9781422283363

WHERE DOES THE T IME GO? Whenever you do something you have to use a different piece of time. You can’t reuse time as you can a ruler or a book. You may be able to run a race in 20 seconds, but every time you do it you use a different 20 seconds. The time you use has gone forever and you can never get it back. If you could use the same time again and again you would never get any older. Imagine if time was like distance and you could walk back to your sixth birthday!

Time seems only to go in one direction. You would think it very strange if your watch started to run backwards, or plants grew back into the ground,

or a broken plate mended itself. WHEN DID I T HAPPEN? So there are things we can do with time and there are ways we can measure it. But we still don’t know what it is.

What do all those bits of time—seconds, hours, years—actually mean? If you say to someone, “I’ll meet you in an hour,” what are you really saying?

We only see time going one way—into the future. It would appear very odd indeed if a rotten apple suddenly became fresh again.

You mean that you’ll be there when the minute-hand on your watch has gone right round once, because that is what an hour is. But an hour can be other things as well. It can be the time it takes for a fast train to go 100 miles (160 km) or your heart to beat about 4,500 times. What you are really saying is that something happens and it takes what we call an hour. If nothing happened anywhere, would time still pass? How could you possibly know that it had? Many people have wondered if there would be any time at all if absolutely nothing was happening anywhere. Perhaps time is just things happening and can’t exist on its own. You may think you have a good idea of what time is all about, but the world of time can be a strange one. Some people think that time can run backwards, and that it may be possible, although very difficult, to travel in time. Perhaps after you read this book you will begin to see that the apparently simple question, “What time is it?”’ isn’t so easy to answer after all.

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