Science in Christian Perspective
THE BLACK HOLE OF SPA CETIME
Laurence B. Chase
Middlebury College, CT
From: JASA 25 (December 1973): 151-154.
The author of this article is Laurence B. Chase, an ad ministrator at Middlebury college, former science writer in Princeton's Office of Public Information. This excerpt was prepared by Intellectual Digest from the original article which appeared in University: A Princeton Quarterly (Number 53, Summer 1972), copyright Princeton University 1972. Reprinted with permission.
When John Archibald Wheeler takes exception to Shakespeare, it is out of his conviction that our fate is indeed inextricably bound up with the stars. Winner of some of the nation's major awards for science, adviser on defense matters to presidents and generals., Wheeler is Joseph Henry Professor of Physics at Princeton. He is currently absorbed in the study of "black holes"a phrase he has coined to describe the burned-out stars that have undergone gravitational collapse. It is the implications of such gravitational collapse, on an awesomely grander scale, that Wheeler caks "the greatest crisis one knows how to point to in the physics of our time." This is the possibility that the entire universe is destined to undergo a similar collapse, to become itself the ultimate, final "black hole."
Wheeler recently described the phenomenon to Laurence Chase in the relaxed atmosphere of his Princeton study.
Before we begin to grapple with questions about the entire universe, John Wheeler says, we must first understand something of the behavior of stars.
Gravitation, he points out, has to do with the birth of stars because it is through gravitational attraction that hydrogen atoms come together in space, eventually to such densities and pressures that great heat is generated, thermonuclear burning begins, and a star "turns on." Hydrogen is converted into helium, helium into carbon, carbon into heavier elements by a roundabout process. All the atoms in your body have come through such stellar furnaces now long banked; the mysterious process called life has merely rearranged the atoms into molecules, cells, fibers, proteins and so on.
Gravitation also has to do with the death of stars because its relentless contractive force continues after the thermonuclear fires have died. "White dwarf," "neutron star," "pulsar"-all are scientists' names for dead or dying stars. "Black hole" refers to the ultimate annihilation: gravitational collapse to oblivion.
The Black Hole
What, at first sight, could be more dramatic, more violent, than a black hole? Wheeler asks. In that devastating crunch of gravitational collapse, everything familiar is utterly destroyed. He has written of the process:
The collapse takes place on a characteristic time scale. For an object with a mass comparable to the mass of the sun this time is less than a millisecond. Let the original object have a hill on it. Then the effective height of this hill decreases to half its value in a characteristic relaxation time also less than a millisecond. Dropping to half value, then to quarter value, then to eighth value, and so on, with each stage lasting less than a millisecond, every geographical feature of the system by the end of a second is erased away to the utmost perfection.
Drop in a meteorite. It makes a momentary disturbance in the geometry . . . . Drop in familiar objects of the greatest variety of sizes and shapes. All details quickly disappear. We end up with an object characterized, so far as we can tell, by mass, charge, and angular momentum, and by nothing more. If we call the resulting entity a "black hole," then we can summarize the perfection of its final state by saying, "A black hole has no peculiarities."
Violence is not the only distinguishing characteristic of a black
hole. As Wheeler
describes it, and as science writers love to point out, few things seem weirder
than a black hole. Under the influence of its gravitational stronghold, strange
things happen to time and space and light. Time is said to take on spacelike
characteristics, space some features of time. To the earthling
uneducated in relativity
theory, nothing seems more natural, for relativity theory is, among
a precise expression of the interchangeable relationships between
matter and energy,
time and space.
At present, Wheeler hastens to point out, the strange and violent black hole exists unequivocally only in some scientists' minds. Two years ago he predicted that 1971 would be the "year of the black hole"-the year in which such an "object" would be found in space. He was mildly disappointed; the year ended without the clear, persuasive evidence that he predicted. Yet scientists did locate a source in the constellation Cygnus, which emits X rays thought to be characteristic of the area around a black hole-its "ergosphere," so named by Wheeler and his colleague, Remo J. Ruffini, because a particle that enters the region picks up energy (ergon5 in Greek) from the black hole.
