The Science of Discworld (Science of Discworld, #1)

by Terry Pratchett

Dragons don’t breathe fire because they’ve got asbestos lungs – they breathe fire because everyone knows that’s what dragons do.

To a scientist, a thought experiment is an argument that you can run through in your head, after which you understand what’s going on so well that there’s no need to do a real experiment, which is of course a great saving in time and money and prevents you from getting embarrassingly inconvenient results.

Sometimes, the best answer is a more interesting question.)

Many of them also have a thoroughgoing grounding in ‘common sense’, one of science’s natural enemies.

PPS Sometimes scientists change their minds. New developments cause a rethink. If this bothers you, consider how much damage is being done to the world by people for whom new developments do not cause a rethink.

Wizards can put up with any amount of deprivation and discomfort, provided it is not happening to them.

‘Wasn’t Stanmer Crustley the one who died of planets?’

The early stages of education have to include a lot of lies-to-children, because early explanations have to be simple.

There are little questions, there are medium-sized questions, and there are big questions. After which there are even bigger questions, huge questions, and questions so vast that it is hard to imagine what kind of response would count as an answer.

Beware of scientific fundamentalists who try to tell you everything is pretty much worked out, and only a few routine details are left to do. It is just when the majority of scientists believe such things that the next revolution in our world-view creeps into being, its feeble birth-squeaks all but drowned by the earsplitting roar of orthodoxy.

our narrativium-powered semantics confuses us. This does not mean that if you went back 15 billion and one years, you would find nothing. It means that you cannot go back 15 billion and one years. That description makes no sense. It refers to a time before time began, which is logically incoherent, let alone physically so.

The evidence in favour of the Big Bang is twofold. The first item is the discovery that the universe is expanding. The second is that ‘echoes’ from the Big Bang can still be detected today.

Enter Edwin Hubble, an American astronomer. Hubble was observing distant stars, and he made a curious discovery. The further away the stars were, the faster they were moving.

The Holy Grail of particle physics has been to find the ‘Higgs boson’, which – if it exists – explains why the other particles have mass. In the 1960s Peter Higgs suggested that space is filled with a kind of quantum treacle called the Higgs field. He suggested that this field would exert a force on particles through the medium of the Higgs boson, and that force would be observed as mass.

‘It could have been anything at all, sir. Even a stray thought. Absolute nothing is very unstable. It’s so desperate to be something.’

If you built a guillotine, and then put a sign on it saying ‘Do Not Put Your Neck On This Block’, many wizards would never have to buy a hat again.

Piles of sand try to look like mountains. Men try to act like gods. Little things so often appear to look like big things made smaller. Our new universe, gentlemen, will do its crippled best to look like ours. We should not be surprised to see things that look hauntingly familiar. But not as good, obviously.’

For a while, the atom was pictured as being rather like a tiny solar system, with the nucleus playing the role of the sun and the electrons orbiting it like planets. However, this model didn’t work very well – for example, an electron is a moving charge, and according to classical physics a moving charge emits radiation, so the model predicted that within a split second every electron in an atom would radiate away all of its energy and spiral into the nucleus. With the kind of physics that developed from Isaac Newton’s epic discoveries, atoms built like solar systems just don’t work. Nevertheless, this is the public myth, the lie-to-children that automatically springs to mind. It is endowed with so much narrativium that we can’t eradicate it.

‘Will you two stop shouting!’ yelled the Senior Wrangler. Two student wizards were arguing vehemently, or at least repeatedly stating their point of view in a loud voice, which suffices for argument most of the time.

As a general rule, he avoided getting to know the students, since he felt they were a tedious interruption to the proper running of college life.

Science is not about building a body of known ‘facts’. It is a method for asking awkward questions and subjecting them to a reality-check, thus avoiding the human tendency to believe whatever makes us feel good.

space and time are to some extent interchangeable.

Ponder Stibbons was an atheist. Most wizards were. This was because UU had some quite powerful standing spells against occult interference, and knowing that you’re immune from lightning bolts does wonders for an independent mind.

Storytelling is the opposite of reductionism; 26 letters and some rules of grammar are no story at all.

