Physicists at MIT have developed a theoretical technique inspired by the film Interstellar to send messages backwards in time using quantum entanglement. The approach mimics closed time-like curves and surprisingly improves communication through noisy channels. While actual time travel remains impossible, the idea could enhance conventional systems.
Physicists explore backwards time communication. A team led by Seth Lloyd at the Massachusetts Institute of Technology has proposed a new way to send messages into the past, drawing from general relativity's closed time-like curves (CTCs). These paths allow objects to loop back through time, though creating them requires immense energy at cosmic scales. Quantum entanglement offers a workaround, where particles link states across distances, potentially signaling backwards in time, Lloyd explained. In 2010, his group mimicked a CTC with entangled photons, simulating a photon traveling nanoseconds into the past to interact with itself. The new model imagines a noisy, faulty CTC channel. Surprisingly, communication works better backwards than forward in equivalent noisy setups, as analyzed using information theory. Team member Kaiyuan Ji noted inspiration from Interstellar, where Matthew McConaughey's astronaut manipulates a watch to message his daughter. “The father remembers how the daughter decodes his future message, so he can instruct himself on what is the best way to encode the message,” Ji said. Lloyd emphasized practical benefits: “Nobody’s built an actual physical, closed time-like curve... But all channels are noisy.” He suggested turning the result into an experiment like the 2010 photon setup to study real noisy channels. Skeptics highlight limits. Andreas Winter at the University of Cologne praised insights into feedback enhancing protocols but dismissed time travel. “As far as we know, time travel or signalling back in time is not possible in our world. We don’t know of any mechanism that would make it possible,” Winter said. The work appears in Physical Review Letters.