this post was submitted on 17 Mar 2024
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Absolutely. On the one hand, having ~26% of the known universe consisting of a substance that we cannot detect directly leaves a lot of questions open. On the other hand; dark matter is postulated because otherwise things like galaxy rotation curves don't match what we believe they should be from general relativity, and this theory doesn't seem to address that.
https://en.wikipedia.org/wiki/Bullet_Cluster#Significance_to_dark_matter
Also, light 'losing energy' would be a violation of the first law of thermodynamics, unless it loses it 'to' somewhere.
Light does actually just lose energy to nowhere in our current understanding of expanding space.
How does this reconcile with the first law of thermodynamics? Or does it just not?
Iβm no expert, and I donβt think we know for sure, but it sounds like it might be related to the increase in vacuum energy from the added space. Itβs also possible the total amount of net energy in the universe is 0 and conserved
At some point we may have to review some theories though. The idea that light would lose energy over extra long distances at least makes sense unlike some kind of latter that we can't detect and we can't figure out why it would either still be there but not more than it is.
This is kind of how time was supposed to be absolute. Einstein never received a Nobel for the theory of relativity because of how suspicious it seemed at the time.
There being a substance that does not interact with light at all doesn't seem that far fetched to me. There is nothing in the laws of the universe that says "Humans must be able to detect everything that exists because otherwise it wouldn't make sense."
It feels entirely possible that we won't be able to detect dark matter through any conventional means that we currently have.
It's not about humans. It's about science. "there is dark matter that doesn't interact with matter" can as well be "there is magic, and I cannot be proven wrong".
Dark matter does interact with matter, though: it interacts gravitationally. It just does not interact in other ways (that we know of yet). All you would have to do to disprove the existence of dark matter is to show that some things interact with it gravitationally but others don't. However, this is not what we see; what we actually see is a whole bunch of separate things that all experience the effect of the existence of dark matter in the same way. It's effectiveness as an explanation in this regard is exactly what makes it so difficult to dethrone.
Dark matter is exactly like adding a constant to your equation so that it fits the numbers.
If by "constant" you mean "3D distribution that explains not just one equation but lots of separate observations", then sure, it's just like that.