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Greetings,

This question concerns Einstein’s Equivalency Principle, of which I confess I am mostly ignorant.

Can you measure a gravity wave with a “point-sized” detector?

Einstein’s famous “thought experiment” involving his elevator leads us to the conclusion that acceleration and gravity are the same, yet the concept only works out if we shrink the elevator down to an infinitesimal. (Otherwise we can detect the gradient of the gravitational field of the planet and thus tell the difference between the effects of gravity and the effects of a moving elevator. )

But if I allow myself to shrink a measurement device down to an infinitesimal, could I still measure the passing of a gravity wave? It seems to me that all the methods for measuring gravity waves require extremely long paths that (I’m guessing) must span the “trough and valley” of a gravity wave. Would a “point-sized” measuring system (one that does not extend across a significant part of the gravity wave) simply ride “up and down” on the ripple of space-time and thus experience zero effects? Or would such an accelerometer (one that is not allowed to look outside of its localized area) be able to tell that it is being jiggled around?

My question stems from a concept in engineering.

a = “mechanical” acceleration

g = gravitational acceleration

a = g

da/dt = dg/dt

In engineering, da/dt is known as “jerk” which is one measure of mechanical shock.

But when trying to come up with an example of dg/dt, I can only think of gravity waves, and though jerk can be measured by a “point-like” accelerometer, I don’t know about gravity waves. And is there some limit to how small an ideal detector could be miniaturized before hitting some kind of quantum limit?

many thanks for your time,

Mark

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# Can a Gravity Wave be detected at a point ?

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