A story about Python... sort of

[Erik Max Francis]

John J Lee wrote:

> A Google result (appropriately enough, given the origin of
> the name Google) ...

But the origin of the name was generated from a misspelling of _googol_
(the name for 10^100), which evidently was found via Web searches.  So
the origin of the name of the search engine

> ... suggested 10**120, and I seem to have a number in my head
> of 10**80 non-virtual particles in the universe (though I've no
> recollection where *that* number came from either!-).

Typically the total number of elementary particles in the observable
Universe is given as 10^80.  But when you're talking about such rough
estimates, the difference between 10^80, 10^100, and 10^120, although
incredibly huge, aren't all that much.  What's twenty or forty orders of
magnitude between friends?

Note that the qualification "observable Universe" here is crucial.  We
can only see to the edge of the cosmological horizon, where due to
cosmological expansion, particles are receding at greater than the speed
of light.  This is due to the finiteness of the speed of light and the
fact that the Universe is not infinitely old.  As time progresses, we'll
see more of the Universe, and so the observable Universe will increase
in size.

In standard Friedmann-Robertson-Walker models, you have open, flat, or
closed universes.  Recent observations seem to suggest that we live in
an open universe -- one which will continue to expand forever until
matter itself decays.  In FRW models, open (and flat) universes have
infinite spatial extent.  So, presuming we live in a universe that
follows this models, the true Universe is infinitely large, even though
we can only see a finite, small part of it.

> Possibly there is a quantum algorithm that makes use of many universes
> to
> solve the problem, though (no I'm not joking: the many-worlds
> 'interpretation' is widely accepted amongst physicists working on
> quantum
> computation).

Since it's an interpretation, though, it's just an intuitive way of
looking at the situation.  Quantum mechanical interpretations do not
modify the theory itself; that is, they neither add nor subtract
anything from the theory which is testable in any way.

-- 
   Erik Max Francis && max at alcyone.com && http://www.alcyone.com/max/
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