The Portable Atheist: Essential Readings for the Nonbeliever

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 kalam cosmological argument, which is drawn from Islamic theology.[46] 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 kalam argument has been severely challenged by philosophers on logical grounds,[47] 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. That’s 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 “caused,” just caused in a nonpredetermined manner—what he calls “probabilistic causality.” In effect, Craig is thereby admitting that the “cause” in his first premise could be an accidental one, something spontaneous—something not predetermined. By allowing probabilistic cause, he destroys his own case for a predetermined creation.

We have a highly successful theory of probabilistic causes—quantum 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.[48] This assumes the existence of yet-undetected subquantum forces. While this interpretation has some supporters, it is not generally accepted because it requires superluminal connections that violate the principles of special relativity.[49] More important, no evidence for subquantum 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 theory—including Bohm’s—can 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 “law.” 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 distinct 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.[50] 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 kalam conclusion were sound and the universe had a cause, why could that cause itself not be natural? As it is, the kalam argument fails both empirically and theoretically without ever having to bring up the second premise about the universe having a beginning.

The Origin

Nevertheless, another nail in the coffin of the kalam 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 preexisting one, for example, by a process called quantum tunneling or so-called quantum fluctuations.[51] 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.

In The Comprehensible Cosmos, I presented a specific scenario for the purely natural origin of the universe, worked out mathematically at a level accessible to anyone with an undergraduate mathematics or physics background.[52] This was based on the no boundary model of James Hartle and Stephen Hawking.[53] In that model, the universe has no beginning or end in space or time. In the scenario I presented, our universe is described as having “tunneled” through the chaos at the Planck time from a prior universe that existed for all previous time.

While he avoided technical details in A Brief History of Time, the no boundary model was the basis of Hawking’s oft-quoted statement: “So long as the universe had a beginning, we could suppose it had a creator. But if the universe is really completely self-contained, having no boundary or edge, it would have neither beginning nor end; it would simply be. What place then, for a creator?”[54]

Prominent physicists and cosmologists have published, in reputable scientific journals, a number of other scenarios by which the universe could have come about “from nothing” naturally. [55] None can be “proved” at this time to represent the exact way the universe appeared, but they serve to illustrate that any argument for the existence of God based on this gap in scientific knowledge fails, since plausible natural mechanisms can be given within the framework of existing knowledge.

As I have emphasized, the God of the gaps argument for God fails when a plausible scientific account for a gap in current knowledge can be given. I do not dispute that the exact nature of the origin of the universe remains a g p in scientific knowledge.

But I deny that we are bereft of any conceivable way to account for that origin scientifically.

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, it follows that no creator exists who left a cosmological imprint of a purposeful creation.

Intervening in the Cosmos

This still leaves open the possibility that a god exists who may have created the universe in such a way that did not require any miracles and did not leave any imprint of his intentions. Of course, this is no longer the traditional Judeo-Christian-Islamic God, whose imprint is supposedly everywhere. But, perhaps those religions can modify their theologies and posit a god who steps in later, after the Planck time, to ensure that his purposes are still served despite whatever plans he had of creation being wiped out by the chaos at the Planck time.

In that case, we can again expect to find, in observations or well-established theories, some evidence of places where this god has intervened in the history of the cosmos. In previous chapters we sought such evidence on