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. 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.
[Footnote]
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.
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!
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