The Science of Discworld Revised Edition

very bright, bodies called quasars. They found subtle changes in certain features of that light, called spectral lines, which are related to the vibrations of various types of atom. In effect, what they seem to have discovered is that many billion years ago – much further back than the Oklo reactor – atoms didn’t vibrate at quite the same rate as they do today. In very old gas clouds from the early universe, the fine structure constant differs from today’s value by one part in 50,000. That’s a
huge
amount by the standards of this particular area of physics. As far as anyone can tell, this unexpected result is not due to experimental error. A theory suggested in 1994 by Thibault Damour and Alexander Polyakov does indicate a possible variation in the fine structure constant, but only one-ten thousandth as large as that found by Webb’s team.
    In 2001 another team led by John Webb analysed the absorption of light from distant quasars by clouds of interstellar gas, and announced that the fine structure constant has increased by one hundred thousandth since the Big Bang. This result, if true, implies that the gravitational, weak nuclear, and strong nuclear forces have all changed over time. The work is being checked for possible systematic errors, which might produce the same observations.
    It’s all a bit of a puzzle, and most theorists sensibly prefer to hedge their bets and wait for further research. But it could be a straw in the wind: perhaps we will soon have to accept that the laws of physics were subtly different in the distant reaches of time and space. Not turtle-shaped, perhaps, but … different.
    1 Or at least, less radioactive. We can but hope.
    2 He was the victim of a magical accident, which he rather enjoyed. But you
know
this.
    3 They say that every formula halves the sales of a popular science book. This is rubbish – if it was true, then
The Emperor’s New Mind
by Roger Penrose would have sold one-eighth of a copy, whereas its actual sales were in the hundreds of thousands. However, just in case there is some truth to the myth, we have adopted this way of describing the formula to double our potential sales. You all know which formula we mean. You can find it written out in symbols on page 118 of Stephen Hawking’s
A Brief History of Time
– so if the myth is right, he could have sold twice as many copies, which is a mindboggling thought.
    4 The fine structure constant is defined to be the square of the charge of an electron, divided by 2 times Planck’s constant times the speed of light times the permittivity of the vacuum (as a handy lie, the last term might be thought as ‘the way it reacts to an electric charge’). Thank you.

THREE
I KNOW MY WIZARDS

    IT DID NOT take long for the faculty to put its collective finger on the philosophical nub of the problem,
vis-à-vis
the complete destruction of everything.
    ‘If no one will know if it happens, then in a very real sense it wouldn’t have happened,’ said the Lecturer in Recent Runes. His bedroom was on one of the colder sides of the university.
    ‘Certainly we wouldn’t get the blame,’ said the Dean, ‘even if it did.’
    ‘As a matter of fact,’ Ponder went on, emboldened by the wizards’ relaxed approach, ‘there is some theoretical evidence to suggest that it could not possibly happen, due to the non-temporal nature of the thaumic component.’
    ‘Say again?’ said Ridcully.
    ‘A malfunction would not result in an
explosion
exactly, sir,’ said Ponder. ‘Nor, as far as I can work out, would it result in things ceasing to exist from the present onwards. They would cease to have existed at all, because of the multidirectional collapse of the thaumic field. But since we
are
here, sir, we must be living in a universe where things did not go wrong.’
    ‘Ah, I know this one,’ said Ridcully. ‘This is because of quantum, isn’t it? And there’s some usses in some universe next door where it
did
go wrong, and the poor devils got blown up?’
    ‘Yes, sir. Or, rather, no. They didn’t get blown up because the device the other Ponder Stibbons would have built would have gone wrong, and so … he didn’t exist not to build it. That’s the theory, anyway.’
    ‘I’m glad that’s sorted out, then,’ said the Senior Wrangler briskly. ‘We’re here because we’re here. And since we’re here, we might as well be warm.’
    ‘Then we seem to be in agreement,’ said Ridcully. ‘Mr Stibbons, you may start