About ten years ago scientist Dave Bacon, now at Google, presented that a time-travelling quantum computer could rapidly solve a bunch of problems, known as NP-complete, which mathematicians have lumped together as being hard. The problem was, Bacon’s quantum computer was travelling around ‘closed timelike curves’. These are paths through the fabric of spacetime that loop back on themselves. General relativity lets such paths to exist through contortions in spacetime identified as wormholes.

Why send a message back in time, but lock it so that no one can ever read the contents? As it may be the key to resolving presently intractable problems. That’s the claim of an international collaboration.