— How We Know What’s Really True
Select Quotes
Chapter 1: What Is Reality? What Is Magic?
Stephan’s Quintet, – Page 11
For reality doesn’t just consist of the things we already know about: it also includes things that exist but that we don’t know about yet and won’t know about until some future time, perhaps when we have built better instruments to assist our five senses. – Page 11
That is the wonder and the joy of science: it goes on and on uncovering new things. This doesn’t mean we should believe just anything that anybody might dream up: there are a million things we can imagine but which are highly unlikely to be real–fairies and hobgoblins, leprechauns and hippogriffs. – Page 11
We come to know what is real, then, in one of three ways. We can detect it directly, using our five senses; or indirectly, using our senses aided by special instruments such as telescopes and microscopes; or even more indirectly, by creating models of what might be real and then testing those models to see whether they successfully predict things that we can see (or hear, etc.), with or without the aid of instruments. – Page 14
Supernatural magic is the kind of magic we find in myths and fairy tales. (In ‘miracles’, too, though I shall leave those to one side for now and return to them in the final chapter.) It’s the magic of Aladdin’s lamp, of wizards’ spells, of the Brothers Grimm, of Hans Christian Andersen and of J. K. Rowling. It’s the fictional magic of a witch casting a spell and turning a prince into a frog, or a fairy godmother changing a pumpkin into a gleaming coach. These are the stories we all remember with fondness from our childhood, and many of us still enjoy when served up in a traditional Christmas pantomime–but we all know this kind of magic is just fiction and does not happen in reality. – Page 15
Indeed, to claim a supernatural explanation of something is not to explain it at all and, even worse, to rule out any possibility of its ever being explained. Why do I say that? Because anything ‘supernatural’ must by definition be beyond the reach of a natural explanation. It must be beyond the reach of science and the well-established, tried and tested scientific method that has been responsible for the huge advances in knowledge we have enjoyed over the last 400 years or so. To say that something happened supernaturally is not just to say ‘We don’t understand it’ but to say ‘We will never understand it, so don’t even try.’ – Page 17
It would be relatively easy to turn something complicated like a coach into something simple–like ash, for instance: the fairy godmother’s wand would just need a built-in blowtorch. It is easy to turn almost anything into ash. But no one could take a pile of ash–or a pumpkin–and turn it into a coach, because a coach is too complicated; and not just complicated, but complicated in a useful direction: in this case, useful for people to travel in. – Page 18
this deal is no more unlikely than every other deal of cards that has ever happened! The chance of any particular deal of 52 cards is 1 in 53,644,737,765,488,792, 839,237,440,000 because that is the total number of all possible deals. It is just that we don’t notice any particular pattern in the vast majority of deals that are made, so they don’t strike us as anything out of the ordinary. We only notice the deals that happen to stand out in some way. – Page 20
The magic of reality is neither supernatural nor a trick, but–quite simply–wonderful. Wonderful, and real. Wonderful because real. – Page 26
Chapter 2: Who Was The First Person?
Quite often we meet different versions of the same myth. That’s not surprising, because people often change details while telling tales around the camp fire, so local versions of the stories drift apart. – Page 29
Every picture shows a creature belonging to the same species as the picture on either side of it. – Page 33
A baby changes into a toddler, then into a child, then into an adolescent; then a young adult, then a middle-aged adult, then an old person. And the change happens so gradually that there never is a day when you can say, ‘This person has suddenly stopped being a baby and become a toddler.’ – Page 33
Chapter 3: Why Are There So Many Different Kinds Of Animals?
To a fish, a lake is an island. – Page 55
Next time you see an animal–any animal–or any plant, look at it and say to yourself: what I am looking at is an elaborate machine for passing on the genes that made it. I’m looking at a survival machine for genes. Next time you look in the mirror, just think: that is what you are too. – Page 63
Chapter 4: What Are Things Made Of?
