Re: Time Flow in Different Gravity Potentials.


"Henri Wilson" <HW@..> wrote in message news:jmi9r11971oked195nq1dsn4dn33mhlbc1@xxxxxxxxxx
> When reading about Einstein's 'theory', I persistently come across the claim
> that "time moves at different rates in different gravity potentials".

In case you don't understand what this means in standard
classical physics lingo...
It means that when two observers each measure the time
difference (dt and dt') between any pair of events, they
find that the rate dt/dt' is not 1, but that it depends on
quantities that can be interpreted as the observer's
gravitational potentials, dependent on their location only.

The usage of the verb "move" comes from the fact that
time can be naively imagined as the movement of a finger
of a clock. When you compare that movement to your
time, you actually calculate the rate dt/dt which gives the
velocity of that movement. This trivially gives of course
dt/dt = 1
which means that your clock finger moves at a constant
unit velocity, aka time rate.
That is expressed as: "your time moves at a constant rate".

When you compare the "movement of your clock finger"
to another observers' time (t'), then in general you find that
dt/dt' <> 1
which is expressed as "your time and the other observer's
move at different rates"

In cases where the above rate dt/dt' can be expressed
as functions of two locations only where in Newtonian
physics there would be "different gravity potentials", it
is said that "your time and the other observer's time
move at different rates in different gravity potentials".

Dirk Vdm


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