Re: Einstein's Train Gedanken Re-visited

"Bruce Richmond" <bsr3997@xxxxxxxxxxx> wrote in message news:dcf2a5b6-21b5-4d0f-bd5b-0ff69cf82776@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
On Jun 23, 10:54 pm, "Whoever" <no...@xxxxxxxxxxx> wrote:
"Bruce Richmond" <bsr3...@xxxxxxxxxxx> wrote in message
news:2939b7dd-20fb-43d8-9210-3f346f67e78f@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> For starters what you proposed and what you described were not the
> same thing.

Yes .. they are

> Your discription still had the clock(s) moving on the
> earth's surface.

No .. it clearly didn't. Only one of them.

Ok, I'll grant you that. I misinterperted what you were saying.

That's ok .. glad we cleared that up

==>> >> So .. what would happen if we moved the clocks apart at the same speed
>> >> according to the (almost) inertial frame of the center of the >> >> earth.
>> >> So
>> >> (for example) the one moving with the earth would stay 'still'
>> >> (relative
>> >> to
>> >> the earth) and the other one move away at twice the speed of >> >> earth's
>> >> rotation in the opposite direction.

==

See there "the one moving with the earth would stay 'still' (relative to the
earth) "

> So they are still moving along curved paths in the
> ECI system.

Yes they are

> Combine that with the fact that even the ECI system is
> not truly inertial and it becomes very unlikely that the effects will
> cancel out.

>http://en.wikipedia.org/wiki/Earth_Centered_Inertial

> "It should be noted that ECI frames are not truly inertial since the
> Earth itself is accelerating as it travels in its orbit about the
> Sun."

Grr ... Picky .. so the only affect is due to the movement of the earth
around the sun and the sun around galactic core, and whatever non-inertial
movement the galaxy may have.

So .. ignoring those effects .. treating the ECI as inertial for the sake of
this thought experiment .. (which seemed to be obvious from context, but I
see we need to make it explicit) what do you claim about the clocks as
described?- Hide quoted text -

- Show quoted text -

I thought the whole purpose of this exercise was to get clocks in sync
without using light signals so that a real world experiment could be
done to measure one way light speed isotropy.

Yeup .. this would be one way to do it .. moving one way westward with the appropriate speed would keep it in sync.

Or ... put both clocks on a train heading west at the appropriate speed , and do mutual clock transport there and they'd be in sync and the train frame would then be (close to) inertial. Again, we're ignoring here the orbit of the earth, perturbations from other bodies, movement of sun around galaxy etc. its pretty much impossible to get a perfectly inertial frame .. and that a suitable train and track (or plane) would be very impractical :)

So besides the slight non-inertial effects you mentioned above you
will also have the problem that the clock will get out of sync due to
the acceleration to get it up to speed and deceleration stop it.

You could avoid that by transferring time setting to another 'stationary' clock at the appropriate point when the moving clock goes past. A bit like the twins paradox version that uses three clocks to avoid acceleration issues.

You also have the problem that after stopping the transported clock,
even if it is in sync, the clocks are not at rest in the ECI system.

But they are accelerating (rotating) the same, so would stay in sync with each other.

If you manage to throw a ball to someone on the other side of a merry-
go-round while it is spinning its time of flight will be different
than if it weren't spinning.

Yeup .. and if you throw it "at" then, it will miss :):) Always a fun game to try when you're on a merry-go-round

Yes, it's my turn to be picky ;)~

:):)


.

Relevant Pages

  • Re: Einsteins Train Gedanken Re-visited
    ... the one moving with the earth would stay 'still' ... see we need to make it explicit) what do you claim about the clocks ... appropriate speed would keep it in sync. ... frame would then be inertial. ...
    (sci.physics.relativity)
  • Re: Einsteins Train Gedanken Re-visited
    ... the one moving with the earth would stay 'still' ... I thought the whole purpose of this exercise was to get clocks in sync ... frame would then be inertial. ...
    (sci.physics.relativity)
  • Re: Einsteins Train Gedanken Re-visited
    ... the one moving with the earth would stay 'still' ... see we need to make it explicit) what do you claim about the clocks as ... appropriate speed would keep it in sync. ...
    (sci.physics.relativity)
  • Re: Einsteins Train Gedanken Re-visited
    ... the one moving with the earth would stay 'still' ... I thought the whole purpose of this exercise was to get clocks in sync ... frame would then be inertial. ...
    (sci.physics.relativity)
  • Re: Einsteins Train Gedanken Re-visited
    ... the one moving with the earth would stay 'still' ... see we need to make it explicit) what do you claim about the clocks ... appropriate speed would keep it in sync. ... frame would then be inertial. ...
    (sci.physics.relativity)
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