# Why is measuring half life or oscillation in 2 different gravitational potential well a valid proof of time dilation?

It is often quoted that if one measure the rate of radioactive decay or oscillation in high gravitational field and low gravitational field the rate of radioactive decay or oscillation in high gravitational field will be slower than one of the low gravitational field.

This is use as a proof for gravitational time dilation. Since time is perceived to be running slower in high gravitation field as the current definition of time is bound to the oscillation of some atom.

However I cannot wrap my head around this, since it is possible that gravity merely effects the oscillation or radioactive decay process of an atom itself and not the concept of time.

How does scientist know that time is slowed and not the process itself?