Do black holes exist? The world’s most famous scientist vs. the actual science.

“My goal is simple. It is a complete understanding of the Universe, why it is as it is and why it exists at all.” -Stephen Hawking

Here in our little corner of the Universe, the Earth is a pretty intense source of gravity for us. If we want to escape its gravitational pull, we’d need to accelerate ourselves up past the escape velocity, or the speed necessary to climb out of the gravitational potential well that Earth’s mass creates. We can (and have) accomplished this, in fact, but it would take a speed of around 11.2 km/s (or 0.004% the speed of light) to make it so.

Image credit: NASA / Apollo 17; modifications by Wikimedia Commons user Ultimate Roadgeek.

Image credit: NASA / Apollo 17; modifications by Wikimedia Commons user Ultimate Roadgeek.

But that’s not so fast, after all, not compared to a great many things in this Universe. The reason that we don’t need higher speeds to escape from our planet is that despite having a decent amount of mass — some 6 × 10^24 kg, or some 10^49 heavy atoms — our Earth is spread out over a relatively large volume of space.

But if the laws of physics were somewhat different, we might be able to compress the mass of our Earth down into a much smaller region of space. And if we could, it would take greater and greater speeds to escape from it. At some point, when all the mass of the Earth was compressed into a sphere a little smaller than a centimeter in radius, you’d suddenly discover that nothing in this Universe — not even light — could escape from it.

You’d have turned the Earth into a black hole.

[Go read the whole thing -- in which the firewall paradox is resolved -- at Starts With A Bang on Medium. Yes, I brought it up as a possibility yesterday; let's try it and see if you respond!]


  1. #1 Darren Lovelace
    Monmouth Oregon USA
    February 1, 2014

    I believe the Hawking Susskind Paradox has fully released the genie from the bottle. It would be good to hear from one who has an understanding of such paradox and the methods in which they are resolved. Well done Ethan.

  2. #2 Ld Elon
    February 1, 2014

    I agree upon the information loss/ liberated, the outer two would instantly bond within the edge/skin of the darkredsuns ‘horizon.

    They would also bond each others information and have more weight. so no info is really lost, because of the instant connection of the escapees.

    Plus, by being able to see emissions, one would be able to discover exactly what colour the darksun is… obviously its darklight colour, ;0

  3. #3 Sinisa Lazarek
    February 1, 2014

    @Ld Elon

    if only you had a clue about how clueless you are

  4. #4 Michael Kelsey
    SLAC National Accelerator Laboratory
    February 1, 2014

    @Ethan — I hope you are reading the comments on this side of the firewall :-) I don’t get how Hossenfelder’s solution (particle exchange symmetry eliminating the Hawking-radiation entanglement) resolves the underlying problem of “information loss” (non-unitary evolution).

    Real, astrophysical black holes accrete. There’s information content in the matter that gets accreted (not to mention the original matter which collapsed), beyond the information present in the (previous version of) entangled Hawking pairs. When a real, astrophysical BH eventually evaporates, that additional information is also lost, isn’t it?

    Or is the dependence of Hawking radiation on the BH mass such that it is already decohering that additional information, making the whole thing a nice non-pure density matrix?

  5. #5 Ethan
    February 2, 2014

    Michael, this “firewall” preserves unitarity, so I can see your posts.

    Her paper is not designed to remove the information loss problem; that is a separate problem with a separate (accepted, I believe) resolution. But it does resolve the non-unitary problem that results in the creation of a firewall.

    I asked Sabine about this directly, and here is what she said:

    Normally entangled pairs of particles are produced in the vicinity of the black hole horizon. One of the pair falls in and vanishes, the other one goes out and contributes to the Hawking radiation. Problem is, you never get to see the one that falls in (that’s the part that is traced out from the density matrix), so you lose information in that process (it is no longer unitary).

    What I found that needs to happen instead (and that’s also what the Verlinde & Verlinde swap does) is the following. Take two pairs (same momentum) and swap the entanglement from in-out in-out (the normal case) to in-in, out-out (which I call ‘disentangled’). You still have two entangled pairs, but now its a pair outside and a pair inside instead of two pairs that are entangled across the horizon. ‘Disentangled’ here does not actually mean the state has no entanglement, but it has no entanglement across the horizon.

    I hope this helps!

