‘Interstellar’ inspired study proves it is possible to send messages back in time

Christopher Nolan's iconic film Interstellar has served as inspiration for a new study that analyses whether we can send messages to someone in the past. They noted that this is possible, but only a limited amount of information would be filtered through a noisy channel. Physicists from Cornell University and the Massachusetts Institute of Technology (MIT) collaborated and started from the scene where Cooper is sending messages to his daughter back in time after falling into a black hole. The team treated this scenario as math and found that this is not merely fiction. Researchers Kaiyuan Ji and Seth Lloyd have successfully calculated the exact mathematical limit of how many "bits" of data can reliably survive being sent through a noisy, imperfect backwards-time loop.

Defeating the Grandfather Paradox

What the scientists needed to get past was the Grandfather Paradox, which states that if an action in the past is changed because of a message from the future, then the message never really gets sent in the first place. The two created a self-consistent "causal loop" to fix this problem. In the past, the receiver stored a quantum-linked particle. Years later, the sender attaches a message to this receiver and uses a process called amplified probabilistic teleportation to send it. The quantum math filters out anything that erases its own cause and creates inconsistencies. The future loop itself automatically boosts the odds of the correct, non-paradoxical message arriving perfectly intact.

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Why the receiver comes first

While sending a letter, the sender writes it first, and the recipient gets it later. In this experiment, the quantum trick completely flips the order. The daughter takes a pair of quantumly linked particles, keeps half of the pair and puts it in storage, leaving a quantum hint waiting in the past. In the future, the father retrieves that stored quantum particle and links it to the actual message he wants to send. This forces the quantum loop to lock into place. In this case, the receiver comes first, already leaving a hint. The sender picks up that hint and makes sure the loop fits perfectly.

The main question the paper tries to answer is how many bits the backward channel can carry. How well the information is saved, and how much is corrupted, are the two quantities. The noisier channels carry less information, and the formula created by the scientists shows how much less. This math has a massive impact on understanding black holes. The "black hole information paradox" has been a source of debate for decades, and for the first time, this new formula gives scientists a concrete tool to calculate exactly how much information could escape a collapsing black hole.