Re: [Phys-L] Big Bang

[Jeffrey Schnick <JSchnick@Anselm.Edu>]

> -----Original Message-----
> From: Phys-l [mailto:phys-l-bounces@phys-l.org] On Behalf Of Richard Tarara
> Sent: Thursday, March 14, 2013 12:21 PM
> To: Phys-L@Phys-L.org
> Subject: Re: [Phys-L] Big Bang
>
> 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? 

Not if the volume is 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
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>
> ----- 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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