The Awesome Universe
What the Big Bang Explains—What It Doesn’t
EVERY morning is a miracle. Deep inside the morning sun, hydrogen is being fused into helium at temperatures of millions of degrees. X rays and gamma rays of incredible violence are pouring out of the core into the surrounding layers of the sun. If the sun were transparent, these rays would blast their way to the surface in a few searing seconds. Instead, they begin to bounce from tightly packed atom to atom of solar “insulation,” gradually losing energy. Days, weeks, centuries, pass. Thousands of years later, that once deadly radiation finally emerges from the sun’s surface as a gentle shower of yellow light—no longer a menace but just right for bathing earth with its warmth.
Every night is a miracle too. Other suns twinkle at us across the vast expanse of our galaxy. They are a riot of colors, sizes, temperatures, and densities. Some are supergiants so large that if one were centered in the position of our sun, what remained of our planet would be inside the surface of that superstar. Other suns are tiny, white dwarfs—smaller than our earth, yet as heavy as our sun. Some will peacefully drone along for billions of years. Others are poised on the brink of supernova explosions that will obliterate them, briefly outshining entire galaxies.
Primitive peoples spoke of sea monsters and battling gods, of dragons and turtles and elephants, of lotus flowers and dreaming gods. Later, during the so-called Age of Reason, the gods were swept aside by the newfound “magic” of calculus and Newton’s laws. Now we live in an age bereft of the old poetry and legend. The children of today’s atomic age have chosen as their paradigm for creation, not the ancient sea monster, not Newton’s “machine,” but that overarching symbol of the 20th century—the bomb. Their “creator” is an explosion. They call their cosmic fireball the big bang.
What the Big Bang “Explains”
The most popular version of this generation’s view of creation states that some 15 to 20 billion years ago, the universe did not exist, nor did empty space. There was no time, no matter—nothing except an infinitely dense, infinitely small point called a singularity, which exploded into the present universe. That explosion included a brief period during the first tiny fraction of a second when the infant universe inflated, or expanded, much faster than the speed of light.
During the first few minutes of the big bang, nuclear fusion took place on a universal scale, giving rise to the currently measured concentrations of hydrogen and helium and at least part of the lithium in interstellar space. After perhaps 300,000 years, the universewide fireball dropped to a little below the temperature of the surface of the sun, allowing electrons to settle into orbits around atoms and releasing a flash of photons, or light. That primordial flash can be measured today, although greatly cooled off, as universal background radiation at microwave frequencies corresponding to a temperature of 2.7 Kelvin.a In fact, it was the discovery of this background radiation in 1964-65 that convinced most scientists that there was something to the big bang theory. The theory also claims to explain why the universe appears to be expanding in all directions, with distant galaxies apparently racing away from us and from each other at high speed.
Since the big bang theory appears to explain so much, why doubt it? Because there is also much that it does not explain. To illustrate: The ancient astronomer Ptolemy had a theory that the sun and planets went around the earth in large circles, making small circles, called epicycles, at the same time. The theory appeared to explain the motion of the planets. For centuries as astronomers gathered more data, the Ptolemaic cosmologists could always add extra epicycles onto their other epicycles and “explain” the new data. But that did not mean the theory was correct. Ultimately there was just too much data to account for, and other theories, such as Copernicus’ idea that the earth went around the sun, explained things better and more simply. Today it is hard to find a Ptolemaic astronomer!
Professor Fred Hoyle likened the efforts of the Ptolemaic cosmologists at patching up their failing theory in the face of new discoveries to the endeavors of big bang believers today to keep their theory afloat. He wrote in his book The Intelligent Universe: “The main efforts of investigators have been in papering over contradictions in the big bang theory, to build up an idea which has become ever more complex and cumbersome.” After referring to Ptolemy’s futile use of epicycles to rescue his theory, Hoyle continued: “I have little hesitation in saying that as a result a sickly pall now hangs over the big bang theory. As I have mentioned earlier, when a pattern of facts becomes set against a theory, experience shows that it rarely recovers.”—Page 186.
The New Scientist magazine of December 22/29, 1990, echoed similar thoughts: “The Ptolemaic method has been lavishly applied to . . . the big bang cosmological model.” It then asks: “How can we achieve real progress in particle physics and cosmology? . . . We must be more honest and forthright about the purely speculative nature of some of our most cherished assumptions.” New observations are now pouring in.
