The flexi-laws of physics

Published by Paul Davies on 30/06/2007
New Scientist Magazine issue 2610

SCIENCE WORKS because the universe is ordered in an intelligible way. The most refined manifestation of this order is found in the laws of physics, the fundamental mathematical rules that govern all natural phenomena. One of the biggest questions of existence is the origin of those laws: where do they come from, and why do they have the form that they do?

Until recently this problem was considered off-limits to scientists. Their job was to discover the laws and apply them, not inquire into their form or origin. Now the mood has changed. One reason for this stems from the growing realisation that the laws of physics possess a weird and surprising property: collectively they give the universe the ability to generate life and conscious beings, such as ourselves, who can ponder the big questions.

If the universe came with any old rag-bag of laws, life would almost certainly be ruled out. Indeed, changing the existing laws by even a scintilla could have lethal consequences. For example, if protons were 0.1 per cent heavier than neutrons, rather than the other way about, all the protons coughed out of the big bang would soon have decayed into neutrons. Without protons and their crucial electric charge, atoms could not exist and chemistry would be impossible.

Physicists and cosmologists know many such examples of uncanny bio-friendly "coincidences" and fortuitous fine-tuned properties in the laws of physics. Like Baby Bear's porridge in the story of Goldilocks, our universe seems "just right" for life. It looks, to use astronomer Fred Hoyle's dramatic description, as if "a super-intellect has been monkeying with physics". So what is going on?

A popular way to explain the Goldilocks factor is the multiverse theory. This says that a god's-eye-view of the cosmos would reveal a patchwork quilt of universes, of which ours is but an infinitesimal fragment. Crucially, each patch, or "universe", comes with its own distinctive set of local by-laws. Maybe the by-laws are assigned randomly, as in a vast cosmic lottery. It is then no surprise that we find ourselves living in a patch so well suited to ...