Scientists from the University of Queensland, Australia, have used single particles of light (photons) to simulate quantum particles travelling through time. They showed that one photon can pass through a wormhole and then interact with its older self. Their findings were published in Nature Communications.
The source of this time travel conundrum comes from what are called “closed timelike curves” (CTC). CTCs are used to simulate extremely powerful gravitational fields, like the ones produced by a spinning black hole, and could, theoretically (based on Einstein’s theory of general relativity), warp the fabric of existence so that spacetime bends back on itself – thus creating a CTC, almost like a path that could be used to travel back in time.