Warp wrote:
> Xavier Manget <NOS### [at] freefr> wrote:
>> If the trains' speeds are close enough to the speed of light, because of 
>> relativistic length contraction  (and with correct timing) the trains will 
>> have enough length to pass each other on the double track?...
> 
>> Did I get it? :-p
> 
>   Yes.
> 
>   (Had you heard of the thought experiment, or did you figure it out on
> your own?)
> 
Did you, or the person that came up with this idea, actually do the math 
for these three reference systems? just curious.

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Warp wrote:
> Xavier Manget <NOS### [at] freefr> wrote:
>> If the trains' speeds are close enough to the speed of light, because of 
>> relativistic length contraction  (and with correct timing) the trains will 
>> have enough length to pass each other on the double track?...
> 
>> Did I get it? :-p
> 
>   Yes.
> 
>   (Had you heard of the thought experiment, or did you figure it out on
> your own?)

I'm skeptical.  The version that I read involved a king and a large 
piece of lumber that was longer than the Great Hall and a wager about it 
fitting between the two doors, using relativity to boil down to 
*appearing* to fit in the hall, saying nothing about actually changing 
dimensions.

-- 
Tim Cook
http://empyrean.digitalartsuk.com

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D++(---) G(++) e*>++ h+ !r--- !y--
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andrel <a_l### [at] hotmailcom> wrote:
> Did you, or the person that came up with this idea, actually do the math 
> for these three reference systems? just curious.

  Not me, but the math has been done, of course.

  From the reference point of the track, both trains contract by a
certain amount and can pass each other on the double track.

  From the reference point of one of the trains the double track is
contracted, but the other train is contracted even more. From this
reference point the other train is so short that it travels the double
track in the same time as this train.

-- 
                                                          - Warp

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Tim Cook <z99### [at] bellsouthnet> wrote:
> I'm skeptical.  The version that I read involved a king and a large 
> piece of lumber that was longer than the Great Hall and a wager about it 
> fitting between the two doors, using relativity to boil down to 
> *appearing* to fit in the hall, saying nothing about actually changing 
> dimensions.

  Relativistic contraction is not a simple optical illusion. It is a
true physical contraction.
  If you think that it's only an optical illusion then the train track
thought experiment will seem counterintuitive and impossible. However,
AFAIK if relativity is right, the trains do indeed pass each other
without colliding. It's not only an optical illusion, but a true
contraction.

  The thought experiment is mentioned here:
http://en.wikipedia.org/wiki/Ladder_paradox#Relativistic_trains_passing

-- 
                                                          - Warp

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477abc37@news.povray.org...
> Xavier Manget <NOS### [at] freefr> wrote:
>> If the trains' speeds are close enough to the speed of light, because of
>> relativistic length contraction  (and with correct timing) the trains 
>> will
>> have enough length to pass each other on the double track?...
>
>> Did I get it? :-p
>
>  Yes.
>
>  (Had you heard of the thought experiment, or did you figure it out on
> your own?)

I figured it out on my own :-) ... I've learned a little about special 
relativity at school (20 years ago) but I really don't feel comfortable with 
it, I find it so counter-intuitive...

Xavier

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Xavier Manget <NOS### [at] freefr> wrote:
> I figured it out on my own :-) ... I've learned a little about special 
> relativity at school (20 years ago) but I really don't feel comfortable with 
> it, I find it so counter-intuitive...

  There's too much physical evidence to support relativity that it's just
impossible to deny that it gets at least pretty damn close to how the
universe really works.

  Given the right circumstances I'm convinced that this thought experiment
could indeed work in reality. (Of course it couldn't be done with actual
trains, but something similar could work.)

-- 
                                                          - Warp

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Warp wrote:
>   Not me, but the math has been done, of course.

I was wondering about that.

>   From the reference point of one of the trains the double track is
> contracted, but the other train is contracted even more. From this
> reference point the other train is so short that it travels the double
> track in the same time as this train.

But the conductor of the eastbound train will see the westbound train 
get onto the tracks later than he does, and vice versa. I'll believe the 
math was done, but I wouldn't necessarily believe this is a solution 
without anyone competent having done the math. :-)

-- 
   Darren New / San Diego, CA, USA (PST)
     It's not feature creep if you put it
     at the end and adjust the release date.

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Warp wrote:
>   There's too much physical evidence to support relativity that it's just
> impossible to deny that it gets at least pretty damn close to how the
> universe really works.

It's funny how many people won't deny something unintuitive like quantum 
mechanics or relativity, stuff that's really hard to understand properly 
even *with* math, but they're happy to deny the possibility of 
evolution, which is easy to explain without any mathematics.

As one poster recently repeated here, "f'ed up world!"

-- 
   Darren New / San Diego, CA, USA (PST)
     It's not feature creep if you put it
     at the end and adjust the release date.

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Darren New wrote:
> But the conductor of the eastbound train will see the westbound train 
> get onto the tracks later than he does, and vice versa. 

Actually, I meant to say "may see" there. And it looks like based on 
that wikipedia article that the conductor will actually see the other 
train get to its junction *before* he gets to his own. Very strange.

-- 
   Darren New / San Diego, CA, USA (PST)
     It's not feature creep if you put it
     at the end and adjust the release date.

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Darren New <dne### [at] sanrrcom> wrote:
> It's funny how many people won't deny something unintuitive like quantum 
> mechanics or relativity, stuff that's really hard to understand properly 
> even *with* math, but they're happy to deny the possibility of 
> evolution, which is easy to explain without any mathematics.

  That may be because we can check the theory of relativity here and
now, but we can't go back in time a few million years to check evolution
nor we can perform evolutionary experiments which require a few millions
of years.

-- 
                                                          - Warp

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