Now the search is being intensified and may pay off in 1973, Wheeler says, as scientists learn how to interpret with more confidence those x-ray signals from space. But he warns, "Nothing could be a greater mistake than for physicists to step back satisfied, after the discovery of a black hole."
Collapse of the Universe
To Wheeler, the black hole is merely a distant early warning system for a phenomenon infinitely more violent and strange: gravitational collapse of the entire universe. It is that collapse, the ultimate collapse, that is never far from his fertile mind. The situation demands superlatives: "I count my work useful only insofar as it sheds light on this mystery, which is certainly the greatest crisis of the physics of our time."
Clearly, there are no greater extremes. This is Wheeler's view of the exact dimensions of the problem: a light year, the commonly used unit of astronomical distance, is just about 6,000,000,000,000 (six trillion) miles. The expanding sphere of space that we call our universe stretches in diameter more than 28 billion light years-about 170,000,000,000,000,000,000,000 miles-across. Ten billion years old, our universe is but a still-growing adolescent. Maturity-according to Wheeler's estimates, which are based on observations made at the Mt. Palomar Observatory in California will not be reached for another 20 billion years, when the universe's most distant points will he 23 x 1022 miles apart.
Then, for a flickering second, the impetus of expansion, imparted 30 billion years earlier by an inconceivably colossal "big bang," will be halted by the forces of gravitation that have been slowly braking the expansion since the beginning. Further expansion will be arrested, and gravitational collapse will begin.
The galaxies farthest from the earth-each a collection of millions of stars-will reverse direction, at first traveling slowly, then eventually approaching the speed of light itself. Fifty billion years from today (give or take a few billion years) our contracting universe will, figuratively, return to the womb.
But here is the crisis: like the black hole, Wheeler explains, the entire universe is predicted by Einstein's equations to arrive at a condition of infinite compaction in a finite time-a "preposterous prediction," because other equally important laws of physics encompassed under the general term "quantum principle" absolutely forbid the conclusions pointed to by Einstein's equations. Flow, then, to escape this paradox? Flow get back on the right track? How write a new scenario in which the universe escapes complete collapse, girds against the ultimate violence? At stake is the whole future of physics in our time. Put simply, buried here may he the "glittering central mechanism of the universe," the Rosetta Stone that Wheeler has been seeking for the past 20 years.
Wheeler is attempting to develop a safeguard-a fallout shelter built of theoretical physicsagainst the final, violent, universal collapse. And in that saving there is a kind of religious grace-sanctification-for man; for the vision he is developing turns out to suggest a universe peculiarly "tuned to man."
Actually, Wheeler got into the gravitation business in quite a proper scientific manner, not at all as prospective savior. Before and during the early war years, he and a Princeton graduate student, Richard P. Feynman, were trying to understand precisely how charged particles electrons and protons, for example interact with one another even over unlimited distances and across total vacuums. Feynman eventually solved that problem by pioneering a new field of physics known as quantum electro-dynamics. When Wheeler finished his weapons work he began to study precisely how uncharged, electrically neutral bodies-stars and planets, for example-interact with one another over distances. This was a problem similar to the one he and Feynman had studied, but complicated by the fact that no one had ever observed a gravitational wave. All this got very quickly and very deeply into Einstein's relativity theory, into gravitational collapse of stellar objects, into universal gravitational collapse, then into the paradox. the crisis: our universe is predicted to become packed into infinitely small dimensions in a finite time.
"But," says Wheeler, "these predictions cannot be right if the quantum principle is true, and we have no reason to doubt the quantum principle. With its indeterxninism, it gives us a new approach to the crisis of collapse. The problem now-the central problem-is to take the two overarching principles of twentiethcentury physics, the quantum principle and Einstein's general relativity, and incorporate them into one larger principle, with the ultimate aim of understanding the nature of space and time, matter and energy.
