Can you cut a single photon, a particle of light, in half? Physicists at the University of Oslo worked through the math of an imagined version of that experiment. A photon heads toward a mirror, and its front half bounces back. Then the mirror is suddenly removed, so the back half keeps going.
The result is not two half-sized photons. Instead, the math predicts a quantum superposition: a mix of possible outcomes with anywhere from zero to a very large number of new photons. Removing the mirror more slowly makes small numbers of photons more likely than big swarms. The paper, by I.C.O. Rukan, J. Gulla and Johannes Skaar, has been accepted by Physical Review Letters. It is a theoretical result, not an experiment, and the team plans to check whether cutting other particles, like electrons, gives similar results.
Why it matters: It’s a reminder of how strange quantum physics is. To see what superposition means, check out our quantum superposition lesson.