The Forbidden Universe (30 page)

One can hardly imagine a more nihilistic worldview than that expressed by another theoretical physicist and Nobel Prize-winner, Steven Weinberg: ‘The more the universe seems comprehensible, the more it also seems pointless.’
⁴

Of course, Carr and Rees were emphatically not claiming that they had found scientific evidence for the existence of God. They were highlighting a question that science had largely avoided, having only been explored by a handful such as Carter, and then only tentatively. The anthropic principle merely makes the observation that life could never have arisen except under very specific conditions, and does not necessarily propose that they were put in place
in order
to produce life. The assumption behind Carr and Rees’ paper was that what looks like design is really an illusion based on our human-centred perception of the cosmos: if the laws of physics were any different there would be no life to ponder this question in the first place. After all, just because we live on a habitable planet, it doesn’t mean that the planet was created especially for us.

But they admitted that the odds were far too high to dismiss all the examples of apparent fine-tuning as coincidence. Some other, unknown, factor had to explain
the illusion. As they concluded after surveying the many conditions that seemed so convincingly contrived:

Perhaps this situation can be explained using the analogy of a lottery: if we win, we might ascribe our success to our skill in picking the numbers or believe we were somehow ‘meant’ to win, but in fact our triumph would be entirely due to chance. Much the same, the anthropic principle shows that the odds seem to have been stacked in life’s favour, as if after scooping the jackpot we found that only our own numbers had been put into the machine.

Although the overwhelming majority of scientists believe that the rigging of the universal lottery machine can be explained purely in terms of an illusion – the ‘weak anthropic principle’ – there are some who ascribe to the ‘strong anthropic principle’, which stipulates that the universe is the way it is specifically to give rise to intelligent life. Among them is Freeman Dyson, the British-born American theoretical physicist, who wrote in 1979:

In fact, the apparent fine-tuning of the universe involves so many factors that it is not merely the equivalent of winning the lottery once. This is scooping the jackpot week after week for several years.

The classic example of the fine-tuning is the origin of carbon, one of the most abundant elements in the universe, which is essential for the existence of life (as in the familiar phrase ‘carbon-based life forms’), at least as far as we can conceive it. Like all but the very simplest elements, carbon is manufactured in the centre of stars, the only places hot enough, at several million degrees, to allow the nuclear fusion that, in a literal transmutation, builds the atoms of one element from those of others. At the beginning of the 1950s, scientists understood the principle behind the formation of carbon, but not precisely how the process worked, as there seemed to be an insurmountable obstacle. Although an atom of carbon is made from the fusion of the nuclei of three atoms of helium, this should be an extraordinarily rare event, as first
two
helium nuclei had to fuse, and the resultant structure (an atom of beryllium) is so unstable it should be impossible for it to survive long enough for a third nuclei to join the act. If carbon managed to exist at all, it should be a very rare element, whereas of course the universe is actually overflowing with it. Clearly, some kind of special condition exists that increases the chances of the three helium nuclei coming together.

In 1951 a British astronomer, the celebrated – and to some, notorious – scientific maverick Fred (later Sir Fred) Hoyle, speculated that the solution to the mystery
surrounding
carbon was that the nucleic energy is enormously amplified by an aspect of quantum theory called resonance. This would prolong the life of the beryllium and so greatly increase the chances of the third helium nuclei joining the
party. From this premise, Hoyle was then able to calculate what the energy of the resonance ought to be. An American team at the California Institute of Technology (Caltech), the only place at that time where such experiments could be carried out, tested Hoyle’s prediction and found he had been precisely correct. This was a watershed event in the modern history of science, marking an enormous leap in the understanding of the way all elements are created. But while the American team were honoured with a Nobel prize for the discovery, blunt Yorkshireman Hoyle was overlooked (as we will see in the next chapter), almost certainly because by the time the prizes were awarded in the mid-1980s, Hoyle had championed two controversies too far – the theory of panspermia, the idea that life came to Earth from space, and that of the ‘intelligent universe’.

What really intrigued Hoyle was the precision of the energy ‘spike’ produced by the resonance, known as the triple-alpha process. If it were just one per cent higher or lower the reaction would fail, ultimately leaving only tiny amounts of carbon in the universe, and therefore no life. As there seemed no reason for the resonance to be so precise
except
to make the process work, Hoyle went so far as to describe it as a ‘put-up job’.
⁷

The significance of the triple-alpha process goes beyond the creation of carbon, since all other elements necessary for life depend on it. Stellar ‘factories’ work by adding nuclei to the atoms of one element to make a new, more complex, one. Just as beryllium atoms have to form before carbon can be made, so carbon atoms are needed to make oxygen, oxygen atoms to make neon, and so on. All these reactions are more straightforward than the triple-alpha process as they don’t require the convenient energy spike, so the obstacle Hoyle faced isn’t present. But if carbon did not exist, then neither would any of the elements above it on the periodic table. Literally everything depends on the
triple-alpha process. Without it there would only be four elements in the entire universe.

