杏吧原创

FUNDAMENTAL physics is in a funk. Its guiding programme, to explain things by inventing ever more particles, has stalled, leaving 95.4 per cent of the stuff in the universe 鈥� the provinces of dark matter and dark energy 鈥� unexplained. What is more, the underlying theory of microscopic reality that physics serves up, quantum theory, presents reality in a form no one can get their heads round. Oh, and quantum theory doesn鈥檛 play ball with the other big theory of modern physics, Einstein鈥檚 general relativity.

Ah yes, Einstein: one way or another, you can鈥檛 dodge the web he created. In seeking new answers to the age-old question of what space and time are (see 鈥�What is space-time? The true origins of the fabric of reality鈥�), theoretical physicist Sean Carroll has to confront Einstein鈥檚 legacy of an interwoven, highly malleable space-time that underlies general relativity. With delicious irony, Carroll鈥檚 new ideas invoke a brainchild of Einstein, but one he invented to be disowned: quantum entanglement, derided by Einstein as 鈥渟pooky action at a distance鈥�.

Einstein was both general relativity鈥檚 progenitor and quantum theory鈥檚 greatest critic. History may show whether neither, one or both of his sets of ideas were right. In the meantime, the nature of space and time seems as good a place to start as any to begin sorting out what鈥檚 what. Physics works by the minimisation of mysteries, and their current multiplication suggests that whatever we鈥檝e got wrong, it is something pretty fundamental.

Carroll is far from alone in scratching around this ball park. Recently in these pages, theorist Lee Smolin detailed his work that comes to similar conclusions, albeit from the very different starting point of trying to explain quantum theory鈥檚 ineffability (24 August). Zoom further out from the realms of physics, and cognitive scientist Donald Hoffman鈥檚 ideas suggest that space and time are just powerful evolutionary illusions (3 August).

Whether any of these ideas are right or indeed necessary remains to be seen. But remember, similar concerns swirled around Einstein鈥檚 ideas at the time.