[HN Gopher] Einstein and his peers were resistant to black holes
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Einstein and his peers were resistant to black holes
Author : tigerlily
Score : 69 points
Date : 2024-06-28 03:50 UTC (19 hours ago)
(HTM) web link (www.bbc.com)
(TXT) w3m dump (www.bbc.com)
| IIAOPSW wrote:
| Given he was clearly convinced in the end by sound arguments, was
| it really irrational or was he just a hard sell for good reasons?
| jerf wrote:
| I think there's plenty of reasons to be a hard sell on
| relativity's take on black holes. After all, it's still a
| plenty hard sell today. The evidence that things that looks
| like black holes on the _outside_ exist is pretty solid, but
| the _evidence_ we have about the insides is zero. I don 't
| particularly "believe" in the relativity take on black holes
| either, which is to say, I have very high confidence that a
| real and effectively-correct theory of quantum gravity will
| remove the singularities.
|
| I'd _love_ to pull off the trick of being extremely easy to
| convince about true things and _only_ true things, and being
| very stubborn about everything else, but that 's basically
| epistemologically begging the question. It's too much to ask of
| anyone.
| zeroxfe wrote:
| > I have very high confidence that a real and effectively-
| correct theory of quantum gravity will remove the
| singularities.
|
| What gives you this confidence?
| vecter wrote:
| The general belief that singularities are "unphysical" and
| reflect a flaw in our models than actual reality. Hard to
| prove definitely right now of course.
| hparadiz wrote:
| I always thought the concept of a singularity here was
| just to make the math slightly simpler. That is to say
| that a black hole is still a spherical body with a set
| diameter. We just can't see it so there's no way to
| verify other than the fact that we can see the border of
| the event horizon.
| atombender wrote:
| As far as I know, that very much isn't the case. The
| singularity is a result of the math, not a trick to
| simplify it.
|
| My understanding is that many researchers do think it's a
| "placeholder" representing our lack of insight into how
| physics behave at those scales, and not a real physical
| phenomenon, and that it will one day be possible to work
| past it. I believe Kerr and Penrose (both of whom did
| some of the most foundational work on black holes)
| believe it's a mathematical artifact.
| hparadiz wrote:
| My random thoughts on this:
|
| - Is the math referring to the center of gravity as the
| singularity? Because even a sub black hole mass object
| would have that.
|
| - Why is there an assumption that just after a mass
| becomes a black hole the matter inside it suddenly
| compresses further when the actual gravity of the object
| has only slightly increased?
|
| - Is there a maximum density of matter in the universe
| and if the black hole even reaches that?
|
| - Wouldn't you need that number to be infinite if the
| black hole itself is infinitely small?
|
| - If the black hole does have a mass inside it... Do the
| light particles trapped inside the black hole form a
| blanket around the existing matter?
| vlovich123 wrote:
| All we know is that we've made a lot of crazy predictions
| about the structure and behavior of black holes well
| before we measured them and so far they've aligned
| remarkably close to the predictions. If there is a
| difference, it's about the interior not how it shows up
| in our universe. And since we can never see inside the
| black hole, any alternative model would have to better
| explain some phenomena our existing models can't or be
| even easier than relativity and explain the same things.
| We know string theory is hard to make consistent and it
| struggles to create falsifiable experiments. I would bet
| on relatively remaining a very very long time until we
| figure out how to unify quantum and relativity.
| zmgsabst wrote:
| Alternative:
|
| Quantum theories arise because the singularities in black
| holes create a topological regime within their vicinity --
| and for SMBs, that's a whole galaxy.
|
| I think it's interesting that different people feel different
| things are "natural".
| datavirtue wrote:
| In layman's terms, isn't the take that the area of a black
| hole is devoid of space? Therefore you can never see or
| measure it except for forces generated by it within our
| space.
| ajkjk wrote:
| The claim of general relativity is that a black hole is a
| singularity in spacetime, meaning that space effectively
| "ends" there. A very crude model would be cutting a hole
| out of fabric and then sewing the circle up into a point.
