SCIENCE
The Secret Life of The Universe
Nathalie A. Cabrol
Simon & Schuster, $34.99

Nathalie Cabrol is an extraordinary woman. Not only is she director of the Carl Sagan Centre at the SETI (Search for Extraterrestrial Intelligence) Institute, she holds the world record for high-altitude freediving (in a Bolivian lake atop the 6000-metre volcano Licancabur), and was the NASA geologist who selected the 2004 Spirit rover’s landing site on Mars.

Cabrol’s engrossing exploration is subtitled An astrobiologist’s search for the origins and frontiers of life, and she takes a hands-on approach. She wasn’t diving into the frigid waters of that volcanic lake for fun, but in search of “extremophiles”, or life that can survive in the most hostile conditions. She found it, too.

Despite her job title, Cabrol’s book is only partly about the search for intelligent life in other worlds. Much of Secret Life is devoted to tracking down the most extreme extremophiles. The really hardy ones that just might be sharing our solar system with us, hiding under the rocks of Mars, floating in the clouds of Venus, and swimming under the ice of the moons of Jupiter and Saturn.

But why stop there? Her search widens to the planets orbiting other stars – the first of which was only discovered in 1992 – now known to number in the thousands, and probably billions. Cabrol’s book is a wonderful celebration of the corollary to the Copernican revolution, whereby humanity finally acknowledged that Earth is not the centre of the universe. If this is true in astronomy, which it undoubtedly is, then why not biology?

Philosophers, writers and dreamers have been populating other worlds with exotic creatures for centuries, but actual evidence of life beyond our atmosphere has been non-existent so far. Well, until recently. No, we have not found alien civilisations with faster-than-light travel and the Wisdom of the Ages, and nor are we likely to. Basic physics renders such a meeting wildly unlikely.

Chemistry and the laws of probability, on the other hand, are our friends in all this. The chemical composition of the universe, at its current age of around 13 to 14 billion years, is dictated by what has been going on in stars since the Big Bang. As they burn hydrogen into helium, and then heavier elements, the big ones eventually explode, creating all the elements up to uranium. These stellar ashes then form nebulae: clouds that gradually coalesce and accrete into other stars and, it is now known for certain, planets. Not only do these planets amount to untold expanses of real estate for potential residents, they all contain, to varying degrees, the key elements to form what Cabrol describes as “the building blocks of life”.

In the famous 1952 Miller-Urey experiment, a rough guess was made of the composition of the Earth’s early atmosphere, likely gases combined in a flask, and jolted with electricity to mimic ancient lightning. The resulting goop contained amino acids – the most basic of Cabrol’s “building blocks”. Amino acids are the key ingredients of proteins, and proteins are essential for creating cellular, self-replicating living things. Of course, it’s a long leap from stinky gunk in a ’50s lab flask to DNA and the plays of Shakespeare, but it’s a start.