Such apparent contrivances prompted Hoyle to declare in a lecture at University Church, Cambridge, in 1957:

Since Hoyle made that statement, the more science has discovered about the origins and evolution of the universe the more ‘monstrous’ the ‘sequence of accidents’ has become.

One of the first to be intrigued by Brandon Carter’s anthropic principle was British cosmologist Paul Davies – that rare animal, both a highly regarded academic and a successful popular science writer. He has continued to explore the implications and mysteries of the anthropic principle, most famously in
God and the New Physics
(1983) and
The Mind of God
(1992), and most recently in
The Goldilocks Enigma
(2006) – the title referring to the conditions in the universe that are, like Goldilocks’ porridge, ‘just right’ for life.

Davies points out that life has three main requisites: ‘stable complex structures’ in the universe (galaxies, stars and planets rather than clouds of gas or vast numbers of black holes); certain chemical elements (for example carbon, oxygen); and a place where the components can come together (for example the surface of a planet). Of course our
universe has all of these components, but each requires such fortuitous circumstances to exist that ours is, as Davies puts it, apparently a ‘designer universe’.
⁹

The universe as it is today is, of course, the result of how it was in the beginning. Had conditions been different then, it would be different now – and almost certainly hostile to the development of life. According to today’s thinking, the universe began 13.7 billion years ago with the ‘big bang’. (Ironically the term was invented by the sceptical Hoyle, but only as a put-down. Then to compound the irony, his team found some of the best supporting evidence for it.) The big bang had to be within a certain range of size and explosive potential to produce our universe. If it had been bigger or bangier, it would have expanded too quickly for galaxies to form. If it had been smaller or less bangy, gravity would have pulled the universe back into itself well before life could have evolved.

For a time after the big bang the expanding universe was too hot to be anything other than a dense, incandescent plasma composed of subatomic particles like protons, neutrons and electrons. As it expanded further it cooled, so that – an estimated 380,000 years after the big bang – the particles could fuse to form the simplest elements, hydrogen and helium. Those two elements make up about 99 per cent of matter in the universe. But if the relative masses of protons, electrons and neutrons were only minutely different, not a single hydrogen atom could form. It seems we must boldly go well beyond the frontiers of coincidence to begin to understand the way our universe was created, and how it continues to work.

Attracted by the gravity of individual atoms, clouds of hydrogen and helium clump together, clumping faster and faster as they grow. The smaller the clumps, the hotter they become, until they are hot enough to kick-start nuclear reactions – and it is at this stage that a star is born, whose
deadly beauty masks its true self, a gigantic fusion reactor. Acting as unimaginably massive factories that manufacture more complex elements from hydrogen and helium, stars then disperse these into space where they explode as supernovae. Every atom in every molecule, including those that make us up, was born in a star light years away, millions or billions of years ago, making even the tiniest newborn in some respects old beyond imagining. As the legendary American theoretical physicist Richard P. Feynman observed, ‘the stars are of the same stuff as ourselves’.
¹⁰
And as Paul Davies comments:

But contrived and intertwined by whom or what?

There are also many instances where a combination of factors has to work together to produce a bio-friendly outcome – almost as if knobs are being twiddled until the balance is exactly right. In his 1999 book
Just Six Numbers
, Bernard Carr explored six of the fundamental forces, or relationships between forces, on which the universe is built. He found that all of them are very finely balanced, and if they were just slightly smaller or larger they wouldn’t produce a life-friendly universe. As he pointed out in 2008:

Stephen Hawking also acknowledges this remarkable phenomenon:

Perhaps the most astonishing example of fine-tuning comes from the most recent to be discovered. In order to describe it, we need to start from the apparently bizarre premise that there is no such thing as ‘empty’ space; even the interstellar vacuum is filled with ‘virtual particles’ that nevertheless possess energy. This has an effect on the rest of the universe, specifically on the rate at which it is expanding. In theory at least, the ‘vacuum energy’ has huge potential significance in terms of the anthropic principle. Some of the particles will be positive, some negative. If the sum total of all the vacuum energy were positive, then the expansion of the universe would be accelerating, and if it were above a certain value then the universe would have expanded too fast for galaxies to form – matter would fly apart faster than gravity could pull it together. On the other hand, if the vacuum energy were negative, the life cycle of the universe – from big bang to big crunch – would be too short for life to evolve.