Friday, July 28, 2023

The frozen star model of a black hole

In earlier blog posts we have claimed that a Schwarzschild black hole is essentially a "frozen star".


The frozen star model of a Schwarzschild black hole


Near the forming horizon of a Schwarzschild black hole, clocks tick extremely slowly, and the outermost shell of falling matter never quite reaches the forming horizon.

Inside the outermost forming horizon there may be other forming horizons from earlier matter shells which were dropped into the black hole.

In the case of an Oppenheimer-Snyder (1939) collapse, the collapse inside the forming horizon happens extremely slowly, and the surface of the dust ball never reaches the forming horizon.


Frozen in time


The basic idea is that at a low gravitational potential, local time runs ever slower. A black hole essentially is a collapse frozen in time.

In the syrup model of gravity, the viscosity of the syrup increases without bounds.


A global time in the system


The Schwarzschild external metric is static and it is easy to define a global time. Static observers at various places send light signals to each other, and use them to synchronize their clocks. Local time runs the slower, the closer we are to the horizon. The global time is the Schwarzschild coordinate time.

Inside the forming black hole, defining a global time is harder, and we do not have a mathematical formula for it. Since observers very close to each other can still send light signals to each other, we hope that a global time can be defined transitively: if adjacent observers 

       Aₙ and Aₙ₊₁

can synchronize their clocks, then we may be able to define a global time for a chain of observers

       A₀, A₁, A₂, ...

We believe that at a fundamental level, the system resides in Minkowski space, and distortions in clock speeds and distances are an artefact of the (newtonian) gravity field. If our hypothesis is true, then a global time can be defined: take any global time in the Minkowski space.

We conjecture that in the global time, the system essentially freezes.


Avoiding a singularity


An electron and a positron cannot fall into an "electric singularity" because they annihilate.

Classic newtonian gravity does allow a singularity to form. But if we add more complex effects of the gravity field, then we end up with the frozen star model, and avoid a singularity. General relativity can be regarded as nature's way of avoiding singularities – even though Roger Penrose and many other researchers in the 1960s believed that general relativity produces singularities.


Disassembling a black hole


If a black hole is a frozen star, it might be possible to disassemble it. Disassembling a singularity sounds like a hard thing – melting a frozen star sounds much easier.

So far, it looks like overspinning a black hole will disassemble it. The (fictitious) centrifugal force wins newtonian gravity. Matter inside the black hole will possess a lot of angular momentum and will be ejected away. The disassembling process might be quite quick, just like a collapse is.

We believe that we can overspin a black hole, using the rope pulling trick which we sketched on July 8, 2023.


Conclusions


Defining a global time is an essential step in proving that the frozen star model can work in general relativity. We will look at that problem in the future.

If we can disassemble a black hole, then a black hole is not an exotic object. A black hole is like a lump of syrup, nothing more. Exotic hypotheses about black hole thermodynamics, entropy, wormholes, white holes, string theories, and so on will be refuted; or, at least, those hypotheses become very improbable.

The black hole information paradox becomes a non-paradox: we can recover the fallen information from a black hole.

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