In the News: 5D Strings & Black Holes

[CraigS]

In the News:

One for the theoreticians/mathematicians ....

"Physicists investigate fate of five-dimensional black strings"

While black holes in four-dimensional space-time are stable and can persist for a long time, their higher-dimensional analogues are usually unstable. One such theoretical analogue is a five-dimensional black string, which is unstable to perturbations and tends to decay into different forms. But like all unstable "black objects," it's difficult to determine what the end state of the perturbed system might be. Using a new computer code, physicists have been able to simulate the evolution of five-dimensional black strings well beyond earlier studies, leading them to predict that the strings eventually turn into five-dimensional black holes.
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The result is especially interesting because it could violate the cosmic censorship hypothesis. Formulated in 1969 by Roger Penrose, the cosmic censorship hypothesis says that there are no naked singularities other than the Big Bang singularity; all other singularities must be isolated from the rest of the universe by some kind of horizon. The purpose of cosmic censorship is to preserve the universe's causality, since a naked singularity would make causality break down and make it impossible to predict the behavior of future space-time based on the behavior of past space-time.
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Thus, if there are naked singularities in nature, there would be phenomena in the universe we can't explain by the theories we have. Some people (like Hawking) view this as 'anathema,' and think cosmic censorship is needed to prevent such a disaster; others (like Thorne), think it would be great if there were (benign) naked singularities, as this would give us a direct look into the inner workings of quantum gravity. I'm, (Lehner), in the latter camp!”

So, which camp are you in ?

Cheers

[renormalised (Carl)]

Here's one for ya....what if there are no singularities. Let's say that quantum gravity prevents the formation of singularities through the uncertainty principle. The singularity can't form because its energy and position have been smeared out. You can either define its position (which you could liken to a particle....a graviton) or its energy (warped spacetime), but in order for a singularity to exist you need both position and energy to be observable at the same time...which you can't at a quantum level.

[CraigS]

Originally Posted by renormalised

Here's one for ya....what if there are no singularities. Let's say that quantum gravity prevents the formation of singularities through the uncertainty principle. The singularity can't form because its energy and position have been smeared out. You can either define its position (which you could liken to a particle....a graviton) or its energy (warped spacetime), but in order for a singularity to exist you need both position and energy to be observable at the same time...which you can't at a quantum level.

I can get that. That's along the same lines as lab beam-splitter experiments underpinning quantum physics/uncertainty.

Better consult someone versed in quantum mathematics, though ..


Cheers