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Re: What Do Dingleberries Actually Mean When They Claim Moving Clocks Run Slow?

From	Odd Bodkin <bodkinodd@gmail.com>
Newsgroups	sci.physics.relativity
Subject	Re: What Do Dingleberries Actually Mean When They Claim Moving Clocks Run Slow?
Date	2017-09-15 08:48 -0500
Organization	Aioe.org NNTP Server
Message-ID	<opglmk$1kng$1@gioia.aioe.org> (permalink)
References	(18 earlier) <b142c6ab-cb94-47e5-81c6-3328c099943d@googlegroups.com> <opbqc0$1ni1$3@gioia.aioe.org> <befcc5c2-0ff8-4fa3-81b2-49f20ae03e6c@googlegroups.com> <opdu6q$179n$3@gioia.aioe.org> <10926271-1a32-4de1-b14b-44080bbb4ae3@googlegroups.com>

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On 9/14/17 10:25 PM, gehan.ameresekere@gmail.com wrote:
> On Thursday, September 14, 2017 at 6:24:52 PM UTC+5:30, Odd Bodkin wrote:
>> <gehan.ameresekere@gmail.com> wrote:
>>> On Wednesday, September 13, 2017 at 11:07:10 PM UTC+5:30, Odd Bodkin wrote:
>>>>
>>>> As Einstein noted, if the signals are seen simultaneously by the track
>>>> observer, then they won't be seen simultaneously by the train observer.
>>>> And vice versa.
>>>>
>>>>>
>>>
>>> Why?
>>>
>>> Because the train observer is closer to one of the signals.
>>
>> In some kind of absolute reality? No. That's how the track observer would
>> account for it. But the train observer says, no, I'm still exactly midway
>> between the points of the lightning strikes.
> 
> Ah I get it. However this degree of clarity is not present in the explanation that Einstein himself gave in the book he wrote. Such clarity is appreciated.
> And the patience.

Yes, I understand the problem you're facing. The problem fundamentally 
lies in relying too heavily on one author to explain things completely 
fully and plainly. There IS NO SUCH TEXT anywhere.

The only way to understand relativity is to read MANY books on the 
subject, which will all have slightly different ways of presenting the 
same content, the same examples. That's not to say that one author's 
presentation is the correct one or the best one, but reading MULTIPLE 
treatments of the same thing give the reader better insight in his own mind.

In my experience, there is no other good way to do it. I know that 
meticulously picking through one presentation is not a good way to do it.

> 
>> Remember that the train
>> observer does NOT say that he is moving closer to the strikes.
> 
> OK he can say that.
> 
>> The earth's
>> surface is not a preferred frame for deciding who is moving and who is not.
>> The is nothing special about the earth's surface as a frame of reference.
>>
> 
> Indeed. The experiment should have taken place in outer space where you do not know if you are moving or not or relative to what and also if you see two flashes of light in the distance, you cannot tell, from the speed of the light measured by you, if you are moving or not. This also should have been explicitly stated by Einstein. But that was 100+ years ago, give him a break.
> 
>> The lesson here is that there is no "absolute truth" about one observer
>> being now closer to the signal. That is purely an arbitrary choice of
>> reference frame, which is the point Galileo himself made.
>>
> 
> As I mentioned the only information reaching each observer is a flash of light at either simultaneous times or different times. Not knowing if either one is moving relative to the sources, because the speed of light will not change for that observer even if he is moving towards the sources, neither one can tell which one happened earlier.

This isn't quite true.
Remember the source is an instantaneous strike. It has zero duration, 
and therefore even the idea of "motion" for this strike is meaningless. 
There are only two bits of information that are relevant here.
1. That the observer is midway between the lightning strikes, which he 
can verify at ANY TIME (even afterwards) by using a tape measure from 
where he was standing to the scorch mark on the train (for the train 
observer), or from where he was standing to the scorch mark on the track 
(for the embankment observer)>
2. That the speed of travel of the signal was the same for both sources. 
This again the observer can do with an INDEPENDENT light speed 
measurement, where all he is saying is that the speed of light doesn't 
change magically just because it came from lightning strikes. In this 
case, what Einstein didn't say explicitly but is definitely verified is 
that both the train observer and the track observer will have run those 
experiments and determined that the speed of light is c from either 
direction.

If you know the distances from the strikes are the same, and you know 
that the speed of the signal from the strikes are the same, then you 
definitely know that the time of propagation had to be the same. This is 
true for each observer: they both can fairly claim that the propagation 
time for the light to travel to themselves from both sources had to be 
equal. Therefore, if the observer sees the flashes simultaneously, then 
the original strikes MUST have happened simultaneously. If the observer 
sees the flashes nonsimultaneously, then the original strikes MUST have 
happened non-simultaneously.

Since the two observers come to different conclusions, there is no way 
to tell which of them is "really" right, and in fact that is the 
conclusion -- there is no "right" answer, there is only an 
observer-dependent conclusion.

> 
> But I think there is more to it 'than dreamt up in your philosophy Horatio'.
> 
>>>
>>> That is to say, if an observer is closer to one signal than the other, he
>>> will not see them flashes simultaneously.
>>>
>>> So what is new? That's old school stuff.
>>>
> 
> I will leave it to the reader to state what assumptions are rife in the above description of the train and tracks thought experiment. At least give me this: the above describes a real time scenario. No prior or after measurement of distances, times etc is permitted.
> 
> If you don't allow people to know where they are and what time it is, well then there is no simultaneity. But I am willing to bet our science can tell us what time it is, where we were and where we are.
> 

-- 
Odd Bodkin -- maker of fine toys, tools, tables

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