Re: Symmetry

carlip-nospam@xxxxxxxxxxxxxxxxxxx wrote:

What we have here is a failure to communicate.


His name came to mind because I vaguely recalled his bet with Hawking.


Or read

http://www.gravity.psu.edu/news/newscientist.pdf
______________
The collapse of stars heavier than about 5 solar masses is particularly
disconcerting for cosmologists. In many scenarios, Einstein's theory
of general relativity predicts that the likely outcome is not a black
hole, as is popularly assumed, but a naked singularity - an infinitely
dense fireball in which the laws of physics break down. Unlike a black
hole, it is potentially observable. The known laws of physics would
misbehave wildly at these singularities and cannot predict what
astronomers studying such collapsing stars might see. To avoid such
anarchy cosmologists Roger Penrose, Stephen Hawking and others
hypothesised a "cosmic censorship principle" that would prevent such a
situation by cloaking all singularities within black holes, so they
could never be observed. But this hypothesis remains unproven.
________________

This is not a prediction of "the existence and observability of
singularities."

From my quote, we have:

"Einstein's theory of general relativity predicts that the likely
outcome is not a black hole, as is popularly assumed, but a naked
singularity".

and from Penrose "The Road to Reality", p . 767

" A naked singularity would be a spacetime singularity, resulting from
a gravitational collapse, which is visible to outside observers, so it
is not "clothed" by an event horizon".

So I interpret the quotes as a prediction of " the existence and
observability of singularities.

Maybe I'm wrong, but I am willing to consider your interpretation

If GR doesn't predict them, that's great - I'm wrong and so was the
webpage.

But I do I find it strange that so much is written about them.


Perhaps you interpret these writings in a different way than I do.

Evidently. I interpret "this hypothesis remains unproven," for example,
as meaning, "We don't know whether cosmic censorship is correct or not."
You, apparently, interpret it as implying "the existence and observability
of singularities."

No, I interpret that sentence the same way that you do.

In my language, "We don't know whether X can occur" does not have the same
meaning as "I predict X." Is your language different?

Apparently it is, because in my language, "Einstein's theory of
general relativity predicts... ...a naked singularity" means just
that. What does it mean to you?

Barry

.

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