[HN Gopher] Speculation that wormholes and entanglement are two ...
___________________________________________________________________
Speculation that wormholes and entanglement are two aspects of the
same thing
Author : prostoalex
Score : 86 points
Date : 2022-10-11 15:36 UTC (7 hours ago)
(HTM) web link (www.nytimes.com)
(TXT) w3m dump (www.nytimes.com)
| kdavis wrote:
| nathan_compton wrote:
| I've got a PhD in physics but am not a theorist. I do, however,
| maintain an interest in this material and I must confess that
| when you dig pass the gloss that Susskind typically puts on the
| "quantum mechanics == gravity" spiel the actual theoretical case
| seems pretty distant/vague (to say nothing of the fact that there
| is nothing like experimental support for anything at all having
| to do with this because the experiments are presently
| impossible).
|
| What all this comes down to is a "mere" correspondence between
| some equations governing the way entanglement develops in time
| and the way some other gravitational systems evolve in time in a
| very specific sort of set up universe which is quite different
| from our own. Lots of physical phenomena have similar dynamical
| laws. Given the tenuousness of ADS/Cft and the differences
| between that imaginary universe and our own in number of
| dimensions and structure of spacetime, I think the assertion that
| these two phenomena supervene upon a shared ontological substance
| of some kind is provocative but hardly anything I'd write a New
| York Times article about. I mean for the lay reader this is
| basically bullshit which is more likely to confuse than
| illuminate.
|
| That said, if this kind of reporting sparks the interest of a
| young physicist out there, I guess its mostly harmless.
| daveslash wrote:
| As a Lay Reader, about the only thing I understood was the last
| sentence of your second paragraph. Thank you.
| pdonis wrote:
| _> if this kind of reporting sparks the interest of a young
| physicist out there, I guess its mostly harmless_
|
| I'm not sure I agree. If reporting like this funnels more young
| physicists into doing this kind of research, which has been
| going on for decades without making any successful experimental
| predictions, then I don't think it's harmless.
|
| Not only that, but this kind of reporting has a subtext:
| Science is the Authority. Even when Science tells you what
| seems like obvious nonsense. And _that_ pernicious effect goes
| far beyond a few young physicists.
|
| That is not to say that there aren't scientific claims that
| seem highly counterintuitive to the lay person, but which are
| nevertheless true. There are. But _those_ claims are nailed
| down by massive quantities of experimental evidence that
| matches the predictions of the models to many decimal places.
| The speculative claims discussed in this article have _no_
| evidence to support them. Big difference. But you 'll never
| find that out by reading these kinds of articles.
| random314 wrote:
| Einstein's relativity was purely theoretical when it was
| accepted world wide based on abstract principles.
|
| So, your characterization of how modern physics works is
| completely wrong.
| pdonis wrote:
| No, your claim regarding the historical facts is completely
| wrong.
|
| If by "relativity" you mean _special_ relativity, nobody
| used it for anything when it was published. The first real
| use of it theoretically was to explain the Compton effect
| in 1921, based on experimental results. It took another
| decade or so for it to be routinely used, mainly due to its
| success in explaining the fine structure of atomic spectra
| and in developing quantum field theory.
|
| If you mean _general_ relativity, the first event that
| could be said to have gotten it "accepted world wide" was
| the 1919 eclipse expeditions organized by Eddington, which
| confirmed the GR prediction of bending of light by the Sun.
| And even then acceptance of it was still limited (see
| below).
|
| Also, even before that, GR was known to correctly predict
| the extra precession of Mercury's perihelion, which could
| not be explained by Newtonian gravity. So that was a piece
| of evidence for GR that was known before it was published.
|
| Note that even _after_ the 1919 eclipse expedition and the
| 1921 explanation of the Compton Effect, relativity was
| still considered too "out there" to justify a Nobel Prize;
| when Einstein got the prize in 1922 the Nobel committee
| specifically _excluded_ relativity from the scientific work
| by Einstein that was the basis for it.
| zethus wrote:
| > The speculative claims discussed in this article have no
| evidence to support them.
|
| Can you highlight which claims that you find to be
| speculative without evidence? There's a mix of existing
| theories that are being actively studied in theoretical
| physics (holographic cosmology), and some claims that the
| author seems to call out in rhetorical question. I get that
| either will whoosh over the lay person.
