Re: What is Proper Time?
- From: The Ghost In The Machine <ewill@xxxxxxxxxxxxxxxxxxxxxxx>
- Date: Tue, 11 Mar 2008 22:24:34 -0700
In sci.physics.relativity, HW@....(Dr. Henri Wilson)
<HW@>
wrote
on Mon, 10 Mar 2008 22:30:10 GMT
<95bbt356spsvj7b36ooafftmstoq1ou3v9@xxxxxxx>:
On Sun, 9 Mar 2008 20:59:27 -0700, The Ghost In The Machine
<ewill@xxxxxxxxxxxxxxxxxxxxxxx> wrote:
In sci.physics.relativity, HW@....(Dr. Henri Wilson)
<HW@>
wrote
on Sun, 09 Mar 2008 21:29:28 GMT
<gpk8t3lg0akfigbrgo54ptls9dith43aq0@xxxxxxx>:
On Sat, 8 Mar 2008 16:48:26 -0800, The Ghost In The Machine
<ewill@xxxxxxxxxxxxxxxxxxxxxxx> wrote:
In sci.physics.relativity, HW@....(Dr. Henri Wilson)
<HW@>
wrote
on Sat, 08 Mar 2008 22:58:20 GMT
Even if the source was moving it would make no difference.
It would simply mean that the light speed around the apparatus was c+v instead
of c.
If one uses a spinning device to feed the MMX, of sizeShouldn't you double the value?
about 10cm in diameter and running at 12,000 RPM, the edge
speed is about 63 m/s, or 2.1 * 10^-7 c. Bouncing light
off this device (assuming the edge is rotating in the
opposite direction of the beam, in an attempt to slow it
down) should result in something like the following:
lambda/lambda_0[*] nu/nu_0 c/c_0
nBAT: 1 1 - 2.1 * 10^-7 1 - 2.1 * 10^-7
SR: 1 + 2.1 * 10^-7 1 - 2.1 * 10^-7 1
Androcles: 1 - 2.1 * 10^-7 1 1 - 2.1 * 10^-7
BaTH: ? ? ?
Nope. Mathematically, v = lambda * frequency.
S--------->c-------------------------M<-2.1E-7c
O-------------<4.2E-7c------------M<-2.1E-7c
speeds are shown relative to S/O.
Could you clarify this diagram, please? What do these values relate to?
It describes YOUR above experiment. I gather you found it in a book and didn't
actually understand it. The observer and source are together so only one clock
is required.
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.
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.
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.
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.
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).
It is not distance dependent, except in so far as light speed might change over
distance.
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 ;-) ).
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.
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?
My model (which seems to work) likens a photon to a 'serated bullet' where the
serations are actually formed by some kind of INTRINSIC wave motion running
along a package of 'the stuff that fields are made of'. You might say that a
photon carries along with itself, its own little bit of personal aether in
which the oscillations take place.
His animation uses a source 'at rest' and two observers moving in oppposite
directions. Naturally, they measure different times for light to travel the
same distacne.
As they should, if the observers are moving at different speeds.
That's right. But that's not what Einstein's clock synching was all about.
His mirror/observer was at rest wrt the source/observer.
Doesn't have to be.
A------->c------------------------c<-------B
A and B are mutually at rest.
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.
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.
According to BaTh, tAB = tBA, something that is verified in every decent TWLS
experiment.
A straight TWLS cannot verify that at all. A rotating TWLS
(e.g., MMX) might if the measurements are done while the
experiment is at rest (the rotation being done between
measurements). 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.)
Henri Wilson. ASTC,BSc,DSc(T)
www.users.bigpond.com/hewn/index.htm
....forever teaching physics to engineers....
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