Popping The Big Bang

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"George Dishman" wrote in message
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Diagrams in Prof Wright's tutorial show red-shift increasing with
distance, but this is not Doppler.

Doppler is the most obvious explanation (though at
larger ranges you have to be careful about definitions)
and matches what we see. There are few alternative
explanations for the shift and none AFAIK that aren't
ruled out by other observations.
snip
But if the very distant bodies
were designated 0, then everything closer would have a blue shift.

If a train passes you in the station blowing its
whistle, the note is lower as it goes away from you.
If you designate the train as '0', the note is still
lower. Nature doesn't care about our designations.

But you (might) be making that arbitrary +/- (towards vs away) for
direction.
This 'human choice' has caused me grief in other posts. Reverse the
signage would reverse the direction???

No. The sound the whistle makes is carried to you as
waves of pressure in the air and they travel with some
speed. It takes time for them to reach you some when
you are listening to the sound, you are hearing waves
that were emitted some time ago. Waves emitted since
then haven't reached you yet, they are still in transit,
and the number of such waves between you and the whistle
depends on how far away it is.

Now if you walk towards the whistle and then stop, you
are now closer to it so there will be fewer between
you and it. Where did the missing waves go? The answer
is that you 'walked through them'. During the time
you are walking to towards the whistle, you hear a higher
rate of waves than when you are standing still.

The same thing happens if the whistle is moving towards
you, as time goes on, the distance reduces so the number
of waves in transit at any time is reducing. You hear
those extra waves as a higher note.

Conversely if the distance between you and the whistle
is increasing, then you hear a lower note. It doesn't
matter what combination of motion is responsible, the
number of waves in transit is (roughly) the distance
between you and the whistle divided by the speed of
sound. If that distance is increasing, the number is
increasing and that makes the note lower.

George, this is exactly why I can't see the Doppler connection.
The Dop shift occurs right by me as the train goes by. After that, the
whistle note has the same frequency- just a diminishing amplitude. I
can't tell how far away the train is by its whistle- only its
direction as it passes. This is an important point ??

It is very important indeed. Once the train has passed you
it travels at a constant speed away from you so you hear a
steady note but it is lower than you would hear if you were
on the train. How much lower the note sounds depends on the
speed of the train. Now suppose you are in a busy station.
100yds from you there is a goods train just pulling out at
a steady 10mph. A local train on another track is 200yds
away and moving smoothly at 20mph while the express just
went through and is 300yds down the track moving at 30mph.
What you hear is three notes from the three trains and the
further away the train, the lower the note you hear. That
is what we see when we look at galaxies, the red-shift
from each galaxy is proportional to its distance (and no,
the distance is not determined from the red-shift). We can
tell the shift because we can identify specific lines from
individual elements and compare them to the same lines
produced in the lab on Earth.

You should have been a science teacher

I'll take that as a compliment despite what you said
about teachers. Can I take it this means you now
understand the relationship?

Now imagine you had filmed those trains passing through
the station. Play the film backwards and you would find
they all passed you at the same time, about 20 seconds
before the moment I described above. For galaxies it is
more complex because the speed has been changing but the
logical conclusion is the same, they were all close
together some time ago, and it appears that was about
13.7 billion years ago.

Yeh
What a head-banger! Here again we have the material of the universe
close together 13.7bya, but a picture of the universe at that time
(the picture of the outer shell, that is), also 13.7bly away

Aye, there's the rub. This is what I meant when I said
distances were complicated in cosmology. We can go into
this in more detail but I'd like to resolve the Doppler
question first or the posts will become too unwieldy.

On CMBR:
EMR shining on black body (maybe dust or gas or larger lump of matter)
'warms' it, and this heat energy is then re-radiated, but at a longer
wavelength (this may be less energetic too).

A black body radiates at all wavelengths but there is a
peak in the spectrum. The wavelength of that peak and
the total power radiated depend only on the temperature
of the material. The temperature is stable if the total
power radiated is equal to the power absorbed. If it
absorbs more than it radiates then the temperature will
rise while if it absorbs less the temperature will fall.

This 'secondary EMR may
repeat the cycle with other black bodies many times.

Right. If things are stable for a long time, the energy
absorbed and emitted by each body will reach a balance.
The peak wavelength then tells us the average temperature.

