Re: = c + v (train)
From: The Ghost In The Machine (ewill_at_aurigae.athghost7038suus.net)
Date: 06/07/04
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Date: Mon, 07 Jun 2004 06:03:48 GMT
In sci.physics, Jim Greenfield
<greenfield_7@hotmail.com>
wrote
on 6 Jun 2004 17:34:38 -0700
<3c4afb26.0406061634.16d8db43@posting.google.com>:
> The Ghost In The Machine <ewill@aurigae.athghost7038suus.net> wrote in message news:<iibbp1-7r7.ln1@lexi2.athghost7038suus.net>...
>> In sci.physics, Jim Greenfield
>> <greenfield_7@hotmail.com>
>> wrote
>> on 6 Jun 2004 00:28:03 -0700
>> <3c4afb26.0406052328.69b02ba0@posting.google.com>:
>> > Sam Wormley <swormley1@mchsi.com> wrote in message news:<40BFAEFF.4C121AA3@mchsi.com>...
>> >> kenseto wrote:
>> >
>> > Answer this (I wish!!!!!):
>> > A train is speeding through a tunnel at high speed. There is NO light,
>> > either within the train, or to observe it by. What is the amount of
>> > its shrinkage?
>>
>> None relating to the train itself, as there are no
>> observers in the tunnel, just the train. The tunnel,
>> of course, has shrunk relative to the train, but that's
>> not directly observable because there's no light -- I'm
>> assuming you're postulating a cloudy, moonless night, with
>> no streetlights or other such nearby.
>
> You are getting there!!!! Key words "None,,,,,,as there are no
> observers" How can a physical event (shrinking) POSSIBLY be influenced
> by whether it is being "observed" or not??????? If you follow this
> logic (which I now hold you to), SR contraction has only occurred
> since life began (and there were observers).
The SR/GR phenomena depend entirely on where the observer
is. From the train's standpoint, the tunnel has shrunk
but the train has not. From the tunnel's standpoint,
the train has shrunk but the tunnel has not. From a train
approaching from another direction, both would shrink
(by differing amounts).
Sam Wormley is incorrect in that Newtonian mechanics are correct
here. However, the difference is so slight it's safely ignorable
in this case -- and in any event setting c = +oo (or v/c = 0)
will result in Newtonian mechanics anyway. The error introduced
here is approximately 1 part in 10^13, and an atom is about
10^-10 m in diameter.
>>
>> (It would be a small effect anyway as bullet trains traveling 120
>> m/s are only traveling 4 * 10^-7 c, which translates into
>> a gamma of approximately 1 - 8*10^-14 c. If the train is
>> 120 m long, the width adjustment is a fraction of an atom.)
>
> Stop wriggling. I gave you credit fot having more imagination than
> this.
> Jim G
You stop wriggling. Fast-moving muons do not decay at the same
rate stationary ones do (as indirectly observed by scientists
looking at their tracks in a cloud chamber-type experiment). Why is that?
There's also the engineering of a *deliberate* slowdown in the
frequency broadcast by the GPS satellites.
-- #191, ewill3@earthlink.net It's still legal to go .sigless.
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