Astronomy Without A Telescope – Small Bangs


Most gamma-ray bursts come in two flavors. Firstly, there are long duration bursts which form in dense star-forming regions and are associated with supernovae – which would understandably generate a sustained outburst of energy. The technical definition of a long duration gamma-ray burst is one that is more than two seconds in duration – but bursts lasting over a minute are not unusual.

Short duration gamma-ray bursts more often occur in regions of low star formation and are not associated with supernovae. Their duration is technically less than 2 seconds, but a duration of only a few milliseconds is not unusual. These are assumed to result from collisions between massive compact objects – perhaps neutron stars or black holes – producing a short, sharp outburst of energy.

But there are also rare instances of gamma-ray bursts that don’t really fill either category. GRB 060614 is such a beast – and has been referred to as a hybrid burst. It had a long duration (102 seconds) but was not associated with a supernova. This finding was significant enough to warrant an article in Nature – with the lead author Gehrels stating ‘This is brand new territory; we have no theories to guide us.’

We should be grateful that no-one decided to call it a dark burst. And we are yet to see another such confirmed hybrid gamma-ray burst that might verify whether these are hybrid bursts are really something extraordinary.

Nonetheless, Retter and Heller have suggested we should consider the possibility that GRB 060614 might have been a white hole. A white hole is a theoretical entity – and arguably just an artifact of the mathematics of general relativity. Assuming a black hole is an object from which nothing can escape – then its symmetrical opposite would be a white hole into which nothing can enter – but which can radiate light and from which matter can and does escape.

Arguably the whole idea just arises because general relativity abhors sharp edges. So the argument goes that the space-time continuum should ideally extend indefinitely – being curved by massive objects, but never brought to an edge. However, black holes represent a pinch in space-time where everything is supposedly dragged into a point-like singularity. So, one solution to this problem is to suggest that a black hole is not an interruption to the continuum, but instead the space-time around a black hole is drawn into a narrow-necked funnel – essentially a wormhole – which then feeds through to a white hole somewhere else.

Left image: The mysterious hybrid gamma ray burst GRB 060614. Right image: The 'what goes in must come out' model of white holes - where a black hole is connected to a white hole - and the white hole is time-reversed so that it expels material in the past. This was an initially proposed as a solution to explain quasars in the early universe, but better explanations have come along since (e.g. supermassive black holes with jets).

Being opposites, a black hole in the present would be connected to a white hole in the past – perhaps a white hole that existed in the early universe, emitting light and matter for a period and then exploding – kind of like a film of the formation of a black hole run backwards. It’s been suggested that such white holes might have created the first anisotropies in the early isotropic universe – creating the ‘clumpiness’ that later led to galaxies and galaxy clusters.

Alternatively, the Big Bang might be seen as the ultimate white hole which expelled a huge amount of mass/energy in one go – and any subsequent white holes might then be ‘lagging cores’ or Small Bangs.

There are substantial theoretical problems with white hole physics though – for example, the matter it ejects should immediately collapse back down on itself through self-gravity – meaning it just becomes a black hole anyway, or perhaps it explodes. If the latter possibility is correct, maybe this is one possible explanation of GRB 060614 seen back in 2006. But it’s probably best to wait for another hybrid burst to appear and get some more data before getting too carried away here.

Further reading:
Retter and Heller The Revival of White Holes as Small Bangs.
The mysterious GRB 060614.
You can apparently create a white hole in your kitchen sink.

20 Replies to “Astronomy Without A Telescope – Small Bangs”

  1. This is a wonderful insight into the nature of black holes. Long have I personally pondered black holes, and if they do eventually spill out into the universe somewhere else. This theory of the white whole being the cause of the big bang leads to the possibility that the entire universe will end in one giant black hole!
    Check out my blog article introducing the big bang:

    1. Ryans;

      I posted a comment on your blog that should help clear some things up regarding Inflationary theory. This is really a challenging subject, glad to see your interest!

      1. It is definitely a subject of my personal interest. I love science that absolutely bends my view on reality! Following the theory that black holes are in fact tunnels (with possibly early white holes and everything seeming to have stemmed from a white hole) the equal and opposite reaction would have to be coming from a black hole somewhere in the future. If everything we see may have come from a white hole but didn’t end in a black hole, where did that matter come from then.

