New Spin on Famous Physics Experiment Shows Light Interfering With Its Own Past

In 1801, British scientist Thomas Young carried out a 'double slit' experiment that has gone down in physics history: By shining light through two slits in a material, he showed that light behaved like a wave, taking different paths simultaneously only to interfere in predictable ways once they recombine.
Since that pioneering moment, the experiment has been repeated to demonstrate electromagnetic radiation displays both wave-like and particle-like behaviors. To put it another way, light can act like marbles rolling down a slope and like ripples in a pond, depending on how they're measured.
It's not just photons that act this way, either. Scientists have used similar setups to show electrons, neutrons, and whole atoms behaving in the same fashion, establishing a core tenet of quantum physics as a theory based on probability.
Now scientists have recreated Young's experiment with a modern twist. Instead of a pair of slits separated in space, they used 'time slits' created by rapid adjustments in the reflectivity of a material, testing the ability for a wave of light to interfere with its own past and future.
New Spin on Famous Physics Experiment Shows Light Interfering With Its Own Past