Reality check

Horizon (BBC2, Monday) asked, ‘What is reality?’ and didn’t really have an answer.

Horizon (BBC2, Monday) asked, ‘What is reality?’ and didn’t really have an answer. Well, it seems nobody does, though plenty of physicists, mathematicians and astronomers are working on it. As the voiceover told us, ‘Once you have entered their reality, your reality may never look the same.’ You can say that again. It appears that quantum particles can literally be in two places at the same time. But we are made up of quantum particles, and we are never in two places at the same time, even if that would occasionally be useful. So maybe there are more of us, all made up of the same particles but doing different things in different places. Possibly infinite numbers of us.

It was brave of the BBC. Particle physics, unlike cookery and wildlife, is not a natural for television. For a start, apart from chaps in beards, there isn’t much to look at, so we had lots of squiggles on blackboards, plus persons walking slowly and significantly across the Millennium Bridge.

Also, there were challenging lines, such as, ‘Is reality granular, and would that translate into ripples in the fabric of space-time?’ I’d like to see Cheryl Cole wrap her chops round that.

Even the anecdotes taxed the brain. Apparently, Einstein asked Niels Bohr, ‘Can you say that the moon is not there if nobody is looking at it?’ Bohr replied, ‘Can you prove the opposite?’ (I was reminded of the old philosophical conundrum: ‘How can you be sure that the train is leaving Paddington station and not that Paddington is leaving the train?’ Answer: you know when you reach Slough.) Apparently, Bohr might be right.