Re: Red shift and homogeneity

"Jim Greenfield" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> "George Dishman" <[EMAIL PROTECTED]> wrote in message
news:<[EMAIL PROTECTED]>...
> > "Jim Greenfield" <[EMAIL PROTECTED]> wrote in message
> > news:[EMAIL PROTECTED]
>
> This is a bit like our conversation about expansion on the graph
> paper, and an indicated (to me) center. If the majority of matter is
> leaving said center, OK galxies can form and continue out ward. But if
> the matter is going equally in all directions, no expansion, as
> transfers are equal and opposite.

It is perhaps easier to visualise using Sean's description of the
infinite number of finite sheets of paper mapping everything. All
the sheets are expanding so they also have to move apart at the same
time. Now add to that the idea that some galaxies have random 'proper
motions' that carry them across their sheet. Those near the edges may
cross to an adjacent sheet but if you focus on any edge, the motions
will be symmetrical on either side so the flows will be balanced. That
doesn't stop the sheets expanding and moving though.

> > > Distant galaxies have a speed of say 3000k/sec (is that about right?).
> >
> > The speed is proportional to the distance.
> >
> > > So if this is 1% c, then since BB they have only increased the
> > > distance from their point of formation relative to us by 1% of (say)
> > > 12 bly = 120 mly.
> > > What has been the expansion since BB?- surely more than 1%
> >
> > Objects near to us now have not moved far. Objects far away
> > have moved a long way - obviously ;-)
>
> Remember I am thinking of observed speed (per red shift) NOW; not
> calculated speed from an assumed situation.

You lost me there. The Hubble Law as you suggest applies 'now',
or along a surface of equal cosmological age. However we see
distant galaxies as they were in the past so conditions 'now'
have to be calculated by projecting forward, so when you say
"NOW; not calculated", this appears contradictory. Can you
clarify please.

> I think it much more likely that sunburn is caused by particles
> impacting on my skin, rather than something massless.

Sunburn is caused by the energy carried by the photons,
photons don't have mass.

> Gravity and
> magnetic fields may be massless entities,

Magnetic fields are photons, it's the 'M' in your 'EMR'.

> but I suggest that all other
> sub-atomic particles transfer mass because they ARE massive (but maybe
> only theoretically detectable)

"Mass" is just our name for bound energy. All particles transfer
energy.

> You accept that the galaxies have certain red shifts, because they
> were formed "on the move".

No, I accept that the galaxies have certain red shifts because
when their light is observed through a spectrograph we see the
characteristic lines of certain elements at wavelengths longer
than the same lines from similar galaxies nearer to us, or at
least I trust the astronomers who make and peer-review those
measurements.

I hypothesise that they were formed "on the move" because the
main constituent particles (neutrons, protons and electrons)
could only have formed atoms by cooling the mix so logically
the plasma must have been expanding before matter could form.

> But if the red shift is due to (say) the
> age at which it is seen, or its distance, or properties of light yet
> to be determined-- any of these may in the future torpedo expansion.

The first is known as 'evolution' and is perfectly reasonable
since the mix of elements in the universe is slowly changing.
For example in theory SNe might have had slightly different
light curves in the early universe since there was less of the
heavier elements around then. It's effect is considered as a
possible source of error in many studies. It cannot cause a
shift of atomic lines though it can affect their strength.

Distance, as in Tired Light, has been proven wrong many ways
but perhaps the most familiar to you is the Goldhaber paper
you read.

The only 'property' of light that matters in this context is
wavelength.

> > > > > > The volume of the balloon has a centre, the surface doesn't.
> > > > > > Imagine the universe was younger than it really is, 13.7 days
> > > > > > instead of 13.7 billion years. What you are saying is
> > > > > > analogous to "I have found the centre of the universe, it
> > > > > > is a fortnight ago!"
> > > > >
> > > > > If I deflate the balloon, the points on the surface still proceed
> > > > > towards a center though
> > > >
> > > > Sure, they proceed towards a time 13.7 billion years ago,
> > > > everywhere. That is not a location, it is a time.
> > >
> > > And they take the matter of the universe to that time???
> >
> > I don't believe in time travel.
>
> Me either! But it seems that you wish to subject space and its
> contents to different criteria.

No, I just want you to stop pretending that "last week" is
a location in space (even for very big values of 'a week').

> > No, just no centre. (If you want to deliberately avoid
> > understanding what I am saying, I'll play that game too.)
>
> No. I just stuck to my philosophical view that infinity cannot expand.
> I don't think that a mathematical formula will show otherwise.

Perhaps not mathematically but we did it logically with the
overlaid photocopied sheets, remember?

http://www.dishman.me.uk/George/Cosmology/Expansion/red.htm
http://www.dishman.me.uk/George/Cosmology/Expansion/green.htm

It is apparent from that demonstration that no point is any more
central than any other. Mathematically we showed that homogeneity
is maintained by the Hubble Law several different ways so you
cannot identify a centre by looking for the development of a
region of increased density. Sean's model of expanding and moving
sheets showed that there was no problem with infinity expanding
because more distant sheets are just moving out of the way faster,
and logically infinity cannot have a centre if the contents are
homogenous and isotropic because the centre would then be
equidistant between the edges and there are no edges.

> Settle George! Patience! I will continue to respect your scholarship
> and explanations- but reserve the right to apply logical arguement to
> demolish Relativity and BB

I respect your right to do that of course, but I would also
expect you to accept the results of those logical arguments
even if, to your possible surprise, they support those theories.
So far the logical arguments have all showed the BB model (the
real one, not the press version!) is entirely valid, though as
you have discovered it does not go back to zero time as you
had been led to believe. Let me repeat your own words:

> I just stuck to my philosophical view that infinity cannot expand.

We have shown that to be logically incorrect yet you hang on to
it for philosophical reasons. If you want to move the discussion
forward, you need to start accepting the logical conclusions of
our arguments even if they conflict with your intuition, otherwise
we will just go round in circles repeating those demonstrations.

We haven't really talked about relativity in any meaningful way so
I'll leave that for another day.

George