# If a photon goes up, does it come down?

If light can be bent by gravity, does a mass as dense as a star pull any fraction of photons back towards itself?

• No. The photons just lose part of their energy. – CuriousOne Oct 10 '14 at 9:08

For visible stars, the answer is no. In Newtonian physics, a star that would pull something travelling at light speed back to itself, i.e. a star for which the escape velocity were $c$, was called a dark star and seems to have been first postulated by the Rev. John Mitchell in a paper to the Royal Society in London in 1783. The great Simon Pierre de Laplace postulated the same idea some years later. It is important to take heed that in theory there was nothing stopping something escaping a dark star by climbing a rope let down by a helpful spaceship, nor was there any known lightspeed limit in those days.