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Scientists find first observational evidence linking black holes to dark energy

278 points by negativelambda 4y ago

habibur 4y ago
It replaces singularity at the center of Black holes and brings in Vacuum Energy in its place. But I thought Vaccum Energy theory isn't proven in practice, in the sense there's huge discrepancy between theoretical value vs observed. Anyway it would be interesting to watch where this goes.
nathan_compton 4y ago
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?
negativelambda 4y ago
The guardian also has an article about this: https://www.theguardian.com/science/2023/feb/15/black-holes-contain-dark-energy-that-drive-expansion-of-universe https://www.theguardian.com/science/2023/feb/15/black-holes-... But if you’re interested in the details, the journal article is here: https://iopscience.iop.org/article/10.3847/2041-8213/acb704 https://iopscience.iop.org/article/10.3847/2041-8213/acb704
jachin 4y ago
[flagged]
- negativelambda 4y ago
  That reminds me of the Red Dwarf episode: https://youtu.be/SqI41N4WGPM https://youtu.be/SqI41N4WGPM
  - dylan604 4y ago
    Non-sequitor, but I grew up watching Red Dwarf with BBC on PBS. I never had a cat as a kid, so that character was totally bizarre to me. Now after being a cat "caretaker", I think owner is not quite right, I totally understand that character. This made rewatching that series so much more enjoyable. The story of his audition is still one of my favorites: "On television, John-Jules is best known for his portrayal of Cat and Cat's geeky alter ego Dwayne Dibbley in the British comedy series Red Dwarf. He obtained the part of Cat by turning up half an hour late for his audition, dressed in his father's old zoot suit. He was unaware that he was late and hence did not appear at all concerned about it. The producers immediately decided he was cool enough to be "the Cat"." --wikipedia
- Nevermark 4y ago
  I hereby coin the linkage between Dark Energy and Dark Stars ... "Dark Synergy"! Unfortunately, the Dark is scary, as far as I can tell. If black holes masses keep increasing, and the universe keeps accelerating in size, we end by stretch of by crush. Or does one of these effects ever win? Is there any hope for a middle case where we get through?
mtlmtlmtlmtl 4y ago
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?
jwuphysics 4y ago
This biggest caveat is mentioned in the ApJL paper [0] introduction: > 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). I think there are several observational effects that may obfuscate the interpretation -- but I also haven't read these papers in great detail. 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. [0] https://iopscience.iop.org/article/10.3847/2041-8213/acb704 https://iopscience.iop.org/article/10.3847/2041-8213/acb704
- xqcgrek2 4y ago
  Are those two effects big enough to make a false signal as big as the purported signal? They seem like relatively minor annoyances.
  - _0w8t 4y ago
    I also think that the estimated growth was too big to be caused by such systematic errors. On the other hand we do not have models of a galaxy evolution based on solving equations of General Relativity. Typically the assumption is that Newtonian gravity with minimal relativistic corrections should be enough. But there is no proof that it is so. Moreover, there were relatively recent papers that showed that better accounting for General Relativity could be enough to explain rotational curves for Galaxies without any notion of Dark Matter and that the need for Dark Matter was simply ab artifact of the assumption that Newtonian gravity can be used at the galaxy scale. Then there are speculations that electromagnetic forces do play role at the galaxy scale affecting the rate of evolution of galaxies. So it can be that the observed discrepancy in the growth of Black Holes caused by holes in galaxy evolution models, not by the proposed new effect.
spartanatreyu 4y ago
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. I also can't wait for the Space Time video on this once it had enough peer review to report on.
- mindcrime 4y ago
  I can't wait for the inevitable Sabine Hofstadter video that either call out an obvious flaw... I'm guessing you meant to say Sabine Hossenfelder[1]? [1]: https://en.wikipedia.org/wiki/Sabine_Hossenfelder https://en.wikipedia.org/wiki/Sabine_Hossenfelder
  - spartanatreyu 4y ago
    Yes your right, I typed the name into google to get it to autocorrect for me (I hadn't had enough caffeine yet) and google autoco-wrecked me instead.
  - Eupraxias 4y ago
    I made the same mistake once myself, but feel that Sabine should feel honoured to be slipped for Douglas.
    - mindcrime 4y ago
      Fair point! Now for somebody to slip and call her Sabine Hasselhoff...
      - sohkamyung 4y ago
        I guess this is in reference to some videos she made of herself singing? :-)
        1over137 4y ago
        And because she's German, and the Germans love David Hasselhoff. :)
Aperocky 4y ago
So increasing mass of black holes ... drive galaxies apart? 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! 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. How the patch notes might have looked like: * 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. * This black hole feature is working very pleasantly, putting black hole seeds in center of galaxies so they can grow faster. * 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 ... 3893 commits later * who did the black hole space time stretch? the galaxies are flying apart and heat death is upon the simulation! Reopening #TODO.
- ilrwbwrkhv 4y ago
  Hopefully on-call is solid
  - Aperocky 4y ago
    bad news: we're actually alpha and this eon's intern just submitted their first commit.
    - steve_mcdougall 4y ago
      @Jehovah just circling back to some interesting decisions you made previously. Please pop into my office when you have some time to discuss.
      - deleted 4y ago
        [deleted]
bobse 4y ago
>dark energy When will this meme die?
- jfengel 4y ago
  When something better comes along to replace it.
  - bobse 4y ago
    DARK GOD
  - JKCalhoun 4y ago
    I don't know, can't you be skeptical of a thing without having a better alternative?
    - smolder 4y ago
      Yes.
    - jfengel 4y ago
      You can. But thinking it's a "meme" that should "die" is not being skeptical. It's the best current explanation, and an uninformed dislike is not to be mistaken for an understanding of its limitations.
dmbche 4y ago
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? Super interesting papers!