A diamond crystal is a huge molecule, – Page 67
We have to realize that what we feel and see as solid matter is more than just nuclei and electrons–the ‘footballs’ and the ‘gnats’. Scientists talk about ‘forces’ and ‘bonds’ and ‘fields’, which act in their different ways both to keep the ‘footballs’ apart and to keep the components of each ‘football’ together. And it is those forces and fields that make things feel solid. – Page 74
Even they contain yet smaller things, called quarks. But that is something I’m not going to talk about in this book. That’s not because I think you wouldn’t understand it. It is because I know I don’t understand it! We are here moving into a wonderland of the mysterious. And it is important to recognize when we reach the limits of what we understand. It is not that we shall never understand these things. Probably we shall, and scientists are working on them with every hope of success. But we have to know what we don’t understand, and admit it to ourselves, before we can begin to work on it. There are scientists who understand at least something of this wonderland of the very small, but I am not one of them. – Page 78
It wasn’t until the microscope was invented in the sixteenth century that people discovered that ponds and lakes, soil and dust, even our own bodies, teem with tiny living creatures, too small to see, yet complicated and, in their own way, beautiful–or perhaps frightening, depending on how you think about them. – Page 80
Chapter 5: Why Do We Have Night And Day, Winter And Summer?
‘I suppose because it looked as if the sun went round the Earth.’ ‘Well,’ Wittgenstein replied, ‘what would it have looked like if it had looked as if the Earth turned on its axis?’ – Page 87
Chapter 6: What Is The Sun?
4 But the nearest other star, Proxima Centauri, to the same scale, would be another (slightly smaller) football located about … wait for it … six and a half thousand kilometres away! – Page 106
Chapter 7: What Is A Rainbow?
We often find that seemingly ancient legends have come from even older legends, usually with some names or other details changed. – Page 123
Chapter 8: When And How Did Everything Begin?
None of the myths gives any explanation for how the creator of the universe himself (and it usually is a he) came into existence. – Page 136
The wave travels at a fixed speed, regardless of whether the source of the sound is a trumpet or a speaking voice or a car: about 768 miles per hour in air (four times faster under water, and even faster in some solids). – Page 146
Chapter 9: Are We Alone?
As I said, myths about aliens in this sense are rare among primitive tribes. They are all too common, however, among modern city dwellers. These modern myths are interesting because, unlike ancient myths, we can actually watch as they start. We see myths being dreamed up before our very eyes. – Page 150
There is a whole mythology of ‘alien abductions’, which is as rich, as colourful and as detailed as the mythology of ancient Greece and the gods of Mount Olympus. – Page 152
Now, if you are going to have a hallucination when you suffer sleep paralysis, what might that hallucination look like? A modern science fiction fan might well see little grey men with big heads and huge eyes. In earlier centuries, before science fiction came along, the visions people saw were different: hobgoblins, perhaps, or werewolves; bloodsucking vampires or (if they were lucky) beautiful winged angels. – Page 153
Is there really life on other planets? Nobody knows. If you forced me to give an opinion one way or the other, I’d say yes, and probably on millions of planets. But who cares about an opinion? There is no direct evidence. One of the great virtues of science is that scientists know when they don’t know the answer to something. They cheerfully admit that they don’t know. – Page 155
Chapter 10: What Is An Earthquake?
Terrible as earthquakes can be, the wonder is that they aren’t even more terrible. – Page 179
Chapter 11: Why Do Bad Things Happen?