| pdonis wrote:
| _> There 's a mix of existing theories that are being
| actively studied in theoretical physics (holographic
| cosmology), and some claims that the author seems to call
| out in rhetorical question._
|
| All of those are speculative claims without evidence to
| support them.
| zethus wrote:
| I'd argue that in the case of AdS/CFT correspondence,
| they've been mathematically proven to be _possible_.
| Doesn't mean that it is true. We also don't have all of
| the answers to AdS/CFT questions to prove a holographic
| universe theory with utmost certainty. I would, however,
| agree that evidence could have been presented in the
| article, but I'm guessing the target audience for this
| piece may have never clicked into an array of academic
| papers.
|
| The classical wormhole as an extreme fold in spacetime is
| mathematically _possible_, but given what we've observed
| in the universe, extremely unlikely to naturally occur.
| pdonis wrote:
| "Mathematically possible" is a _much_ lower bar than
| "has evidence to support it". Yes, AdS/CFT is
| mathematically consistent, as are classical GR wormhole
| models. But there is no evidence to support either.
|
| _> I would, however, agree that evidence could have been
| presented in the article, but I 'm guessing the target
| audience for this piece may have never clicked into an
| array of academic papers._
|
| If you know of any scientific papers that present
| _evidence_ for AdS /CFT (or for wormholes, for that
| matter), please post links. I'm not aware of _any_ such
| papers.
| zethus wrote:
| Ah I understand your argument now and can agree we are on
| the same page. Can't say I know of any empirical/observed
| evidence either. I don't believe AdS/CFT can be used to
| make predictions of precise accuracy beyond serving as a
| toy model to reshape other physical observation.
|
| To get off the tangent, I've backed up the comment chain
| and am thinking about your original comments on the
| harmfulness of articles like this. At first I shared OP's
| sentiment that it is generally harmless, but the more I
| think about it, the more I take your stance. Curious what
| your thoughts are on exposing more people to theoretical
| physics sans popsci buzzword articles?
|
| For anyone else who's following this thread, I would
| recommend checking out "The Trouble with Physics" https:/
| /www.goodreads.com/book/show/108939.The_Trouble_with_...
| jemmyw wrote:
| Would also recommend Sabine Hossenfelder for some similar
| views on the path physics is taking / dangers of popsci
| https://www.goodreads.com/book/show/36341728-lost-in-math
|
| I've also enjoyed her YouTube videos that have knocked
| down a lot of my popsci derived thoughts.
| pdonis wrote:
| _> Curious what your thoughts are on exposing more people
| to theoretical physics sans popsci buzzword articles?_
|
| It's a great thing to try to do; I try to do it myself as
| a contributor to Physics Forums [1], for example.
|
| I'm not sure how much good books like _The Trouble With
| Physics_ actually do as far as exposing more people to
| physics sans popsci, because, while they might point out
| issues with how _speculative research_ in physics is
| done, they don 't actually _teach_ any physics.
|
| I personally would recommend Feynman's books for the
| layman, such as _QED: The Strange Theory of Light and
| Matter_ or _The Character of Physical Law_ , or _Six Easy
| Pieces_ (followed by _Six Not So Easy Pieces_ ), as ways
| for people to get at least some exposure to physics
| without popsci buzzwords. IMO even those books are
| limited, because you can't really understand physics
| without actually doing the math and solving some actual
| problems. But they're still way better than popsci
| articles (or, for that matter, popsci _books_ like those
| of Brian Greene or Michio Kaku).
|
| [1] https://www.physicsforums.com
| elefanten wrote:
| My immediate reaction to the headline was "oh, so NYT is now
| adding pop-sci clickbait to their repertoire?"
|
| Given all the other ways in which they've degenerated and
| embarrassed themselves in the last decade, I supposed they were
| bound to start doing this one too.
| LeftHandPath wrote:
| Hah... Maybe they've figured out that most of their readers
| are the same pseudo-intellectuals that will misunderstand
| things like Schrodinger's Cat and refer to it like magic,
| quietly hoping that other people will look up to them as all
| the wiser for having referenced it. Like a bartender I met a
| while ago that confessed to me that he and his wife
| interpreted quantum mechanics in a way that borders on
| religious, using it to discredit the concept of free will
| altogether.
|
| > Take gravity, add quantum mechanics, stir. What do you get?
| Just maybe, a holographic cosmos.
|
| Something tells me I'll be hearing a lot of confused
| misinterpretations of this over the next few days... A lot
| like the confusion over entanglement after this year's Nobel
| prize.
