In A Beginning: Quantum Cosmology and Kabbalah - Part I
by Joel R. Primack and Nancy Ellen Abrams
Circinus Galaxy - Image courtesy of Nasa
Modern cosmology--the scientific study of the universe as a whole--no longer sees the universe as an infinite, changeless arena in which events take place, the way Isaac Newton did. The universe is an evolving, expanding being, and its origin is the oldest mystery. For the first time in possibly a million years of human wondering, we are not simply imagining the beginning. We are observing it, in radiation that has been traveling to us since the Big Bang, possibly bearing information generated even earlier. Theorists are piecing the data together into humanity’s first verifiable creation story.
Most educated people today have an essentially Newtonian picture of the universe as a place, devoid of all human meaning, in which we happen to find ourselves. If people come to understand the emerging scientific cosmology, however, they may see from what we know of the early universe that we actually are part of an extraordinary adventure. With its mind-expanding imagery, this emerging cosmology gives us a new cosmic perspective, a powerful source of awe, and a potential source of meaning in our everyday lives.
We will present the cosmological theory first directly, and then as if it were a creation myth, which it is. But here we encounter the limitations of the English language for the task: the universe is like nothing else. It’s not a thing that exists at any point in time but includes within it all time and all concepts. We will therefore turn to Kabbalah, medieval Jewish mysticism, as a possible source of language and metaphor, because certain kabbalistic concepts fit our picture amazingly well. Moreover, Kabbalah’s cosmology gave meaning and purpose to the everyday lives of its adherents, which we hope may become possible with the scientific cosmology emerging today.
The Large-Scale Structure of the Universe
While Newton believed that stars are randomly distributed through space, we now know that stars are organized into galaxies, and distant galaxies are flying away from each other as space expands. About ten percent of galaxies are in dense clusters, with many clusters linked by sheets or fine filaments of galaxies. Our own Galaxy, the Milky Way, is located in a small group of galaxies on the outskirts of the large sheet of galaxies (the local supercluster) in which the Virgo Cluster is embedded. On the scale of hundreds of millions of light years, there are millions of these enormous superclusters of galaxies; between them are great voids containing hardly any visible matter. Furthermore, vast flows of galaxies have been observed as a perturbation to the overall expansion of the universe. This is what astronomers call the "large-scale structure" of the universe, and much of it has been discovered only in the past decade.
As the universe expands, our neighboring galaxies will remain our neighbors forever, but farther out the expansion of space is carrying galaxies away so fast that we see their light stretched and reddened. The greater distance of expanding space we look across to see any particular galaxy, the faster that galaxy will be moving away from us. At last there is a distance where galaxies are being carried away by expanding space at the speed of light. This is our cosmic horizon. It is a spherical wall, and we are inside. Countless galaxies no doubt exist beyond, but they are whisked away by expansion. Their light cannot reach us, so we cannot see them. Every galaxy has its own horizon, its own "visible universe."
But visible matter, on scales of individual galaxies and larger, does not move as it should if it is all that exists out there. Stars in galaxies, and galaxies themselves in groups and clusters, move too rapidly to be held together by the visible matter. Something invisible is exercising enormous gravitational effects on visible matter. After eliminating all other possibilities, astronomers have in the last fifteen years accepted the weird idea that over ninety percent of the mass of the universe is not stars, dust, gas or anything we know, but instead some invisible substance called "dark matter." Dark matter does not emit or absorb any kind of radiation. Most of it is probably not made of electrons, protons, neutrons, or any of the familiar elementary particles. It forms an invisible halo around every galaxy perhaps ten times the radius of the disk of visible stars, and around every cluster of galaxies.
What is the dark matter made of? How much of it is out there, and where? How does it behave? There have been several competing theories that managed for years to agree with all the reliable data, because the data were so rough and incomplete. But most theories are now being shot down by new astronomical data which is rapidly accumulating from telescopes all over the world and in space. This has drastically narrowed the range of possibilities. Accordingly, coauthor Joel Primack has modified the theory he pioneered and which set the agenda for much of cosmology for over a decade, called Cold Dark Matter1. He is currently developing a new version of the theory, called Cold Plus Hot Dark Matter. "Cold" dark matter is some kind of hypothetical particles which were moving slugglishly in the early universe. "Hot" dark matter, which was moving relativistically then, may be composed of two kinds of neutrinos--at least, that is what’s suggested by the latest data from the particle physics laboratories. Each component of dark matter has its own characteristics, and each no doubt plays a crucial role in the history of the universe.
