Re: What is Proper Time?
- From: The Ghost In The Machine <ewill@xxxxxxxxxxxxxxxxxxxxxxx>
- Date: Sun, 16 Mar 2008 21:10:32 -0700
In sci.physics.relativity, HW@....(Dr. Henri Wilson)
<HW@>
wrote
on Sun, 16 Mar 2008 21:16:57 GMT
<2u2rt3dnisbima2ad05mudmuohkoita1sq@xxxxxxx>:
On Tue, 11 Mar 2008 22:24:34 -0700, The Ghost In The Machine
<ewill@xxxxxxxxxxxxxxxxxxxxxxx> wrote:
In sci.physics.relativity, HW@....(Dr. Henri Wilson)
<HW@>
wrote
Light from the source is directed towards the mirror on the spinning wheel.
The peripheral speed is 2.1E-7c, as you stated.
Light hits the mirror at (1+2.1E-7)c wrt the mirror. It reflects from the
mirror at the same (1+2.1E-7)c wrt the mirror...which is (1+4.2E-7)c wrt the
Source/observer.
get it now?
Hmm...yes. OK, revision of the table.
lambda/lambda_0 nu/nu_0 c/c_0
nBAT: 1 1 - 4.2 * 10^-7 1 - 4.2 * 10^-7
Bath: 1 1 - 4.2 * 10^-7 1 - 4.2 * 10^-7
SR: 1 + 4.2 * 10^-7 1 - 4.2 * 10^-7 1
Androcles: 1 - 4.2 * 10^-7 1 1 - 4.2 * 10^-7
(values are approximate)
Of course, this is only because the light is reflecting.
Since BaTH is clearly distance-dependent from your statements,
I can't say it's equal to anything.
Ghost, BaTh is quite simple.
Doppler shift is relative speed dependent.
Correct; always has been, though one might quibble as to
whether we're discussing frequency ratio or wavelength
ratio.
According to BaTh, doppler shift relates to the rate at which 'wavecrests'
arrive. So it represents a frequency change.
Wavelength is absolute....but it changes if/when a photon changes speed.
Um...can't have it both ways.
When light enters a medium such as glass, its speed decreases but the number of
wavecrests passing a particular point PER SECOND is the same as it was outside
the glass. Inside the glass, the wavelength decreases.
So we DO have it both ways....
I'm more interested in free space, than in refractive issues. In
particular, a star is moving away from the Earth at speed v; the
wavecrests relative to the star therefore move at speed c-v near the
star (as measured from Earth, presumably, were it possible to hang a
probe motionless with respect thereto near the star). Does light:
[a] slow down?
[b] speed up?
[c] otherwise change characteristics?
(In SR this is not a problem; the lightspeed is c everywhere, and there's
no absolute time or space.)
If the star is instead moving towards Earth, one can ask the same
questions.
SR has both; Androcles' variant changes wavelength only;
standard Newtonian changes frequency only.
Androcles thinks an oscillator, such as a spinning wheel or pendulum, possesses
some kind of natural wavelength.
He is correct to a point; all oscillators possess a natural frequency.
Can't you read Ghost....or are you as bad as Androcles.
I SAID "IT DOESN'T POSSESS A NATURAL WAVELENGTH".
All oscillators possess a natural frequency. If there's
a natural speed one thereby derives a natural wavelength,
relative to the oscillator anyway.
In the case of a radio wave, that natural speed is c_0. One
can either explain away c_0 as an intrinsic property, or
relate it to two or more other properties (permittivity and
permeability, for example).
It doesn't It possesses a frequency.
In such cases, 'wavelength' is a manmade and frame dependent quantity defined
as the distance the oscillator moves in one of its cycles.
The oscillator is not moving; it is radiating.
A pendulum doesn't radiate much...nor does a spinning flywheel.
Depends. An LC tank circuit radiates to some extent
(although an antenna helps). Such a circuit has a natural
frequency and a natural wavelength.
by contrast, a traveling wave, such as on a water surface DOES possess an
absolute, ie., FRAME INDEPENDENT wavelength.
It's easy to prove with nBat anyway. Take frame O, and three events
(0,0) -> (0,0) (start of wave 0)
(c_0,1) -> (c_0 - v, 1) (start of wave 0 after 1 second)
(0,1) -> (-v , 1) (start of wave 1 after 1 second)
Clearly, the wavelength -- the difference between X coordinates
in the last two points above -- is still c_0 in both frames.
Just use the traveling wave equation: A= Ao.sin(t/T-x/Lambda)
Since I'm not familiar with that equation, you'll have to bear with me.
For its part SR sees the world a little differently:
(0,0) -> (0,0)
(c_0,1) -> (g(c_0 - v), g(1 - v/c_0))
(0,1) -> (-gv, g)
which means we need to add another event somewhere; the wavelength
can't be subtracted from points 2 and 3 as they're not at the same
time in the observer's frame. The simplest one would be
(c_0/(1 - v/c_0), 1/(1 - v/c_0)) -> (gc_0, g)
which gives us a wavelength of g(c_0 + v)
= c_0 * sqrt(1+v/c)/sqrt(1-v/c).
