Relative reading: "Quantum Theory Cannot Hurt You" by Marcus Chown

Tuesday, 2 November 2010

I was brought up to believe that there was nothing understandable that a normal person (i.e. for my purposes, me) could not understand, given sufficient effort. Hence my frustration that over the years I haven't been able to get my head around even the basics of quantum physics. There are people out there who are unlocking the secrets of the universe - the law of everything, so they say - and I don't get it. This makes me a sucker for those books which claim to explain it all in comprehensible layman's terms. Yes, I read the "Brief History of Time", and, I suspect like everyone else, understood almost nothing.

So when you happen across an inexpensive orange-coloured book, featuring child-like illustrations and big friendly letters saying "Quantum Theory Cannot Hurt You", it is difficult to resist, especially when the back cover blurb promises you "eureka moments" as you read it. The author, Marcus Chown, is a master of analogy, and seeks to explain the bizarrest of the bizarre in terms of what he describes as "ordinary world" experience. Trouble is, this is so far removed from ordinary experience that it has to break down sooner or later, and the insights you thought you might have been gaining all fall apart.

The book falls broadly into two sections, the first deals with the very small - the insides of atoms and the weird things you find there - while the second half takes on the very big - the universe, relativity and all that. If I got anything from the first half of the book, it is that everything is just unspeakably strange. For "particles" (for these are our protagonists, though we find that even that word is incredibly slippery, as matter and energy turn out to be just different aspects of the same thing), nothing is impossible. Being in two places at the same time? No problem. Time travel? Of course, do it all the time. Being mass and energy at the same time? C'mon, all the littl'uns do it...

After a while, one thing clicks. There is a thing called the "uncertainty principle", discovered (if that's the word) by a guy called Heisenburg in 1927. Yes, folks that's nineteen-twenty-seven! Which means that while 99.9% of the planet have been getting on with life, a tiny number of others have been doing this outlandish stuff for getting on for a century - and still no-one else gets it!

But back to the uncertinty principle. Here's how Wikipedia defines it:

In quantum mechanics, the Heisenberg uncertainty principle states by precise inequalities that certain pairs of physical properties, such as position and momentum, cannot be simultaneously known to arbitrarily high precision. That is, the more precisely one property is measured, the less precisely the other can be measured. The principle states that a minimum exists for the product of the uncertainties in these properties that is equal to or greater than one half of the reduced Planck constant (ħ = h/2π).

What it should be called, it seemed to me, is the "great let-off principle". The basic idea is that in quantum mechanics you cannot by definition precisely define the characteristics of a particle, at least not it's two most important properties, mass and velocity, at the same time. The more you know about one, the less you know - can know - about the other! So don't even try.

I think the point at which I got that was the point at which I stopped trying.

The second half of the book actually seemed (a bit) more approachable, maybe just because Einstein's general theory of relatively is even more venerable and is possibly more part of the general culture. Don't get the idea though that this is somehow straightforward. I didn't feel quite so irredeemably lost. One thing clicked: if the speed of light is fixed, at all times and in all circumstances (except for some especially dodgy particles, it seems), then everything else must be relative. Another thing sort of clicked: gravity is not some inexplicable force, but just an effect of the warping of space-time (don't ask me to elaborate). These are things I dimly saw, though I still don't think I could start to explain them.

Conclusion: maybe my liberal-humanist educational prejudices are wrong: there are things I will never get. But at least I have some greater understanding of why these are things I should not in any case normally be able to get.

Recommendation? Go on, have a go, you never know. Something tells me (perhaps it's that orange cover and big, friendly letters?) that if anyone can explain this stuff, it's Marcus Chown. But not to me, except possibly relatively speaking.

Big, friendly letters don't necessarily mean "eureka moments"