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James Webb Space Telescope finds evidence for alternate theory of gravity

(thedebrief.org)
355 points jchanimal | 1 comments | 16 Nov 24 18:33 UTC | HN request time: 0.208s | 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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1. phkahler ◴[17 Nov 24 17:01 UTC] No.42165272[source]▶
IANA physicist but everywhere I look I see the same mistake being made. The shell theorem does not apply to disks or galaxies.

I see the same simplification in the most advanced writings. Namely 1) matter out to a radius can be treated as a point mass in the center and 2) we can ignore gravity from mass outside a radius because it all cancels.

These simplifications work for spherical shells or solids of uniform density. They do not apply to disks or rings (galaxies). Period.