Chapter
in The Improbability of God,
eds. Michael Martin and Ricki Monnier (Amherst NY: Prometheus Books, 2006). Based on a chapter in God:
The Failed Hypothesis. How Science Shows that God Does Not Exist by Victor J. Stenger, to be published by Prometheus
Books in 2007.
Presented
here is an argument based on modern physics and cosmology against the existence
of a God who created the universe. It can be summarized as follows:
1. Hypothesize a God who is the highly intelligent and powerful supernatural creator of the physical universe.
2.
We can reasonably expect that
empirical evidence should exist for a purposeful and supernatural creation of
this cosmos, such as the observed violation of one or more laws of physics.
3. No
empirical evidence for a purposeful creation of the cosmos can be found. No
universal laws of physics were violated at the origin of the universe in which
we reside.
4.
Modern cosmology indicates that
the initial state of our universe was one of maximum chaos so that it contains
no memory of a creator.
5. Scientists
can provide plausible, purely natural scenarios based in well-established
cosmological theories that show how our universe may have arisen out of an
initial state of nothingness.
6.
We can conclude beyond a
reasonable doubt that a God who is the highly intelligent and powerful
supernatural creator of the physical universe does not exist.
From a modern scientific perspective, what are the
empirical and theoretical implications of a supernatural creation? We need to
seek evidence that the universe (1) had an origin and (2) that origin cannot
have happened naturally. One sign of a supernatural creation would be a direct
empirical confirmation that a miracle was necessary in order to bring the
universe into existence. That is, cosmological data should either show evidence
for one or more violations of well-established laws of nature or the theories
that successfully describe those data should require some causal ingredient
that cannot be understood in purely material or natural terms.
Now, as philosopher David Hume pointed out centuries
ago, many problems exist with the whole notion of miracles. Three types of
possible miracles can be identified: (1) violations of established laws of
nature, (2) inexplicable events, and (3) highly unlikely coincidences.
If a violation of an established law of nature is
observed, then we might more reasonably surmise that the law was wrong rather
than conclude that an occurrence of divine intervention has taken place. If we
simply define a miracle as an inexplicable occurrence, then how can we be sure
that an explanation will not someday be found? If we view some highly unlikely
coincidence as a miracle, how can we know it still was not a random accident?
These pose serious questions for anyone arguing from miracles to the existence
of God.1
However, that is not the task I have undertaken.
Theologian Richard Swinburne, who has undertaken that
task, suggests that we define a miracle as a non-repeatable exception to a law
of nature.2 Of course, we can always redefine the law to include the
exception, but that would be somewhat arbitrary. Laws are meant to describe
repeatable events. So, we will seek evidence for violations of well-established
laws that do not repeat themselves in any lawful pattern.
No doubt God, if he exists, is capable of repeating
miracles if he so desires. However, repeatable events provide more information
that may lead to an eventual natural explanation, while an unexplained,
unrepeated event is likely to remain unexplained. Let us give the God
hypothesis every benefit of the doubt and keep open the possibility of a
miraculous origin for inexplicable events and unlikely coincidences, examining
any such occurrences on an individual basis. If even with the loosest
definition of a miracle none is observed to occur, then we will have obtained
strong support for the case against the existence of a God who directs
miraculous events.
Let us proceed to look for evidence of a miraculous
creation in our observations of the cosmos.
Creating
Matter
The universe currently contains a large amount of matter that is characterized by the physical quantity we define as mass. Prior to the twentieth century, it was believed that matter could neither be created nor destroyed, just changed from one type to another. So the very existence of matter seemed to be a miracle, a violation of the assumed law of conservation of mass that occurred just onceÑat the creation.
However, in his special theory of relativity published
in 1905, Albert Einstein showed that matter can be created out of energy and
can disappear into energy. His famous formula E = mc2 relates the mass m of a body to an equivalent rest energy, E, where c
is a universal constant, the speed of light in a vacuum. That is, for all
practical purposes, mass and rest energy are equivalent, with a body at rest
still containing energy.
When a body is moving, it carries an additional energy
of motion called kinetic energy.
