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    James Webb Space Telescope finds evidence for alternate theory of gravity

    (thedebrief.org)
    355 points jchanimal | 12 comments | 16 Nov 24 18:33 UTC | HN request time: 0s | source | bottom
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    uoaei ◴[16 Nov 24 19:50 UTC] No.42158729[source]▶
    I follow the lead author, Stacy McGaugh, via his blog where he posts discussions and musings about the latest research into the dark matter vs MOND debate: https://tritonstation.com/new-blog-page/

    His arguments are very convincing and relatively clear. I am not an astrophysicist but I have two degrees in physics and have always found the dark matter theory to be lacking -- in absence of any evidence of causation whatsoever, dark matter can only be described trivially as "where we would put matter if we could to make our theory of gravity make sense," which is totally backwards from a basic scientific perspective.

    Predictions based on modern MOND postulates are shown to be more and more accurate as our observational instruments continue to improve in sensitivity.

    replies(4): >>42158855 #>>42158981 #>>42159032 #>>42159078 #
    1. simonh ◴[16 Nov 24 20:07 UTC] No.42158855[source]▶
    I don’t think that’s quite fair. That approach is exactly how we find planets. Here’s an unexpected variance in the motion of a planet or star. It could be explained by a planet over there. Oh look, there’s a planet over there.
    replies(4): >>42158901 #>>42158918 #>>42158941 #>>42159762 #
    2. TheOtherHobbes ◴[16 Nov 24 20:13 UTC] No.42158901[source]▶
    Planets are visible when you look for them.

    Dark matter - so far - isn't.

    replies(1): >>42160120 #
    3. MarkusQ ◴[16 Nov 24 20:14 UTC] No.42158918[source]▶
    Right, which is why it quickly led to the detection of dark matter...hmm.

    I think a better analogy would be "that approach is exactly how we explain failing to find planets like Vulcan; we hypothesize that they are made of as-yet-unknown stuff that you can't see, touch, hear, smell, or in fact detect at all. But we know they're there because our calculations say they are."

    4. solid_fuel ◴[16 Nov 24 20:16 UTC] No.42158941[source]▶
    Hypothesizing that a planet might be over there is a testable hypothesis.

    Have we found a way to verify the presence of dark matter yet? Or is it still an untestable hypothesis sprinkled around distant galaxies so their acceleration curves look right?

    replies(2): >>42159019 #>>42159237 #
    5. User23 ◴[16 Nov 24 20:26 UTC] No.42159019[source]▶
    I’m particularly amused by the hypothesis that spacetime can be bent without the presence of matter. We can’t detect dark matter because there’s no such thing, it’s just a brute topological fact.
    6. mr_mitm ◴[16 Nov 24 20:54 UTC] No.42159237[source]▶
    Dark matter predicted lensing effect which were successfully tested. Same for the baryonic acoustic oscillations in the CMB.
    replies(1): >>42159414 #
    7. MattPalmer1086 ◴[16 Nov 24 21:15 UTC] No.42159414{3}[source]▶
    That's not quite true. General relativity predicts gravitational lensing, not dark matter. Lensing has been used as an experimental probe for the presence of dark matter.
    replies(2): >>42159464 #>>42164245 #
    8. elashri ◴[16 Nov 24 21:21 UTC] No.42159464{4}[source]▶
    MOND is an alternative theory of gravity competing with GR. People usually forget that while MOND started to present a different explanation for Dark Matter, it is a theory of gravity. Dark Matter is not a theory of gravity and is compatible with GR.
    replies(1): >>42159811 #
    9. russdill ◴[16 Nov 24 22:04 UTC] No.42159762[source]▶
    It's actually a better example than you think. This exact theory led to long and protracted searches for the planet Vulcan, which would explain Mercury's strange behavior.
    10. zeroonetwothree ◴[16 Nov 24 22:10 UTC] No.42159811{5}[source]▶
    Dark matter isn’t much of a theory in the first place.
    11. drdeca ◴[16 Nov 24 22:48 UTC] No.42160120[source]▶
    What do you mean by “visible when you look for them”? Like, with light?

    Does gravitational lensing count as “visible” to you?

    12. mr_mitm ◴[17 Nov 24 14:09 UTC] No.42164245{4}[source]▶
    Well of course. What I clearly meant was that DM predicts lensing effects in a magnitude that cannot be explained with ordinary matter. See bullet cluster or weak lensing observations.