[HN Gopher] I stopped working on black hole information loss
___________________________________________________________________
I stopped working on black hole information loss
Author : nsoonhui
Score : 322 points
Date : 2022-04-23 13:28 UTC (9 hours ago)
(HTM) web link (backreaction.blogspot.com)
(TXT) w3m dump (backreaction.blogspot.com)
| paulpauper wrote:
| Just because it's not testable does not mean it's not worthwhile.
| General relativity would still exist even if it could not be
| tested, fortunately , it is easy to empirically verify. But if
| the math is sound and meets certain assumptions, then it may be
| the correct theory. Having many mathematically sound candidates
| for a correct theory is better than nothing. That' why it's
| called theoretical physics. She seems to be ignoring that part.
| By her logic, theoretical physics is a waste of time.
| The_rationalist wrote:
| phn wrote:
| If someone could challenge my layman understanding:
|
| Isn't the information still there, inside the black hole, but
| just not retrievable from the outside?
| seanw444 wrote:
| That's what I thought too. If they expand as they swallow
| matter, doesn't that easily explain that it's still in there?
| jeremyjh wrote:
| If you simply read the SFP you'd know the answer to this. It
| isn't there forever, because the black hole is not there
| forever.
| Sukera wrote:
| Disclaimer: I'm not even a physicist.
|
| As I understand it, the trouble is with "what happens to the
| information inside the black hole?", not with whether it's
| there at all or not (which isn't disputed - we see stuff fall
| in, so it's gotta go _somewhere_ and it isn't in our
| observable part anymore). In addition, because of the nature
| of a black hole, how would an experiment trying to test any
| theory about what happens in a black hole even work? As far
| as I'm aware, we don't know of any mechanism where stuff
| inside the black hole affects stuff outside the black hole
| (hawking radiation doesn't, as far as I'm aware, explain
| _how_ the spontaneous quantum fluctuations come to be -
| they're just theorized to happen to satisfy the equivalence
| principle near the event horizon), but that's exactly what
| we'd need to confirm or deny anything about whatever happens
| past the event horizon.
|
| On top of this, just the existence of hawking radiation means
| black holes vanish over time - but without us being able to
| say that e.g. a book with mass 1kg or a bag of sugar with
| mass 1kg was once thrown in. We can't distinguish the two
| cases - the information (as far as we know today) is lost.
| wanda wrote:
| That's correct for general relativity alone, but GR isn't
| enough on its own.
|
| Hawking showed that the information is lost in the process of
| black hole evaporation as the black hole decays into anonymous
| radiation, and so once a black hole is gone so too is any trace
| of the matter it absorbed in its lifetime.
|
| It's this bit that isn't okay in quantum mechanics, and that's
| problematic because quantum mechanics certainly seems to be
| bang on the money for a great deal of other phenomena.
|
| One would have a hard time saying that QM was wrong. That's not
| to say that it is a complete theory, but QM has made many,
| highly accurate predictions that have served to edify the
| framework.
|
| I don't know how certain it is that black holes evaporate. It
| may seem tempting to think that perhaps it is this notion of
| evaporation that could be overturned, but then you have black
| holes which simply exist forever, which would be rather
| problematic as well.
| raattgift wrote:
| FWIW, I've been enjoying your comments in this discussion.
|
| > It may seem tempting to think that perhaps it is this
| notion of evaporation that could be overturned, but then you
| have black holes which simply exist forever, which would be
| rather problematic as well.
|
| Why is a bound state of matter in a black hole lasting until
| the infinite future more problematic than a bound state of
| matter in a proton lasting until the infinite future? Is a
| theory with non-decaying protons problematic compared to a
| theory with proton decay?
|
| Essentially, gravitational collapse and horizon-formation is
| not the information loss problem -- the information still
| exists inside a growing black hole, we're just disconnected
| from it by virtue of being on the other side of the horizon.
| Compare with the information from the very early universe
| which has exited the observable universe thanks to the metric
| expansion. Or the information in the universe outside the
| Rindler horizon of an accelerated observer.
|
| Expand the universe forever, and for every observer more and
| more information goes to the other sides of cosmological and
| black hole horizons.
|
| Time reversal leads to interesting thoughts: galaxies with
| stones (and maybe people, chairs, and xylophones) coming into
| view from beyond the horizon all seems fine if we time-
| reverse our universe. Likewise for a black hole that had such
| things fall into it in our ordinary arrow-of-time direction,
| we should expect that things like stones could be spat out
| under time-reversal. The information loss problem arises when
| a black hole completely evaporates to thermal noise: how does
| the time-reversed black hole, formed from inrushing thermal
| noise, know that it should eventually spit out xylophones
| rather than violins?
|
| We need that knowledge in our time-reversed black hole. Does
| it rush in along with the thermal noise?
|
| The time reversal picture starts with big primordial black
| holes that fission into smaller ones, with those spitting out
| dust, gas, dead planets, space probes, stars and so on.
| Thanks to the time-reversed metric expansion, these spit-out
| observers also see a bunch of previously unseen black holes
| rush into view and spit out things like cats and space
| probes.
|
| This isn't a problem, the recipe for all that can be deemed
| to be inside the primordial (in the time-reversed sense)
| black holes: it's part of the initial values surface, with
| the relevant values initially inside the black hole horizons.
|
| What if we time-reverse from an expanded universe where all
| black holes have evaporated into thermal noise? Do we have to
| rely on fluctuations (Boltzmann brains!)? Or on "false noise"
| as the initial values surface, with dynamical laws that
| create detailed structure as we do an adiabatic compression
| of the seemingly structureless cold gas? Or both? We need to
| get lots of widely-separated black holes at early times when
| our collapsing universe is big and sparse, rather than at
| late times when everything is much closer and hotter. We also
| need it to be correct when we time-reverse the time-reversed
| picture.
|
| I'm not sure that the problem is qualitatively very different
| when one thinks classically or quantum mechanically, although
| the latter sharpens the vocabulary somewhat ("unitarity!")
| and introduces some fuzzy questions about entanglement energy
| (Almheiri, Maroff, Polchinksi, Sully 2012 and subsequent
| fiery discussion).
|
| The problem is that the singularity blocks time-reversal
| classically, and in the absence of time-reversibility one
| cannot have unitary evolution (T-symmetry is necessary but
| insufficient for unitarity, so some (semi-)classical solution
| that abolishes the singularity might turn out not to resolve
| the whole information loss problem).
|
| However, a cosmos with black holes that never evaporate seems
| to abolish most of the "final values surface" problem: we
| don't know what the quantum numbers are exactly, but at least
| we know _where_ they are: they 're mostly localized inside
| black holes.
|
| Finally, in the time-reversed picture we blow apart our poor
| primordial protons during reverse-baryogenesis anyway, but at
| least stable protons in our usual arrow-of-time direction
| means we know where almost all the funky GUT epoch numbers
| are in our very very far future (ignoring black hole
| evaporation).
| hsn915 wrote:
| Covered in the video/article.
|
| I'll post the relevant paragraphs, all quoted directly
| (verbatim) from the blog post:
|
| Physicists knew about this puzzle since the 1960s or so, but
| initially they didn't take it seriously. At this time, they
| just said, well, it's only when we look at the black hole from
| the outside that we don't know how reverse this process. Maybe
| the missing information is inside. And we don't really know
| what's inside a black hole because Einstein's theory breaks
| down there. So maybe not a problem after all.
|
| But then along came Stephen Hawking. Hawking showed in the
| early 1970s that actually black holes don't just sit there
| forever. They emit radiation, which is now called Hawking
| radiation. This radiation is thermal which means it's random
| except for its temperature, and the temperature is inversely
| proportional to the mass of the black hole.
|
| This means two things. First, there's no new information which
| comes out in the Hawking radiation. And second, as the black
| hole radiates, its mass shrinks because E=mc^2 and energy is
| conserved, and that means the black hole temperature increases
| as it evaporates. As a consequence, the evaporation of a black
| hole speeds up. Eventually the black hole is gone. All you have
| left is this thermal radiation which contains no information.
| thwd wrote:
| Gravity is infinite at the singularity (the middle of the black
| hole). Everything gravitates towards that point. Our best
| understanding is that no information can exist here.
|
| Black holes "evaporate" over time -- by emitting Hawking
| radiation. This is probably where the information goes, in my
| layman understanding.
| tsimionescu wrote:
| > Black holes "evaporate" over time -- by emitting Hawking
| radiation. This is probably where the information goes, in my
| layman understanding.
|
| No, the Hawking radiation and evaporation is exactly what
| causes the problem. If black holes were forever expanding, we
| could simply say "they have a structure inside that we can't
| detect, but that structure preserves the information; but,
| since it's past the event horizon, it will be, even in
| principle, forever beyond reach of our understanding and
| experiment".
|
| However, if black holes eventually disappear, it means you
| have something like book => unknowable inside of the black
| hole event horizon => something observable outside. The
| problem now becomes that, from Hawking's discovery, the
| "something observable outside" is random thermal radiation,
| which can't contain information by definition. Hence, not
| just something unknowable, but a paradox (an inconsistency in
| the formal model).
| trhway wrote:
| information paradox of the modern science - reduce everything to
| a model of a spherical horse in a vacuum, and after that run
| around shouting that it isn't possible for the horse to have
| distinguishing features, like the horse's sex, color, breed, etc.
| klik99 wrote:
| Sounds like they're a trisolarian agent
| geysersam wrote:
| The opposite! Debating where effort should be spent is crucial.
| Trisolarians would love to see more research into unknowable
| multiverse stuff.
| ffhhj wrote:
| We might be able to create our own BH to test theories:
|
| > The LHC will not generate black holes in the cosmological
| sense. However, some theories suggest that the formation of tiny
| 'quantum' black holes may be possible.
| clord wrote:
| Doesn't the black hole just delay the information, not destroy
| it? Things that "fall in" from our perspective just fade down
| into a static low frequency frozen image on the horizon, and the
| remaining trip to the horizon as seen from the outside takes
| infinite time.
|
| The falling perspective likewise loses timely access to
| information about the entire universe as the singularity fills
| their view.
|
| I don't see a paradox. Just the strange behavior of time at the
| limit.
| wanda wrote:
| That's not the paradoxical part. Matter goes in, sure. But
| before it goes in, it is something, it has a form and a
| composition, it is in a state and it contains information of
| its prior states as well.
|
| The part that is problematic is that matter that enters the
| black hole is only returned to the universe as anonymous
| radiation.
|
| The universe is stateful, and while not all processes in the
| universe are reversible, matter and energy do encode the states
| that led to their present state and thus the prior states can
| be inferred (by a hypothetical, powerful enough computer, for
| example).
|
| The problem with black holes is that the Hawking radiation from
| a black hole does not encode any information about its prior
| state.
| lamontcg wrote:
| But that just suggests that at some high enough energy that
| QM becomes nonlinear and singular and nonreversible and
| information is destroyed.
| lisper wrote:
| I think you missed the GP's point, which is that matter is
| never "returned to the universe" because from any frame of
| reference outside the horizon, the matter takes infinite time
| to transit the horizon, so it never actually appears to enter
| the hole.
| dllthomas wrote:
| How does that remain true after the black hole has
| evaporated and there is no longer a horizon?
| lisper wrote:
| Disclaimer: we are at the hairy edge of my knowledge
| here, so what I am about to tell you could very well be
| wrong.
|
| Hawking radiation has never actually been observed. It is
| just something that pops out of the math if, as Sabine
| rightfully emphasizes in her video, you make certain
| assumptions. And one of those assumptions is that you
| have a fully-fledged black hole, i.e. an object that
| actually contains mass beyond the event horizon. We are
| used to thinking of this assumption as having actually
| been confirmed by observation, but it is not actually
| true. No one has ever actually observed a black hole,
| notwithstanding that we've ostensibly taken a picture of
| one. That image was of the radiation emitted by an
| accretion disk, not the black hole itself. Black holes
| themselves are, obviously, impossible to image.
|
| So we don't actually know whether black holes actually
| exist or not. The only thing we've directly observed is
| their gravitational effects, and the gravitational
| effects of an actual black hole are indistinguishable
| from having all of the mass of the hole actually resident
| just outside the event horizon. What actually happens at
| the horizon is beyond the reach of our current theories
| because there both gravity and quantum effects are
| significant, and we do not yet have a consistent theory
| of quantum gravity. Everything we think we know about
| black holes is actually the result of taking GR and QM
| and framming them together in some ad hoc way by adding
| simplifying assumptions which may or may not actually be
| true.
|
| This is the point Sabine was trying to make: the black
| hole information loss paradox is not a problem with
| physics, it's a problem with our current theories. We
| simply don't know how the universe actually behaves in
| the presence of extreme concentrations of mass/energy.
| The only thing that the BHILP actually tells us is that
| either GR or QM -- or both -- are wrong, mere
| approximations to the actual truth in the same way that
| Newtonian mechanics turned out to be an approximation to
| the actual truth (one that happens to work extremely well
| in weak gravitational fields).
|
| But no one has a clue which one is wrong or how despite
| 100 years of effort. And one of the reasons for this is
| that we have no data, and no reasonable prospects for
| obtaining it. So we may just have to make our peace with
| not knowing.
| wumpus wrote:
| > Black holes themselves are, obviously, impossible to
| image.
|
| What we observe is the "shadow" of the black hole. The
| expectation is that the flux from the shadow should be
| consistent with zero. For M87* the observed flux ratio
| with the ring was ~10:1. See Paper 1:
|
| First M87 Event Horizon Telescope Results. I. The Shadow
| of the Supermassive Black Hole
| https://arxiv.org/abs/1906.11238
| vl wrote:
| >Black holes themselves are, obviously, impossible to
| image.
