Purpose - A Design to Creation?
Any coincidence, said Miss Marple to herself, is always worth noting. You can throw it away later if it is only a coincidence.
Purpose is not something physics usually concerns itself with. It sees the Universe unfolding according to a pre-ordained set of laws. We may not understand all the laws, and even when we do we may not be able to predict exactly how things will behave -- as quantum physics and chaos theory have both made clear -- nonetheless being physical laws they leave no room for purpose. At least, not in the sense of striving towards a goal.
However, this is not the only sense in which things can have a purpose. There can also be purpose in design. A clock runs according to well-defined physical laws, but this does not mean it has no purpose. It was constructed and set running in such a way that its movements would have meaning. The question that some scientists are now beginning to ask is: Could the same be true of the Universe? Could it run according to the laws of physics, yet be set up to run in a particular direction, towards a particular end?
A Coincidental Universe?
The way the Universe operates is determined by various fundamental constants -- such as the masses of the atomic particles, the electric charge of an electron, and the strength of the gravitational force. Scientists used to think that if one of these constants were to be slightly different it might make a difference to the way the Universe behaved, but the Universe itself would still exist. Physicists are now realizing that this may not be so. It appears that if the conditions of the original creation were not exactly as they were the Universe would not have existed for very long, and life would never have had the chance to evolve.
Physicists believe that at the time of the Big Bang the number of particles created was very slightly greater than the number of anti-particles -- about one part in a billion more. Whenever particles and anti-particles meet they annihilate each other; and within a short time of the Big Bang all the anti-particles had met their match and disappeared -- along with a corresponding number of particles. But because of the initial inequality some matter remained. This matter became the Universe we know. Had it not been for this initial imbalance, there would have been no galaxies, no stars, no planets, nor even the simplest of chemical elements.
Moreover the total number of matter particles left over -- about 1080 (1 followed by 80 zeros) -- was also critical. If the number had been slightly greater the gravitational forces would have been stronger than the energy of expansion. The young Universe would have rapidly collapsed in upon itself to form one huge black hole.
Conversely, if the number had been slightly smaller, gravitational forces would have been weaker, and the Universe would have expanded so rapidly that galaxies would never have had time to form. Again, the Universe as we know it would not have existed.
Another factor crucial for the existence of matter was the mass of the neutron -- the particle that together with the proton forms atomic nuclei. If this were only 0.2 percent less than its actual value, protons would have rapidly decayed into neutrons and no atoms would ever have been formed.
The atoms that initially formed were those of hydrogen. However, before these could evolve into the second element, helium, there had to be some other lucky coincidences. If the nuclear force, which holds atomic nuclei together against their electromagnetic repulsion, were a few percent weaker, deuterium -- a stage that hydrogen passes through as it combines to form helium -- would have been very unstable. The Universe would have remained almost pure hydrogen.
If, on the other hand, the nuclear forces had been a few percent stronger all the hydrogen in the Universe would have burnt to helium in a matter of seconds. And with all the hydrogen gone there would have been no fuel for stars.
Before helium could evolve into other elements, such as carbon, oxygen, and nitrogen, another coincidence was necessary. The charge on the proton had to be just right. If it had been slightly larger the nuclei of these heavier atoms would not have been stable. They would have decayed rapidly leaving a Universe of only hydrogen and helium.
The further evolution of matter into elements heavier than iron had to wait for the first stars to complete their life cycle and turn into supernova, which released the additional energy that was needed for the synthesis of these larger atoms. But the fact that stars can reach this stage at all depends upon some other fine tunings. If the force of gravity were very slightly stronger, the electromagnetic force very slightly weaker, or the electron slightly less heavy, the convective processes within stars would have been very different. Most stars would have been unable to evolve beyond the stage of burning helium. They would never have reached the stage of supernova. And without supernova there would have been no heavy elements, and thus no possibility for life.
The Coincidence of Life
However, before life could begin, some other very fine tunings were necessary.
Life as we know it is based upon carbon. All the proteins, amino acids, vitamins, fats, and carbohydrates which make up your body are molecules built on a skeleton of carbon. It was once thought that life based on silicon, or even some other element, might also be possible; but it is now generally believed that only carbon offers the variety and complexity of bonds that living systems depend upon. Yet the very existence of carbon rests on a most precise and unusual coincidence involving a phenomenon known as nuclear resonance. I will not go into the details since they involve some more complex physics; put very simply, it determines the probability that a nucleus will capture and combine with the nucleus of another atom. It turns out that if the nuclear resonance level for carbon were not exactly the value it is, virtually no carbon would ever have formed inside stars, and the possibility of life would never have existed.
But this is only half the story. Once a carbon atom does form there is the possibility of it combining with a helium nucleus to form oxygen. Luckily, however, the nuclear resonance for oxygen lies just below the critical value; otherwise any carbon that did form would have rapidly disappeared -- again making life impossible. .
Not only are these two resonances a most remarkable pair of coincidences, they are themselves the result of some very fine tuning between the strengths of nuclear and electromagnetic interactions, along with the relative masses of electrons and protons.
And the list goes on.
The deeper one looks, the more it appears that the initial conditions of the cosmos, the strength of the bang, and the values of nature's fundamental constants were precisely those required to produce a physical Universe that was stable, that would evolve into a diversity of chemical elements and would eventually be able to sustain life.
The Anthropic Principle
How does one make sense of this remarkable collection of coincidences? Has some super-intelligence been at work adjusting the laws of physics in order to create the Universe the way it is? Or are they all just coincidences -- however remarkable?
Scientists attempts to answer such questions have given rise to what is known as The Anthropic Principle. In its most general form this states that the only Universe that can contain human beings (anthropos in Greek) -- and hence the only Universe that we can observe -- is one in which these coincidences are exactly as they are. If they were not, we would not be here to notice the fact.
It may sound simple, but the principle is open to some radically differing interpretations. What is known as the Weak Anthropic Principle falls very much in line with the conventional scientific paradigm, which excludes any notion of a grand design -- let alone any Grand Old Designer. It proposes that our very existence as human beings determines the type of Universe we can observe. It is not so much an accident that all the parameters are exactly as they are; it is an inevitability. We cannot possibly know of any other types of Universe, for we would not be around to observe them.
Some proponents of this view hold that there may in fact be numerous other Universes existing in parallel with our own. Others suggest there have been numerous Universes preceding ours and that numerous others are yet to follow. In each of these other Universes the fundamental constants might well be different. Only in a minute fraction of them -- probably less than one in a billion -- would the conditions be right for life to evolve. All others would be devoid of life, devoid of intelligent observers, and thus forever unknowable.
This, however, raises the question of whether or not an unknowable Universe can be said to exist. In an attempt to deal with this philosophical problem, and also to handle some of the stranger coincidences that are harder to explain by the Weak Anthropic Principle, cosmologists such as Fred Hoyle in England and John Wheeler in the U.S.A. have developed an alternative Strong Anthropic Principle. They argue that there can be no matter without an observer, for only when you make an observation do you convert the probability functions of quantum mechanics into actualities. Thus the only Universes that can exist are those that can be observed.
This implies that the initial conditions of any Universe must be such that:
1. The Universe can continue in a stable form
2. It continues long enough and with the right conditions for life to emerge
3. Life is able to evolve intelligent beings capable of observing the Universe.
In other words, the Universe exists so that it can be known.