Cheaper than printing it out: buy the paperback book.

I head up the hill behind my house one more time. I ramble over to a grove of eucalyptus trees, where the local 4-H club used to keep its beehives. The grove snoozes in moist shade this time of day; the west-facing hill it stands on blocks the warm morning sun.

I imagine the valley all rock and barren at history's start-a hill of naked flint and feldspar, desolate and shiny. A billion years flicker by. Now the rock is clothed with a woven mat of grass. Life has filled a space in the grove with wood reaching higher than I can. Life is trying to fill the whole valley in. For the next billion years, it will keep trying new forms, erupting in whatever crevice or emptiness it can find.

Before life, there was no complex matter in the universe. The entire universe was utterly simple. Salts. Water. Elements. Very boring. After life, there was much complex matter. According to astrochemists, we can't find complex molecules in the universe outside of life. Life tends to hijack any and all matter it comes in contact with and complexify it. By some weird arithmetic, the more life stuffs itself into the valley, the more spaces it creates for further life. In the end, this small valley along the northern coast of California will become a solid block of life. In the end, left to its own drift, life may infiltrate all matter.

Why isn't the Earth a solid green from space? Why doesn't life cover the oceans and fill the air? I believe the answer is that if left alone, the Earth will be solid green someday. The conquest of air by living organisms is a relatively recent event, and one not yet completed. The complete saturation of the oceans may have to wait for rugged mats of kelp to evolve, ones able to withstand storm waves. But in the end, life will dominate; the oceans will be green.

The galaxy may be green someday too. Distant planets now toxic to life won't always remain so. Life can evolve representations of itself capable of thriving in environments that seem hostile now. But more importantly, once one variety of life has a toehold in a place, the inherently transforming nature of life modifies the environment until it is fit for other species of life.

In the 1950s, the physicist Erwin Schrödinger called the life force "negentropy" to indicate its opposite direction from the push of thermal decay. In the 1990s, an embryonic subculture of technocrats thriving in the U.S. calls the life force "extropy."

"Extropians," as promoters of extropy call themselves, issued a seven-point lifestyle manifesto based on the vitalism of life's extropy. Point number three is a creed that states their personal belief in "boundless expansion"-the faith that life will expand until it fills the universe. Those who don't believe this are tagged "deathists." In the context of their propaganda, this creed could be read as mere pollyanna self-inspiration, as in: We can do anything!

But somewhat perversely I take their boast as a scientific proposition: life will fill the universe. Nobody knows what the theoretical limits to the infection of matter by life would be. Nor does anybody know what the maximum amount of life-enhanced matter that our sun could support is.

In the 1930s, the Russian geochemist/biologist Vernadsky wrote, "The property of maximum expansion is inherent to living matter in the same manner as it is characteristic of heat to transfer from more heated to less heated bodies, of a soluble substance to dissolve in a solvent, and of a gas to dissipate in space." Vernadsky called it "pressure of life" and measured this expansion as velocity. His record for the velocity of life expansion was a giant puffball, which, he said, produced spores at such a rate that if materials were provided fast enough for the developing fungus, in only three generations puffballs would exceed the volume of Earth. He calculated by some obscure method that the life force's "speed of transmission" in bacteria is about 1,000 kilometers per hour. Life won't get far in filling up the universe at that rate.

When reduced to its essentials, life is very close to a computational function. For a number of years Ed Fredkin, a maverick thinker once associated with MIT, has been spinning out a heretical theory that the universe is a computer. Not metaphorically like a computer, but that matter and energy are forms of information processing of the same general class as the type of information processing that goes on inside a Macintosh. Fredkin disbelieves in the solidity of atoms and says flatly that "the most concrete thing in the world is information." Stephen Wolfram, a mathematical genius who did pioneering work on the varieties of computer algorithms agrees. He was one of the first to view physical systems as computational processes, a view that has since become popular in some small circles of physicists and philosophers. In this outlook the minimal work accomplished by life resembles the physics and thermodynamics of the minimal work done in a computer. Fredkin and company would say that knowing the maximum amount of computation that could be done in the universe (if we considered all its matter as a computer) would tells us whether life will fill the universe, given the distribution of matter and energy we see in the cosmos. I do not know if anyone has made that calculation.

One of the very few scientists to have thought in earnest about the final destiny of life is the theoretical physicist Freeman Dyson. Dyson did some rough calculations to estimate whether life and intelligence could survive until the ultimate end of the universe. He concluded it could, writing: "The numerical results of my calculations show that the quantities of energy required for permanent survival and communication are surprisingly modest....[T]hey give strong support to an optimistic view of the potentialities of life. No matter how far we go into the future, there will always be new things happening, new information coming in, new worlds to explore, a constantly expanding domain of life, consciousness and memory."

Dyson has taken this further than I would have dared. I was merely concerned about the dynamics of life, and how it infiltrates all matter, and how nothing known can halt it. But just as life irretrievably conquers matter, the lifelike higher processing power we call mind irrevocably conquers life and thus also all matter. Dyson writes in his lyrical and metaphysical book, Infinite in All Directions:

It appears to me that the tendency of mind to infiltrate and control matter is a law of nature....The infiltration of mind into the universe will not be permanently halted by any catastrophe or by any barrier that I can imagine. If our species does not choose to lead the way, others will do so, or may have already done so. If our species is extinguished, others will be wiser or luckier. Mind is patient. Mind has waited for 3 billion years on this planet before composing its first string quartet. It may have to wait for another 3 billion years before it spreads all over the galaxy. I do not expect that it will have to wait so long. But if necessary, it will wait. The universe is like a fertile soil spread out all around us, ready for the seeds of mind to sprout and grow. Ultimately, late or soon, mind will come into its heritage. What will mind choose to do when it informs and controls the universe? That is a question which we cannot hope to answer.