The Blueprint Came First
In 1929, Edwin Hubble discovered the expansion of the universe by showing that the more distant a galaxy is from us, the faster it is moving away. Astrophysicists ran the movie backward and realized that the universe had to have started out extremely hot and dense. The earliest point was named--derisively by astronomer and novelist Fred Hoyle, whose Steady State theory it eventually replaced--the Big Bang. Standard Big Bang theory explains the creation of the light elements of matter in the first three minutes and seems to be right as far as it goes, but it does not explain what preceded that or what has followed.
Gravity alone could not have created the complex largescale structures and flows of galaxies that are observed to exist. Gravity magnifies differences--that is, if one region is ever so slightly denser than average, it will expand slightly more slowly and grow relatively denser than its surroundings, while regions with less than average density will become increasingly less dense. But if matter after the Big Bang was absolutely evenly distributed, gravity would have done nothing but slow down the overall expansion. Consequently, either some unknown force acting after the Big Bang formed the giant structures we observe today--which looks increasingly dubious--or else gravity must have had some differences in density to work with from the beginning. What could have caused these differences in density? Big Bang theory is silent about its own initial
The theory of Inflation, proposed in the early 1980s by Alan Guth and others, says that for an extremely small fraction of a second before the Big Bang--much less time than it would take light to cross the nucleus of an atom-- the universe expanded exponentially, inflating countless random quantum events in the process. The density differences in the universe reflect these quantum events, enormously inflated. This is the best theory cosmologists have for the origin of the needed density differences. Inflation is exponential growth--the longer it goes on, the faster it gets. An old story illustrates its blinding speed:
A Sultan’s life was saved by the Grand Vizier. Overwhelmed with gratitude, the Sultan asked him to choose his reward. "You may give me a chessboard," said the Grand Vizier, "with one grain of wheat on the first square, two grains on the next square, four on the next, and so on. That would be enough." "Such a modest gift for so great an act?" the Sultan exclaimed. "You shall have it today!" But when the Sultan tried to prepare the chessboard, he discovered that the amount of wheat needed grew faster and faster. By the sixty-fourth square, he would need about ten billion metric tons-- twenty years’ worth of the modern world’s production of wheat.
The quantum events of cosmic inflation created the needed small differences in density from place to place, leaving space slightly wrinkled (in three dimensions). The wrinkles are extraordinarily subtle, like a hill 600 feet high compared to the 21,000,000 foot radius of earth, yet gradually they attracted particles of matter by gravity alone. The large-scale structures in the universe today--the clusters and walls built of thousands of galaxies-- illuminate these ancient wrinkles like glitter tossed on invisible lines of glue.
If the theory of Inflation is right, then the blueprint for the large-scale structure of the universe existed before the Big Bang created matter.
Can Inflation be Right?
The central predictions of the theory of Inflation are:
1) that the universe has critical density (i.e., contains just enough matter to keep slowing down the expansion, but not enough to cause the universe to stop or fall together in a Big Crunch) and
2) that the wrinkles, regardless of their wavelength, all have the same amplitude when they cross the horizon. (This is called a "Zel’dovich spectrum," after the great Russian physicist and cosmologist Yacov Borisovich Zel’dovich).
Arno Penzias and Robert Wilson discovered in 1965 that heat radiation from the Big Bang itself, called cosmic background radiation, still fills the universe. This was the first light in the universe. The radiation just reaching us now has been traveling since the universe first became transparent only about 300,000 years after the Big Bang. This primal radiation would have to bear some trace of the inflationary wrinkles that were theorized to have filled the universe at that time. If it did not, then the theory of Inflation had to be wrong, and the large-scale structure of the universe could not have formed by gravity alone. Numerous observations from earth’s surface and from planes and balloons detected no irregularity in the cosmic background radiation. Except for the effects of earth’s motion, the radiation appeared to be a perfectly uniform 2.7 degrees above absolute zero in every direction, until 1992.
