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James Webb Space Telescope finds evidence for alternate theory of gravity

(thedebrief.org)
355 points jchanimal | 2 comments | 16 Nov 24 18:33 UTC | HN request time: 0.416s | source
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samsartor ◴[16 Nov 24 20:21 UTC] No.42158987[source]▶
My hangup with MOND is still general relativity. We know for a fact that gravity is _not_ Newtonian, that the inverse square law does not hold. Any model of gravity based on an inverse law is simply wrong.

Another comment linked to https://tritonstation.com/new-blog-page/, which is an excellent read. It makes the case that GR has never been tested at low accelerations, that is might be wrong. But we know for a fact MOND is wrong at high accelerations. Unless your theory can cover both, I don't see how it can be pitched as an improvement to GR.

Edit: this sounds a bit hostile. to be clear, I think modified gravity is absolutely worth researching. but it isn't a silver bullet

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meindnoch ◴[16 Nov 24 21:39 UTC] No.42159582[source]▶
>We know for a fact that gravity is _not_ Newtonian, that the inverse square law does not hold

[citation needed]

The consensus is that gravity - outside of extreme mass/energy environments - works just as Newton described it to many many decimal places.

Emphasized part added because people in the replies thought that I literally think that General Relativity is somehow wrong. Don't be dense. All I'm saying is that gravity at galactic scales works as Newton described it. General Relativity has extremely tiny effect at those scales.

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1. nimish ◴[16 Nov 24 23:52 UTC] No.42160651[source]▶
>The consensus is that gravity - outside of extreme mass/energy environments - works just as Newton described it to many many decimal places.

It absolutely does not. Newtonian gravity occurs instantly. It has no notion of information taking time to propagate. But we know gravitational waves happen, so Newtonian gravity is wrong _at even very large scales_. If the sun disappeared Newton tells us we'd know immediately. In GR we'd know about 8 min later.

The bigger problem is not that the quantitative effect is large, but that the _qualitative_ difference of going from the instantaneous effect to one that needs to propagate is enormous. It's the whole point of relativity as a concept.

Even going to GEM as a true, non-singular linear approximation of GR would be a step up from Newton's laws, at least there we can have gravitational waves and causal flow of information.

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2. the__alchemist ◴[17 Nov 24 13:01 UTC] No.42163985[source]▶
Thanks for bringing this up; this is the central reason why I'm skeptical of Newtonian models that predict dark matter, and why I don't think the term MOND makes sense as the simplest alternative.