"YBM" wrote in message ...
Dirk Van de moortel a écrit :
The velocity v is measured negative downward, moron.
Shouldn't you first tackle the physics they teach to 12 years
old kids, imbecile?

This is Androcles' syndrome #213 : "-x is always negative because their
is a minus signe in front of x".

Yes indeed, a true classic :-)

Dirk Vdm

On Mar 16, 1:25 pm, Tom Roberts wrote:
[...]

Well, sort of. Remember that in SR the constancy of c holds only in
inertial frames, and the elevator is not inertial. In this case, an
INERTIAL observer outside the elevator would measure c for the speed of
the light inside the elevator, but an accelerated observer inside the
elevator would not. Indeed, it is this fact that permits one to compute
the blueshift.

Where do you find anything in SR about "INERTIAL" frames
after P. Langevin in 1918 points out the absurdity of
"time dilation"?

"The [ ] Incompatibility of the Law of Propagation of
Light with the Principle of Relativity [is only] Apparent"
http://www.bartleby.com/173/7.html

"On the interpretation of the redshift in a static gravitational
field"
http://adsabs.harvard.edu/abs/2000AmJPh..68..115O


A Lorentz transformation or any other coordinate
transformation will convert electric or magnetic
fields into mixtures of electric and magnetic fields,
but no transformation mixes them with the
gravitational field.
http://www.aip.org/pt/vol-58/iss-11/p31.html
http://en.wikipedia.org/wiki/Gauge_fixing
http://arxiv.org/abs/physics/0204034

Sue...

[...]

Tom Roberts

On Mar 17, 6:20 am, wrote:
On Mar 17, 1:37 pm, "Eric Gisse" wrote:



wrote:
On Mar 16, 6:25 pm, Tom Roberts wrote:
wrote:
For the elevator at rest on Earth, the blue shift is ~ gh/c^2, where
g is ~ 9.8 m/s^2 and h is the distance top-bottom.

You are claiming that the wavelength are also shifted in the case
of the accelerated elevator, because when the light was emitted
at the ceiling, the floor had a smaller velocity than when the light
was received. Indeed, the craft is accelerating and therefore the
floor changed its velocity during the time of flight of the light.

Correct (velocities measured wrt some appropriate inertial frame).

You are in fact implying that the velocity of light is *not*
independent
of the motion of its source or of the motion of the observer!

Well, sort of. Remember that in SR the constancy of c holds only in
inertial frames, and the elevator is not inertial. In this case, an
INERTIAL observer outside the elevator would measure c for the speed of
the light inside the elevator, but an accelerated observer inside the
elevator would not. Indeed, it is this fact that permits one to compute
the blueshift.

And what is the formula for your alledged shift?

~ gh/c^2 of course (using the same approximation you used above).

How did you derive that formula? The Polasek way is wrong, because it
is based on T = h/c, whereas the light signal travelled a distance
h.

Why are you asking him? It isn't his formula - it is yours.

The question to be asked is why did you use it if you don't understand
it?

Can't you read?

I said:

"For the elevator *at rest* on Earth, the blue shift is ~ gh/c^2,
where g is ~ 9.8 m/s^2 and h is the distance top-bottom."

And I clearly asked for the derivation of the formula giving the shift
for the accelerating elevator.

The formula is the same.

Remember the equivalence principle?


Marcel Luttgens



Marcel Luttgens

Tom Roberts

On Mar 16, 6:25 pm, Tom Roberts wrote:
wrote:
For the elevator at rest on Earth, the blue shift is ~ gh/c^2, where
g is ~ 9.8 m/s^2 and h is the distance top-bottom.

You are claiming that the wavelength are also shifted in the case
of the accelerated elevator, because when the light was emitted
at the ceiling, the floor had a smaller velocity than when the light
was received. Indeed, the craft is accelerating and therefore the
floor changed its velocity during the time of flight of the light.

Correct (velocities measured wrt some appropriate inertial frame).

You are in fact implying that the velocity of light is *not*
independent
of the motion of its source or of the motion of the observer!

Well, sort of. Remember that in SR the constancy of c holds only in
inertial frames, and the elevator is not inertial. In this case, an
INERTIAL observer outside the elevator would measure c for the speed of
the light inside the elevator, but an accelerated observer inside the
elevator would not. Indeed, it is this fact that permits one to compute
the blueshift.

And what is the formula for your alledged shift?

~ gh/c^2 of course (using the same approximation you used above).

Tom Roberts

Hereafter is an analysis of Einstein's elevator
thought experiment, that takes into account the
input of some participants.

Notice that one cannot use the classical Doppler
formula, which is only valid for constant
velocities.


Excerpt from Strobel's Astronomy Notes.
http://www.astronomynotes.com/relativity/s3.htm


"Part of Einstein's genius was his ability
to look at ordinary things from a whole new
perspective and logically follow through on the
consequence of the insights he gained from
his new perspective.