| TechBro8615 wrote:
| Have you considered why the best explanations that the
| field of physics can offer are all interpretations? Maybe
| it's because there is a lot we don't know, and the
| patchwork of scientific theory we've built up iteratively
| over centuries is leaking in places for reasons we don't
| understand.
|
| If you accept this, then it should be hard to mock someone
| who offers their own interpretation, since none of us know
| the answer to so many fundamental questions underpinning
| the physical universe in our cosmological plane of
| existence. At best, you knew more than he did about what we
| don't know.
| peteradio wrote:
| > Have you considered why the best explanations that the
| field of physics can offer are all interpretations?
|
| Or you can look at the maths but I doubt you would want
| to do that... Anytime you dumb something down, something
| is lost. If you try to build back from something that's
| dumbed down then you get a mess.
| vkou wrote:
| The best explanations that the field of physics can offer
| are systems of equations. Which make a lot more sense
| than the eli5 woo that popular science turns it into.
| LeftHandPath wrote:
| That is true and a much needed check. Thank you.
| tayo42 wrote:
| confessed is an interesting word choice? the bartender was
| being somehow deceptive about how they present their
| interpretation of quantum mechanics normally?
| [deleted]
| notfed wrote:
| IMO, GPT-3-like articles like this are no different from blog
| spam recipe websites.
|
| What even is the point of this article? What is the mind
| bending secret? The holographic principle? Wormholes?
| Entanglement? It's unclear what the title was referring to, but
| none of these things are news. There's not even a well defined
| recipe at the end; we're just left with some kind of pop-
| physics stew.
| [deleted]
| pndy wrote:
| > What even is the point of this article?
|
| Harvesting the data from those who clicked on this link -
| business as usual
| crazygringo wrote:
| That's the thing that sucks about titles. Editors choose
| them, the journalist has zero control over them, and they
| test different variations on the site and then settle on the
| one with the most clickthroughs.
|
| Definitely lots of cases of Op-Ed contributors, especially,
| unhappy with seemingly borderline misleading titles given to
| their pieces.
|
| I don't mind it too much as a reader, but it can suck as a
| contributor because everyone thinks they're your words.
| MilStdJunkie wrote:
| The piece feels a bit fluffy, but I agree that if it excites a
| new generation, a new bunch of physicists with a new way of
| looking at things, it's completely worth reading.
|
| On the other hand, I feel like it really missed the boat when
| it comes to the relation of entanglement to other properties of
| the macro universe. The notion that "geometry of spatial
| dimensions as emergent from networks of entanglement" is such
| an evocative idea that I don't understand how people aren't
| thinking about it all the time.
|
| What if certain systems are in fact in the same "place", even
| if they appear to be light years apart? What does "appear to be
| apart" even mean?
|
| To overuse an adjective, it's evocative. I do realize my
| understanding is barely that of a sparse layman, but it's still
| a fun mental toy to play with.
| andrewflnr wrote:
| Vague, sure, but does physics have anything better to offer
| when it comes to quantum gravity? Granted I'm biased as a (lay)
| fan of ER=EPR. And I don't entirely disagree with you; the NYT
| is probably not helping here and maybe shouldn't have waded in.
| adastra22 wrote:
| There are lots of quantum gravity theories. Take your pick.
| The problem isn't so much that we don't know how to reconcile
| QM with GR, but that there are many ways to do it and we
| don't know which is physical.
| andirk wrote:
| Adding gloss to a topic without leaving the realm of truth can
| be helpful in inciting interest, as you mention. Similarly, Dr.
| Michael I. Jordan of UC Berkeley describes in no uncertain
| terms that the phrase "Artificial Intelligence" is misleading
| in the field of the same name [1]. He basically says our AI
| thus far is recommendation engines and a self driving car.
|
| Is the glossy, somewhat simplified discussion of quantum
| mechanics == gravity == anti-god particle also misleading? I'm
| still trying to wrap my mind around the 10th grade Algebra's
| imaginary number [?]-1 .
|
| [1] https://youtu.be/EYIKy_FM9x0?t=864
| pas wrote:
| regarding [?]-1, the mystery is a bit simpler than with
| physics, because with math it is what it is, and there's no
| arguing about how real the math is :)
|
| that said, just as in physics we went from the concept of an
| atom (meaning an undividable whole) to a big ball of nuclear
| soup with protons and neutron and bound electrons raving
| around, then even further to noticing an even crazier
| confluence of chaos of quarks and gluons constantly churning
| in the nucleus, like that in math we went from integers to
| reals to complex numbers to saying hold my beer and "dividing
| number fields with irreducible polynomials" (see algebraic
| extension) and discovering all kinds of madness.
