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ORIGIN OF THE ORIGIN:
THE BIG BANG, SPECULATION, AND THE END OF SCIENCE
Frank Munley
The well-known big bang theory of our universe tells us that all we can physically
observe came into being in some unknown way about 13.5 billion years ago. One of the
most important pieces of observational evidence undergirding the theory is the existence
of the cosmic background radiation, originally very hot but now reduced to the form of
harmless, soft, cool microwaves just 3 degrees above absolute zero. The cosmic
microwave background (CMB) fills all space and partially penetrates Earth's atmosphere
to be absorbed by you and me. I would like to focus on the discovery of the CMB as an
example of how ideas originally borne of theoretical speculation succeed in becoming
serious science. Then I will look at the evolution of the big bang theory over the past 40
years, and share with you what I believe are serious problems in how modern science is
being practiced.
Genesis of the CMB and its discovery
The story begins in 1946, when the great physicist George Gamow (Figure 1)
attempted to explain the origin, and relative amounts, of different elements and concluded
that an expanding universe would have to be part of the picture. In 1948, Gamow's
associate Ralph Alpher predicted that the early universe should have been filled with hot
radiation that would limit the production of elements heavier than hydrogen (H) and
helium (He). Expansion of the universe would cool the radiation, and shortly after,
Alpher and Robert Herman predicted that space should be filled today with the CMB
radiation at a temperature of about 5 degrees above absolute zero. Predictions are one of
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the fruits of good theoretical physics, but until the CMB was experimentally observed,
the big bang theory remained in limbo.
Figure 1: George Gamow in 1956. Source: Center for History
of Physics, American Institute of Physics,
Physicshttp://www.aip.org/history/cosmology/ideas/gamow.htm
A fascinating part of the story is the 19-year delay in searching for the
background radiation. Stephen Weinberg, in his famous book on the big bang, The First
Three Minutes, gives three reasons for the delay. First, the primary goal of Gamow et
al.'s big bang theory, explaining the origin of the elements, was better-explained in 1957
by the more convincing theory that elements heavier than helium could be synthesized in
stars, which is what we believe today. Second, there was a failure of communication:
theorists were not aware of what experimentalists were capable of measuring, and
experimentalists were unaware of the prediction of the background radiation. And third,
the very idea that we could know anything of significance and substance about something
so remote in time pervaded the scientific community—a real failure of imagination!
The eventual discovery of the cosmic background radiation was the academic
equivalent of a masterful Tinker-to-Evers-to-Chance triple play. In 1965, a young
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theorist from Princeton, James Peebles, came to Johns Hopkins University and gave a
talk on the background radiation. (I was a JHU graduate student at the time and vaguely
remember Peebles' talk.) Peebles was associated with the great physicist Robert Dicke
who was searching for the background radiation even though he had no recollection of
Gamow et al's prediction. Dicke believed the most likely kind of universe would be an
infinitely old and oscillating one—a never-ending (and never-beginning) cycle of an
explosive big bang followed by a destructive big crunch followed by an explosive big
bang, etc., etc., reminiscent of Hindu religious cosmology. Dicke knew that background
radiation would be associated with such an oscillating universe and mounted an
experimental effort to detect it. But weeks before Dicke could do his experiment, which
surely would have succeeded, two scientists from Bell Labs, Robert Wilson and Arno
Penzias, were investigating radiation noise from outer space that might interfere with
microwave communication equipment manufactured by "Ma Bell." They discovered an
annoying microwave noise, but had no idea about its true origin or significance. As
Weinberg tells it, Penzias contacted Bernard Burke, a radio astronomer at MIT, about an
unrelated matter. Burke just happened to have talked with another physicist, Ken Turner,
who attended Peebles' Johns Hopkins talk. Burke asked Penzias about their search for
extraterrestrial noise sources, and Penzias said they discovered something but had no idea
what the source could be. Burke suggested they contact the team at Princeton. Dicke
must have known immediately that they had been scooped, and informed the Bell Lab
boys what they had found. So there you have it: Peebles to Turner to Burke to Penzias to
Dicke and we have one of the biggest home runs in modern science! The Nobel Prize for
the discovery went to the clueless Penzias and Wilson and neglected the prescient work
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of Dicke, Peebles, and others. If Burke had not talked to Turner, the prize would
undoubtedly have gone to Dicke and his Princeton crew. In any case, the time was ripe
for the discovery.
Certain lessons can be drawn from the discovery of the cosmic background
radiation. First, discoveries can occur in a serendipitous manner over a period of time,
thus lending credence that even in science, the historical beginning of a period can be
fuzzy and hard grist for the historian of science's mill. Second, the most imaginative
people don't always get the prize. And third, constant communication between scholars
is vital.