It is hard to resist this feeling that, somehow, there ought to be a kind of natural justice. – Page 182
‘The good ended happily, and the bad unhappily. That is what fiction means.’ – Page 182
The truth, of course, is that there is noise going on most of the time, but we only notice it when it is an irritation, as when it interferes with filming. There is a bias in our likelihood of noticing annoyance, and this makes us think the world is out to annoy us deliberately. – Page 186
That is the true sense in which ‘everything happens for a reason’, the sense in which ‘reason’ means ‘past cause’. But people sometimes use reason in a very different sense, to mean something like ‘purpose’. They will say something like ‘The tsunami was a punishment for our sins’ or ‘The reason for the tsunami was to destroy the strip clubs and discos and bars and other sinful places.’ – Page 188
Child psychologists have shown that very young children, when asked why certain rocks are pointy, reject scientific causes as an explanation and prefer the answer: ‘So that animals can scratch themselves when they get itchy.’ Most children grow out of that kind of explanation for the pointy rocks. But quite a lot of adults seem unable to shake off the same kind of explanation when it comes to major misfortunes like earthquakes, or good fortune such as lucky escapes from earthquakes. – Page 188
For just the same reason, it is complete nonsense to think you can improve your luck by wearing a lucky charm around your neck. Or by crossing your fingers behind your back. These things have no way of influencing what happens to you unless it is by some effect on how you feel: giving you added confidence that calms your nerves before a tennis serve, for example. – Page 190
The universe has no mind, no feelings and no personality, so it doesn’t do things in order to either hurt or please you. Bad things happen because things happen. Whether they are bad or good from our point of view doesn’t influence how likely it is that they will happen. – Page 191
Nobody is suggesting that the spider or the ant lion is ingenious–that it has thought up its cunning trap. But natural selection makes them evolve brains that behave in ways that look ingenious to our eyes. In the same way, a lion’s body looks ingeniously designed to bring about the doom of antelopes and zebras. And we can imagine that, if you were an antelope, a stalking, chasing, pouncing lion might seem out to get you. – Page 192
those individual animals that act as though Sod’s Law were true are more likely to survive and reproduce than those individual animals that follow Pollyanna’s Law. – Page 193
Chapter 12: What Is A Miracle?
The key point is that we only bother to tell stories when strange coincidences happen–not when they don’t. Nobody ever says, ‘Last night I dreamed about that uncle I haven’t thought of for years, and then I woke up and found that he hadn’t died in the night!’ – Page 203
There was a famous Scottish thinker in the eighteenth century called David Hume who made a clever point about miracles. He began by defining a miracle as a ‘transgression’ (or breaking) of a law of nature. Walking on water, or turning water into wine, or stopping or starting a clock by the power of thought alone, or turning a frog into a prince, would be good examples of breaking a law of nature. Miracles like that would be very disturbing indeed to science, for the reasons discussed in the chapter on magic. Disturbing if they ever happened, that is! So how should we respond to stories of miracles? This was the question Hume turned to; and his answer was the clever point I mentioned. If you want to know Hume’s actual words, here they are, but you have to remember that he wrote them more than two centuries ago, and English style has changed since then. No testimony is sufficient to establish a miracle, unless the testimony be of such a kind, that its falsehood would be more miraculous than the fact which it endeavours to establish. Let’s put Hume’s point into other words. If John tells you a miracle story, you should believe it only if it would be even more of a miracle for it to be a lie (or a mistake, or an illusion). – Page 205
Which of these possibilities do you think is the most plausible? All three of them seem pretty unlikely. But surely Possibility 3 is the least far-fetched, the least deserving of the title of miracle. To accept Possibility 3 we only have to believe that somebody told a lie in reporting that 70,000 people saw the sun move, and the lie got repeated and spread around, just like any of the popular urban legends that whizz around the internet nowadays. Possibility 2 is less likely. It requires us to believe that 70,000 people simultaneously experienced a hallucination involving the sun. Rather far-fetched. But however unlikely–almost miraculous–Possibility 2 may seem, even that would be far less of a miracle than Possibility 1. – Page 209
There are things that not even the best scientists of today can explain. But that doesn’t mean we should block off all investigation by resorting to phoney ‘explanations’ invoking magic or the supernatural, which don’t actually explain at all. – Page 215
If something happens that appears to be inexplicable by science, you can safely conclude one of two things. Either it didn’t really happen (the observer was mistaken, or was lying, or was tricked); or we have exposed a shortcoming in present-day science. If present-day science encounters an observation, or an experimental result, that it cannot explain, then we should not rest until we have improved our science so that it can provide an explanation. If it requires a radically new kind of science, a revolutionary science so strange that old scientists scarcely recognize it as science at all, that’s fine too. It’s happened before. But don’t ever be lazy enough–defeatist enough, cowardly enough–to say ‘It must be supernatural’ or ‘It must be a miracle’. Say instead that it’s a puzzle, it’s strange, it’s a challenge that we should rise to. Whether we rise to the challenge by questioning the truth of the observation, or by expanding our science in new and exciting directions, the proper and brave response to any such challenge is to tackle it head-on. And, until we have found a proper answer to the mystery, it’s perfectly OK simply to say, ‘This is something we don’t yet understand, but we’re working on it.’ – Page 216