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One of the ideas that might solve some of the dark matter problem are the existence of many small black holes. There is evidence, in principle, for the existence of these small black holes via the theory of "primordial black holes". If we find that these black holes are more abundant than the theory predicts (perhaps due to a miscalulation), then they could go further to explaining the missing matter.

If these small black holes are common, and we know that black holes consume matter, then wouldn't a cosmological model have to be updated to include lots of matter being consumed during expansion, say during inflation and shortly thereafter? Has this been accounted for?

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  • $\begingroup$ I am proposing this "consuming matter" correction to expansion models as a test of the presence of many primordial black holes. Is any of this possibly correct? Questions about the general correctness of unpublished personal theories are off topic. $\endgroup$
    – Vincent Thacker
    Commented May 10 at 14:36
  • $\begingroup$ Underlying question is about mainstream physics, though. I reworded the question and voted to reopen. $\endgroup$
    – Sten
    Commented May 10 at 15:46
  • $\begingroup$ Minor comment to the post (v3): Please consider to mention explicitly author, title, etc. of link, so it is possible to reconstruct link in case of link rot. $\endgroup$
    – Qmechanic ♦
    Commented May 10 at 15:51
  • $\begingroup$ Some info about primordial BH size range: physics.stackexchange.com/q/505981/123208 There's a question about primordial BH detection, but the answers don't have much info: physics.stackexchange.com/q/10731/123208 $\endgroup$
    – PM 2Ring
    Commented May 10 at 21:57

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If we are thinking about gravitational mass then a black hole does not "consume" matter. The gravitational mass of the black hole is essentially the same (certainly at large distances) as the gravitational mass of the matter that has fallen into it. So as far as large scale gravitational effects are concerned, there is no "missing matter" here.

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  • $\begingroup$ Your answer misinterprets the question. The current cosmology assumes a constant amount of baryonic matter in the universe equal to the current observed amount. If much matter has been consumed by black holes, then there was more baryonic matter in the past than the current cosmology measures. Since the gravity of this matter remains unchanged after the consumption, the current amount of “baryonic” matter (including the black holes) should be the same as in the past and more than per the current cosmology. The OP refers to the difference as the “missing matter” that should be accounted for. $\endgroup$
    – safesphere
    Commented May 20 at 3:32
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Primordial black holes may account for some or all of dark matter. The "primordial" tag refers to them being created before the epoch of nucleosynthesis.

The reason for that distinction is that there are constraints on the amount of baryonic (and hence by implication, dark) matter from the primordial abundances created during the epoch of nucleosynthesis. Matter that is "consumed" after that by black holes is going to be mostly baryonic matter (since that is the only matter that can readily lose energy and angular momentum and be captured by a black hole).

Baryonic matter that is hidden in black holes isn't a problem. There may well be some. In fact that would help in accounting for the gap between the amount of baryonic matter we know about in terms of stars and gas and that inferred to have been present at the epoch of nucleosynthesis.

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