On Fri, Dec 08, 2017 at 12:59:16PM -0800, [email protected] wrote: > > > On Friday, December 8, 2017 at 3:04:42 PM UTC, [email protected] wrote: > > > > How is it distinguished from red and possibly blue shifting due to > > relative motion of distant galaxies? TIA, AG > > > > I meant to ask how one distinguishes the Doppler shift (red or blue) from > the Cosmological shift (red) for distant galaxies. TIA, AG >
The answer is you don't. However, for those galaxies we have an independent measure of distance (via so-called standard candles), the Hubble law holds (velocity away from us as measured by Doppler shift is on average proportional to the distance away). It is a reasonable extrapolation that the Hubble law holds for the entire visible universe. For the most distant galaxies, astrophysicists tend to quote their distance in terms of z factor, which is related to their Doppler shift, rather than an exlicit distance, as the latter vlaue is not model independent. Cheers -- ---------------------------------------------------------------------------- Dr Russell Standish Phone 0425 253119 (mobile) Principal, High Performance Coders Visiting Senior Research Fellow [email protected] Economics, Kingston University http://www.hpcoders.com.au ---------------------------------------------------------------------------- -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