  6. #6 Michael Kelsey
    SLAC National Accelerator Laboratory
    February 2, 2014

    Thanks, Ethan! Yes, it does help. I’ll have to look up the papers (no, I’m *not* going to ask you to do it for me :-) on the “accepted resolution” of the inforrmation-loss-due-to-infalling-stuff that I raised. I’m not an astrophysicist, so I don’t have all this stuff in my head.

  7. #7 G
    February 2, 2014

    If the influence of entanglement is instantaneous, then its velocity if infinite, and it can escape a black hole. In that case, an in/out pair solves for the issue of information transfer without breaking any rules, as follows:

    Consider an entanglement experiment to be analogous to a one-time-pad encryption system. Alice manipulates a polarizer to correspond to a series of bits that represent a text. Bob receives a string of polarized photons. But he can’t tell which photons were and which were not, the outcome of Alice’s manipulation. However if Alice supplies him with information from her side of the experiment (transmitted at c or below), he can now “decrypt” his bit string (ciphertext) and recover the original bit string (cleartext).

    The information encoded into the bit stream by Alice was always “implicate” in the bit stream received by Bob, but was inaccessible to him until he received the “key” from Alice.

    In the same way, information from within the event horizon is implicate in the behavior of the “out” particles of entangled pairs, but remains inaccessible to us because we don’t have the “key” in the form of the behavior of the “in” particles. This neatly straddles the issue of information transfer from “inside” to “outside.” That or I’ve missed something obvious and done a laughable foot-in-mouth maneuver.

    Ethan, I don’t see the comments section on Medium but it may be my security software is blocking it. One time when I checked, I saw something to the effect that a social media login was required.

    If that’s the case, then you’ll lose me and anyone else whose job requirements entail security measures that don’t allow the use of social media, with its relentless tracking malware and information promiscuity. If you want us all to go away, feel free to exit Otherwise, despite the frequent appearance of nonsense in these comments, it would be worthwhile to stick around.

  8. #8 Sinisa Lazarek
    February 3, 2014

    @ Ethan

    can you clarify this bit to us laymen

    “Take two pairs (same momentum) and swap the entanglement from in-out in-out (the normal case) to in-in, out-out (which I call ‘disentangled’). You still have two entangled pairs, but now its a pair outside and a pair inside instead of two pairs that are entangled across the horizon. ‘Disentangled’ here does not actually mean the state has no entanglement, but it has no entanglement across the horizon.”

    How does a virtual pair production outside of BH (out-out) have any relation to BH itself in terms of hawking radiation, or in-in? I thought original premise took into account those types as well, but they didn’t contribute anything. So how is this now the correct solution, and how does this help?

  9. #9 John Duffield
    February 3, 2014

    I read the full article* Ethan. I think there’s more that’s wrong with all this stuff than people appreciate. Ever read about Friedwardt Winterburg’s firewall? He’s been rather cold-shouldered and ignored, because competitors are better at PR. But I think his firewall is the one that’s right. And that black holes exist, but Hawking radiation doesn’t. Heresy!

    * IMHO the poor provision for comments is off-putting. I know they can be a pain, but they bring a blog to life.

  10. #10 Wow
    February 3, 2014

    “He’s been rather cold-shouldered and ignored, because competitors are better at PR”

    Was that merely PR trying to make out that he was not cold shouldered because he couldn’t back up his claims with evidence?

  11. #11 Ethan
    February 3, 2014


    Fully “out-out” or “in-in” pairs will re-annihilate in short order, returning to the quantum vacuum with no net radiation. (I struggle a little to explain this in QM terms and not in the full QFT terms, but let me try to bridge the gap.)

    However, keep in mind that the radiation — at these energies — will be far less than the mass of a particle, so we need a virtual matter and antimatter particle to annihilate outside of the event horizon, which means you need two pairs.

    On its own, this will contain no black hole information (other than Temperature), but you can get the proper radiation emanating from a location very close to but outside the true event horizon, and no firewall. The information part is far too esoteric for a blog comment.

  12. #12 John Duffield
    February 3, 2014

    No. See Woit’s blog where Friedwardt said this:

    “The conclusion that a black hole is at the event horizon surrounded with a wall of fire by the disintegration of infalling matter was first proposed in an article I had published in 2001 in Zeitschrift fuer Naturforschung 56a, 889 (2001). My paper had the title “Gamma Ray Bursters and Lorentzian Relativity”. It is Lorentzian relativity which resolves the black hole information paradox, with no information loss or violation of unitarity. In Lorentzian relativity SRT and GRT remain extremely good approximations for energies small compared to the Planck energy. My paper is cited in “An Apologia for Firewalls” by Almheiri, Marolf, Polchinski, Stanford and Sully: arXiv:1304.6483v2 [hep-th] 21 jun 2013.

