# Does Gravitational Time Dilation imply mass change?

1. Sep 24, 2010

### johne1618

According to Einstein's Gravitational Time Dilation, if an oscillating physical system is elevated to a height H above the Earth then in oscillates at a higher frequency than the same system at ground level.

According to Planck's relation between Energy and frequency this must mean that the oscillator at height H must have more energy, and thus by E=mc^2, must have more mass than the identical oscillator at ground level.

Is this true?

2. Sep 24, 2010

### ZapperZ

Staff Emeritus
That "m" is the rest mass.

I'm not sure why you need to invoke GR in this case. Why not also look at an atom in an excited state? Is the fact that an excited atom has more energy means that it has more "mass"?

Mass is not energy, and energy is not mass (there are already tons of threads on this issue on here). That Einstein equation is a conversion formula of going from one to the other. Why physicists are known to use mass-energy interchangeably, the general public has no such ability since they are often ignorant of what goes on under the covers.

Zz.