      2. The black holes are tunnels theory is not widely supported these days (it is quite an old idea).

        We can keep speculating that the energy/matter from this universe might have popped out from another universe – but at some point there should be a primordial source of all the energy/matter in the multiverse. Or otherwise energy/matter is eternal and just keeps getting shunted between universes. Or otherwise our universe is completely isolated and there was a something-out-of-nothing Big Bang that delivered the energy/matter of this universe.

      3. The more natural hypothesis is that FLRW universes are exactly zero energy, from having inflation making our type more or less exactly flat, so typically more or less exactly zero energy per volume.

        I see from Wikipedia [“Zero-energy universe”] that Hawking uses that, but it seems to be a result with old heritage. I knew about the dynamical systems approach showing this [Cooperstock, F.I.;Faraoni,V.(2003) – Ap.J. 587,483.], but apparently one can also show it by GR pseudo-tensors (Berman, arXiv:gr-qc/0605063v3).

        Then all the problems of sources, sinks and transport of energy falls.* Instead as Cooperstock and Faraoni mentions new universes can tunnel into being from old ones, which is akin to something-out-of-something (universe out of universe) or nothing-out-of-nothing (zero energy out of zero energy). =D

        * A new problem is that zero energy objects should be eternal in their reference frame, from classical correspondence relations used on energy-time observables. Zero energy corresponds to infinite time.

        Well, our own LCDM standard cosmology is future eternal, possibly past eternal if eternal inflation is true. But this may demand it for all FLRW universes.

        In my opinion this would be easiest realized by eternal inflation being generic for them. (So shortlived ones with “wrong” parameter sets would be rendered harmless for the hypothesis, by being embedded in the larger eternal inflation multiverse.)

  2. I have my doubts about this. The white hole is a sort of time reversed black hole. So a white hole would be this source of mass-energy that comes rushing out. A black hole is the top half and the bottom half of the Penrose diagram for the Schwarzschild spacetime solution. This can be seen on wikipedia. The physical black hole truncates this bottom half off. The Schwarzschild solution is a mathematical idea, sometimes called the eternal classical vacuum solution. The presence of matter tends to perturb the pure solution in a way which destroys the while whole portion of the solution.

    White hole may play a role during inflationary cosmology. The exponential flattening of space means that mass-energy clumps which might have existed in the past were smoothed out. So if we rewind this picture smooth matter clumps up, and it might clump up into black holes in this time reversed picture. So now let the video now go forwards and this is exactly what a white hole is. If this is the case there is an apparent asymmetry between the role of a black hole and a white hole, where the white hole might only be some manifestation of the earliest universe, maybe where gravitation is quantum mechanical.

    Yet I can’t quite understand how a white hole might pop into space as is what is proposed here. The idea for a number of reasons seems implausible.


    1. I agree completely.

      A white hole completely contradicts the second law of Newton. Succes with it.

      1. I don’t think white holes particularly violates Newton’s second law of
        motion. It is part of a solution to the Einstein field equation, which in a
        weak field limit recovers Newton’s second law of motion with gravity.

        A white hole is similar to what Freeman Dyson proposed with the
        electromagnetic field. He wrote a little article where he looked at what
        would happen if we let the electron charge change as e –> ie, i = sqrt{-1}.
        Electron positron pairs in the vacuum would repel each other and coming
        rushing out in a huge fountain-like flow. The universe would be filled with
        horrendous amounts of radiation and the quantum vacuum would be unstable.
        The white hole is similar in a way, for gravity is reversed and mass-energy
        comes rushing out of it. This seems to reflect some part of a solution
        which is not stable quantum mechanically.


  3. What’s the connection between the GRB and the white hole in particular? Is there a verifiable theory?

    According to Wikipedia, Stephen Hawking thinks that black holes and white holes are the same. That argument sounds pretty convincing.

    The violent final evaporation of a micro black hole would be a fair-sized explosion, but not of GRB magnitude.

    1. GRB 060614 is a bit mysterious, but I think the authors go a bit far in suggesting it represents a new class of GRBs. To date it looks like an isolated anomaly.

      Otherwise their premise is largely that GRB 060614 is evidence in search of theory and white holes are theory in search of evidence – so let’s join the dots. It’s an interesting idea, but certainly not verified theory.

  4. While I am in on way capable to argue the basic premise of white holes, be they real or not, the statements by the writers of the article indicate there is NO preferred location for white holes and as the universes contains ~99% of basically empty space why are there no white holes in intergalactic space. An event in a void would be more than convincing.

    1. You raise a very interesting point. If a white hole were to emerge in our universe one might suspect it could come into our space anywhere. Since most of the universe is empty space between galaxies one might expect a high probability for a large white hole to emerge there.