  13. #13 Sinisa Lazarek
    February 3, 2014

    @ Ethan

    will have to dig a bit deeper to understand, need to read those papers again. But something else just struck me as odd. If we are now looking at out-out pair which is entangled between themselves, for it to somehow have any information about the black hole, isn’t it suppose to be entangled with BH also, to some degree? I’m sure this is somehow wrong since as far as I know (maybe wrong), can’t have entanglement between 3 things.. or can you?

  14. #14 Sinisa Lazarek
    February 3, 2014

    .. or is that the esoteric part? :)

  15. #15 Wow
    February 4, 2014

    I think the out-out pair are carrying information that never got inside the black hole, whilst the in-in pair are carrying information that did get inside the black hole.

    A horrible way of putting it, I know.

    But a pair that stands athwart the event horizon will have some information inside and some outside, same for the other pair. When the outer two decide to meet up, letting the inner two go, no information crosses the line, but each of these pairs then “mixes up” information, so the original information of the two pairs isn’t escaping, the result of the admixture, which was never inside, does.

  16. […] Yes, Virginia, Black Holes Exist! (A synopsis) – Starts With A Bang […]

  17. #17 Gary S
    February 10, 2014

    Maybe black holes exist, but we could never know for sure… Wouldn’t the relativistic time retardation at the event horizon appear to slow down the infalling matter, so that from an outside point of view, the event horizon would take an infinite length of time to form? For practical purposes then we could never detect a black hole!

  18. #18 PJ
    February 10, 2014

    Compared to its surroundings, the ‘hole’ would become obvious due to a lack of light emanating from it. But then, that would assume the hole were funnel shaped. Since the BH is contrived to act in the way of a vortex where matter moves toward the centre of that vortex, toward the event horizon, then over the edge into oblivion. Of course, this would be happening from both sides of the galaxy containing the BH.
    If, however, the hole is spherical in nature, it would never be detected (visually) since it would be surrounded by matter being drawn into it.

  19. #19 Sinisa Lazarek
    February 11, 2014

    @ Gary S

    yes, from p.o.v. of a far observer, it will seem like it takes forever for anything to cross event horizon.

    As for detection, no. It’s about not detecting it by EM detection, but by gravitational. Or in case of active ones there are jets and so on, which are visible so we can talk about EM.

    From theoretical standpoint, you will never ever be able to detect the singularity visually from some distance outside. And if looking at relativistic time, that matter and light that never seems to reach event horizon, it’s wavelenght is so redshifted that it’s black for all intent.

    But again, it’s not the issue of not being able to see it, it’s enough to be able to feel it. If stars orbit so fast around something that you can’t perceive… and GR tells you it’s mass based on orbital velocities seems to be i.e 800 solar masses…. call it what you will.. I call it black hole.

  20. #20 Sinisa Lazarek
    February 11, 2014

    @ PJ

    you have a wrong mental image of BH. There is no funnel, or center of vortex or over the edge oblivion. It’s a sphere, like anything else out there. i.e. a neutron star but much denser.

    The “funnel” etc is what you see when fields and spacetime trajectories are plotted mathematically in coordinate systems. It’s not a “physical” representation of the object itself.

  21. #21 Wow
    February 11, 2014

    “As for detection, no. It’s about not detecting it by EM detection, but by gravitation.”

    Indeed, that’s how supermassive stars are detected: how much mass in the volume, and could it be explained by a large number of small stars?

    With black holes, you have the advantage that they’re not radiating themselves and the accretion disk will have an over-abundance of X rays. So to an extent, they’re easier to spot than supermassive stars.

    My first year end-of-year essay was on supermassive objects, which I figured everyone else would think means “supermassive black holes”, therefore if I were to follow suit, I’d be competing with others choosing the subject. But heard of evidence (still entirely at that time controversial) of stars bigger than the supposed limit of ~60So Mass.

