This biggest caveat is mentioned in the ApJL paper [0] introduction:<p>> Because SMBH growth via accretion is expected to be insignificant in red-sequence ellipticals, and because galaxy–galaxy mergers should not on average increase SMBH mass relative to stellar mass, this preferential increase in SMBH mass is challenging to explain via standard galaxy assembly pathways (Farrah et al. 2023, Section 5).<p>I think there are several observational effects that may obfuscate the interpretation -- but I also haven't read these papers in great detail.<p>First, there is a known age-metallicity-dust degeneracy that can make dusty star forming galaxies look more like red elliptical galaxies. This can bias estimates of the star formation and mass accretion history -- e.g. perhaps supermassive black holes have had more recent growth. Second, galaxies in more overdense regions may harbor faster growing supermassive black holes, and also be more predisposed to later merging and forming an elliptical galaxy. This seems likely true around cosmic noon (z~1-2), when star formation and supermassive black hole accretion activity were at their highest throughout cosmic history.<p>[0] <a href="https://iopscience.iop.org/article/10.3847/2041-8213/acb704" rel="nofollow">https://iopscience.iop.org/article/10.3847/2041-8213/acb704</a>
So increasing mass of black holes ... drive galaxies apart?<p>Since SMBH clearly act as massive gravity sink in close range, does this mean that black holes "take" vacuum energy, increasing its own mass and then stretching out spacetime? Does dark energy gets evenly distributed to black holes per mass or heavier black hole gets exponential larger servings? I have so many uninformed questions!<p>It seems more and more like some kind of scaling patch as the simulation gets larger and more out of hand. Here's to hope that the next patch are far away and if it does happen it doesn't break production.<p>How the patch notes might have looked like:<p>* Oops singularity bug happened, wrapping a black hole around it. Clever fix, they'll never suspect anything. If they did, they can't see through it anyways.<p>* This black hole feature is working very pleasantly, putting black hole seeds in center of galaxies so they can grow faster.<p>* Looks like the universe will collapse on itself soon with the added mass, quick fix to add a space time stretch around the black holes so it won't do that. Will have to think of a long term solution #TODO<p>... 3893 commits later<p>* who did the black hole space time stretch? the galaxies are flying apart and heat death is upon the simulation! Reopening #TODO.
The guardian also has an article about this:
<a href="https://www.theguardian.com/science/2023/feb/15/black-holes-contain-dark-energy-that-drive-expansion-of-universe" rel="nofollow">https://www.theguardian.com/science/2023/feb/15/black-holes-...</a><p>But if you’re interested in the details, the journal article is here:
<a href="https://iopscience.iop.org/article/10.3847/2041-8213/acb704" rel="nofollow">https://iopscience.iop.org/article/10.3847/2041-8213/acb704</a>
I'm surely missing something in the paper, but I'm having a hard time seeing how the fact that black holes gain mass in a way that is seemingly coupled with the rate of expansion of the universe mean that it's driving the expansion - couldn't the universe just be expanding, giving the black holes the energy they would need to get this large?<p>Super interesting papers!
From a quickscan it seems the theoretical basis for the work is revisiting how one stiches together relativistic descriptions of compact objects to cosmological solutions. This cannot be done exactly, some approximation is required. The authors revisit the perturbation theory that was used in classic papers and argue an alternative approach that effectively brings additional "physics". In their first paper [0] they suggest that binary neutron stars, being a relativistic compact object should also exhibit "cosmological coupling". Not clear where this stands.<p>[0] <a href="https://iopscience.iop.org/article/10.3847/1538-4357/ab32da" rel="nofollow">https://iopscience.iop.org/article/10.3847/1538-4357/ab32da</a>
At first glance this looks like it would suggest that black hole formation is directly related to the cosmological constant, which suggests that as the universe expands and (eventually) black hole formation slows down as the density of regular matter in the universe decreases, the whole thing should reach an equilibrium? Any cosmology-literate physicists here want to comment?
