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I am instinctively skeptical of the existence of "dark matter" and "dark energy". Together, they strike me as being analogous to luminiferous aether -- something that was invented to explain a gap in our understanding that was actually due to our physical models being incomplete.

As far as I know, there is no widely-accepted physical model of dark matter/energy. So I don't see how it's very meaningful to even speak of it.

Why is it so normalised that people suppose dark matter/energy exists? Why is the prevalent understanding not something more along the lines of "clearly our equations for gravity are missing another term" (as in: different forces produced by the normal mass that we directly see)?

What is the argument that dark matter/energy is a better explanation than an alteration to our models for gravity involving normal matter?

Qmechanic
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spraff
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    Possible duplicates: https://physics.stackexchange.com/q/6561/2451 , https://physics.stackexchange.com/q/123131/2451 and links therein. – Qmechanic Feb 22 '24 at 10:13
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    The question incorrectly suggests that physicists are unwilling to adapt theory and act out of personal preference, whereas in fact it is the OP himself who is motivated by instinct, by his own admission. – my2cts Feb 22 '24 at 11:28

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People do not just "suppose" those things exist. They actually do try alternate explanations based on modified model equations, but in that way the observations can not be explained.

As for your question why the prevalent opinion is not: "clearly our equations for gravity are missing another term"? Well, that simply is not clear at all! It might just be that those equations are perfectly OK but that there exist dark matter and vacuum energy. Why do you think that "clearly" the latter option needs to be discarded and instead the equations should change?

Jos Bergervoet
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    In my opinion, the second part of your answer should be a comment. – Jeanbaptiste Roux Feb 22 '24 at 08:57
  • The second part actually addresses the only clear question OP asked (so it is an answer and not a comment!) Do you perhaps mean only the last sentence of that last paragraph, where I ask a counter-question? – Jos Bergervoet Feb 22 '24 at 09:00
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    The last sentence is indeed a comment. But I don't think contradicting OP's opinion is an answer per se. Maybe you could add why his/her opinion is flawed, apart from just "It might just be [...] dark matter and vacuum energy". I think OP is unaware of all the research on dark matter, for example. Sure there are alternatives like MOND, and they work "pretty well" on galaxies (see for example https://iopscience.iop.org/article/10.1086/305986/fulltext/37690.text.html#rf19), but fail at larger scales, where cold dark matter is predominantly considered. – Jeanbaptiste Roux Feb 22 '24 at 09:21
  • You are right, my answer is not giving the full justification of present-day opinion, but instead guiding OP (and others who might read this) to a more balanced approach of the problem. But is this wrong, giving this type of question? (It is often argued on this forum that we should not give full answers to very basic questions but leave some work for OP to do!) – Jos Bergervoet Feb 22 '24 at 09:32
  • I don't think this is wrong. And this is why I did not downvote your answer. It is true that very basic questions should not be fully answered, because it is unlikely that a similar question has not already been asked. But in that case, you might simply check if there are already similar questions and link them as comments. Of course, you can answer the way you did, but maybe OP will not be satisfied by this... – Jeanbaptiste Roux Feb 22 '24 at 09:44
  • Anyhow thanks for this discussion, as I'm relatively new in (actively) using this forum I'm interested in how these things should be handled! (Raised with usenet, where other rules prevail...) – Jos Bergervoet Feb 22 '24 at 10:12
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So far no modification of the theory has been proposed that can explain the observations. The radical hypotheses of dark matter and dark energy do offer the possibility to explain the phenomena.

my2cts
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Why are dark matter and dark energy favoured over changes to our physical models?

Because people haven't figured out the real explanation for the high-z anomaly, so they impose these 21st-century epicycles.

Space is an expanding sphere. Extreme distances are distorted by an "optical illusion" due to the extra distance from the curvature.

They think they're measuring a straight line, but it's the chord of a circle with circumference 2 pi * 14 billion LY. But the actual distance is an arc along the circumference of the ants' balloon.

As confirmation, if the balloon is expanding into future time, then the radius is its age. The universe's circum is expanding at 2 pi light-secs per sec always.

Just figure the Megaparsec's share of that second's worth of new space, and you get 70.9 Km/Sec/MPc. That's just 1.6% different from the accepted 73.5 ±1.4.

And if you toss in the uncertainty of the universe's age, the difference from the accepted value drops to 0.2%.

I mean, if you're interested. I pointed it out once, but nobody was.

I have a spreadsheet showing all this. I'll post it when I acquire a circular one of these.

L Turner
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