    Unfortunately for me, the prof given the essay thought such stars were a load of impossible tosh, and was interested in black holes (who got what paper was predetermined on subject but not mentioned to us), so I got a poor mark. If it had gone to a different prof, who was one of the ones thinking the evidence solid enough to be believable, I may have gotten a much better mark.

    Bummer, eh?

  22. #22 Sinisa Lazarek
    February 11, 2014

    “Unfortunately for me, the prof given the essay thought such stars were a load of impossible tosh”

    I learned on my own skin how schools kill any creativity in students. In elementary school, as well as in highschool.

    I won’t say all of them, of course. Lucky are the ones who had faculty that was supporting and informative. Chemistry, physics, math, IT, biology… all the fields I adored as young, were the subjects I came to hate while in school, only because of the professors.

  23. #23 Wow
    February 11, 2014

    I learned on my own skin how schools kill any creativity in students.

    I won’t say all of them, of course.

    Well, that’s either because you knew the first statement was hyperbole, or you’re scared to say what you really think.

    Bad people will kill any creativity they come across.

    Parent, guardian, friends, newsreporters, blogwriters, teachers, politicians, priests or maniacs in an asylum.

    Bad examples of those, wherever they reside, will kill creativity.

  24. #24 Sinisa Lazarek
    February 11, 2014

    I wouldn’t say they were bad people… just uninterested in student engagement. Bad as teachers and pedagogues, but not as persons.

    i.e. in 6th grade I was suppose to present an experiment at city’s chemistry science fair, I didn’t because chemistry teacher told me she didn’t have time for extracuricular activities. In high-school couldn’t learn anything in math classes cause it was total chaos in class (math professor didn’t really had any sense of authority so it looked more like recess than math), physics professor gave anyone involved in IT a “c”, because IT department got his old physics laboratory. He considered something like that outragous. And finally in IT… in 2nd year of high-school once we started doing turbo pascal, asked a professor how to write a code that won’t stop if a user pressed ctrl+break.. and got a flat face response and couple of blinks, then admited she hadn’t had a clue how to that.

    So after those days, had to rely on myself to get the info I needed. But still feel bad about school days… could have done so much more if someone was actually interested in teaching.

  25. #25 Sinisa Lazarek
    February 11, 2014

    p.s. people (myself included) tend to forget what information was like before internet. I couldn’t google or visit wikipedia. Any info I had came from teachers and professors… so when they didn’t seem to care to teach you something more outside of textbook.. it sucked… big time.

  26. #26 Sinisa Lazarek
    February 11, 2014

    … but anyways.. none of that has to do with black holes :) so..

  27. #27 Wow
    February 11, 2014

    I wouldn’t say they were bad people… just uninterested in student engagement.

    Disinterest would have them merely NOT engage with creativity. Not quash it. That takes effort. And if you’re disinterested, that’s not going to happen.

    I’m using bad in the sense that these people who want to quash creativity are doing something bad with deliberate intent to bring about the result: conformity and suppression of creative thought.

    That can hardly be called good.

    Nor neutral.

    So “bad” is all there is left.

    And it isn’t the institution doing this. A bad teacher will be a bad teacher whatever school they’re in, or none at all.

    But it isn’t just teachers.

    Politicians, police, employers and so on will all do this if they are of the same intent.

    See Hannity. See Phelps. See Inholfe or Abbot.

    But would you get away (or even *try*) to claim that TV quashes creativity? That religion quashes creativity? That politics quashes creativity?


    But you’ll do it for schooling.

    Hardly fair minded, is it.

    It’s not the place, but the person. And power given to them to enact their desires over others.

    School is just one place where some people are given power over others, but in your life, a very small place.

  28. #28 Wow
    February 11, 2014

    i.e. in 6th grade I was suppose to present an experiment at city’s chemistry science fair, I didn’t because chemistry teacher told me she didn’t have time for extracuricular activities.

    Maybe she didn’t have time.

    School sizes have increased a hell of a lot, and more homework means more homework to mark, but politicians see “give kids more homework” as a simple *measureable* act that “looks” like it should work.

    Because raising taxes won’t work in poor neighbourhoods (they have no money spare), and won’t be accepted in good neighbourhoods (they don’t want to “pay for other kids’ learning”), and raising general taxes will lose votes because the US social construct and mythology is as broken as the Old English Empire was.

    So maybe they didn’t have time.

    It isn’t quashing creativity.

  29. #29 Sinisa Lazarek
    February 11, 2014

    “So maybe they didn’t have time.