Successes of the Big Bang and Steady State
Any plausible theory must explain the following: (1) the universe at large consists
primarily of hydrogen and helium in the mass ratio of about 3:1; (2) the Hubble law,
according to which distant galaxies race away from us with speeds proportional to their
distances; and (3) the spectral shape of the CMB, which according to the big bang should
have a special “black body” spectral shape. An illustration of (2), from Gamow's own
hand, is shown in Figure 2.
Figure 2: "The dots run away from one another when the
rubber balloon is expanding," Gamow’s own drawing of
a 2-dimensional analog of an expanding 3-dimensional
universe. Source: G. Gamow, One, Two, Three, Infinity
(Viking Press, New York, 1961), p. 330.
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Figure 3 shows the spectacular agreement between big bang prediction and
observation of the cosmic background's spectral shape. The data points are hidden in the
theoretical curve—it doesn’t get much better than this!
FIGURE 3: The measurement errors are so small they are hidden behind the
thin theoretical curve. SOURCE: © 2007 Edward L. Wright. Last modified
on 15 Aug 2007. http://www.astro.ucla.edu/~wright/CMB.html
The big bang theory has had a constant competitor in the steady state theory of
the universe, formulated by the late great physicist Fred Hoyle and his associates. This
theory, called the quasi-steady state theory in its latest form, envisions an infinitely old
and infinitely large expanding universe in which the constant creation of matter prevents
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the universe from becoming largely empty space. Surprisingly, both the big bang and the
more recent quasi-steady state theories provide explanations for the three observations.
I must admit to a philosophical predisposition for the quasi-steady state theory,
but like the great majority of physicists, I have given it up in favor of the big bang. What
is it about the big bang that wins the day? In a nutshell, it is that this theory, when
combined with results from particle physics, gives a more economical, indeed more
beautiful, explanation of empirical observations than the quasi-steady state and other
theories. What does beauty have to do with physics? Plenty!
Poetry and science
Some of you might remember the great poet Coleridge's definition of beauty as
unity in variety. An example I use in my conceptual physics class is one line from
Shakespeare's Romeo and Juliet, discussed by Jacob Bronowski in his beautiful little
book Science and Human Values. In the face of Romeo's impending suicide, he ponders
the death of his most beloved. Inspired by her beauty even in death, Romeo refers to:
Death that hath suckt the honey of thy breath.
What a beautiful phrase: the "sting of death" was a common saying at the time, but when
it comes to Juliet, Shakespeare conjures up the life-spreading activity of the bee that
pollinates flowers and in the process makes lovely, fragrant honey from here breath. All
these different ideas are packed into that one short phrase. And so it is in science: we
yearn for theories which are economical in structure because they tie together a large
number of seemingly disconnected phenomenal. An ad hoc theory, on the other hand, is
one which is constantly modified to explain new, unexpected empirical evidence. What's
wrong with that? Ad hoc theories are not beautiful but are like Rube Goldberg
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contraptions—comical and inefficient, as they add devices to explain new experimental
data. A good theory, on the other hand, explains many observations with a bare
minimum of assumptions.
Throughout the years, the quasi-steady state theory came to consist of a number of
ad hoc patches and band aids to make it work. Quite a contrast to the big bang theory,
which for years predicted new results confirmed by experimental verification, and in the
process showed that ideas previously thought to be unconnected are really unified—a
good example of scientific unity in variety, of scientific beauty.
Evolution of the original big bang—art in science
Over the years, the simple theory Weinberg described in such brilliant terms has
been subject to many modifications, particularly one known as inflation which is an
exceptionally rapid expansion in the first 10-32 of a second of the universe's existence. So
we should now refer to the inflationary big bang theory of the universe's origin. The
inflationary big bang has been spectacularly successful in explaining a number of
puzzling facts, like why the universe’s geometry is flat and why it is so uniform.
Ironically, the inflationary theory allows for the possibility of a universe infinite in time
and space, similar to the steady state theory, but we can observe only a small part of it.
One triumph of inflationary cosmology involves the CMB spectrum shown
earlier. In fact, the curve shown in Figure 3 threatens to be too perfect, because if there
weren't small irregularities from the theoretical curve, it would imply that the universe is
too smooth. Just look around: the universe is lumpy, from air, water, and solids to stars
and galaxies. Figure 4 shows a tremendous success of modern astrophysics: different
colors in the picture correspond to tiny temperature variations in the CMB corresponding
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to irregularities in the universe about 300,000 years after the big bang and from which
lumpiness in the form of galaxies, stars, and planets originated. Inflation theory does an
excellent job of explaining the statistical properties of the irregularities. The lower part
of the figure is the same thing at a different scale and has recently been seen to indicate a
so-called "axis of evil" problem with the inflationary big bang. The significance of this
problem, and how serious a threat it is to the inflationary big bang, remains to be seen.
FIGURE 4: Temperature variations in the CMB tell us about variations in the density of matter
300,000 years after the big bang. SOURCE: Top: "MAP Glimpses Universe's Rambunctious
Childhood," Science, 299, 991-993 (14 FEBRUARY 2003). Bottom: "A singular conundrum: How
odd is our universe?", Science, 317, 1848-1850 (28 September 2007).