|
| in physics we used mightier and meaner matter smashers, in
| maths we used ... well, a similar amount of brute force of a
| certain kind, the kind that solved problems, rules of square
| roots be damned. and then it turns out that the rule was
| different all along, and congratulations now you have even
| more complicated numbers, the complex ones.
|
| just as in physics there's the always gnawing question of
| "okay, but what explains that small blip in the data?"
| there's the one in math about "okay, sure, that question is
| so simple-looking it's outright ridiculous/dumb, but how come
| nobody was able to answer it in decades/centuries? what if
| ...?"
|
| https://www.youtube.com/watch?v=-XCFQe2WVhw
| WhitneyLand wrote:
| As someone with a physics background does this sound right?
|
| From the article:
|
| _According to Einstein's general relativity, the information
| content of a black hole or any three-dimensional space -- your
| living room, say, or the whole universe -- was limited to the
| number of bits that could be encoded on an imaginary surface
| surrounding it._
|
| I thought this was more according to the Bekenstein bound than
| GR.
| pdonis wrote:
| _> I thought this was more according to the Bekenstein bound
| than GR._
|
| It is. The article is most certainly _not_ a good source from
| which to try to learn any actual physics.
| kevinventullo wrote:
| _"... hardly anything I 'd write a New York Times article
| about."_
|
| Given that NYT devotes an entire section to the goings-on of
| old money New Yorkers, I'm not sure the bar is all _that_ high.
|
| And hey sometimes coincidences are just that, but other times
| they can lead to profound theories. I'm reminded of Monstrous
| Moonshine for which Borcherds earned the Fields Medal in 1998:
| https://en.m.wikipedia.org/wiki/Monstrous_moonshine
|
| _The term "monstrous moonshine" was coined by Conway, who,
| when told by John McKay in the late 1970s that the coefficient
| of q (namely 196884) was precisely one more than the degree of
| the smallest faithful complex representation of the monster
| group (namely 196883), replied that this was "moonshine" (in
| the sense of being a crazy or foolish idea). Thus, the term not
| only refers to the monster group M; it also refers to the
| perceived craziness of the intricate relationship between M and
| the theory of modular functions._
| account-5 wrote:
| For a complete layman this sounds cool. Can someone with proper
| knowledge weigh in and tell me if this is non-sense or not?
|
| EDIT:
|
| Nevermind, other comments are clearing things up for me.
| pantulis wrote:
| This is pop-sci over speculative theoretical physics. Whether
| it makes sense to "popularize" this stuff or not, I think it
| makes for a great mind bending and fun read --also generates
| incoming traffic. So why not?
| random314 wrote:
| None of the HN commentors have a background in theoretical
| physics. These are low quality bike shedding comments.
|
| The ny times article itself is of a much higher quality. The
| holographic principle has been established for decades now. HN
| is not the place where you will find useful discussions on
| physics.
| choxi wrote:
| Are there better channels/forums?
| random314 wrote:
| Ask physics reddit might be better. But I have never
| engaged there.
|
| I am a physics novice too, but I am familiar with Electro
| magnetic field theory and special relativity. Any physics
| discussion on HN is bike shedding, if not outright wrong.
| Veritasium on YouTube is probably the best educational
| physics resource out there.
| vmoore wrote:
| One theory I have is that advanced intelligences are out there
| harvesting energy, so they deliberately start black holes to
| power their spacecraft. Imagine some sort of collection depot on
| the other side of a black hole that is harvesting exotic matter
| so they can travel vast distances with ease. </tinfoil>
| aaaronic wrote:
| I believe in Star Trek cannon, Romulans use artificial black
| holes as the power source in their ships.
| manmal wrote:
| The ,,three body problem" books develop an idea that is very
| similar to what you are suggesting.
| bdamm wrote:
| Perhaps space itself is the spacecraft, with extra-dimensional
| links between matter hiding in dark energy, creating an almost
| infinite capability for sensing and affecting matter? Perhaps
| black holes are the homes from which these aliens reflect their
| powers across the event horizon, providing powerful reach and
| safety? Or maybe they just live in the ocean and they don't
| like black holes either. I mean if we're going to go tin foil,
| might as well go all the way.