    It isn’t quashing creativity.”

    agree.. that yes.. she had her own reasons. That’s why I said I don’t considered them bad. It wasn’t anything against just me.

    As for creativity… depends. Maybe I used the term too broadly. It’s didn’t quash ability to think creatively, but it certainly quashed my interest and love for chemistry. Since without teacher support, no access to lab or any extra study.

  30. #30 Wow
    February 11, 2014

    “agree.. that yes.. she had her own reasons. That’s why I said I don’t considered them bad.”

    So it was the school she was in that made her quash your creativity???

    Or was it as I stated earlier: you knew the first statement was hyperbole.

    a) don’t demonise a group because it makes a catchier soundbite
    b) don’t give someone an out just because you can punish a group with more impunity and better “community support”

    Whoever quashed creativity did it. Not the place they worked. And most of those who will do so will do it elsewhere (more jobs are not as a schoolteacher), and you will spend longer with them (your working life is longer than your school years).

    But I guess we’re just not going to see what the other one is trying to do here because you don’t really mind blaming schools as if they all crush creativity. It “feels right” to you and feels heinous to me.

  31. #31 PJ
    February 11, 2014

    Thanks, Sinisa, for your clarification @20. If you read further in @18, para 2, I did mention the possibility of the spherical nature of BHs. It seems the media tends to portray BH as a type of funnel affair where matter is drawn in over the ‘event horizon’ and then down the tunnel. Very misleading.

    As for education, it is there to give you the tools to find out what you want to know in life. If you do not have the desire or conviction for creativity, you cannot blame anyone else for ‘quashing’ that potential. It is your life and your choices that put you where you are today.
    I cannot blame my teachers for my path in life. I chose that direction, and I thank them for their lessons.

    So, lets get back to the original topic.

  32. #32 Michael Kelsey
    SLAC National Acclerator Laboratory
    February 11, 2014

    @PJ #31: The media portrayal of black holes as funnels is endemic, and the clear result of copy-and-copy-and-copy (like textbooks, only worse :-). The same visual imagery is used even in undergraduate physics textbooks, however.

    The reason is relatively simple. How do you present an effectively four dimensional space (i.e., embedding the true three-dimensional curved space in a 4D “frame”)?

    The answer is, you can’t, not in a way that a non-expert could hope to understand. So instead, we reduce the true 3D curved space to a 2D analogue (the “rubber sheet model”), and show the curvature of that in a 3D “frame” (technically, an “embedding space”).

    There’s a nice physical version of this which you’ll find at many science museums.

    It’s a hyperbolic funnel, six or seven feet in diameter, with a groove around the top where you can shoot marbles. Friction slows the marbles down, and they go into looping, elliptical orbits around the hole in the center, eventually getting trapped and falling through to the bottom where you can collect them.

  33. #33 PJ
    February 11, 2014

    Thankyou Michael, much appreciated.
    A pity my formal schooling finished in the early ’60s. Not much interest shown by science teachers re astronomy & allied fields in those days.
    Still, didn’t stop me from building telescopes. Rather enjoy the visual side of the interest.

  34. #34 unknown
    February 19, 2014

    Will the sun explode?

    Yes or No?

    ( o.o)

  35. #35 Wow
    February 20, 2014

    Wrong thread.

  36. #36 Jackelyn Meuler
    April 18, 2014

    I like your blog, Its nice to start to see not all people is just posting a heap of garbage these days!

  37. #37 Ida Glover 14013984
    South Africa
    April 20, 2014

    “Albert Einstein thought that a black hole- a collapsed star so dense that not even light could escape from it- was too preposterous to be real. Einstein was wrong”- Michael Finkel

    Something is out there, at least in an mathematical sense. Black holes can not be seen but their location can be plotted by measuring their effect on the orbits of the surrounding stars. Whole stars that get to close are pulled in, torn apart and devoured.
    If Earth, like you said, could compress its mass down and collapsed in an black hole, the size would be around 7 inches and it would weigh the same as it does today.

    The black hole at the centre of our universe is 4.3 million times as heavy as our sun, it is called Sagittarius A*.

    To comment on the 34th post about the question if our sun is going to explode- no. Our sun is small and its death will be quiet. When our sun used up all of its hydrogen fuel in about 5 billion years, its outer layers will drift away and the core will become what is known as a white dwarf.