Farewell to Reality (43 page)

Rees' sixth number is the simplest of the set. It is
the number of spatial dimensions (not including ‘hidden' dimensions demanded by superstring/M-theory). There are no one- or two-dimensional complex biological entities, simply because complex biology demands a minimum of three dimensions. And a value of
of 3 is the only number compatible with the inverse-square laws of gravity and electromagnetism.

The paranoia runs deep. Virtually everywhere we turn we're faced with an apparently phenomenal fine-tuning of the universe's physical constants and laws. If the weak force were stronger or weaker, then the primordial abundances of hydrogen and helium would have been very different, and subsequent stellar nucleosynthesis would not have produced the ingredients needed to sustain life. If the mass of the neutron wasn't slightly larger than the proton … And so on and on.

In the fairy tale, Goldilocks finds that baby bear's porridge is just the right temperature, that baby bear's chair is just the right size and that baby bear's bed has just the right softness. And what happens when we put human beings (or, at the very least, the possibility of biology) back into the picture? We find that the universe is not ‘just right', it appears extraordinarily fine-tuned for life.

This is the Goldilocks enigma.

The weak anthropic principle

Although there have been many examples of ‘anthropic' reasoning throughout history, the notion of an anthropic principle was first introduced by the Australian theorist Brandon Carter. Whilst studying for his PhD at Cambridge University in 1967, Carter had become absorbed by the challenge of understanding the origin of the numerical coincidences that seem to dominate cosmology and physics. Influenced by Wheeler at Princeton, he circulated lecture notes on the subject informally among colleagues, eventually publishing his ideas in 1974.

Carter intended the anthropic principle as a direct challenge to the Copernican Principle. He presented his arguments at an International Astronomical Union symposium in Cracow on 10—12 September 1973. The conference had been dedicated to commemorate the five hundredth anniversary of Copernicus' birth.

Whereas the Copernican Principle insists that intelligent life occupies no privileged position in the cosmos, the anthropic principle suggests that our status as conscious observers of our universe
demands
at least some form of privileged perspective.

Carter offered two versions. The first is the
weak anthropic principle:
‘we must be prepared to take account of the fact that our location in the universe is necessarily privileged to the extent of being compatible with our existence as observers'.
³

This seems like common sense, if a bit of a tautology. In essence, it is a statement that relates to the notion of
observer self-selection.
The universe we observe must, by definition, include observers like us capable of observing it. Our observations are necessarily biased by virtue of our own existence. We are (again, by definition) unable to observe a universe in which observers like us cannot exist.

In Carter's definition, the word ‘privileged' is used in a relatively mild sense. This is entirely compatible with the notion that intelligent observers are a perfectly natural phenomenon. No matter how improbably the physical universe appears to be fine-tuned and no matter how unlikely the facts of biological evolution through natural selection, the bottom line is that we're here.

Now, the key question is what — if anything — the weak anthropic principle has to say about the
reason
we're here. One argument is that we're here because, by happy accident or the operation of some complex natural physical mechanisms we have yet to fathom, the parameters of the universe just happen to be compatible with our existence.

In this argument, intelligent life remains a
consequence
of the nature and structure of our universe (it is therefore I am). But it leaves us in the rather unsatisfactory position of having no real explanation under present understanding as to precisely
why
the universe is the way it is.

Maybe you can already sense where this is leading. If we have no explanation for the fine-tuning of the universe, perhaps this is because the universe isn't really fine-tuned after all. What if the universe we inhabit is but one of an infinite or near-infinite number of parallel universes in which all manner of different combinations of physical parameters are possible?

In most of these universes the parameters are incompatible with the existence of intelligent life. The operation of selection bias means that, no matter how atypical or improbable the parameters of the universe we find ourselves in, we shouldn't be surprised to find that this is nevertheless precisely the universe we observe.

The anthropic multiverse

Carter used the weak anthropic principle to argue for the existence of what he called an
ensemble
of universes — meaning simply that there are many (maybe an infinite number) — without specifying precisely what these were or where they might have come from. There are many different possibilities, some of which were discussed in Chapter 9. Readers interested in a more comprehensive review of the different multiverse theories should consult Brian Greene's
The Hidden Reality.

Of course, this is the reason why the anthropic principle has become so popular among theorists in recent years. It shouldn't come as any real surprise that those theorists who favour the cosmic landscape of superstring/M-theory's 10
⁵⁰⁰
different ways of constructing a universe have rushed to embrace anthropic reasoning.

What I find quite remarkable is that the observer selection bias summarized in the anthropic principle is sometimes used as a kind of
justification
for landscape theories, as though it were an important piece of observational evidence in support of them! The logic runs: the fact that our universe seems highly improbable
must
mean that observer selection bias is operating in a multiverse of possibilities.

