Richard Dawkins - The Magic of Reality: How We Know Whats Really True

About the Book

Magic takes many forms. The ancient Egyptians explained the night by suggesting that the goddess Nut swallowed the sun. The Vikings believed a rainbow was the gods bridge to earth. These are magical, extraordinary tales. But there is another kind of magic, and it lies in the exhilaration of discovering the real answers to these questions. It is the magic of reality science.

Packed with inspiring explanations of space, time and evolution, laced with humour and clever thought experiments, The Magic of Reality explores a stunningly wide range of natural phenomena. What is stuff made of? How old is the universe? What causes tsunamis? Who was the first man, or woman? This is a page-turning, inspirational detective story that not only mines all the sciences for its clues but primes the reader to think like a scientist too.

Richard Dawkins elucidates the wonders of the natural world to all ages with his inimitable clarity and exuberance in a text that will enlighten and inform for generations to come.

C ONTENTS

Clinton John Dawkins
19152010
O, my beloved father

W HAT IS REALITY?
W HAT IS MAGIC?

REALITY IS EVERYTHING that exists. That sounds straightforward, doesnt it? Actually, it isnt. There are various problems. What about dinosaurs, which once existed but exist no longer? What about stars, which are so far away that, by the time their light reaches us and we can see them, they may have fizzled out?

Well come to dinosaurs and stars in a moment. But in any case, how do we know things exist, even in the present? Well, our five senses sight, smell, touch, hearing and taste do a pretty good job of convincing us that many things are real: rocks and camels, newly mown grass and freshly ground coffee, sandpaper and velvet, waterfalls and doorbells, sugar and salt. But are we only going to call something real if we can detect it directly with one of our five senses?

What about a distant galaxy, too far away to be seen with the naked eye? What about a bacterium, too small to be seen without a powerful microscope? Must we say that these do not exist because we cant see them? No. Obviously we can enhance our senses through the use of special instruments: telescopes for the galaxy, microscopes for bacteria. Because we understand telescopes and microscopes, and how they work, we can use them to extend the reach of our senses in this case, the sense of sight and what they enable us to see convinces us that galaxies and bacteria exist.

How about radio waves? Do they exist? Our eyes cant detect them, nor can our ears, but again special instruments television sets, for example convert them into signals that we can see and hear. So, although we cant see or hear radio waves, we know they are a part of reality. As with telescopes and microscopes, we understand how radios and televisions work. So they help our senses to build a picture of what exists: the real world reality. Radio telescopes (and X-ray telescopes) show us stars and galaxies through what seem like different eyes: another way to expand our view of reality.

Back to those dinosaurs. How do we know that they once roamed the Earth? We have never seen them or heard them or had to run away from them. Alas, we dont have a time machine to show them to us directly. But here we have a different kind of aid to our senses: we have fossils, and we can see them with the naked eye. Fossils dont run and jump but, because we understand how fossils are formed, they can tell us something of what happened millions of years ago. We understand how water, with minerals dissolved in it, seeps into corpses buried in layers of mud and rock. We understand how the minerals crystallize out of the water and replace the materials of the corpse, atom by atom, leaving some trace of the original animals form imprinted on the stone. So, although we cant see dinosaurs directly with our senses, we can work out that they must have existed, using indirect evidence that still ultimately reaches us through our senses: we see and touch the stony traces of ancient life.

In a different sense, a telescope can work like a kind of time machine. What we see when we look at anything is actually light, and light takes time to travel. Even when you look at a friends face you are seeing them in the past, because the light from their face takes a tiny fraction of a second to travel to your eye. Sound travels much more slowly, which is why you see a firework burst in the sky noticeably earlier than you hear the bang. When you watch a man chopping down a tree in the distance, there is an odd delay in the sound of his axe hitting the tree.

Light travels so fast that we normally assume anything we see happens at the instant we see it. But stars are another matter. Even the sun is eight light-minutes away. If the sun blew up, this catastrophic event wouldnt become a part of our reality until eight minutes later. And that would be the end of us! As for the next nearest star, Proxima Centauri, if you look at it in 2012, what you are seeing is happening in 2008. Galaxies are huge collections of stars. We are in one galaxy called the Milky Way. When you look at the Milky Ways next-door neighbour, the Andromeda galaxy, your telescope is a time machine taking you back two and a half million years. Theres a cluster of five galaxies called Stephans Quintet, which we see through the Hubble telescope spectacularly colliding with each other. But we see them colliding 280 million years ago. If there are aliens in one of those colliding galaxies with a telescope powerful enough to see us, what they are seeing on Earth, at this very moment, here and now, is the early ancestors of the dinosaurs.

Are there really aliens in outer space? Weve never seen or heard them. Are they a part of reality? Nobody knows; but we do know what kind of things could one day tell us if they are. If ever we got near to an alien, our sense organs could tell us about it. Perhaps somebody will one day invent a telescope powerful enough to detect life on other planets from here. Or perhaps our radio telescopes will pick up messages that could only have come from an alien intelligence. For reality doesnt just consist of the things we already know about: it also includes things that exist but that we dont know about yet and wont know about until some future time, perhaps when we have built better instruments to assist our five senses.

Atoms have always existed, but it was only rather recently that we became sure of their existence, and it is likely that our descendants will know about many more things that, for now, we do not. That is the wonder and the joy of science: it goes on and on uncovering new things. This doesnt 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. We should always be open-minded, but the only good reason to believe that something exists is if there is real evidence that it does.

Models: testing our imagination

There is a less familiar way in which a scientist can work out what is real when our five senses cannot detect it directly. This is through the use of a model of what might be going on, which can then be tested. We imagine you might say we guess what might be there. That is called the model. We then work out (often by doing a mathematical calculation) what we ought to see, or hear, etc. (often with the help of measuring instruments) if the model were true. We then check whether that is what we actually do see. The model might literally be a replica made out of wood or plastic, or it might be a piece of mathematics on paper, or it might be a