| The area of the hole is "gone" --- it's not like it's there
| and you can't see it, it's just _not there_. I guess that
| it is what you mean by "devoid of space".
|
| Then the rest of the fabric is bent in weird ways around
| the fact that there's a chunk missing, which in physics
| manifests as as everything being pulled towards it (and
| there is a point, the event horizon, at which things are no
| longer possible to interact with, like you're too deep in
| the hole to get out again.
| mistermann wrote:
| > It's too much to ask of anyone.
|
| Ternary logic is available ( _physically_ at least).
| ajkjk wrote:
| I see no epistemic problem with a singularity existing. After
| all electron are singularities in the EM field, of a sort.
| Why shouldn't a lot of electrons together form a giant
| singularity?
| Analemma_ wrote:
| I'm not at all an expert in this, but my limited
| understanding is that electrons are only "singularities" in
| classical EM; in quantum field theory they're just solitons
| of the underlying quantum field and can be analyzed with no
| infinities present. We haven't found a QFT equivalent for
| gravity yet, but I think the broad consensus is that the
| gravitational singularities will disappear once we do.
| antognini wrote:
| Truth be told, we don't really know that electrons are
| singularities in the EM field. Classically that's the case,
| of course. But in QFT, as you start to probe to shorter
| distances (and higher energies), our theories eventually
| break down because gravitational effects cannot be ignored.
| (For instance, how do you describe the EM field at
| distances shorter than a Planck length? The energies needed
| to probe to that limit would collapse the system into a
| black hole.)
| bmitc wrote:
| That doesn't really follow, because it seems that people were
| and are wanting black holes to be something else that they
| are both not observed to be and not described by any theory
| of them.
|
| Also, I think it gets lost in physics that theories are
| _models_ of reality. They are not reality themselves. General
| relativity is about as good as a model gets. Alongside the
| standard model, it 's one of the most tested models around.
|
| A singularity has a meaning in physics in terms of math,
| which is dividing by zero or something approaching zero in
| the denominator. A singularity has a physically modeled
| aspect in that it's the name assigned to whatever becomes of
| the matter that gets squished down. A black hole is
| effectively not a thing in itself but rather an effect of
| what happens when mass is squeezed beyond all known limits.
|
| What's inside a black hole is not the only thing in the
| universe we can't see. The actual universe is far bigger than
| the visible universe, but we can't see outside of the visible
| universe due to how light works. So it basically doesn't even
| matter what's going on there. The question is if anything
| happening at the boundaries can tell us something about that
| which we can't see. It doesn't make sense to dismiss what we
| observe on the outside based upon what we literally cannot
| know of the inside.
|
| And after all, general relativity is a classical theory. Is
| it _really_ all that "weird"? It all feels somewhat
| mechanical and natural as you start learning it and turn off
| your biased intuition.
| burnished wrote:
| Read the article, resistance came from a sense of personal
| repugnance and concluded in the form of personal attacks. It
| was irrational.
| empath75 wrote:
| There was one insulting dismissal of one physicists grasp of
| physics at one point, but Einstein didn't end the
| conversation with LeMaitre then and eventually conceded that
| he was wrong, so it wasn't a 'conclusion', either.
| NoMoreNicksLeft wrote:
| For any given radical-but-rational concept, people must
| instantaneously accept the proposition (instantaneously being
| less than 0.1 seconds after becoming aware of the concept).
| Anything else constitutes science denialism.
| mistermann wrote:
| The Scientismic Method is powerful, and broadly distributed!
| alkyon wrote:
| I wonder if any mass could even colapse beyond Planck length?
| Maybe theory unifying quantum mechanics with Einstein's general
| relativity would have more definite answers.
| dang wrote:
| How about we finesse that by taking out the baity bit from the
| title above.
| shadowgovt wrote:
| TBH, "irrationally" is a value judgment that I can't agree with.
