Re: time dilation


"rbwinn" <rbwinn3@xxxxxxxx> wrote in message
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On Apr 14, 1:08?am, "harry" <harald.vanlintelButNotT...@xxxxxxx> wrote:
"rbwinn" <rbwi...@xxxxxxxx> wrote in message

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On Apr 11, 10:19?am, "harry" <harald.vanlintelButNotT...@xxxxxxx>
wrote:





"rbwinn" <rbwi...@xxxxxxxx> wrote in message

If a weight is dropped from the top of a
train car to the floor, it falls a distance of y'. ?In any
transformation equations this is always expressed as y'=y. ? The
object travels the same distance vertically in S' as it does in S.
In Galileo's equations, it takes the same amount of time for the
object to travel from the roof of the train car to the floor in
either
frame of reference. ?t'=t.
? ? In the Lorentz equations, a clock in S', the frame of reference
of the train car, is slower than a clock in S, the frame of
reference
of the train tracks.
t'=(t-vx/c^)/sqrt(1-v2/c^2). ?According to this equation, it takes
less time for the object to fall from the roof of the train car to
the
floor in S' than it does in S. ?So how are the laws of physics the
same in both frames of reference?
? ? ?If a clock in S ticks once while an object is falling in the
train car, it will not tick in S' until after the object has hit
the
floor. ?This means that the object is falling with a faster
velocity
in S' than in S.
? ? ?I am sure that some of our scientific friends who believe in a
distance contraction will be anxious to explain this phenomenon.
Robert B. Winn

Neat. :-)
First a precision: as measured in all inertial frames, processes of
completely moving systems appear to be slower by the Lorentz factor.
However, your falling weight process is about a mixed system - thus
(as
Einstein also briefly pointed out in 1905) your train better not use
pendulum clocks. ;-)

: Well, I don't need to use pendulum clocks. ?I can use two weights as
: clocks.

That's exactly what I meant that you should not do, as I just explained
to
you, one century after Einstein explained it to his readers. :-)
If you use balance clocks (or better quartz clocks, or even better,
atomic
clocks) - that's OK.

: Well, Darwin and I have resolved this.

Who is Darwin?

: We are using cesium clocks as weights.

Oh that's what you meant! You unnecessarily complicate matters with
falling
clocks - keeping clocks on the floor where the weights will hit makes the
description less complicated - and less expensive, you don't want to
break
those clocks for no reason! :-)

: Now according to scientists, the last picture will show the
: clocks hitting the floor with the clock on the train showing less time
: than the clock in S if the picture is taken from S, and with less time
: on the clock in S if the picture is taken from S'.

According to scientists the event of an object (or objects) hitting the
floor in close proximity of a clock (or clocks) can not be different in
different frames - thus your assertion is wrong. A picture of the weights
hitting the floor at one location will be the same, independent of the
motion of the camera (apart of motion blurr of course).

: ? ? ?At any rate I do not have the same problem you have because I use
: the Galilean transformation equations. ?t'=t. ?The two clocks will hit
: the floor at the same time from either frame of reference, regardless
: of what time the clocks show.

Before complicating matters with falling objects, you would do better to
try
to understand just two relatively moving reference frames with clocks
that
are fixed on them: apparently you think that according to SRT there is
disagreement about the indications on two clocks when they pass each
other.
Not so!

: If we put an identical train car beside the track and take
: pictures of two weights as they fall in the two train cars, according
: to experiment, the two weights will strike the floors of the train
: cars at the same time as photographed from either frame of reference
: if they are released at the tops of the train cars at the same time.
: This is not some imaginary experiment. ?It has been done numerous
: times. ?According to photographs, the two weights fall at the same
: rate and strike the floors at the same time.

If you mean that the other car is not moving: I doubt that your claim
corresponds to GRT. Has that been tested with sufficient precision to
enable
comparing GRT with Galileo? I don't think so.

: Ok, so you are saying that GRT predicts that one weight strikes the
: floor before the other.

I suspect so. You are making claims about predictions and tests, and it
appears you are making them up while you write.

: Which weight strikes the floor first, and
: what does that do to the principle of equivalence?
: We seem to be right back where scientists were before Galileo dropped
: the two weights from the top of the leaning tower of Pisa.

Remember, you are making the claims - just prove them. :-)
In order to work out such GRT problems (which probably are not needed for
your issues), you may need to look into how the Machian principle is
integrated in GRT. The principle of equivalence has limited use but it
does
work for two weights that are dropped from the tower of Pisa.

Harald- Hide quoted text -

- Show quoted text -

Darwin 123 is a scientist who responded to my post. He had the idea
of dropping two clocks. I really like this idea because it shows the
basic difference between the ideas of scientists and my own ideas.
The scientific interpretation is that the picture taken from S will
show the S clock hitting the floor and the S' clock still in the air
showing less time than the S clock. The picture taken from S' will
show the S' clock hitting the floor and the S clock still in the air
showing less time than the S' clock.

No. Due to the limited speed of light and the conventionality of one-way
lightspeed, a picture taken of two objects with one object far behind the
other such as in your example cannot really show what happened when - as
people became aware of by the end of the 19th century - this became known as
"local time" and "relativity of simultaneity". Such pictures can only "show"
it by convention; that is, by assuming that the speed of light is isotropic
in their frame of choice. In other words, such pictures themselves only show
that the sequence depends on one's assumptions/choice of reference frame.
See also Wikipedia: "Relativity of simultaneity".

I get a different result. Using the Galilean transformation
equations and Einstein's idea for constant light speed we have

x'=x-vt
y'=y
z'=z
t'=t

Scientists say that the speed of light measures the same according
to a cesium clock in S' as measured by a cesium clock in S. Since t'
is already defined to be t in the Galilean transformation equations,
we cannot use t' to show time on a cesium clock in S'. We have to use
a different variable n'.

w=velocity of light
x=wt
x'=wn'

x'=x-vt
wn'=wt-vt
n'=t(1-v/c)

My result for this experiment is that a picture taken from
either frame of reference will show both clocks hitting the floor
simultaneously, and both pictures will show less time on the S' clock.
Robert B. Winn

You are free to reinvent 19th century theory. Just be aware that pictures
cannot provide the information that you claim they do, and that 19th century
theory has been disproved one century ago.

Regards,
Harald


.

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