[time-nuts] NPR Story I heard this morning

Henry Hallam henry at pericynthion.org
Mon Nov 3 16:28:47 EST 2014

On Mon, Nov 3, 2014 at 1:18 PM, Mike Feher <mfeher at eozinc.com> wrote:
> Anyway, regarding time and gravity, I certainly believe the mathematics of Einstein and others, however, I have a hard time believing that man-made instruments to measure the effects of gravity on time is valid. For example in a Cesium clock, time is a function of the transition time between two hyperfine lines of Cesium atoms. So, does gravity affect this transition time within the Cesium atoms? It may very well, but, I am not smart enough to know that. Maybe someone can help.

This may not be a very satisfactory explanation, but in a nutshell
it's not the atomic transition time that changes with gravitational
potential, but *time itself*.  And remember, it's a *relative* effect
- you can only measure it when you compare two clocks at different
heights, never just by looking at one by itself, no matter how good it

> Also, when someone mentioned moving a very sensitive scale up in elevation and noting the difference due to gravitational effects, also seems odd to me. Seems like even in the most sensitive scales, weight is measured as the difference between the weighing platform and the body of the instrument. Here again, moving the whole assembly up in elevation it would seem to me that gravity would affect both the platform and the body, and the relative weight indicated should remain the same. What am I missing besides gray matter? Thanks - Mike

Weighing scales do not work by measuring the gravitational attraction
between the scale and the object to be measured.  They measure the
attraction between the earth and the object to be measured. When you
go up a hill, you move the apparatus and the object, but not the


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