|
| Einstein's approach to physics was to reason out the consequences
| of _observable_ phenomena. He approached understanding of the
| nature of the speed of light by realizing that a universe where
| you could travel as fast as (or faster than) a light ray would
| have consequences that we didn 't see. So when the math tells him
| "gravity causes some regions of space to blow up to become
| inescapable," and we _hadn 't seen black holes yet,_ I think his
| first intuition being that we'd missed a trick that made the math
| fail to match reality was a fine intuition.
|
| Math is only _useful_ to physics to the extent that it actually
| models reality, and not all the extrapolations it makes turn out
| to have practical grounding; sometimes chasing the extrapolation
| reaches a contradiction that demands adjustments to math to fix
| the model. Chasing such adjustments in light of evidence is how
| we reached relativity in the first place.
| baxtr wrote:
| I don't want to open another box, but how exactly do people
| distinguish between rational vs irrational behavior?
|
| You might define it as quick system 1 vs thoughtful system 2
| reaction.
|
| But I'm pretty sure Einstein had thought this through and had
| good, rational reasons at that time to "resist" the idea of black
| holes.
| lucianbr wrote:
| There may be exceptions, but most of the time I find people
| call "irrational" any reasoning they disagree with.
| lukan wrote:
| Rationality is apparently relative.
| circuit10 wrote:
| It's still possible to have biases when thinking something
| through deeply
| baxtr wrote:
| Absolutely. But then what exactly is being rational
| treflop wrote:
| I think pretty much everyone is rational.
|
| However, our access to facts and information is vastly
| different between two different people. That's because we grow
| in different spaces, meet different people, and have vastly
| different experiences.
|
| Then you fall into this trap where you think you are right. You
| ARE right, but only in the context of your experience. Since
| it's rarely possible to ever know if you are universally right,
| you have to keep an open mind, which can be difficult.
| MacsHeadroom wrote:
| An irrational belief is one you did not come to through reason.
|
| Irrational doesn't mean bad or wrong. It just means it did not
| come from a rationale. Many beliefs we have are presuppositions
| which we demand strong rationale for changing, despite not
| needing similar rationale to arrive at the presupposed belief.
|
| Believing the earth is flat because it looks flat is an example
| of an irrational belief practically everyone holds until taught
| otherwise. Some people hold onto the belief even after being
| given good reason to abandon it. We call that irrational
| behavior.
| baxtr wrote:
| I like the flat earth example.
|
| However, it seems to me that your definition is circular.
|
| You define irrational as the opposite of being rational.
|
| I'm pretty sure that flat earthers have their own "rationale"
| why the earth must be flat and we are the irrational ones to
| them.
|
| The circular definition is not good enough.
| MacsHeadroom wrote:
| Having rationale to support your belief is inconsequential
| to whether it is rational or not. The important distinction
| is whether you arrived at the belief through rationale or
| not. Everyone believes the earth is flat by default because
| it appears flat. That's what makes it irrational.
|
| If you later revert to believing in the globe because of
| reason and then convert back for reasons none of that
| matters. The initial belief was always irrational.
| brcmthrowaway wrote:
| What is the function of the blackholes in a rational universe?
| akira2501 wrote:
| Maybe enforcing the second law of thermodynamics? Or they're a
| consequence of the same. It's a region of space where the
| conditions that existed before the big bang have ostensibly
| reestablished themselves, which is why it appears as a 2d
| boundary phenomenon to us.
|
| I am a total crank.
| brcmthrowaway wrote:
| 1/1,000,000 cranks will be right.
| newpavlov wrote:
| Plenty of physicists are still "resistant" to the idea of black
| holes having a real singularity. The recent Kerr paper [0] only
| adds fuel to this resistance with its hilarious statement "Faith,
| not science!" about singularity proponents.
|
| [0]: https://arxiv.org/abs/2312.00841
| lawlessone wrote:
| Infinite density is pretty crazy though. Would it change much
| from the outside perspective if there was something more like
| an ultra compact neutron star at the center?
