Question

Suppose you were far from a planet that had a very strong gravitational field, and an emission line spectrum source on the surface of the planet. when you observe a similar source in your own spaceship, the wavelength of the light is 656.3 nm. what wavelength do you see when you look at the light source on the planet?

Answer 1

The answer would be it will be longer than the 656.3 nm. The reduced mass of positronium is less than hydrogen so the photon energy will be a reduced amount of for positronium than for hydrogen. So this will mean that the wavelength will be lengthier.