He proposed an experiment involving
two elevators:

one at rest on the ground on the Earth
and another, far out in space away from
any planet, moon, or star, accelerating
upward with an acceleration equal to that
of one Earth gravity (9.8 meters/second2).
(Modern readers can substitute ``rocket ship''
for Einstein's elevator.)

If a ball is dropped in the elevator
at rest on the Earth, it will accelerate
toward the floor with an acceleration of
9.8 meters/second2.
A ball released in the upward accelerating
elevator far out in space will also accelerate
toward the floor at 9.8 meters/second2.

The two elevator experiments get the same
result!"

Discussion:

When photons emitted from the top of the elevator
are measured at the bottom, their wavelengths are
blue-shifted by ~ gh/c^2, where g is ~ 9.81 m/s^2
and h is the distance top-bottom when the elevator is
at rest on the Earth (cf. the Pound-Rebka experiment),
wheras their wavelengths are shifted by a different
amount when the elevator is far out in space away
from any planet, moon, or star, but accelerating
upward with an acceleration equal to that of one
Earth gravity.

Indeed, after the pulse is emitted, the floor
of the accelerating elevator moves upward, hence
the pulse will hit the floor after a time t h/c.

After such time t, the light pulse will be at a
distance d1 = ct from the ceiling, and the floor
will have travelled upward a distance d2= 1/2 gt^2.
From d1 + d2 = h, or ct + 1/2 gt^2 = h, one
gets t = [-c +/- sqrt(c^2 + 2gh)] / g, which is the
time at which the pulse meets the floor.
After that time t, the velocity of the floor is
v = gt = -c + sqrt(c^2 + 2gh), hence the shift
will be v/c = -1 + sqrt(1 +/- 2gh/c^2), or
approximately (when g and/or h are small),
v/c = -1 + 1 -/+ gh/c^2 = -/+ gh/c^2.
The value of the calculated blue shift,
i.e. gh/c^2, is thus almost identical, but *not
equal*, to the the shift obtained for the elevator
at rest on Earth.

Conclusively, the two elevator experiments only
get approximately the same result when the
acceleration of gravity and/or the height of the
elevator are very small.

Marcel Luttgens

On Mar 16, 5:41 am, wrote:
On 16 mar, 07:05, wrote:





Excerpt from Strobel's Astronomy Notes.http://www.astronomynotes.com/relativity/s3.htm

"Part of Einstein's genius was his ability to look at ordinary things
from a whole new perspective and logically follow through on the
consequence of the insights he gained from his new perspective.

He proposed an experiment involving two elevators:

one at rest on the ground on the Earth and another, far out in space
away from any planet, moon, or star, accelerating upward with an
acceleration equal to that of one Earth gravity (9.8 meters/second2).
(Modern readers can substitute ``rocket ship'' for Einstein's
elevator.)

If a ball is dropped in the elevator at rest on the Earth, it will
accelerate toward the floor with an acceleration of 9.8 meters/
second2.
A ball released in the upward accelerating elevator far out in space
will also accelerate toward the floor at 9.8 meters/second2.

The two elevator experiments get the same result!"

Einstein was wrong:

The two elevator experiments don't get the same result!

When photons emitted from the top of the elevator are measured
at the bottom, their wavelengths are blue-shifted when the elevator is
at rest on the Earth (cf. the Pound-Rebka experiment), wheras their
wavelengths are not shifted at all when the elevator is far out
in space away from any planet, moon, or star, but accelerating upward
with an acceleration equal to that of one Earth gravity.

Marcel Luttgens

I think you forgot to take into account the Doppler effect. In the
space inertial frame where the light is emitted at the top, the
receptor at the botton receives the light at a some higher velocity
than the emitter one, producing the same blue-shift than in Earth.

RVHG- Hide quoted text -

- Show quoted text -

Hmmm

"Top" and "bottom" of the elevator move at the SAME speed (if you
consider the elevator to be Born-rigid).
This meas that source and emitter move at the SAME speed.
This means NO Doppler effect.
This means your explanation does not hold.

On 18 Mar 2007 08:25:37 -0700, wrote:

On Mar 16, 5:41 am, wrote:
On 16 mar, 07:05, wrote:





Excerpt from Strobel's Astronomy Notes.http://www.astronomynotes.com/relativity/s3.htm

"Part of Einstein's genius was his ability to look at ordinary things
from a whole new perspective and logically follow through on the
consequence of the insights he gained from his new perspective.

He proposed an experiment involving two elevators:

one at rest on the ground on the Earth and another, far out in space
away from any planet, moon, or star, accelerating upward with an
acceleration equal to that of one Earth gravity (9.8 meters/second2).
(Modern readers can substitute ``rocket ship'' for Einstein's
elevator.)

