The Portable Atheist: Essential Readings for the Nonbeliever (52 page)

The only laws of matter are those which our minds must fabricate, and the only laws of mind are fabricated for it by matter.

—J
AMES
C
LERK
M
AXWELL

Miracles

Let us now move from Earth to the cosmos in our search for evidence of the creator God of Judaism, Christianity, and Islam. From a modern scientific perspective, what are the empirical and theoretical implications of the hypothesis 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 models developed to describe those data should require some causal ingredient that cannot be understood—and be probably not understandable—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. The latter two can be subsumed into the first since they also would imply a disagreement with current knowledge.

In previous chapters I have given examples of observations that would confirm the reality of supernatural powers of the human mind. We can easily imagine cosmic phenomena that would forever defy material expectations. Suppose a new planet were to suddenly appear in the solar system. Such an observation would violate energy conservation and reasonably be classified as a supernatural event.

Scientists will make every effort to find a natural mechanism for any unusual event, and the layperson is likely to agree that such a mechanism might be possible since “science does not know everything.”

However, science knows a lot more than most people realize. Despite the talk of “scientific revolutions” and “paradigm shifts,” the basic laws of physics are essentially the same today as they were at the time of Newton. Of course they have been expanded and revised, especially with the twentieth-century developments of relativity and quantum mechanics. But anyone familiar with modern physics will have to agree that certain fundamentals, in particular the great conservation principles of energy and momentum, have not changed in four hundred years.
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The conservation principles and Newton’s laws of motion still appear in relativity and quantum mechanics. Newton’s law of gravity is still used to calculate the orbits of spacecraft.

Conservation of energy and other basic laws hold true in the most distant observed galaxy and in the cosmic microwave background, implying that these laws have been valid for over thirteen billion years. Surely any observation of their violation during the puny human life span would be reasonably termed a miracle.

Theologian Richard Swinburne suggests that we define a miracle as a nonrepeatable exception to a law of nature.
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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 description, while a mysterious, unrepeated event is likely to remain mysterious. 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

Until early in the twentieth century, there were strong indications that one or more miracles were required to create the universe. 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 once—at 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. What all science writers call “Einstein’s famous equation,”
E = mc
²
,
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, a body at rest still contains 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.
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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. Mass can come from energy. But, then, where does the energy come from? The law of conservation of energy, also known as the
first law of thermodynamics,
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 indicates 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 total energy of the universe appears to be zero. As famed cosmologist Stephen Hawking said in his 1988 best seller,
A Brief History of Time,
“In the case of a universe that is approximately uniform in space, one can show that the negative gravitational energy exactly cancels the positive energy represented by the matter. So the total energy of the universe is zero.
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Specifically, within small measurement errors, 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, within a small quantum uncertainty.
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A close balance between positive and negative energy is predicted by the modern extension 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.
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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 successfully passed all these tests.

In short, the existence of matter and energy 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.

This example also serves to once more refute the assertion that science has nothing to say about God. Suppose our measurement of the mass density of the universe had
not
turned out to be exactly the value required for a universe to have begun from a state of zero energy. Then we would have had a legitimate, scientific reason to conclude that a miracle, namely, a violation of energy conservation, was needed to bring the universe into being. While this might not conclusively prove the existence of a creator to everyone’s satisfaction, it would certainly be a strong mark in his favor.

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 creation—the 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 miraculous 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 provided the earliest evidence for the big bang. For our purposes, an expanding universe could have started in total chaos and still formed 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 order—in your house—at 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. As illustrated in figure 4.1, the total entropy of the universe increases as the universe expands, as required by the second law.
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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, the
Planck time,
6.4 x 10
^–44
second 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 requires further elaboration. I seem to be saying that the entropy of the universe was maximal when the universe began, yet it has been increasing ever since. Indeed, that’s exactly what I am saying. When the universe began, its entropy was as high as 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 universe’s current size. The universe is no longer a black hole.

I also need to respond here to an objection that has been raised by physicists who have heard me make this statement. They point out, correctly, that we currently do not have a theory of quantum gravity that we can apply to describe physics earlier than the Planck time. I have adopted Einstein’s operational definition of time as what you read on a clock. In order to measure a time interval smaller than the Planck time, you would need to make that measurement in a region smaller than the Planck length, which equals the Planck time multiplied by the speed of light. According to the Heisenberg uncertainty principle of quantum mechanics, such a region would be a black hole, from which no information can escape. This implies that no time interval can be defined that is smaller than the Planck time.
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Consider the present time. Clearly we do not have any qualms about applying established physics “now” and for short times earlier or later, as long as we do not try to do so for time intervals shorter than the Planck time. Basically, by definition time is counted off as an integral number of units where one unit equals the Planck time. We can get away with treating time as a continuous variable in our mathematical physics, such as we do when we use calculus, because the units are so small compared to anything we measure in practice. We essentially extrapolate our equations through the Planck intervals within which time is unmeasurable and thus indefinable. If we can do this “now,” we can do it at the end of the earliest Planck interval where we must begin our description of the beginning of the big bang.

At that time, our extrapolation from later times tells us that the entropy was maximal. In that case, the disorder was complete and no structure could have been present. Thus, the universe began with no structure. It has structure today consistent with the fact that its entropy is no longer maximal.