- leereeves 4y ago
  Unfortunately the article seems to gloss over that point with just one sentence: > The conclusion is profound: Croker and Weiner had already shown that if k is 3, then all black holes in the universe collectively contribute a nearly constant dark energy density, just like measurements of dark energy suggest. That sentence contains a link to a paper[1] that's highly technical and beyond my understanding of physics, but concludes: > A population of such stellar-collapse remnants can shift in energy $\propto a^3$ while diluting in number density $\propto 1/{a}^{3}$. The population-averaged energy density is then effectively constant and readily produces the observed ${{\rm{\Omega }}}_{{\rm{\Lambda }}}$. which matches the claim in the article. But to understand why, I guess we'd have to learn general relativity to understand the math in that paper. 1: https://iopscience.iop.org/article/10.3847/1538-4357/ab32da#apjab32das5 https://iopscience.iop.org/article/10.3847/1538-4357/ab32da#...
transfire 4y ago
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.)
hoseja 4y ago
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?
college_physics 4y ago
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. [0] https://iopscience.iop.org/article/10.3847/1538-4357/ab32da https://iopscience.iop.org/article/10.3847/1538-4357/ab32da
kiviuq 4y ago
According to Einstein matter equals energy. So how is it possible to discern between dark energy and dark matter. They could be indistinguishable, no? do you think this will still hold DE=DM*cˆ2
- Sharlin 4y ago
  They are entirely different things, only related by the word “dark”. Dark energy is “negative” energy in the sense that it drives expansion rather than slowing it down. Its energy density is also constant, meaning it is not diluted by expansion unlike matter (dark or not) and normal energy. It seems to be a fundamental property of spacetime.
- ben_w 4y ago
  The reason they even came up with the idea is because they're distinguishable. Unfortunately, my mental model is merely one step up from PopScience articles, so the following probably has more holes than a doughnut carved out of Swiss cheese: Dark matter was first noticed in the unexpected relationship between the orbital speed of stars in galaxies and their distance from the centre. This has since been improved by the direct observation of gravitational lensing, which also shows its not "simply" gravity falling off at a different rate that 1/r^2 at these scales as the lensing isn't always inside the galaxies e.g. when two collide. Dark matter behaves like it doesn't interact with anything much, not even itself. On the other hand, dark energy was originally suggested by Einstein as a fudge factor to make the universe static on large scales, something he later dropped in embarrassment when Hubble expansion was found, only for it to come back when people noticed the expansion seemed to be accelerating. Dark energy, for maths reasons I don't really understand[0], acts like negative pressure even though it's positive energy, which occupies all space evenly and therefore has an effect directly proportional to distance, not inverse squared like gravity. [0] 16 simultaneous partial differential equations whose contents can vary throughout a 3+1 spacetime is something I have yet to even attempt to play with
  - raattgift 4y ago
    > Dark energy, for maths reasons I don't really understand[0], acts like negative pressure even though it's positive energy First, let's understand a bit about the cosmological frame: it lets us consider the universe as 3-dimension-of-space ordered by a "scale factor" dimension of time. The coordinates of each 3d space are Euclidean, but the coordinates don't line up exactly between different scale factors. Colloquially, the coordinates expand with the expansion of space, or equivalently the space between coordinates grows over time. You could think of it this way: if at some early point we label every point in space with an integer, in the future of that point we have to add new labels between the integers. If we add in a pair low-mass freely-falling test matter at the time when everything is labelled with an integer, e.g. at point (1,1,1) and (2,1,1), then they stay at those coordinates even as more and more labelled (with non-integer) space appears between them. To this we add a set of gasses, dusts, or fluids representing radiation, ordinary nonrelativistic matter, and maybe others (e.g. relativistic dark matter (e.g. neutrinos), non-relativistic dark matter ("cold dark matter"/"particle dark matter")). Again, any "mote" of the ordinary matter dust stays at the same coordinate forever. Rather than coping with the "motes" of radiation not staying put, we average every point in space and see there is some quantity of matter (a mote, or a fraction thereof), some quantity of radiation (a mote, or a fraction thereof), some quantity of dark matter, and so forth. The dusts dilute away because more and more space appears between each original coordinate. In our averaging picture, we get a smaller and smaller fraction of a mote at eacn point on average as the universe expands. This is the essence of the Friedmann-Lemaître-Robertson-Walker model that is the standard cosmology. The view here is that of boring old observers freely floating in deep inter-galaxy-cluster space. That leads to (from that view point) concrete calculations of the various contributions to the averaged energy-density at each point in space at a particular scale factor ("at a given age of the universe"). In general, that figure is higher in the past and lower in the future, with different contributions to the total (average) energy density at a point dropping at different rates (this is the "equation of state" for each of radiation, baryons, neutrinos, dark matter, ...), but they all drop away towards nothing in the far future. We can then think of where stress-energy goes at an average point. For freely falling baryons, almost nothing interferes with the whole of the stress-energy flowing from (microsecond-before,0,0,0) to (now,0,0,0) to (microsecond-after,0,0,0). There's some cosmic mircowaves and neutrinos that have a tiny ghost of a chance of transferring in some momentum via scattering at each point, but that falls away when we consider the average across each of these three 3d spaces. Flipping things back around, while a "mote" of the baryon gas stays "at the integers" as we add more and more digits after the decimal point as space expands, each time we add digits we get more dark energy