God: The Failed Hypothesis (19 page)

Clearly we are not yet in a position to determine whether complex life is common or rare in the universe. However, the fact is that complex life exists on one planet, Earth. And that existence is not implausible, given the conditions we know exist in the universe.

Obviously, if the physical parameters of our environment were just slightly different, life as we know it on Earth would not have evolved here. But, since the universe contains hundreds of billions if not trillions of planets, then it would seem that the chance of finding one someplace with the right conditions for our kind of life would be pretty good. We just happen to live on one suitable planet, having evolved to survive under its specific conditions.

And, what about life that is
not
“as we know it”? It does not take a great stretch of the imagination to accept the possibility that an appreciable number of planets exist with conditions that, while unsuitable for our form of life, still can support some kind of life.

Is the Universe Fine-Tuned for Life?

While we do not find it surprising that life exists on at least one planet in our universe under the conditions of that universe, we might ask what would be the case if the universe had different conditions. Over the past three decades, theologians and some theistic scientists have introduced a novel argument for the existence of a god who created the universe with special attention to the presence of humanity in that universe. They ask: how can the universe possibly have obtained this unique set of constants, so exquisitely “fine-tuned” for life as they are, except by purposeful design—design with life and perhaps humanity in mind
¹¹
?

Of course, one might wonder why a perfect God would build a universe that was so delicately balanced. If he really designed it for life, you would think he could have made it a lot easier for life to evolve.

The fine-tuning arguments have been somewhat misleadingly categorized under the designation
anthropic principle,
a term coined by astronomer Brandon Carter in 1974
¹²
. Mathematician John Barrow and physicist Frank Tipler provided a detailed, scientific review in 1986
¹³
. I have also written much on the subject, in various books and papers
¹⁴
.

Many of the examples of fine-tuning found in theological literature suffer from simple misunderstandings of physics. For example, any references to the fine-tuning of constants like the speed of light,
c,
Planck’s constant,
h,
or Newton’s gravitational constant, G, are irrelevant since these are all arbitrary constants whose values simply define the system of units being used. Only “dimensionless” numbers that do not depend on units, such as the ratio of the strengths of gravity and electromagnetism, are meaningful.

Some of the “remarkable precision” of physical parameters that people talk about is highly misleading because it depends on the choice of units. For example, theologian John Jefferson Davis asserts, “If the mass of neutrinos were 5 × 10”34 instead of 5 × 10”35 kg [kilogram], because of their great abundance in the universe, the additional gravitational mass would result in a contracting rather than expanding universe
¹⁵
.” This sounds like fine-tuning by one part in 1035. However, as philosopher Neil Manson points out, this is like saying that “if he had been one part in 1016 of a light-year shorter (that is, one meter shorter), Michael Jordan would not have been the world’s greatest basketball player
¹⁶
.”

Furthermore, if the neutrinos were ten times more massive, there would be ten times fewer of them in the cosmos, so the gravitational effect would be unchanged. This fine-tuning example, like so many, collapses on several fronts. Philosopher Robert Klee has provided other examples of how numbers have been manipulated to make it seem that fine-tuning has occurred
¹⁷
.

In short, much of the so-called fine-tuning of the parameters of microphysics is in the eye of the beholder. Nevertheless, life
as we know it
on Earth would not exist if several of the parameters of physics were different from their existing values. Here are the most significant:

1. The electromagnetic force is 39 orders of magnitude stronger than the gravitational force. If the forces were more comparable in strength, stars would have collapsed long before life had a chance to evolve.

2. The vacuum energy density of the universe is at least 120 orders of magnitude lower than some theoretical estimates. If at any time the universe was as large as these calculations suggest, it would have quickly blown apart.

3. The electron’s mass is less than the difference in the masses of the neutron and proton. Thus, a free neutron can decay into a proton, electron, and antineutrino. 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.

4. The neutron is heavier than the proton, but not so much heavier that neutrons cannot be bound in nuclei, where conservation of energy prevents the neutrons from decaying. Without neutrons we would not have the heavier elements needed for building complex systems such as life.

5. The carbon nucleus has an excited energy level at around 7.65 million electron-volts (MeV). Without this state, insufficient carbon would be manufactured in stars to form the basis for life. Using anthropic arguments, astronomer Fred Hoyle predicted this energy level before it was confirmed experimentally
¹⁸
.

All these statements can be expressed in a unit-free way.

How Sign if I Can’t Is the Fine-Tuning?

Let us take a look at these parameters to see how significant is the fine-tuning. The strength of the electromagnetic force is determined by a dimensionless parameter
a
called the
fine structure constant,
which depends on the value of the unit electric charge, that is, the magnitude of the charge of an electron conventionally designated by
e
¹⁹
. The claim is that
a
has been fine-tuned far from its natural value in order that we have stars sufficiently long-lived for life to evolve (item 1 above).

However,
a
is not a constant. We now know from the highly successful standard model of particles and forces that
a
and the strengths of the other elementary forces vary with energy and must have changed very rapidly during the first moments of the big bang when the temperature changed by many orders of magnitude in a tiny fraction of a second. According to current understanding, in the very high-temperature environment at the beginning of the big bang, the four known forces were unified as one force. As was discussed in the previous chapter, the universe can be reasonably assumed to have started in a state of perfect symmetry, the symmetry of the “nothing” from which it arose. So,
a
began with its natural value; in particular, gravity and electromagnetism were of equal strength. That symmetry, however, was unstable and, as the universe cooled, a process called
spontaneous symmetry breaking
resulted in the forces separating into the four basic kinds we experience at much lower energies today, and their strengths evolved to their current values. They were not fine-tuned. Stellar formation and, thus, life had to simply wait for the forces to separate sufficiently. That wait was actually a tiny fraction of a second.

