Faster Than Light in Our Model of Physics: Some Preliminary Thoughts

Not convinced that's true. Considering how many physicists still keep talking about String Theory, even though it hasn't produced a single testable prediction after 30+ years.

He is not presenting this as a scientific theory. This is a keynote speech for NASA folks. Just like science fiction is not science, it may still inspire scientists and be worth listening to IMHO.

>"To prove that 110 is NP-complete, what is needed is to show that Rule 110 allows efficient simulation of Turing machines"

But if the universe is a 'computation', then the efficiency of it doesn't really matter right?

Similar to creating a Blender rendering, it doesn't matter how long each frame takes to render compared to any other frame, as long as the observer sees a smooth sequence of images.

I say the future generations will be better off for Wolfram having gone down his rabbit holes.

This model does not purport (in its current iteration) to explain material reality. It purports to generate a theory of physics without going so far as to claim that that theory coincides with the dynamics of our universe specifically.

It is taking the idea of "physical model" and abstracting it to see how flexible of a theoretical substrate can be used to demonstrate certain behaviors within the defined set of axioms which we would expect out of any model of physics, i.e., causality, limits of information propagation rates, etc.

In short: it is not a theory of the physics, but just a physics.

Since when this is redefinition? As far as I understand, this was always the definition. In fact, calling it the speed of light was always a bit misleading, since, first off, actual speed of light depends on environment, and second, there is nothing really special about light. It's just under ideal circumstances it can propagate with the maximum possible speed, i.e. the speed of causality. Light isn't fundamental for the laws of physics, causality is.

What Wolfram has to do is to replicate known physics at a minimum and ideally derive new testable predictions that we can attempt to falsify.

If he does that his unproven priors will become the new "taken for granted" priors.

What's the mainstream theory for what reality actually is?

The goal is to model the real world, but it's far too difficult to go straight from a fundamental model up to the world observations to find out if the model works.

Doing that "work out the consequences" work can take decades, and a lot of people.

So models are built, explored, their consequences worked out, and if they match something interesting in other more well-established theories, then the models are looked at with more interest and developed further. If not, the models are tweaked or thrown away.

You could call it a branch of mathematics, but in a sense all theoretical physics starts out that way, so we just call it theoretical physics when the goal is to model observed reality while providing a useful underlying model.

Browse the papers on arXiv.org or any theoretical physics journal and there's a lot of exploratory model-building like this. It's very common.

Graph-space models are also not unique to Stephen Wolfram. Several physicists (paid ones) are exploring these models as an approach to reconciling relativity and quantum physics. In a sense, this is what deriving from observation looks like: We've observed relativity and quantum, and we still haven't figured out how to understand the logical consequences of both together, so exploring theoretical underlying models like this is necessary to understand current observations.

The article's theory is not "philosophical" or "metaphysical" theory where nothing can be tested in principle. He explicitly talks about measurable effects differing from other models, albeit with many difficulties and potential intractibility due to computational limits.

But the point is there are, in principle, observable differences, making it more than just a metaphysical model, and if it's intractable to access them we can't figure that out without studying the model further. Even if we can't, there not being able to may have consequences as well (like the way the Heisenberg uncertainty principle turns out to have logical consequences, not just preventing measurements).

How does the special molecule move? By magic? By willpower? By an internal combustion engine?

It needs some way of changing its course. Molecules don't have such a mechanism, except for bouncing off of other molecules.

And, how does the molecule know where the other molecules are? It's psychic? Lidar? Radar? How? What's it's energy source for emitting whatever it has to emit to be able to gather the information that it needs?

The analogy is, if we take a superficial knowledge of physics, and don't actually think about the details, we can construct a wonderful-sounding-but-not-actually-possible scenario. That's perhaps an accurate analogy for what Wolfram is really proposing.

Actually Stephen's special molecule is more powerful because it's omniscient. Ordinary Maxwell's demons just see fast or slow molecules coming at the gate and act accordingly. This one knows the momentum and position of every other particle it needs to know something about, which can be peculiar if you don't think about uncertainty.

I thought the point of the gas illustration was to show how the assumption there's an information problem (i.e. heat, second law) is actually not correct.

That it only looks like an information problem and it's really a computation problem.

The theory being that if you can compute were the molecules are going to be, from the initial state or from interactions you have already learned from, then the motions don't appear random any more. There are no surprises; you have "decrypted" the apparently random movements.

It's just to illustrate the idea, and an immediate objection would be "but we can't know everything to that much detail".

That is addressed by a more subtle version of the argument, which says: Although you don't know all the motions precisely, your ability to compute motions from the information you obtained so far gives you progressively increasing knowledge about motions locally or which you recognise as related, and causes "regions of effective coherence" to expand. It's effective coherence not actual coherence, because the molecule motions don't change, only the precision with which you can anticipate some of them as well as relationships between them. What would have appeared random, now with the benefit of some prior information and computation resolves gradually into local clusters of more predictable related motions, even if you don't know every motion accurately. With the result that the effective fluid properties change, so your ability to "swim" through the gas changes.

In the 2d closed box model, with perfect balls and perfect interactions (i.e. a mathematically perfect simulation) it's plausible that this may work perfectly. That is, if you have your own "special" ball and it undergoes a number of collisions and you get perfect measurement of those collisions, eventually you end up with enough information to model the contents of the rest of the box. If in that model you can dynamically adjust something about the collisions of your "special" ball, for example changing the ball's shape, mass or radius, it's plausible that can be used to travel anywhere in the box much faster than diffusion, but only if you have the information up to that point and excellent computation - which might be irreducibly hard computation for a reasonably sized box.

Yes it does. This is a basic consequence of the underlying pseudo-Riemannian geometry. In terms of PDEs, the field value at any point is fully determined by the initial conditions on a Cauchy surface within its past light cone.

Quantum mechanically, field operators at spacelike-separated points commute.

> Also, it seems pretty clear that Wolfram does not understand the concept of Warp drive, which is not used to propel the craft, but instead used to warp space to come to the craft

You didn’t read the article. This is addressed at the end, under “What about warp bubbles and the Alcubierre metric?”.

It also seems that this concept is very generic, and many properties of the model do not depend on the dimensionality neither on the manifold or the rule itself.

Because this concept is so generic, one hopes that there is a rule that the hypergraph converges to d=3 as in our world. This would also raise questions on why in the very early universe there was a "inflationary" phase.

[0] https://www.wolframphysics.org/technical-introduction/limiti...

And while that is possible, the trade-offs are usually far worse or harder to explain than the baggage QM brings. Or just based on an incorrect understanding of QM

Here is one breakdown: https://arxiv.org/pdf/quant-ph/0206089.pdf

Lorentz and other physicists had already derived a set of equations(called Lorentz transformations) that must be true given the experimental failure. But they considered it unthinkable that the speed of light could be constant in all inertial reference frames, so they thought those equations were wrong or that there was something they were missing.

The only thing Einstein did in that situation was come in and say "hey what if that unthinkable thing were actually true?"

Contrast this with Wolfram's article, where he's postulating the existence of an entire kind of physics without any experimental or phenomenological basis. The comparison is without any basis.