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Comment by stared | Hacker News Reader

Well, it feels shaky. First, it starts with:

> There is a growing consensus in theoretical physics that spacetime is not a primitive notion

That’s a very strong statement. I’m not sure what the actual distribution of views on spacetime is, but there certainly isn’t a consensus on that matter. If I wanted to establish credibility, I wouldn’t open a paper with such a dubious claim.

Second, Pauli matrices are highly relevant to space (see: Dirac spinors; but also, they can be used for quaternions—i.e., rotations in 3D). Using Pauli matrices to argue that we live in a 1+3 spacetime feels, at the very least, like a circular argument.

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The idea that spacetime is emergent and not fundamental dates back to the 60s and has seen some pretty neat stuff along the way, like Bekenstein and Hawking discussing information problems in the 70s that hinted at a deep connection between gravity and thermodynamics. Then in the 90s we had Jacobson deriving General Relativity from the first law of thermodynamics and in the 2000s we had Verlinde combining this with holography. It's not a "solved" problem by any stretch, but some of the greatest physicists of their generation have meddled with this and I think there are almost none left who would refute the basic idea. It's the details that people are still arguing about - which now include this paper.

There are quite a few ideas! Myself, I would bet on Polymarket that there is something more fundamental than curved 1+3 spacetime.

Some are, as you said, in thermodynamics. In the String Theory, 1+3 is a somewhat reduced space from original 26 dimensions or so. (This "somewhat" is the core issue.)

So sure, "The idea that spacetime is emergent and not fundamental dates back to the 60s" would work as an awesome opening of the paper.

The "growing consensus" bit literally alludes to all these developments. But granted, you have to be versed in the field to understand this. On the other hand, this is a research paper. It is not written for laypeople.

I don’t think anything is fundamental given that there is always something that is made of that something.

"Growing consensus" is not the same thing as consensus. If currently 20% of the top physicists think spacetime is not a primitive notion and this number has monotonically increased by 1% every year for the past decade, that would be an example of "growing consensus".

Besides, Vlatko Vedral is a top theorist in the area, who talks other top theorists at conferences and workshops. He wouldn't say this if he didn't think other top theorists didn't agree with him.

Weasel words (or other common sense statements said passed as objective truths) should not be a part a scientific paper, regardless of who is writing that (yes, I know that Vlatko Vedral is an established researcher).

Myself, I am quantum physicist by training. While I have certain views on stuff (e.g. many-world interpretation and decoherence, in the line of ZH Zurek), I actually cite surveys on the view on physicist on QM interpretation. (Even though I "know" from my personal observations that all almost all theoretical physicists are in the MWI.)

> If currently 20% of the top physicists think spacetime is not a primitive notion and this number has monotonically increased by 1% every year for the past decade, that would be an example of "growing consensus".

Awesome! Then any reference with such data would be useful. If one cannot make (or even create a personal survey), then one should not write such things as facts.

No this has been a talking point by top spacetime theorists for a very long time. E.g. https://www.cornell.edu/video/nima-arkani-hamed-spacetime-is...

I don't think the Pauli matrices are used per se I think they are derived from the anti-commutation criteria of the basis elements. I don't know what justifies that criteria though.

ianap

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