In chemical and nuclear interactions, kinetic energy can be converted into rest
energy, which is equivalent to generating mass.3 Also, the reverse
happens; mass or rest energy can be converted into kinetic energy. In that way,
chemical and nuclear interactions can generate kinetic energy, which then can
be used to run engines or blow things up.
So, the existence of mass in the universe violates no
law of nature. It can come from energy. But, where does the energy come from?
One of the most important principles of physics is the law of conservation
of energy, also known as the first
law of thermodynamics, which requires
that energy come from somewhere. In principle, the creation hypothesis could be
confirmed by the direct observation or theoretical requirement that
conservation of energy was violated 13.7 billion years ago at the start of the
big bang.
However, neither observations nor theory indicate this
to have been the case. The first law allows energy to convert from one type to
another as long as the total for a closed system remains fixed. Remarkably, the
sum of the rest kinetic energies of the bodies in the early universe seems to have
been exactly cancelled by the negative potential energy that results from their
mutual gravitational interactions. Within small measurement errors and quantum
uncertainties, the mean energy density of the universe is exactly what it
should be for a universe that appeared from an initial state of zero energy.
Furthermore, a close balance between positive and
negative energy is predicted by the modern version of the big bang theory
called the inflationary big bang,
according to which the universe underwent a period of rapid, exponential
inflation during a tiny fraction of its first second. The inflationary theory
has recently undergone a number of stringent observational tests that would
have been sufficient to prove it false. So far, it has passed these tests with
flying colors.4
In short, the existence of matter in the universe did
not require the violation of energy conservation at the assumed creation. In
fact, the data strongly support the hypothesis that no such miracle occurred.
If we regard such a miracle as predicted by the creator hypothesis, then that
prediction is not confirmed.
Creating
Order
Another
prediction of the creator hypothesis also fails to be confirmed by the data. If
the universe were created, then it should have possessed some degree of order
at the creationÐÐthe design that was inserted at that point by the Grand
Designer. This expectation of order is usually expressed in terms of the second
law of thermodynamics, which states
that the total entropy or disorder of a closed system must remain constant or increase
with time. It would seem to follow that if the universe today is a closed
system, it could not always have been so. At some point in the past, order must
have been imparted from the outside.
Prior to 1929, this was a strong argument for a creation. However, in that year astronomer Edwin Hubble reported that the galaxies are moving away from one another at speeds approximately proportional to their distance, indicating that the universe is expanding. This formed the earliest evidence for the big bang. For example, an expanding universe can have started in total chaos and still form localized order consistent with the second law.
The simplest way to see this is with a (literally)
homey example. Suppose that whenever you clean your house, you empty the
collected rubbish by tossing it out the window into your yard. Eventually the
yard would be filled with rubbish. However, you can continue doing this with a
simple expedient. Just keep buying up the land around your house and you will
always have more room to toss the rubbish. You are able to maintain localized
orderÐÐin your houseÐÐat the expense of increased disorder in the rest of the
universe.
Similarly, parts of the universe can become more orderly as the rubbish, or entropy, produced during the ordering process (think of it as disorder being removed from the system being ordered) is tossed out into the larger, ever-expanding surrounding space. The total entropy of the universe increases as the universe expands, as required by the second law. However, the maximum possible entropy increases even faster leaving increasingly more room for order to form. The reason for this is that the maximum entropy of a sphere of a certain radius (we are thinking of the universe as a sphere) is that of a black hole of that radius. The expanding universe is not a black hole and so has less than maximum entropy. Thus, while becoming more disorderly on the whole as time goes by, our expanding universe is not maximally disordered. But, once it was.
Suppose we extrapolate the expansion back 13.7 billion
years to the earliest definable moment when the universe was confined to the
smallest possible region of space that can be operationally defined, a Planck
sphere that has a radius equal to the
Planck length, 1.6 x 10-35
meter. As expected from the second law, the universe at that time had lower
entropy than it has now. However, that entropy was also as high as it possibly
could have been for an object that small, because a sphere of Planck dimensions
is equivalent to a black hole.
