On Saturday, December 9, 2017 at 2:40:12 AM UTC, Russell Standish wrote: > > On Fri, Dec 08, 2017 at 12:59:16PM -0800, [email protected] > <javascript:> 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. >
I think what you're implying but not expressly stating is that if one measures the red shift and knows the distance, one then apply estimate the departure of the red shift from what Hubble's law implies, one can estimate the Doppler shift. AG > > 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] > <javascript:> > 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.
