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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Seeing Strands in the Cosmic Web

For the first time, a part of the dark matter “skeleton” of the universe has revealed itself. The discovery strengthens our understanding of the universe’s history and tells us more about the formation of galaxies like our own, billions of years ago.

Current theories about the largest structures in the universe predict the existence of giant structures made of dark matter — the unseen substance that comprises over 80% of the matter in the universe — between most galaxy clusters. Now, for the first time, a team of cosmologists led by Jörg Dietrich at University Observatory Munich has found hard evidence that the long-sought-after strands of dark matter actually exist….

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