fluid "motes". If we change coordinates, the coordinate-distance between "motes" of the fluid grows with the expansion, e.g. as the distance between these proxies for galaxy clusters goes from 1 to 10 to 100 to ... the 9, 99, ... has "new" motes of dark energy. Given this it is straightforward to treat some aspects of the expansion as another fluid with an energy density that is the same at every point in every space. It does not dilute away like the others. It imposes a tension ("negative pressure") on the other sources of energy-density. If we think of a single point in one of these 3d spaces as being imprisoned within a tiny six-sided cubical cell, we can track the flow of momentum through each (pair of) face(s) of the cell. At very early times radiation flowing through the cell dominates. The inflow is tracked as the normal stress <https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Fi.ytimg.com%2Fvi%2FVpaEsqjzaGY%2Fmaxresdefault.jpg&f=1&nofb=1&ipt=58d23f7a57028b81bca9ddbc5fe0c863efa8695dd286650c23ae4c73c6ed7445&ipo=images https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2F...> on each face. When the normal stress is identical on all six faces (or spherically symmetrical if we switch from a cube to a sphere), we call that pressure. Negative pressure is just flipping the arrows around. We can call that "tension". Colloquially we're interested in how much the pressure changes the energy level of the imprisoned matter. In general, large positive pressure leads to the imprisoned matter becoming more energetic. Large negative pressure would lead to the imprisoned matter becoming less energetic. "Large" here is relative to the energy-density within the cell, and varies by component ("equation of state" again). In the comsological frame, freely-falling imprisoned matter (baryons, dark matter) in a cell at (t,1,1,1) will thus cool with the expansion across (t',1,1,1), (t'',1,1,1) and so forth, with the energy sucked out by the constant outward tension. > 16 simultaneous partial differential equations You can start with understanding the stress-energy tensor. This is it laid out in a 4x4 matrix form <https://en.wikipedia.org/wiki/Stress%E2%80%93energy_tensor#/media/File:StressEnergyTensor_contravariant.svg https://en.wikipedia.org/wiki/Stress%E2%80%93energy_tensor#/...>. The indices running 0,1,2,3 correspond to the timelike dimension and the three spacelike ones. Each element of the matrix has two indices i and j (e.g. for T^00 in the top left, we have i=0, j=0) indicating the "comesinfrom" and "goesoutto" directions. Energy pouring in and staying in is the orange column. Energy already there and staying put is the top left. Let's use spherical coordinates and call the 1 direction "in/out", i.e., described by the radial coordinate. We'll place our cell of interest microscopically displaced radially from the spherical coordinate origin. If we were in a dense object like the core of a planet or star, T^11 would be dominated by the inwards flow of inwards-momentum and the reaction-pressure of outwards-momentum flowing outwards. In high-mass stars' cores, this number will dominate all the others in the stress-energy tensor. Also in general T^ij, i=j, i!=0 (the green bar) will not be completely identical. However, if we're in a cosmological setting (deep inter-galaxy-cluster space), T^11 is [a] small, [b] it's the same as T^22 and T^33, and [c] they are interpretable as the flow of energy-momentum out of the cell. In the very very far future, T^00 drops to zero, and T^ii, i!=0 (despite being small) dominates. Another difference here is that in the stellar core positive pressure case, T^11 is not a constant. However, if we got rid of all possible radiation pressure and the like, in the resulting cosmological vacuum T^11 would be a constant (and identical to T^22 and T^33). This is an interpretation that depends on our choice of viewpoint (that of a freely floating low-mass observer who feels only the expansion and not attractive influences from dense matter, because all matter is completely evenly smeared out). The interpretation does not hold up well as we change our point of view (e.g. to a relativistic observer, to a different set of coordinates, to an observer who is close to or part of a self-gravitating mass overdensity). Consequently it is probably better to start with the idea that dark energy is the Cosmological Constant (until this possibility is disproven, which has not happened yet). It is simply a constant of nature, like the speed of light or like the charge of an electron. Where does the constant come from? Who knows! Sometimes it is convenient to think of this constant as if it were a substance with appropriate properties, or as if it were "the cost of empty space" (vacuum energy). However it's also possible to be misled by this. It's a scalar quantity, and it has an exact relationship to a tensor quantity (the metric). Scalars and tensors are generally covariant, so we can always make that pairing work for any possible observer, even e.g. an ultrarelativistic cosmic ray or a photon or a relativistic compact object like a black hole. Finally, the reason for "sometimes" is: while the total tensor value of T is the same for everyone, the value of the individual components of the tensor depends on the frame of reference. One of the sometimeses is the very early universe when radiation pressure is extremely important for smoothing out temperature and density differences; it is natural to want to do accounting of the expansion as an offset against that radiation pressure instead of the "truer picture" of the radiation pressure falling because the radiation is diluted and de-energized (redshifted) by the early expansion.
sudhirj 4y ago
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?
- Sharlin 4y ago
  Energy is mass, mass is energy. E=mc^2, remember? Mass is not in general conserved. Every second every main-sequence star in the universe converts untold millions of tons of mass to energy. But in general relativity even energy is not conserved because the universe is expanding.
- mlatu 4y ago
  energy is accelerated mass, so i guess the simple answer to your last question is yes while your first question doesnt make much sense. not a physicist though..
  - sgsag33 4y ago
    That`s just wrong. If e = mc^2 THAN m is NOT accelerated e...
    - boomboomsubban 4y ago
      They said e is accelerated m, which is broadly what the equation shows.
      - maze-le 4y ago
        Not really, c^2 has the unit of velocity squared, not acceleration: [c^2] = [(v^2/t^2)] != [(v/t^2)] = [a] We can also choose natural units where c==1, which leads directly to e==m
