Time dilation of your local clock is what an observer moving relative to you
measures. Your local time is the same as always according to your clocks
particularly when you are moving at a constant velocity and not subject to
acceleration. SR reveals that any beam of light that you generate under these
conditions within your local time frame travels at a measured velocity of c,
according to your instruments, regardless of the direction it travels. It does
not matter that you might be traveling at a velocity that approaches c relative
to any other observer. The external observer will see Doppler shifts, etc.
depending upon their motion relative to you. All observers must see a world
that is consistent with the laws of physics.
Dave
-----Original Message-----
From: leaking pen <itsat...@gmail.com>
To: vortex-l <vortex-l@eskimo.com>
Sent: Sat, Nov 16, 2013 7:30 pm
Subject: Re: [Vo]:Local Calculated Velocity of Space Ship
I'm lost. Time dilation would continue to effect the synchonized clock, right?
On Fri, Nov 15, 2013 at 10:17 PM, <jwin...@cyllene.uwa.edu.au> wrote:
On 16/11/2013 12:25 PM, leaking pen wrote:
However if we consider ourselves using our initial clock
synchronisation, then we know our true accumulated speed
because we can see that the light pulse is only just
travelling a bit faster than us (it takes the pulse a very
long time to travel from the back of the ship to the front)
and so we are travelling just a shade slower than c. Also
since any clock tick rate is given by an oscillation
time, if we use the round trip time of a light pulse
travelling from the back of the ship, to the front and back
again, as our oscillation tick time, then we know that our
time is ticking a lot slower than it was before we
accelerated. If we divide the known distance (10 light years)
by our speed measured this way (~0.99c or thereabouts) then we
know how many ticks of our (slowed down) clock will happen in
that distance - and it will be 1 years worth. Since our
clock seems to us to be ticking at its normal rate, we
will get there in what feels to us like a year."
Wouldnt the light take the same amount of time per our observation
to travel the ship? Isn't that fact basically defined by
relativity?
The question is how do you measure the time? If you measure the round
trip time, then Yes it never changes - because that is our definition of
time. But if we want to measure the *one-way* velocity so that we can
compare it with the other *one-way* velocity, then we need two clocks - one
at each end. If we synchronise these clocks by any means just before we
make the measurement, then Yes - again it takes exactly the same amount of
time to travel in each direction along the length of the ship. That is
guaranteed by our synchronisation technique.
But .... if we keep the initial synchronisation that was established
before we started accelerating, then using this time at each end of the ship
and pulses of light traversing this distance, we can discover our speed
relative to when the clocks were initially synchronised - and this can
indicate a speed in excess of c!
Consider the Eiffel tower experiment. The clock at the top runs faster
and the time difference accumulates until a light pulse sent from the top
when the clock reads say 10am, could arrive at the bottom clock when it
reads 9:59:59 - which is before it left! This same effect occurs without
any gravitational field to mess with time, and only with the help of
acceleration. If you got a reading like this from your space ship
measurement, you would know that you had accelerated such that your
accumulated speed relative to when you synchronised your clocks was greater
than c.