The Two Principles
Wheeler explains these "two overarching principles." "General relativity-or, to use a more descriptive word, geometro-dynamics--conceives of space itself as a dynamic entity, changing with time, influencing and being influenced by mass, in the same way that particles and electromagnetic waves are dynamic entities."
And every dynamic system that we've ever pursued in enough detail has been governed by the quantum principle, which says, in brief, that you can never predict deterministically-with complete precision-how a system will change in the future, because in order to predict deterministically how a system will change, you have to know two things: what it's doing right now and how fast it's changing. But the quantum principle says you cannot know both simultaneously; and we have no reason whatever to believe that there is any exception for space as a new dynamical feature of nature.
No principle that we know of in all of physics has the same universal power as the quantum principle. The more we pursue it, the more it looks as if it is the number one principle, and that everything else is, in some way we don't yet understand, derived from it.
In gravitational collapse of the universe, as in all other areas of physics, he
maintains, the principle of indeterminism evidences itself only at
But now we must journey to a world that makes subatomic particles
immense by comparison: an incredibly energetic world of
smaller than an electron by 20 powers of ten, each "thing" composed
of nothing hut-space itself, pure fluctuating space.
Citing the fact that gravitation and electromagnetism are both ways by which energy is propagated through space, Wheeler explains how he came upon the level of analysis at which "somethings" are created out of nothing:
To my mind no development in all of physics since World War II has been more impressive than that of quantum electrodynamics. It won Nobel prizes for Feynman, Sehwinger, Tomunuga and Lamb. Why, it gave us the idea that the electromagnetic field, which transmits electromagnetic radiation across empty space, is always fluctuating, never quiescent. This fluctuating force, which is additional to the force that an electron feels in its orbit around the nucleus of the atom, has in fact been measured; the electron feels a steady force from the nucleus, but it also feels a tiny fluctuating force that pervades all space. Why did these men suspect that the force was there? Because the quantum principle predicted that the electromagnetic field could net be quiescent, for that would violate indeterminism. Now the lesson to he drawn from that discovery, by inference, is that pure space, which transmits gravitational radiation, cannot be quiescent either; it moat be fluctuating. When examined at small-scale distances, it has to he 'jiggle-jaggliug' and irregular.
Wheeler suggests an analogy. "From an airplane six miles high, the ocean looks smooth. Down at sea level, in a life raft, however, we see that waves are breaking, and the surface is highly irregular; what's more, instead of its being merely irregular, there are droplets breaking loose. Now space, too, looks smooth at the scale of everyday life, smooth at the scale of atomic structure, and smooth at the scale of nuclear structure. But when one gets down to the scale of distances 20 powers of ten smaller than the scale of nuclear structure, then one predicts that space is fuamlike." The 10- centimeter dimension at which space becomes foamlike-the dimension at which something is created out of nothing-is known to Wheeler's Princeton colleagues as the Planck-Wheeler length, though Wheeler always calls it simply the Planck length.
Here, then, we return to the crisis: What happens to the dynamics of the universe, or of the black hole, when either is compressed to dimensions as small as the Planck-Wheeler length? For in this incredibly tiny world of random fluctuations, John Wheeler says, the future of the universe will be told.
Here the deterministic world of general relativity and its inevitable gravitational collapse, marching on its all-conquering path from the universe to the black hole, at last comes to a domain of distances where collapse loses its terror-where collapse is not only all the time taking place, but is also all the time being undone (fluctuations in space itself, all the time and everywhere). And if collapse at that quantum level of smallness is undone, dues this net say that the collapse of the universe itself, when it comes down to this level of distances, is also undone?
Convinced himself that black holes must exist arid lend themselves to
and working closely with colleagues to discover the many ways a black hole can
interact with its surroundings and show itself ("the sight and sound of a
black hole"), Wheeler regards the eventual discovery of these objects most
of all as an additional prod to get on with a deeper understanding of the world
of the very small. What happens to the black hole when it quickly reaches the
tiny world of random fluctuations? Where does everything go? Is there a certain
probability that the whole thing will expand again? That the
particles that lost
their identity in collapse will be reborn? And where? "There is
in Einstein's standard of relativity that a star with completely
will eventually emerge from the black hole," he says. "Nor is there
any indication that the matter will emerge somewhere else in space. But may it
emerge somewhere in another universe?"
