude • 4 years ago

146 49 4 years ago

ISL2• 4 years ago

Very pleased to see news like this -- observations of this sort are where the big theoretical advances sometimes emerge.

jobs_throwaway• 4 years ago

Indeed, this is the sort of stupefying discovery that hints at something deeper

cwillu2• 4 years ago

“For Dixon, this is a tiny hint at a deeper physical connection between the two amplitudes, and a reason to think something similar might hold in the Standard Model. “But it’s pretty weak,” he said. “It’s, like, secondhand information.””

This appears to be a development in a toy model. It might or might not apply to the standard model.

Still, at least it isn't a condensed matter experiment being misconstrued as a particle physics breakthrough.

phkahler• 4 years ago

> misconstrued as a particle physics breakthrough

Hey don't throw shade on quasiparticles, they're people too.

cwillu2• 4 years ago

“I identify as Higgs”

zmgsabst5• 4 years ago

When does a quasiparticle become “particle physics”?

As far as I can tell, protons and neutrons are quark-gluon quasiparticles, but we’re happy to call studying protons and neutrons “particle physics”.

From Wiki:

complicated system such as a solid behaves as if it contained different weakly interacting particles in vacuum

That is, this description fits protons and neutrons relative to quarks and gluons: very cold quark-gluon regions behave as if protons and neutrons exist.

https://en.wikipedia.org/wiki/Quasiparticle

joe__f8• 4 years ago

I finished up my PhD in scattering amplitudes recently. I checked out the abstract of this paper, and it certainly looks like an interesting result and will likely be the basis for new results in the field. For perspective, I estimate that there are a few such results in the field per year which could have roughly the same quanta magazine article written about them.

mmazing3• 4 years ago

Any guesses what this could stem from?

joe__f8• 4 years ago

I think it's a bit of a feature of quanta magazine's approach to science journalism (and probably the current zeitgeist in science journalism in general). If you want to make work like this accessible then it's necessary for a large portion of the (pop science) article to be covering topics that are common to most of the recent work in the field, with a lot of the same analogies and motivations. I think it's nice that quanta magazine are trying to make this kind of work accessible and interesting for people, but I feel that their approach sacrifices perspective on how relevant that work is, which is why I tried to add some here.

Rebirth-0822• 4 years ago

Hey, I know that this is probably too broad a question, but I'm curious: what kind of mathematics did you require to do your doctorate? I'm curious as to what I'd need to (re)-learn to truly understand this.

analog31• 4 years ago

You didn't ask me, but I can shed some light, having earned a physics PhD in the early 90s, after doing an undergrad double major in math and physics.

The undergrad physics curriculum includes the standard college sequence of calculus and differential equations. Many physics students take more math than this, or today, probably some computer science. We took a "physics" course called "theoretical physics" that filled some gaps in the math sequence, most notably multivariate calculus in cylindrical and spherical coordinates, path integrals, and some stuff like that. Specific upper level physics courses also introduced math topics as needed.

Graduate coursework re-iterated the same "theoretical physics" course, but it was called "mathematical methods." We used a textbook by Arfken, that covered the same multivariate calculus plus vector and tensor math. Finding out what the current textbook du jour is for this course, and perusing the table of contents, would give you a pretty good idea of what to expect.

I didn't go into scattering theory as a specialty, but we covered it in some of the other courses, and I remember doing difficult integrals and differential equations in spherical polar coordinates. The coursework quickly runs you out of problems that can be solved in closed form. I'd be shocked if the real work isn't done today with mostly numerical techniques.

MengerSponge• 4 years ago

https://webspace.science.uu.nl/~gadda001/goodtheorist/index....

You need to work up to (and through) Quantum Field Theory to understand this.

Thankfully, you don't need to be as good or as thorough as Gerard 't Hooft as you learn all those things!

joe__f8• 4 years ago

Scattering Amplitudes in Gauge Theory and Gravity by Elvang and Huang is a standard introduction to the field, if you wanted to take a look and see what you might need to learn to get up to scratch. There are a lot of prerequisites.

nottim• 4 years ago

The first sentence of the abstract is a helluva mouthful: "We observe that the three-gluon form factor of the chiral part of the stress-tensor multiplet in planar N = 4 super-Yang-Mills theory is dual to the six-gluon MHV amplitude on its parity preserving surface."

For any of you paper-writers out there, some advice: the abstract shouldn't contain undefined acronyms, and should be readable by anyone who you would expect to be at a conference where you present your paper. Exchanging a bit of the technical correctness for readability is the entire point of the abstract, and the source paper's abstract could really use some work.

