The Underprivileged Universe

Victor J. Stenger

Draft of Wednesday, September 21, 2005 4:59 AM. For comments only. Do not copy or distribute.

A Privileged Planet?

In their book and documentary film The Privileged Planet, astronomer Guillermo Gonzalez and theologian Jay Richards present the now familiar argument that the universe is fine-tuned for the existence of human life and that this is evidence for intelligent design in the universe. In addition, they have provided a new slant. They argue that our place in the cosmos, the tiny planet Earth, was not only specially created for humanity but also designed for discovery.

Gonzalez and Richards contend that conditions on Earth, particularly those that make human life possible, are also optimized for scientific investigation and that this constitutes "a signal revealing a universe so skillfully created for life and discovery that it seems to whisper of an extraterrestrial intelligence immeasurably more vast, more ancient, and more magnificent than anything we've been willing to expect or imagine." They leave it to the reader to wonder what intelligence they have in mind.

Following the privileged-planet line of reasoning, the atmosphere of Earth is transparent in the visible spectral band not only so that humans can see with their eyes, but also so that astronomers can look through telescopes and thereby confirm the existence of a designer in the heavens.

Have you ever wondered why the angular diameter of the moon and sun as viewed from Earth are almost exactly the same, though the two celestial objects differ greatly in size and distance from Earth? Without that coincidence, we would never experience the type of total eclipse of the sun in which the sun’s disc is so precisely covered that we can view starlight near the rim. Gonzalez and Richards present this coincidence as a prime example of design for discovery.

Observations made during total eclipses have been used to verify a prediction of Einstein's theory of general relativity: the bending of starlight by the gravity of the sun. Gonzalez and Richards seem to think general relativity would not have been discovered (assuming the theories of physics are "out there" to be discovered) had we lived on a planet that did not exhibit this unlikely coincidence of angular diameters. This supposition is rather dubious, since many other tests of general relativity have been made that do not involve eclipses.

Gonzalez and Richards are Senior Fellows of the Center for Science and Culture, the arm of the Seattle-based Discovery Institute that is charged with the task of bringing science and culture into line with evangelical Christian teachings. With an ample supply of funding from rich, conservative sources the Center has used the political arena, with some success, to promote the notion that intelligent design in the universe can be detected by scientific means.

So far the emphasis has been on undermining the teaching of biological evolution in schools. The Privileged Planet represents a new move to claim evidence for intelligent design on the cosmic scale. We may anticipate legislatures and school boards will soon follow with proposals to include intelligent design in physics and astronomy classes.

A Waste of Space and Time

No doubt Earth is congenial to human life. But why would an intelligent designer with a presumed special interest in humanity build a vast universe with only a single, tiny planet suitable for human life? If the universe were designed with humans in mind, then you would expect it to be congenial to human life and make it easy for humans to develop and thrive throughout space.

But this does not appear to be the case. Earth is the only body capable of sustaining human life among nine or ten planets and countless moons and other objects in our solar system. On the planetary scale of human experience, the solar system is immense, extending billions of kilometers from the sun. Although the space between the planets contains smaller asteroids, comets, and dust, the solar system consists mainly of empty space that seems to serve no anthropocentric purpose.

Beyond the solar system we find even more space. The next closest star (after the sun), Proxima Centauri, is 40 trillion kilometers or 4.22 light years away.

Our sun and its planetary system are far from the center of a galaxy containing an estimated 200-400 billion other stars. These populate a flat, spiral disk 100,000 light-years across, and about 10,000 light-years thick called the Milky Way.

The Milky Way is but one of on the order of 100 billion galaxies in the visible universe. Andromeda, the next nearest galaxy other than two small satellite galaxies, is 2.44 million light years away.

And, you might ask, how big is the universe? The farthest observed galaxy at this writing, Abell 1835 IR1916, is 13.2 billion light years away. Since it has taken 13.2 billion years for its light to reach us, and the current estimate of the age of the universe is 13.7 billion years, we are seeing this galaxy as it was only 500 million years after the start of the big bang. Because of the expansion of the universe, Abell 1835 is now well beyond our visible horizon, where light takes longer than the age of the universe to reach us. Indeed, the region that now contains those galaxies that were once within our horizon extends an estimated 78 billion light-years in all directions.

Furthermore, as vast as all this is, cosmology suggests that a far vaster universe lies beyond. If the inflationary big bang model of the early universe is correct, then the universe beyond our horizon is larger than that within our view by a factor that is almost impossible to imagine. Here is one estimate of that factor: Write down the number 1 and follow it by 100 zeros. Then raise the number 10 to that power (10 to the 10¹⁰⁰).

In short, if the universe was designed for humanity, the designer seems to have wasted an awfully large amount of space where humanity will never make an appearance.

The designer wasted a lot of time, too. Instead of six days, he took nine billion years to make Earth, another billion years or so to make life, and then another four billion years to make humanity. Humans have walked on Earth for less than one hundredth of one percent of Earth's history.