|
| Unless they produce Hawking radiation. Then by definition
| they are possible to image. In the original article she
| mentions that temperature of known black holes is lower
| than CBR, meaning that they are too cold to be seen
| agains background of cosmic background radiation.
|
| I personally think that they produce no radiation and do
| not evaporate, but this is just unscientific
| philosophical opinion.
| lisper wrote:
| > Unless they produce Hawking radiation.
|
| Fair point (modulo the practical difficulties of
| measuring Hawking radiation).
| platz wrote:
| Wall of text, didn't answer the question.
| lisper wrote:
| The question assumes that black holes evaporate, and we
| don't actually know that they do.
|
| Is that better?
| platz wrote:
| That is a more transparent answer and direct answer, yes.
| Maybe if you had lead with that sentence, I wouldn't have
| been inclined to respond. But it also fails to address
| what I point out below. (as an aside, this answer is also
| not one that I find satisfactory on the actual topic.)
|
| Dllthomas correctly pointed out that given the two
| premises that (from the frame of the observer) (1)
| [matter takes infinite time to transit the horizon] and
| (2) [due to hawking radiation, black holes have a finite
| time span], then (2) resolves (1) when the black hole
| disappears.
|
| To recap, Instead of acknowledging that (2) resolves (1)
| you proceed to question the existence of hawking
| radiation and black hole evaporation, which compared to
| consensus is a radical view and is not warranted. Also
| the pivot was done in a way that seems to complicate and
| obfuscate rather than address the point directly (this is
| a common debate tactic; however I'm not sure if you were
| conscious of the behavior or if it was more
| subconscious/rationalization (more likely); you may not
| have even been aware you were doing it).
|
| It seems like you chose to reject consensus instead of
| simply accepting that (2) resolves (1), maybe because you
| seem to have a fixation on not ever conceding a point in
| a conversation. Sometimes it's ok just so say, "yeah,
| that's a good point".
|
| (btw if you're rejecting hawking radiation why say
| anything about black hole theory at all this point
| because it could all be wrong, no reason to speculate
| about it)
| lisper wrote:
| > you seem to have a fixation on not ever conceding a
| point
|
| That is quite the accusation coming from someone whose
| entry into the conversation was "Wall of text, didn't
| answer the question." But let's see...
|
| > Dllthomas correctly pointed out...
|
| dllthomas did not "point out" anything, correctly or
| otherwise. All he did was ask the following question:
|
| "How does that remain true after the black hole has
| evaporated and there is no longer a horizon?"
|
| This question _assumes_ that black holes evaporate. That
| assumption may be incorrect. We do not know whether or
| not black holes actually evaporate. In fact, we do not
| even know whether or not black holes actually form at
| all. And therefore:
|
| > (2) resolves (1) when the black hole disappears
|
| That might be true if (2) were true. Even that is
| arguable, but it is neither here nor there because we do
| not know whether or not (2) is true
|
| > compared to consensus is a radical view
|
| Yes, of course. The consensus view leads to a paradox,
| and so we know that the consensus view cannot possibly be
| correct. We also know that decades of effort have not
| resolved this paradox, and so it is extremely unlikely
| that there is a simple straightforward solution that has
| simply been overlooked. So the correct solution will
| almost certainly be a radical departure from the current
| consensus.
| polishdude20 wrote:
| It's fascinating to think that our theories on everything
| around us are based on everything near us enough to be
| measurable and experimented on. Black holes are so far
| away and so outside of our normal observations of mass
| and energy that we can't observe them well enough to do
| experiments.
|
| It's like we've come up with two theories of how the
| universe works but and the universe is like "you guys are
| like 90% there but here's a case where these don't
| work.". It's fascinating to think that there's gotta be
| some one theory that can account for everything in the
| universe both big and small from black holes to quantum
| stuff. It's like we've dug ourselves in two very deep
| holes over the years and maybe we need someone to come
| along with a new hole that encompasses both things that
| see the whole picture. Anyways now I'm just speculating.
| lisper wrote:
| > there's gotta be some one theory that can account for
| everything
|
| Actually, there doesn't. The universe is under no
| obligation to operate according to laws. That the
| behavior of the universe is so lawful is quite
| remarkable. It didn't have to be this way. Our universe
| could be a simulation, and that simulation could have
| been created by some capricious being who makes all kinds
| of random shit happen just to fuck with us. That does not
| appear to be the case, but there is no reason that it
| could not have been.
|
| Likewise, there is no reason why our brains should have
| the capacity to be able to figure this out. It may be
| that the Kolmogorov complexity of the universe is vastly
| larger than what the human brain is capable of dealing
| with. Again, this does not appear to be the case. In
| fact, it appears to be the exact opposite. We can explain
| 100% of the phenomena within our solar system, and even
| within most of our galaxy, with theories whose KC is
| shockingly low, small enough to be grasped by a single
| human brain. But it didn't have to be that way. And maybe
| it isn't that way. Maybe we have actually reached the
| limit of what the human brain is capable of (in terms of
| figuring out physics). I don't think so, but you can't
| rule out the possibility on the basis of the evidence we
| have.
| polishdude20 wrote:
| I'm just saying there's gotta be because of what we've
| observed so far. Like you said, we can explain 100% of
| the phenomena in our solar system. It leads to believe
| that we can do that in the future for things outside of
| it.
|
| Also, just because a theory is discontinuous at its
| boundaries doesn't mean we can't have a theory that is on
| the other edge of that boundary. The unifying theory is
| supposedly supposed to link both general relativity and
| quantum mechanics.
|
| Obviously this is just my opinion but I think any system
| that is sufficiently observable, with enough time can be
| figured out completely. I don't think it's a matter of if
| our brains can understand it but if we can have the
| ability to run experiments on it and enough time.
| daxfohl wrote:
| I think that's the point. From an outside perspective the
| black hole will evaporate before the thing falls in. Thus
| a thing can never fall in. From its perspective the hole
| will emit more and more intense radiation and finally
| evaporate just before it hits the horizon.
|
| If true, I think you can go even further and say no black
| hole can completely form; the collapsing matter just gets
| exponentially closer to being fully black until the
| effect of the Hawking radiation outweighs the
| gravitation, but it all evaporates before going fully
| black. No?
|
| (This latter part assumes there's some Hawking radiation
| or equivalent from pre-black holes as well. And I'm not
| sure whether that would be unitary or not, so it may not
| resolve the information paradox anyway).
|
| (Edit: I think the pre-Hawking radiation would be
| unitary, since the only reason Hawking radiation is not
| unitary is because BHs don't have information, but pre-
| black holes are not black holes. So doesn't that solve
| the info paradox? Without resorting to holographs and
| whatnot? Where's the error?)
| Raidion wrote:
| Totally uninformed here:
|
| Have we proved the Hawking radiation is without information
| (or enough of it), or is it just 'encrypted' at a level we
| can't distinguish from noise?
| jfengel wrote:
| The theorems that derive it's existence don't use the
| underlying state. They come from the margins of a black
| hole, which completely hides what's in it. That's the No
| Hair Theorem.
|
| If information leaks out they'll have to figure out why the
| No Hair Theorem is wrong.
| theptip wrote:
| A lot of complexity is hidden behind the term
| "information". You should be careful not to just use your
| existing intuition/definition for this word, it's extremely
| specific Quantum Mechanics jargon here.
|
| This is talking about quantum states and how they describe
| the world. Each state corresponds to physical (quantum)
| reality, conforming to the laws of physics. So it's not
| like you can just twiddle bits to make new representations.
|
| I think this is an area where appealing to the lay reader's
| intuition is counterproductive. If you haven't solved the
| Schrodinger equation before then you definitely shouldn't
| be trying to intuit things about quantum systems; they are
| just weird and kind of irreducibly complex from the
| mathematical representation.
|
| Let me attempt to go against my advice above and give you
| some intuition for why encryption doesn't parse here. It
| would be like you have a program with some static types,
| some classes, and then say "what if we just encrypt the
| memory location for this object on the heap and run the
| program". The program is the thing that is running (laws of
| physics), the variables on the stack/heap are the state for
| the current execution, and it has no concept of decryption,
| so it would just produce garbage and crash. In the same
| way, the quantum physics description of a system has
| superposed states that are all valid configurations of the
| physical system, and no notion of "encryption". So there is
| nowhere in the model of physical reality (and therefore
| unless we are missing some new Physics, nowhere in the
| reality that is modeled) for this information to "hide".
|
| Or taking a different tack, "thermal entropy" means it's
| just a bunch of gas buzzing around randomly at the same
| temperature - there is no physical place for structure to
| be "encrypted". Where is the "key" in your model of the
| world? It's just a cloud of gas. What physical process
| performed the encryption? That would require a complex
| structure, yet we are talking about a cloud of particles
| emitted when one half of a particle-antiparticle pair is
| captured by the black hole's event horizon. There is no
| place in a workable physical model of the world for an
| entity that performs encryption on the quantum states
| (whatever that might mean).
|
| All this just points to why you can't encrypt states in
| this way, not why the black hole information paradox is a
| problem. For that you really do need the maths; eg see http
| s://www.cs.umd.edu/class/fall2018/cmsc657/projects/group...
| for the Physics here; while that requires graduate-level
| understanding of QM, hopefully the intro will be useful.
| Ar-Curunir wrote:
| > the encryption ... would require a complex structure
|
| Not a quantum information theorist, but am a scientist.
| We actually do have (conjectured) low-complexity one way
| functions, so this by itself is not necessarily true. I
| do agree that it's a fairly unlikely to be the case that
| natural processes execute this algorithm, though.
| theptip wrote:
| I think the GP is thinking of two-way encryption under a
| symmetric key here, else it's hard to see how the
| information isn't still "lost".
| prewett wrote:
| > If you haven't solved the Schrodinger equation before
|
| Heh heh, define "solved"... If I remember my QM class
| correctly, we "solved" the Schrodinger equation for the
| hydrogen atom; the book achieved this by observing "...
| which gives us <equation>, and, hey! look at this! it
| turns out that FamousLastName polynomials--which you've
| never heard of--turn out to solve this equation, here's
| their definition, and... problem solved!" (If I remember
| correctly they were Legendre Polynomials, but maybe that
| was some other equation. And to be fair to the book, it
| was a pretty good book.) After having "solved" the
| equation for one isolated, most-basic atom, they went on
| to say, "basically we have no idea if there is an
| analytic solution for anything more complex".
|
| If manipulating bra and ket vectors symbolically around
| an equals sign counts, we did a lot of that, although it
| did not develop in me the least intuition about QM. But
| then, I never really understood what those bra and kets
| were doing, and my grades steadily dropped (fortunately
| for my GPA there were only three courses). So it's
| possible I might have developed some intuition had I
| understood what was going on.
| lupire wrote:
| Obviously no idea if this is true, but, an object falling
| into a black hole maybe could emit some radiation
| containing the key before the majority of the mass
| "encrypted" into the black hole.
| GTP wrote:
| I'm also totally uninformed, but my gut feeling is that
| physical systems don't encrypt information, at least not in
| the way we assume when talking about encryption. Also if
| you go down that route you risk having something that can't
| be proven: how do you prove that black holes are _not_
| using a one time pad to encrypt information, with each
| black hole using a different and random key?
| [deleted]
| mannykannot wrote:
| This seems to address it (from the article):
|
| "[Hawking] radiation is thermal which means it's random
| except for its temperature, and the temperature is
| inversely proportional to the mass of the black hole. This
| means two things. First, there's no new information which
| comes out in the Hawking radiation..."
|
| Its mass is one of the few things we know from the outside.
| phendrenad2 wrote:
| How do we know it's thermal? How do we know there aren't
| small fluctuations that are too small for us to detect
| millions of miles away?
| mannykannot wrote:
| AFAIK Hawking radiation has never been detected. It is
| hypothesized on the basis of current theories of quantum
| mechanics and gravity, and those assumptions imply a
| thermal distribution of energy. So, we have a reason to
| think that Hawking radiation occurs and has this
| property, while no-one so far has proposed a mechanism
| that would encode data on it.
| tsimionescu wrote:
| It's important to understand that Hawking radiation is
| not something we've observed and have noticed seems
| random.
|
| Instead, Hawking radiation is a prediction of a
| mathematical model. In that model, Hakwing radiation is
| purely random.
|
| If I remember correctly, Hawking radiation is postulated
| to arise because of fluctuations in the vacuum giving
| rise to virtual particle pairs. Normally, these would
| annihiliate back almost instantly. But, when such an
| event happens near the event horizon, one of them may
| fall into the black hole, leaving the other one to
| "escape", and appear as if the event horizon is emitting
| radiation. Since this radiation is caused by random
| fluctuations in the void outside the event horizon, it
| can't be correlated with anything past the even horizon,
| so it can't carry information about that.
| andrewflnr wrote:
| Thermal radiation from a classical object looks "random"
| but still obeys (and in fact inspired) quantum theory.
| The information about the past of the object is there,
| it's just unfeasible to recover. I suspect Hawking
| radiation is the same way.
| lupire wrote:
| Why do you suspect that? Do you deny that quantum
| mechanics is a valid model of the universe?
|
| Or do you believe quantum mechanics is equivalent to
| relativistic mechanins?
|
| Either would unwrite a century of physics.
| GTP wrote:
| Probably for OP this isn't enough: if the radiation was
| carrying encrypted information then it would look random
| without knowing the "key", whatever a "key" could be in
| the context of a physical system. But I think that
| talking about encryption here without a solid preparation
| in the filed of physics it is just trying to apply
| something we know to try to solve some problem we have no
| idea how to approach.
| grogers wrote:
| I mean, hawking radiation itself is unproven - we can't
| experimentally verify it because the temperature of the
| radiation from stellar mass black holes would be too small.
| For small black holes, nobody has seen one 'pop'. In theory
| it's testable but probably not in our lifetimes.
