7

The Quintessential

For 20 centuries and more deduction of the place of God and man in the universe was an accepted, even an expected, activity of physici. Perhaps the last significant expression of this corporate responsibility occurred in England around the middle of the nineteenth century in eight volumes commissioned by the Royal Society of London under a bequest from the last Earl of Bridgewater. The volume demonstrating (as Bridgewater’s bequest directed “the power, wisdom, and goodness of God, as manifested in the creation”) via physics was the work of the same William Whewell who invented the term “physicist.” Many individual physicists since have tried to unite traditional belief with their science, for example, Pascual Jordan, who found room for the freedom of the will in Bohr’s interpretation of quantum mechanics.

Bohr applied complementarity in the Greek direction, obtaining insight into the human condition from his understanding of physics. According to him, just as the physicist cannot give a complete description of his experiments without invoking formally contradictory concepts, like wave and particle, so the philosopher must rely on opposing concepts, like free will and determinism, for an exhaustive description of the world. And just as no realizable experimental arrangement can require a quantum entity to behave simultaneously as a wave and a particle, we cannot experience freedom and determinism together. Freedom applies in prospect, determinism in retrospect, religion not at all. Bohr once intended to write a book against religion to fulfill the moral obligation that his understanding of physics placed on him. Similarly, Einstein’s constant challenge to Bohr’s “tranquilizing philosophy or religion” responded to a moral imperative. It was not a reactionary objection to novelty, but a duty to science, to try to maintain the ideal of space-time description. His God who does not play dice represented this ideal: Einstein rejected the concept of a personal deity and an afterlife as firmly as Bohr did.

The modern evolution of the physicists’ world picture continues the ancient program of locating human beings in a directionless universe. We learn that the explosion that created it had to be nicely balanced to produce a state suitable for life. If too forceful, the primitive ingredients would have been scattered too far to form stars and galaxies; if too weak, the universe would have lasted only a second or two before sinking back into nothing. Apparently the initial power exercised, and the strengths of the forces subsequently at work, supplied the time needed (some 15 billion years) to develop intelligent life, which now uses its own existence as a criterion in designing accounts of the cosmos. This “anthropic hypothesis,” so named by Brandon Carter (Cambridge) in 1970, tickled the fancies of strong speculative minds, gave comfort to believers who saw the hand of God in the fine-tuning of the initial conditions, and appealed to atheists who interpreted our universe as a statistically improbable case of all possible universes originating in big bangs.

Another inference, implying a Bungling Demiurge rather than an Intelligent Creator, comes from the collection of investigations known as SETI (search for extraterrestrial intelligence). The US Congress voted a substantial sum to look for evidence of civilizations capable of producing electromagnetic messages. Not a peep has been heard despite the plausible assumption that among the billions and billions of possible habitats, some must have grown other beings during the last 15 billion years capable of inventing television. Is the universe not isotropic? Why then the silence? Perhaps the advanced civilizations we might imagine have had the foresight and skill to cordon off our corner of the universe. Or, perhaps more likely, electromagnetic civilizations do not survive long enough to give us a chance to tune into ET TV.

The universe as interpreted by modern physical science is horrifying as well as inspiring whether we are alone in it or not. The Earth, with its crashing plates, earthquakes, eruptions, hurricanes, and tsunamis is constantly exposed to bombardment from large meteors capable of wiping out most advanced life forms, as happened here only 66 million years ago. If a meteor or comet does not get us, we are sure to be destroyed by our own Sun. The heavens, which Aristotle pictured as a domain of eternal serenity, turn out to be filled with suicidal stars, black holes, super-energetic quasars, forbidding temperatures, and deadly radiations. Physicists believe that the universe originated in a catastrophic explosion of unimaginable violence owing to a chance fluctuation of nothing at all that scattered stars in their billions, and dark matter in its veil, through an indefinitely expanding or pulsating space. What, to repeat the quintessential question, is the place of humankind in this awesome world?

Steven Weinberg, who won a Nobel Prize for his part in advancing a TOE, gives the obvious adult answer: “The more we know about the universe, the more it is evident that it is pointless and meaningless.” That is no reason not to try to comprehend it, however. Weinberg again: “The effort to understand the universe is one of the very few things that lifts human life above the level of farce, and gives it some of the grace of tragedy.” In this telling, the purpose of the gigantic, finely tuned experiment is to give life the time and environment to evolve into physicists capable of developing theories of everything and inventing electromagnetic civilizations incapable of survival.

While awaiting the end, physicists pursuing modern versions of Greek speculations have exciting problems to solve. David Gross (Santa Barbara) has made a list of them. Here is the first: “can we actually say what happened at the beginning of the universe?” Hardly. We cannot even say what is happening now, since we are largely ignorant of the nature of the dark matter supposed to make up most of the mass of the universe. Perhaps CERN’s upgraded Large Hadron Collider, coming back into play in 2015, will make gluinos and neutralinos, the superparticles that supersymmetry offers as candidate constituents of the dark filling of the heavens. Physicists who remember Aristotle call this filling “quintessence.” Although gravity still eludes efforts to unite it with the three other fundamental forces, the case may be no worse than dark matter. And the worldwide collaboration Advanced LIGO (Laser Interferometer Gravitational-Wave Observatory), also to go on line in 2015, may detect the gravity waves that general relativity predicts as a product of collisions between black holes.

Why (Gross continues) do the fundamental parameters of the physicists’ world picture have the values we find? No Pythagoras has arisen to explain why the top quark (whose existence was established at Fermilab after the inspection of 500 trillion collisions) weighs 100,000 times as much as the up quark, or the proton almost 2,000 times as much as the electron, or why nature has been so generous as to provide physicists with three families each of quarks and leptons (electrons, light mesons, neutrinos). Why is the proton stable? Why does the universe contain so little antimatter? Are the universal constants really constant? Is the concept of space-time fundamental? Does the latest fad—string theory—have the answers? Perhaps. But, alas, Gross writes, “we really do not understand what string theory is.”

Is there time to learn?

Dedeifying and deanthropomorphizing nature produced physics, and physics now claims control of large swathes of territory previously ruled by capricious deities and organized religion. If the consequent picture of nature alarms humankind, that might reflect the healthy recognition that the world was not designed for us. The discoveries that no power made the universe for our pleasure, exploitation, or fright, and that there is no divine plot to history, can be liberating for people with the courage to accept them. Physics has given civilization a somber, disturbing, and challenging world picture, many fertile and some terrifying inventions, and notice of responsibility for the outcome of the human story. If humankind accepts the responsibility and the concomitant loss of providential deities and sacred dicta, the human species might beat the odds against the survival of an electromagnetic civilization, preserve the Earth, and, in the fullness of time, arrive at several satisfactory theories of everything.