Probably the most well-known scientific paradox is that of Schrodinger’s Cat, where those who adhere to the Copenhagen Interpretation of quantum mechanics would say that the hapless pussy is both dead and alive until the box in which it is enclosed is opened. This is the sort of perceived paradox which is only paradoxical until the underlying science is properly understood – in this case, the uncertainty seen in the quantum world decoheres when it is scaled up to the scale of the world we see (or alternatively, the ‘many worlds’ interpretation, as originated by Hugh Everett (father of Mark Oliver Everett, ‘E’ of Eels) would posit a branching into an alternate universe within the multiverse).
Al-Khalili dismissed rather rapidly the logical paradoxes such as ‘This statement is a lie’ as he finds them boring, and there’s not much you can say about them really, unless you’re a logician. I did do a course in mathematical logic many years ago and it was extremely boring – my best result was logically proving that all politicians are crocodiles, although I can’t now remember how I came to that conclusion.
The talk began properly, as does the book, with some apparent paradoxes from probability theory. Probability is often counter-intuitive, and difficult to grasp even when it’s explained well (several years ago there was an article in New Scientist which attempted to explain probability in some depth, but I was floundering by about half way through; there was a more understandable In Our Time on the subject in 2008). So we had a swift trip into the Monty Hall or Game Show Paradox; my favourite paradox of this type is the Birthday Paradox, which gets an explanation in the book.
We were shown how many of the historical so-called paradoxes were resolved as knowledge advanced (as an aside there’s an interesting article on the rate of change of knowledge in last week’s New Scientist): Zeno’s Achilles and the Tortoise, Olbers’ Paradox (first resolved by an unlikely person), and Maxwell and Laplace’s Demons.
The current major outstanding scientific puzzles such as whether we have free will, can a machine ever be conscious, why is there more matter than antimatter, what is dark matter made of, what is dark energy, and what was there before the Big Bang, tend to be just questions rather than paradoxes, although Laplace’s Demon has a direct bearing on the first of these.
The talk was rounded off with Fermi’s Paradox – where are all the aliens? This seemingly trivial question has deeper ramifications, not least regarding the anthropic principle, and subsequently the idea of a multiverse.
Jim Al-Khalili is always eminently listenable to, and although this sell-out lecture at the Royal Institution was quite light, and covered what, to me, were subjects I have previously heard or read in much greater depth, paradoxically I found the talk far too short.
I think the book’s an excellent introduction to the various subjects covered, although the chapters are a somewhat disparate bunch, the fact that they are (or were) paradoxes being the only common ground. A ‘further reading’ list wouldn’t have come amiss either.
His book Quantum: a guide for the perplexed is still, in my mind, his best book. Although the perplexity is deeper by the end of the book.