| SnowHill9902 wrote:
| What is problematic about that? In what way does it violate
| the second law of thermodynamics? If anything, it seems like
| a great example of the natural tendency towards disorder.
| Also, it's not possible to infer macroscopic prior states
| even with an infinitely powerful computer. When you mix water
| at different temperatures, entropy is irreversibly increased.
| It's not possible to tell the initial temperatures just from
| the final state.
| wanda wrote:
| > In what way does it violate the second law of
| thermodynamics?
|
| If you read my comment, you will find no mention of the
| second law of thermodynamics or any violation of said law.
|
| In fact, black holes need to evaporate in this way in order
| to comply with said law of thermodynamics.
|
| > When you mix water at different temperatures, entropy is
| irreversibly increased. It's not possible to tell the
| initial temperatures just from the final state.
|
| It is still water, however. You may not be able to say what
| temperatures _W(a)_ and _W(b)_ were from _W(c)_ , but you
| could at least say that _W(c)_ may actually be _W(ab)_ i.e.
| may be the mixture of two bodies of water _W(a)_ and
| _W(b)_.
|
| Bring the same water to a black hole and you have: _W(a)_
| went into a black hole and _x_ came out, where _x_ is some
| random heat.
|
| If you detect the heat _x_ , what could you say about
| anything that may have been before?
|
| If _W(a)_ , _W(b)_ , _Chair(a)_ , _Xylophone(g)_ ,
| _Stone(f)_ , _Person(z)_ or anything went into the black
| hole, only heat _x_ comes out in the end.
| SnowHill9902 wrote:
| Perhaps I'm missing some advanced theories or
| contradictions, but it seems to me quite intuitive or at
| least reasonable that there exists some very efficient
| generators of entropy, i.e. black holes. Even if not
| having fallen into a black hole, such water would have
| decayed to heat and fundamental particles eventually.
|
| Why is it contradicting that it happens much faster in
| some places in the universe? It may be surprising but
| what does it contradict? I'm asking sincerely.
|
| Regarding the water thought, if you recite a poem inside
| a chamber, it turns into heat. If you are outside and can
| only measure that the room slightly increases its
| temperature you also can't recover the poem.
| jfengel wrote:
| It's a subtle point. Several key theorems of thermodynamics
| rely on the ability to count unique states. If you could
| evolve the exact same state in two different ways, the
| proofs would fail.
|
| That's how thermodynamics derives indistinguishable macro
| states from distinguishable micro states. Throw that off
| and thermodynamics stops working.
|
| Since it has worked well so far they're reluctant to throw
| it out. Something has to go, and since they already know
| there's something funny going on where black holes meet
| quantum mechanics, that's the lowest hanging fruit.
| SnowHill9902 wrote:
| So you are saying that if I solve the Schrodinger's
| equation for all the particles that make up her I could
| know where my wife wants to go out for dinner?
| andi999 wrote:
| What is the difference of this paradox to a particle entering
| a gas container, thermalizing, and the ejecting the particle
| (evaporate the gas). Thermal states is described by
| macroobservables only.
| amelius wrote:
| Hmm I thought the laws of physics were time-reversible, but
| then I found this: https://www.wolframscience.com/nks/notes-9-3
| --time-reversal-...
| rssoconnor wrote:
| Same. https://www.youtube.com/watch?v=L2idut9tkeQ is the
| relevant episode from Space Time.
| mannykannot wrote:
| I have wondered that, though without knowing enough to even
| figure out if it is a reasonable question. One follow-on
| thought I had was this: what about the matter that becomes the
| black hole when it forms? When a star collapses into a black
| hole, where does the event horizon first appear?
| lupire wrote:
| What do you mean "where"? It appears at the region one
| Schwarzchild radius away from the center.
| mannykannot wrote:
| Sure, but the Schwarzchild radius is a function of the mass
| within it. I'm thinking by analogy to a galaxy or globular
| cluster, which has enough mass to be a black hole, if it
| were dense enough, but it will not become one unless and
| until some dissipative process has caused it to collapse
| towards its center. When this happens, I am supposing that
| the black hole will first form in the center (where the
| gravity well is deepest), with a large part of the cluster
| mass initially outside of it, and grow as the friction
| continues to feed mass into it. If this is, in fact, a
| reasonable model, would something similar happen in a
| collapsing star? (Only much faster.)
| Andrew_nenakhov wrote:
| Why is information loss such a big deal? Information gets lost
| all the time. Hit the wrong button, and the all-important file
| vault is gone, with all the backups, forever, information in them
| is lost. You might lose a job, but the universe doesn't break
| because of that!
| tsimionescu wrote:
| Not sure if you are joking, but the article covers this.
|
| In principle, according to QM, information is never lost (until
| you make a measurement, but that's a different can of worms).
| In principle, in QM it is impossible to delete information. The
| article explains: if you burn a book, but gather detailed
| information about the fire and the smoke, you can reconstruct
| exactly what every letter on every page looked like, and every
| ink blot you spilled on it 10 years ago.
| xaedes wrote:
| Burn it to ash, collect info about the ash and reconstruct -
| no problem. But if you burn it in a way, that the only
| remains are "random thermal radiation" all the information is
| lost and we have a serious paradox to resolve...
| tsimionescu wrote:
| > But if you burn it in a way, that the only remains are
| "random thermal radiation" all the information is lost and
| we have a serious paradox to resolve...
|
| To quote the famous Spartan answer, If.
|
| That is, QM predicts this is impossible. Even if you threw
| the book into the Sun, you would (I must emphasize again
| _in principle_ ) be able to measure the radiation given off
| by the sun and at some point identify the words of the
| book.
| kgwgk wrote:
| > according to QM, information is never lost (until you
| make a measurement
|
| > you would (I must emphasize again in principle) be able
| to measure the radiation given off by the sun and at some
| point identify the words of the book
|
| Does the "information" [1] survive measurements or not?
|
| [1] "Information? Whose information? Information about
| what?"
| tsimionescu wrote:
| > Does the "information" [1] survive measurements or not?
|
| My understanding is that it doesn't, but I believe that
| may depend on your interpretation of QM. Note also that
| "measurement" is pretty ill-defined.
|
| > "Information? Whose information? Information about
| what?"
|
| About the state of the system (the wavefunction).
| Basically in QM an isolated system cannot reach the same
| final state by more than one route; so, if you know what
| state it's in, you know exactly what route it took, what
| every previous state was.
|
| Maybe the problem is more clear if moving to computation
| from pure physics:
|
| In a classical computer, you can do something like "x = x
| & y; y = y & x". If you run this operation and find that
| x = 0 and y = 0, you can't know what values x and y had
| before, so that information was lost (ignoring other
| physical effects - if QM is right, the information is
| still retained, maybe radiated away by the processor or
| something).
|
| As such, in a quantum computer, this operation simply
| can't be performed. Instead, you have to use an ancillary
| bit, z, and some QC equivalent of the Toffoli gate [0].
| Then you can compute something like {x, y, z} = {x, y, z
| XOR (x AND y)}; {y, x, z} = {y, x, z XOR (y AND x)}; if
| you get the result {0, 0, 1}, you can compute exactly
| what values x, y and z had initially.
|
| The same observations apply to physical interactions.
|
| [0] https://en.wikipedia.org/wiki/Toffoli_gate
| Andrew_nenakhov wrote:
| Or the QM is just wrong about information never being lost.
| tsimionescu wrote:
| Sure, that's a possibility. But, the problem is that this
| feature comes from a very fundamental place in QM's
| mathematics - QM is (almost) a linear theory, and with
| linear equations, information can't be lost. So, to assert
| that QM is wrong about this is to invalidate all of QM's
| equations.
|
| Now, it's important to recognize one thing: QM is not
| _really_ a linear theory, because it also has Born 's rule,
| or the Measurement postulate. That is, while the
| wavefunction evolves according to purely linear equations,
| when you ultimately want to measure the state of the
| system, you get a non-linear update: the wavefunction
| suddenly "collapses" to a single value, and information is
| indeed lost (different wave-functions can collapse to the
| same state after a measurement). However, the measurement
| postulate is itself poorly understood, so its hard to
| introduce it into the discussion without derailing things.
|
| There are even consistent interpretations of QM where this
| doesn't actually happen, such as Many Worlds, where the
| information is actually still preserved across the totality
| of the worlds.
| Aardwolf wrote:
| > They are completely described by only three properties: their
| mass, angular moment, and electric charge
|
| What about linear momentum, if the black hole has some velocity
| through space is that not also a parameter of it?
| delusional wrote:
| I don't think linear velocity is necessary to describe a black
| hole. Basically, a black hole that moves behaves exactly the
| same as one that stands still.
| Aardwolf wrote:
| What's different about angular momentum in that case? Given
| that rotating or not rotating is also similar to moving or
| standing still
| [deleted]
| Koshkin wrote:
| The (important) difference is that a rotating frame of
| reference is not inertial.
| [deleted]
| dark-star wrote:
| Rotating black holes behave quite differently from static
| (non-rotating) black holes.
| DiogenesKynikos wrote:
| The laws of physics are invariant under a change in linear
| velocity. If you take everything in the Universe and add a
| constant to its velocity, and then if you yourself add that
| amount to your own velocity, then everything will appear
| exactly the same.
|
| The laws of physics are _not_ invariant under rotation. If
| you take everything in the Universe and give it a nudge so
| that it 's spinning around a particular axis, things will
| change. For starters, everything will fly apart, unless you
| also create a force field that pulls everything towards the
| axis of rotation (with the force increasing linearly with
| distance from the axis of rotation).
|
| A technical way to describe this is to say that the laws of
| physics have Poincare invariance (or more properly, just
| Special Relativity has this invariance).[1]
|
| That's why linear momentum is viewed as a trivial property
| of a black hole, but angular momentum is not.
|
| 1. https://en.wikipedia.org/wiki/Poincar%C3%A9_group
| Ma8ee wrote:
| No. Simply put, the laws of physics will be described by
| different equations in a rotating frame of reference than
| in one that doesn't rotate, while it is impossible to
| distinguish two frames of reference that is just moving
| relatively to each other without any reference to the
| outside.
| [deleted]
| pfortuny wrote:
| AFAIK linear momenum depends on the choice of inertial
| reference frame, so you may assume it is 0.
| travisgriggs wrote:
| I watched the whole video.
|
| My current physics acumen is probably in the lower half of the
| average HN reader.
|
| I enjoyed AP physics in high school. Took the test, got a 4. I've
| been helping my wife back in school with half life decay (as much
| chemistry as physics) and relished that. As a Mechanical
| Engineering student, I got A's in my three required physics
| class. In short, I really liked physics. It helped me make sense
| of the world.
|
| I'm old enough, that quantum mechanics was not the public
| fascination it is now. Cold fusion was the big topic those days.
|
| Despite all of this early formative appreciation for physics, I
| have yet to really appreciate QM.
|
| It just has never helped me explain the world around me. And
| unlike many of the transcendental changes that occurred in the
| industrialized world as we got better and better at physics,
| whatever QM is supposed to do for me (it's supposed to have
| bigger application than the double slit thing, right?), isn't
| apparently obvious to me.
|
| The brief parts where Sabine is referring to QM particulars in
| the video, and when I skim the other articles and such I see on
| QM, always include a lot of phunky math, amusing names and
| symbols, and a sort of talk that sounds like convoluted
| philosophy, or an attempt to explain transubstantiation or the
| "mystery of the trinity."
|
| I was amused at the end of the video. There's a "keep your cake
| and eat it too" thrust. She clearly states a sort of
| collegiate/professional "you do you" support. At the same time
| she tells the viewer they don't need to pay attention or care
| about it. But if we the lay masses don't care, the PR that exists
| for the sake of securing funding to go on with these papers dries
| up. So in a round about way, she's saying "I support my
| colleagues wishes to continue to pursue these studies, but you my
| reader shouldn't bother to support them in any way, direct or
| indirect."
| marcosdumay wrote:
| > It just has never helped me explain the world around me.
|
| Hum... All of electronics, the entire modern chemistry, solid
| properties, gaseous state changes, how do you make sense of any
| of that without QM?
|
| (Of course, it's perfectly ok to not understand those if you
| don't want to. But then you can't claim that it's missing, just
| that you don't want to learn it.)
| paulpauper wrote:
| I don't think his statement is that unreasonable. the world
| is perceived and interfaced as macro yet the quantum is is
| what makes the macro. So you have to figure out where the
| macro becomes the quantum.
| bollu wrote:
| The math of QM underpins so much of modern technology, like
| transistors, MRIs, high precision clocks..
|
| I feel like there's been a humongous failure of science
| communication if the applications of QM aren't obvious to you
| :( I don't mean that in a mean spirited fashion, I really do
| feel despair that someone on HN who enjoyed physics wasn't
| shown how quantum physics has been the bedrock for so much
| technology!
|
| EDIT: quick list of places QM/quantum physics is used in the
| real world: https://scienceexchange.caltech.edu/topics/quantum-
| science-e...
| kungito wrote:
| Of course if QM is a current ly valid theory that it can be
| found in many of these examples but we don't really need to
| know about QM or the way it works to have a microwave oven or
| semiconductors. You don't use QM when modelling relevant
| things to get a semiconductor working, at least not the ones
| we were taught at college. My point being is I understand QM
| apparently underlies everything but do we ever really care? I
| did hear though that for current cutting edge semiconductors
| they have to take into account QM
| grendelt wrote:
| Just admit it, you kept losing your information.
| [deleted]
| formerkrogemp wrote:
| A few of my friends in school went into physics very starry eyed
| and excited. They worked in academia. Then, they worked for space
| startups and NASA. Now they work in "business intelligence" and
| the tech ad business. I do enjoy Sabine's writing and
| perspective. I miss my friends' aspirations and enthusiasm for
| physics and space.
