From Skeptic vol. 4, no. 2, 1996, pp. 36-40. The following article is copyright ©1996 by the Skeptics
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Cosmythology: Was the Universe Designed to Produce Us?
By Victor J. Stenger
Recent developments in modern cosmology have been seized upon
to provide scientific support for the notion of intelligent design
to the universe. The latest version of the argument from design
is constructed around the so-called anthropic coincidences (Carter,
1974, 1983; Barrow and Tipler, 1986; Davies, 1982; Gribbin and
Rees, 1989). Here the claim is made that the values of fundamental
constants of nature are incredibly fine-tuned for the production
of life-perhaps even human life. This fine tuning is said to be
far too unlikely to have been accidental and that the only reasonable
conclusion is intelligent design, with human life as the intent.
Holmes Rolston, for example, in The Christian Century called
it "Shaken Atheism" (1986), Sharon Begley in Newsweek
described it as "Science and the Sacred" (1994), while
Robert Wright asked in Time, "What does science tell
us about God?" (1992).
Tuned For Life
No doubt the universe would look quite different with the tiniest
variation of the basic constants of physics. A slight difference
in the strength of gravity, the charge of the electron, or the
mass of the neutron, and life as we know it would not exist. The
human race could not have evolved in a universe with different
constants. Those who promote the notion of intelligent design
think they have found confirmation in the way the universe seems
to be exquisitely balanced on the tip of a needle for the purpose,
they argue, of producing us.
As yet no theory, including the currently highly successful Standard
Model of elementary particles and forces, predicts the values
of the fundamental constants of the universe. None is able to
specify such basic facts about the universe as why the proton
has the mass it does, or why the hydrogen atom has the size it
does. In the Standard Model, the basic constants of the universe
must still be put in by hand. No known first principle prevents
any of these constants from taking on a random value from zero
to infinity.
Several physical constants have values that one would not expect
from naive arguments of symmetry or ideas about the unity of phenomena.
Recent developments in particle physics suggest that all the fundamental
forces of nature were unified as a single force in the extremely
high energy of the early moments of the big bang. Today the forces
are no longer identical and the huge differences between force
strengths that we now measure are difficult to explain. For example,
the ratio of strength of the electric and gravitational forces
in an atom is 1039. That is, gravity and the electromagnetic
force differ by 39 orders of magnitude. For later purposes, I
will call this large number N1.
In the 19th century, the electric and magnetic forces were found
to be different aspects of the same basic electromagnetic force.
This unification occurred despite the fact that the magnetic force
on a charged particle is normally much smaller than the electric
force.
In the 1980s, electromagnetism and the weak nuclear force were
found to be different aspects of the same basic electroweak force.
This also came about in the face of the large difference between
force strengths observed in the laboratory. In this and the previous
examples, the differences in the observed strengths of unified
forces are explained in a natural way. When and if gravity is
unified with the other forces, its comparative weakness may be
shown to be similarly natural. Or it may be accidental.
Starting with Hermann Weyl in 1919, many have speculated about
the large size of the dimensionless number N1 and its possible
connection with other large numbers in cosmology and microphysics.
For example, the ratio of a typical stellar lifetime to the time
for light to traverse the radius of a proton is another dimensionless
number, N2 =1039, which is the same order of magnitude
as N1. This was the first of what are now called the anthropic
coincidences.
Most physicists greeted the N1 = N2 "coincidence" with
the same Bronx cheer, "pbzzzpht," that they give to
new interpretations of quantum mechanics. It seems like nothing
more than numerology. Look around at enough numbers and you are
bound to find some that appear connected (Gardner, 1991).
In 1961, however, R. Dicke argued that N1 is necessarily large
in order that the lifetime of main sequence stars be sufficient
to generate heavy chemical elements such as carbon. Furthermore,
N1 must be of the same order of N2 in any universe with heavy
elements. If the gravitational attraction in stars were comparable
in strength to the electric repulsion between protons, stars would
collapse long before nuclear processes could build up the heavier
chemical elements from the original hydrogen and deuterium (heavy
hydrogen). The formation of chemical complexity is only possible
in a universe of great age.
