Prologue

500,000 B.C.

Buu lay in his leafy arbor nest and looked up at the stars in the dark sky. The hairy young humanoid should have been asleep, but his curiosity kept him awake. A half-million years in the future that twinkling of curiosity would have led his mind out into the universe to explore the mathematical mysteries of relativity. Now…

Buu continued to stare at the bright stars above him. One speck suddenly flared brighter. Frightened—but fascinated—Buu watched the growing point of intense light until it went behind a dense tree branch. He would be able to see it again if he went to the nearby clearing. He clambered down from his nest—into the striped coils of Kaa.

Kaa did not enjoy his kill for long. Things were difficult for him in a world with two suns. The new sun was tiny and white, while the old one was big and yellow. The new sun circled constantly overhead. It never set, and he could no longer catch things at night. Kaa died—along with other hunters who could not change their habits fast enough.

For a year the new light shone from above, searing the sky. Then it slowly grew dimmer and dimmer, and within a few years night returned to the northern hemisphere of Earth.

Fifty light-years away from the Solar System there was once a binary star system. One star was in its normal yellow-white phase, but the other had bloated up until it turned into a red giant, swallowing the planets around it. The nuclear fuel for the red giant ran out just fifty years before Buu’s curiosity got the better of him. With its fusion-bomb center turned off, the energy the star needed to hold itself up against its self-gravitation was no longer available, and the star collapsed. At the center, the in-falling matter became denser under the terrific gravitational pressure until it turned almost completely into neutrons. The neutrons pressed closer and closer until they were packed radius to radius.

Under these cramped conditions, the strong nuclear repulsion forces were finally able to resist the gravitational pressure. The inward rush of matter was quickly reversed, and the outward motion turned into an incandescent shock wave that traveled upward through the outer shell of the red giant. At the surface, the shock wave blew off the outer layers of the star in a supernova explosion that released more energy in one hour than the star had released in the previous million years.

Beneath the expanding cloud of blazing plasma, the core of the red giant had changed. What had once been a large, red, slowly rotating balloon 200 times bigger than the Sun was now a tiny, white-hot twenty-kilometer ball of ultra-dense neutrons, spinning at over 1000 revolutions a second.

The original magnetic field of the star had stayed trapped in the highly conductive collapsing cloud of star stuff. Like the sunspot pattern on the original star, the magnetic field was not aligned with the spin axis of the neutron star, but was sticking out at an odd angle. One magnetic pole was very concentrated and a little above the equator. The other (really a group of poles) was on the opposite side of the star. Part of its complex pattern was below the equator, but most of it was in the northern hemisphere.

The almost solid trillion-gauss magnetic fields reaching out from the two magnetic poles of the rapidly spinning star tore into the glowing debris remaining from the supernova explosion. Driven by the rapid rotation of the ultra-dense sphere, the magnetic fields threw the massive clouds of ions away from the star in scintillating gouts. Like a Fourth-of-July pinwheel on the loose, the neutron star accelerated off to the south, directly toward its nearby neighbor Sol, the magnetic propeller leaving a glowing wake streaming out behind. After a short while, the plasma density became thinner and the rocket action stopped, but by then the star had achieved a respectable proper motion of thirty kilometers per second or one light-year every 10,000 years, a tiny wanderer jaywalking across the star lanes of the Galaxy.

495,000 B.C.

As the neutron star spun its way through space, the debris it attracted by its gravitational field fell inward. When the interstellar material approached to within a few thousand kilometers of the twenty-kilometer-diameter ball, it was heated and stripped of its electrons by the intense gravity and the whirling magnetic fields. The ionized plasma then fell in elongated blobs toward the star, its velocity reaching one-quarter of the speed of light as it struck the crust in the east and west magnetic polar regions. The bombarded crust responded with flares of charged particles that shot back out into space, gaining speed and radiating pulses of radio energy as the spinning magnetic field lines whipped them outward.

Inflated by the pulsating radiation and streams of hot plasma from the spinning star, the cloud of gas from the original supernova explosion continued to expand at a speed of one percent that of light. After 5000 years, the front of the shock wave passed through the Solar System. For a thousand years the shielding magnetic fields of the Sun and Earth were buffeted by the invisible hurricane-force interstellar winds. The wiggling magnetic field lines lost their ability to keep the dangerous high-energy cosmic ray particles away from the fragile Earth. The ozone layer in the upper atmosphere collapsed, and the life forms on Earth were subjected to a harrowing barrage of mutating radiation.

When the millennia-long storm finally waned, a new species of nearly hairless humanoids had emerged on earth. The original band was small, but the individuals were smart. They used their intelligence to control things around them, instead of letting nature and the strong-muscled have their way. It wasn’t too long before their ancestors were the only humanoids left on the planet.

3000 B.C.

Traveling at its leisurely pace of one light-year every 10,000 years, the neutron star began to approach the Solar System. The intelligent beings who had been born in its baptism of invisible fire a half-million years ago had progressed to the point at which they began seriously to study the heavens. The neutron star glowed with a white-hot heat, but it was too tiny to be seen by mere human eyes.

Although many times hotter than the Sun, the neutron star was not a hot ball of gas. Instead, the 67-billion-gee gravity field of the star had compressed its blazing matter into a solid ball with a thick crust of close-packed, neutron-rich nuclei arranged in a crystalline lattice over a dense core of liquid neutrons. As time passed, the star cooled and shrank. The dense crust fractured and mountains and faults were pushed up. Most crustal features were only a few millimeters high, but the larger mountain ranges rose up almost ten centimeters, poking their tops above the iron-vapor atmosphere. The mountains were the highest at the east and west magnetic poles, for most of the meteoric material that fell on the star was directed there by the magnetic field lines.