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To my taste, Figure 4 is a beautiful piece of pointillist-abstract art. Figure 5
shows Max Ernst's Dadaist Le monde des naifs, parts of which are vaguely similar to
Figure 4 and other parts of which conjure up thoughts of beautiful mathematics, physics,
astronomy, and colorful observations. And Figure 6 is a spectacular example of nature’s
own art: the famous “Pillars of Creation,” a spectacular picture of a stellar nursery.
FIGURE 5: Max Ernst, Le monde des naifs. (Photo of cover of The Undivided
Universe: An ontological interpretation of quantum theory, by D. Bohm and B.J.
Hiley, Routledge, London, 1993.)
FIGURE 6: “The Pillars
of Creation,” Hubble
Space Telescope in
the Eagle nebula (M16).
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Big bang problems and speculations
Modifications of the inflationary big bang continue to the present day. More
precise observations of the cosmic background radiation, galaxy and supernova counts,
cosmic distances, and galactic recession speeds have confirmed many predictions of the
theory, but have also given rise to problems that have led to wild theoretical speculations,
such as the existence of exotic forms of "dark" matter and energy and particles with
whimsical names like "wimps" and "machos." All of these exotics should be right here in
Earth’s environment, but have never been observed.
The inflationary big bang, to my mind, now threatens to become an ad hoc theory
lacking the important criterion of unity in variety, of beauty. An article in the 7 March
2003 issue of Science shows that the uncertainties in crucial parameters of the theory
allow the possibility that our universe might be oscillatory, just like Dicke thought back
in 1965, and not expanding as the standard big bang implies; or might be accelerating
outward due to dark energy, threatening to rip the entire cosmos apart. We just don't
know. A more sober view at this period of science history would, in my opinion, focus
on these uncertainties and give more serious consideration to ideas such as
"Modifications of Newtonian Dynamics" (MONDS) which might explain rotation rates
of stars around galaxies without the need for the hitherto unobserved, exotic, and
hypothetical dark matter and energy.
Why worry? Isn't this normal science?
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Speculation is vital to any science, but it is a double-edged sword. It can be used
to challenge existing theories, but it can also lead to theoretical constructs too clever by
half that buttress established "doctrine" in an ad hoc manner.
Nowhere have the speculations run more rampant than in the apparent
coincidences implied by the big bang. Take, for example, the existence of life, and in the
case of higher animals, of conscious life. Looking back in time, it appears that the big
bang process must have been extremely fine-tuned to give us the life-friendly properties
of atoms, particularly carbon atoms. These cosmic coincidences have led to all sorts of
speculations about the theological and philosophical implications of the big bang's
cosmological coincidences. I believe on the contrary that coincidences are a sign of
incomplete or incorrect understanding and will disappear when a true view of the
situation is obtained.
Why worry over the difficulties of the inflationary big bang? This would appear
to be normal science: two steps forward, one step back, as challenges brought by new
observations are met. But I do worry, because distance measurements, upon which the
entire subject of cosmology rests, suffer from serious problems that don't appear to be
taken sufficiently seriously. I worry that the big bang's theoretical and observational
structure is built on sand—not quicksand, but nonetheless sand of uncertain support. I
worry that the big bang has become a procrustean bed to which new theories are twisted
and pulled to fit. I have always firmly believed that one of the most important sources of
scientific progress is the appropriate admission that "we don't know." Should we start
looking in an entirely different direction? Should we take alternative ideas more
seriously, such as the MOND explanation of galactic rotation curves?
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I particularly worry that the normal process of science is being affected by the
kind of hype and exaggerated claims that pervade our political, economic, and cultural
life. The mainstream media love a story that has violence, and the big bang has always
fit the bill, all the more so now, since it is possible that the universe could be ripped to
shreds by a strange dark energy.
Ironic science and the end of real science
At this point, the inflationary big bang theory reigns, but in my opinion it is only a
useful theory, not a superb theory like quantum physics and relativity. It seems more and
more ad hoc and I occasionally find myself drawn back to the quasi-steady state theory,
as I try to carry out the balancing act between two vital scientific attitudes: skepticism of
new ideas and open-mindedness to them. But I am confident that sooner or later the
normal practices of science will triumph and decide the issue for the inflationary big bang
(most likely), the quasi steady state, or something altogether different.
A fundamental tenet of science is that theoretical ideas should have consequences
that are testable. Dark matter and energy should be right under our noses but so far
appear to be unobservable. These speculations and other aspects of the inflationary big
bang are reminiscent of what John Horgan, in his book The End of Science, calls ironic
science, i.e., science so far out that it is not testable. Ironic science is the end of real
science. Verifiable theories that explain a variety of phenomena in a unified way—
intellectual beauty in Coleridge’s sense—are the proper end of real science.