...but we know SR is nonsense....
Correct. The odd thing about SR is that it tends to predict things
correctly, though.
If a wave changes speed over distance, either the wavelength or the
frequency or both have to change.
Yes Ghost....but it depends entirely on what kind of wave one is talking about.
There are only two types of wave: transverse and longitudinal. Sound is
the latter; light is a combination of two of the former (E and M
vectors, as Sue will readily tell you ;-) ).
NO! Light is like neither. Sue is an aetherist.
Light is particulate. The particles are oscillating intrinsically.
Which way are they oscillating?
If one vibrates a medium with a frequency f, and the velocity of the
wave in that medium is v, what is the wavelength? Simple:
w = v * t, where t = 1/f, as frequency is specified in Hz, the
reciprocal of seconds. For example, standard power in the US is
at 60 Hz -- 60 cycles per second.
If v changes, of course, one or both of w or f has to change.
F has not changed. Obviously wavelength does...if the wires are long enough.
So you agree with Androcles then? Interesting.
You can easily work out the wavelength Ghost.
3E8/60 metres. ..or v/60
Not quite that simple. For starters, c != c_0. Androcles'
theory (or, more precisely, the "natural theory" to which
he subscribes) is very clear on that point; if a source is
in motion with respect to an observer, the observer's light
speed is c - v, and the observer sees a wavelength shift.
(Newton predicts a frequency shift. SR predicts both.)
The frequency doesn't change because that is the speed of the generator.
A corollary, of course, is that, since w = v/f, v = w * f. This
corollary can be used and has been used to measure lightspeed.
Ghost, light is not a 'wave in a medium'. It is particulate.
So how come window screens, among other things, get diffraction effects?
Each 'particle' has an intrinsic 'wavelength'...and diffracts.
OK.
Light moves at c in both directions.
Travel time is D/c in both directions.
Androcles is very confused.
But Androcles is also correct! Light from A-B-A does
not have to travel such that t(A-B) = t(B-A). This is
routinely observed when an airplane meets a head- or
tailwind, and is known (AFAIK, anyway) as the "headwind
problem". Another variant is a canoe traveling between two
buoys stuck in a river.
Ghost, Einstein's statement refers to the specific situation in which A and B
are separated by 'd'. A sends a pulse of light to B. Its travel time, tAB. B
sends a pulse towards A. Its travel time, tBA. Acording to BaTh, both tAB and
tBA = d/c.
And according to Androcles, tAB != tBA.
Androcles is talking about a pair of observers that are separated by a fixed
distance and moving wrt the source. This is similar to the 'aether' situation.
Einstein's clock synch definition was a devious trick to get rid of the aether.
But the irony is that what he did happened to be correct according to BaTh.
Einstein is not and cannot be correct. After all, SR is
an aether theory (according to Androcles).
The devious Einstein, who must have suspected that light was really ballistic,
managed to find a way to render the traditional aether redundant by adjusting
his clocks (which may others still believed were moving through the absolute
aether) so that tAB always = tBA.
Of course it depends on the theory one is using; SR makes
the explicit assumption that t(A-B) = t(B-A). This is
Einstein's implied Third Postulate, and is not unreasonable
but is hard to verify directly.
SR does NOT make that assumption. SR adjusts A's and B's clocks so that it
happens.
Oh, yes SR does make that assumption. One can either explicitly make
it, as Androcles does (not unreasonable, but he then immmediately
rejects it, which leads to some strange conclusions), or subsume the
assumption in the assumption that all observers use the same "laws" of
physics.
In actual fact......because light is ballistic.... the clocks do NOT have to be
adjusted at all.
The clocks don't have to be adjusted anyway; one merely
needs to subtract.
Ghost, according to classical aether theory (and Androcles) tAB is generally
not equal to tBA.
Einstein got around this by adjusting his clocks so that tAB DOES equal tBA.
So how does one have tAB != tBA but still see no wavelength shift in MMX?
According to BaTh, tAB = tBA, something that is verified in every decent TWLS
experiment.
A straight TWLS cannot verify that at all. A rotating one
(e.g., MMX) might if the measurements are done while the
experiment is at rest (the rotation being done between
measurements).
What the hell are you talking about, Ghost?
TWLS experiment are normally linear although they can be done in a bent fibre
cable.
A straight TWLS experiment has exactly one clock.
That clock measures tAB + tBA. No way to ascertain what
tAB or tBA are, relative to that sum.
Doing measurements while the experiment
is rotating gets one into Sagnac territory, which *does*
disprove SR in a way as it defines a non-inertial reference
frame, where SR doesn't quite operate. (Approximations,
however, are possible, much like approximating a parabola
with a series of successively smaller rectangles.)
Now you are in nonsense territory.
Perhaps. But Sagnac does disprove SR according to Androcles.
Me, I subscribe that Sagnac is *outside* SR, though SR can be stretched
to include it.
For its part nBat cannot reproduce the Sagnac results.
Henri Wilson. ASTC,BSc,DSc(T)
www.users.bigpond.com/hewn/index.htm
....specialising in teaching physics to engineers and mathematicians....
--
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Windows just messes with one's head.
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