The relationship is mutual. The landscape is also used to lend credibility to the anthropic principle, as Susskind claims: ‘Whether we like it or not, this is the kind of behavior that gives credence to the anthropic principle.'
⁴

Although this marriage between the landscape and anthropic logic might initially have been rather forced, it does seem to be a marriage made in heaven. In
The Cosmic Landscape,
Susskind writes:

Until very recently, the anthropic principle was considered by almost all physicists to be unscientific, religious, and generally a goofy misguided idea. According to physicists it was a creation of inebriated cosmologists, drunk on their own mystical ideas … But a stunning reversal of fortune has put string theorists in an embarrassing position: their own cherished theory is pushing them right into the waiting arms of the enemy … The result of the reversal is that many string theorists have switched sides.
⁵

The strong anthropic principle

Carter's second version of the anthropic principle is the
strong anthropic principle:
‘the Universe (and hence the fundamental parameters on which it depends) must be such as to admit the creation of observers within it at some stage'.
⁶

In this definition the key word is ‘must', and one (somewhat irresistible) interpretation restores intelligent life to its pre-Copernican, fully privileged status. The strong anthropic principle tips us towards teleology — philosophical positions that perceive ultimate purposes,
final causes and deliberate design in nature. It puts ‘us' firmly back at the centre of the picture.

To be fair to Carter, both his weak and strong anthropic principles were based on the notion of intelligent observers, not necessarily carbon-based life forms like ourselves. He later regretted his use of the word ‘anthropic'.

But the cat was out of the bag. When theorists John Barrow and Frank Tipler popularized the principle in their book
The Anthropic Cosmological Principle,
first published in 1986, they made no bones about making both the weak and strong versions all about carbon-based life forms. This was a carefully constructed scholarly survey of the literature on the subject, and although Barrow and Tipler did not argue for any particular position, they extended the principle into some highly speculative, extreme versions and helped to muddy the waters considerably.

The argument from design

The strong form of the anthropic principle drags us into some highly contentious and emotionally charged territory.

There's a good chance that, having made it this far, you're a reader who happens to be interested in what contemporary science is saying about the nature of the physical world around us. You've hopefully taken the trouble to absorb the six Principles presented in Chapter 1, and whether you agree with them or not, I would assume you're reasonably clear in your own mind about what science is, broadly speaking.

I'm hoping that we can therefore agree that intelligent design is not science.

Intelligent design is a variation of ‘creation science' (a non-sequitur if ever there was one). As an idea it has a relatively long history, but its modern form was developed by a group of American creationists and is today most closely associated with a non-profit organization called the Discovery Institute, founded in 1990 and based in Seattle, Washington. The institute promotes a number of projects across a range of areas. In the field of science and culture, its website declares its agenda as follows:

Scientific research and experimentation have produced staggering advances in our knowledge about the natural world, but they have also led to increasing abuse of science as the so-called ‘new atheists' have enlisted science to promote a materialistic worldview, to deny human freedom and dignity and to smother free inquiry. Our Center for Science and Culture works to defend free inquiry. It also seeks to counter the materialistic interpretation of science by demonstrating that life and the universe are the products of intelligent design and by challenging the materialistic conception of a self-existent, self-organizing universe and the Darwinian view that life developed through a blind and purposeless process.
⁷

Okay, so we're clear about that.

The Discovery Institute's ambition to get intelligent design taught in science classes alongside Darwin's theory of evolution by natural selection led in 2005 to the landmark case of Tammy Kitzmiller et al. vs Dover Area School District et al., which was heard in a US district court in Pennsylvania. Conservative Republican Judge John E. Jones III ruled that intelligent design is
not
science. A Dover school board decision to oblige its staff to teach intelligent design was ruled to be unconstitutional. In a subsequent school board election, the eight board members who had voted for this decision were ousted.

When I was young, I thoroughly enjoyed the 1960 film
Inherit the Wind,
starring Spencer Tracy and Frederic March as protagonists locked in a courtroom debate about the teaching of evolution in an American school. The film was based on the 1955 play by Jerome Lawrence and Robert Edwin Lee, which was itself an accurate fictional account of the 1925 trial of John Thomas Scopes in Dayton, Tennessee. Scopes stood ‘accused' of teaching the theory of evolution. He was found guilty and fined $100, but the verdict was subsequently overturned following an appeal to the Supreme Court.

I had imagined that these kinds of courtroom battles were things of history. When I first heard about the Dover School case, eighty years after the Scopes trial, I was utterly shocked. Yes, these were two very different cases. In the first, it was Darwin in the dock. In the second, it was intelligent design. But at stake in both cases was the notion that religious or theistic beliefs should
not
inform efforts to understand the ‘truths' of our physical, chemical and biological world. I had assumed that
such a notion was by now self-evident in civilized societies and that there had long since ceased to be a case to answer, either way. I was wrong.