Biological life needs time to evolve, a stable source of energy
over that time, and raw material from which to build complex structures.
That raw material includes carbon and other heavy elements to
provide the diversity needed for the building of proficient organic
systems. While hydrogen, helium, and lithium were readily synthesized
in the first few minutes following the big bang, heavier nuclei
could not appear until much later, after they were synthesized
inside stars and released into space upon the explosive demise
of these stars. The existence of elements heavier than lithium
in our universe depends on what also appears to be some highly
unlikely coincidences.
Billions of years were needed for stars to form, to burn all their
hydrogen fuel while manufacturing heavier elements, and finally
to explode as supernovae, spraying their atoms into space. Once
in space, these elements cooled and accumulated into planets.
Billions of additional years were needed for at least one star
to provide a stable output of energy so that one of its planets
could develop life.
In a debate on the existence of God held at the University of
Hawaii on April 13, 1994, Christian theologian William Lane Craig
was asked from the audience how he could believe that human beings
have a special place in a universe that is so enormous and so
old compared to humankind. His answer was essentially that the
universe had to be very big and very old to produce us! Paraphrasing
Craig's answer, all the billions and billions of stars and galaxies
that spread over billions of light years in billions of years
were put there so that the chemistry needed for life and human
beings had time to evolve (Craig, 1990, 1992). My response: Why
not cockroaches?
The element-synthesizing processes in stars depend sensitively
on the properties and abundance of deuterium and helium produced
in the early universe. Deuterium would not exist if the neutron-proton
mass difference were just slightly different from its actual value.
The relative abundance of hydrogen and helium also depends strongly
on this parameter.
The hydrogen-helium abundance also requires a delicate balance
of the relative strengths of the gravitational and the weak nuclear
interaction. A slightly stronger weak force and the universe would
be 100 percent hydrogen, since all the neutrons in the early universe
would then have decayed. A slightly weaker weak force and few
neutrons would decay before being bound up with protons in helium
nuclei where insufficient energy prevents their decay. All the
protons would also be bound up, leading to a universe that was
100 percent helium. Neither of these extremes would have allowed
for the existence of stars and life based on chemistry.
The electron also enters into the tightrope act needed to produce
the heavier elements. Because the electron mass is less than the
neutron-proton mass difference, a free neutron can decay into
a proton, electron and neutrino. If this were not the case, the
neutron would be stable and most of the protons and electrons
in the early universe would have combined to form neutrons, leaving
little hydrogen to act as the main component and fuel of stars.
It is also rather convenient that the neutron is heavier than
the proton, but not so much heavier that neutrons cannot be bound
in nuclei. The evolution of life on earth thus depends critically
on these relative force strengths and mass differences. With the
slightest change of these values, the variety and diversity of
the chemical elements would not exist. In their tome, The Anthropic
Cosmological Principle, John D. Barrow and Frank J. Tipler
have gone to great lengths in seeking many similar connections
-- some quite remarkable, others a bit strained -- between the
physical parameters of our universe and the formation of complex,
low energy material structures (1986).
Carbon appears to be the chemical element best suited to act as
the building block for the type of complex molecular systems that
develop lifelike qualities. Even today, new materials assembled
from carbon atoms exhibit remarkable, unexpected properties, from
superconductivity to ferromagnetism. However, it is carbon chauvinism
to assume that only carbon life is possible. We can imagine life
based on silicon or other elements chemically similar to carbon,
but these would still require cooking in stars. Hydrogen, helium,
and lithium, which were synthesized in the big bang, are all chemically
too simple to be assembled into diverse structures.
Furthermore, it seems like molecular chauvinism to rule out other
forms of matter in the universe as building blocks of complex
systems. While atomic nuclei, for example, do not exhibit the
diversity and complexity seen in the way atoms assemble into molecular
structures, perhaps they might be able to do so in a universe
with different properties. Sufficient complexity and long life
are probably the only ingredients needed for a universe to produce
life. Carbon may be unlikely, but as I will show, long life and
complexity are not.