        boomboomsubban 4y ago
        I took "accelerated" to mean at a certain speed, like in the sentence "we accelerated to 1 meter per second," not acceleration itself.
siddiqi64 4y ago
Informative article thanks
deleted 4y ago
[deleted]
blatant303 4y ago
> 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.” 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. https://hal.science/hal-03835483/document https://hal.science/hal-03835483/document edit : the article talks about a k factor of 3, not sure whether it matches Petit's plugstar redshift factor of 3.
- T-A 4y ago
  I've never heard of Petit or plugstars, but a quick look at the linked document shows that he expects light emitted from them to be redshifted by a factor 3. This is utterly unrelated to the k factor in Eq. 1 of https://iopscience.iop.org/article/10.3847/2041-8213/acb704 https://iopscience.iop.org/article/10.3847/2041-8213/acb704 which is the cosmological coupling strength.
denton-scratch 4y ago
I read the article, but not the paper. The article's quite popsci, I think. No doubt I misunderstood, but it sounds like circular reasoning: * Cosmic expansion of spacetime causes expansion of black holes * An expanded black hole must have greater mass * Increasing mass of black holes results in cosmic expansion of spacetime 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.
- deleted 4y ago
  [deleted]
- dav_Oz 4y ago
  Citing from the paper [0] > Einstein’s equations, however, give no prescription for converting the actual, position-dependent, distribution of stress-energy observed at late times into a position-independent source. Croker & Weiner (2019) resolved this averaging ambiguity, showing how the Einstein–Hilbert action gives the necessary relation between the actual distribution of stress- energy and the source for the RW model. A consequence of this result is that relativistic material, located anywhere, can become cosmologically coupled to the expansion rate. This has implications for singularity-free BH models, such as those with vacuum energy interiors. The stress-energy within BHs like these, and therefore their gravitating mass, can vary in time with the expansion rate. The effect is analogous to the cosmological photon redshift, but generalized to timelike trajectories. So, yes two different things are presupposed through refined cosmological models: 1) singularity-free black holes limited by vacuum energy and 2) relativistic mass becoming cosmologically coupled to the expansion rate of the universe. In that case BHs can so-to-speak be "red-shifted" by expanding (empty) space via vacuum-energy and gain mass (> stellar remnant k=3 BHs are the astrophysical origin for the late-time accelerating expansion of the universe.) One thing to keep in mind, GR as geometrical modeling (field equations) of the universe is at its heart reciprocal. Wheeler[1] captured this succinctly in the now-famous statement: Space-time tells matter how to move; matter tells space-time how to curve. [0]https://iopscience.iop.org/article/10.3847/2041-8213/acb704/pdf https://iopscience.iop.org/article/10.3847/2041-8213/acb704/... [1]https://aapt.scitation.org/doi/abs/10.1119/1.16710?journalCode=ajp https://aapt.scitation.org/doi/abs/10.1119/1.16710?journalCo...
miq333l 4y ago
Looking at the coupling strength value range it just seems like the coupling strength will be equal to pi. I have no evidence here just a hunch.
subless 4y ago
Other related thread: https://news.ycombinator.com/item?id=34818078 https://news.ycombinator.com/item?id=34818078 My comment on that thread: https://news.ycombinator.com/item?id=34819406 https://news.ycombinator.com/item?id=34819406
- ta988 4y ago
  No because we have tools that can measure those energy levels and we don't see "invisible things" with them. For the second part I have no idea, but that would be a fun thing to discover, universes just feeding into each other.
- PeterWhittaker 4y ago
  The UMich article contains a quote that I think argues that there is nothing “on the other side” of black holes that could be the birth of a new universe: “If cosmological coupling is confirmed, it would mean that black holes never entirely disconnect from our universe, that they continue to exert a major influence on the evolution of the universe into the distant future” Tarlé said. That suggests to me that popular notion that black holes are an entry point to a wormhole leading to a new place would be unfounded.
hilbert42 4y ago
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? After all, vacuum energy/zero point energy/ZPE is a quantum phenomenon, albeit not that well understood.
- PeterWhittaker 4y ago
  From a physics POV, perhaps. Unfortunately, and I wish I could find the great illustration of this I stumbled across a few years ago, the two theories, QM and GR, are also separated by a mathematical gulf: the dominant maths used in each are so far apart on math’s “evolutionary tree”, if you will, that it will take considerable work to bring them together, even with alignment of the underlying physics. The mental image I have, based on that lost but amazing illustration, is the difference between mammals and birds: sure, they’re both warm blooded, largely social bilaterally symmetrical vertebrates, but they’re awfully far apart.
  - hilbert42 4y ago
    I understand your point and your analogy of mammals and birds and the mathematical gulf, it's a good one. Damn shame you've lost reference to that illustration, I'd love to see it. Embedded in my comment was the thought that if the empirical evidence for this observation was overwhelming then this tight and specific coupling between QM and GR would be so embarrassing that mathematicians would have no option but to significantly up the ante (and also this new evidence may bring a fresh approach). We've seen this leapfrogging between math and physics many times before, Newton/calculus, Hamilton/quaternions, Galois/group theory, etc. Wishful thinking perhaps, but the standoff/gulf has to collapse eventually. It'd be nice if this observation was the impetus.
PaulHoule 4y ago
I have to admit I don't get it. 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!) 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. Needless to say, none of the above is expected to work.
machina_ex_deus 4y ago
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. 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.
scotty79 4y ago
Does anyone know where I could read about the model of a blackhole that has vacuum energy inside instead of singularity?