The re-radiating
seems to based on a potential difference of heat between bodies,

[Nitpick: Temperature difference, not potential
difference.]

and
the CMBR is the lowest common denominator of wave length to this heat
potential. That is, bodies at 2.3K produce no further reduction and
just keep bouncing it around.

The power is proportional to T^4, for two otherwise
identical black bodies, one at 1.2K will radiate
16 times less heat than one at 2.4K.

However, think what the consequences of your suggestion
would be. We can see galaxies clearly with hardly any
blurring from dust in-between from over 12 billion
light years away, yet at 13.7 billion we see only an
opaque shell of material. Your alternative puts us at
the exact centre of a transparent sphere within a
relatively dense, cold, opaque gas cloud. Are you sure
that's what you want to suggest?

Because I subscribe to the idea that the sphere we can 'see' is only
due to the limitations of our vision, the concept of a 'center of the
universe' is anathema to me (that 1/0 thing). That 'transparent
sphere' might be analogous to peering into fog.

Yes, I use that analogy too but you have to be careful.
Present theory says the universe was filled with a very
uniform fog for the first 378,000 years. At that time
it cooled enough to become transparent so we see a shell
of the glow from that hot fog at about 13.7Gy range.
Since then, there was a brief period when it became
slightly misty, then it was cleared by the radiation from
the first stars.

The reason we think that is that for at least the last
12Gy, there is no evidence of any fog whatsoever,
everything is almost crystal clear. That's why I called
it transparent. The next generation of telescopes is
hoping to push that back so we see the very first stars
that ever formed.

An astronomer in a galaxy a billion light years from here
would see exactly the same as us, about 13GY of crystal
clear vacuum then the "dawn mist" of the CMBR.

Also, since we see a red shift for all distant galaxies,
there is every reason to think that, regardless of the
cause, it would affect the light from the black body
material too. That means we are at the coldest point
in a spherically symmetrical region that gets hotter
as you get further away from us. If not, we should
see a mix of wavelengths shifted from the uniform
peak emitted by the material. More distant material
must be hotter so that its peak is red-shifted to
exactly coincide with that of cooler, nearer material.
The spectrum we see is an exact fit for a single
layer of material, not a blend over distance.

I am suspicious here that the distance to that 'single layer of
material' is this reversed cat. If we could travel 2bly away, I
suspect the same spectrums looking in all directions would be
observed. Otherwise we really MUST be near the 'center.

That's what the Big Bang says which is why I am puzzled
that you are against it.

Because we know there has been no fog for billions of
years but the depth to which we can penetrate the fog
of the CMBR has been measured at a very small value
(I can't remember exactly but no more than a few 10's
of thousands of years), your alternative _does_ put us
in such a shell of material.

George

Hi Earl. Long time, no observe.

"GASNER" wrote in message
...

I am just lurking on the general discussion.

With respect to the "common misconception that the Big Bang occurred at a
point" . . . Yes indeed there is such a misconception of the Big Bang
theory.
It is promoted by a significant fraction of 'experts' who should know
better, .
. . on Radio, TV and in print. (NOT by you!) I have heard
astronomer/cosmologist after astronomer/cosmologist talk about the time
that
the universe was the size of a grapefruit (or plum, or pomogranite, or
whatever).

And all for the want of a single word, "observable". I think
it is said the size of the region we can now observe was the
size of a grapefruit when the era of inflation ended but I
could be wrong.

George

"G" == GASNER writes:

From: Joseph Lazio

JG Diagrams in Prof Wright's tutorial show red-shift increasing with
JG distance, but this is not Doppler. An ASSUMPTION must have been
JG made, that the universe was expanding faster at the earlier time,
JG which we are viewing at large distance. Bodies must have been
JG moving away relative to us at higher speed closer to the time of
JG BB. This whole red-shift thing is very problematical!

You seem to have fallen prey to the common misconception that the
Big Bang occurred at a point. It did not. It occurred everywhere.
We are not at the "center" of the Universe. Everything[*] is
getting farther away from everything else. All of the supernovae
are getting farther away from each other and from us. Yes, this is
difficult to visualize.

G I am just lurking on the general discussion.