| Maursault wrote:
| What has always bothered me is the nomenclature; "black hole," is
| an astounding misnomer. A hole is not _something_ , it is a
| cavity in something else. Black holes are definitely _something_
| and a lot of it. Space is the black hole of the Universe, not
| black holes. Those are the mountains.
| yellsatclouds wrote:
| > _A hole is not something, it is a cavity in something else_
|
| this reasoning also applies to "infinity". it literally means
| NOT-finite. it refers to the lack of a thing: namely a biggest
| number.
|
| then again, freaking language and maths sure make us able to
| think about these 'lack of [blank]' as if they were actual
| things (to the point that _abstractly_ they are as real as it
| gets)
| Maursault wrote:
| > this reasoning also applies to "infinity"
|
| "Infinity" applies to the reasoning of what a hole is, but
| not to what a black hole is. A black hole is not _not
| something._ It is something, yet a hole is not something.
| Unlike a hole, a black hole is defined by its inherent
| characteristics, mass, spin and electric charge. A hole can
| only be defined by characteristics of what it is not, the
| empty volume of missing substrate.
| yellsatclouds wrote:
| agreed 100%. a black hole is a physical object unlike
| infinity. thanks for not letting me get away with being
| 'sublty wrong'.
|
| my larger point was about how language 'creates' such real
| abstractions; sometimes with terrible names (your original
| complaint).
| Maursault wrote:
| You are right about language, with contronyms and
| oxymorons. Especially in nomenclature, many things are
| named incorrectly or have contradictory names, such as
| Koala Bear, Whale Shark, Killer Whale, Starfish, Prairie
| Dog, King Cobra, Red Panda, Guinea Pig, Bearcat, Flying
| Lemur, Flying Squirrels, etc. Also, asteroid, which are
| not at all particularly "star like."
| Koshkin wrote:
| I think I've seen it spelled "black whole", but that's probably
| just me...
| klvino wrote:
| And I think we've seen the same Woody Allen movie
| random314 wrote:
| coldtea wrote:
| Well, it's not a description, it's a name. Names are allowed to
| not be accurate to the thing (a girl named Sandy is not
| necessarily made out of sand, and light is not light, it's
| weightless).
|
| And itself is based on two things: that they're absolutely
| black as in they don't reflect anything (that's what they
| believed when then the name came about), and that things can
| fall into them.
|
| > _A hole is not something, it is a cavity in something else_
|
| Well, and black holes can behave like cavities in the universe.
| They bend the surrounding area with their gravity so much that
| they end up forming a kind of cavity.
| Maursault wrote:
| But a black hole is not a cavity but instead the extreme
| opposite of a cavity.
| Nevermark wrote:
| "Black holes" absorbs light, so they can be reasonably
| thought of as "black" (despite lighting effects as it
| interacts with surrounding matter), and anything that gets
| too close falls in, like a "hole" (or a cavity).
|
| Compound names mostly come from associations, not careful
| logic.
|
| Names in general are arbitrary symbols, not definitions.
| Maursault wrote:
| My issue is not with the descriptor, "black," but in
| calling it a hole. You get too close to a star or planet,
| you will also fall in, but we don't consider stars or
| planets as holes. "Gravity well" is a better descriptor,
| but not when considered a hole, rather only when
| considered full of water, but here the water is instead
| gravity, and gravity always implies _something_ massive,
| not the absence of something else.
|
| Black holes, as we think of them as something, are really
| shadows. It'd be more accurate and less confusing to call
| them singularity shadows.
| Nevermark wrote:
| > "Gravity well" is a better descriptor, but not when
| considered a hole [...]
|
| But a well IS a hole in the ground and a pretty deep
| subject.
| Maursault wrote:
| > But a well IS a hole in the ground
|
| A water well is a special type of hole known as an
| excavation, meaning, of course, that it was excavated.
| Wells are not made by accumulating so many things that
| they just sink into the ground, and nothing is taken out
| of a black hole to create it.