It replaces singularity at the center of Black holes and brings in Vacuum Energy in its place. But I thought Vaccum Energy theory isn't proven in practice, in the sense there's huge discrepancy between theoretical value vs observed. Anyway it would be interesting to watch where this goes.

nathan_compton 4y ago

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?

negativelambda 4y ago

The guardian also has an article about this: https://www.theguardian.com/science/2023/feb/15/black-holes-contain-dark-energy-that-drive-expansion-of-universe https://www.theguardian.com/science/2023/feb/15/black-holes-... But if you’re interested in the details, the journal article is here: https://iopscience.iop.org/article/10.3847/2041-8213/acb704 https://iopscience.iop.org/article/10.3847/2041-8213/acb704

jachin 4y ago

[flagged]

negativelambda 4y ago
That reminds me of the Red Dwarf episode: https://youtu.be/SqI41N4WGPM https://youtu.be/SqI41N4WGPM
- dylan604 4y ago
  Non-sequitor, but I grew up watching Red Dwarf with BBC on PBS. I never had a cat as a kid, so that character was totally bizarre to me. Now after being a cat "caretaker", I think owner is not quite right, I totally understand that character. This made rewatching that series so much more enjoyable. The story of his audition is still one of my favorites: "On television, John-Jules is best known for his portrayal of Cat and Cat's geeky alter ego Dwayne Dibbley in the British comedy series Red Dwarf. He obtained the part of Cat by turning up half an hour late for his audition, dressed in his father's old zoot suit. He was unaware that he was late and hence did not appear at all concerned about it. The producers immediately decided he was cool enough to be "the Cat"." --wikipedia
Nevermark 4y ago
I hereby coin the linkage between Dark Energy and Dark Stars ... "Dark Synergy"! Unfortunately, the Dark is scary, as far as I can tell. If black holes masses keep increasing, and the universe keeps accelerating in size, we end by stretch of by crush. Or does one of these effects ever win? Is there any hope for a middle case where we get through?

mtlmtlmtlmtl 4y ago

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?

jwuphysics 4y ago

This biggest caveat is mentioned in the ApJL paper [0] introduction: > 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). I think there are several observational effects that may obfuscate the interpretation -- but I also haven't read these papers in great detail. 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. [0] https://iopscience.iop.org/article/10.3847/2041-8213/acb704 https://iopscience.iop.org/article/10.3847/2041-8213/acb704

xqcgrek2 4y ago
Are those two effects big enough to make a false signal as big as the purported signal? They seem like relatively minor annoyances.
- _0w8t 4y ago
  I also think that the estimated growth was too big to be caused by such systematic errors. On the other hand we do not have models of a galaxy evolution based on solving equations of General Relativity. Typically the assumption is that Newtonian gravity with minimal relativistic corrections should be enough. But there is no proof that it is so. Moreover, there were relatively recent papers that showed that better accounting for General Relativity could be enough to explain rotational curves for Galaxies without any notion of Dark Matter and that the need for Dark Matter was simply ab artifact of the assumption that Newtonian gravity can be used at the galaxy scale. Then there are speculations that electromagnetic forces do play role at the galaxy scale affecting the rate of evolution of galaxies. So it can be that the observed discrepancy in the growth of Black Holes caused by holes in galaxy evolution models, not by the proposed new effect.

spartanatreyu 4y ago

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. I also can't wait for the Space Time video on this once it had enough peer review to report on.

mindcrime 4y ago
I can't wait for the inevitable Sabine Hofstadter video that either call out an obvious flaw... I'm guessing you meant to say Sabine Hossenfelder[1]? [1]: https://en.wikipedia.org/wiki/Sabine_Hossenfelder https://en.wikipedia.org/wiki/Sabine_Hossenfelder
- spartanatreyu 4y ago
  Yes your right, I typed the name into google to get it to autocorrect for me (I hadn't had enough caffeine yet) and google autoco-wrecked me instead.
- Eupraxias 4y ago
  I made the same mistake once myself, but feel that Sabine should feel honoured to be slipped for Douglas.
  - mindcrime 4y ago
    Fair point! Now for somebody to slip and call her Sabine Hasselhoff...
    - sohkamyung 4y ago
      I guess this is in reference to some videos she made of herself singing? :-)
      - 1over137 4y ago
        And because she's German, and the Germans love David Hasselhoff. :)

Aperocky 4y ago

So increasing mass of black holes ... drive galaxies apart? 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! 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. How the patch notes might have looked like: * 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. * This black hole feature is working very pleasantly, putting black hole seeds in center of galaxies so they can grow faster. * 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 ... 3893 commits later * who did the black hole space time stretch? the galaxies are flying apart and heat death is upon the simulation! Reopening #TODO.

ilrwbwrkhv 4y ago
Hopefully on-call is solid
- Aperocky 4y ago
  bad news: we're actually alpha and this eon's intern just submitted their first commit.
  - steve_mcdougall 4y ago
    @Jehovah just circling back to some interesting decisions you made previously. Please pop into my office when you have some time to discuss.
    - deleted 4y ago
      [deleted]

bobse 4y ago

>dark energy When will this meme die?

jfengel 4y ago
When something better comes along to replace it.
- bobse 4y ago
  DARK GOD
- JKCalhoun 4y ago
  I don't know, can't you be skeptical of a thing without having a better alternative?
  - smolder 4y ago
    Yes.
  - jfengel 4y ago
    You can. But thinking it's a "meme" that should "die" is not being skeptical. It's the best current explanation, and an uninformed dislike is not to be mistaken for an understanding of its limitations.

