Two couriers leave the same city in opposite directions. An hour later, each opens an envelope: one contains a card marked “plus,” the other “minus.” How did they know which one they'd get? In the quantum world, such a pair is called entangled, and its particles behave exactly the same way: measuring one instantly determines the state of the other, even if they are kilometers apart.
Standard physics forbids superluminal signals, so the correlations of entangled particles are considered inexplicable. The author of a new paper proposes a model: the two couriers don't communicate directly; instead, they both call a hidden dispatch center located in a second time dimension. The signal travels there at a finite speed, but for us, living in a single time, the conversation looks instantaneous.
The model reproduces the standard correlations for an entangled pair: if one particle collapses into the “plus” state, the other collapses into “minus.” The key prediction is the appearance of similar correlations between particles from different pairs, if their detectors are closer to each other than to their own partners. This can be tested by measuring the parameter S in Bell's inequality: for independent particles, it should be no more than 2, while the model allows up to 2√2 ≈ 2.828.
For now, this is pure knowledge, with no applications in sight. But two couriers with envelopes are no longer just a trick: they might be a trace of a hidden tunnel through which nature sends messages faster than we can notice.
Extra temporal dimensions are usually avoided because of the 'grandfather paradox': time travel could allow you to kill your ancestor. The author sidesteps this by assuming that only the subquantum field lives in two times, while particles remain in one.