| morelandjs wrote:
| She's exactly right. Any science discovery that's worth its salt
| is falsifiable. If you can't validate your results there's a
| problem. It's the responsibility of every theorist to make
| testable predictions, and to communicate to experimentalists how
| they might be tested.
|
| There's frankly not enough pressure within the theory community
| to disregard cagey theorists that actively avoid testing their
| predictions, or disregard the importance of testing in general.
| bsedlm wrote:
| This is a limitation of science.
|
| The issue I see, is how to continue to study such purely
| theoretical matters?
|
| Why should everything have to be testable (and thus,
| potentially developed into a marketable product)?
|
| It may not be science, but a lot of people still like to do
| that kind of theoretical work.
| tsimionescu wrote:
| Well, you can do maths research. That doesn't need to be
| testable, only self-consistent. However, number theorists
| don't come and say they've uncovered some grand mystery of
| the cosmos when they prove something about trans-finite
| numbers, unlike many theoretical physicists.
| morelandjs wrote:
| Exactly. A lot of amazing math has come out of string
| theory.
| morelandjs wrote:
| Here's the problem I see with it. Say you take multiple "top
| tier" theoreticians and task them with the same physical
| problem. Suppose they all make slightly different starting
| assumptions, and these assumptions lead to mutually
| incompatible conclusions. Which one is right? Who do we
| believe?
|
| The whole point of testing theories is there can only be "one
| truth". If you let theories run rampant without testing you
| end up in logically inconsistent chaos.
|
| All that said, theories should certainly be given time to
| grow when experimental validation is not immediately
| available. However, there's many in the community that take
| great liberty with that long leash to the detriment of
| physics progress.
| tappaseater wrote:
| Well Einstein-Podolsky-Rosen was published in 1935. Bell's
| Theorem was published in 1964. Bell's wasn't tested
| experimentally until 1972, by which time it was largely
| forgotten except for creative fellow who worked out a way to
| test it.
|
| I think having testability as a qualification for theory might
| not serve us well.
|
| It blows my mind how much we have deduced about black holes in
| 100+ years, yet it was only very recently that we could
| actually "see" one. Would hate to lose that.
| Zamicol wrote:
| I've always considered Bell's solution somewhat obvious.
|
| It wasn't team Einstein's responsibility to propose a
| solution, his motive was a rebuttal.
|
| The fact that it went unstated for 30 years, Einstein died in
| 1955, reflected poorly on team Heisenberg.
| mungal wrote:
| Sabine's niche seems to be a confident cynicism or learned
| skepticism and is a much appreciated addition to the space.
|
| I like Sabine's personality and the fact she stands in defiance
| of the status quo of scientific outreach, namely my two least
| favorite tropes: "science is fun" and "let me explain something
| using terrible metaphors because I fail to understand the math
| myself".
|
| Sabine, if you're reading this... please create more technical
| content.
|
| Maybe a companion video to your more general takes.
|
| One that shows the numerical side of things. Your experience and
| personality already lend itself to this effort.
|
| You say "the math is insufficient" show us the math! Show us how
| it's insufficient using numerical examples.
|
| Scientific outreach has a real "draw the rest of the owl" problem
| and I think Sabine is perfectly poised to fill the gap.
|
| There's a George Carlin quote I'll paraphrase ~"never talk down
| to your audience, they'll catch up eventually."
| squeaky-clean wrote:
| Check out the youtube channel Physics Explained. I don't think
| you can get much simpler than his videos yet still be numeric.
| They're great videos though, not pop-sci at all and his
| explanations are great. But don't expect something you can
| watch casually.
| paufib wrote:
| bsder wrote:
| > Sabine's niche seems to be a confident cynicism or learned
| skepticism and is a much appreciated addition to the space.
|
| I think Sabine has settled into a niche with a few other
| physicists of "If you don't even have a _hope_ of testing your
| theory, what 's the point? Let's direct those resources into
| things that can be tested sometime in the next century."
|
| Theoretical physics seems to have a few arenas where it has
| just completely left the realm of reality. It's not even like
| "Well, maybe we can test these in a few years when technology
| gets better" but more like "We would need 15 orders of
| magnitude more energy than exists in the universe to test
| this."
| mhh__ wrote:
| If you think numerical examples would help you probably need to
| read a quantum field theory book and understand that this is
| really complicated stuff.
|
| Physicists for the most part aren't talking down spiritually,
| they're just talking to the equivalent of a child.
| mungal wrote:
| I made sure to say "outreach" stead "education".
|
| I think it's a paradox to say "you need to be fully educated
| on a subject to engage with an explanation intended for lay
| people".
| sandpaper26 wrote:
| There's a wonderful textbook, I think by Griffiths, that
| starts from the premise that if you learn the math of quantum
| mechanics first (i.e. how to actually set up and solve
| relevant systems of equations) then it's much easier to learn
| the meaning and implications after. It gives you a lot of
| problems up front to give you a rock-solid grounding in
| numerical examples, and only in part 2 does he delve into
| what it all _means_.
| vmilner wrote:
| https://en.m.wikipedia.org/wiki/Introduction_to_Quantum_Mec
| h...
| peteradio wrote:
| Yes indeed, very early on it shows the equivalence of
| summing over position/momentum states. Depending on the
| desired answer one is much easier to calculate.
| mhh__ wrote:
| His book on elementary particles perhaps?
|
| I think there's a General Relativity book that does the
| same thing only with the schwarzchild solution, but I'm not
| sure who wrote it.
| rrss wrote:
| > Scientific outreach has a real "draw the rest of the owl"
| problem
|
| It seems like this is just the "you need to study the problem
| and it's dependencies for many years to understand the physics
| and mathematical details" problem. Which does not actually seem
| like much of a problem to be solved, just a reality.
|
| Your example in the other comment depends on linear algebra, so
| ~first year undergraduate of most technical fields. IMO that's
| fundamentally more accessible than the black hole information
| paradox, with its dependencies on general relativity and
| quantum field theory.
|
| I'm sure more technical videos and posts could be made about
| this, but how small would the target audience be?
| mungal wrote:
| I wonder if we're in agreement?
|
| The key word is 'numerical'.
|
| Maybe you've yet to see or do numerical analysis of both
| general relativity and quantum field theory but they are in
| fact both linear algebra.
|
| Which as you point out is "fundamentally more accessible".
| lkrubner wrote:
| General relativity is linear algebra? Has anyone called up
| Tullio Levi-Civita and told him that his services will no
| longer be necessary?
| mungal wrote:
| I've seen this sort of reactionary response in
| mathematics and music as well.
|
| When talking to a musical educator complaining about
| struggling students just starting out I'll say "I found
| it extremely helpful to paint the C major scale on my
| guitar when learning music theory."
|
| And they respond "Well what about chromatic 12 pitch
| atonal music?! What would Anton Webern say?!"
| TheOtherHobbes wrote:
| In GR terms, Levi-Civita is more like "This is a major
| scale and you need to know it" than serialism.
|
| Some subjects are _just plain hard_ and only accessible
| to smart persistent people.
|
| GR and QFT definitely qualify - but they seem to be warm
| up exercises compared to whatever Quantum Gravity will
| eventually become.
| sidlls wrote:
| Eh, no. The problem with your analogy is that the "not
| linear algebra" bits aren't esoteric, rarely practiced or
| used edge cases: they're the core of the mathematical
| model.
| wumpus wrote:
| As someone who has studied GR (at the grad school level)
| and music, no, that's a terrible analogy.
| mhh__ wrote:
| They're both what now?
| mungal wrote:
| https://en.m.wikipedia.org/wiki/Tensor
| pfortuny wrote:
| A tensor is a differential structure with pointwise
| linear properties. But the important thing is not the
| pointwise behavior but the differential nature of the
| "family of tensors in non-Euclidean space".
| mhh__ wrote:
| That's very weak
| pfortuny wrote:
| I guess you are mistaking the "local linear nature" of
| tensors for differential geometry. GR is certainly not
| "linear algebra".
| oefrha wrote:
| As a physicist who used to work on unifying QFT and
| gravity, no, QFT is not accessible _at all_ , to anyone.
| General relativity is kind of accessible to a non-physics
| student if they otherwise have a strong math background,
| which is like 0.001% of the population, optimistically.
| sonofaragorn wrote:
| All these topics are so advanced that even for someone
| trained in one it would take years to become proficient
| in the other.
|
| Source: I'm a Physics PhD
| wiz21c wrote:
| 0.001% is already about 800_000 people :-)
| rrss wrote:
| No, just because general relativity and quantum field
| theory use linear algebra does not mean they are linear
| algebra.
| noslenwerdna wrote:
| General relativity is not linear algebra. Just glancing at
| the underlying equations, you can see they are non linear.
| [https://en.wikipedia.org/wiki/Einstein_tensor]
|
| The same is true for quantum field theory. I'm curious why
| you're so confident that they are "in fact both linear
| algebra"
| WhitneyLand wrote:
| >Maybe you've yet to see or do numerical analysis of both
| >general relativity and quantum field theory
|
| I call you out. Don't think you've done either one after
| reading your comments.
| in3d wrote:
| I find PBS Space Time to be superior to her videos in pretty
| much every case.
|
| https://youtube.com/c/pbsspacetime
| gotaquestion wrote:
| > "let me explain something using terrible metaphors because I
| fail to understand the math myself".
|
| Some of these channels have millions of viewers, and the one I
| think you are referring to has 11M. Remember when the Reimann
| Zeta function summation of -1/12 was all the rage, or the
| Banach-Tarsky paradox? Google either of those and there are a
| dozen YouTube videos for each one. These are post-doctoral
| topics that become name-dropping buzzwords, I would never claim
| to understand these, yet people who watched the video do.
|
| Which seems like a lot what the internet has given us:
| information, not knowledge. To quote a speaker I saw at
| Siggraph in ~1996, "Information is not power, knowledge is
| power." This hit home. We've seen it from people reading WebMD
| in the 2000's and then trying to teach their doctors, to the
| crazy scientific ignorance about mask mandates today. All
| because of internet edutainment or in the worst-case
| misinformation.
|
| Anyway, yes, her article got cynical fast, but I think it was
| because she bounded with realism because plotted on the arch of
| technology evolution: it would take thousands of generations
| (even at an exponential pace) to create tech that can take
| actual measurements. That seems like good science to me.
| gus_massa wrote:
| I agree that most videos in YouTube simplify the problem too
| much or are just wrong. My recommendations anyway:
|
| * Mathologer: " _Ramanujan: Making sense of 1+2+3+... = -1
| /12 and Co._" https://www.youtube.com/watch?v=jcKRGpMiVTw
|
| * Vsauce: " _The Banach-Tarski Paradox_ "
| https://www.youtube.com/watch?v=s86-Z-CbaHA
|
| Each one is like half an hour long, but you may need to pause
| them and rewatch them a few times to understand the details.
| gotaquestion wrote:
| Yes, I've watched both of those. Mathologer is in the biz
| of math, Vsauce is in the biz of ka-ching.
| mardifoufs wrote:
| I don't think the vsauce channel is egregiously
| monetized. He sometimes does not upload for months or
| even years, and does not make the most clickbaity videos
| out there. He could've easily been much bigger than
| veritasium, in terms of monthly views, if he wanted to by
| just making the same type of videos as he used to do (
| the broad mishmash videos that I really really liked
| honestly).
|
| The fact that he didn't, to me, indicates he is obviously
| not in the business of making money.
| ramraj07 wrote:
| I am a fan of her work and videos but saying We will never
| make experimental progress on the black hole paradox for TEN
| THOUSAND years seems myopic at best. Does she not instantly
| realize how long that is? Unless we nuke ourselves out of it,
| I see us as an interstellar civilization easily within
| 100-200 years. That's being conservative. I'd be surprised if
| we don't have probes looking around the nearest black holes
| or even creating ones experimentally in double or triple
| digit years from today.
| edgyquant wrote:
| It isn't talking down to your audience to relate that
| mathematical logic to them in understandable ways. A lot of
| people are curious about physics or astronomy but don't have
| the time or energy to learn high level math to do so.
| mungal wrote:
| I'll add to this to give an example of someone who I feel is
| doing a great job of satisfying this very request in the field
| of mathematics: Timothy Gowers.
|
| His yt channel is an excellent resource of theoretical
| understanding through numerical methods.
|
| Here's my favorite series where he confirms/elucidates a
| "strange" theoretical fact with an explorative numerical style:
| https://m.youtube.com/watch?v=byjhpzEoXFs
|
| Simply superb content.
| morelandjs wrote:
| I'll just add that I appreciate her cynicism because there is a
| staggering amount of bullshit in the high energy theory
| community. Embracing creativity is absolutely paramount, but
| people need to grow up and accept their own theory failures
| when they occur.
| aeonik wrote:
| Completely agreed. I was skeptical about her at first. My first
| exposure to her was the panel interview hosted by PBS Space
| Time "Theories of Everything" https://youtu.be/N_aN8NnoeO0
|
| At first I thought she was biased because she was was so
| skeptical about almost every point during the discussion, but
| her logic and arguments were all so solid and well thought out,
| they were impossible to ignore.
|
| I checked out her channel, and she was the first YouTuber that
| I found who actually explained the syntax of Quantum Mechanics
| equations and what Kets are. https://youtu.be/ctXDXABJRtg
|
| More detailed content would be greatly welcomed from her.
| qsdf38100 wrote:
| She seems to be after some hidden truth that "scientists" are
| not telling us. I'd be more appreciative of her insights if
| those were not implying we've been lied to. She should
| consider that 1. Being wrong is ok, doesn't mean someone's
| lying. 2. Maybe she is wrong. 3. Interpretations of quantum
| mechanics are fun and there's nothing to be angry at. So I'm
| a bit skeptical about her skepticism, it doesn't sound
| constructive to me.
