Re: PHYSICS: Time to collapse of universe?

Hara Ra (
Thu, 09 Jan 1997 01:35:11 -0800

Anders Sandberg wrote:
> > the ultimate
> > constituents of an open universe with proton decay might be positron-electron
> > pairs orbiting common centres of gravity.

> This sounds reasonable, but quite unstable; the positronium will radiate
> away its angular momentum and slowly spiral into anihilation in this
> scenario, unless it could in some way be refreshed.

Not quite. Positronium is quantized just like a hydrogen atom is; the
and positron's wave functions overlap and it vanishes as a pair of .511
MEV gamma
rays. I don't recall the lifetime, something like a few microseconds.

| Hara Ra <> |
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