What's happening?

Nora finds herself in a library where every book tells the story of her life differently. In one she is an Olympic medallist; in another she is a rock star. She can live any of these lives simply by opening the right book.

This is what happens in Matt Haig's book The Midnight Library. It explores the idea that every choice we make leads to a different version of the universeEverything. Including all of time and space and its contents. .

This began with a debate among Christians about the world God put us in. The 18th Century thinker Gottfried Wilhelm Leibniz said that we live in "the best of all possible worlds".

Now, scientists have taken the idea of multiple worlds further.

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Experiments show that basic units of light can be both particles and waves at the same time. Some scientists now argue that our world has many possible variations.

One form of this belief suggests that somewhere out there lives another version of you, your house and your family - but you have brown hair instead of red.

Many writers and film-makers have been inspired by the idea of multiple worlds - including the maker of the latest Spider-Man film.

Yes! If multiple worlds exist, we can spend ages thinking about the better choices we might be making in other lives. This is going to cause unhappiness.

No! It is amazing to know that things we have dreamed about could actually be true in a different world.