From: Emlyn O'regan (oregan.emlyn@healthsolve.com.au)
Date: Thu Aug 15 2002 - 02:08:50 MDT
Thanks. I do love this list!
Emlyn
> -----Original Message-----
> From: Amara Graps [mailto:amara@amara.com]
> Sent: Thursday, 15 August 2002 17:11
> To: extropians@extropy.org
> Subject: RE: Nature Article
>
>
> Dear Emlyn,
>
> This might help. Your cosmology questions are common, don't worry.
> There is a huge amount of information here:
>
> Frequently Asked Questions in Cosmology
> http://www.astro.ucla.edu/~wright/cosmology_faq.html
>
> ----------------------
>
> What is the evidence for the Big Bang?
>
> The evidence for the Big Bang comes from many pieces of observational
> data that are consistent with the Big Bang. None of these
> prove the Big
> Bang, since scientific theories are not proven. Many of these
> facts are
> consistent with the Big Bang and some other cosmological models, but
> taken together these observations show that the Big Bang is the best
> current model for the Universe. These observations include:
>
>
> * The darkness of the night sky - Olbers' paradox.
> * The Hubble Law - the linear distance vs redshift law.
> The data are
> now very good.
> * Homogeneity - fair data showing that our location in
> the Universe
> is not special.
> * Isotropy - very strong data showing that the sky
> looks the same in
> all directions to 1 part in 100,000.
> * Time dilation in supernova light curves.
>
> The observations listed above are consistent with the Big Bang or with
> the Steady State model, but many observations support the Big
> Bang over
> the Steady State:
>
> * Radio source and quasar counts vs. flux. These show
> that the Universe
> has evolved.
> * Existence of the blackbody CMB. This shows that the
> Universe has
> evolved from a dense, isothermal state.
> * Variation of TCMB with redshift. This is a direct
> observation of
> the evolution of the Universe.
> * Deuterium, 3He, 4He, and 7Li abundances. These light
> isotopes are
> all well fit by predicted reactions occurring in the First
> Three Minutes.
>
> Finally, the angular power spectrum of the CMB anisotropy that does
> exist at the several parts per million level is consistent with a dark
> matter dominated Big Bang model that went through the inflationary
> scenario.
>
> ----------------------
>
> Are galaxies really moving away from us or is space just expanding?
>
> This depends on how you measure things, or your choice of coordinates.
> In one view, the spatial positions of galaxies are changing, and this
> causes the redshift. In another view, the galaxies are at fixed
> coordinates, but the distance between fixed points increases
> with time,
> and this causes the redshift. General relativity explains how to
> transform from one view to the other, and the observable effects like
> the redshift are the same in both views. Part 3 of the tutorial shows
> space-time diagrams for the Universe drawn in both ways.
>
> Also see the Relativity FAQ answer to this question.
>
> ----------------------
>
>
> --
>
> ********************************************************************
> Amara Graps, PhD email: amara@amara.com
> Computational Physics vita: ftp://ftp.amara.com/pub/resume.txt
> Multiplex Answers URL: http://www.amara.com/
> ********************************************************************
> "Dare to be naive." -- Buckminster Fuller
>
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