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The first big science bonus was paid to a man named Chou Yengbo, and he might not have earned it if he hadn't happened to have taken a few elementary science courses before he discovered that even a college degree couldn't get you a decent job, those days, in Shensi Province.

When Chou's ship came out of the faster-than-light drive, Chou had no trouble figuring out which objects the Heechee had set the controls for.

Actually there were three objects in view. They were weird. The first was wholly unlike anything Chou had ever seen before, even in the holograms of his astronomy course. It wasn't quite like anything any other human being had ever seen before, either, except in imagination. The object was an irregular, cone-shaped splash of light, and even on the viewscreen its colors hurt his eyes. 

What the thing looked like was a searchlight beam fanning out through patches of mist. When Chou looked more carefully, magnifying the image, he saw that there was another beam like it, sketchier and fainter and fanning out in the opposite direction. And between the two points of the cones formed by those beams, the third object was something almost too tiny to see.

When he put the magnification up to max, he saw that that something was a puny-looking, unhealthily colored little star.

It was much too small to be a normal star. That limited the possibilities; even so, it took Chou some time to realize that he was in the presence of a pulsar.

Then those Astronomy 101 lessons came back to him. It was Subrahmanyan Chandrasekhar, back in the middle of the twentieth century, who had calculated the genesis of neutron stars. His model was simple. A large star, Chandrasekhar said, uses up its hydrogen fuel and then collapses. It throws off most of the outer sections of itself as a supernova. What is left falls in toward the star's center, at almost the speed of light, compressing most of the star's mass into a volume smaller than a planet-smaller, in fact, than some mountains. This particular sort of collapse can only happen to big stars, Chandrasekhar calculated. They had to be 1.4 times as massive as Earth's Sun, at least, and so that number was called Chandrasekhar's Limit.

After that supernova explosion and collapse has happened, the object that remains—star heavy, asteroid sized—is a "neutron star." It has been crushed together so violently by its own immense gravitation that the electrons of its atoms are driven into its protons, creating the chargeless particles called neutrons. Its substance is so dense that a cubic inch of it weighs two million tons or so; it is like compressing the hugest of Earth's old supertankers into something the size of a coin. Things do not leave a neutron star easily; with that immense, concentrated mass pulling things down to its surface, escape velocity becomes something like 120,000 miles a second. More than that: its rotational energy has been "compressed," too. The blue-white giant star that used to turn on its axis once a week is now a superheavy asteroid-sized thing that whirls around many times a second.

Chou knew there were observations that he had to make—magnetic, X-ray, infrared, and many others. The magnetometer readings were the most important. Neutron stars have superfluid cores and so, as they rotate, they generate intense magnetic fields—just like the Earth. Not really just like the Earth, though, because the neutron star's magnetic field, too, is compressed. It is one trillion times stronger than the Earth's. And as it spins it generates radiation. The radiation can't simply flow out from all parts of the star at once—the lines of magnetic force confine it. It can only escape at the neutron star's north and south magnetic poles.

The magnetic poles of any object aren't necessarily in the same place as its poles of rotation. (The Earth's north magnetic pole is hundreds of miles away from the point where the meridians of longitude meet.) So all the neutron star's radiated energy pours out in a beam, around and around, pointing a little, or sometimes a lot, away from its true rotational poles.

So that was the explanation of the thing Chou was seeing. The cones were the two polar beams from the star that lay between them, north and south, fanning out from its poles. Of course, Chou couldn't see the beams themselves. What he saw were the places where they illuminated tenuous clouds of gas and dust as they spread out.

The important thing to Chou was that no Earthly astronomer had ever seen them that way. The only way anyone on Earth ever could see the beam from a neutron star was by the chance of being somewhere along-the rim of the conical shape the beams described as they rotated. And then what they saw was a high-speed flicker, so fast and regular that the first observer to spot one thought it was the signal from an alien intelligence. They called the signal an "LGM" (for Little Green Men) until they figured out what was causing that sort of stellar behavior.

Then they called the things "pulsars."

Chou got a four-hundred-thousand-dollar science bonus for what he had discovered. He wasn't greedy. He took it and returned to Earth, where he found a new career lecturing to women's clubs and college audiences on what it was like to be a Heechee prospector. He was a great success, because he was one of the first of the breed to return to Earth alive.

Later returnees were less fortunate. For instance, there was—



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