Fingers and TOEs
The anthropic coincidences resonate with the mystical notions
that human existence is deeply connected to the very nature of
the universe. However, from the time of Copernicus, cosmology
has been based on the principle that the universe is indifferent
to humanity and human concerns. Most physicists are not quite
ready to give up on the Copernican principle. They believe it
should be possible to derive the values of the fundamental constants
of nature from a yet-undiscovered Theory-of-Everything (TOE) that
arises from a set of principles that operates at the level of
subnuclear particles, not biological cells.
It is very unlikely that a direct causal connection will ever
be found between fundamental processes that apply at subnuclear
scales and the details of complex structures on the macroscopic
scale of everyday life. I doubt if any TOE will tell us why we
have five toes on each foot, or why the three-toed sloth has three.
Most of the properties of the macroscopic world were not predetermined
by events in the early big bang, but emerged by the processes
of chance and natural selection.
As pointed out by Stephen Jay Gould (1989), rewinding the tape
of evolution and playing it back again would have infinitesimal
probability of once again producing Homo sapiens. I can conceive
the possibility that some or all of the constants of physics also
took on the values they did by chance and, like evolution, were
not designed by either a Creator or physical law.
The chance that any initially random set of constants would correspond
to the set of values they now hold in our universe is very small.
Cosmologist Roger Penrose (1989) has calculated that the probability
of our universe is one part in (1010)123.
In The Emperor's New Mind, Penrose has a cartoon of the Creator
pointing a finger toward an "absurdly tiny volume in the
phase space of possible universes" to produce the universe
in which we live. This has given comfort to believers. In the
Hawaii debate mentioned above, theologian Craig argued that this
unimaginable low probability illustrates the need for a Creator,
because the universe could not have happened by chance. Most of
the audience greeted that with enthusiastic nods. Only a few of
us sat there with puzzled looks on our faces.
But claiming our that universe is a miracle because of its unlikelihood,
calculated after the fact, is like the TV ads for publisher sweepstakes
that sing "Miracles can happen, can happen to you" if
you simply send in your entry. It may seem like a miracle to the
person who wins ten million dollars, but it was a certainty that
someone would win. It is like calling the sunrise each morning
a miracle.
Every human being on earth is the product of a highly elaborate
combination of genes that would be a very unlikely outcome of
a random toss. Think of what an unlikely being you are, the product
of so many chance encounters between your male and female ancestors.
What if your great-great-great grandmother had not survived that
childhood illness? What if your grandfather had been killed by
a stray bullet in the war, before he met your grandmother? Despite
all those other possibilities, you still exist. If you ask, after
the fact, what is the probability for your particular set of genes
existing, the answer is 100 percent! Certainty!
Similarly, the probability for the universe we live in existing
as it does, having the values of the fundamental constants that
it has, is not one in (1010)123. It is 100
percent! Some universe happened, and it happened to be the one
we have.
Still, it is argued that if a universe were created with random
values of the physical constants, a universe with no life would
have almost certainly been the result. Of course, no one would
then be around to talk about it and the fact is we are here and
talking about it.
Unfortunately, we have no way of talking about it with strict
rationality. We do not have enough information in the form of
examples of other universes to use as data to draw reasonable
conclusions.
One way to "explain" the anthropic coincidences within
the framework of existing knowledge of physics and cosmology is
to view our universe as just one of a very large number of mini-universes
in an infinite super-universe (Linde, 1994). Each mini-universe
has a different set of constants and physical laws. Some might
have life of different form than ours, others might have no life
at all or something even more complex that we cannot imagine.
Obviously we are in one of those universes with life. (Incidentally,
this multi-universe picture is often confused with Hugh Everett's
1957 "many-worlds interpretation" of quantum mechanics.
They are not at all related.)
Several commentators have argued that a many-universes cosmology
violates Occam's razor. I beg to differ. The entities that the
law of parsimony forbids us from multiplying beyond necessity
are theoretical hypotheses, not universes. Though the atomic theory
multiplied the number of bodies we consider in solving a thermodynamic
problem by 1024 or so per gram, it did not violate
Occam's razor. Rather it provided a simpler, more powerful exposition
of the rules that were obeyed by thermodynamic systems.