Questions the Big Bang Does Not Answer
A major challenge to the big bang has come from observers using the corrected optics of the Hubble Space Telescope to measure distances to other galaxies. The new data is giving the theorists fits!
Astronomer Wendy Freedman and others recently used the Hubble Space Telescope to measure the distance to a galaxy in the constellation of Virgo, and her measurement suggests that the universe is expanding faster, and therefore is younger, than previously thought. In fact, it “implies a cosmic age as little as eight billion years,” reported Scientific American magazine just last June. While eight billion years sounds like a very long time, it is only about half the currently estimated age of the universe. This creates a special problem, since, as the report goes on to note, “other data indicate that certain stars are at least 14 billion years old.” If Freedman’s numbers hold up, those elderly stars would turn out to be older than the big bang itself!
Still another problem for the big bang has come from steadily mounting evidence of “bubbles” in the universe that are 100 million light-years in size, with galaxies on the outside and voids inside. Margaret Geller, John Huchra, and others at the Harvard-Smithsonian Center for Astrophysics have found what they call a great wall of galaxies some 500 million light-years in length across the northern sky. Another group of astronomers, who became known as the Seven Samurai, have found evidence of a different cosmic conglomeration, which they call the Great Attractor, located near the southern constellations of Hydra and Centaurus. Astronomers Marc Postman and Tod Lauer believe something even bigger must lie beyond the constellation Orion, causing hundreds of galaxies, including ours, to stream in that direction like rafts on a sort of “river in space.”
All this structure is baffling. Cosmologists say the blast from the big bang was extremely smooth and uniform, according to the background radiation it allegedly left behind. How could such a smooth start have led to such massive and complex structures? “The latest crop of walls and attractors intensifies the mystery of how so much structure could have formed within the 15-billion-year age of the universe,” admits Scientific American—a problem that only gets worse as Freedman and others roll back the estimated age of the cosmos still more.
“We Are Missing Some Fundamental Element”
Geller’s three-dimensional maps of thousands of clumped, tangled, and bubbled galactic agglomerations have transformed the way scientists picture the universe. She does not pretend to understand what she sees. Gravity alone appears unable to account for her great wall. “I often feel we are missing some fundamental element in our attempts to understand this structure,” she admits.
Geller enlarged on her misgivings: “We clearly do not know how to make large structure in the context of the Big Bang.” Interpretations of cosmic structure on the basis of current mapping of the heavens are far from definitive—more like trying to picture the whole world from a survey of Rhode Island, U.S.A. Geller continued: “Someday we may find that we haven’t been putting the pieces together in the right way, and when we do, it will seem so obvious that we’ll wonder why we hadn’t thought of it much sooner.”
That leads to the biggest question of all: What is supposed to have caused the big bang itself? No less an authority than Andrei Linde, one of the originators of the very popular inflationary version of the big bang theory, frankly admits that the standard theory does not address this fundamental question. “The first, and main, problem is the very existence of the big bang,” he says. “One may wonder, What came before? If space-time did not exist then, how could everything appear from nothing? . . . Explaining this initial singularity—where and when it all began—still remains the most intractable problem of modern cosmology.”
An article in Discover magazine recently concluded that “no reasonable cosmologist would claim that the Big Bang is the ultimate theory.”
Let us now go outdoors and contemplate the beauty and the mystery of the starry vault.
a A kelvin is the unit of a temperature scale whose degree is the same as the degree on the Celsius temperature scale, except that the Kelvin scale begins at absolute zero, that is 0 K.—the equivalent of -273.16 degrees Celsius. Water freezes at 273.16 K. and boils at 373.16 K.
[Box on page 5]
The Light-Year—A Cosmic Yardstick
The universe is so big that measuring it in miles or kilometers is like measuring the distance from London to Tokyo with a micrometer. A more convenient unit of measurement is the light-year, the distance that light travels in a year, or about 5,880,000,000,000 miles [9,460,000,000,000 km]. Since light is the fastest thing in the universe and requires only 1.3 seconds to travel to the moon and about 8 minutes to the sun, a light-year would seem to be truly enormous!