From: "Ralf Müller" <r_mueller@...>
Date: 2005-02-09T16:13:57+09:00
Subject: Re: [OT] Physics of black holes (Was: RubyConf '05)

On Mon, 7 Feb 2005 09:49:07 +0900
Caio Tiago Oliveira <caiot1@ibest.com.br> wrote:

> Tim Bates, 6/2/2005 18:52:
> > Josef 'Jupp' Schugt wrote:
> > 
> >> (...) The relative speed of galaxies for example is known to exceed
> >> the speed of light.
> > 
> > 
> > No, it's not. You've forgotten your elementary relativity. If you
> > have two galaxies on opposite sides of the universe (call them A and
> > B) with an observer in between (called O) then from O's frame of
> > reference the sum of the speeds of A and B might exceed c (the speed
> > of light), although neither galaxy's individual speed can exceed c,
> > BUT from A's frame of reference B's speed does not exceed c and vice
> > versa.
> > 
> > If this sounds bizarre and impossible to you, you haven't studied
> > physics.
> 
> 
> I studied physics and I agreed with Josef.
> The universe is in a expansion (an acelerated one). The universe wich is 
> visible to us is smaller than the whole universe, just because the 
> galaxies outside the visible universe are moving away from us faster 
> than the light they emit, so we never see this light.
> The faster the universe is expanding, less we can see, the near the 
> galaxies move away faster than the light.
> 
Again special relativity: c is the highest speed possible. What about this axiom? 
And how do you get any clue that galaxies (you don't even see) can move faster than light.