| raattgift wrote:
| > You get too close to a star or planet, you will also
| fall in
|
| An object with a relatively much smaller mass can take a
| hyperbolic orbit arbitrarily close to a star or planet
| without "falling in". Practical examples include
| <https://en.wikipedia.org/wiki/List_of_hyperbolic_comets>
| and many small near-earth objects. Theoretical details in
| Newtonian gravity at
| <https://en.wikipedia.org/wiki/Hyperbolic_trajectory> and
| there is a literature exploring post-Newtonian
| corrections for such "orbits" (in e.g. General (or
| Numerical) Relativity, or formalisms like
| gravitoelectromagnetism or effective one body, for cases
| where one or both bodies are "compact" (like white dwarfs
| or neutron stars), the mass-ratio of the bodies is close
| to 1, or one or both bodies are moving at large fractions
| of c, or there is some combination of these features).
|
| An object can take a hyperbolic orbit arbitrarily close
| to a black hole without falling in.
|
| Black holes were first formalized in the context of
| General Relativity; commonly one would use a different
| term to describe something phenomenologically similar but
| set in a different theory ("fuzzballs", gravastars, and
| so on). Fevers and spots appear in diseases with very
| different causal agents (any number of quite different
| bacteria, viruses, and other things may cause grossly
| similar symptoms in the victim). Likewise, _apparent
| trapping surfaces_ can appear in many ways in different
| theories of gravitation or in different configurations of
| variables within a single theory of gravitation.
|
| The important word in the previous sentence is
| "trapping": anything crossing that surface from the
| outside to the inside cannot cross back to the outside
| for arbitrarily long times. Differences in configurations
| on the inside of a trapping surface do not materially
| affect the outside _at all_. The "apparent" qualifier
| captures the possibility that the trapping surface does
| not go to the eternal future because of (for example)
| instabilities from quantum effects (Hawking-style), so we
| can take _at all_ as meaning "for a very very very very
| verrrrrrrrry long time".
|
| The observables of a black hole in General Relativity (in
| its form as a physical theory that adequately represents
| many physical features of our universe) are all outside
| the event horizon. Anything inside the horizon stays
| permanently inside. From the outside one cannot test the
| internal configuration. While the internal configuration
| is described in several black hole solutions to the
| Einstein Field Equations, nobody expects that just
| because the _external_ configuration (outside the black
| hole) is a good physical model, that therefore the
| _internal_ configuration must be a good physical model
| too. Roy Kerr makes this point almost every time he
| lectures about his solution for black holes with nonzero
| angular momentum (example: 48m04s mark
| <https://youtu.be/nypav68tq8Q?t=2884>, where he points
| out that the Kerr solution is a _vacuum_ solution, and
| that adding matter inside the horizons is likely to
| dramatically change the black hole internal
| configuration. Note however that adding matter to the
| _outside_ part of the Kerr solution is highly likely to
| be undramatic, and that is one reason why the Kerr
| solution is astrophysically useful).
|
| Stars and planets differ from black holes in that there
| is no apparent trapping surface. You can shoot an
| electron neutrino right through the Earth or the Sun. You
| can't shoot an electron neutrino through a black hole: if
| it goes in, it stays trapped inside.
|
| Your term "singularity shadows" presupposes that as we
| develop better solutions (numerical or analytical) of the
| Einstein Field Equations for (apparent) astrophysical
| black holes, the singularities that appear in e.g. the
| Schwarzschild or Kerr solutions will remain. That may not
| be true. I don't think the "shadow" part adds any
| accuracy.
|
| It is not true that "gravity always implies matter". In
| General Relativity there exist several exact solutions to
| the Einstein Field Equations where there is significant
| spacetime curvature but no mass. Some of these usefully
| approximate features of the universe we observe, even
| though as far as we can tell there is no part of our
| universe that is completely free of matter (in the most
| general sense, including electromagnetic radiation),
| although large and growing regions are so sparse that the
| matter in them does not collapse gravitationally into
| clumps. This trend is just as much an effect of spacetime
| curvature as is the gravitational collapse of dust clouds
| into stars.
|
| Finally, you can use whatever nomenclature makes you
| happy. It's just a fanciful term that covers a wide range
| of theoretical descriptions and astrophysical phenomena.
| Astrophysicists and theorists use "black hole" knowing
| that they may be talking about quantitatively and
| qualitatively different objects with fairly similar
| symptoms being presented. But they also know how to find,
| read, and understand a precise mathematical description
| that removes the ambiguities of English (and other
| languages) and any inaccuracies (in some settings a black
| hole may be a very weak greybody radiator; and in some
| settings "hole" may be less poetic and more descriptive,
| e.g. in Wheeler's bag-of-gold solution). Substituting
| some other pithy name for "black hole" doesn't help these
| physicists, and is unlikely to help anyone who doesn't
| know how to deal with the formal, unambiguous
| descriptions of them.