The forces continued to separate as the universe continued to cool, but this was so slow that for all practical purposes on a human timescale, the strengths of the various forces can be regarded as constant.

Only four parameters are needed to specify the broad features of the universe as it exists today: the masses of the electron and proton and the current strengths of the electromagnetic and strong interactions
²⁰
. (The strength of gravity enters through the proton mass, by convention.) I have studied how the minimum lifetime of a typical star depends on the first three of these parameters
²¹
. Varying them randomly in a range often orders of magnitude around their present values, I find that over half of the stars will have lifetimes exceeding a billion years. Large stars need to live tens of millions of years or more to allow for the fabrication of heavy elements. Smaller stars, such as our sun, also need about a billion years to allow life to develop within their solar system of planets. Earth did not even form until nine billion years after the big bang. The requirement of long-lived stars is easily met for a wide range of possible parameters. The universe is certainly not fine-tuned for this characteristic.

One of the many major flaws with most studies of the anthropic coincidences is that the investigators vary a single parameter while assuming all the others remain fixed. They further compound this mistake by proceeding to calculate meaningless probabilities based on the grossly erroneous assumption that all the parameters are independent
²²
. In my study I took care to allow all the parameters to vary at the same time.

Physicist Anthony Aguire has independently examined the universes that result when six cosmological parameters are simultaneously varied by orders of magnitude, and found he could construct cosmologies in which “stars, planets, and intelligent life can plausibly arise
²³
.” Physicist Craig Hogan has done another independent analysis that leads to similar conclusions
²⁴
. And, theoretical physicists at Kyoto University in Japan have shown that heavy elements needed for life will be present in even the earliest stars independent of what the exact parameters for star formation may have been
²⁵
.

The current standard model of elementary particles and forces contains about twenty-four parameters that currently are not determined by the theory but must be inferred from experiments.

This is not as bad as it might seem, since the model accurately describes thousands of data points. In any case, only four parameters are needed to specify most properties of matter. These are the masses of the electron and the two quarks (“up” and “down”) that constitute protons and neutrons, and a universal strength parameter from which the value
a
and the other force strengths are obtained. Ultimately, it is hoped that all the basic parameters will be determined by theories that unify gravity with the standard model, for example,
string theory
²⁶
.
We must wait to see if the calculated masses of the electron and neutron come out to satisfy coincidences 3 and 4 above.

Are Carbon and Organic Molecules Fine-Tuned?

Let us next take a more detailed look at coincidence 5, which asserts that fine-tuning is needed to produce carbon, the primary building block of life. Astronomer Fred Hoyle used anthropic arguments to successfully predict the presence of a nuclear energy level in carbon at 7.65 million electron-volts. However, M. Livio and collaborators have shown that the production of carbon in stars does not depend sensitively on that nuclear energy level.

Rather it hinges on the radioactive state of a carbon nucleus formed out of three helium nuclei, which misses being too high for carbon production by only 20 percent
²⁷
. Nobel laureate physicist Steven Weinberg has noted that this “is not such a close call after all
²⁸
.”

The chemical elements carbon and oxygen are among the easiest to produce in the nuclear reactions that take place in dying stars. The main energy source in stars is the fusion of hydrogen into helium. The helium nucleus, composed of two protons and two neutrons and symbolized by 2He4, is highly stable—as predicted by the rules of quantum mechanics
²⁹
. Two helium nuclei can fuse to give a beryllium nucleus, 2He4 + 2He4 -> 4Be8

Another helium then can fuse with the beryllium to produce carbon, 2He4 + 4Be8 -> 6C12

And yet another helium can fuse with the carbon to give oxygen, 2He4 + 6C12 -> 8O16

Each of these product nuclei is also very stable and so will survive indefinitely. When the star finally runs out of energy these elements among others in the periodic table, especially iron, are distributed into the space between stars, either by evaporation or, in the case of very massive stars, enormous explosions called supernovae
³⁰
.

In short, no fine-tuning is necessary for the production of carbon, oxygen, and the other basic elements of life. They are in fact the elements that are among the easiest to form by common nuclear reactions.

So, too, are the molecular ingredients of life easy to produce.

In a remarkably simple experiment in 1952, which took only weeks to assemble, graduate student Stanley Miller, working under the renowned chemist Harold Urey, sent a 60,000-volt electrical spark, simulating lightning, through a flask containing a gas of methane, ammonia, hydrogen, and water vapor. At the time, this was thought to simulate the atmosphere of early Earth.

The by-product contained amino acids, the basic chemical subunit of proteins, and other raw materials of life
³¹
.

We now know that Miller’s gas mixture did not accurately represent the Earth’s atmosphere at the likely time that life originated. Some theists have seized on this to dismiss the importance of the experiment
³²
. But, they miss the point, which is that the complex, carbon-based molecules that occur in living matter can be readily produced by chemical reactions involving simpler substances. This is another example of how simplicity can beget complexity, contrary to the claims of creationists.

Astrobiologists have now demonstrated that organic molecules occur under a wide range of conditions, including those that existed on the early Earth and those existing in space. Space origins are confirmed by the observation of these molecules in meteorites analyzed immediately after striking Earth so that effects of contamination by earthly matter are minimal. Perhaps the first ingredients of life came from space after Earth formed
³³
.