G With respect to the "common misconception that the Big Bang
G occurred at a point" . . . Yes indeed there is such a misconception
G of the Big Bang theory. It is promoted by a significant fraction
G of 'experts' who should know better, . . . on Radio, TV and in
G print. (NOT by you!)

Thanks. Yeah, I know that many of my fellow astronomers continue to
spread this misconception.

G I have heard astronomer/cosmologist after astronomer/cosmologist
G talk about the time that the universe was the size of a grapefruit
G (...).

Actually, this isn't entirely wrong, if you read "universe" as
"observable Universe." A grapefruit is about 10 cm or 300
light-picoseconds across. Suppose you were able to be present in the
early Universe. When the Universe was only 300 light-picoseconds old,
you could see a region only about the size of a grapefruit.

G It reminds me of the story that my professor told me about hearing
G another professor give an incorrect explanation of something to a
G class. "I told him that what he was telling them was wrong and he
G replied that of course he knew that it was wrong, but that it was
G much easier for the class to understand!"

Well, there is some truth to that. When I was a freshman, one of my
teaching assistants said that physics instructions was a set of ever
decreasing lies. I was a bit surprised initially, but I now
understand what he meant. As a freshman one learns that this is
something called Faraday's Law, as a junior one learns about Maxwell's
equations and the dielectric constant, as a graduate
student one learns that it's really a dielectric tensor, ....

--
Lt. Lazio, HTML police | e-mail:
No means no, stop rape. | http://patriot.net/%7Ejlazio/
sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html

Dear Joseph Lazio:

"Joseph Lazio" wrote in message
...
"G" == GASNER writes:
....
G I have heard astronomer/cosmologist after astronomer/cosmologist
G talk about the time that the universe was the size of a grapefruit
G (...).

Actually, this isn't entirely wrong, if you read "universe" as
"observable Universe." A grapefruit is about 10 cm or 300
light-picoseconds across. Suppose you were able to be present in the
early Universe. When the Universe was only 300 light-picoseconds old,
you could see a region only about the size of a grapefruit.

*If* distance uses its current definition (of light times time), and *if* c
were near infinite at the time of the Big Bang, then the Universe could
easily be any finite size (in meters) you might imagine.

David A. Smith

"George Dishman" wrote in message ...
"Jim Greenfield" wrote in message
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"George Dishman" wrote in message
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"Jim Greenfield" wrote in message
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"George Dishman" wrote in message
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"Jim Greenfield" wrote in message
m...
Diagrams in Prof Wright's tutorial show red-shift increasing with
distance, but this is not Doppler.

But if the very distant bodies
were designated 0, then everything closer would have a blue shift.

If a train passes you in the station blowing its
whistle, the note is lower as it goes away from you.
If you designate the train as '0', the note is still
lower. Nature doesn't care about our designations.

But it doesn't get PROGRESSIVELY lower. An increase in the distance to
the train doesn't change the tone

But you (might) be making that arbitrary +/- (towards vs away) for
direction.
This 'human choice' has caused me grief in other posts. Reverse the
signage would reverse the direction???

No. The sound the whistle makes is carried to you as
waves of pressure in the air and they travel with some
speed. It takes time for them to reach you some when
you are listening to the sound, you are hearing waves
that were emitted some time ago. Waves emitted since
then haven't reached you yet, they are still in transit,
and the number of such waves between you and the whistle
depends on how far away it is.

It doesn't matter how many compressions are involved- the frequency
will be the rate at which they strike my ear (events/time)

Now if you walk towards the whistle and then stop, you
are now closer to it so there will be fewer between
you and it. Where did the missing waves go? The answer
is that you 'walked through them'. During the time
you are walking to towards the whistle, you hear a higher
rate of waves than when you are standing still.

Yes, but wherever I stand,(distance to train) the note will be the
same:
Amplitude (loudness)will vary only

The same thing happens if the whistle is moving towards
you, as time goes on, the distance reduces so the number
of waves in transit at any time is reducing. You hear
those extra waves as a higher note.

Are you pulling my chain George? It's a higher note, but will not
alter unless the train alters speed (or I do). You must know this!?

