Why the weak nuclear force is short range

One thing I'm not clear on when watching his videos is whether what he's describing is an established scientific interpretation, or his own thoughts as someone who has extensive knowledge on optical engineering (vs theory).

Very enjoyable and thought provoking stuff though!

Edit: spelling

Our present best guess is that cellular automatons would be an explosively difficult way to simulate the universe because BQP (the class of problems that can be related to simulating a quantum system for polynomial time) is probably not contained in P (the class of problems Turing machines can solve in polynomial time).

Well, Newton thought he could do it with just 3 lines, and we've all been playing code golf ever since.

Stephen Wolfram has been taking a stab at it. Researching fundamental physics via computational exploration is how I'd put it. https://www.wolframphysics.org/

Horribly complex and/or impossible.

(1) quantum mechanics means that there is not just one state/evolution of the universe. Every possible state/evolution has to be taken into account. Your model is not three-dimensional. It is (NF * NP)-dimensional. NF is the number of fields. NP is the the number of points in space time. So, you want 10 space-time points in a length direction. The universe is four-dimensional so you actually have 10000 space-time points. Now your state space is (10000 * NF)-dimensional. Good luck with that. In fact people try to do such things. I.e., lattice quantum field theory but it is tough.

(2) I am not really sure what the state of the art is but there are problems even with something simple like putting a spin 1/2 particle on a lattice. https://en.wikipedia.org/wiki/Fermion_doubling

(3) Renormalization. If you fancy getting more accuracy by making your lattice spacing smaller, various constants tend to infinity. The physically interesting stuff is the finite part of that. Calculations get progressively less accurate.

I do wonder if you'd want to implement a sort of 3D game engine that simulates the entire universe, if somehow the weird stuff quantum physics and general relativity do (like the planck limit, the lightspeed limit, discretization, the 2D holographic bound on amount of stuff in 3D volumes, the not having an actual value til measured, the not being able to know momentum and speed at the same time, the edge of observable universe, ...) will turn out to be essential optimizations of this engine that make this possible.

Many of the quantum and general relativity behaviors seem to be some kind of limits (compared to a newtonian universe where you can go arbitrarily small/big/fast/far). Except quantum computing, that one's unlocking even more computation instead...

> Could a competent software engineer, even without knowing the fundamental origins of things like particle masses or the fine-structure constant, capture all known fundamental interactions in code?

I don't think so.

In classical physics, "all" you have to do is tot up the forces on every particle and you get a differential equation that is pretty easy to numerically work with. Scale is a challenge all of its own, and of course you'd ideally need to learn about all the numerical issues you can run into. But the math behind Runge-Kutta methods isn't that advanced (really, you just need some calculus to even explain what you're doing in the first place), so that's pretty approachable to a smart high schooler.

But when you get to quantum mechanics, it's different. The forces aren't described in a way that's amenable to tot-up-all-the-forces-on-every-particle, which is why you get stuff like https://xkcd.com/1489/ (where the explainer is unable to really explain anything about the strong or weak force). As an arguably competent software engineer, my own attempts to do something like this have always resulted in my just bouncing off the math entirely. And my understanding of the math--as limited as it is--is that some things like gravity just don't work at all with the methods we have at hand to us, despite us working at it for 50 years.

By way of comparison, my understanding is that our best computational models of fundamental forces struggle to model something as complicated as an atom.

The universe is already modeled that way. Differential equations are a kind of continuous time and space version of cellular automata, where the next state at a point is determined by the infinitesimally neighboring states.

How complex? I'm no physicist nor an expert at this, but AFAIK we aren't really capable of simulating even a single electron at the quantum scale right now? Correct me if I'm wrong.

fields are a non-mechanical aether, more precisely they are lorentz invarient (ie., their motion is the same for all observers)

And if you can hop from each standing wave node to the next, you can teleport, or move ridiculously fast by moving discretely instead of continuously. What if you could tune the wavelength of these standing waves with particles stationary and vibrating?

I like the speaker on water / styrofoam particle demonstration of standing waves.