dmbche 4y ago

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? Super interesting papers!

leereeves 4y ago
Unfortunately the article seems to gloss over that point with just one sentence: > The conclusion is profound: Croker and Weiner had already shown that if k is 3, then all black holes in the universe collectively contribute a nearly constant dark energy density, just like measurements of dark energy suggest. That sentence contains a link to a paper[1] that's highly technical and beyond my understanding of physics, but concludes: > A population of such stellar-collapse remnants can shift in energy $\propto a^3$ while diluting in number density $\propto 1/{a}^{3}$. The population-averaged energy density is then effectively constant and readily produces the observed ${{\rm{\Omega }}}_{{\rm{\Lambda }}}$. which matches the claim in the article. But to understand why, I guess we'd have to learn general relativity to understand the math in that paper. 1: https://iopscience.iop.org/article/10.3847/1538-4357/ab32da#apjab32das5 https://iopscience.iop.org/article/10.3847/1538-4357/ab32da#...

transfire 4y ago

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.)

hoseja 4y ago

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?

college_physics 4y ago

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. [0] https://iopscience.iop.org/article/10.3847/1538-4357/ab32da https://iopscience.iop.org/article/10.3847/1538-4357/ab32da

kiviuq 4y ago

According to Einstein matter equals energy. So how is it possible to discern between dark energy and dark matter. They could be indistinguishable, no? do you think this will still hold DE=DM*cˆ2