| newpavlov wrote:
| A very simplified idea is that the denser you get, the slower
| time flows (for an "outside" observer). So while for an
| "inner" observer density rises "fast" to the point of
| singularity, for an "outside" observer time just freezes
| inside the forming black hole. Finally, if there is a way for
| black holes to "evaporate" (e.g. Hawking radiation), the
| "inner" observer will be able to observe shrinking black
| hole.
| pdonis wrote:
| No, this doesn't work. The "slower time flows" you is an
| optical illusion caused by the curvature of spacetime. It
| is not a way to avoid the formation of a black hole.
| newpavlov wrote:
| Are you talking about the Hawking-Penrose theorems? Have
| you read the Kerr paper?
| pdonis wrote:
| _> Are you talking about the Hawking-Penrose theorems?_
|
| No. Your wrong claim about the slowing of time flow has
| nothing to do with those.
|
| _> Have you read the Kerr paper?_
|
| Yes. It doesn't say anything like what you were saying. I
| have commented on it elsewhere in this discussion.
| effie wrote:
| Can you please give some reference for this claim? Time
| stopping at the event horizon is quite the standard view
| in "science communication" of black holes.
| pdonis wrote:
| _> Would it change much from the outside perspective if there
| was something more like an ultra compact neutron star at the
| center?_
|
| There can't be anything like that at the center; that kind of
| solution doesn't work. At least, not if there is an actual
| event horizon.
|
| The most likely solution, IMO, is that there is no actual
| event horizon, and the horizons we are seeing in our
| observations are only apparent horizons. There are
| theoretical possibilities such as the "Bardeen black hole"
| (which is misnamed since it has no actual event horizon) that
| look like standard classical GR black holes from the outside
| for a time on the order of the Hawking evaporation time,
| which means we would not be able to observe the difference
| now or for the foreseeable future. But what is deep inside
| those solutions is not any kind of ordinary compact object
| like a neutron star.
| binary132 wrote:
| Pardon my ignorance, but why not? This is what I've long
| assumed is the true nature of black holes -- not some kind
| of divide-by-zero error, but merely a very very heavy
| object.
| pdonis wrote:
| _> why not?_
|
| Because no ordinary object, i.e., object made of ordinary
| matter obeying an ordinary matter equation of state, can
| be that compact. It's not possible.
|
| Solutions like the "Bardeen black hole" adopt a different
| equation of state in their deep interior, something more
| like dark energy, which is not any kind of "ordinary
| object". That is the only way to have an object that
| compact without an event horizon. The missing piece in
| such solutions is how that kind of equation of state
| could arise as a result of something like stellar
| collapse: that is where some kind of new physics,
| possibly some form of quantum gravity, might be needed.
| pdonis wrote:
| _> Plenty of physicists are still "resistant" to the idea of
| black holes having a real singularity._
|
| That's because most physicists expect that new physics,
| probably some form of quantum gravity, will come into play
| before the singularity is reached, so that there won't actually
| be one. Which is a perfectly reasonable expectation.
|
| _> The recent Kerr paper [0] only adds fuel to this resistance
| with its hilarious statement "Faith, not science!" about
| singularity proponents._
|
| Kerr misrepresents the actual opinion of most physicists in
| that paper. The simplest way to see this is to realize that
| Kerr's statement that if a theory predicts singularities, the
| theory is wrong, is something that virtually all physicists who
| work in GR _agree with_! Practically nobody believes that there
| are actual curvature singularities; they believe that GR is not
| correct in that regime, and some kind of new physics is
| involved, as I noted above. So in the sense Kerr uses the term,
| there are practically _no_ "singularity proponents" at all. He
| is attacking a straw man.
| newpavlov wrote:
| >The simplest way to see this is to realize that Kerr's
| statement that if a theory predicts singularities, the theory
| is wrong, is something that virtually all physicists who work
| in GR agree with!