Conversely if the distance between you and the whistle
is increasing, then you hear a lower note. It doesn't
matter what combination of motion is responsible, the
number of waves in transit is (roughly) the distance
between you and the whistle divided by the speed of
sound. If that distance is increasing, the number is
increasing and that makes the note lower.

Your'e having me on!! The VELOCITY has to be changing to change the
note, not the distance.

direction as it passes. This is an important point ??

It is very important indeed. Once the train has passed you
it travels at a constant speed away from you so you hear a
steady note but it is lower than you would hear if you were
on the train. How much lower the note sounds depends on the
speed of the train. Now suppose you are in a busy station.
100yds from you there is a goods train just pulling out at
a steady 10mph. A local train on another track is 200yds
away and moving smoothly at 20mph while the express just
went through and is 300yds down the track moving at 30mph.
What you hear is three notes from the three trains and the
further away the train, the lower the note you hear.

Once again, the lower (different) note is due to velocity, not
distance. If the three trains went by at different intervals, but at
the same speed, some time later they would be at 100, 200, 300 yards,
but each whistle would have the same frequency (and a nice harmonic)



That
is what we see when we look at galaxies, the red-shift
from each galaxy is proportional to its distance (and no,
the distance is not determined from the red-shift).

If you persist with comparing sound to light (which I don't subscribe
to), my arguement above re sound Doppler, rebuts this 'red shift is
due to distance'.

Now imagine you had filmed those trains passing through
the station. Play the film backwards and you would find
they all passed you at the same time, about 20 seconds
before the moment I described above. For galaxies it is
more complex because the speed has been changing but the
logical conclusion is the same, they were all close
together some time ago, and it appears that was about
13.7 billion years ago.

You walked back Felix, George! You have looked at galaxy so and so,
measured a frequency, calculated a distance, and placed galaxy here
back when. Same with the others. But the assumptions that the trains
(galaxies) had a certain accelleration have been made. I'm having
trouble clarifying this, and sound Doppler doesn't help- photons and
compression waves really have BA in common, and only sow confusion.

Yeh
What a head-banger! Here again we have the material of the universe
close together 13.7bya, but a picture of the universe at that time
(the picture of the outer shell, that is), also 13.7bly away

Aye, there's the rub. This is what I meant when I said
distances were complicated in cosmology. We can go into
this in more detail but I'd like to resolve the Doppler
question first or the posts will become too unwieldy.

Me too--snip here until dust settles

Jim G

"Jim Greenfield" wrote in message
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...
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"George Dishman" wrote in message
...
"Jim Greenfield" wrote in message
m...
Diagrams in Prof Wright's tutorial show red-shift increasing
with
distance, but this is not Doppler.

But if the very distant bodies
were designated 0, then everything closer would have a blue
shift.

If a train passes you in the station blowing its
whistle, the note is lower as it goes away from you.
If you designate the train as '0', the note is still
lower. Nature doesn't care about our designations.

Jim, there seems to have been some confusion here, you
seem to think I am suggesting that a fixed distance
will cause a change of note. That is obviously not the
case and I am not suggesting it would. I'll answer your
points individually but please bear this in mind as you
read my replies.

But it doesn't get PROGRESSIVELY lower. An increase in the distance to
the train doesn't change the tone

Correct. The note depends on the speed and a constant
speed gives a constant note.

But you (might) be making that arbitrary +/- (towards vs away) for
direction.
This 'human choice' has caused me grief in other posts. Reverse the
signage would reverse the direction???

No. The sound the whistle makes is carried to you as
waves of pressure in the air and they travel with some
speed. It takes time for them to reach you some when
you are listening to the sound, you are hearing waves
that were emitted some time ago. Waves emitted since
then haven't reached you yet, they are still in transit,
and the number of such waves between you and the whistle
depends on how far away it is.

It doesn't matter how many compressions are involved- the frequency
will be the rate at which they strike my ear (events/time)

Right. Now if the source emits at rate 'a' events/second
and a constant number of waves are in transit (zero speed)
then you hear the same rate. If you are walking away from
source, the number in transit is increasing so the rate
you hear must be lower than 'a'. Walk towards the source
and the rate will be higher than 'a' (but still a constant
rate for constant speed).

