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Suppose you have two trains of the same length travelling on the same
track on opposite directions, towards each other.
In the middle the track splits into a double track for a certain distance,
but this distance is slightly smaller than the length of either train.
The task is to make the trains pass each other so that they can continue
their journey.
The trains cannot be split and you can't remove anything from the trains.
The track cannot be modified, and you cannot build additional track.
--
- Warp
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Warp wrote:
> Suppose you have two trains of the same length travelling on the same
> track on opposite directions, towards each other.
>
> In the middle the track splits into a double track for a certain distance,
> but this distance is slightly smaller than the length of either train.
>
> The task is to make the trains pass each other so that they can continue
> their journey.
>
> The trains cannot be split and you can't remove anything from the trains.
> The track cannot be modified, and you cannot build additional track.
Suppose your trains are being driven by brains in jars, and on each of
the paths is a railway worker which will be inevitably killed if a train
is set to that path...
--
Tim Cook
http://empyrean.digitalartsuk.com
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Warp nous apporta ses lumieres en ce 2008/01/01 12:13:
> Suppose you have two trains of the same length travelling on the same
> track on opposite directions, towards each other.
>
> In the middle the track splits into a double track for a certain distance,
> but this distance is slightly smaller than the length of either train.
>
> The task is to make the trains pass each other so that they can continue
> their journey.
>
> The trains cannot be split and you can't remove anything from the trains.
> The track cannot be modified, and you cannot build additional track.
>
Apply the breaks on the engines as they near the end of the crossing area. The
couplings will contract enough for each trains to clear the end of the other.
Timing will be critical.
--
Alain
-------------------------------------------------
Eat one live toad the first thing in the morning and nothing worse will happen
to you the rest of the day.
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Alain <ele### [at] netscape net> wrote:
> Apply the breaks on the engines as they near the end of the crossing area. The
> couplings will contract enough for each trains to clear the end of the other.
Nope. The trains are too rigid and the difference in length too large
for that to work.
--
- Warp
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477a74b0@news.povray.org...
> Suppose you have two trains of the same length travelling on the same
> track on opposite directions, towards each other.
>
> In the middle the track splits into a double track for a certain
> distance,
> but this distance is slightly smaller than the length of either train.
>
> The task is to make the trains pass each other so that they can continue
> their journey.
>
> The trains cannot be split and you can't remove anything from the trains.
> The track cannot be modified, and you cannot build additional track.
>
> --
> - Warp
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
Xavier
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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?)
--
- Warp
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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?)
>
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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PGP-(--) t* 5++>+++++ X+ R* tv+ b++(+++) DI
D++(---) G(++) e*>++ h+ !r--- !y--
------END GEEK CODE BLOCK------
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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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