🚀 go-pugleaf

In article <92216.155158DOCTORJ@SLACVM.SLAC.STANFORD.EDU>, DOCTORJ@SLACVM.SLAC.STANFORD.EDU (Jon J Thaler) writes...
>This needs some clarification.  Even in the absence of deceleration,
>the Hubble constant changes with time.  It is empirically
>observed that the recession speed of galaxies (as measured by red shift)
>proportional to the distance.  The constant of proportionality has units
>speed/distance, usually given as (km/sec)/Megaparsec.  The same constant
>applies (more-or-less) to all cosmological objects.  Hence the use of the
>word "constant."
> 
>If one is clever, one notices that the dimensionality of the Hubble
>constant is inverse time.  In fact, in a big bang cosmology it tells you
>to within a numerical factor the age of the universe.  Thus, even if
>there is no deceleration the Hubble constant decreases as time passes.
>This is simply because the universe is getting older.  More prosaically,
>receding galaxies get farther away.

Now *I'm* confused.  Take a galaxy G at a distance D from us.  It
will be receeding at a speed of Ho*D up to some small peculiar velocity.
Say that in a few billion years (by which time I might even have tenure!) 
G is now twice as far from us.  Won't its recession speed be 2*Ho*D?
There is twice as much space expanding between us, so it should be receeding
at twice the speed.  

Your argument seems to suggest that recession speeds are fixed so that 
in a few billion years G will be twice as far from us, but still have 
the same recession speed, causing us to conclude that Ho has shrunk
to half its current value.

Where am I going wrong?

-Scott
--------------------
Scott I. Chase			"The question seems to be of such a character
SICHASE@CSA2.LBL.GOV		that if I should come to life after my death
				and some mathematician were to tell me that it
				had been definitely settled, I think I would
				immediately drop dead again."      - Vandiver