Re: Length definition in SR - can anyone explain


"David" <dseppala@xxxxxxxxxxxxx> wrote in message news:v8lc42dpp731snaggm8eg2me89b5ne4q77@xxxxxxxxxx
I'm trying to understand fundamental concepts of SR like time and
length. In my posting about clocks I got a varied opinions of what
constitutes a clock. This posting is a question about lengths. Can
anyone explain why this is or isn't allowed in SR?

I'm in an inertial frame. Since the speed of light is constant I
decide to make my standard unit of length equal to one light-second
(the distance light travels in one second as measured by synchronized
clocks in my inertial frame).

Now let there be an inertial frame moving along the x axis with
velocity V = 0.866c relative to my frame.
At time t0 I fire two lasers for a one second burst. The length of
each pulse is one light-second. The lasers are aligned along the
x-axis. One points in the positive direction, the other points in the
negative direction.

The moving observer measures the length of one pulse to be much less
than the length of the other pulse even though in my frame they are
identical.

What makes you decide that?
Try to explain your reasoning by defining some relevant
events and calculating the lenghts of the pulses in the
moving frame. Start by drawing a little spacetime diagram.
Hint: in your equations, use the variable v in stead of the
numeric value 0.866c.

Dirk Vdm


.

Relevant Pages

  • Re: Length definition in SR - can anyone explain
    ... This posting is a question about lengths. ... I'm in an inertial frame. ... The moving observer measures the length of one pulse to be much less ... about the range of speeds my photon emitting device can have and the ...
    (sci.physics.relativity)
  • Re: Length definition in SR - can anyone explain
    ... In my posting about clocks I got a varied opinions of what ... I'm in an inertial frame. ... The moving observer measures the length of one pulse to be much less ...
    (sci.physics.relativity)
  • Re: Einsteinian Poor Logic.
    ... Two identical clocks are connected by a rod of length L and are moving past ... both each other and the stationary ones, in the stationary frame. ... L. A RH moving pulse takes L/seconds to do the same. ...
    (sci.physics.relativity)
  • Re: Length definition in SR - can anyone explain
    ... In my posting about clocks I got a varied opinions of what ... I'm in an inertial frame. ... The moving observer measures the length of one pulse to be much less ... moving frame. ...
    (sci.physics.relativity)
  • Re: Ive proved Einstein Wring. What Happens Now?
    ... O2 can synch his clocks at any time using Einstein's defined method since they ... are at rest in his frame. ... In the experiment, a light pulse is emitted by S towards O2's mirror, M. ... Therefore, in O1's frame, the pulse's travel time between C1 and C2 on forward ...
    (sci.physics.relativity)