"Floyd Baker" wrote in message ...
On Wed, 15 Sep 2004 19:08:52 +0000 (UTC), "Martin Hogbin"
wrote:


"Floyd Baker" wrote in message ...
On Thu, 9 Sep 2004 22:06:18 +0000 (UTC), "Martin Hogbin"
wrote:


I measure the speed of light from a laser to be 300,000 km/s
in a vacuum. I travel in a rocket towards you at 100,000 km/s
you measure the light to pass you at 300,000 km/s. Now I
stand still and you run towards me at 100,000 km/s. You
measure the light to pass you at 300,000 km/s. This is what
really happens.

I see the light similar to sound,

That is how most physicists saw things in about 1900.

It sounds like so far no one has proven them wrong... g

But I'm listening.

The example above proves them wrong. Light does not behave
like sound.


Going by what you say above, apparently light is not affected by the
same rules that sound is.

That is correct.

Well the blue shift happens. Isn't that the doppler effect?

Yes, but the important thing at this stage
is what the speed does.


Visible light is in the same spectrum that subsonic and microwaves
are... It makes no sense that they don't all behave the same...

Light and microwaves are all electromagnetic waves (not
sure what you mean by subsonic here) and they do all
behave in the same way (regarding measured speed).

So
with that in mind, I can see natural limits to speed of *any* part of
the spectrum,

Yes, if you are referring to the electromagnetic (EM) spectrum.

whether it's sound through the seas,

Sound goes _much_ slower and is not relevant here.


RF through earth
bound aether,

What is 'earth bound aether'?


or visable light in empty space.


But I can't see *not*
adding or subtracting one's own speed to that of the wave, to change
the *frequency*, as is done with sound..., and is 'apparently' done
with light.., as indicated by the blue shift, or the red shift in the
other direction.


You need to forget about frequency for the moment, it does
change due to relative motion for both light and sound.


What is the *difference* between light and sound in that respect?

There is a small but important difference between
the Doppler effect in sound and light but I cannot explain
this until you have understood the bit about speed.

Any theory of physics that we come up with must
therefore explain this fact which, on the face of it,
does seem absurd.

This is where some of the crackpots fall down. They
produce diagrams or computer simulations to show
that light cannot possibly be measured to have the
same speed by two relatively moving observers.

IOW, physics is a religion... You need faith? g

No! You need experiments. They are the final arbiter
of truth in physics. It is a prime requirement of any model
you propose that it agrees with experiment. Or to put
it anther way, what things actually do is more important than
what you think they ought to do. There are also things that
are arbitrary and a matter of human choice.

As far as I can see, going on the 'one speed of light for all'
concept, each relative speed has to have its own time frame.

Yes, that is pretty well it.

It
seems obvious this is a fact because the faster ones do take longer to
age than the slower ones, as compared to each other when they come
back together.

So.... why *does* speed affect time?

I will come to that later.


If you want to know what light does the only way is
to make measurements on real light.

Ok I'll buy that. But if the faster moving people who are measuring
the same light as those slower moving people on earth are measuring,
it has to mean that the faster people only think they're faster than
the slower people, but in fact are not. I understand they are just
as 'equal' in their own mind as the earth observers. But still, the
people on earth can verify that as the 'faster' people move through
space, it is at a very much slower speed than what they said they
would be doing, and as *is* being measured on the ship at that moment,
right? Actually too, BOTH the ship and the earth are each moving
slower than they each believe, to a 'totally stationary' viewer out in
space. That one person that is *not* relative, eh? That explanation
makes sense to me. Why do I get the feeling that it doesn't to anyone
else? Or how else to put it a better way...? What *does* happen to
cause it? :-)


Sorry, you lost me there.

I see a single light beam being measured to be the same speed by
different velocity observers, as caused by their own perceived time
frame.

Yes, and their own distance measurement. 'Measured' might be
better than perceived. What other kind of time is there anyway?


I see that their perceived time frame is in fact a real stretching of
time, different for each of them, as shown by the fact they are
younger upon returning from a long trip.

Yes.


Ok so I'm looking at it as though light does not increase in speed,
just that time durations it takes to go by me is either shortened, or
lengthened.

No. Depends what you mean there. If a laser emits a pulse that,
in the reference frame of the laser, is 1 metre long then, if you
run towards the laser, it will be less than one metre long. This
is the Doppler effect. On the other hand, if you measure how
long the start of the pulse takes to pass the length of a metre
rule (which you always have with you) then you will always
measure this to be the same whether you move towards the
laser or not.. This is surprising!

As I did by moving towards the end of the sound
duration. What else is the blue or red shift if not this? A change
in the lights 'frequency' but not speed, right?

Exactly so.

Explain the quandary in my last paragraph and then I'll be with you...

After all, it seems that even infinity can be increased by +1.
Simply *start* with the 1 and then add the rest.

Your mistake is in supposing that the arithmetic process
of adding is the right thing to do. For example if I
run relative to the Earth's surface at 10 m/s and throw
a ball at right angles to my direction of motion at 10 m/s
the speed of the ball over the Earth is not 20 m/s.

That's understandable...

No... Actually even in sound, I did not say that the speed of sound
itself increased. I said the frequency was increased, or that I
shortened the duration of it traveling by me by moving myself..., if
would give the appearance of it moving faster.

If one were to measure the speed of sound as they moved towards its
end, would they see a difference in its speed? They would by
necessity, only see its *media* as it moved in the opposite direction
to their travel. Ergo, no true 'sound' speed increase at all.

If they measured the speed at which a sound pulse passed
them they would measure an increase in speed.

I think I have all the 'perspective' fairly clear in my head, but I'm
still wondering mostly how to tie in the time difference. That which
causes all the various velocity observers to see one single beam of
light traveling at its single max'd speed.

The observations which led to the theory of relativity
cannot be explained in terms of the physics which came
before. You cannot therefore ask what causes the
effects you can only ask what their consequences are.

Even though some are
traveling near the speed of light themselves in the same direction.
Are they measuring the 'medium' too?

No. No one has ever measured a medium for light.

That which, as with sound,
would compensate for any differences in the measurERS speed?

A medium for light has never proved a particularly useful
concept.

Is
there a medium in space that light propagates through, that is part of
all measurements?

The first theory that was in agreement with experiment was
proposed by Lorentz in 1904. He proposed that movement
through the aether (the presumed medium fro light at the time)
caused clocks to slow down and rods to shrink, but he could
give no reason why this happens. The result of this is that it is
impossible to measure or detect motion through the aether
thus making it somewhat redundant.

Martin Hogbin