Sharlin 4y ago
They are entirely different things, only related by the word “dark”. Dark energy is “negative” energy in the sense that it drives expansion rather than slowing it down. Its energy density is also constant, meaning it is not diluted by expansion unlike matter (dark or not) and normal energy. It seems to be a fundamental property of spacetime.
ben_w 4y ago
The reason they even came up with the idea is because they're distinguishable. Unfortunately, my mental model is merely one step up from PopScience articles, so the following probably has more holes than a doughnut carved out of Swiss cheese: Dark matter was first noticed in the unexpected relationship between the orbital speed of stars in galaxies and their distance from the centre. This has since been improved by the direct observation of gravitational lensing, which also shows its not "simply" gravity falling off at a different rate that 1/r^2 at these scales as the lensing isn't always inside the galaxies e.g. when two collide. Dark matter behaves like it doesn't interact with anything much, not even itself. On the other hand, dark energy was originally suggested by Einstein as a fudge factor to make the universe static on large scales, something he later dropped in embarrassment when Hubble expansion was found, only for it to come back when people noticed the expansion seemed to be accelerating. Dark energy, for maths reasons I don't really understand[0], acts like negative pressure even though it's positive energy, which occupies all space evenly and therefore has an effect directly proportional to distance, not inverse squared like gravity. [0] 16 simultaneous partial differential equations whose contents can vary throughout a 3+1 spacetime is something I have yet to even attempt to play with
- raattgift 4y ago
  > Dark energy, for maths reasons I don't really understand[0], acts like negative pressure even though it's positive energy First, let's understand a bit about the cosmological frame: it lets us consider the universe as 3-dimension-of-space ordered by a "scale factor" dimension of time. The coordinates of each 3d space are Euclidean, but the coordinates don't line up exactly between different scale factors. Colloquially, the coordinates expand with the expansion of space, or equivalently the space between coordinates grows over time. You could think of it this way: if at some early point we label every point in space with an integer, in the future of that point we have to add new labels between the integers. If we add in a pair low-mass freely-falling test matter at the time when everything is labelled with an integer, e.g. at point (1,1,1) and (2,1,1), then they stay at those coordinates even as more and more labelled (with non-integer) space appears between them. To this we add a set of gasses, dusts, or fluids representing radiation, ordinary nonrelativistic matter, and maybe others (e.g. relativistic dark matter (e.g. neutrinos), non-relativistic dark matter ("cold dark matter"/"particle dark matter")). Again, any "mote" of the ordinary matter dust stays at the same coordinate forever. Rather than coping with the "motes" of radiation not staying put, we average every point in space and see there is some quantity of matter (a mote, or a fraction thereof), some quantity of radiation (a mote, or a fraction thereof), some quantity of dark matter, and so forth. The dusts dilute away because more and more space appears between each original coordinate. In our averaging picture, we get a smaller and smaller fraction of a mote at eacn point on average as the universe expands. This is the essence of the Friedmann-Lemaître-Robertson-Walker model that is the standard cosmology. The view here is that of boring old observers freely floating in deep inter-galaxy-cluster space. That leads to (from that view point) concrete calculations of the various contributions to the averaged energy-density at each point in space at a particular scale factor ("at a given age of the universe"). In general, that figure is higher in the past and lower in the future, with different contributions to the total (average) energy density at a point dropping at different rates (this is the "equation of state" for each of radiation, baryons, neutrinos, dark matter, ...), but they all drop away towards nothing in the far future. We can then think of where stress-energy goes at an average point. For freely falling baryons, almost nothing interferes with the whole of the stress-energy flowing from (microsecond-before,0,0,0) to (now,0,0,0) to (microsecond-after,0,0,0). There's some cosmic mircowaves and neutrinos that have a tiny ghost of a chance of transferring in some momentum via scattering at each point, but that falls away when we consider the average across each of these three 3d spaces. Flipping things back around, while a "mote" of the baryon gas stays "at the integers" as we add more and more digits after the decimal point as space expands, each time we add digits we get more dark energy fluid "motes". If we change coordinates, the coordinate-distance between "motes" of the fluid grows with the expansion, e.g. as the distance between these proxies for galaxy clusters goes from 1 to 10 to 100 to ... the 9, 99, ... has "new" motes of dark energy. Given this it is straightforward to treat some aspects of the expansion as another fluid with an energy density that is the same at every point in every space. It does not dilute away like the others. It imposes a tension ("negative pressure") on the other sources of energy-density. If we think of a single point in one of these 3d spaces as being imprisoned within a tiny six-sided cubical cell, we can track the flow of momentum through each (pair of) face(s) of the cell. At very early times radiation flowing through the cell dominates. The inflow is tracked as the normal stress <https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Fi.ytimg.com%2Fvi%2FVpaEsqjzaGY%2Fmaxresdefault.jpg&f=1&nofb=1&ipt=58d23f7a57028b81bca9ddbc5fe0c863efa8695dd286650c23ae4c73c6ed7445&ipo=images https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2F...> on each face. When the normal stress is identical on all six faces (or spherically symmetrical if we switch from a cube to a sphere), we call that pressure. Negative pressure is just flipping the arrows around. We can call that "tension". Colloquially we're interested in how much the pressure changes the energy level of the imprisoned matter. In general, large positive pressure leads to the imprisoned matter becoming more energetic. Large negative pressure would lead to the imprisoned matter becoming less energetic. "Large" here is relative to the energy-density within the cell, and varies by component ("equation of state" again). In the comsological frame, freely-falling imprisoned matter (baryons, dark matter) in a cell at (t,1,1,1) will thus cool with the expansion across (t',1,1,1), (t'',1,1,1) and so forth, with the energy sucked out by the constant outward tension. > 16 simultaneous partial differential equations You can start with understanding the stress-energy tensor. This is it laid out in a 4x4 matrix form <https://en.wikipedia.org/wiki/Stress%E2%80%93energy_tensor#/media/File:StressEnergyTensor_contravariant.svg https://en.wikipedia.org/wiki/Stress%E2%80%93energy_tensor#/...>. The indices running 0,1,2,3 correspond to the timelike dimension and the three spacelike ones. Each element of the matrix has two indices i and j (e.g. for T^00 in the top left, we have i=0, j=0) indicating the "comesinfrom" and "goesoutto" directions. Energy pouring in and staying in is the orange column. Energy already there and staying put is the top left. Let's use spherical coordinates and call the 1 direction "in/out", i.e., described by the radial coordinate. We'll place our cell of interest microscopically displaced radially from the spherical coordinate origin. If we were in a dense object like the core of a planet or star, T^11 would be dominated by the inwards flow of inwards-momentum and the reaction-pressure of outwards-momentum flowing outwards. In high-mass stars' cores, this number will dominate all the others in the stress-energy tensor. Also in general T^ij, i=j, i!=0 (the green bar) will not be completely identical. However, if we're in a cosmological setting (deep inter-galaxy-cluster space), T^11 is [a] small, [b] it's the same as T^22 and T^33, and [c] they are interpretable as the flow of energy-momentum out of the cell. In the very very far future, T^00 drops to zero, and T^ii, i!=0 (despite being small) dominates. Another difference here is that in the stellar core positive pressure case, T^11 is not a constant. However, if we got rid of all possible radiation pressure and the like, in the resulting cosmological vacuum T^11 would be a constant (and identical to T^22 and T^33). This is an interpretation that depends on our choice of viewpoint (that of a freely floating low-mass observer who feels only the expansion and not attractive influences from dense matter, because all matter is completely evenly smeared out). The interpretation does not hold up well as we change our point of view (e.g. to a relativistic observer, to a different set of coordinates, to an observer who is close to or part of a self-gravitating mass overdensity). Consequently it is probably better to start with the idea that dark energy is the Cosmological Constant (until this possibility is disproven, which has not happened yet). It is simply a constant of nature, like the speed of light or like the charge of an electron. Where does the constant come from? Who knows! Sometimes it is convenient to think of this constant as if it were a substance with appropriate properties, or as if it were "the cost of empty space" (vacuum energy). However it's also possible to be misled by this. It's a scalar quantity, and it has an exact relationship to a tensor quantity (the metric). Scalars and tensors are generally covariant, so we can always make that pairing work for any possible observer, even e.g. an ultrarelativistic cosmic ray or a photon or a relativistic compact object like a black hole. Finally, the reason for "sometimes" is: while the total tensor value of T is the same for everyone, the value of the individual components of the tensor depends on the frame of reference. One of the sometimeses is the very early universe when radiation pressure is extremely important for smoothing out temperature and density differences; it is natural to want to do accounting of the expansion as an offset against that radiation pressure instead of the "truer picture" of the radiation pressure falling because the radiation is diluted and de-energized (redshifted) by the early expansion.

sudhirj 4y ago

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?

Sharlin 4y ago
Energy is mass, mass is energy. E=mc^2, remember? Mass is not in general conserved. Every second every main-sequence star in the universe converts untold millions of tons of mass to energy. But in general relativity even energy is not conserved because the universe is expanding.
mlatu 4y ago
energy is accelerated mass, so i guess the simple answer to your last question is yes while your first question doesnt make much sense. not a physicist though..
- sgsag33 4y ago
  That`s just wrong. If e = mc^2 THAN m is NOT accelerated e...
  - boomboomsubban 4y ago
    They said e is accelerated m, which is broadly what the equation shows.
    - maze-le 4y ago
      Not really, c^2 has the unit of velocity squared, not acceleration: [c^2] = [(v^2/t^2)] != [(v/t^2)] = [a] We can also choose natural units where c==1, which leads directly to e==m
      - boomboomsubban 4y ago
        I took "accelerated" to mean at a certain speed, like in the sentence "we accelerated to 1 meter per second," not acceleration itself.

siddiqi64 4y ago

Informative article thanks

deleted 4y ago

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blatant303 4y ago

> 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.” 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. https://hal.science/hal-03835483/document https://hal.science/hal-03835483/document edit : the article talks about a k factor of 3, not sure whether it matches Petit's plugstar redshift factor of 3.

