The Universe Next Door: twelve mind-blowing ideas from the cutting edge of science by Marcus Chown

A parallel universe where science is actually fun
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People who do not care for science sometimes complain that it is too confining. They hear the scientist as a finger-wagging pedant, telling us why perpetual motion machines won't work, ley lines are fanciful or telepathy is out of bounds.

Useful physical laws always rule some things out. But, as Marcus Chown shows in this exuberant book, they also leave scope for enough weirdness to satisfy any taste for the bizarre. Maybe not telepathy, but time reversal, parallel universes, wandering planets and more.

Anyone who has already delved into the physics of the last 100 years – especially relativity and quantum theory – knows that the universe is pretty strange. Chown goes beyond established science to find still stranger notions. And by rounding up a whole slew of speculations that, however off-the-wall, are compatible with what we already know, he offers a beguiling portrait of science as creative play.

Any of these ideas can set the imagination working in new ways. Some – like the possibility that regions of the universe exist in which the arrow of time is reversed, or of infinitely many parallel universes or extra dimensions – are not new, though still pretty arresting if you take them seriously. How would you deal with a single life if you were really convinced that innumerable other versions of you were enjoying every alternative life you might dream of?

Others, which admittedly have fewer adherents, will be news to most readers. The idea that the vast bulk of our universe's mass is locked up inside fridge-sized black holes, and that we can observe their effects, gives astronomy a whole new interest. Or take the suggestion that, under special conditions in a vat of super-cooled liquid helium, the wave function of an electron might be split into two. Would this mean that the electron itself – that supposedly indivisible elementary particle – becomes two half-electrons? At least one respectable physicist thinks so.

There's more. Forget those parallel universes for a minute. There might also be a "mirror universe", made of stuff that does not normally interact with ordinary matter. That one depends on a speculation about the consequences of an aspect of particle theory, and some minute discrepancies between theory and observation in the behaviour of a toy atomic system that couples an electron and a positron.

Far less out on the fringes of theory, there are good reasons to think there may be myriad planets, ejected from newly formed solar systems, floating freely between the stars. You can even make an argument that, under a few more or less plausible assumptions, they might harbour life.

The image that conjures up is for me the most memorable in the book: unknown organisms, sustained by radioactive heat, clinging to the surface of planets voyaging through endless dark. But every reader will have some favourite from the novelties on offer. Like some of the other ideas – the origin of life in interstellar space, or the construction of new universes by ultra-intelligent beings – this one begins to shade into science fiction. But all the possibilities that Chown outlines are rooted in respectable theory. They may not be true, but they are not out of the question. All have at least one proponent who believes fervently that the idea is worth pursuing scientifically.

Some of these intrepid souls will no doubt fall foul of the dictum of the DNA pioneer Francis Crick that the trick to being a good theorist is not having good ideas, but being prepared to keep throwing them away and having new ones. But if you are not too bothered which of the ideas are true, they are certainly entertaining. Another great British biologist, JBS Haldane, once declared that the universe "is not only queerer than we suppose, but queerer than we can suppose". On the evidence here, some scientists are having a pretty good try at matching real with imaginary queerness.

The reviewer teaches science communication at University College London