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Comment by gary_0 | Hacker News Reader

Electromagnetism is both a continuous wave and a discrete particle, so it makes sense to me that a continuous spacetime curvature could also be a discrete particle at the same time. (Keeping in mind we're not talking about tangible shapes but mathematical models that describe aspects of reality that are hard for humans to intuitively conceptualize.)

Of course, our idea of how to reconcile quantum gravity with general relativity is much less developed than our understanding of electromagnetism and the nuclear forces.

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My understanding is the particle model of electromagnetism, the photon, really only shows up where the em field interacts with matter(electrons really), the em field itself is not quantized, or at least not quantized at the level of the photon. Not that this really matters(intentional), we can only interact with the em field as matter so that is what matters.

> matter so that is what matters

At first I thought this was a great pun. But then this is perhaps also the reason the word is actually "matters"? Where "matters" is what means something? What matters is what has an observable effect?

The most elegant description of electromagnetism is also in terms of curvature, but the curvature of a certain mathematical structure called "connection on fiber bundles" and the math field is called differential geometry.

When you mention nuclear forces, are you referencing weak force and strong force? Do we understand these forces at the same level that we understand electromagnetism?

Yes. The Standard Model has completely explained all experiments involving them for around 50 years now.

In fact the outstanding success of the Standard Model has posed its own problems - the lack of deviations from it makes it hard for experiments to point in a useful direction for better theories to be developed along.

That's not quite accurate. There are a few things that the Standard Model doesn't exactly account for--neutrino oscillation being the most famous. The trouble is that these issues aren't really big enough to suggest new physics, and the experiments aren't good enough to really suggest how much patching actually needs to be done.

Also the unexpectedly large mass of the Higgs, which suggested (to string theorists), super symmetry. Which unfortunately turned out to not exist unless it’s at some configuration that’s quite different from what was suggested

I thought the Higgs had an unexpectedly small mass.

https://home.cern/news/news/physics/incredible-lightness-hig...

Yes, there are some deviations. But minor adjustments to the Standard Model handles those. And don't really point in the direction of a better theory.

More relevantly to the previous question, I'm not aware of any of those which affect interactions with the strong or weak nuclear forces.

Neutrinos predominantly work via the weak interaction, don't they?

> the lack of deviations from it makes it hard for experiments to point in a useful direction for better theories to be developed along.

We have anomalies (deviations from standard model) in many measurements done by several experiments. This is a good summary [1] from them up until now (sorry for the pay-walled)

[1] https://www.nature.com/articles/s42254-024-00703-6

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