Now if you walk towards the whistle and then stop, you
are now closer to it so there will be fewer between
you and it. Where did the missing waves go? The answer
is that you 'walked through them'. During the time
you are walking to towards the whistle, you hear a higher
rate of waves than when you are standing still.

Yes, but wherever I stand,(distance to train) the note will be the
same:
Amplitude (loudness)will vary only

Right, but during the time you were walking, more waves
must have reached your ear so the note is as emitted
while you stand but must be higher while you are
walking towards the source. Remember the context, I
was trying to show why the note will always be higher
if the distance between you and the sourse is reducing
and lower if it is increasing.

Amplitude will vary as you say but that's not in dispute
so I haven't mentioned it.

The same thing happens if the whistle is moving towards
you, as time goes on, the distance reduces so the number
of waves in transit at any time is reducing. You hear
those extra waves as a higher note.

Are you pulling my chain George? It's a higher note, but will not
alter unless the train alters speed (or I do). You must know this!?

Yes of course, I was showing that you couldn't change
it to be lower instead of higher just by changing the
coordinates you use to describe the effect. Remember you
said: "But if the very distant bodies were designated 0,
then everything closer would have a blue shift." That is
not true, a blue shift occurs when the distance is
reducing. For example the Andromeda Galaxy has a blue
shift because it is moving towards us.

Conversely if the distance between you and the whistle
is increasing, then you hear a lower note. It doesn't
matter what combination of motion is responsible, the
number of waves in transit is (roughly) the distance
between you and the whistle divided by the speed of
sound. If that distance is increasing, the number is
increasing and that makes the note lower.

Your'e having me on!! The VELOCITY has to be changing to change the
note, not the distance.

For a given velocity, you get a given note. If the
velocity changes, the note changes. Zero velocity
means you hear the same note that was emitted. You
say this in your next paragraph.

direction as it passes. This is an important point ??

It is very important indeed. Once the train has passed you
it travels at a constant speed away from you so you hear a
steady note but it is lower than you would hear if you were
on the train. How much lower the note sounds depends on the
speed of the train. Now suppose you are in a busy station.
100yds from you there is a goods train just pulling out at
a steady 10mph. A local train on another track is 200yds
away and moving smoothly at 20mph while the express just
went through and is 300yds down the track moving at 30mph.
What you hear is three notes from the three trains and the
further away the train, the lower the note you hear.

Once again, the lower (different) note is due to velocity, not
distance.

Right.

If the three trains went by at different intervals, but at
the same speed, some time later they would be at 100, 200, 300 yards,
but each whistle would have the same frequency (and a nice harmonic)

At the same speed, yes. But in the paragraph above the
speed for each train is _different_. I thought you had
picked that up last time.

That has two important effects, first the note from each
train is different (though for each it is constant if
the speed is constant as you said) and secondly the time
since the train passed you is the same for all the trains.

That
is what we see when we look at galaxies, the red-shift
from each galaxy is proportional to its distance (and no,
the distance is not determined from the red-shift).

If you persist with comparing sound to light (which I don't subscribe
to),

There is a slight difference but it is negligible at
the speeds we are dealing with, the first-order effect
predominates and that is the same as sound. We can talk
about it separately if you like.

my arguement above re sound Doppler, rebuts this 'red shift is
due to distance'.

We know from lab experiments that for speeds much less
than the speed of light, red-shift is proportional to
speed. What we find by measurement is that there is a
trend in the red-shift of galaxies, the red-shift is
proportional to distance. We conclude from those two
that there is a trend in the speed of galaxies, that
more distant galaxies are moving away from us at
greater speeds.

Now imagine you had filmed those trains passing through
the station. Play the film backwards and you would find
they all passed you at the same time, about 20 seconds
before the moment I described above. For galaxies it is
more complex because the speed has been changing but the
logical conclusion is the same, they were all close
together some time ago, and it appears that was about
13.7 billion years ago.

You walked back Felix, George! You have looked at galaxy so and so,
measured a frequency, calculated a distance,

Nope, calculated a speed, measured the distance.

.. We can go into
this in more detail but I'd like to resolve the Doppler
question first or the posts will become too unwieldy.

Me too--snip here until dust settles

Agreed. Jim, I am not saying anything that contradicts
your views here. If you think I have, re-read it, I may
just have written it in a confusing manner.