Wheeler describes the matter in a black hole as being squeezed through a knothole in space, forced down to the world where fluctuations are everything, there to reemerge according to rules of probability not yet understood. The void of space is the stage on which the drama will unfold, and scientists hope to watch it safely at a distance, from the outside.
But how could anyone conceivably observe the collapse of the entire universe? If the universe is everything, on one can stand outside and watch, we are accustomed to think, But if indeterminism governs everything in extreme collapse, there must logically be some entity, some larger stage, sufficiently all-encompassing to contain a variety of possible new universes. The physicist explains:
The stage on which the space of the universe moves is certainly not space itself. Nobody can be a stage for himself; he has to have a larger arena in which to move. The arena in which space does its changing is not even the spacetime of Einstein, for spaeetisne is the history of space changing with time. The arena most he a larger object; superspace. Superspaee is not endowed with three or four dimensions-it's endowed with an infinite number of dimensions. Any single point in superspaee represents an entire, three-dimensional world; nearby points represent slightly different three-dimensional worlds.
Wheeler discovered-one might almost say "invented"-superspace in the late 1950s; and the idea that there could be something somehow "out there," beyond the universe and not a part of it, was picked up eagerly by his colleagues. Indeed, the quantum principle demanded it. Wheeler quotes philosopher William James: "Actualities seem to float in a wider sea of possibilities out of which they were chosen; and somewhere, indeterminism says, such possibilities exist, and form a part of the truth!" That "somewhere," for the physicist, is superspace.
A Conk's tour of superspace
To my mind, the dramatic new feature about super space is this: the shape of our universe changes with time as the universe expands, reaches a maximum dimension and contracts-and this history appears as a track in superspace. When the universe finally collapses, it comes to a region of superspace that represents an extreme condition, and the classical general relativity of Einstein offers no way to go beyond that point. If you try to solve the problem on a computer, the computer stops. Smoke comes out. But according to the quantum principle, the dynamics should continue. We can well expect that when the universe collapses, there's a certain probability that it will start a new cycle: one that will last not 80 billion years necessarily, but a million years-or 50 billion years. Each of these new dynamic histories of the universe, one can believe, will have its own peculiar number of particles in it and its own unique properties for those particles. Another universe will leave its own track in supcrspace, one quite different from our own universe.
Akin to Theology?
Ultimately, in the simplicity and strangeness of Wheeler's world, there is something akin to theology, for his vision of the continuous ebb and flow of the universe, each cycle with its own peculiar selection of physical laws and constants, offers, as he puts it with some awe, "a completely different view of the nature of man."
Well, Einstein's general relativity gives us a picture of a universe which starts from indefinitely small dimensions, expands to some maximum size, and some day contracts again to indefinitely small dimensions. This picture gives the impression that the universe is something that is just here by accident. In contrast, the idea that the dynamics goes on in superspace, that the universe makes many cycles, and that in each cycle all the properties are changed-the number of particles, the mass of the particles, the size of the universe, the length of the cycle this suggests that most cycles of the universe will not permit the development of stars like the sun, of planets like the earth, of the atoms and molecules necessary for life as we know it.
This suggests that there exists a degree of harmony between us and our surroundings that we never realized before. In the past, we looked at our surroundings as if there could be no other, something with which we just had to get along. If this new view is correct, our surroundings are very special and tuned to us, like a plant to its flower: this cycle of the universe like the plant, and we like the flower that comes into a brief bloom and then fades away.
You know, there has been a lot of talk about coal, oil, nuclear power and the sun as sources of energy. But to my mind the most important source of energy is the human being and what he believes. I can't think of anything more important than people's views of how man fits into the scheme of the universe. That's why I think this work we're doing now at Princeton is extremely important.