Re: OT, and religeous

Andreas Johansson wrote:

>Quoting Joe <joe@...>:
>
>
>
>>Andreas Johansson wrote:
>>
>>
>>
>>>Quoting Chris Bates <chris.maths_student@...>:
>>>
>>>
>>>
>>>>Since the concensus seems to
>>>>be that the universe is finite,
>>>>
>>>>
>
>
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>>>Really? All popular cosmology works from recent years I've read have said
>>>
>>>
>>it's
>>
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>>>probably not.
>>>
>>>
>>>
>>Really?  I find that very surprising.  All the stuff I've read suggest
>>that it's boundless, but finite.  Like the surface of a sphere.
>>
>>
>
>Very briefly, an expanding general relativistic universe can have three overall
>shapes; spherical, flat, hyperbolic. In the first case, it's boundless but
>finite, in the two later, both boundless and infinite. The parameter
>determining which is the mean matter density; if high, spherical, if low,
>hyperbolic, with flat at the critical value. It's used to be thought that the
>spherical version was the most likely, but observations in recent years seem to
>have established that we're well with the hyperbolic regime.
>
>
Interesting.  Can you explain to me what exactly the hyperbolic shape
implies - I do, I'm afraid, have a very limited grasp of non-Euclidean
geometry (especially in three dimensions).

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