ISL2• 4 years ago

That sentence is very readable for anyone who would be at a relevant conference.

As an experimental physicist, everything but the MHV (maximally helicity violating) was readable/comprehensible to me. Theorists in the field will read that as easily as breathing.

sebastialonso• 4 years ago

Context is king. It's the abstract of a paper, not simple Wikipedia. Everyone reading the paper itself is expected to either know or make the effort the become knowledgeable enough to understand. In any other context, I'd agree but we're taking about a paper on theoretical physics on a potential new interaction lol

galaxyLogic• 4 years ago

I think this would be a great task (and challenge) for AI: Make abstracts understandable to a wider audience.

mannykannot2• 4 years ago

I take it as a sign that I would have to understand a bunch of prerequisites before I could understand the content of this paper, its implications, and the possibilities it raises.

maxnoe• 4 years ago

It's a paper, not an introductory textbook...

prof-dr-ir• 4 years ago

Do you maybe have a concrete suggestion for how you would rewrite it? Which parts do you think are not understandable for anyone attending, say, the annual Strings conference?

civilized• 4 years ago

In a field like this, the abstract is more about conciseness than accessibility. It's for a fellow specialist skimming through dozens of papers looking for something interesting.

jarenmf• 4 years ago

Every writing course I attended in grad school told us that the first sentence of the abstract should be understandable by any scientist, the second sentence should be comprehensible to a scientist in a related field. After that, you address the specialists community. However, it seems that more and more people are skipping the first and second sentences and jumping directly to talking to specialists. I have mixed feelings about that. On one hand, it's nice to skip the generalities but at the same time some times its nice to have some context.

raverbashing• 4 years ago

and should be readable by anyone who you would expect to be at a conference where you present your paper.

Yes, I guess this is pretty much the case here. There's no much way to simplify this

Conciseness is important in abstracts and it beats general simplifications.

joe__f8• 4 years ago

I have a PhD in this field. I understood everything in the title straight off, apart from the context of which 'parity preserving surface' they were talking about (which was fine). I think this was a concise and well-written abstract, which was easily readable within the target audience. There are very many different concepts that you have to build on and learn to be able to write something like this paper. It's unfortunate that abstracts in the field are not more accessible to a wider range of people, but I don't see an easy solution to that. If you went to the yearly conference on this field and started asking people to define 'MHV' in their abstracts I don't think you'd get many converts. This acronym is cryptic, unintuitive and completely ubiquitous and ingrained in the literature.

coliveira• 4 years ago

They're not writing for you.

ChrisLomont• 4 years ago

The abstract looks perfectly fine - it is written so anyone working in this area would know what the paper is going to do. Writing it at a basic level would either require the abstract to be absurdly long or to leave unspecified what the paper contains.

I'm not in particle physics, but have read textbooks and papers in many areas of theoretical physics, and I understand enough of this abstract to know what it's going to do.

If MHV is an acronym you think should be expanded, it is not. There's well over 500,000 hits on google for MHV physics, and only 2900 hits for the expanded term. It is a widely used term in the field.

gfodor2• 4 years ago

Can a physicist comment on the impact of this to the work by Nima Arkani-Hamed et al on the Amplituhedron (https://en.wikipedia.org/wiki/Amplituhedron)?

joe__f8• 4 years ago

Great question! This result is in the same area as the work on the amplituhedron. It's not immediately obvious to me that they are directly related, and I didn't see a reference to any amplituhedron papers in the citations of this paper. Dixon et al. have essentially discovered a new symmetry which the scattering amplitudes (of N=4 Super Yang-Mills) must obey, and new symmetries generally lead to deeper understanding of the theory. This symmetry should then also be somehow encoded in the amplituhedron description of the theory; I imagine people would look into this in the future.

gfodor2• 4 years ago

Cool, thanks!

legohead• 4 years ago

As a complete layman to all this, after reading the article it feels like more proof we are in a simulation.

uoaei• 4 years ago

No one said the computer running the simulation used digital logic. If we could encode system dynamics into "energy+matter", you could call it an analog computer without much dissent. People do this in miniature: in fact, the first computers were entirely mechanical!

If we accept this reasoning to imply that the universe is a giant computer, we only have the unknowable left: was it purposefully (intelligently) designed or did it spontaneously arise? As far as I can tell, the probability of either outcome is equal according to our limited experiences, and we will never have access to a definitive answer one way or the other.

Particle physicists puzzle over a new duality

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