|
| Maybe it was my misfortune, but the university professor who
| taught me GR thought that singularities are "real", so this
| anecdote (sadly) disproves your absolutist opinion. And there
| are heaps of real papers from real scientists which seriously
| discuss potential consequences of having "real"
| singularities. And if we'll take a look at the pop-sci
| coverage, it's orders of magnitude worse... Just see the
| Veritasium video linked in the other comment.
| pdonis wrote:
| _> the university professor who taught me GR thought that
| singularities are "real"_
|
| Did he teach it from Wald's classic textbook? Wald, Chapter
| 9, explicitly disclaims any belief that singularities are
| real and explicitly says the classical GR prediction of
| singularities indicates a breakdown in the theory in that
| regime. Other classic textbooks like Misner, Thorne, &
| Wheeler say similar things. So do many peer-reviewed papers
| published in the field.
|
| Sadly, I am not surprised, though I am disappointed, that
| many university professors do not know the subject they are
| teaching well enough to be aware of what I have just said.
| But the fact remains that the statements I have described
| are the ones Kerr (who certainly cannot claim ignorance on
| the part of whoever taught him GR as an excuse) should have
| been looking at to gauge the prevailing opinion of actual
| researchers in the field. But he didn't.
|
| _> if we 'll take a look at the pop-sci coverage_
|
| Nobody should be relying on pop science to learn actual
| science. Nor should anyone claim that pop science coverage
| is an accurate gauge of the opinions of actual researchers
| in the field.
| floxy wrote:
| >He is attacking a straw man.
|
| But the Nobel prize was awarded for the Singularity
| Theorem(?). Maybe Kerr is attacking something in between a
| straw-man and a steel-man? Clay-man?
| pdonis wrote:
| _> the Nobel prize was awarded for the Singularity Theorem_
|
| Sure, because those theorems played a very important role
| in clarifying exactly what classical GR predicts in these
| regimes, and therefore in focusing the efforts of
| physicists in fruitful directions. That remains the case
| even if it turns out that in our actual universe, at least
| some of the assumptions of those theorems are violated so
| that there aren't any actual singularities. One of the key
| contributions of the singularity theorems was in making
| those assumptions clear, so that physicists who did not
| believe singularities were physically realistic knew
| exactly where to look for other possibilities.
| ClumsyPilot wrote:
| Haven't we basically proven that even horizon is real? At
| which point, isn't anything inside sealed off by gravity, the
| fact that time slows down infinitely, the hypothesised
| firewall, etc?
|
| I.e. if a black hole has a singularity or a super heavy
| pokemon, there is no distinguishable difference in our
| universe?
| pdonis wrote:
| _> Haven't we basically proven that even horizon is real?_
|
| No. All we have shown is that there are compact regions in
| our universe that look like event horizons--but could also
| be just apparent horizons. To know that they are actual,
| true event horizons, we would have to know the entire
| future of the universe, since an event horizon is a
| globally defined surface in spacetime and its presence and
| location cannot be known unless you know the entire
| spacetime, i.e., the entire future. If you don't know that
| --and of course we don't--you can't tell an actual event
| horizon from an apparent horizon.
|
| _> isn't anything inside sealed off by gravity, the fact
| that time slows down infinitely, the hypothesised firewall,
| etc?_
|
| None of these are actual features of actual event horizons
| (or apparent horizons, for that matter). The first is a
| missatement--the gravity of the object is not "sealed off"
| and can still be detected outside. The second is an
| illusion caused by an unfortunate choice of coordinates.
| The third is pure speculation, and speculation which does
| not appear to have gained much traction.
|
| _> if a black hole has a singularity or a super heavy
| pokemon, there is no distinguishable difference in our
| universe?_
|
| Most physicists do not believe that either of these (if I
| take "super heavy pokemon" to mean "some kind of ordinary
| compact object like a neutron star") is what actually
| happens.
