We are a product of evolution, and are not surprised that our bodies seem to be well-suited to the environment.
Our leg bones are strong enough to allow for Earth’s gravitational pull – not too weak to shatter, not so massively over-engineered as to be wasteful.
But it could also be claimed we are special and the environment was formed and shaped for us.
This, as we know, is the basis of many religious ideas.
In recent years, such ideas have been expanded beyond Earth to look at the entire universe and our place within it.
The so-called Fine-Tuning Argument – that the laws of physics have been specially-tuned, potentially by some Supreme Being, to allow human life to arise – is the focus of Victor J. Stenger’s book.
Stenger presents the mathematics underpinning cosmic evolution, the lifetime of stars, the quantum nature of atoms and so on. His central is that “fine-tuning” claims are fatally flawed.
He points out that some key areas of physics – such as the equality of the charges on the electron and proton – are set by conservation laws determined by symmetries in the universe, and so are not free to play with.
Some flaws in the theory, he argues, run deeper.
A key component of the fine-tuning argument is that there are many parameters governing our universe, and that changing any one of these would likely produce a sterile universe unlike our own.
But think of baking a cake. Arbitrarily doubling only the flour, or sugar or vanilla essence may end in a cooking disaster, but doubling all the ingredients results in a perfectly tasty cake.
The interrelationships between the laws of physics are somewhat more complicated, but the idea is the same.
A hypothetical universe in which gravity was stronger, the masses of the fundamental particles smaller and electomagnetic force weaker may well result in the following: a universe that appears a little different to our own, but is still capable of producing long-lived stars and heavy chemical elements, the basic requirements for complex life.
Stenger backs up such points with his own research, and provides access to a web-based program he wrote called MonkeyGod.
The program allows you to conjure up universes with differing underlying physics. And, as Stenger shows, randomly plucking universe parameters from thin air can still produce universes quite capable of harbouring life.
This book is a good read for those wanting to understand the fine-tuning issues in cosmology, and it’s clear Stenger really understands the science.
But while many of the discussions are robust, I felt that in places some elements of the fine-tuning argument were brushed aside with little real justification.
As a case in point, Stenger falls back on multiverse theory and the anthropic principle, whereby we occupy but one of an almost infinite sea of different universes, each with a different law of physics.
In multiverse theory, most universes would be sterile (though we should not be surprised to find ourselves in a habitable universe).
While such a multiverse – the staple of superstring and brane ideas of the cosmos – is often sold as science fact, it actually lies much closer to the world of science speculation (or, to many, fiction).
We are not out of the fine-tuning waters yet, but Stenger’s book is a good place to start getting to grips with the issues.
For more such insights, log into www.international-maths-challenge.com.
*Credit for article given to Geraint Lewis*