The author isn't inventing anything. He's just dumbing it down in an extreme way so that non-physicists could have the faintest hope of understanding it. Wich seems odd, because if you actually want to understand any of this you should prepare to spend two or three years in university level math classes first. The truth is that in reality all this is actually a lot more complex. In the Higgs field (or any simple scalar field for that matter) for example, there is a free parameter that we could immediately identify as "mass" in the way described in the article. But weirdly enough, this is not the mass of the Higgs boson (because of some complicated shenanigans). Even more counterintuitive, fermionic (aka matter) fields and massive bosonic fields (i.e. the W and Z bosons mentioned in the article) in the Standard Model don't have any mass term by themselves at all. They only get something that looks (and behaves) like a mass term from their coupling to the Higgs field. So it's the "stiffness" of the Higgs field (highly oversimplified) that gives rise to the "stiffness" of the other fields through complex interactions governed by symmetries. And to put it to the extreme, the physical mass you can measaure in a laboratory is something that depends on the energy scale at which you perform your experiments. So even if you did years of math and took an intro to QFT class and finally think you begin to understand all this, Renormalization Group Theory comes in kicks you back down. If you go really deep, you'll run into issues like Landau Poles and Quantum Triviality and the very nature of what perturbation theory can tell us about reality after all. In the end you will be two thirds through grad school by the time you can comfortably discuss any of this. The origin of mass is a really convoluted construct and these low-level discussions of it will always paint a tainted picture. If you want the truth, you can only trust the math.

It does have a name, it's called "coupling." A spring (to physicists all linkages are springs :-) ) couples a pair of train cars, and a coupling constant attaches massive fields to the higgs field.

He addresses this in the comments. The term that corresponds to "stiffness" normally just gets called "mass", since that is how it shows up in experiments.

Roughly put:

- A particle is a "minimum stretching" of a field.

- The "stiffness" corresponds to the energy-per-stretch-amount of the field (analogous to the stiffness of a spring).

- So the particle's mass = (minimum stretch "distance") * stiffness ~ stiffness

The author's point is that you don't need to invoke virtual particles or any quantum weirdness to make this work. All you need is the notion of stiffness, and the mass of the associated particle and the limited range of the force both drop out of the math for the same reasons.

It's nonsense. The fact that the particle is massive is a direct cause of the fact that the interactions are short ranged.

The nuance is this: Naturally, in a field theory the word "particle" is ill-defined, thus the only true statement one can make is that: the propagator/green function of the field contains poles at +-m, which sort of hints at what he means by stiffness.

As a result of this pole, any perturbations of the field have an exponential decaying effect. But the pole is the mass, by definition.

The real interesting question is why Z and W bosons are massive, which have to do with the higgs mechanism. I.e., prior to symmetry breaking the fields are massless, but by interacting with the Higgs, the vacuum expectation value of the two point function of the field changes, thus granting it a mass.

In sum, whoever wrote this is a bit confused and just doesn't have a lot of exposure to QFT

I agree this doesn't gel well with the pop-science approach.

However, it is actually a similar approach to how De Broglie, Schrodinger, and others originally came up with their equations for quantum behavior - we start with special relativity and consider how a wave _must_ behave if its properties are going to be frame-independent, and follow the math from there. That part is equation (*), and the article leads with a bit of an analogy of how we might build a fully classical implemenation of it in an experiment (strings, possibly attached to a stiff rubber sheet) so we get some everyday intuition into the equation's behavior. So from my point of view, I found it very interesting.

(What the article doesn't really get into is why certain fields might have S=0 and others not, what the intuition for the cause of that is, etc. It also presupposes you have bought into quantum field theory in the first place, and wish to consider the fundamental "wavicles" that would emerge from certain field equations, and that you aren't looking closely at the EM force or spin or any other number of things normally encountered before learning about the weak force).

In all honesty, this gives a delightful if frightening look into how physicists are thinking amongst themselves. As a (former) particle physicist myself, I can’t remember the number of times an incredulous engineer has confronted me with “the truth” about physics. But you see, for practicing physicists, the models and theories are fluid and actually up for discussion and interpretation, that’s our job after all. The problem is that the official output is declared to be immutable laws of nature, set in formulae and dogmatic conventions. That said, I agree that he is trading one possible fallacy for another here, but the beauty of the thing is that the “stiffness” explanation is invoking less assumptions than the quantum one - which physicists agree is a “good thing” (Occam’s razor).

I had very much the same feeling. Honestly this might be all true, but it's got a vibe I don't like. I did QFT in my PhD and have read plenty of good and bad science exposition, and it doesn't feel right.

I can't point at any outright mistakes, but for example I think the dismissal of the common interpretation of virtual particles in Feynman diagrams is not persuasive. If you think the prevailing view among experts is wrong then the burden of proof is high, perhaps right than you can reach in am article pitched so low, but I don't feel like reading his book.

> introducing a lot of new ideas without grounding

The grounding is 3 years of advanced math.