This may require further elaboration. We seem to be
saying that the entropy of the universe was maximal when the universe began,
yet it has been increasing ever since. Indeed, thatÕs exactly what we are
saying. When the universe began, its entropy was the highest it could be for an
object of that size, because the universe was equivalent to a black hole from
which no information can be extracted. Currently, the entropy is higher, but
not maximal, that is, not as high as it could be for an object of the
universeÕs current size. The universe is no longer a black hole.
When, at the beginning of the big bang, the entropy
was maximal, the disorder was complete and no structure was present. So, the
universe began with no structure, but has structure today because its entropy
is no longer maximal.
In short, according to our best current cosmological
understanding, our universe began with no structure or organization, designed
or otherwise. It was a state of chaos.
We are thus forced to conclude that the order we now
observe could not have been the
result of any initial design built into the universe at the so-called creation.
The universe preserves no record of what went on before the big bang. The
creator, if he existed, left no imprint.
Beginning
and Cause
The
empirical fact of the big bang has led some theists to argue that this, in
itself, demonstrates the existence of a creator. In 1951, Pope Pius XII told
the Pontifical Academy, ÒCreation took place in time, therefore there is a
Creator, therefore God exists.Ó5 The astronomer/priest Georges-Henri
Lema”tre, who first proposed the idea of a big bang, wisely advised the Pope
not to make this statement Òinfallible.Ó
Christian apologist William Lane Craig has made a
number of sophisticated arguments that he claims show that the universe must
have had a beginning and that beginning implies a personal creator.6
One argument is based on general relativity, the modern theory of gravity that was published by
Einstein in 1916 and which has, since then, passed many stringent empirical
tests.7
In 1970, cosmologist Stephen Hawking and mathematician
Roger Penrose, using a theorem derived earlier by Penrose, proposed that a singularity exists at the beginning of the big bang.8
Extrapolating general relativity back to zero time, the universe gets smaller
and smaller while the density of the universe and the gravitational field
increases. As the size of the universe goes to zero, the density and
gravitational field, at least according to the mathematics of general
relativity, become infinite. At that point, Craig claims, time must stop and,
therefore, no prior time can exist.
However, Hawking has repudiated his own earlier proof.
In his bestseller A Brief History of Time he avers, ÒThere was in fact no singularity at the beginning of the
universe.Ó9 This revised conclusion, concurred to by Penrose,
follows from quantum mechanics, the theory of atomic processes that was
developed in the years following the introduction of EinsteinÕs theories of
relativity. Quantum mechanics, which also is now confirmed to great precision,
tells us that general relativity, at least as currently formulated, must break
down at times less than the Planck time, 6.4 x 10-44 second, and distances smaller than the Planck
length, mentioned earlier. It follows that general relativity cannot be used to
imply that a singularity occurred prior to the Planck time and CraigÕs use of
the singularity theorem for a beginning of time is invalid.
Craig and other theists also make another, related
argument that the universe had to have had a beginning at some point because if
it were infinitely old, it would have taken an infinite time to reach the
present. However, as philosopher Keith Parsons has pointed out, ÒTo say the
universe is infinitely old is to say that it had no beginningÑnot a beginning
that was infinitely long ago.Ó10
Infinity is an abstract mathematical concept that was
precisely formulated in the work of mathematician Georg Cantor in the late
nineteenth century. However, the symbol Ô°Õ is used in physics simply as a
shorthand for Òa very big number.Ó Physics is counting. In physics, time is simply
the count of ticks on a clock. You can count backward as well as forward.
Counting forward you can get a very big but never mathematically infinite
positive number and time Ònever ends.Ó Counting backward you can get a very big
but never mathematically infinite negative number and time Ònever begins.Ó Just
as we never reach positive infinity, we never reach negative infinity. Even if
the universe does not have a mathematically infinite number of events in the
future, it still need not have an end. Similarly, even if the universe does not
have a mathematically infinite number of events in the past, it still need not
have a beginning. We can always have one event follow another, and we can
always have one event precede another.