Similarly, if the many-universes cosmology provides an explanation
for the origin of our universe that does not require the highly
nonparsimonious introduction of a supernatural element that has
heretofore not been required to explain any observations, then
that explanation is more economical.
An infinity of random universes is suggested by the modern inflationary
model of the early universe. A quantum fluctuation can produce
a tiny, empty region of curved space that will expand exponentially,
increasing its energy sufficiently in the process to produce energy
equivalent to all the mass of the universe in a mere 10-42
second. Cosmologist Andre Linde has proposed that a spacetime
"foam" empty of matter and radiation will experience
local quantum fluctuations in curvature, forming bubbles of "false
vacuum" that individually inflate, as described above, into
mini-universes with random characteristics (Linde, 1982, 1987;
Atkatz, 1994). In this view, our universe is one of those expanding
bubbles, the product of a single monkey banging away at the keys
of a single word processor.
Toy Universes
I thought it might be fun (and instructive) to see what some of
these universes might look like. Of course, other universes may
have different physical laws and we have no idea what those laws
might be, although we can always speculate. All we really know
is our universe and its laws. Even in this case, different values
of the constants that go into our familiar equations will lead
to universes that do not look a bit like ours.
From the values of just four fundamental constants, the physical
properties of matter from the dimensions of atoms to the length
of the day and year to the age of main sequence stars can be estimated.
Two of these constants are the strengths of the electromagnetic
and strong nuclear interactions. The other two are the masses
of the electron and proton.
This is not, of course, the whole story. Many more constants are
needed to fill in the details of our universe. The gross properties
of our universe are determined by these four constants, and we
can vary them to see what a universe might grossly look like with
different values of these constants.
I have written a program -- MonkeyGod
-- posted on my web site, which the reader is welcome to use.
Try your own hand at generating universes. Just choose different
values of the four constants and see what happens. While these
are really only "toy" universes, the exercise illustrates
that there could be many ways to produce a universe old enough
to have some form of life.
The program computes the following quantities: the (Bohr) radius
and binding energy of the hydrogen atom, the radius of a nucleon
(proton or neutron) and its binding energy in a nucleus, the lifetime
and mass of a typical star, and the radius, length of day, and
length of year for a typical planet. It also computes the numbers
N1 and N2 mentioned earlier. (The astronomical quantities were
calculated using the formulas of Press and Lightman, 1983.)
The lifetime and mass of a typical main sequence star sets the
scale for the age of a universe populated, in the vicinity of
at least one such star, by complex material systems assembled
from chemical elements produced in the stars themselves. Thus
we can easily determine what a universe will look like if it possesses
values of the basic parameters that differ from our own.
Here are some typical outputs. The strength of the electromagnetic
force is given by alpha (for greater familiarity, 1/alpha is printed
out). The strength of the strong nuclear force is alpha_s. Both
of these quantities are dimensionless (that is, they have no units).
The electron mass is indicated by Me, the proton mass by Mp. Both
are in kilograms. In the tables right, I have rounded off most
of the results since only orders of magnitude are really significant
in a calculation of this type. The abbreviation for the units
in the answers are standard in any physics text.
Figure 1 shows a scatter plot of N2 vs. Nl for 100 universes in
which the values of the four parameters were generated randomly
from a range five orders of magnitude above to five orders of
magnitude below their values in our universe, that is, over a
total range of 10 orders of magnitude. We see that, over this
range of parameter variation, Nl is at least 1033 and
N2 at least 1020 in all cases. That is, both are still
very large numbers. Although many pairs do not lie exactly on
the diagonal N1 = N2, the coincidence between these two quantities
is not supernaturally rare.
The distribution of stellar lifetimes for these same 100 universes
is shown in Figure 2. While a few are low, most are clearly high
enough to allow time for stellar evolution and heavy element nucleosynthesis.
I think it is safe to conclude that the conditions for the appearance
of a universe with life are not supernaturally so improbable as
those authors enamored by the anthropic principle would have you
think.
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