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Re: [Phys-L] another DIY relativity experiment

David,
Thanks for the helpful details.

Bob Sciamanda
Physics, Edinboro Univ of PA (Em)
treborsci@verizon.net
www.sciamanda.com

-----Original Message----- From: David Bowman
Sent: Saturday, May 21, 2016 12:33 AM
To: Phys-L@Phys-L.org
Subject: Re: [Phys-L] another DIY relativity experiment

Regarding Bob S's question/confusion:

I wrote:

"2) If you compare ALL the changes occurring on a ship in a
strong gravitational field to the "same" type changes on a ship
in gravity free space, you will measure a relative slow down
(GR)."
*************************************************************
I do have a serious problem with this statement. It is that the
rate of some changes are, by their physics, already dependent on
the strength of local gravity. For instance, a clock whose
period is determined by a pendulum would not even work on the
ship which is in gravity free space!

A pendulum clock would work just fine and keep the correct proper on board time in any intergalactic spaceship accelerating at one g w.r.t. any locally inertial frame. This just means the spaceship needs to have its engine thrust running so the ship accelerates at 1 g in order for for the pendulum to work correctly. In fact, on such a deep space accelerating spaceship fixed locations toward the bottom (w.r.t. the artificial gravitational acceleration field) on the ship will have their clocks tick slower than fixed locations on the ship toward the to top of it by a factor of (1 + g*dz/c^2) where dz is the spatial height separation of the two locations on different parts of the ship. Likewise, on Earth, a pendulum clock will not work correctly in a freely falling elevator, either. In both situations the conditions for the operation of the clock need to be met.

So the above statement
opens the question of how it applies to phenomena whose physics
of time evolution includes a dependence on gravity apart from
any relativistic effects? I am not at all a GR expert - I am
confused!

Recall the Equivalence Principle and apply it in properly corresponding situations.

David Bowman
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