Gregor

YouTube video by SAGEX Network Spacetime, Quantum Mechanics and Scattering Amplitudes - Nima Arkani-Hamed

If we forbid ourselves from talking about the bulk interacting theory and only look at the asymptotic S-matrix, the first-order answer is that they're in the poles and resonances of amplitudes and the compositional relations between them. Really can't recommend Nima's talks enough for this pov!

yeah

It is a bottomless sea, but we do not have to worry about that. The picture of a bottomless sea is not so disturhing really . We just have to think of the situation near the surface,

advice from Dirac for whoever needs it

The reason quark masses make sense is bc of asymptotic freedom. The tale I heard is there used to be a big debate about whether quarks are real or not and at some point 't Hooft said sth like "what matters is only whether they're a *useful* description", then everyone started pretending they're real

But the quarks etc don't globally show up as Wigner irreps! the irrep decomposition is objective but finding it essentially involves solving the dynamics so it's a bit cheating really. Quarks just really look like irreps at small distances

From what I can tell there is no objective way to distinguish a bound state from a fundamental particle when the mass is discrete, I think it's just convention

They must contain the same Wigner irreps, since there is an equivariant map, right? But this doesn't tell you anything about bound states and infraparticles, which are in the continuous part of the mass spectrum. I'm pretty sure these are encoded only in S itself

might *NOT even have protons

If you only know about the true asymptotic S-matrix, maybe you will ask what the hell is 'strong force' in the first place? From this perspective I think it too is essentially nothing more than a factorization structure of the S-matrix

It's just that we imagine a separation of scales wherein the S-matrix in some sense factors into parts which are relevant to different scales, and at a scale where the strong force is weakly coupled, you can talk about a QCD S-matrix

very strictly speaking you might have protons I guess? Likely everything decays to like neutrons, electrons and neutrinos plus spread-out massless fields for the asymptotic states of the 'true' S-matrix if such a thing ultimately makes sense.

this is what we have the renormalization group for
Goku is just at a critical point

Physicists of Bluesky! I'm looking for a specific type of story from the early days of cyclotron research, for a piece for @physicstoday.bsky.social . Have you heard tales of scientists who aligned beams with the naked eye? Know an older physicists who has? Let me know!

would at least explain why we're not Boltzmann brains, though!

the SpaceTime ship

for those unaware, this feed is extremely cool & useful & good!

me dropping 'I think' into every math/phys thing I say on here
(I don't like the hedges but they're necessary in some form or other, one does want to communicate abt things one hasn't yet understood 100%—which includes every interesting thing—, and then one has to signal a rough level of confidence)

hmmm

I'm very sympathetic to 'qualia are incoherent', what tickled me was 'The reason I think qualia are incoherent is because I have nonstandard qualia' haha
but I get what you mean I think

I tend to feel similarly about concepts embedded in the language around consciousness. But just pragmatically.. you being objectively different from most people in some aspect concerning the perception of qualia kind of necessitates there is a thing to be talked about, you just disagree what it is

you have a nonstandard experience of the incoherent thing?

Soon you might be able to do all of it in a pleasant (albeit more difficult) fashion :^)

it's bc you've sheafified. congrats on gluing ur sections youre global now

ig the main point is there are very nontrivial maps between n-truncated and k-connected types when k>n in general (whence group cohomology)

One should still be able to get additive cohomology H^k(G,K), though. Take K[S^(k-1)] for the k-VS (so it's also nontrivial in deg 0). So I still think it's nontrivial for 1-groups and doesn't reduce to min(n,k), though maybe it's 'uninteresting' if ordinary group cohomology is boring..

idk, does a chain complex in deg k 'want' to be in deg 0?
But I was mistaken above I think—the gerbe thing is true for some notions of k-vector spaces (see nlab page for Brauer gp), but probably not for this one *unless* k=1 (irrespective of n), which is what misled me lol

There's a (B^k K*) in the core groupoid of k-Vect basically

Hmm I think then I was right and any group cohomology class in H^k(G,K*) 'is' a k-rep (where the image of the functor is a k-VS zero in degrees < k-1 and 1d in degree k-1).

I'm not sure I know what a k-vector space is generally, but I'm pretty sure the ⓧ-invertible 2-reps are supposed to be gerbes, i.e. classified by a Brauer group, right? That's definitely not uninteresting for n=1,k=2 (or higher k and higher gerbes).

better go the distance and ask an ω-question, a recursive infinite tower of questions-about-questions-