Thursday, April 17, 2014

Thankfully, infinity isn't all it's cracked up to be

According to the many worlds hypothesis, there exists an infinite number of universes, and consequently anything that can happen has happened an infinite number of times.  So there's another universe in which I went to bed early tonight and didn't get round to writing this stuff … and yet another in which I omitted the commas from the previous sentence … and so on. Actually an infinite number in which I did each of those things, but lets skip over that absurdity as the proposition is already absurd without it.  It makes my brain explode, and I refuse to accept that this is the way reality is.

So how do we account for this state of affairs? Until recently only two possibilities presented themselves. The first of which was that the many worlds hypothesis is false. There's either only one universe or a finite number of them.  Now, physicists may indeed have got it wrong, but it's hardly my place to say so, as they’ve done the equations and I haven't, nor could I.   So we must consider a second possibility.

Namely that there's something wrong with my intellect. Evolution has simply failed to equip me with a brain capable of grasping the truth about reality. Well, that may be the case; but I refuse to accept it; perhaps indeed, because I've been given the wrong sort of brain; but I refuse to accept it nonetheless.

Mary Midgley: infinity not all it's cracked up to be. And a book that’s just come down from the shelf.
Thankfully the other day in New Scientist I came across a way out of this impasse: a third possibility, that there's something wrong with the idea of infinity.

On the letters page the philosopher Mary Midgley wrote about the meaning of “an infinity” of universes, which she asserts to signify a mere absence of known bounds. Our ignorance of limits is just a negative, she claims. As such, it cannot spawn new facts. In particular it can't spawn the new fact that "everything that can happen will happen, infinitely many times". In this sentence,  infinite is used in a different sense, this time meaning a very large number. This sort of thing is not philosophy, she says, it's just muddled language.

So hurrah. The physicists may be right about an infinite number of universes, but we've misconstrued the consequences of this. There isn't another me that omits commas, and I can accept the possibility of many universes without my head exploding.

There's a book on my shelf about infinity which I've never read.  I see that from the inscription that I bought it at Oxfam in York in 2006. A Brief History of Infinity – the Quest to Think the Unthinkable, by Brian Clegg, 2003.  It's off my shelf now. Time to tackle it.

A short note on many worlds if you want it.