Re: Is the universe spatially infinite?
From: dkomo (dkomoNoSpam_at_cris.com)
Date: 08/02/04
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Date: 02 Aug 2004 17:14:43 EDT
[fixing the formatting of my last post]
Sam Wormley wrote:
>
> Perfectly Innocent wrote:
> >
> > dkomo <dkomo871@comcast.net> wrote in message news:<4_GdnbleifY6G5DcRVn-jA@comcast.com>...
> > > I need a definitive answer to two questions:
> > >
> > > 1. does the fact that space is flat imply that the universe is spatially
> > > infinite?
> >
> > No. Conceivably, the geometry of our universe could be that of a flat 3-torus.
> >
>
> Spacetime flat on the cosmic scale and curved locally where there
> is mass. The Sun is an excellent of a mass causing spacetime
> curvature of our solar system.
>
> The CMB data fits a model of a flat universe. See below.
>
I was trying to get a verification of the following quotes:
"But if the universe is spatially infinite, there was already an
infinite spatial expanse at the moment of the big bang. At this
initial moment, the energy density soared and an incomparably large
temperature was reached, but these extreme conditions existed
everywhere, not just at one single point. In this setting, the big
bang eruption took place everywhere on the infinite expanse.
Comparing this to the conventional single-dot beginning, it is as
though there were many big bangs, one at each point on the infinite
spatial expanse."
Brian Greene, _The Fabric of the Cosmos_, p. 249
Why should we take this idea seriously? Because,
"We will see that there is mounting evidence that the overall shape of
space is not curved, and since there is no evidence as yet that space
has a video game shape [a 3-D torus], the flat, infinitely large
spatial shape is the front-running contender for the large-scale
structure of spacetime."
Greene, p. 250
So what I got was a bunch of conflicting information in this thread.
Several people denied that spacetime is flat on a cosmic scale, even
though this is a key prediction of inflation theory and has been
verified by CMB measurements. And you claimed "that 12 to 14 billion
years ago, the portion of the universe we can see today was only a few
millimeters across", which is not correct if the universe is spatially
infinite.
--dkomo@cris.com
> 13.7 billion years +/- 0.2 Gyr (WMAP data of the CMB) which is good
> agreement with the oldest stars, the Hubble expansion rate as determined
> independently by cephied variables and Type Ia supernovae data.
>
> MAP Data Released!
> Ref: http://www.astro.ucla.edu/~wright/cosmolog.htm#News
>
> 11 Feb 2003 - The results from the first year of observing by the
> Wilkinson Microwave Anisotropy Probe were announced today at a Space
> Science Update in the auditorium of NASA HQ. Important results
> include:
>
> o The satellite has been renamed in honor of the late David T.
> Wilkinson of Princeton University, a key member of the project from
> its conception.
>
> o The polarization of the microwave background anisotropy coming
> from scattering by electrons 200 million years after the Big Bang
> has been detected. This is evidence for an early generation of
> stars existing 4 to 5 times earlier than any object yet observed.
>
> o The WMAP data agree with previous work showing the Universe is
> flat and in an accelerating expansion.
>
> o The WMAP data give the most precise values for the density of
> ordinary [baryonic] matter made of protons and neutrons and for the
> dark matter: 0.4 and 2.5 yoctograms per cubic meter. These
> correspond to omega_b = 0.0224 +/- 0.0009 and omega_m = 0.135 +/-
> 0.009.
>
> o The WMAP data give the most precise value for the age of the
> Universe: 13.7 +/- 0.2 Gyr. The Hubble constant is Ho = 71 +/- 4
> km/sec/Mpc, and the vacuum energy density corresponds to lambda =
> 0.73 +/- 0.04. 13 papers by the science team and the maps and
> power spectra are available by clicking on http://cmbdata.gsfc.nasa.gov
>
> See: http://www.astro.ucla.edu/~wright/cosmolog.htm#News
>
> Suggestion: Spend some time with Cosmology FAQs
> http://www.astro.ucla.edu/~wright/cosmology_faq.html
>
> And Ned Wright's Cosmology Tutorial
> http://www.astro.ucla.edu/~wright/cosmolog.htm
>
> Observational and Experimental Evidence Bearing on General Relativity
> http://math.ucr.edu/home/baez/RelWWW/tests.html
>
> General Relativity Tutorial
> John Baez
> http://math.ucr.edu/home/baez/gr/gr.html
>
> Relativity on the World Wide Web
> http://math.ucr.edu/home/baez/relativity.html
>
> General Relativity and Cosmology FAQs
> http://math.ucr.edu/home/baez/physics/
>
> Developments in General Relativity: Black Hole Singularity and Beyond
> http://arxiv.org/abs/gr-qc/0304052
>
> Improved Test of General Relativity with Radio Doppler Data from the Cassini Spacecraft
> http://arxiv.org/abs/gr-qc/0308010
>
> What is the experimental basis of Special Relativity?
> http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.htm
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