If a ball is dropped in the elevator at rest on the Earth, it will
accelerate toward the floor with an acceleration of 9.8 meters/
second2.
A ball released in the upward accelerating elevator far out in space
will also accelerate toward the floor at 9.8 meters/second2.

The two elevator experiments get the same result!"

Einstein was wrong:

The two elevator experiments don't get the same result!

When photons emitted from the top of the elevator are measured
at the bottom, their wavelengths are blue-shifted when the elevator is
at rest on the Earth (cf. the Pound-Rebka experiment), wheras their
wavelengths are not shifted at all when the elevator is far out
in space away from any planet, moon, or star, but accelerating upward
with an acceleration equal to that of one Earth gravity.

Marcel Luttgens

I think you forgot to take into account the Doppler effect. In the
space inertial frame where the light is emitted at the top, the
receptor at the botton receives the light at a some higher velocity
than the emitter one, producing the same blue-shift than in Earth.

RVHG- Hide quoted text -

- Show quoted text -

Hmmm

"Top" and "bottom" of the elevator move at the SAME speed (if you
consider the elevator to be Born-rigid).
This meas that source and emitter move at the SAME speed.
This means NO Doppler effect.
This means your explanation does not hold.

Not really.
They are both moving up at speed V when the light pulses, but the
bottom is moving up when the pulse gets there at V + gT = V +gh'/c.
where h' = h - gt^2/2 = h - gh^2/2c^2.
John Polasek

On Mar 18, 1:04 pm, John C. Polasek wrote:
On 18 Mar 2007 08:25:37 -0700, wrote:



On Mar 16, 5:41 am, wrote:
On 16 mar, 07:05, wrote:

Excerpt from Strobel's Astronomy Notes.http://www.astronomynotes.com/relativity/s3.htm

"Part of Einstein's genius was his ability to look at ordinary things
from a whole new perspective and logically follow through on the
consequence of the insights he gained from his new perspective.

He proposed an experiment involving two elevators:

one at rest on the ground on the Earth and another, far out in space
away from any planet, moon, or star, accelerating upward with an
acceleration equal to that of one Earth gravity (9.8 meters/second2).
(Modern readers can substitute ``rocket ship'' for Einstein's
elevator.)

If a ball is dropped in the elevator at rest on the Earth, it will
accelerate toward the floor with an acceleration of 9.8 meters/
second2.
A ball released in the upward accelerating elevator far out in space
will also accelerate toward the floor at 9.8 meters/second2.

The two elevator experiments get the same result!"

Einstein was wrong:

The two elevator experiments don't get the same result!

When photons emitted from the top of the elevator are measured
at the bottom, their wavelengths are blue-shifted when the elevator is
at rest on the Earth (cf. the Pound-Rebka experiment), wheras their
wavelengths are not shifted at all when the elevator is far out
in space away from any planet, moon, or star, but accelerating upward
with an acceleration equal to that of one Earth gravity.

Marcel Luttgens

I think you forgot to take into account the Doppler effect. In the
space inertial frame where the light is emitted at the top, the
receptor at the botton receives the light at a some higher velocity
than the emitter one, producing the same blue-shift than in Earth.

RVHG- Hide quoted text -

- Show quoted text -

Hmmm

"Top" and "bottom" of the elevator move at the SAME speed (if you
consider the elevator to be Born-rigid).
This meas that source and emitter move at the SAME speed.
This means NO Doppler effect.
This means your explanation does not hold.

Not really.
They are both moving up at speed V when the light pulses, but the
bottom is moving up when the pulse gets there at V + gT = V +gh'/c.
where h' = h - gt^2/2 = h - gh^2/2c^2.
John Polasek



Nonsense, both the emitter and the receiver move with the same speed ,
so there can be no Doppler effect.

wrote in message oups.com...
On Mar 18, 1:04 pm, John C. Polasek wrote:
On 18 Mar 2007 08:25:37 -0700, wrote:



On Mar 16, 5:41 am, wrote:
On 16 mar, 07:05, wrote:

Excerpt from Strobel's Astronomy Notes.http://www.astronomynotes.com/relativity/s3.htm

"Part of Einstein's genius was his ability to look at ordinary things
from a whole new perspective and logically follow through on the
consequence of the insights he gained from his new perspective.

He proposed an experiment involving two elevators:

one at rest on the ground on the Earth and another, far out in space
away from any planet, moon, or star, accelerating upward with an
acceleration equal to that of one Earth gravity (9.8 meters/second2).
(Modern readers can substitute ``rocket ship'' for Einstein's
elevator.)

If a ball is dropped in the elevator at rest on the Earth, it will
accelerate toward the floor with an acceleration of 9.8 meters/
second2.
A ball released in the upward accelerating elevator far out in space
will also accelerate toward the floor at 9.8 meters/second2.

The two elevator experiments get the same result!"

