Assuming DE exists as per LCDM standard model suggests, it has the purported repulsive property according to p (pressure) = -ρ (net matter-energy density).
which is net repulsive since the collective gravitational source density is given by p + 3ρ -> -2ρ which is negative.
A standard position. Hence swallowing of notional DE by a BH should logically decrease not increase it's mass! Completely contrary to the following articles claim:
https://phys.org/news/2023-02-scientists...ource.html
https://iopscience.iop.org/article/10.38...213/acb704 (linked to in above article)
Well let's suppose DE mysteriously does an about face inside a BH and actually adds to it's mass.
How could growth of inherently gravitationally attractive BHs via sucking in DE actually be the notional gravitationally repulsive DE on a cosmological scale?
Especially given the standard position wrt DE is that it's an inexhaustible resource that doesn't dilute with cosmic expansion, unlike matter density.
The universe goes crazy trying to peer up it's own backside? I realize this is the wrong site to expect useful input, but it may prove amusing.
[OK so some further thought and it seems the claim is BHs grow by expelling radially a continual stream of DE created within them. Interesting - since it implies a massive net violation of conservation of energy, even assuming the net gravitating 'mass' is conserved.
(Actually net gravitating source density must have a negative value to be in accord with apparent cosmological accelerated expansion. But see e.g.
https://arxiv.org/abs/1507.07809)
Given DE has positive energy density, and of course the BH also has a positive energy associated with it's mass. This radical notion will for sure invite a lot of blow-back!]
Kornee Wrote:I realize this is the wrong site to expect useful input, but it may prove amusing.
I can work with that.
My plan is to learn GR one day..
Oz is an apprentice wizard and the Wizard is a real wizard who keeps his mathematics at the back of his cave.
Oz and the Wizard:
https://math.ucr.edu/home/baez/gr/oz1.html
So .. a bit of a challenge ...
Can you (or I) find any dark energy starting with a ball of coffee grounds?
Bearing in mind that I know nothing..
My first stab would be to take one of those Chinese balloons into space, loosely inflate it and float coffee grounds around inside it.
Take away the coffee grounds and the balloon kind of gets bigger*.
Adding the beans to a bigger pile gives you some smallification but less smallification than the bigification than you got when you took them out of the balloon.
You got anything better? I feel zero point energy ought to come in somewhere .. but where?
* edit non-locally
I don't get the drift. Intuitive connections between physical models and Ricci or Weyl curvature is better fleshed out here:
https://arxiv.org/abs/gr-qc/0103044v5
Where is the relevance to the radical claims made in the articles linked to in #1? The new claim is a spectacular violation of what till now has been taken as sacrosanct in GR. Namely, ∇T_ab = 0 (continuity relation for gravitating source density).
I have shown many years ago that sacrosanct relation falls apart when GWs are analyzed, or via a very simple gedanken experiment. But those cases have no bearing on what is being claimed above.
Namely, that a 'static' BH continually generates and expels DE while simultaneously growing in mass.
The whole enterprise ignores the implications of coordinate time freeze at and below the EH. Namely, that any purported coordinate determined outgoing DE flux rate, generated below the EH, is logically zero. A complete writhing can of worms.
Keeping it very very simple for my benefit.
I would expect that for any region of space what is contained within will be
what started there + what arrived - what left.
(Kirchoff's law for electrical engineers)
My interpretation of the OP is that in that in the region of Black Holes more comes out than goes in
"The new result shows that black holes gain mass in a way consistent with them containing vacuum energy, providing a source of dark energy and removing the need for singularities to form at their center."
AND what comes out reaches 'us' in a finite time .. both very odd things.
Everything about growing BHs spewing out DE is iffy to say the least. It ditches the usual notion of an ever present uniform DE background.
Instead, we have sparsely peppered reverse sinkholes. What velocity do the DE clouds spread out at? With a net negative gravitating mass density, who knows.
Trying to fit it to a standard wave equation is likely impossible.
I'll be on the lookout for that inevitable blow-back mentioned in #1.
And it hasn't taken long - from the source I expected it from:
https://bigthink.com/starts-with-a-bang/...rk-energy/
As pointed out, the purported 'coupling' has no theoretical underpinning and is purely a speculative idea based on an intriguing phenomenological finding.
The assumed p = -ρ composition of DE 'outflows' is inconsistent with it being either a curvature constant of spacetime itself, or owing to 'vacuum zpe'. And would have to be some additional field - yet with precisely the p = -ρ form of either of those.
A flash in the pan with a salutary warning about reading too much into numerical coincidences. Or so I assert....
There will be many other inputs no doubt but on this one I will here give Ethan a tick (sans his unquestioning belief in BHs - but that's simply conforming to majority opinion).
Slightly off-topic but heres my take on Gravity.
