Anthropic arrogance


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Claims that the Universe is designed for humans raise far more troubling questions than they can possibly answer

Welcome to the ‘anthropic principle’, a kind of Goldilocks phenomenon or ‘intelligent design’ for the whole Universe. It’s easy to describe, but difficult to categorise: it might be a scientific question, a philosophical concept, a religious argument – or some combination. The anthropic principle holds that if such phenomena as the gravitational constant, the exact electric charge on the proton, the mass of electrons and neutrons, and a number of other deep characteristics of the Universe differed at all, human life would be impossible. According to its proponents, the Universe is fine-tuned for human life.

This raises more than a few questions. For one, who was the presumed cosmic dial-twiddler? (Obvious answer, for those so inclined: God.) Second, what’s the basis for presuming that the key physical constants in such a Universe have been fine-tuned for us and not to ultimately give rise to the hairy-nosed wombats of Australia, or maybe the bacteria and viruses that outnumber us by many orders of magnitude? In Douglas Adams’s antic novel The Hitchhiker’s Guide to the Galaxy (1979), mice are ‘hyper-intelligent pan-dimensional beings’ who are responsible for the creation of the Earth. What if the Universe isn’t so much anthropic as mouse-thropic, and the appearance and proliferation of Homo sapiens was an unanticipated side effect, a ‘collateral benefit’?

For a more general perspective, in The Salmon of Doubt (2002), Adams developed what has become known as the ‘puddle theory’:

[I]magine a puddle waking up one morning and thinking, ‘This is an interesting world I find myself in – an interesting hole I find myself in – fits me rather neatly, doesn’t it? In fact it fits me staggeringly well, must have been made to have me in it!’

It appears that Adams favoured a puddle-thropic principle. Or at least, the puddle did.

But perhaps I should be more serious about an idea that has engaged not just theologians and satirists but more than a few hard-headed physicists. The Australian astrophysicist Brandon Carter introduced the phrase ‘anthropic principle’ at a conference in Krakow, Poland in 1973 celebrating the 500th anniversary of the birth of Copernicus. Copernicus helped evict the Earth – and thus, humanity – from its prior centrality, something that the anthropic principle threatens (or promises) to re-establish. For Carter, ‘our location in the Universe is necessarily privileged to the extent of being compatible with our existence as observers’. In other words, if the Universe were not structured in such a way as to permit us to exist and, thus, to observe its particular traits, then – it should be obvious – we wouldn’t be around to marvel at its suitability for our existence!

In A Brief History of Time (1988), the late British physicist Stephen Hawking described a number of physical constants and astrophysical phenomena that seem at least consistent with the anthropic principle. Hawking noted that ‘if the rate of expansion one second after the Big Bang had been smaller by even one part in a hundred thousand million million, the Universe would have recollapsed before it ever reached its present size’. In short, a change so small it challenges the imagination, and the Big Bang would have turned into a kind of Big Crunch.

Albert Einstein considered the ‘cosmological constant’, which he introduced in 1917, his ‘biggest blunder’. Considering the emergence of the anthropic principle, however, it seems prescient. Einstein was troubled by the fact that gravity would cause the Universe to collapse onto itself (that Big Crunch), so he surmised a constant – essentially out of thin air – that pulled in the opposite direction, causing the cosmos to remain stable. The American physicist Steven Weinberg – not a religious believer – points out that if this now-confirmed constant were just a smidgeon larger, the Universe would be vaporously insubstantial. It would never have stopped expanding at a rate that precludes the formation of galaxies, never mind planets or mammals such as ourselves.

In 1961, providing even more fodder for the anthropic principle, the American physicist Robert Dicke noted that the age of the Universe reflects a kind of Goldilocks principle. Dicke suggested that, at an estimated 14.5 billion years of age, our Universe stands at a ‘golden interval’, neither too young nor too old, but just right.

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