Re: cosmology and quantum gravity

[Rodney Dunning <dunnirb4@WFU.EDU>]

Zach Wolff wrote:

> An interesting problem for any attempts at a theory of
> quantum gravity popped into my head tonight:
> 1. Given black holes exist
> 2. By definition nothing from within the event horizon
> ever escapes beyond the event horizon.
> 3. The gravitational effects of a black hole are
> observable from beyond the event horizon.
> 4. The gravitational effects are mediated by
> gravitons.
> 5. The gravitons that would mediate these effects must
> originate within the event horizon.
> 6. For the effects to be observable outside the event
> horizon the gravitons must travel beyond the event
> horizon.
> ----
> By contradiction one or more of the above postulates
> is false.  To me, 4 seems like the most likely
> candidate.

Hi Zach,

I would look at 2 more carefully. How does 2 account for Hawking radiation?
And what about a black hole with a static electric field? Aren't (some kind
of ) photons involved? (Do a web search on "virtual photons" or "virtual
particles.")

> Does anyone know of an attempt of a quantum theory of
> gravity to overcome this inconsistency?

My first guess is "virtual" gravitons, but this isn't my specialty.

--
Rodney Dunning
dunnirb4@wfu.edu
http://www.wfu.edu/users/dunnirb4