One way of making quantum mechanics independent of observers is to accept that we live in many parallel worlds.

Can the very act of observing something change what's being observed? This series of articles and videos explores some basic questions about the role of the observers in physics.

The possibility that there might be many parallel worlds has just become a little more likely.

Are there objective chances in the world?

Would you stake your fortune on a 100 to 1 outsider? Probably not. But what if, somewhere in a parallel universe, the straggling nag does come in first? Would the pleasure you feel in that universe outweigh the pain you feel in the one in which you've lost? Questions not dissimilar to this one occupy physicists and for entirely respectable reasons.

Are there parallel universes? Universes in which, rather than reading this article, you are still asleep; in which you are happier, unhappier, richer, poorer, or even dead? The answer is "possibly". It's a controversial claim but one that has won more and more followers over the last few decades.

Hugh Everett III is the father of the many-worlds interpretation of quantum mechanics. He published the idea in his PhD thesis but died before it gained the recognition it deserves. This article gives an insight into Everett's difficult life.

In the previous article we explored how a clever argument involving gambling makes the idea that there are parallel universes more credible. But does it really?

Are there parallel universes? In the latest online poll of our Science fiction, science fact project you told us that you'd like an answer to this question. So we spoke to physicists Adrian Kent and David Wallace to find out more. Happy reading!

In the first article of this series we introduced Schrödinger's equation and in the second we saw it in action using a simple example. But how should we interpret its solution, the wave function? What does it tell us about the physical world?