| lumost wrote:
| She makes very specific points on what can and can't be
| reasonably treated as a scientific problem. Her main
| concern appears to be that much physics research and
| funding has deviated towards mathematical philosophy. Work
| which _may_ be correct, but is untestable and ultimately
| unscientific.
| AnimalMuppet wrote:
| I read the article. I've read other articles of hers as
| well. And I don't read her that way at all.
|
| What she primarily is, is someone who insists on
| experimental data as an anchor for physical theories. She's
| not totally against theory that isn't backed by experiment
| (despite her last paragraph or two), but given multiple
| competing theories that cannot be experimentally verified,
| she is unwilling to accept any one of them as "the truth".
| I don't think she's wrong in that.
| johnny22 wrote:
| this is exactly my problem with the way she does things.
| billfruit wrote:
| Doesn't Feynman Lectures book III explain kets fairly well?
| hobo_mark wrote:
| Feynman was a YouTuber?
| mbaytas wrote:
| Feynman most probably would be a youtuber if he were
| alive.
|
| Even posthumously he's been one of the most popular
| educators on youtube.
| sdenton4 wrote:
| Have you read 'Surely You're Joking Mr Feynman'? Dude was
| a youtuber physicist in a world where youtube didn't
| exist.
| 8note wrote:
| Somebody put his lectures up on YouTube a long time ago.
|
| If "person who's content is available on YouTube"
| qualifies one as a YouTuber, then yes
| bee_rider wrote:
| I think generally "YouTuber" is taken to mean somebody
| who is building particular YouTube personality/brand
| thing.
|
| But even if we want to be very general and just parse it
| using default English, the -er suffix would mean someone
| who is doing something. I believe it would be more
| accurate to say Feynman was YouTubed.
| AnimalMuppet wrote:
| How did you go from "Feynman Lectures Book III" to
| "Youtube"? billfruit was asking about a _book_.
| IG_Semmelweiss wrote:
| Here is my first exposure to her. Its an in depth discusson
| on her own book. She does strike me as very cynical.
|
| https://www.econtalk.org/sabine-hossenfelder-on-physics-
| real...
| zone411 wrote:
| Her video on the Simulation Hypothesis was very poor
| https://lech.substack.com/p/sabine-hossenfelders-video-
| the-s....
| wildmanx wrote:
| > Sabine's niche seems to be a confident cynicism or learned
| skepticism and is a much appreciated addition to the space.
|
| While I also appreciate a healthy dose of skepticism, and in
| weaker moments I can also get very cynical, this is not a very
| constructive attitude to science or life in general. If we were
| all doing science like that, we'd not have gotten anywhere.
|
| As mentioned elsewhere in this discussion, a "solution" will
| not only consist of a theory that "solves" the problem in the
| sense that Sabine described, but even propose experiments that
| can actually be executed within a time frame (and budget) in
| order to validate the theory. Just because her colleagues (and
| Sabine herself) have failed at that so far should not be a
| reason to give up. With that attitude, there wouldn't be much
| science left today.
| conformist wrote:
| I'm not sure whether her cynicism is helpful or not. But,
| style aside, it seems like it's mainly a function of whether
| her subfield as a whole skews optimistic?
|
| It seems like her impression is that (parts of) the high
| energy theory community are too optimistic to an extent where
| they unintentionally or intentionally deceive the public (who
| are ultimately funding science through taxes).
|
| If that's correct, perhaps it can be beneficial for science
| as a whole to provide a counterbalance?
| johnny22 wrote:
| >> It seems like her impression is that (parts of) the high
| energy theory community are too optimistic to an extent
| where they unintentionally or intentionally deceive the
| public (who are ultimately funding science through taxes).
|
| This is a fair take. I really appreciate it. Sometimes i'm
| too cynical about the motivations of the folks being
| cynical :)
| Ar-Curunir wrote:
| Yeah, cynicism is actually terrible for science, and as a
| result many scientists aren't overly cynical. I think it's
| something that happens as folks mature: they tend to look for
| the positives in papers, rather than the negatives.
|
| This has certainly been my experience in cryptography: as a
| student you often start off proposing schemes which get
| broken by your advisor/collaborators (not out of malice, but
| just because broken schemes are broken), and so you learn to
| react to novel ideas with "how is this broken?". However, as
| you mature, you realize that all new correct ideas arise from
| the ashes of many broken attempts, and so your reaction
| slowly changes to "how can I fix this?", leading to an
| overall more positive outlook on both your work as well as
| others' work.
| ramraj07 wrote:
| You are partially correct, absolute cynicism would mean
| that you would see the possibility that any hypothesis can
| be wrong before testing it so you'd just not do any
| experiment at all. So you do need to be optimistic.
|
| But that's not what most scientists do today. They are
| cynics masquerading (even to themselves) as optimists. They
| have preprogrammed themselves to never even think of a
| question that has a good chance of failing, modern academia
| has collectively programmed them all to only ask questions
| that never have a real chance of being false to begin with.
| So just softball niche questions or in the case of the
| videos topic, reformulate the question in a way so that the
| answer doesn't fundamentally solve the real problem. Both
| because the real problem might be unsolvable and also
| because if you solve the problem then you have fired
| yourself from yoUr job.
|
| Now you might think I and Sabine and others are just
| shitting on scientists doing the work, but many of us are
| only doing so after wasting decades with this establishment
| and giving up. Perhaps you can see that for yourself
| earlier and save yourself a lifetime.
| willis936 wrote:
| To me it seems more like she failed at creation and found an
| easier path forward in arson.
|
| In a world where FUD spreads faster than truth and not everyone
| is an expert in every topic: her work does as much, if not
| more, harm than good. Particularly in fields she is not an
| expert in.
| alophawen wrote:
| I love Sabine. I find her one of the few sober and rational
| voices on youtube.
|
| Maybe it is her direct and confrontative way that scares off some
| americans? I'd say she comes out like a sterotype german :-)
| senectus1 wrote:
| is it rude to post the TL;DR?
|
| >And that's why I stopped working on the black hole information
| loss paradox. Not because it's unsolvable. But because you can't
| solve this problem with mathematics alone, and experiments are
| not possible, not now and probably not in the next 10000 years.
| fijiaarone wrote:
| Unobservable phenomena by hypothetical objects with
| contradictory arbitrary rules that have no effect on reality.
| azernik wrote:
| A quibble - these objects are not just hypothetical. We have
| images and other evidence of some particularly large ones.
|
| It's the exact rules that are hypothetical.
| ncmncm wrote:
| But we cannot observe Hawking radiation without having, on
| hand, a black hole small enough to be hotter than the CMB
| -- or that can be enclosed and protected from it, and the
| enclosure itself cooled below it, _and_ in a vacuum so hard
| as not to any have atoms to fall in.
|
| All tall orders.
| The_rationalist wrote:
| jvanderbot wrote:
| Do all black holes with the same mass and other 'hairless'
| parameters (momentum, etc) have the same temp and therefore
| radiation emissions? If so, can we remotely measure mass from
| this?
| PaulHoule wrote:
| Except in the real world for any black hole we observe (stellar
| mass or larger) that temperature is much lower than the cosmic
| microwave background so that you won't see it.
|
| A stellar black hole floating out between the galaxies would
| not be evaporating now but rather slowly gaining energy from
| the CMB. The universal will have to expand for a long time
| before it gets cooler than black holes.
| jvanderbot wrote:
| But, my main question: Do they all have the same temp, given
| all other main parameters?
| WJW wrote:
| That depends on if they have hair or not, but nobody knows
| whether they do and it would be extremely impractical to
| experimentally verify such a thing. That's what the article
| is all about.
|
| If they don't have hair then yes, you should be able to
| estimate mass by measuring their temperature. You would
| also need to know how far it is though, so that you could
| compensate for redshift.
| jvanderbot wrote:
| OK, that makes sense.
|
| In reading TFA I was just kind of blown away that temp,
| mass, angular momentum, etc, are all so closely tied
| together.
| tsimionescu wrote:
| Note that they are so closely tied together _for black
| holes_ , not necessarily for other types of objects.
| Black holes in the GR description are probably simpler
| than some elementary particles even.
|
| However, it's important to note that the GR description
| is itself not exactly self-consistent, as the curvature
| is divergent at the center of the black hole (it is
| infinite, I believe?).
| Ma8ee wrote:
| No, small black holes are hotter than big black holes.
| tsimionescu wrote:
| Black holes of the same mass (and angular momentum and
| charge) have the same size.
| Ma8ee wrote:
| Of course. I apparently read the question to fast.
| snowwrestler wrote:
| If you change assumptions to solve a big problem, you don't
| necessarily need to measure the big problem to check the
| assumptions. General Relativity itself was first confirmed with a
| relatively simple measurement of star displacement during a solar
| eclipse.
|
| The "real solution" to the black hole information paradox will be
| one that solves the paradox AND provides a "small" way to test
| the change in assumptions that creates the big solution. This is
| definitely worth looking for IMO.
| im3w1l wrote:
| Totally agree. And it may even be that the small thing comes
| first. That we happen to observe some weird shit in a different
| domain, and once we shuffle assumptions around to fit
| observations we get black holes for free.
| nemothekid wrote:
| > _provides a "small" way to test the change in assumptions
| that creates the big solution_
|
| Isn't this the problem. Unless we discover some primordial
| black holes, all black holes we currently know about are way
| too cold, and will be way too cold for billions of years, to
| test anything.
|
| GR predicted black holes, but GR wasn't about black holes, and
| there were plenty of other things you could test.
| zackmorris wrote:
| This is a good post with all of the right reasons to be
| skeptical. However, with the really fringe stuff like this, I
| feel that the answers could come through intuition.
|
| On that note, her central premise is that we can't study black
| holes. But I'm feeling more and more convinced that the universe
| itself is inside of a black hole. If that's the case, then maybe
| we can study the inside after all.
|
| On a whim, I searched for "hawking radiation hubble constant" and
| stumbled onto a bunch of stuff like this (the Download PDF button
| works):
|
| https://www.preprints.org/manuscript/202101.0017/v2
|
| I'm not a physicist, but if I assemble a bunch of ideas, I can
| make a bunch of insights like: if black holes evaporate faster as
| they shrink, then maybe galaxies slipping outside of our
| observable universe is causing it to become less massive, which
| is increasing its rate of expansion. Someday we may see
| everything shooting away from our reference point faster and
| faster until we ourselves pop, like reversed spaghettification.
|
| But then again, that doesn't seem quite right, because the
| galaxies slipping away from us faster than the speed of light
| probably don't experience anything catastrophic themselves. And
| also the galaxies might not actually be moving away, just more
| space has been constructed between us and them like a balloon
| stretching. I feel like without a solid understanding of this
| process, it's going to be hard to understand black holes.
| visionscaper wrote:
| I don't know much about the black hole information loss problem
| and I do like Sabine's skepticism. However, saying it has no use
| to work on mathematical solutions in this area is taking it one
| step too far. Maybe, based on the solutions other (indirect)
| experiments can be devised, maybe it will help solve other
| Physics, mathematics or engineering problems in the future.
| sytelus wrote:
| TLDR; There exist many solutions, none of them experimentally
| verifiable and hence the pointless debate continues.
| spekcular wrote:
| This seems like a fully general (and somewhat unconvincing)
| argument against doing theoretical physics. The key paragraphs
| are:
|
| "What's going to happen with this new solution? Most likely,
| someone's going to find a problem with it, and everyone will
| continue working on their own solution. Indeed, there's a good
| chance that by the time this video appears this has already
| happened. For me, the real paradox is why they keep doing it. I
| guess they do it because they have been told so often this is a
| big problem that they believe if they solve it they'll be
| considered geniuses. But of course their colleagues will never
| agree that they solved the problem to begin with. So by all
| chances, half a year from now you'll see another headline
| claiming that the problem has been solved.
|
| And that's why I stopped working on the black hole information
| loss paradox. Not because it's unsolvable. But because you can't
| solve this problem with mathematics alone, and experiments are
| not possible, not now and probably not in the next 10000 years."
|
| First, let's grant that no experimental evidence will be
| forthcoming in thousands of years. (It's conceivable to me that
| some astronomers will get lucky and provide some indirect
| evidence of some sort, but ignore this for now.)
|
| Why do we believe that this problem can't be solved, or at least
| profitably investigated, with mathematics (and physical
| intuition, and the rest of the experimental evidence we have
| about black holes - it's definitely not "mathematics alone")? At
| least in principle, one can imagine that there is a finite set of
| possible solutions (corresponding to dropping various
| assumptions, as she mentions earlier in the article), and all but
| one of those can be ruled out a priori via mathematical
| inconsistencies, a contradiction with physical evidence from non-
| black hole phenomena, or other undesirable properties.
|
| Maybe there are special features of the black hole information
| problem that make this impossible. But this overall mode of
| mathematical investigation is how theoretical physics works and
| has always worked. Einstein discovered general relativity by
| tweaking assumptions and deducing the theory was likely to be
| true because it resolved various issues, but we had no direct
| test [edit: of gravitational waves] for about 100 years. It would
| have been unfortunate if he concluded the problem was pointless
| to work on because no experimental evidence would manifest within
| his lifetime.
|
| (Example problem fixed by Einstein:
| https://aether.lbl.gov/www/classes/p10/gr/Precessionperiheli...)
| tsimionescu wrote:
| I don't think Sabine claims that we can't possibly discover a
| testable theory that _also_ solves the black hole information
| loss paradox. However, that doesn 't mean that investigating
| the black hole information loss paradox problem itself is a
| good way of arriving at that theory.
|
| Theoretical physics has always been most successful when
| investigating proven experimental inconsistencies - the
| measured invariance of the speed of light in different rest
| frames for special relativity, for example, or the photovoltaic
| effect or ultraviolet catastrophe for QM.