| umvi wrote:
| This article seems like a rehash of the recent Veritasium video:
| https://www.youtube.com/watch?v=6akmv1bsz1M
|
| For example, compare the picture of Karl Schwarzschild in the
| article to 7:54 in the Veritasium video. Just a coincidence?
| empath75 wrote:
| https://today-in-wwi.tumblr.com/post/144234528063/karl-schwa...
|
| Looks like the BBC used this photo as reference for the
| drawing.
| rosmax_1337 wrote:
| To this day I believe black holes remain a mostly theoretical
| phenomena. Which also happens to deal with infinity-mathematics
| in the singularity, something we don't see in reality otherwise.
|
| Yes, observations have been made to their advantage, through LIGO
| and more recently the image from 2022 of a black hole made by the
| Event Horizon Telescope. But I would stress that the ""image"" is
| much more complex than simply a photo from really good
| ""telescope"", it's a image made of combined data from radio
| telescopes all around the world. There is enough weird hoops that
| they need jump through that the observation can reasonably be
| doubted in my opinion, which isn't to say that what they've
| attempted is awesome and inspiring.
|
| Please correct me if you have other information.
| empath75 wrote:
| They've been detected with gravity waves, radio telescopes and
| optical telescopes and explain a wide variety of phenomena in
| the center of galaxies.
|
| What evidence would you require to confirm that they exist?
| pdonis wrote:
| The objects we have detected look like classical GR black
| holes, yes.
|
| The problem is that, theoretically, there are other possible
| objects that look like classical GR black holes from the
| outside for a very, very long time, but still aren't
| classical GR black holes. We have no direct way of telling
| from observation whether the objects we have detected really
| are classical GR black holes, or whether they are one of the
| other possibilities.
| pdonis wrote:
| _> black holes remain a mostly theoretical phenomena_
|
| The fact that there are compact objects in our universe that,
| from the outside, look like the black holes that GR predicts,
| is not "theoretical", it's observation.
|
| The theoretical question is whether these objects really are
| classical GR black holes "all the way down", so to speak, or
| whether there is some new physics that comes into play deep
| inside them (which many physicists think will involve some form
| of quantum gravity) that changes things. Even if the latter is
| the case, the objects might still look like classical GR black
| holes from the outside for a very, very long time, on the order
| of the Hawking evaporation time (10^67 years for a one solar
| mass hole, and the time goes up as the cube of the mass). So
| for all practical purposes, treating them as classical GR black
| holes works fine now and for the foreseeable future.
| sega_sai wrote:
| When there is no experimental evidence for black holes, it makes
| perfect sense to be resistant/skeptical to new type of objects
| with solutions involving infinities (singularity). Whether that's
| being irrational or not is up to debate. I'd say that's a good
| prior when there is no data (as there wasn't at the beginning of
| 20th century).
| davidcuddeback wrote:
| Case in point: the same equations predict white holes, which
| today are widely believed to not exist.
| chgs wrote:
| I've never seen one before -- no one has -- but I'm guessing
| it's a white hole.
| jokoon wrote:
| I don't know a lot of advanced physics or quantum mechanics,
| but black holes also confuse me.
|
| I would imagine that black holes show the limit of modern
| physics, there are still things to learn, and models of physics
| will probably be adjusted in the future.
|
| I guess there are physicists who are able to predict how a
| black hole works and appears, and how it can be explained, but
| I haven't read about it.
| WhitneyLand wrote:
| Well yes, but they also knew stars collapsed, and that
| something had to happen in that case. Maybe at first they
| thought fine, everything becomes a white dwarf or a neutron
| star.
|
| But then after Oppenheimer did the math in 1930 and showed that
| collapse into a black hole was within the theory of relativity
| would you still taken the same position?
| VagabundoP wrote:
| This stuff was cosmic horror to all these folk. It caused
| existential crisis when you try imagine what is happening in and
| around a black hole. I'm not surprised they did everything they
| could to deny and disprove it.
|
| Most would have had religious convictions that were really
| challenged by the physical reality of the universe.
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