Re: Re: C S Lewis

On 11 Jan 2006 15:58:01 -0800, "rja.carnegie@xxxxxxxxxx"
<rja.carnegie@xxxxxxxxxx> enriched this group when s/he wrote:

>
>Ye Old One wrote:
>> On Wed, 11 Jan 2006 12:33:38 -0000, "al"
>> <almond@xxxxxxxxxxxxxxxxxxxxxxxxx> enriched this group when s/he
>> wrote:
>>
>> >As I recall (and it's been a while) the thought experiment to prove time
>> >dilation was with a long rod with a light source and reflector at each end.
>> >The rod and attachments were travelling at relativistic speeds towards their
>> >destination end on. The light flashed at one end and was detected timed and
>> >returned by the other. In this way it was inferred that the shortening of
>> >the rod due to velocity would alter the time.
>> >If you agree with this I will continue.
>>
>> Then you may as well stop because the rod will never change length.
>
>It depends on the observer. Moving objects are foreshortened along the
>direction of movement. (However, from the point of view of the object,
>it's everything else that is moving and is foreshortened. Yes, this is
>a paradox, but it's still correct.)

And a cornerstone of relativity.
>
>The time dilation experiment is a train with a beam of light moving
>from ceiling to floor and back to the point of origin - there's a
>mirror on the floor. An observer in the train sees light moving in a
>straight line || An observer outside sees light travelling further \/
>because the target on the ceiling has moved. Since the speed of light
>is counted the same by each observer, they reach different naive
>conclusions about the time that has passed on the train. Special
>relativity means that each of their conclusions is correct.
>

Correct.

>But again, the observer on the train can watch the observer outside
>performing a similar experiment and draw the same conclusion - that the
>other guy is moving and /his/ clock is running slow. The paradox.
>
>Now if you shoot a beam of light along the axis of travel - from one
>end of the train carriage to the other - and then reflect it back
>again, the maths is different again. I suppose it's kind of like
>walking against the wind and then walking with the wind at your back -
>say you make 3 miles an hour in one direction and then 5 miles an hour
>the other direction, your average speed is not 4 mph, it's 3.75 mph.
>(60 miles is a good round number, but rather a long walk.)

Very true.

However, the point I made is 100% true - Al was wrong to claim the rod
would change length. One of our methods of testing the length - using
light as a range finder - would seem to say it has, but in fact it is
still the same length.

--
Bob.

.

Relevant Pages

  • Re: C S Lewis
    ... >>>dilation was with a long rod with a light source and reflector at each ... > It depends on the observer. ... > it's everything else that is moving and is foreshortened. ... > The time dilation experiment is a train with a beam of light moving ...
    (talk.origins)
  • Re: C S Lewis
    ... >>dilation was with a long rod with a light source and reflector at each end. ... It depends on the observer. ... it's everything else that is moving and is foreshortened. ... The time dilation experiment is a train with a beam of light moving ...
    (talk.origins)
  • Re: what is the relation between force and energy?
    ... then they are moving relative to each ... > while the other is standing outside watching the train pass by - take ... > accurate measurements with their own accurate clocks of the time it ... > comparison to the rate of the passage of time for the other observer ...
    (sci.physics)
  • Re: Can current theory explain the twin paradox?
    ... Electrodynamics of Moving Bodies", by Albert Einstein. ... | the other is positioned outside as the train goes by - take accurate ... | measurements with their own accurate clocks of the time it takes light ... | rate of the passage of time for the other observer standing alongside ...
    (sci.physics.relativity)
  • Re: Can current theory explain the twin paradox?
    ... Below is an excerpt from my essay, "The Time And Motion ... observers - one of whom is seated inside a moving passenger train while ... rate of the passage of time for the other observer standing alongside ... observers be that they are not moving at the same speed. ...
    (sci.physics.relativity)
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