Re: accelerating universe and Leslie constraints/What's..

Nick Bostrom (
Sat, 27 Mar 1999 15:05:07 +0000

Damien Broderick wrote:

> Some time ago we had a discussion on the Doomsday arguments advanced
> by John Leslie and others. This spills over into anthropic
> cosmology, the Great Filter, etc. The Guardian published an account
> recently of a paper (posted on the Net) by Lawrence Krauss and Glenn
> Starkman, both of Case Western Reserve U., that the newly discovered
> acceleration of the observable universe implies a light-cone horizon
> that will isolate our local cluster some 100 billion years from now.
> The farthest galaxies will start to be carried away faster than
> light some 15 billion years hence.
> I wonder what impact this has on the Leslie argument?

None so far as I can see. If the new discoveries have a bearing on whether the universe (i.e. muliverse - the totality of everything that exists) is infinite or not, then they might be relevant however. At least the Doomsday argument is very problematic in the infinite case and might not work at all.

Michael S. Lorrey wrote:

> Gina Miller wrote:
> > Don't most physicists believe it's infinite?
> No they don't

I would think they do. The majority view favours an open or flat unievrse, both of which are currently spatially infinite.

Nick Bostrom Department of Philosophy, Logic and Scientific Method London School of Economics