Einstein was wrong:

The two elevator experiments don't get the same result!

When photons emitted from the top of the elevator are measured
at the bottom, their wavelengths are blue-shifted when the elevator is
at rest on the Earth (cf. the Pound-Rebka experiment), wheras their
wavelengths are not shifted at all when the elevator is far out
in space away from any planet, moon, or star, but accelerating upward
with an acceleration equal to that of one Earth gravity.

Marcel Luttgens

I think you forgot to take into account the Doppler effect. In the
space inertial frame where the light is emitted at the top, the
receptor at the botton receives the light at a some higher velocity
than the emitter one, producing the same blue-shift than in Earth.

RVHG- Hide quoted text -

- Show quoted text -

Hmmm

"Top" and "bottom" of the elevator move at the SAME speed (if you
consider the elevator to be Born-rigid).
This meas that source and emitter move at the SAME speed.
This means NO Doppler effect.
This means your explanation does not hold.

Not really.
They are both moving up at speed V when the light pulses, but the
bottom is moving up when the pulse gets there at V + gT = V +gh'/c.
where h' = h - gt^2/2 = h - gh^2/2c^2.
John Polasek



Nonsense, both the emitter and the receiver move with the same speed ,

But after the emitter emitted, it takes some time before the
receiver receives. During that time the receiver has increased
his speed w.r.t. the instantaneous inertial frame he was in when
the emitter emitted,

so there can be no Doppler effect.

so there is a Doppler effect :-)

Dirk Vdm

On Mar 18, 7:15 am, wrote:

[...]

Conclusively, the two elevator experiments only
get approximately the same result when the
acceleration of gravity and/or the height of the
elevator are very small.

.....and Marcel rediscovers the concepts of "locally true" and
"approximation".


Marcel Luttgens

On Mar 18, 3:33 pm, "Dirk Van de moortel" dirkvandemoor...@ThankS-NO-
SperM.hotmail.com wrote:
wrote in ooglegroups.com...
On Mar 18, 1:04 pm, John C. Polasek wrote:
On 18 Mar 2007 08:25:37 -0700, wrote:

On Mar 16, 5:41 am, wrote:
On 16 mar, 07:05, wrote:

Excerpt from Strobel's Astronomy Notes.http://www.astronomynotes.com/relativity/s3.htm

"Part of Einstein's genius was his ability to look at ordinary things
from a whole new perspective and logically follow through on the
consequence of the insights he gained from his new perspective.

He proposed an experiment involving two elevators:

one at rest on the ground on the Earth and another, far out in space
away from any planet, moon, or star, accelerating upward with an
acceleration equal to that of one Earth gravity (9.8 meters/second2).
(Modern readers can substitute ``rocket ship'' for Einstein's
elevator.)

If a ball is dropped in the elevator at rest on the Earth, it will
accelerate toward the floor with an acceleration of 9.8 meters/
second2.
A ball released in the upward accelerating elevator far out in space
will also accelerate toward the floor at 9.8 meters/second2.

The two elevator experiments get the same result!"

Einstein was wrong:

The two elevator experiments don't get the same result!

When photons emitted from the top of the elevator are measured
at the bottom, their wavelengths are blue-shifted when the elevator is
at rest on the Earth (cf. the Pound-Rebka experiment), wheras their
wavelengths are not shifted at all when the elevator is far out
in space away from any planet, moon, or star, but accelerating upward
with an acceleration equal to that of one Earth gravity.

Marcel Luttgens

I think you forgot to take into account the Doppler effect. In the
space inertial frame where the light is emitted at the top, the
receptor at the botton receives the light at a some higher velocity
than the emitter one, producing the same blue-shift than in Earth.

RVHG- Hide quoted text -

- Show quoted text -

Hmmm

"Top" and "bottom" of the elevator move at the SAME speed (if you
consider the elevator to be Born-rigid).
This meas that source and emitter move at the SAME speed.
This means NO Doppler effect.
This means your explanation does not hold.

Not really.
They are both moving up at speed V when the light pulses, but the
bottom is moving up when the pulse gets there at V + gT = V +gh'/c.
where h' = h - gt^2/2 = h - gh^2/2c^2.
John Polasek

Nonsense, both the emitter and the receiver move with the same speed ,

But after the emitter emitted, it takes some time before the
receiver receives. During that time the receiver has increased
his speed w.r.t. the instantaneous inertial frame he was in when
the emitter emitted,

so there can be no Doppler effect.

so there is a Doppler effect :-)

Dirk Vdm



Hmmm,

You must have come up with an extension to the equations of the
Doppler effect . The Doppler equations is derived for uniform motion,
how do you generalize to accelerated motion? You can't use the
equations of the classical Doppler effect as you have done earlier in
this thread, you need to derive the equations from base principles.
Can you show how this can be done? I am not challenging, I am just
interested.