George

Subject: Popping The Big Bang
From: "George Dishman"
Date: 9/26/03 10:04 AM Central Daylight Time
Message-id:

Hi Earl. Long time, no observe.

"GASNER" wrote in message
...

I am just lurking on the general discussion.

With respect to the "common misconception that the Big Bang occurred at a
point" . . . Yes indeed there is such a misconception of the Big Bang
theory.
It is promoted by a significant fraction of 'experts' who should know
better, .
. . on Radio, TV and in print. (NOT by you!) I have heard
astronomer/cosmologist after astronomer/cosmologist talk about the time
that
the universe was the size of a grapefruit (or plum, or pomogranite, or
whatever).

And all for the want of a single word, "observable". I think
it is said the size of the region we can now observe was the
size of a grapefruit when the era of inflation ended but I
could be wrong.

George


Hi George.

Well, it 'could' mean how far you can see, but I would consider that a strange
definition of size. If our present universe was a few zillion times as dense,
then you couldn't see very far without being obstructed by a star, (see
countles olber paradox discussions), so i don't think that that would be a good
definition of size.

It wouldn't be accepted by the forest service for determining the size of a
forest, for example. (Can't see the size of the forest for the trees.)

Earl

"GASNER" (Earl Gasner?) replied to George Dishman:

With respect to the "common misconception that the Big Bang occurred
at a point" . . . Yes indeed there is such a misconception of the Big
Bang theory. It is promoted by a significant fraction of 'experts'
who should know better, . . . on Radio, TV and in print. (NOT by you!)
I have heard astronomer/cosmologist after astronomer/cosmologist talk
about the time that the universe was the size of a grapefruit (or
plum, or pomogranite, or whatever).

And all for the want of a single word, "observable". I think
it is said the size of the region we can now observe was the
size of a grapefruit when the era of inflation ended but I
could be wrong.

Well, it 'could' mean how far you can see, but I would consider that
a strange definition of size.

Why? Seems to me like it would be okay.

If our present universe was a few zillion times as dense, then
you couldn't see very far without being obstructed by a star,
(see countles olber paradox discussions), so i don't think that
that would be a good definition of size.

Why not? Why would the limited distance we'd be able to see
in that situation make talking about the size of the observable
universe less meaningful or useful?

It wouldn't be accepted by the forest service for determining the
size of a forest, for example. (Can't see the size of the forest
for the trees.)

The analogy you present is a forest which has no visible far
edge. How would the Forest Service determine the size of a
forest whose far edge cannot ever be seen, even in theory?
Wouldn't it make sense to determine the size of the part of
the forest that *has* been seen, and use that as a measure?

-- Jeff, in Minneapolis

Subtract 1 from my e-mail address above for my actual address.
..

greywolf42 wrote:

CMBR photon directions are 'random' and from 'no definite source.' The
standard theoretical interpretation is fine. But it's still a theory.

Now, can you tell me where those 'old globular clusters' went? Or will you
continue to quibble about my wording of BB age predictions?

Okay, you have been told where to go look to see how the apparent
incompatibility was resolved. You are either too ignorant to go verify it for
yourself or you hold on to a falsehood that preserves your world view.

So, to make it very clear, go visit the Hipparchos web site. It will provide
information of how new measurements of the calibration standards, such as the
Cepheid variables, has reduced the age determined for the globular clusters to a
value within the error bars of the current estimated age of the universe based
on the WMAP data.

The web site: http://astro.estec.esa.nl/Hipparcos/hipparcos.html

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...
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Diagrams in Prof Wright's tutorial show red-shift increasing

But it doesn't get PROGRESSIVELY lower. An increase in the distance to
the train doesn't change the tone

Correct. The note depends on the speed and a constant
speed gives a constant note.
It doesn't matter how many compressions are involved- the frequency
will be the rate at which they strike my ear (events/time)

Right. Now if the source emits at rate 'a' events/second
and a constant number of waves are in transit (zero speed)
then you hear the same rate. If you are walking away from
source, the number in transit is increasing so the rate
you hear must be lower than 'a'. Walk towards the source
and the rate will be higher than 'a' (but still a constant
rate for constant speed).

