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Re: [Phys-L] Big Bang



What is the evidence that the volume of the universe is finite? I'm not claiming that it is infinite--I'm just unaware that it has been ruled out.

-----Original Message-----
From: Phys-l [mailto:phys-l-bounces@phys-l.org] On Behalf Of Anthony
Lapinski
Sent: Thursday, March 14, 2013 1:10 PM
To: Phys-L@Phys-L.org
Subject: Re: [Phys-L] Big Bang

I am still confused with all of these ideas.

Unless I am mistaken, the current thinking is that the universe is finite.
So how do you get a finite amount of mass into essentially zero volume?
Everything has volume!

It makes more sense if the universe has an infinite amount of mass in it, but
we have know way of ever knowing this.

I would think that the early universe had a "minimal" size, not "zero"
size.

Phys-L@Phys-L.org writes:
I am certainly not up to speed here, but if the mass of the universe
was infinite wouldn't the mass density still be infinite? Isn't the
fact that the current observed (local) density is not infinite preclude
infinite mass. Infinite density at the time of the Bing Bang is still
possible with zero volume, but I would think not infinite mass??


R.W.Tarara

free Physics Instructional Software
www.saintmarys.edu/~rtarara/software.html


----- Jeffrey Schnick <JSchnick@Anselm.Edu> wrote:
This is a side issue, but I think that in arriving at the size of the
universe at the time of the big bang, based on the essentially infinite
density of the universe at that time, one assumes that the universe is
currently a sphere of diameter 14 billion light years with us at the
center. I think that the size that they are actually talking about is
the size of that portion of the universe which is visible to us and
that they should refer to it as such.

I think that in arriving at the size of the universe one assumes that
there is a finite amount of mass in the universe in which case infinite
density implies infinitesimal diameter. I don't think we have evidence
that the mass of the universe is finite. I don't think we can rule out
infinite density and infinite diameter at the time of the big bang.

-----Original Message-----
From: Phys-l [mailto:phys-l-bounces@phys-l.org] On Behalf Of
Anthony Lapinski
Sent: Thursday, March 14, 2013 9:38 AM
To: phys-l@phys-l.org
Subject: [Phys-L] Big Bang

I'll be teaching cosmology next month in my (high school) astronomy
class.
The book I use discusses inflation and that the volume of the
universe during
the Big Bang was less than the size of a proton! How can this be? I
realize the
universe had a "hot" and "dense" beginning, but isn't there a limit
to how
closely matter (made up of particles) can be packed together?
Particles take up space, so how could an object -- let alone the
entire
universe -- have essentially "infinite" density (zero volume)?

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_______________________________________________
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_______________________________________________
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_______________________________________________
Forum for Physics Educators
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