Back to the Future

Why is it easy to break an egg, but impossible to un-break it? More generally, why is the past so different from the future? We can’t travel into the past, but we’re inexorably carried into the future. We can remember the past, but we can’t reliably predict the future. But strangely, the fundamental laws of physics work just as well backwards as forwards – so why do we perceive an arrow of time? That’s the subject of my new feature article for BBC Earth….

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Where were all of the things a long time ago? Can we find out by looking at things now?

Some of my friends and I use big computers to try to find out where stuff was — all of the stuff, in every place out in space — in the first tiny part of a second, at the beginning of time. We do this by looking at where all of the stuff in space is now, and trying to guess what that means about where stuff was before. But it is very hard to do that, even with a big computer….

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