Let there be light: How to generate photons from nothing

From black holes we know the effect of Hawking radiation: If in vacuum a pair of photons is born in a random way and one of them falls into the black hole, the other one remains: light from nothing. The energy debt to the universe must be paid by the black hole, which is why it evaporates over many billions of years. But there is a second trick. With the black hole the gravity plays the role of the magician who makes the one photon disappear. But according to the equivalence principle of the gen...