|
| Investigating other effects of quantum gravity and arriving at
| a theory that can be tested here on Earth would potentially
| lead to a testable theory that also provides insights into
| black holes. Or, perhaps investigating the measurement problem
| could lead to a more fundamental non-linear theory (which QM
| would be only an approximation of) that would be consistent
| with information loss.
|
| These are both much lower hanging fruit than worrying about
| effects that we have no hope of measuring (note that we can't
| even prove that burning a book doesn't lose information - it's
| just easier to explain where the information could, in
| principle, be going, but it's still impossible to measure with
| current or foreseeable technology).
|
| Your example of gravitational waves is exactly on the money for
| this. If instead of focusing on the inertial & gravitational
| mass equality "coincidence" and on gravity's effect on light,
| Einstein had tried to come up with a model for gravitation
| waves as the only thing he investigated, chances are he would
| not have arrived at GR. Perhaps he would have arrived at some
| SR + gravity waves theory that would have taken 100 years or
| more to disprove, and missed all the other insights.
| spekcular wrote:
| Was ultraviolet catastrophe really an experimental
| inconsistency? It seems to best understood as a theoretical
| inconsistency: The theory predicts a diverging (infinite)
| value, which we know would be wrong regardless of what the
| experimental evidence is. It's a mathematical problem, not an
| empirical one. You also give the example of "the measured
| invariance of the speed of light in different rest frames,"
| but Einstein claims SR was motivated by the invariance of
| Maxwell's equations (a theoretical consideration), not e.g.
| Michelson-Morley. So it sure seems that investigating
| theoretical inconsistencies has motivated a lot of good work.
|
| I agree that, practically speaking, studying the black hole
| information paradox might not be so productive. Maybe there
| are special features of the problem that make it difficult to
| investigate productively through theoretical considerations
| alone. But this is not how I read Hossenfelder. Taking her
| blog post literally, she seems to be against theoretical
| investigations of any phenomenon (any inconsistency, etc.)
| where experimental tests aren't forthcoming. I think this is
| ridiculous.
|
| Maybe she doesn't actually believe this, but then she needs
| to make an argument specifically about the black hole
| information paradox and why this particular problem is
| unproductive, not launch a broadside on non-empirical
| reasoning more generally.
| tsimionescu wrote:
| > Was ultraviolet catastrophe really an experimental
| inconsistency? It seems to best understood as a theoretical
| inconsistency: The theory predicts a diverging (infinite)
| value, which we know would be wrong regardless of what the
| experimental evidence is.
|
| Well, that theory also predicts that the universe can't
| exist for very long, which is a pretty big experimental
| inconsistency.
|
| > You also give the example of "the measured invariance of
| the speed of light in different rest frames," but Einstein
| claims SR was motivated by the invariance of Maxwell's
| equations (a theoretical consideration), not e.g.
| Michelson-Morley.
|
| Well, Maxwell's equations were relatively well
| experimentally verified by other experiments, so there were
| good reasons to at least tentatively accept their
| prediction of a constant speed of light* in any rest frame
| as a given. Even if the Michaelson-Morley experiment was
| not big on his mind, it was still relatively clear that
| this type of experiment _could_ be performed with
| technology already available at the time, as the speed of
| light had been measured with pretty good precision already
| for a few decades.
|
| So, SR was not some highly speculative theory based only on
| extrapolating other theories, as solutions that only
| address BHILP but not other problems of QM/GR are
| currently.
|
| * or at least of electro-magnetic radiation, not sure when
| it became accepted light was EM radiation relative to the
| SR paper
| spekcular wrote:
| > Well, that theory also predicts that the universe can't
| exist for very long, which is a pretty big experimental
| inconsistency.
|
| Sure, but I don't need to appeal to this fact to know
| there's a problem that must be solved. The infinities are
| enough.
|
| > Well, Maxwell's equations were relatively well
| experimentally verified by other experiments, so there
| were good reasons to at least tentatively accept their
| prediction of a constant speed of light* in any rest
| frame as a given. Even if the Michaelson-Morley
| experiment was not big on his mind, it was still
| relatively clear that this type of experiment could be
| performed with technology already available at the time,
| as the speed of light had been measured with pretty good
| precision already for a few decades.
|
| But again, even if MM couldn't have been performed,
| Einstein still would have had good theoretical reasons
| (consistency with Maxwell's equations) to posit SR. And
| indeed, this was the path the discovery seems to have
| actually taken.
|
| > So, SR was not some highly speculative theory based
| only on extrapolating other theories, as solutions that
| only address BHILP but not other problems of QM/GR are
| currently.
|
| Sure, but this is a difference in degree, not in kind.
| You accept that theoretical arguments for new phenomena
| that are not directly testable (at present) are
| acceptable if they're convincing enough. The question
| about BHILP under this view (which I agree with) is then
| about how convincing the theoretical arguments are.
|
| Hossenfelder, taken literally, suggests that no
| theoretical arguments will ever good enough in the
| absence of empirical evidence.
| tsimionescu wrote:
| > Sure, but I don't need to appeal to this fact to know
| there's a problem that must be solved. The infinities are
| enough.
|
| By that logic, you shouldn't believe in black holes / GR
| at all, right? In practice, we can always replace
| infinities with some arbitrarily large numbers that don't
| grow all the way to infinity because of yet-unknown
| physics (probably quantum gravity, in the case of black
| holes).
|
| > But again, even if MM couldn't have been performed,
| Einstein still would have had good theoretical reasons
| (consistency with Maxwell's equations) to posit SR. And
| indeed, this was the path the discovery seems to have
| actually taken.
|
| I don't think this would have been promising if the MM
| experiment seemed a hundred years away, and in general I
| don't think SR would have been as compelling in that
| case. I suspect we would have still had arguments about
| an aether if experiments on the speed of light in
| different inertial frames had remained beyond reach.
|
| > Sure, but this is a difference in degree, not in kind.
| You accept that theoretical arguments for new phenomena
| that are not directly testable (at present) are
| acceptable if they're convincing enough. The question
| about BHILP under this view (which I agree with) is then
| about how convincing the theoretical arguments are.
|
| Sure, it's a difference in degree in the end. The
| plausibility of having an experiment "soon" is the degree
| here. I don't think that Hossenfelder would argue that if
| an experiment is only possible 2 years from now, or maybe
| even 20 years from now, you shouldn't work on some
| theoretical subject. But, when that time horizon
| stretches well beyond your lifetime and the lifetime of
| your students, it's perhaps time to reconsider.
|
| I also know for sure she doesn't have a problem with
| doing theoretical research where you don't yet know how
| something would be testable, as long as you plan to
| define an experiment as well. She explains this in some
| detail when discussing her own work on superdeterminism -
| where she plans to first define a concrete model, and
| then come up with experiments which could invalidate that
| particular model - instead of giving up a priori because
| "there's no known way to test such a theory".
| spekcular wrote:
| > By that logic, you shouldn't believe in black holes /
| GR at all, right? In practice, we can always replace
| infinities with some arbitrarily large numbers that don't
| grow all the way to infinity because of yet-unknown
| physics (probably quantum gravity, in the case of black
| holes).
|
| I don't see how this follows. The ultraviolet catastrophe
| (or other divergences) says we have to fix something, it
| doesn't say that we should choose a weird ad hoc fix.
|
| > I don't think this would have been promising if the MM
| experiment seemed a hundred years away, and in general I
| don't think SR would have been as compelling in that
| case.
|
| It probably wouldn't have been as compelling, I agree.
| Don't get me wrong; the gold standard is empirical
| evidence. But the invariance arguments and procession of
| mercury would be grounds for taking it seriously.
| Einstein's argument for the theory depends only weakly on
| MM.
|
| > Sure, it's a difference in degree in the end. The
| plausibility of having an experiment "soon" is the degree
| here. I don't think that Hossenfelder would argue that if
| an experiment is only possible 2 years from now, or maybe
| even 20 years from now, you shouldn't work on some
| theoretical subject. But, when that time horizon
| stretches well beyond your lifetime and the lifetime of
| your students, it's perhaps time to reconsider.
|
| This seems like an unnecessarily narrow view of what
| constitutes worthwhile physics. First, because the
| experimentalists are very clever, and there's no knowing
| what indirect tests they might propose. But mainly
| because, if we can make theoretical progress on an
| important question, why not do that (even if empirical
| data is not forthcoming)? This view suggests that a
| physicist in 1915 (or 1925, etc.) should not try to work
| out properties of gravitational waves, for example, which
| seems obviously ridiculous to me. (The direct
| confirmation came about 100 years later.) If the
| theoretical motivation for doing so is solid, why not?
|
| I agree that BHILP paradox is probably a different case,
| one where we might really have no shot of saying
| something useful theoretically. But this requires getting
| into the specific details of BHILP. These general
| statements about what is and isn't good physics because
| of near-future testability all seem clearly suspect.
| tsimionescu wrote:
| > I don't see how this follows. The ultraviolet
| catastrophe (or other divergences) says we have to fix
| something, it doesn't say that we should choose a weird
| ad hoc fix.
|
| My point was that we have accepted GR even though we know
| it implies a divergence at the center of a black hole,
| which we know exists. We assume the math is probably
| mostly right, we do have a huge curvature at that point,
| but it can't be literally infinite. We assume that if we
| had a slightly better theory (probably quantum gravity)
| that would fix the divergence without changing too much
| else.
|
| By contrast, we couldn't say "the theory that predicts
| the ultraviolet catastrophe is mostly right, we're just
| missing a tiny piece to stop the divergence", because we
| had good experimental evidence that atoms don't collapse
| almost very quickly at all. So, while the infinity alone
| was a motivation to look for a better theory, it was the
| extreme contradiction with experiment that motivated a
| fundamentally different theory instead of an adjustment.
|
| > But the invariance arguments and procession of mercury
| would be grounds for taking it seriously. Einstein's
| argument for the theory depends only weakly on MM.
|
| Looking this up some more, I had a mistaken impression.
| The independence of the speed of light from the velocity
| of the source was already relatively well established by
| 1905 - in fact, this was part of the motivation for
| Maxwell's equations from 1865. Maxwell's equations had
| been thoroughly tested and were well accepted, especially
| because of experiments by Hertz in 1900. However, the
| dominant concept was still that light is a wave in the
| luminiferous ether - but several attempts to measure the
| interaction with this ether had produced null results.
| Even what we now call the Lorentz factor had been
| experimentally measured through experiments on the speed
| of light in a moving medium (then thought to be a drag
| coefficient between the medium and the ether).
|
| Einstein then came up with the idea that constancy of the
| speed of light should apply in any reference frame, not
| just some special frame defined by the ether. That means
| that not only is the speed of light independent of the
| speed of the source (which isn't that strange for a
| wave), but it's also independent of the speed of the
| _observer_. This was only experimentally proven much
| later, in 1932, by the Kennedy-Thorndike experiment.
|
| Still, SR followed from theories that were well proven
| empirically, and had obvious experiments that could
| falsify it.
|
| > This view suggests that a physicist in 1915 (or 1925,
| etc.) should not try to work out properties of
| gravitational waves, for example, which seems obviously
| ridiculous to me.
|
| Well, I think here there is a difference between trying
| to work out consequences of an otherwise well-established
| theory (such as working out exactly how gravitational
| waves would look like in GR, or arguing based on
| Maxwell's equations) and trying to come up with a new
| theory that modifies existing ones (such as grand
| unification or some solutions to BHILP).
| photochemsyn wrote:
| The mathematical development of non-Euclidean geometry required
| for Einstein's general relativity took place over the previous
| century and really changed people's thinking. From Poincare
| 1905, chapter on non-Eucliden space, the conclusion was then:
|
| > "In other words, the axioms of geometry (I do not speak of
| those of arithmetic) are only definitions in disguise. What,
| then, are we to think of the question: Is Euclidean geometry
| true? It has no meaning. We might as well ask if the metric
| system is true, and if the old weights and measures are false;
| if Cartesian co-ordinates are true and polar co-ordinates
| false. One geometry cannot be more true than another; it can
| only be more convenient."
|
| https://www.gutenberg.org/files/37157/37157-pdf.pdf
|
| Prior to those developments by Riemann etc., people like Kant
| claimed space was flat, as there was no other possible
| mathematically consistent geometrical option:
|
| https://www.ln.edu.hk/philoso/staff/sesardic/Kant.html
|
| This is all comparable to a quote in the posted article:
|
| > "But. There are many different ways to resolve an
| inconsistency because there are many different assumptions you
| can throw out. And this means there are many possible solutions
| to the problem which are mathematically correct. But only one
| of them will be correct in the sense of describing what indeed
| happens in nature. Physics isn't math. Mathematics is a great
| tool, but in the end you have to make an actual measurement to
| see what happens in reality."
|
| It would seem, then, that the study of black hole information
| loss is more in the area of mathematics at present then it is
| in physics, much as is the case with string theory (for which
| Fields Medals have been awarded, but not Nobel Prizes in
| Physics). It might however go the way of non-Euclidean geometry
| and Einstein's general relativity at some point in the future.
| jfengel wrote:
| Except that if there is a way to do the experiment, it can only
| be found by doing theory. Push the symbols around until
| something new falls out.
|
| Maybe it will. Maybe it won't. But it seems weird to dismiss it
| as fundamentally unsolvable.
|
| I happen to agree that it's not likely to be solved, and even
| if it is won't be terribly useful. It gets funding only because
| it captures people's attention, for being "deep".
|
| I'd love it if science funding were more rational, but that's
| hardly confined to fundamental physics. If it were up to me
| we'd fund theoretical physics AND a lot of other things, and
| stop funding a lot of expensive things I dislike. But plenty of
| people disagree, and the resulting process is inevitably
| irrational.
