What if our two best hopes for a theory of everything turn out to be the same? Jon Cartwright pulls at the threads
AS THE bell rings for the final round, both fighters are in their corners. The heavyweight champion is panting, against the ropes. The underdog is sprawled on the opposite side, bruised, tired but determined.
Everyone is expecting an exhilarating finale. The challenger has put on a good show, landing a few square punches. Admittedly, it was accused of cheating by ignoring the rules of physics. But that was nothing compared with the favourite’s big trick: dancing in seven invisible dimensions.
This is no ordinary fight: it’s for the honour of successfully explaining the fundamental make-up of the universe. The heavyweight incumbent is string theory, a complex construct that has long had pretensions to be “theory of everything”. The upstart contender, loop quantum gravity, has more modest aspirations – but could still change the face of physics as we know it.
Physicists have long believed they must pin their hopes on just one contender. But as the two rivals walk back into the ring, there’s a turn-up for the books: they reach out for a handshake. If the latest indications are right, it seems the two theories are not so different after all. They might in fact be the same theory in disguise – with implications that reach far and wide. “The next revolution in physics is going to come from people who can cross the boundary,” says Laurent Freidel, a theorist at the Perimeter Institute in Waterloo, Canada. […]
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