This seems to promote the human mind to a special status – it has even been suggested that our purpose in the universe is to observe it, thereby ensuring its existence, an idea that the wizards of UU consider to be simple common sense. Schrödinger, however, thought this was silly, and in support he introduced a thought experiment now called Schrödinger’s Cat. Imagine a box, with a lid that can be sealed so tightly that nothing, not even the barest hint of a quantum wavelet, can leak out. The box contains a radioactive atom, which at some random moment will decay and emit a particle, and a particle detector that releases poison gas when it detects the atom decaying. Put the cat in the box and close the lid. Wait a bit. Is the cat alive or dead? If the atom has decayed, then the cat’s dead. If not, it’s alive. However, the box is sealed, so you can’t observe what’s inside. Since unobserved quantum systems are waves, the quantum rules tell us that the atom must be in a ‘mixed’ state – half decayed and half not. Therefore the cat, which is a collection of atoms and so can be considered as a gigantic quantum system, is also in a mixed state: half alive, half dead. In 1935 Schrödinger pointed out that cats aren’t like that. Cats are macroscopic systems with classical yes/no physics. His point was that the Copenhagen interpretation does not explain – or even address – the link from microscopic quantum physics to macroscopic classical physics. The Copenhagen interpretation replace...

When silicon and oxygen combine together, you get silicates – rocks.

It also seems likely that huge numbers of planets exist without a central star.

The biggest dream of all, though, is NASA’s Planet Imager, pencilled in for 2020.

computer simulations show that 50 telescopes with a baseline of just 95 miles (150 km) can produce images of a planet 10 light years away that are good enough to spot continents and even moons the size of ours.

The current favourite for life in the solar system is a surprise, at least to people who don’t read science fiction: Jupiter’s satellite Europa.

‘Autopoeisis’ – the ability to make chemicals and structures related to one’s own reproduction – is not a bad definition, except that modern life has evolved away from those early necessities.

‘hypercanes’ – like hurricanes but with a windspeed close to that of sound.

Indeed, some people think that the greatest threat to humanity is not global warming, but an incipient ice age. How ironic, and how undeserved, if our pollution of the planet cancels out a natural disaster!

explaining to one another, now that the impossible had happened, that of course it had been inevitable.

It was probably the strangest cry of warning since the famous ‘Should the reactor have gone that colour?’

Life was on land. According to the book, there should be some big lizards. But nothing seemed to be making much of an effort. The moment anything felt safe, it stopped bothering.

‘You’ve been interfering again, haven’t you,’ Ridcully went on. ‘I saw you pushing some of the small lizards out of that tree.’ ‘Well, you’ve got to admit that they look a bit like birds,’ said the Dean. ‘And did they learn to fly?’ ‘Not in so many words, no. Not horizontally’

The great biologist John (J.B.S.) Haldane was once asked what question he would like to pose to God, and replied that he’d like to know why He has such an inordinate fondness for beetles.*1 There are a third of a million beetle species today – far more than in any other plant or animal group.

The moral of this tale is that we should not look for ‘the’ cause of the dinosaur extinction. It is very rare for there to be just one cause of a natural event, unlike scientific experiments which are specially set up to reveal unique explanations.

Significantly, no one has made a film bringing back dodos, moas, pygmy elephants, or mosasaurs – only dinosaurs and Hitler are popular for the reawakening myth. Both at the same time would be a good trick.

In the past, the environment was a context for us – we evolved to suit it. Now we’ve become a context for the environment – we change it to suit us.

In 2001, to test that claim, John Alroy simulated the effect of hunting in computer models of 41 North American species. It turned out that extinctions were virtually unavoidable, especially for the larger animals. Even highly incompetent hunters would have wiped them out. The simulations correctly ‘postdicted’ the fate of 32 of the 41 species, which adds credibility to their conclusions. ‘Whodunnit?’ New Scientist asked, offering its own suggestion: ‘Mr Sapiens in the Americas with a large axe.’

by the time humans were able to articulate the term ‘natural environment’, there wasn’t one. We had changed the face of continents,

Australia alone has over a hundred species of marsupials – in fact most native Australian mammals are marsupials. Another seventy or so are found in the same general region

Joel Best pointed out in his book Damned Lies and Statistics in 2001,

the surfing apes theory has to take second place

DNA studies indicate that the two chimp species diverged about 60,000 Grandfathers ago – three million years. Humans and chimps diverged 80,000 Grandfathers earlier – so a chain of only 140,000 grandfathers unites you and your chimplike ancestor.

an entire eye can evolve in a mere 8,000 Grandfathers

there is nothing in the environment of the evolving mind that can drive it towards self-complication – becoming more sophisticated – unless that brain has something else fairly sophisticated to interact with.

Samuel R. Delany in the novel Empire Star.