Right, but during the time you were walking, more waves
must have reached your ear so the note is as emitted
while you stand but must be higher while you are
walking towards the source. Remember the context, I
was trying to show why the note will always be higher
if the distance between you and the sourse is reducing
and lower if it is increasing.

Yes

Amplitude will vary as you say but that's not in dispute
so I haven't mentioned it.

Agreed

The same thing happens if the whistle is moving towards
you, as time goes on, the distance reduces so the number
of waves in transit at any time is reducing. You hear
those extra waves as a higher note.

Are you pulling my chain George? It's a higher note, but will not
alter unless the train alters speed (or I do). You must know this!?

Yes of course, I was showing that you couldn't change
it to be lower instead of higher just by changing the
coordinates you use to describe the effect. Remember you
said: "But if the very distant bodies were designated 0,
then everything closer would have a blue shift." That is
not true, a blue shift occurs when the distance is
reducing. For example the Andromeda Galaxy has a blue
shift because it is moving towards us.

Conversely if the distance between you and the whistle
is increasing, then you hear a lower note. It doesn't
matter what combination of motion is responsible, the
number of waves in transit is (roughly) the distance
between you and the whistle divided by the speed of
sound. If that distance is increasing, the number is
increasing and that makes the note lower.

Your'e having me on!! The VELOCITY has to be changing to change the
note, not the distance.

For a given velocity, you get a given note. If the
velocity changes, the note changes. Zero velocity
means you hear the same note that was emitted. You
say this in your next paragraph.

Once again, the lower (different) note is due to velocity, not
distance.

Right.

If the three trains went by at different intervals, but at
the same speed, some time later they would be at 100, 200, 300 yards,
but each whistle would have the same frequency (and a nice harmonic)

At the same speed, yes. But in the paragraph above the
speed for each train is _different_. I thought you had
picked that up last time.

That has two important effects, first the note from each
train is different (though for each it is constant if
the speed is constant as you said) and secondly the time
since the train passed you is the same for all the trains.

That
is what we see when we look at galaxies, the red-shift
from each galaxy is proportional to its distance (and no,
the distance is not determined from the red-shift).

If you persist with comparing sound to light (which I don't subscribe
to),

There is a slight difference but it is negligible at
the speeds we are dealing with, the first-order effect
predominates and that is the same as sound. We can talk
about it separately if you like.

my arguement above re sound Doppler, rebuts this 'red shift is
due to distance'.

We know from lab experiments that for speeds much less
than the speed of light, red-shift is proportional to
speed. What we find by measurement is that there is a
trend in the red-shift of galaxies, the red-shift is
proportional to distance. We conclude from those two
that there is a trend in the speed of galaxies, that
more distant galaxies are moving away from us at
greater speeds.

Now imagine you had filmed those trains passing through
the station. Play the film backwards and you would find
they all passed you at the same time, about 20 seconds
before the moment I described above. For galaxies it is
more complex because the speed has been changing but the
logical conclusion is the same, they were all close
together some time ago, and it appears that was about
13.7 billion years ago.


Apology if I seemed to have snipped content relevent to discussion.
To summarise:
You maintain that galaxies at different distances have red shift
proportional to their distance from us, compared to lab emmissions.
That the red shift is an indicator of velocity also.
That about 13bya, the (groups) of galaxies were close together (I
understand how galactic and group-galactic rotations could alter the
observed red shifts)

But.... as there must have been a greater accelleration applied to the
further galaxies (they have a higher velocity) if they left BB at same
time??? (At all times thus far in thread I am discussing expanding
from grape fruit scenario)
Your trains went through the station at different speeds, therefore at
some previous time they have been subject to different accellerations.
With BB, if outer galaxies have different speed, and left at same time
(BB), they too had different accel. than closer ones.

Take point 0 as origin, and galaxies A (100 mph indicated red shift) B
(200) C (300) at increasing distance. We are seeing C as it was at
point A (back in time) and it had a higher velocity than A has 'now',
so universe was expanding faster then (right?). But if as claimed, the
universe is homogenous at large scale, A and his mates need to be
going faster than C and his, in order to maintain an even distribution
of matter (4/3 pi r^3). There seems to be conflict between these
positions.

And nobody has given me an inkling as to why space would expand
between groups of galaxies (only?????)

Soldier on
Jim G