Re: "How Does Light 'Know' How Fast to Travel?"

faJohn Kennaugh <JKNG@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in
news:6PboZQGjgR3GFwNV@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx:

The first order effect is the same as acoustic Doppler where the source
is always what moves never the observer.


False. Either the source or the observer may be in motion. Doppler depends
on relative velocity of source and observer.

Ride in a car at 60 mph down the highway and have a driver in a stationary
car beside the road blow his horn. You will observe the SAME Doppler effect
shift that you would observe if you were stationary and a car passing at 60
mph blew its horn.

This comes from the fact that
the second postulate is describing exactly what an observer stationary
w.r.t the propagating medium would observe.


You can even ride the wind in a hot air balloon and notice the Doppler
effect as you go by the stationary car.

While the driver in a 2nd stationary car does NOT notice any Doppler effect
from the wind's causing the air to move, you, riding with the air, will
hear the Doppler shift.

The FACT is that there are Doppler shifts when the sound waves enter the
medium and again when the sound waves leave the medium. Those shifts cancel
each other out.

Ah ha, you say, what if the winds were gusty and a gust were blowing where
the source was located but not where the observer was located? A Doppler
shift would still not be noticed because somewhere between the source and
the observer a second Doppler shift would take place.

Motion of the medium, or relative to the medium, if one exists, cancels
out, as far as Doppler shift is concerned.

However, a cross wind will effect the propagation losses and the time the
propagation takes, hence MMX's failure to show motion of the aether was the
death blow for that model.



--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+spr@xxxxxxxxxxxxxxxxxxxx remove ch100-5 to avoid spam trap
.

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