T-A 4y ago
I've never heard of Petit or plugstars, but a quick look at the linked document shows that he expects light emitted from them to be redshifted by a factor 3. This is utterly unrelated to the k factor in Eq. 1 of https://iopscience.iop.org/article/10.3847/2041-8213/acb704 https://iopscience.iop.org/article/10.3847/2041-8213/acb704 which is the cosmological coupling strength.

denton-scratch 4y ago

I read the article, but not the paper. The article's quite popsci, I think. No doubt I misunderstood, but it sounds like circular reasoning: * Cosmic expansion of spacetime causes expansion of black holes * An expanded black hole must have greater mass * Increasing mass of black holes results in cosmic expansion of spacetime 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.

deleted 4y ago
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dav_Oz 4y ago
Citing from the paper [0] > Einstein’s equations, however, give no prescription for converting the actual, position-dependent, distribution of stress-energy observed at late times into a position-independent source. Croker & Weiner (2019) resolved this averaging ambiguity, showing how the Einstein–Hilbert action gives the necessary relation between the actual distribution of stress- energy and the source for the RW model. A consequence of this result is that relativistic material, located anywhere, can become cosmologically coupled to the expansion rate. This has implications for singularity-free BH models, such as those with vacuum energy interiors. The stress-energy within BHs like these, and therefore their gravitating mass, can vary in time with the expansion rate. The effect is analogous to the cosmological photon redshift, but generalized to timelike trajectories. So, yes two different things are presupposed through refined cosmological models: 1) singularity-free black holes limited by vacuum energy and 2) relativistic mass becoming cosmologically coupled to the expansion rate of the universe. In that case BHs can so-to-speak be "red-shifted" by expanding (empty) space via vacuum-energy and gain mass (> stellar remnant k=3 BHs are the astrophysical origin for the late-time accelerating expansion of the universe.) One thing to keep in mind, GR as geometrical modeling (field equations) of the universe is at its heart reciprocal. Wheeler[1] captured this succinctly in the now-famous statement: Space-time tells matter how to move; matter tells space-time how to curve. [0]https://iopscience.iop.org/article/10.3847/2041-8213/acb704/pdf https://iopscience.iop.org/article/10.3847/2041-8213/acb704/... [1]https://aapt.scitation.org/doi/abs/10.1119/1.16710?journalCode=ajp https://aapt.scitation.org/doi/abs/10.1119/1.16710?journalCo...

miq333l 4y ago

Looking at the coupling strength value range it just seems like the coupling strength will be equal to pi. I have no evidence here just a hunch.

subless 4y ago

Other related thread: https://news.ycombinator.com/item?id=34818078 https://news.ycombinator.com/item?id=34818078 My comment on that thread: https://news.ycombinator.com/item?id=34819406 https://news.ycombinator.com/item?id=34819406

ta988 4y ago
No because we have tools that can measure those energy levels and we don't see "invisible things" with them. For the second part I have no idea, but that would be a fun thing to discover, universes just feeding into each other.
PeterWhittaker 4y ago
The UMich article contains a quote that I think argues that there is nothing “on the other side” of black holes that could be the birth of a new universe: “If cosmological coupling is confirmed, it would mean that black holes never entirely disconnect from our universe, that they continue to exert a major influence on the evolution of the universe into the distant future” Tarlé said. That suggests to me that popular notion that black holes are an entry point to a wormhole leading to a new place would be unfounded.

hilbert42 4y ago

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? After all, vacuum energy/zero point energy/ZPE is a quantum phenomenon, albeit not that well understood.

PeterWhittaker 4y ago
From a physics POV, perhaps. Unfortunately, and I wish I could find the great illustration of this I stumbled across a few years ago, the two theories, QM and GR, are also separated by a mathematical gulf: the dominant maths used in each are so far apart on math’s “evolutionary tree”, if you will, that it will take considerable work to bring them together, even with alignment of the underlying physics. The mental image I have, based on that lost but amazing illustration, is the difference between mammals and birds: sure, they’re both warm blooded, largely social bilaterally symmetrical vertebrates, but they’re awfully far apart.
- hilbert42 4y ago
  I understand your point and your analogy of mammals and birds and the mathematical gulf, it's a good one. Damn shame you've lost reference to that illustration, I'd love to see it. Embedded in my comment was the thought that if the empirical evidence for this observation was overwhelming then this tight and specific coupling between QM and GR would be so embarrassing that mathematicians would have no option but to significantly up the ante (and also this new evidence may bring a fresh approach). We've seen this leapfrogging between math and physics many times before, Newton/calculus, Hamilton/quaternions, Galois/group theory, etc. Wishful thinking perhaps, but the standoff/gulf has to collapse eventually. It'd be nice if this observation was the impetus.

PaulHoule 4y ago

I have to admit I don't get it. 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!) 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. Needless to say, none of the above is expected to work.

machina_ex_deus 4y ago

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. 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.

scotty79 4y ago

Does anyone know where I could read about the model of a blackhole that has vacuum energy inside instead of singularity?