Gravity to my knowledge isn't one directional (consider it a by-product of a combined volume of matter oscillating at macroscopic levels to create a unionised field). If anything it's likely a fluctuation of fields that happens to have larger wavefunctions in one direction and smaller ones in the other (Consider the attraction to one side of the planet would both be at greater distance and counter to the otherside of it).
The rationality is that that the larger (or smaller) would generate a greater force that attract other volumes. That wavefunction/field wouldn't be countered by the lesser repulsion field (as the lesser wave is "shifted" in relationship to it). However not everything has mass (such as the fields themselves) which leads to the potential of those fields being repulsed even though observably gravity attracts.
If you apply that rationality, then it explains simply why a field can escape from a "blackhole" while matter (or more precisely electromagnetic forces) are attracted.
Personally (This is not necessarily mainstream, so take as you will.) I'm not too much a beliver of the current theory of blackholes but that's because I had a different model of the universe where any given unit of space actually has an upper-bound as to how much energy (e.g. matter) can occupy it. The only way a blackhole could therefore exist requires it to occupy a larger amount of volume space (Namely it might occupy one space but speghettifies across multiple volumes from it's curvature, which would course be possible if the "zpe" was actually a medium to that volume)
In other words if space was completely absent of a medium (and therefore "tunnelling"), you couldn't compress anything into it as a volume as it would limited by its bound.
(Feb 18, 2023 08:08 AM)stryder Wrote: [ -> ]Slightly off-topic but heres my take on Gravity.
Gravity to my knowledge isn't one directional (consider it a by-product of a combined volume of matter oscillating at macroscopic levels to create a unionised field). If anything it's likely a fluctuation of fields that happens to have larger wavefunctions in one direction and smaller ones in the other (Consider the attraction to one side of the planet would both be at greater distance and counter to the otherside of it).
The rationality is that that the larger (or smaller) would generate a greater force that attract other volumes. That wavefunction/field wouldn't be countered by the lesser repulsion field (as the lesser wave is "shifted" in relationship to it). However not everything has mass (such as the fields themselves) which leads to the potential of those fields being repulsed even though observably gravity attracts.
If you apply that rationality, then it explains simply why a field can escape from a "blackhole" while matter (or more precisely electromagnetic forces) are attracted.
Personally (This is not necessarily mainstream, so take as you will.) I'm not too much a beliver of the current theory of blackholes but that's because I had a different model of the universe where any given unit of space actually has an upper-bound as to how much energy (e.g. matter) can occupy it. The only way a blackhole could therefore exist requires it to occupy a larger amount of volume space (Namely it might occupy one space but speghettifies across multiple volumes from it's curvature, which would course be possible if the "zpe" was actually a medium to that volume)
In other words if space was completely absent of a medium (and therefore "tunnelling"), you couldn't compress anything into it as a volume as it would limited by its bound.
Perhaps if numerical results can be extracted from some relevant equations.....
I'll give you this much as a very tentative connection to an idea with some logical underpinnings I liked:
Consider gravity as actually a 'byproduct' of inertia a la Mach's Principle. Then it has been shown that gravitational attraction of matter follows as a result of differential inertial mass reactions across an extended particle that necessarily has inherent motional fluctuations a la Heisenberg's Uncertainty Principle. Can't recall where I came across the article, but recall thinking that was already something I had thought of independently.
Some are putting the cart before the horse, and taking the hypothesized BH-DE linkage as BH growth being driven by 'linkage' to existent DE in an expanding cosmos.
Rather than DE being generated and expelled somehow by growing BHs. e.g. #7 & #8 here:
https://www.physicsforums.com/threads/bl...y.1050066/
Fantasy either way. The effect of accelerated Hubble expansion (IF it's even real) is so feeble it's only significant on galactic supercluster scales and above.
But the numerical coincidences uncovered are enough for even some GR buffs to seriously entertain Hubble expansion could 'pull BHs outward' as suggested.
[Actually, given that BHs with one-way EHs don't exist.... I'll entertain the outside chance something truly weird happens deep in the interior of a physically self-consistent collapsed object with exponential metric.
There is then always the possibility of escape, but even so the purported mass growth + expelled DE as earlier mentioned, necessarily wildly violates conservation of energy.
I've yet to see anyone else pick up on that unavoidable consequence.]
I'm not sure how one seemingly rational GR buff over at PF in above mentioned thread (p1 #14), thinks the purported DE/vacuum energy driving inflation never gets out of the 'BHs' but contributes 'inside'.
Implying net negative mass BHs. Which reasoning ignores that the elliptic galaxy SMBH surveys are all based on positive mass estimates for such central SMBHs.
(Indeed, runaway dynamic instability would long ago have driven any negative mass SMBH out of the galaxy. Assuming they could even form in the first place!)
Hence if there is no outflow of negative source density DE, the net effect of growing positive mass BHs would necessarily be decelerating expansion. So much screwy thinking from a premier physics site!
[CC has decided there is a need to double report on the topic. Whatever.]