Craig claims that if it can be shown that the universe
had a beginning, this is sufficient to demonstrate the existence of a personal
creator. He casts this in terms of the kal‰m cosmological argument, which is drawn from Islamic theology.11
The argument is posed as a syllogism:
1. Whatever
begins to exist has a cause.
2. The
universe began to exist.
3. Therefore,
the universe has a cause.
The kal‰m argument has been severely challenged by
philosophers on logical grounds,12 which need not be repeated here
since we are focusing on the science. In his writings, Craig takes the first
premise to be self-evident, with no justification other than common, everyday
experience. ThatÕs the type of experience that tells us the world is flat.
In fact, physical events at the atomic and subatomic
level are observed to have no evident cause. For example, when an atom in an
excited energy level drops to a lower level and emits a photon, a particle of
light, we find no cause of that event. Similarly, no cause is evident in the
decay of a radioactive nucleus.
Craig has retorted that quantum events are still
Òcaused,Ó just caused in a non-predetermined mannerÑwhat he calls
Òprobabilistic causality.Ó In effect, Craig is thereby admitting that the
ÒcauseÓ in his first premise could be an accidental one, something
spontaneousÑsomething not predetermined. By allowing probabilistic cause, he
destroys his own case for a predetermined creation.
We have a highly successful theory of probabilistic
causesÑquantum mechanics. It does not predict when a given event will occur
and, indeed, assumes that individual events are not predetermined. The one
exception occurs in the interpretation of quantum mechanics given by David
Bohm. 13 This assumes the existence of yet undetected sub-quantum
forces. While this interpretation has some supporters, it is not generally
accepted because it requires superluminal connections that violate the
principles of special relativitiy.14 More important, no evidence for
sub-quantum forces has been found.
Instead of predicting individual events, quantum
mechanics is used to predict the statistical distribution of outcomes of
ensembles of similar events. This it can do with high precision. For example, a
quantum calculation will tell you how many nuclei in a large sample will have
decayed after a given time. Or you can predict the intensity of light from a
group of excited atoms, which is a measure of the total number of photons
emitted. But neither quantum mechanics nor any other existing theoryÑincluding
BohmÕsÑcan say anything about the behavior of an individual nucleus or atom.
The photons emitted in atomic transitions come into existence spontaneously, as
do the particles emitted in nuclear radiation. By so appearing, without
predetermination, they contradict the first premise.
In the case of radioactivity, the decays are observed to follow an exponential decay Òlaw.Ó However, this statistical law is exactly what you expect if the probability for decay in a given small time interval is the same for all time intervals of the same duration. In other words, the decay curve itself is evidence for each individual event occurring unpredictably and, by inference, without being predetermined.
Quantum mechanics and classical (Newtonian) mechanics
are not as separate and distance from one another as is generally thought.
Indeed, quantum mechanics changes smoothly into classical mechanics when the
parameters of the system, such as masses, distances, and speeds approach the
classical regime.15 When that happens, quantum probabilities
collapse to either zero or 100 percent, which then gives us certainty at that
level. However, we have many examples where the probabilities are not zero or
100 percent. The quantum probability calculations agree precisely with the
observations made on ensembles of similar events.
Note that, even if the kal‰m conclusion were sound and
that the universe had a cause, why could that cause itself not be natural? As
it is, the kal‰m argument fails both empirically and theoretically without ever
having to bring up the second premise about the universe having a beginning.
Nevertheless, another nail in the coffin of the kal‰m
argument is provided by the fact that the second premise also fails. As we saw
above, the claim that the universe began with the big bang has no basis in current
physical and cosmological knowledge. The observations confirming the big bang
do not rule out the possibility of a prior universe. Theoretical models have
been published suggesting mechanisms by which our current universe appeared
from a pre-existing one, for example, by a process called quantum tunneling or
so-called Òquantum fluctuations.Ó16 The equations of cosmology that
describe the early universe apply equally for the other side of the time axis,
so we have no reason to assume that the universe began with the big bang.
