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Subject: 
Re: Relativity Question
Newsgroups: 
lugnet.off-topic.geek
Date: 
Wed, 8 Nov 2000 21:32:13 GMT
Viewed: 
2404 times
  
In lugnet.off-topic.geek, Dave Schuler writes:
> In lugnet.off-topic.geek, Jay Jacinto writes:
> 
> > For example:  an observer accelerating away from a stationary observer would
> > experience the sensation of acceleration.  Conversely, the stationary • observer
> > would experience a gravitational field generated by the Universe accelerating
> > from the other observer.  So neither could determine which is in the
> > accelerated inertia frame.  Thus, all motion including acceleration is
> > relative.
> 
>  Well, thanks for throwing a monkey wrench into it for me.  How do the
> famous de-synchronized clocks fit into this?  Obviously one of them slowed
> down relative to the other.  Do we infer that the ground-based clock
> decelerated sufficiently to speed up time's local passage?  I thought I had
> a handle on this, but now I see I'm missing something.

Acceleration is bad ju-ju, since it isn't accounted for in special relativity.
It's only in General Relativity that we get gravity thrown into the mix, and
that's taught in grad school.  However, from a strictly special relativistic
POV the observer that is actually moving measures time slower than a stationary
observer as determined by the Lorentz transform.  In this example there are
only two inertia frames, the rest of the universe is ignored.

> > Also the doppler shift measured by each observer will be the same, all
> > acceleration does is add an additional term as determined by the Lorentz
> > transformation.

I think I goofed here concerning the additional term from acceleration.  The
frequency of light emitted is determined only by *instantaneously* velocity and
the wavelength of light.

>  Hmm.  This is the part that always messes me up.  So if there is a distant
> star whose light we see as red-shifted, and X is standing on Earth, while Y
> takes off at .9c toward the distant star, will both X and Y perceive the
> same red-shift?
> 
>     Dave!

Yep, if we consider at least one of the objects to be at "rest." The actual
factor that determines the doppler shift is the following:

sqrt((1 + ß)/(1 - ß))

which is the classical doppler shift with some simplication.

ß = v/c
v = velocity

I feel like I'm digging a very deep hole for myself with all this.

Thanks
Jay Jacinto



Message is in Reply To:
  Re: Relativity Question
 
(...) Well, thanks for throwing a monkey wrench into it for me. How do the famous de-synchronized clocks fit into this? Obviously one of them slowed down relative to the other. Do we infer that the ground-based clock decelerated sufficiently to (...) (26 years ago, 8-Nov-00, to lugnet.off-topic.geek)

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