      Unfortunately I can’t attach images to illustrate the Schwarzschild solution in a Penrose diagram. However, the white hole is really the symmetrical half of the space which contains the black hole. The singularity on the bottom half corresponds to the white hole and the top the black hole. This Penrose diagram can be seen at: where the top left is the pure vacuum solution, and below it is the truncated version, which corresponds to the perturbation from matter.

      The white hole may have some correspondences with the negative energy states in quantum mechanics. These states for the theory of Fermi-Dirac particles form the Dirac sea, and for a set of virtual quantum states. If these states are perturbed by positive energy they can produce anti-matter. By the same token the white hole part corresponds to black hole quantum Hawking radiation. If one impacts this with the exterior vacuum of positive energy it manifests itself in the quantum tunneling of particles out of the black hole. In that way a black hole is not perfectly black, but it has a slight glow, or it is a grey hole. This has a strange connection to the arrow of time as well, and Hawking radiation that quantum tunnels information out of a black hole is a sort of “time machine.”


  5. While I am in on way capable to argue the basic premise of white holes, be they real or not, the statements by the writers of the article indicate there is NO preferred location for white holes and as the universes contains ~99% of basically empty space why are there no white holes in intergalactic space. An event in a void would be more than convincing.

  6. White holes have all sorts of problems. I am nicking this from the homepage of Andrew Hamilton at the UoC @ Boulder Dept. of Astrophysical and Planetary Sciences: white holes violate the 2nd law of thermodynamics. (GR doesn’t know about TD.)

    Hamilton doesn’t explain why, but if you think about it the system is curiously asymmetric. Black holes are consistent with TD whether they are alone or connected to WHs. BHs gobble up matter and disperse the resulting information to the universe by Hawking radiation to preserve unitarity of quantum physics.

    WHs are time reversed BHs. If they would be unconnected with BHs WHs would violate TD by absorbing dilute information from the universe and spit out complicated objects.

    So now you need a wormhole connection for the objects to travel between BH to WH to preserve TD. WoHs have their own problems…

    1. To expand what you are saying, white holes as time reverse black holes generate a large number of degrees of freedom from a compact configuration. This is a reversal of black hole thermodynamics. A black hole has its area define an entropy S = (k/4)A/L_p^2 for k the Boltzmann constant, A = 4?R^2 the area of the event horizon for a black of radius R = 2GM/c^2, and L_p the Planck unit of length L_p = sqrt{G?/c^3}. This is the Bekenstein-Hawking formula, which is calculated by working out how many harmonic oscillator degrees of freedom can compose a black hole. Putting all of this together we get

      S = 2?k(G/c?)M^2.

      The term sqrt{?c/G} = M_p, the Planck mass, which is a fundamental unit of mass in quantum gravity units. We then have that (M^2/M_p) = N, which is the number of units of Planck mass squared. 2?N = n is also the number of Planck units of area on the event horizon. The number of these units is then the measure of the entropy of the black hole S = nk, which should be familiar to those who have taken a thermodynamics course.

      The number of Planck units of area on the event horizon is a measure of how many microstates are coarse grained into a macrostate which defines the black hole. A white hole does something opposite, where the event horizon shrinks to zero and those microstates come flying out into the exterior world. This means that dS/dt < 0, and we have a little problem with the thermodynamics of spacetime physics.

      The pure mathematical solution does have a complete symmetry between the black hole and white hole portions of the solution. However, this is a classical solution which pertains in some ways to a quantum instanton of the gravity field. It is really a sort of “gadget” which has some connection to the underlying quantum mechanics of gravity.


  7. From what I understand of general relativity, a white hole in existence can persist forever but MAKING one is impossible. But I do not mind scientists proposing it as a hypothesis. When confronted with a totally new phenomenon, the old “throw every crazy idea you can think of at it” approach is perfectly legit. Something will stick eventually.

  8. This is thinking from my own head and not relying on any theories stated by anyone else.

    If a white hole is time reversed, shouldn’t a white hole just be a seemingly ordinary black hole, taking into account our own time direction?

    If this GRB is in fact a white hole, shouldn’t the fact that we saw it happen in our own time direction, mean that the black hole that swallowed the matter and energy, was the time-reversed object, in respect to our time direction? and that the mentioned black hole , to us in our time direction, would also appear to us as a white hole (e.g. another GRB with same properties, but at a different time/place?

Comments are closed.