Yes, I've seen the headlines saying that black holes may be dark energy. I think that's extremely implausible. A brief ๐งต 1/
theguardian.com
theguardian.com
First of all, the statement is immediately contradictory because what we mean by "dark energy" is defined by having a particular equation of state. A collection of black holes does not have the right equation of state, so it can't be dark energy. 2/
Of course maybe they are saying there's something very unusual going on with these black holes, so I look at the paper and the point isn't discussed. BIG RED FLAG ๐ฉ๐ฉ๐ฉ 3/
Instead they basically say the following: We have evidence that supermassive black holes (SMBH) grow faster than expected. This has been known for a long time, but they have new data and all, very neat. 4/
Then they say, we ASSUME that this extra growth comes from a cosmological source. And then there's some bla-bla about pressure and energy conservation saying that therefore it needs to be a type of dark energy. I can't follow the argument. 5/
This means the argument in the paper basically comes down to saying: We have two things that we don't understand (a) growth of supermassive black holes and (b) the origin of dark energy. We assume they're linked and if we assume they're linked the stat significance is high. 6/
To say the hopefully obvious, assuming that two things are related doesn't show they're related. 7/
I didn't spend a terrible lot of time reading this paper (as you can guess), so I'm shooting from the hip here, but I give it a 99% chance you'll never hear of this supposed breakthrough again. 8/
I am guessing the papers (it's two) got published because there's a fair amount of data analysis going on etc, which all looks very good. As I said, we've known for some time something about supermassive black holes isn't checking out, this is all well and fine. 9/
But I don't believe the stuff about dark energy for a second because I'm missing the relevant equations that would show how this works. /end
Correction: I shouldn't have said they have new data. It's a new data analysis.
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