One recent experiment backs up Minkowski's answer — but still may not prove Abraham wrong. One might expect that the momentum of a photon, under almost any conditions, would no longer be a ...

Traditionally, textbooks teach us about vertical optical transitions, where a material absorbs light with the photon changing only the electron's energy state. "However, momentum-enhanced photons ...

It can also exist for properties that are harder to imagine, such as angular momentum. This property is divided into spin, which is related to the photon's rotation of the electric field ...

Two-photon emission is a relatively weak emission process, about five orders of magnitude weaker than the usual single-photon emission that occurs in semiconductor lasers or LEDs. So we had to use ...