| Maursault wrote:
| > An object with a relatively much smaller mass can take
| a hyperbolic orbit arbitrarily close to a star or planet
| without "falling in".
|
| The same is true of a black hole. 90% of the matter
| orbiting a black hole will never fall into it.
| raattgift wrote:
| > The same is true of a black hole.
|
| Yes, as I wrote in the second paragraph:
|
| >> An object can take a hyperbolic orbit arbitrarily
| close to a black hole without falling in.
|
| It occurs to me that in your various comments here you
| are thinking of the point mass (or divergence of the
| Kretschmann scalar or whatever) as the black hole.
| Conventionally, and for good practical reasons,
| practically everyone working with astrophysical and
| theoretical black holes define the _horizon_ as the black
| hole.
|
| It's frequently tempting to think of the point-mass in
| Schwarzschild as the _generator_ of the event horizon.
| After all, it 's usually described as being a surface at
| r = 2GM/c^2, with "M" doing the heavy lifting, if you'll
| pardon the expression. However, Schwarzschild is an
| _eternal_ black hole, rather than one that forms by
| gravitational collapse. For the case where there is some
| matter and no black hole - > some matter + a black hole,
| it is the early configuration of the "some matter" that
| generates the event horizon.
|
| If one, following Lemaitre-Tolman <https://en.wikipedia.o
| rg/wiki/Lema%C3%AEtre%E2%80%93Tolman_m...>, takes a
| spherical shell of radiation with a total momentum-energy
| comparable to a galaxy all moving radially inwards, and
| starts the spherical shell at billions of light-years
| from the shell's centre, then anything already at the
| centre (even a small interplanetary civilization) is
| already inside the event horizon before the
| civilization's home planet formed. Barring faster-than-
| light travel, nothing within (or produced by) the
| "victim" solar system will be able to cross outside a
| surface near the trailling edge of the inrushing
| radiation: at early times all possible low-speed
| trajectories from the victim solar system ultimately
| recurve back to a (set of) point(s) within it and at late
| times all possible high-speed trajectories recurve
| inwards.
|
| Near the latest time in the collapse, everyone outside
| the victim solar system can conclude the victims are
| inside a black hole, even though for hours to days (and
| much longer, if we make the total mass of the shell
| extremely large) the victims inside will still be going
| about their business wholly unaware (because "c") of
| their fate. Horizon = yes. Singularity = no ("not yet",
| perhaps).
|
| Finally,
|
| > 90% of the matter orbiting a black hole will never fall
| into it.
|
| is probably wrong, especially if one takes "never"
| literally. The dynamical spacetime in the near horizon
| region is on its own probably enough for orbital decay of
| anything in close orbit (a few tens of R_{crit} ~
| R_{Schwarz.}) and there are plenty of forcing functions
| on bodies in elliptical orbits at greater remove,
| particularly in galaxy cenrtres and globular clusters.
| goatlover wrote:
| It's a hole in spacetime in the sense that the inside of
| the Black Hole is completely cutoff from the outside,
| with the exception of Hawking radiation. A black hole's
| interior is causally separate from the rest of the
| universe.
| zethus wrote:
| The author does take a wild ride into the world where,
| via Hawking radiation, the interior is NOT causally
| separate, yet quantum-ly entangled.
| Maursault wrote:
| This doesn't solve the problem. Spacetime itself is a
| hole, so you're saying a black hole is a hole within a
| hole, and we can designate an infinite number of holes
| within a hole.
| forgotpwd16 wrote:
| Sounds like something you'll read about in modern
| physics.
| thaumasiotes wrote:
| > a girl named Sandy is not necessarily made out of sand
|
| Technically, the meaning of the name is "defender of men".
| [deleted]
| forgotpwd16 wrote:
| >A hole is not something, it is a cavity in something else.
|
| You can say black holes are holes in spacetime with a big rock
| at the bottom.
| Maursault wrote:
| > You can say black holes are holes in spacetime with a big
| rock at the bottom.
|
| The more I've thought about this, the more it seems wrong.
| Black holes are not a hole in spacetime like a puncture hole
| in fabric. There is no missing spacetime like there would be
| missing fabric. Black holes are more accurately a round 4D
| valley in spacetime rather than a hole in spacetime.
