Re: Are *observed* SR effects real?

On Jul 17, 8:06 am, mluttg...@xxxxxxxxxx wrote:
On Jul 17, 12:21 am, PD <TheDraperFam...@xxxxxxxxx> wrote:



On Jul 16, 2:48 pm, mluttg...@xxxxxxxxxx wrote:

On Jul 16, 4:16 pm, PD <TheDraperFam...@xxxxxxxxx> wrote:

Yes, you wrote that, but I added to the scenario that
Stan asked Tom to also measure the length of the train by
using the ruler on the train itself. Then, Tom found
600 m.

The ruler that Tom used was a ruler on the train itself. It yielded
400 m from where he was standing to the brush on the train, and 400 m
from where he was standing to the other brush on the train. I am
reporting to you what he *observed*.

This is not possible in Tom's rest frame.

Yes it is. As I told you, and according to the plan of attack agreed
upon, I am telling you what the *observations* ARE. These observations
turn out to be completely consistent with the actual documented
observations in real, equivalent experiments done by real people and
recorded in real articles in real journals in real libraries.

What I am going to do NEXT is show you that this *observation*, as
surprising as it is to you, is completely consistent with the laws of
physics.

Moreover, it appears that you've already lost a grip on the train of
thought. Let me see if I can recap for you:
1. Stan knows that the yellow flash marks the back of the train, and
the green and red flashes both mark the front of the train. But he
chooses the green flash because *he* says the yellow and green flashes
are simultaneous, and using *simultaneous* marks is essential to the
definition of physical length. He could use the location of the red
flash, but that wouldn't satisfy the definition of length because the
red and yellow flashes are not simultaneous. So for him, the green and
yellow flashes are the simultaneous marks that mark the length of the
train.
2. Tom agrees that the yellow flash marks the back of the train, and
that the green and red flashes both mark the front of the train. But
he uses the red flash, because *he* says the yellow and red flashes
are simultaneous, and using simultaneous marks is essential to the
definition of physical length. He could use the location of the green
flash, but that wouldn't satisfy the definition of length because the
green and yellow flashes are not simultaneous. So for him, the red and
yellow flashes are the simultaneous marks that mark the length of the
train.

So you see, what you say is "impossible" is quite possible, given what
they actually *observe*, given the *definition* of simultaneity, and
given the *definition* of physical length. Start with what they
*observe* as given FACTS, and then think through the conclusions of
that, rather than starting off by insisting what is possible or
impossible in your head.

The FACTS (the observations) as I stated them are FACTS. They echo
what is actually seen in equivalent experiments. Start with those as
GIVENS, and find out what consequences follow from that. GIVEN those
observations, and using the *definitions* of simultaneity, then one
cannot escape the fact that different sets of flashes are simultaneous
for Stan and Tom. And then given that fact, and the *definition* of
length, then it is immediately obvious that the length of the train
will be different for Stan and Tom, because they're using different
flashes to mark the ends of the train simultaneously.

Let's see if you have any questions about this again, before we go on
to show that the FACTS (observations) are consistent with the laws of
physics.

Nevertheless, according to SR, in his rest frame,
Tom would find *with his ruler*  that the length of the
train is 600 m, not 800 m.

No, SR does not say this at all. I don't know where you got the
impression this is the case.
(If it helps, let's leap ahead a little bit and note that the 600 m
that Stan measures for the length of the train is the Lorentz-
contracted length. What Tom measures is the rest length, because of
course in Tom's frame, the train is at rest, and that is of course
longer than what Stan measures.)

Let me know if this helps and we're ready to go on.

If, on the train, he measured the distance between
the yellow and red flashes that he observed, I agree
that he found 800 m.

Marcel Luttgens

You are not *adding* to the scenario. You are *changing* the scenario.
The observations that are in my scenario are consistent with setups
and results in equivalent experiments recorded in the literature. The
*altered* scenario you just proposed is inconsistent with experimental
results in the literature.

It is nevertheless interesting, because it gives you the
opportunity to show that the addition c + v (v being the
the velocity of the train) must be rejected.

But just to bring us back on track, the key thing is that, according
to the observations made, the yellow and green flashes are
simultaneous for Stan but not for Tom, and the yellow and red flashes
are simultaneous for Tom but not for Stan.

Yes, that's the main point. I am looking forward to reading
the following episode.

Marcel Luttgens- Hide quoted text -

- Show quoted text -

.

Relevant Pages

  • Re: Are *observed* SR effects real?
    ... Stan asked Tom to also measure the length of the train by ... the green and red flashes both mark the front of the train. ...
    (sci.physics.relativity)
  • Re: Are *observed* SR effects real?
    ... Stan asked Tom to also measure the length of the train by ... the green and red flashes both mark the front of the train. ...
    (sci.physics.relativity)
  • Re: Are *observed* SR effects real?
    ... Stan asked Tom to also measure the length of the train by ... the green and red flashes both mark the front of the train. ...
    (sci.physics.relativity)
  • Re: Are *observed* SR effects real?
    ... Stan asked Tom to also measure the length of the train by ... the green and red flashes both mark the front of the train. ...
    (sci.physics.relativity)
  • Re: Are *observed* SR effects real?
    ... Stan asked Tom to also measure the length of the train by ... the green and red flashes both mark the front of the train. ...
    (sci.physics.relativity)
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