In 1992 NASA’s Cosmic Background Explorer satellite (COBE), orbiting outside earth’s atmosphere, detected tiny differences in temperature in the background radiation. If Inflation is right, these differences are a lightly traced but readable fossil record of the period before the Big Bang--from which the Big Bang emerged. This is spectacular evidence of the existence of primordial wrinkles in space. What COBE found was the equivalent of lost baby pictures of immense cosmic structures, showing that they were not created whole but grew from these infants; and revealing as well, if read backwards, very intriguing implications about the babies’ parentage.
The theory of Inflation thus appears to be supported by the COBE discoveries and subsequent measurements by many other instruments. If we assume, and there is increasing evidence we should, that the density of cold plus hot dark matter is critical and that there is a Zel’dovich spectrum of wrinkles, the resulting theory produces large-scale structure like that which we actually observe. Since alternative explanations are perhaps possible, this does not prove that Inflation plus our dark matter theory are actually right, although if the predictions led to structures unlike what we see, that would certainly prove at least one of these assumptions is wrong. There are also potential stumbling blocks, such as some preliminary results
from Hubble Space Telescope suggesting (based on assumptions that may or may not be valid) that the universe may not be as old as some of the stars in our galaxy. But on balance the theory of Inflation is so beautiful and solves so many problems which initially appeared to be unrelated, it is hard to suppress the thought that it might actually be true.
While Inflation provides an explanation for the irregularities in the Big Bang, what about the origins of inflation itself? It turns out to be more fruitful to ask instead, why did inflation end? Because if we extrapolate backwards to find the origin of inflation, the most likely possibility is that in most of the superuniverse, inflation never stopped. It is a state of existence that goes on forever. The theory of Eternal Inflation, largely worked out by Russian astrophysicist Andre Linde, now at Stanford University, says that inflation stopped only in the minute part of the universe we can see--within our cosmic horizon-- and some unknown distance beyond that. Everywhere else it continues forever.
What Does It All Mean?
The ideas that follow are a sort of theoretical theology, a spiritual analogue of theoretical physics. A theoretical physicist’s methodology involves choosing a set of hypotheses and working out the consequences to see what kind of world they describe and how close it is to what experiment has found. Hypotheses can be eliminated as wrong but cannot be proved right. Coauthor Joel Primack and other cosmologists test theories by creating theoretical universes in supercomputers and then comparing them with observations of the real universe to see whether the predictions of any set of hypotheses can survive confrontation with the increasingly detailed data. Several fundamental truths about the origins and composition of the universe seem to be emerging from this process, although they are still controversial and they will be constantly tested as new data become available from the latest ground- and space-based telescopes. This is a logical game, but amazingly, sometimes the universe actually embodies a theorist’s dreams. When this happens, it can have the force of a religious experience--at least for the theorist involved!
So let us suppose--in the style of theoretical physics-- that the theories of Inflation and Eternal Inflation are correct and then think through some of the possible consequences for religion and culture.
To experience the human meaning of the scientific story, we must translate it into myth, the traditional form for stories about the origin of the world. In common parlance, "myth" has come to connote the opposite of reality, or the simplistic fare of the hopelessly backward or quaint. But myths, as they function in human societies, actually are explanations of the highest order: the stories a culture communally uses in order to connect with and give meaning to its universe. Every traditional culture known to anthropology has had a cosmology--a story of how the world began and how human beings took their place within it. A functional cosmology grounds people’s everyday expectations of each other in the larger patterns of the universe. Such a shared cosmology may be essential to successful human community and even to individual sanity. The understanding doesn’t have to be scientifically accurate. None ever has been, until now. No description is ever totally accurate anyway, unless it is the universe itself. The map is not the terrain. What we humanly need is to know the truest story of our time.
As Plato taught, the answer to the question "What does it all mean?" can only be a myth. Unlike other myths, however, a scientific myth never stands still. As long as the universe of knowledge expands, the myth must absorb, be tossed out by, or else be enfolded in larger understandings. No myth is for all time, but myth-making is an ongoing human pursuit.
This article is reprinted from Tikkun magazine: www.tikkun.org
About the Author
Nancy Ellen Abrams is a lawyer, writer, and performance artist, and her husband Joel R. Primack is a professor of physics at the University of California, Santa Cruz. They have been teaching a course at UCSC on Cosmology and Culture for 6 years. Primack currently serves on the executive committee of the American Physical Society Division of Astrophysics and chairs the advisory committee to the AAAS Program of Dialogue on Science, Ethics, and Religion. For more of Abrams and Primack's exciting work, see www.viewfromthecenter.org.