Challenging the nature of black holes


The nature of black holes has puzzled physicists for decades. But while the debate has fizzled in recent years, some new thinking is about to set it alight again.

Black holes are fundamentally a product of general relativity, which allows for a gravitational collapse so violent that no other force can oppose it. When that happens, the collapse continues until the density of matter becomes infinite and gravity becomes so strong so as to prevent even light from escaping. This generates an “event horizon”, a volume of space around the black in hole inside whihc events cannot affect an outside observer.

But perhaps there’s more to it than that, suggest Matt Visser at Victoria University of Wellington in New Zealand and pals who ask whether quantum processes can have an affect on the collapse of a star.

It’s fair to say that the consensus among astrophysicists is that quantum physics can be safely ignored when considering the collapse of a star. As Visser and co put it: “There is a widespread feeling in the general relativity community that semiclassical quantum back-reaction effects are always small, and never enough to significantly alter the classical picture of collapse to a black hole.”

But Visser and pals beg to differ. The standard thinking is that if an event horizon forms, then quantum field theory is well behaved there. But that makes the assumption that am event horizon will form.

Visser and co say this may not be a valid assumption and go on to show how the vacuum energy might stifle the formation of an event horizon.

What does this mean for black holes? What Visser and co end up with is something very similar to a black hole but without an event horizon–a black hole mimic, they say.

Debating the nature of black holes is a well trodden path. But what’s interesting is that numerous avenues of thought–from loop quantum gravity to abstract studies of the nature of horizons–are now hinting at something more subtle and interesting about the nature of star collapse.

Black holes might never be the same again.

Ref: Small, dark, and heavy: But is it a black hole?

7 Responses to “Challenging the nature of black holes”

  1. Zephir says:

    The question of event horizon is pretty complex. From AWT follows, only medium sized BH can have an event horizon, the larger ones would appear like shinning quasars (a naked singularities).

    If we could travel into medium sized BH (bellow 4 mil Sun masses), the event horizon should be apparent from distance by gravitational lensing. If we would approach more close into it, it would open and expand over whole horizon and at the certain moment it would appear behind our back. It means, the former universe would appear like the original black hole and vice-versa. During this the inhomogeneities of event horizon would collapse into black holes and gallaxies sitting on the surface of newly created universe. But this is just a very rough view.

    Under more detailed view we could see an event horizon surrounded by dense ring of dark matter. Beneath this event horizon an even more complex structures of giant bubbles would appear, simmilar to foamy structure of dark matter, the density of which would gradually increase, until it would condense into qauntum foam, forming the vacuum foam inside of black hole.

    But we could never see this beauty in its entirety, because we would evaporate into accretion radiation a well before we could ever approach an event horizon. Which makes this description a somewhat abstract thing, testable only by dispersion of gravitational waves and/or neutrinos at distance.

  2. Zephir says:

    The question, why heavy BH have no event horizon can be explained in plural ways. In general, sufficient distance is required for the manifestation of vacuum density gradient as a event horizon, where total reflection phenomena can manifest itself. From sufficient distance every density gradient becomes sufficiently sharp to reflect most of energy from BH back into BH. For very heavy BH such distance is too large to fit into observable Universe scope, so we can see huge black hole as a shinning quasars.

    Event horizon of smaller black holes is less or more closed due the insintric BH rotation, so that only polar jets can leave the gravitational field as an exagerated case of gravitational brigthening, which is observable even for another giant rotaing stars. Part of energy emanated by these jets condenses into giant fountain, which generates the flat shape of medium aged gallaxies, rest of energy escapes in form of antimatter clouds of dark matter, surrounding the gallaxy and central black hole.

  3. Zephir says:

    Classical Schwartzchild’s geometry of relativity is rather rough model of BH, because it is a steady-state model, which doesn’t care about dynamics of BH formation in more general reference frame. In general, black hole cannot have central singularity, if they’re not older then the age of the observable Universe – the matter inside would simply have no sufficient time to collapse into singularity, because the speed of energy spreading slows down with matter density.

    Another conceptual problem is, the gravity field inside of heavy object is always flat, which violates the central singularity model. As the result, the singularities can exist inside of black holes only in form of many daughter black holes, which are forming the gallaxies around them by the same way, like gallaxies inside of our Universe generation. Density gradient of black hole is rotating and undulating due the quantum gravity phenomena, which are manifesting itself by simmilar way, like surface tension of water droplets and nested density fluctuations formed inside of condensing supercritical fluids and boson condensates.

  4. lucas says:

    Sorry, but I really must state that the above three comments have no generally accepted backing in the physics community, especially the notion of aether wave theory. Zephir, please refrain from putting forth theories that lack peer review.

  5. Zephir says:

    How peer-review and publishing activity are related mutually? These two things have nothing to do each other. You can publish theory in one media and to review it in another a few years later without any problem.

    After all, peer review doesn’t prohibit people in publishing aparently contradicting theories: some of them are promoting hidden dimensions, some other are denying them – how is it possible, both theories passed peer review?

    This may be good for members of scientific community, which needs some inter-subjective criterion of their salary – but I’m not payed from public taxes by any way.

    If such dangerous & expensive project like LHC can be started without peer reviewed security analysis, why not to present harmless ideas in anonymous discussions? Double standards of criticism are sign of pseudoskepticism.

    At the very end, arXiv blog is dedicated just to ideas and articles, which weren’t passed by peer review yet. You’re crying on wrong site apparently.

  6. Zephir says:

    The case of AWT is somewhat paradoxical in relation to peer review – as it illustrates, how peer review failed repeatedly at the case of Aether and many related concepts. So I don’t expect, proponents of peer review will hurry with peer review of AWT. In less opened forum, then the Internet such theory would never survive peer review by its very nature.

    AWT illustrates, how omni-directional energy spreading through particle fluctuations leads to interference of each wave with itself in less or more distant perspective. Therefore blind application of peer review can become divergent and misleading by the same way, like the ignorance of critique. After all, black hole event horizon is nothing else, then the example of such singular divergence.

  7. Eric Baird says:

    I think this subject’s likely to be running for a good few more years yet. One aspect of the problem that isn’t usually mentioned in the research papers is that we do //appear// to have a method of attack available to us that would //seem// to resolve the current discrepancy between GR and QM … but it’s not considered acceptable.

    We could try to rebuild general relativity so that it reduces to a relativistic acoustic metric rather than to the Minkowski metric of special relativity, and that would seem to produce porous, fluctuating horizons that’d appear to fix the black hole information paradox … but it’s such an extreme option that researchers are still trying out every other possibility that they can think of first.

    If, five or ten years from now, they still can’t get anything else to work (and they’ve been trying for a while), the community might eventually have to start thinking about that “total rewrite” option. But I don’t think that you’ll see mainstream researchers wanting to be associated with the idea until they’re pretty sure that all the alternatives have been exhausted. So what’s happening meanwhile is that the guys are running through the options again and again, and firming up some of the more obscure suggestions, to see if there’s any other possible option at all that could solve this thing, that they might have missed.