The temperature of the star had fallen since its birth. The neutron-rich nuclei on the glowing crystalline crust could now form increasingly more complex nuclear compounds. Since the compounds utilized the strong nuclear interaction forces instead of the weak electronic molecular forces that were used on Earth, they worked at nuclear speeds instead of molecular speeds. Millions of nuclear chemical combinations were tried each microsecond instead of a few per microsecond, as on Earth. Finally, in one fateful trillionth of a second, a nuclear compound was formed that had two very important properties: it was stable, and it could make a copy of itself.

Life had come to the crust of the neutron star.

1000 B.C.

Still unseen by human eyes, the white-hot neutron star continued to approach the Solar System. As the surface of the star began to cool through that small temperature range that was most conducive to nucleonic life, the original replicating nuclear molecule diversified and became more complex. Competition for the simpler nonliving molecules that served as food became more intense. Soon the primordial manna that had covered the crust was gone, and in its place were clumps of hungry cells. Some clumps of cells found that their topsides, which faced outward toward the cold, dark sky, were constantly at a lower temperature than their undersides, which were in contact with the glowing crust. They raised a canopy of skin up away from the crust and soon were running an efficient food-synthesis cycle using the heat engine that they had arranged between a stiff taproot penetrating deep into the hot crust and the cool canopy above.

The canopy was a marvel of engineering. It used stiff crystals embedded with superstrong fibers to form a twelve-pointed cantilever beam structure that raised the thin upper skin against the 67-billion-gee gravity field of the star. Of course, a plant’s beam-structure couldn’t lift its topside very far. A plant might be as much as five millimeters across, but it could only raise a canopy up a millimeter.

The plants paid a price for their canopies and supporting frame. They were rigid and had to stay where they had rooted. For many, many turns of the star, nothing moved except for an occasional spray of pollen from the tip of a cantilever beam on one plant, followed by the contraction of a flap at the tip of a nearby plant. Then, many turns later, that action would be followed by the dropping of a ripe seed pod, which rolled away in the continual winds.

One turn, a rolling seed pod broke against a chunk of crust. Its seeds scattered and several of them started to grow. One was more vigorous than the others, and soon its canopy began to rise above those of its slower siblings. Suffocated in the heat radiated from the star below and the underside of the taller plant above, most of the smaller seedlings died.

One, however, underwent a strange transformation as its body functions started to fail. It had a mutant enzyme whose normal function was the fabrication and repair of the crystalline structure that held up the canopy. But under the influence of the distorted nucleonic chemistry of an organism near death, the enzyme went wild and dissolved the crystalline structure it was designed to protect. The plant turned into a sac full of juice and fibers, and flowed down the slight slope upon which it had been rooted to a new resting place. The twelve pollen sprayers, slightly photosensitive in order to provide the optimum orientation for the canopy of the plant, worked their way around to the top. Now that the organism was out from under the blocking canopy of the larger plant, the errant enzyme controlled itself again. The plant sent down roots, rebuilt its canopy, and proceeded to give and receive many sprays of pollen. The mobile plant had many seedlings, all of which had the ability to dissolve their rigid structure and move if the conditions weren’t right for optimum growth.

Soon the first animals roamed the surface of the neutron star, stealing seed pods from their immobile cousins and learning that there were many good things to eat on the star—especially each other.

Like the plants they came from, the neutron star animals were only five millimeters across, but, lacking stiff internal structures, they were flattened by the gravitation. The twelve photosensitive pollen sprayers and flaps became eyes, but they still retained their original reproduction function. The animals could grow “bones” whenever they wished. Most of the time these were degenerate forms of the cantilever beams that were used to hold their eyes up on stalks so they could see further; but, with a little concentration, a bone could be formed anywhere inside the skin sac. However, speed of bone forming was paid for in quality: the bones were made solely of crystallized internal juices; they did not contain the embedded fibers that made the plant structure so strong. That procedure took too much time.

Unlike the plants, the animals had to contend with the star’s magnetic field. The plants didn’t move, so they didn’t mind that they were stretched into a long ellipse aligned along the magnetic field lines. The bodies of the animals were also stretched into long ellipses, but since their eyes were stretched by the same amount, they were not aware of the distortion. However, the animals found that it was much harder to move across the magnetic field lines than along them. Most gave up trying. To them the world was nearly one-dimensional. The only easy directions in which to travel were “east” and “west”—toward the magnetic poles.

After a long time, plants and animals existed all over the surface of the neutron star. Some of the smarter animals would look up at the dark sky and wonder at the points of light they saw moving slowly across the blackness as the neutron star turned. The animals in the southern hemisphere of the star were especially bewildered by the very bright spot of light that stayed fixed over the south pole. It was Earth’s Sun. The light was so bright and close that it didn’t twinkle like the other specks of light. But except for using the star as a convenient navigation beacon to supplement their magnetic directional sense, none of the animals bothered to think more about the strange light. There was always plenty of food from the constantly growing plants and the smaller animals. An animal doesn’t need to develop curiosity and intelligence if it has no problems that need solving.

2000 A.D.

The blinking, radiating, spinning neutron star was now one-tenth of a light year from the Sun. After a half-million years the star had cooled, and its spin speed had slowed to only five revolutions per second. It still sent out pulses of radio waves, but these were but a weak remembrance of its brilliant earlier days.

In a few hundred more years the neutron star would pass by the solar system at a distance of 250 astronomical units. Its gravity would perturb the outer planets, especially Pluto, way out at 40 AU from the sun. But Earth, snuggled up to Sol in its orbit of one AU radius, would scarcely notice the passage. The star would then leave the Solar System—never to return.

By now the life forms on Earth had invented the telescope, but even this was inadequate to see the tiny pinpoint of light in the vast heavens unless one knew exactly where to look.

Would it pass unseen?