| forgotpwd16 wrote:
| >Black holes are not a hole in spacetime like a puncture
| hole in fabric.
|
| Who said puncture holes? Ground holes also exist you know.
| Maursault wrote:
| All holes are punctures, including ground holes.
| thaumasiotes wrote:
| There are no holes that puncture the ground. All holes in
| the ground are, in your terminology, "valleys".
| Maursault wrote:
| A puncture _is_ a hole, and vice versa. These are
| synonyms.
| forgotpwd16 wrote:
| Not really, unless you can find a contrasting definition
| to one found on WorldReference. Puncture is defined as
| making a hole in surface (the boundary) rather a volume
| (the solid). In any case this goes off topic. You've
| apparently misunderstood what people usually mean with
| hole. (edit: Or maybe I've. Now I'm confused. Here goes
| the rest of my day thinking about the meaning of holes.)
| yamtaddle wrote:
| - "Black" -- self-explanatory.
|
| - "Hole" -- things fall in and don't come out (more or less).
|
| Plus they look like holes on those 2d representations of space-
| time.
|
| Seems reasonable to me.
| Maursault wrote:
| > - "Black" -- self-explanatory.
|
| I wasn't willing to argue this before because my issue was
| not with the adjective. But actually black holes are not
| really black, they emit radiation.
|
| > - "Hole" -- things fall in and don't come out (more or
| less).
|
| But things fall into any massive object like planets or
| stars, so "hole" is ambiguous. Things also fall out of holes,
| such as holes in a ceiling or screw holes.
|
| > Plus they look like holes on those 2d representations of
| space-time. Seems reasonable to me.
|
| It is a fair point to say that the hole of a black hole is a
| 4 dimensional hole, except that space-time is itself a 4
| dimensional hole, leading to more ambiguity.
| codethief wrote:
| > except that space-time is itself a 4 dimensional hole,
| leading to more ambiguity.
|
| You keep repeating that spacetime were a hole. What makes
| you think that?
| Maursault wrote:
| Holes are made of space by definition, therefore
| spacetime is a hole.
| nahstra wrote:
| What definition?
|
| Definitely not true in math - if you take a circle (S^1 =
| { (x, y) : x^2 + y^2 == 1 }) it has a hole as defined by
| homotopy in the middle and there is no 'space' there. If
| you fill it with space you get a disk (D^2 = { (x, y) :
| x^2 + y^2 <= 1 }) there is no longer a hole as defined by
| homotopy/is contractible.
| klvino wrote:
| If something were to "fall" into a "Black Hole", from the
| object's perspective, the object would seem to "fall" for an
| infinite amount of time.
| bobbylarrybobby wrote:
| If you dig a hole and toss something in you don't really
| consider the thing part of the hole (it's _in_ the hole, but
| it is not the hole) but with the "black hole" the meaning of
| "hole" is "the volume enclosed by the event horizon _plus_
| all the stuff inside it ".
| [deleted]
| dlandis wrote:
| Curious how you feel about donut holes.
| quercusa wrote:
| _The implication is that, in some strange sense, the outside of a
| black hole was the same as the inside, like a Klein bottle that
| has only one side._
|
| The moment Cliff Stoll has been preparing for!
| Blammar wrote:
| (For those that don't get the reference:
| https://www.kleinbottle.com/ )
| rfreytag wrote:
| https://web.archive.org/web/20221010171135/https://www.nytim...
| aortega wrote:
| cleansingfire wrote:
| Nice job describing why ER=EPR is so exciting, and conveying
| conflicts within physics. The idea that Einstein held conflicting
| views is important to keep in mind because we see him being led
| by the data rather than dogma. Susskind has a lot of interesting
| ideas and excels at sharing his excitement. These are interesting
| problems and quantum physics has great difficulty communicating
| well, and still has plenty of nonsense sadly. Yes, Einstein was
| conflicted, sans acknowledged these things. Susskind used to be a
| string theorist. People grow and learn.
| bilsbie wrote:
| So what's the secret?
| dang wrote:
| Who knows. I've replaced the baity title* with representative
| language from the article body. No doubt someone else can do
| better, and we'd be happy to change it again.
|
| * " _Please use the original title, unless it is misleading or
| linkbait_ " - https://news.ycombinator.com/newsguidelines.html
| plutonorm wrote:
| The article was written by GPT-3
| zethus wrote:
| fall into a black hole and find out :)
| pelagicAustral wrote:
| I have, it's called js.
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