A Waste of Matter and Energy

Let us next consider matter and energy. The visible matter in the hundred billion galaxies within our horizon, each with on the order of a hundred billion stars, is composed of "atomic matter," that is, chemical elements. These constitute just one-half of one percent of all the mass in the visible universe. Another 3.5 percent of the mass of the universe is of the same nature, only nonluminous. The remaining 96 percent is made up of still unidentified substances dubbed dark matter and dark energy. Even more striking, 99.5 percent of the mass of the universe is contained in matter that is not even visible to our eyes and optical telescopes.

Energy is wasted, too. Of all the energy emitted by the sun, only two photons in a billion are used to warm Earth, the rest radiating into space.

A Tiny Pocket of Complexity

It is commonly thought that the universe is an intricately complex place. This is a selection effect resulting from the fact that we and our planet are relatively complex. Most of the matter and energy of the universe, however, exhibits little structure and shows no sign of design.

The very low energy photons in the cosmic microwave background radiation are a billion times more plentiful than the atoms in galaxies. These particles are spread uniformly throughout the universe to one part in a hundred thousand. They move around almost completely randomly, as if they formed a gas in thermal equilibrium having maximum entropy and at a temperature only three degrees Kelvin above absolute zero. The little structure that is seen is easily understood as the remnant of random fluctuations that took place in the early universe and helped trigger galaxy formation. Today the cosmic microwave background is decoupled from the rest of the universe, having no significant effect on life or anything else.

Although virtually impossible to detect, we believe that an even greater number of very low energy neutrinos left over from the big bang is likewise randomly distributed throughout the universe and likewise has no effects. Since 0.03 percent of atoms are carbon, the main element of life, the universe contains only one carbon atom for every 3 trillion photons and perhaps every 10 trillion neutrinos. Yet we are supposed to believe that the universe was designed to manufacture carbon. All these useless photons and neutrinos are more credibly a signal of the absence of design.

Perhaps any largely random universe, regardless of its properties, will naturally develop at least a few tiny pockets of complexity within a vast sea of randomness, which is just what we seem to see in our universe. We do not need a designer to explain such rare deviations as are consistent with chance.

If matter was designed with human life in mind, not much of it is used for this purpose. In fact, the universe does not contain much complex order of any kind. It is mostly particles in random motion. The observed universe and the laws and parameters of physics look just as they can be expected to look if there is no design.

Humanity in Space

Much is made of human space flight. It is hyped as the search for new worlds akin to the European explorations on Earth during the Age of Discovery. Space operas like Star Trek and Star Wars lead people to think that someday all we will have to do is hop in a spaceship and cross the galaxy at warp speed. Every planet we land on is imagined to have an atmosphere and other conditions sufficiently like Earth that we will be able to walk around without spacesuits. In this way, it is widely thought, humanity will gradually populate the cosmos. But, as we have already seen, virtually the entire universe is already beyond our horizon and inaccessible even to spaceships traveling at near the speed of light.

Astronomers have surveyed all the normal (main sequence) stars out to a distance of about 100 light years from Earth and found about ten percent have planets. Of the hundred or so extrasolar planets discovered so far, not one is close to being suitable for life as we know it. This is most likely a selection effect favoring giant planets and it is reasonable to assume that each of these planetary systems also has smaller planets that might support some kind of life. However, most of the planetary systems studied so far bear little resemblance to our solar system. Even in the solar system, planets like Earth are the exception rather than the rule. The very fact that the powerful instruments of modern science, which can peer inside nuclei and out to the edge of the visible universe, have yet to find an earthlike planet around a sun-like star is already strong testimony that the galactic space around Earth is not exactly teeming with planets suitable for human habitation.

The data imply that on the order of ten billion stars in the Milky Way may have planetary systems. While some form of life might have evolved in a large fraction of these systems, the very reasons that Gonzalez and Richards give for Earth being “privileged” make it very unlikely that humans could survive without extensive life-support on any planet besides Earth.

The best any future star trekkers can hope for would be to find an advanced civilization that would take them in and provide life support. Colonization of other planets by earthlings is almost surely an impossible dream.

Perhaps future technologies will solve the problem. Maybe genetic engineering will make new kinds of humans, really a new species, suitable for space travel. And, we can always send automatons. Our descendants, genetically engineered or made of titanium and silicon, unhampered by our brief life spans may reach other planets. And we can hope they will be smarter, kinder, more rational, and free of the superstitions that plague us and make our very survival for just a few more centuries problematic.

Of course, sci-fi enthusiasts will accuse me of lack of imagination. Perhaps someday we will be able to travel through wormholes or warp space-time in Enterprise fashion. But, whatever fantastic discoveries are made in the future, there is no escaping the conclusion that the universe is very uncongenial to human life. Even taking the most optimistic view of the future of humankind or its progeny, we can be sure that the universe has not been designed to make it easy for humans to populate it. It is hard to conclude that the universe was created with a special, cosmic purpose for humanity. The data strongly suggest otherwise. Indeed, the universe looks very much like it was produced with no attention whatsoever paid to humanity. We may live on a privileged planet, but it is an insignificant speck in an underprivileged universe.