I'm curious to know if any mainstream theoretical physicists have theorized or spoken about the possibility of a theory of dark matter that doesn't involve any actual matter like hypothesized MACHOs or WIMPs.

The thought experiment this leads me to is the classical "bowling ball on a rubber sheet" demonstration of how matter curves spacetime through mass, with a black hole being better represented by e.g. a hook in the bottom of the sheet that is then pulled an infinite distance away.

In essence, my question is, is it possible for there to be similar "dimples" in the fabric that have mass, but without hypothetical particles like MACHOs, WIMPs, or other types of matter? Such as a source of energy that curves spacetime?

I've been looking for any examples of such a theory but have been unable to find anything, so I either lack the right terminology for my search, or there's some reason that such an idea has been considered and discarded without any fanfare.

  • $\begingroup$ I don't have a specific scientific answer to this question, just want to add that MOND (modified Newtonian dynamics) is the primary "alternative" to dark matter theory. In extragalactic astrophysics, Lambda-CDM is generally preferred over MOND, based on the kinematics and mass inventories of galaxy clusters. However, MOND still makes some interesting predictions and has some observational evidence, so you might check it out. $\endgroup$
    – zh1
    Feb 22, 2021 at 2:35
  • $\begingroup$ First, we consider mass and matter as separate and distinct is a non-sequitur. with mass being the fundamental curvature of spacetime caused by both matter and energy is also a non-sequitur ...mass is the measure of the quantity of matter. Do you mean that "mass is the cause of curvature"? matter curves spacetime through mass is a non-sequitur. Your question is very contradictory and does not appear to make sense. Can you try to reword it? And I'm not sure it will be answered as we deal with mainstream science. $\endgroup$
    – joseph h
    Feb 22, 2021 at 2:47
  • $\begingroup$ I'm posting this as a comment because I am not confident it's correct. If there are dimples in space-time such that there is gravity without matter, then the laws of physics must vary with location. In other words, you need one set of laws of physics in the places with gravity without matter, and another set of laws of physics in the places where there needs to be matter to have gravity. If the laws of physics vary with location, then linear momentum would not be conserved, by Noether's theorem. If we observe conservation of momentum (we do), that renders this idea unworkable. $\endgroup$
    – Allure
    Feb 22, 2021 at 4:17
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    $\begingroup$ @alzee OK. The question you ask is a good one. Well done. Cheers. $\endgroup$
    – joseph h
    Feb 23, 2021 at 23:44
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    $\begingroup$ @josephh thanks for your help in formulating it. Maybe in time it'll turn up some interesting not-yet-mainstream-but-not-crackpot theories that I haven't heard of. $\endgroup$
    – alzee
    Feb 25, 2021 at 20:22

1 Answer 1


Dark mass is the 'stuff' that fills 'empty' space that is displaced by ordinary matter. Dark mass displaced by the quarks the Earth consists of is the physical manifestation of curved spacetime. The dark mass displaced by a galaxy 'displaces back', causing the stars to orbit the galactic center at the rate in which they do.

  • $\begingroup$ Do you have a reference for this theory, or is it your own idea? (Note that the OP is looking for a mainstream theory, and non-mainstream physics is off-topic on this site). It's an interesting concept, but I don't think it squares with our observations of how light behaves as it travels through the huge voids between galaxy clusters. $\endgroup$
    – PM 2Ring
    Feb 22, 2021 at 21:02
  • $\begingroup$ Physicists analyze rotational dynamics of galaxies and influence of the photon mass > the mass of photons, which are particles of light is responsible for the rotational dynamics of galaxies $\endgroup$ Feb 22, 2021 at 21:13
  • $\begingroup$ Dark mass is a sea of massive photons displaced by ordinary matter (quarks). $\endgroup$ Feb 22, 2021 at 21:13
  • $\begingroup$ @PM2Ring is correct, I'm not looking for any sort of fringe theory or "idea" abusing the word theory, but something considered or posited by respected mainstream physicists. If Cox, Greene, or Carroll would call it a crackpot idea or haven't even heard of it, then it's not what I'm after here. The link you provided is interesting, but doesn't address the question. I'm not looking for a theory that is simply named "dark mass" but a specific idea. $\endgroup$
    – alzee
    Feb 23, 2021 at 0:11

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