We have already seen that no miracle is evident in the
big bang. It follows that its appearance could have been natural. Indeed, this
is the more rational conclusion based on the absence of any violation of known
physical principles. Prominent physicists and cosmologists have published, in
reputable scientific journals, a number of proposals for how the universe could
have come about Òfrom nothingÓ naturally.17 These are speculative,
to be sure, but they are speculations based on established knowledge. None
violate any known laws of physics. These authors do not claim to ÒproveÓ that
this is how it all happened. The burden of proof is on those who wish to claim
these scenarios are impossible.
In short, empirical data and the theories that
successfully describe those data indicate that the universe did not come about
by a purposeful creation. Based on our best current scientific knowledge, we
conclude beyond a reasonable doubt that a God who is the highly intelligent and
powerful supernatural creator of the physical universe does not exist.
NOTES
1. For
a discussion of these problems, see Nicholas Everitt, The Non-existence of
God (London: Routledge, 2004),
chapter 6.
2. Richard
Swinburne, The Existence of God
(Oxford: Clarendon, 1979), p. 229.
3. It
is commonly thought that only nuclear reactions convert between rest and
kinetic energy. This also happens in chemical reactions. However, the changes
in the masses of the reactants in that case are too small to be generally
noticed.
4. See,
for example, Alan Guth, The Inflationary Universe (New York: Addison-Wesley, 1997).
5. Pius
XII, ÒThe Proofs for the Existence of God in the Light of Modern Natural
Science,Ó Address of Pope Pius XII to the Pontifical Academy of Sciences, November
22, 1951, reprinted as ÒModern Science and the Existence of God,Ó The
Catholic Mind 49 (1972): 182-92.
6. Theism,
Atheism, and Big Bang Cosmology,
edited by William Lane Craig and Quentin Smith (Oxford: Clarendon, 1993).
7. See,
for example, Clifford M. Will, Was Einstein Right? Putting General
Relativity to the Test (New York:
Basic, 1986).
8. Stephen
Hawking and Roger Penrose, ÒThe Singularities of Gravitational Collapse and
Cosmology,Ó Proceedings of the Royal Society of London, series A, 314 (1970): 529-48.
9. Stephen
Hawking, A Brief History of Time: From the Big Bang to Black Holes (New York: Bantam, 1988), p. 50.
10. Keith
Parsons in J. P. Moreland and Kai Nielson, Does God Exist? The Debate
between Theists & Atheists
(Amherst, NY: Prometheus, 1993), p. 187.
11. William
Lane Craig, The Kal‰m Cosmological Argument (London: Macmillan, 1979) and Reasonable Faith (Wheaton, IL: Crossways, 1994). See also William Lane
Craig, The Cosmological Argument from Plato to Leibniz (London: Macmillan, 1980) for a history of
cosmological arguments.
12. Quentin
Smith in Theism, Atheism, and Big Bang Cosmology; Everitt, The Non-existence of God, pp. 68-72.
13. David
Bohm and B. J. Hiley, The Undivided Universe: An Ontological Interpretation
of Quantum Mechanics (London:
Routledge, 1993).
14. Discussed
in detail in Victor J. Stenger, The Unconscious Quantum: Metaphysics in
Modern Physics and Cosmology
(Amherst, NY: Prometheus, 1995).
15. Quantum
mechanics becomes classical mechanics when PlanckÕs constant h is set equal to zero.
16. David
Atkatz and Heinz Paegels, ÒOrigin of the Universe as Quantum Tunneling Event,Ó
Physical Review D25 (1982):
2065-73; Alexander Vilenkin, ÒBirth of Inflationary Universes,Ó Physical
Review D27 (1983): 2848-55; David Atkatz,
ÒQuantum Cosmology for Pedestrians,Ó American Journal of Physics 62 (1994): 619-27.
17. Edward
P. Tryon, ÒIs the Universe a Vacuum Fluctuation?Ó Nature 246 (1973): 396-97; Vilenkin, ÒBirth of Inflationary
UniversesÓ; Andre Linde, ÒQuantum Creation of the Inflationary Universe,Ó Lettere
Al Nuovo Cimento 39 (1984): 401-5.