I have to admit I don't get it.<p>Ordinarily I think of a black hole as being a pretty ordinary gravity source when you are far away from it. If our sun got turned into a black hole by some non-violent process the planets would keep orbiting around it the same way around. How it contributes to dark energy is beyond me (like... nothing is supposed to leave a black hole!)<p>It reminds me of a 1970s sci-fit book where the bad guys were trying to prevent the universe from collapsing (people thought the universe was closed, not flat then) and managed to momentarily reduce the mass of the universe by manipulating a black hole so their evil computer could live forever in an eternally expanding universe. The good guys countered this plan with a ship that traveled close to the speed of light, increasing its mass, and causing the universe to collapse. On top of that they used a black hole to create a time loop causing the events that made the ship leave.<p>Needless to say, none of the above is expected to work.
I kind of dislike cosmological / astronomical science. It's strictly non interacting. It's predicting a function of only output and not inputs. Sure, the number of outputs is large. But without any inputs, it's just a funny compression competition.<p>So long as we can't interact with it, I don't think there's any way to distinguish between ideas. Note that the only reason Newton managed to surpass his predecessors was because of his insight that whatever it was that's pulling the stars is also the same thing we have locally. Without having something to play with locally, we'd never get anywhere. Sure, you might realize that somehow the epicirles are actually ellipses, or find this or that correction. Still you'll get nowhere without something interactive and local.
I read the article, but not the paper. The article's quite popsci, I think.<p>No doubt I misunderstood, but it sounds like circular reasoning:<p>* Cosmic expansion of spacetime causes expansion of black holes<p>* An expanded black hole must have greater mass<p>* Increasing mass of black holes results in cosmic expansion of spacetime<p>I had also understood that cosmic expansion affects the empty space between galaxies, and doesn't affect concentrations of mass like galaxies and black holes. IOW, expansion causes galaxies to move further apart, but not stars in galaxies. If that's right (I assume it isn't), then cosmic expansion shouldn't be able to cause a black hole to expand.
This seems like a huge deal if it pans out? Any astrophysicists around who call tell how solid this evidence looks? Is it the sort of thing that could easily go away with more data?
> What that means, though, is not that other people haven’t proposed sources for dark energy, but this is the first observational paper where we’re not adding anything new to the universe as a source for dark energy: Black holes in Einstein’s theory of gravity are the dark energy.”<p>I beg to differ. This man has developed a theory of black holes without singularities called plugstars with a maximum gravitational redshift factor of 3, just like in OP article.<p><a href="https://hal.science/hal-03835483/document" rel="nofollow">https://hal.science/hal-03835483/document</a><p>edit : the article talks about a k factor of 3, not sure whether it matches Petit's plugstar redshift factor of 3.
Wait so does energy have mass? Assuming the total amount of mass in the universe is the same, and black holes absorb mass and then slowly evaporate into energy with Hawking radiation, does the total mass in the universe keep changing?
It replaces singularity at the center of Black holes and brings in Vacuum Energy in its place.<p>But I thought Vaccum Energy theory isn't proven in practice, in the sense there's huge discrepancy between theoretical value vs observed.<p>Anyway it would be interesting to watch where this goes.
I can't wait for the inevitable Sabine Hofstadter video that either call out an obvious flaw or go into the consequences/implications of what it may change if it turns out to be true.<p>I also can't wait for the Space Time video on this once it had enough peer review to report on.
Other related thread: <a href="https://news.ycombinator.com/item?id=34818078" rel="nofollow">https://news.ycombinator.com/item?id=34818078</a><p>My comment on that thread: <a href="https://news.ycombinator.com/item?id=34819406" rel="nofollow">https://news.ycombinator.com/item?id=34819406</a>
Is there some coagulated astrophysical theory about reality being black holes all the way down? I.e. our universe being a region of spacetime isolated inside a black hole, each black hole inside our universe also hosting one, the expansion of the universe possibly being the black hole growing, etc?
Am I right in thinking that if this connection is confirmed then it'll bring us a step closer in bringing Quantum Mechanics and General Relatively closer together?<p>After all, vacuum energy/zero point energy/ZPE is a quantum phenomenon, albeit not that well understood.
The containment of vacuum energy instead of a singularity aligns well with my ideas on black holes. But this correlation to dark energy seems in contradiction — dark energy is essentially the cosmological constant. How can increasing mass over time cause acceleration of the expansion rather than deceleration? Something doesn’t jive here. (Hopefully the paper will shine some sense on this.)
According to Einstein matter equals energy.
So how is it possible to discern between dark energy and dark matter.
They could be indistinguishable, no?<p>do you think this will still hold<p>DE=DM*cˆ2