|
| I see no value in shaking my tiny fists at one particular set
| of scientists over that.
| goatlover wrote:
| Without empirical evidence, I'd always be skeptical that we
| really knew what was going in inside some unobservable region
| of spacetime, even if the math all works out and agrees with
| what's observable. Theoretical physics divorced from the need
| for experimental results gives us endless string theories. It's
| the same arguing for some interpretation of QM. You might have
| the most convincing arguments for there being many worlds
| making up the wavefunction, but without some way to confirm
| that, it's metaphysics. And one mights well go all the way and
| embrace Tegmark's mathematical universes or some simulation
| argument. But that isn't science anymore.
|
| I don't care how good the math looks. Reality isn't obligated
| to confirm to some human aesthetic about beauty or simplicity.
| You have to first make some metaphysical assumption that the
| universe has to be that way. And the only way we can really
| know is to have empirical evidence.
| spekcular wrote:
| If I told you "some unobservable region of spacetime" had to
| display a certain feature, or there would be a mathematical
| contradiction, would you accept that?
|
| If not, would you endorse believing in gravitational waves on
| the basis on the success of the rest of GR, before they were
| experimentally confirmed?
| FartyMcFarter wrote:
| > This seems like a fully general (and somewhat unconvincing)
| argument against doing theoretical physics.
|
| Not exactly, since this quote definitely doesn't apply to all
| theoretical physics:
|
| > experiments are not possible, not now and probably not in the
| next 10000 years.
| spekcular wrote:
| Einstein had no positive evidence to suggest direct tests of
| gravitational waves would ever be possible. His arguments
| were entirely about consistency and theoretical parsimony, as
| are the arguments about the black hole information paradox.
| If we take the view that we shouldn't work on physics we
| can't test, or can't test for a very long time, then we are
| led to the conclusion that Einstein shouldn't have worked on
| gravitation waves. I find that conclusion untenable.
| jacquesm wrote:
| I think that author is simply saying why they don't want to
| work on this problem any more, not necessarily that nobody
| else shouldn't be working on it anymore. Einstein did what
| he wanted for his own good reasons, he was right and
| extremely insightful on most occasions and wasn't driven to
| 'put his name in the history books' but because he was
| working on interesting problems. Once the problems no
| longer seem that interesting it's time to move on.
| spekcular wrote:
| I disagree. The author is very pointedly saying that
| research on this problem is worthless and a waste of
| time. See the last paragraph, for example.
| jacquesm wrote:
| Which contains this bit: "I am not talking about this
| because I want to change the mind of my colleagues in
| physics."
|
| That seems to be pretty clear to me.
| spekcular wrote:
| The full paragraph is: "Why am I telling you this? I am
| not talking about this because I want to change the mind
| of my colleagues in physics. They have grown up thinking
| this is an important research question and I don't think
| they'll change their mind. But I want you to know that
| you can safely ignore headlines about black hole
| information loss. You're not missing anything if you
| don't those articles. Because no one can tell which
| solution is correct in the sense that it actually
| describes nature, and physicists will not agree on one
| anyway. Because if they did, they'd have to stop writing
| papers about it. "
|
| It's hard for me to read this is as anything other than
| "I am not talking about this because I want to change the
| mind of my colleagues in physics [because they're too far
| gone]." That is, she believes the research is worthless
| and the problem shouldn't be investigated. She just
| doesn't think she can convince people of this.
| jacquesm wrote:
| But what she believes may simply be wrong. It's just one
| persons opinion and regardless of motivations ascribed to
| others people need to justify their choices to themselves
| and themselves alone but some people apparently need to
| do so publicly because otherwise it somehow doesn't
| count.
|
| This is just one interesting sub-problem in physics and
| if you choose for a career in theoretical physics you
| know that not everything that you set out to do you will
| achieve and I suspect that in this particular case it is
| a let down of fairly large proportions.
|
| So you get a lot of internal struggle to justify the
| choice, the sunk cost issue is massive and your
| colleagues are going to go and continue without you. All
| that needs to be justified to the 'self', both on the off
| chance that they _will_ come up with a solution when you
| gave up as well as about all of the time that you now
| feel that you have wasted.
|
| And in the realm of self justification 'I will stop
| working on this problem because I no longer feel like
| working on it' is a lot harder to sell to the ego than 'I
| will stop working on this problem because I feel that it
| can't be solved in a meaningful way'.
|
| I'm fine with it, either way, I've seen enough people
| struggle with career choices made in their 20's when they
| were in their 40's not to recognize the symptoms: you
| have reached the halfway mark in your life, what do you
| have to show for it? And if the answer is 'not much' then
| that can be a problem. But it doesn't have any value for
| others, that's all just window dressing and ego-
| placating.
| raverbashing wrote:
| Gravitational waves are just a consequence of the Einstein
| field equations _for which he had experimental evidence
| for_ (the light bending from the sun during the eclipse)
| canjobear wrote:
| GR made predictions that were testable at the time and
| Einstein was keenly interested in testing them. See
| https://einsteinpapers.press.princeton.edu/vol5-doc/609
| spekcular wrote:
| Yes, but gravitational waves themselves were not
| testable. To get from the confirmation of the other
| predictions to belief in gravitational waves, for which
| you had no direct evidence (until recently), you need to
| apply exactly the non-empirical criteria (parsimony,
| consistency, etc.) that Hossenfelder (taken literally)
| seems to think is not sufficient for doing theoretical
| physics in the absence of direct evidence.
| tsimionescu wrote:
| Then you are misunderstanding her position. She is not
| claiming that a convincing solution to the BHILP is
| impossible. If you came up with a theory of quantum
| gravity that can be measured in other regimes and that
| also solves the BHILP, perfect: we now have good reasons
| to believe that your theory is indeed THE solution to
| that problem.
|
| However, if you come up with a theory that makes the
| exact same predictions as QM and GR except for the BHILP,
| then your theory is not very interesting, since we will
| never be able to test this theory, and there are other
| inconsistencies between QM and GR that you haven't
| solved, so we can't just rest on our laurels and say
| physics is over.
| spekcular wrote:
| I don't think I misunderstand her position. She seems to
| take the position you give:
|
| "However, if you come up with a theory that makes the
| exact same predictions as QM and GR except for the BHILP,
| then your theory is not very interesting, since we will
| never be able to test this theory, and there are other
| inconsistencies between QM and GR that you haven't
| solved, so we can't just rest on our laurels and say
| physics is over."
|
| I think this is wrong. There are non-empirical reason
| reasons we might prefer the new theory to the old one.
| For example, we know QM are GR are inconsistent, so if I
| give you a parsimonious, consistent theory that captures
| both QM and GR in the appropriate limits, then that's a
| great reason to prefer it. In principle, we could prove
| theorems (and some theorems of this form have been
| proved) that pin down the possible resolutions of the
| GR/QM inconsistency. If we tighten the net so that only
| one theory remains, then obviously we should choose to
| believe that theory.
|
| Now, will that actually happen? I don't know. But merely
| waving your hands and going "not testable" is not enough,
| because we all accept that mathematical consistency ought
| to have a huge influence on theory choice. You need to
| make some argument about BHILP specifically saying that
| theoretical arguments will never produce productive
| physics.
| tsimionescu wrote:
| > For example, we know QM are GR are inconsistent, so if
| I give you a parsimonious, consistent theory that
| captures both QM and GR in the appropriate limits, then
| that's a great reason to prefer it.
|
| Absolutely agree. But BHILP is not the only
| inconsistency, so if you only solve that one and leave
| the others, but complicate the math or add other elements
| that can't be tested, it's not a particularly compelling
| theory.
|
| So, why not work directly on the other inconsistencies,
| which might be directly testable, and see if this one
| disappears that way?
|
| To be clear, when I say other inconsistencies, I am
| referring to things like making QFTs work in a non-flat
| spacetime, and/or reconciling the linearity of QM
| (without Born's rule) and the non-linearity of GR.
| spekcular wrote:
| > So, why not work directly on the other inconsistencies,
| which might be directly testable, and see if this one
| disappears that way?
|
| These are not mutually exclusive options. The community
| works on both.
|
| Again, I agree that so far, practically speaking, work on
| BHILP has not been super compelling. I take issue with
| the stronger stance that Hossenfelder seems to take, that
| we know _a priori_ that work on BHILP will be worthless
| because experimental data is not forthcoming. ( "And
| that's why I stopped working on the black hole
| information loss paradox. Not because it's unsolvable.
| But because you can't solve this problem with mathematics
| alone, and experiments are not possible, not now and
| probably not in the next 10000 years.")
| CyanBird wrote:
| The error is that, simply because, even if true, that an
| experiment can't be done for the next 10000 years, this
| doesn't mean that someone else could think of a different
| experiment that could fulfill the initial prerequisites and
| provide a workable outcome/answer
|
| I think the writer is being too fatalistic on that simply
| because he/she can't come up with a workable experiment, then
| no one else can. I think that simply because of all the
| nonlinearities of "life", we are bound to have someone else
| come up with maybe a different experiment which answers the
| question, just picture that there are several, several ways
| to prove General Relativity with experiments not just "the
| one"
| hanselot wrote:
| tsimionescu wrote:
| At least for cosmic black holes, there is no way to measure
| the correlation of hawking radiation with the objects
| composing the black hole unless you can detect and store
| information about all objects going into the black hole and
| all radiation coming out, and then look for correlations
| between these. Even assuming you could store and process
| this literally stellar amount of information, you would
| have to be extraordinarily lucky for the correlation to
| arise immediately. More likely, you would need to do this
| for the entire lifetime of the black hole, and only after
| it's (mostly) evaporated could you run the analysis. Even
| granted the galaxy-sized computer that could do so, you
| would need to wait a few thousands of billions of years or
| more to reach that state.
| matt_kantor wrote:
| > Einstein discovered general relativity [...] but we had no
| direct test for about 100 years.
|
| General relativity was tested by the Eddington experiment in
| 1919: https://en.wikipedia.org/wiki/Eddington_experiment
|
| (I mostly agree with your overall point, this is just a minor
| quibble.)
| spekcular wrote:
| Sorry, I meant direct tests of gravitational waves. I think
| that claim is accurate.
| jeremyjh wrote:
| Why is that one thing particularly important? The point is
| that general relativity had immediately testable
| predictions. It wasn't just math.
| spekcular wrote:
| General relativity predicts gravitational waves. For the
| theory to be correct, gravitational waves need to exist.
| You haven't fully confirmed the theory experimentally
| unless you confirm that consequence.
| mannykannot wrote:
| This is a useless way of looking at things - even the
| task of just listing all the implications of a theory is
| probably unbounded, and if, at any point, you assume the
| correctness of another theory... If you are only
| maximally skeptical in some matters, then you are being
| inconsistent.
| spekcular wrote:
| Sure. But this is a huge, incredibly novel prediction.
| It's not some trivial matter.
| [deleted]
| mannykannot wrote:
| You can make the claims of your original post (and
| arguably more effectively) without the subjective (and
| rather idiosyncratic) view that GR was in some sort of
| indeterminate level of credence until the detection of
| gravity waves.
| spekcular wrote:
| Sorry, I wrote poorly. I don't mean to say that GR or
| gravitational waves were in some sort of indeterminate
| level of credence. I mean to say that our credence in
| gravitational waves in the absence of experimental
| confirmation is justified by exactly the kinds of non-
| empirical evidence that Hossenfelder rejects. So it's
| clear that she's being too restrictive in what she
| believes is worthwhile theoretical physics.
| jeremyjh wrote:
| That doesn't mean that he didn't have ideas for testable
| predictions of the model. It implied all kinds of things,
| some of which he had not even thought of (like Black
| Holes). Its quite a lot different to propose a model with
| some novel predictions that you can validate, and to
| propose a model that can never be tested in any form at
| all.
| spekcular wrote:
| Some predictions of the model were tested soon after
| Einstein published the theory. Others, like gravitational
| waves, were not. Yet people still believed in
| gravitational waves long before they were empirically
| confirmed.
|
| I don't see any possible basis for that belief (at the
| time) other than arguments based on non-empirical reasons
| like consistency and parsimony. (That is, it would be
| strange if other predictions of the model worked out but
| this one didn't.) Yet it is exactly this kind of
| theoretical reasoning that Hossenfelder, taken literally,
| seems to reject (in the absence of experimental data).
|
| I'll also note that any other solution of the black hole
| information paradox has to be consistent with the the
| rest of what we know about physics, and any future
| empirical observations. So it can't be completely
| untethered from reality; it makes testable claims in this
| way. Further, it's not clear such solutions can never be
| directly tested, or will never be found to imply novel
| testable consequences.
| Beldin wrote:
| As that article mentions, data quality was abysmal. I once
| saw a remark about the error bars being larger than the
| supposed effect - though o cannot find it and think that
| might be overly harsh.
|
| The 1922 test of starlight deflection by the Sun was much,
| much more accurate. And it did take about 100 years to detect
| gravitational waves. Though the earliest test was probably
| the perihelion of Mercury, which I think was covered in the
| original GR paper.
| hotpotamus wrote:
| That seems to be the way of cutting edge science. The data
| that Hubble gathered that showed the expansion of the
| universe is considered terrible by today's standards, but
| it was enough to prove it.
| meroes wrote:
| Einstein is a great example where his intuition served him well
| for most things, but not quantum mechanics. And it's not his
| fault. He was worried spooky action at a distance was opening
| up physics to be nonlocal, which he feared would ruin
| scientific progress for practical reasons.
|
| Quantum mechanics is also something without experiment no one
| would come up with in a million years.
|
| Einstein was right to fear science anti-thetical to the
| enterprise. If QM were a tiny bit more nonlocal our ability to
| do experiments would be much more limited.
|
| His wisdom about the limits of science was correct but QM was
| something no wisdom at the time could foretell without
| experiments.
|
| Maybe you aren't aware but there are probably 50 or more
| interpretations of QM by now. And it's even worse on the string
| theory side.
|
| I fear we have always relied on experiments, and going even 100
| years without one is cause for alarm.
| jasonwatkinspdx wrote:
| > Quantum mechanics is also something without experiment no
| one would come up with in a million years.
|
| You may find the book Quantum Computing since Democritus an
| interesting read. It's motivating them is how the ancient
| greeks might have deduced the basics of QM.
| kalimanzaro wrote:
| That's fine. One can also do essentially the same work in a
| mathematics department without the miasma of subjective or
| historical notions of what progress means. I mean,
| mathematicians are perfectly fine with producing theorems,
| proofs and even conjectures. Physicists secretly wish for the
| community's (not just the committee's) validation also.
|
| Well yes, Einstein found physicists insufferable as well and
| preferred to hang out with Godel. That doesnt mean you should
| go straight and transfer to Logic
| cryptonector wrote:
| Sonic black holes have been studied experimentally. They are only
| weak analogs of actual black holes, so how much light they can
| shed on real black holes, I don't know, but it does seem to me
| that as long as they do have insights to reveal, we can't say
| that work on black hole information loss is purely mathematical.
| It's also possible that pure mathematical solutions will yield
| predictions that can be tested w/o a black hole.
|
| So I'm a bit skeptical of her take on this subject, though if
| work in this space is unrewarding and there's more rewarding work
| to do elsewhere, then that makes sense. But then, I am not a
| physicist!
| https://interestingengineering.com/sonic-black-holes-and-the-
| information-paradox
| Linda703 wrote:
| fpoling wrote:
| One has to be skeptical even about the whole notion of the
| temperature of a black hole and existence of Hawking radiation.
|
| In a book from 1927 Richard Tolman tried to generalize
| thermodynamics to General Relativity. One of the most interesting
| of his results was that in GR thermal equilibrium required a
| temperature gradient that depended on the gravitational field.
| Tolmen's result is still sometimes discussed but it is not
| settled if he was wrong or right.
|
| The catch is that if his reasoning was correct, then the black
| hole horizon from a point of view of external observer should
| have the temperature of 0K which in turn implied no Hawking
| radiation.
| wumpus wrote:
| I did a search on arxiv and I see people are writing a small
| number of modern papers on that exact topic. Are you familiar
| enough with them to summarize?
| computator wrote:
| > _You're not missing anything if you don't those articles._
|
| I love the irony that something is missing in her closing remark.
| Almost makes me wonder if it was intentional.
| daxfohl wrote:
| Here's what I've never understood. From an outside perspective
| the black hole will evaporate before the thing falls in. Thus a
| thing can never fall in. From its perspective the hole will emit
| more and more intense radiation and finally evaporate just before
| it hits the horizon.
|
| If true, I think you can go even further and say no black hole
| can completely form; the collapsing matter just gets
| exponentially closer to being fully black until the effect of the
| Hawking radiation outweighs the gravitation, but it all
| evaporates before going fully black. No?
|
| (This latter part assumes there's some Hawking radiation or
| equivalent from pre-black holes as well).
|
| Now, I assume the pre-Hawking radiation would be unitary, since
| the only reason Hawking radiation is not unitary is because BHs
| don't have information, but pre-black holes are not black holes.
| So doesn't that solve the info paradox? Without resorting to
| holographs and whatnot? Where's the error?
| [deleted]
| PaulHoule wrote:
| See
|
| https://en.wikipedia.org/wiki/Firewall_(physics)
|
| vs
|
| https://en.wikipedia.org/wiki/Black_hole_complementarity
| daxfohl wrote:
| Sure, but the paradoxes listed on those pages go away because
| _the black hole never fully exists_. The mass inside any
| volume is always _just short_ of what would be required to
| make a black hole. And so _of course_ we can expect to see
| crazy quantum effects at the boundaries, just like any other
| massively dense celestial object. However it 's hidden behind
| insane time dilation to anyone outside.
|
| Going a bit further, it could even explain dark energy
| (Granted, I'm way out of my depth here): One outcome of
| General Relativity is that a large enough object of any
| density is a black hole (a black hole the size of Saturn's
| orbit need only be the density of water). Thus if we assume
| the universe is infinite and self similar, mass would have to
| constantly expand in order to avoid black holing.
| peterburkimsher wrote:
| Could a black hole exist in the same universe as a magnetic
| monopole?
|
| https://en.wikipedia.org/wiki/Magnetic_monopole
|
| If energy is related to matter by E=mc2, then the
| electromagnetic field of the monopole would also be
| diminished by a black hole, if one truly exists. But there
| might only be a single monopole.
|
| "Standard models of inflation solve the "monopole problem"
| by arguing that the seed from which our entire visible
| Universe grew was a quantum fluctuation so small that it
| contained only one monopole."
|
| https://www.newscientist.com/article/mg14419512-600-do-we-
| li...
|
| Scientifically I'm way out of my depth, but perhaps there's
| a perfect universe on the other side of the black
| hole/white hole/wormhole. Or perhaps the perfect design is
| already here, and when we find bugs, we should be working
| to improve the world around us to make it better over time.
| I know I can't do that alone, but by some miracle,
| technology seems to be helping.
| Fellshard wrote:
| This may be somewhat tangential, and if it is too much so, then
| ignore this and move along.
|
| Isn't the key axiom - preservation of information - a
| presupposition, and not a formally evidenced law? As best I can
| tell, it's mostly been assumed as a required premise for a larger
| axiom - the eternality of matter.
| twhb wrote:
| The article does say it's "experimentally extremely well
| confirmed".
| Strilanc wrote:
| Here's a relevant blog post: https://scottaaronson.blog/?p=3327
| 'Is "information is physical" contentful?'
|
| In quantum mechanics, breaking unitarity (which implies
| conservation of information) is akin to breaking the rule in
| statistics that probabilities have to add up to 100%. You get
| things like a 300% chance of rain or a 90% chance of [null
| reference exception]. It's hard to overstate how deep down it
| is and how many things depend on it.
| chubot wrote:
| Interesting, this is a slightly weaker form of a theory not being
| falsifiable. Any theory won't be falsifiable in the next 10,000
| years!
|
| I think it's a good idea to make these distinctions.
| debdut wrote:
| Maybe in some years we create a small black hole, and since
| radiation is inversely proportional to mass, not only it will
| emit measurable emissions, it will pop out of existence or go
| through it's lifetime pretty quickly. Hence experiments will be
| possible and the paradox solution can be verified
| fasteddie31003 wrote:
| I am skeptical of any black hole research because it cannot be
| currently tested. I recently went down the rabbit hole on how the
| Event Horizon Telescope (EHT) got a picture of a black hole
| because this could be used as experimental evidence of how a
| black hole works. After looking into how the EHT was calibrated,
| I am extremely skeptical of their results. I'm not an
| Astrophysicist, but I have a lot of understanding of statistical
| causality and Scientific Philosophy. The EHT processes that made
| the image of a black hole break a lot of the scientific methods
| IMO. The algorithms they use to make the image of the black hole
| were never tested against a known celestial body to calibrate the
| algorithms. They took a "a posteriori" approach to their imaging
| algorithms, which do not produce accurate results. I noticed
| their unscientific approach to the imaging algorithms after when
| I watched "Black Holes: The Edge of All We Know", which is a
| first-hand account on how the EHT developed their black hole
| image. They were literally testing different imaging algorithms
| to find the one that looked most like a circle. The correct
| method would be to calibrate their imaging algorithms against a
| known celestial body to make sure their techniques produced
| comparable results from other instruments. Then they should have
| taken their calibrated imaging algorithms and gave it data from
| the M87 black hole, but they skipped the hole calibration step
| and went right into imaging the black hole, which makes me very
| skeptical of their results.
| meroes wrote:
| My understanding of cosmology and astronomy is there is an
| inherent "ladder", nesting of assumptions, or indirect argument
| structure. Like, IF the Moon is a sphere, then by the shadows
| Earth leaves upon it during eclipses, Earth is a sphere. This
| reasoning came before Aristotle knew the Earth was sphere.
|
| https://youtu.be/7ne0GArfeMs?t=632
|
| This is still a way to do science. I'm willing to believe the
| experimenters dealt with the inherent novelty in a scientific
| way. What do you mean known celestial body?? We've only ever
| "been" to 2. We don't get to run all the experiments you'd
| like. As long as the process is self-correcting, it works. You
| have not shown this method to be uncorrecting. Better and
| better standards are used to strengthen these claims. And it is
| expected some degree of future corrections will occur. That's
| the nature of the beast.
| docandrew wrote:
| I feel like the use of astronomy and cosmology to model and
| understand sub-microscopic processes seems a little...
| backwards? Frankly, I'm ignorant of both but my gut feeling
| tells me it's a bit of a scientific dead end. Would love to
| hear why I'm wrong or if anyone else more educated than I am in
| this area shares the same suspicions.
| wumpus wrote:
| > The algorithms they use to make the image of the black hole
| were never tested against a known celestial body to calibrate
| the algorithms.
|
| This is not true, as is much of the rest of your comment.
| Please read the papers, they say everything that the
| collaboration did.
| fasteddie31003 wrote:
| I've taken hours and read
| https://iopscience.iop.org/article/10.3847/2041-8213/ab0c57 .
| My take away was they did a good job calibrating their
| signals, but I've never seen anything about calibrating their
| imaging algorithms. They have not calibrated the whole
| imaging stack. My skepticism is in the algorithms, not the
| signals.
| wumpus wrote:
| You read the paper about calibrating the signals, that's a
| reasonable takeaway.
|
| There's a different paper about how the 4 independent
| algorithms were tested to make sure they did the right
| thing with simulated data: ring, crescent, disk, double
| point source.
|
| That's the process that you had an incorrect takeaway from
| the documentary about. The filmmaker is a member of the
| collaboration and was highly involved in the imaging.
|
| First M87 Event Horizon Telescope Results. IV. Imaging the
| Central Supermassive Black Hole https://iopscience.iop.org/
| article/10.3847/2041-8213/ab0e85/...
|
| You'll have to follow the footnotes to find out the ages of
| these algorithms; CLEAN was invented well before I first
| used it in 1985, and I first ran into maximum likelihood in
| 1987 or so.
| fasteddie31003 wrote:
| Thanks. I will read this paper.
| rrss wrote:
| When you say the "whole imaging stack," which one do you
| mean?
|
| EHT imaged M87 with four teams working independently using
| different methods. Each of those teams used algorithms that
| were published and validated before the EHT results were
| published.
| fasteddie31003 wrote:
| Did the 4 teams create their algorithms before getting
| the observation data and not modify them at all after
| seeing the results from the first run of their
| algorithms? Or was there data and algorithm tweaking to
| get the results that they wanted?
| dane-pgp wrote:
| drcode wrote:
| I share your skepticism about the image, the problem is that
| without spending months learning the science & tech there is no
| way to substantiate our skepticism.
| fasteddie31003 wrote:
| Just show me a calibration image of a know celestial body
| using the exact same algorithms and I'll be satisfied.
| lupire wrote:
| It doesn't really matter. You are talking about a thing
| that severely distorts light and gravity. There is no real
| human-visible picture of it.
| BurningFrog wrote:
| Well, if it was nearby, we would see _something_. A
| camera _would_ capture an image.
|
| Perhaps our brains would not do well understanding the
| actual object producing the picture though.
| mc4ndr3 wrote:
| I thought Susskind solved this.
| fancyfredbot wrote:
| Reminds me of the phrase "not even wrong"
| https://en.m.wikipedia.org/wiki/Not_even_wrong
| DangitBobby wrote:
| Doesn't the idea of "randomly emitted radiation" contradict the
| concept of "reversal" itself? If you know enough about a system,
| anything that appears random within it actually turns out to be
| determinstic. So I don't understand how a black hole can be said
| to emit "random" radiation to lose information on the first
| place.
| lupire wrote:
| Non-newtownian/non-classical/non-relatistic Quantum effects are
| truly random. That's the core axiom of what makes "quantum"
| mechanics not Newtonian/classical/relativistic. It's
| fundamentally different from Newtownian statistical mechanics.
|
| Hawking radiation is purely random.
| bmacho wrote:
| > Non-newtownian/non-classical/non-relatistic Quantum effects
| are truly random. That's the core axiom of what makes
| "quantum" mechanics not Newtonian/classical/relativistic.
|
| Bohmian mechanics[1] (which is a model of QM) is fully
| deterministic, and Born rule emerges from the fact that we
| don't know some information. QM (equations, experiments) is
| fully consistent with a world, where the perceived randomness
| of a measurement is the exact same random, as in coin flips.
|
| For additional properties that QM does not satisfy (because
| there are known counter examples) see https://en.wikipedia.or
| g/wiki/Interpretations_of_quantum_mec...
|
| [1]: https://en.wikipedia.org/wiki/De_Broglie-Bohm_theory
| tsimionescu wrote:
| Note that Bohmian mechanics (the actual mathematical
| formalism) is not consistent with Special Relativity,
| unlike regular Quantum Mechanics. It's not proven that it
| can't be made consistent, and some are still working on
| that, but so far it has remained elusive. This means that
| it's not really "an interpretation" of QM, it's a slightly
| different theory, one that is worse at predicting observed
| reality...
| rssoconnor wrote:
| Indeed. Wake me up when Bohmian mechanics can predict the
| anomalous magnetic dipole moment.
| bmacho wrote:
| Fair point. Well it proves that non-relativistic QM
| (which is not supported by the experiments, and is
| inconsistent with our best and most useful theories) is
| not proven to be "truly random", at least the math does
| not imply it, so disproves parent's statement.
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