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used was "glorious"-a globular cluster, with thousands of bright stars
interweaving their orbits in a volume a few hundred light-years across. It was
certainly spectacular. It dominated the sky. It was much nearer to them than
any such object had ever been to a human eye before. But it was still at least
a thousand light-years away.
A globular cluster is an inspiring sight. It was a long way from Sakyetsu and
his ship Victory, but by the standards of Earthly astronomers that was nothing
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at all. Globular clusters live on the outer fringe of the galaxy. There aren't
any in the crowded spiral-arm regions like the neighborhood of Earth. There
are almost none less than twenty thousand light-years from Earth, and here was
one a twentieth as far-and thus, by the law of inverse squares, four hundred
times as bright. It was not an unusually large specimen, as globular clusters
go; the big ones run upward of a million stars, and this one was nowhere near
that. It was big enough to be exciting to look at, all the same.
But it was neither big enough nor near enough for Victory's instruments to
reveal any more than Earth's own orbiting observatories, with their far more
powerful mirrors and optical systems, had seen long ago.
So there was very little chance that the instruments on Victory could earn
them any kind of decent bonus. Still, those instruments were all they had. So
the crew doggedly put them to work. They photographed the cluster in red
light, blue light, ultraviolet light, and several bands of the infrared. They
measured its radio flux in a thousand frequencies, and its gamma rays and X-
rays. And then, one sleeping period, while only H~tl M'Buna was awake at the
instruments, he saw the thing that made the trip worthwhile.
His shout woke everybody up. "Something's eating the cluster!"
Marianna Morse was the first to get to the screens with him, but the whole
crew flocked to see. The fuzzy circle of the cluster wasn't a circle anymore.
An arc had been taken out of its lower rim. It looked like a cookie a child
had bitten into.
But it wasn't a bite.
As they watched, they could see the differences. The stars of the cluster
weren't disappearing. They were just, slowly, moving out of the way of-
something.
"My God," Marianna whispered. "We're in orbit around a black hole."
Then they cursed the week they had wasted, because they knew what that meant.
Big money! A black hole. One of the rarest objects (and, therefore, one of the
most highly rewarded in science bonuses) in the observable universe-because
black holes are, intrinsically, unobservable.
A black hole isn't "black," in the sense that a dinner jacket or the ink on a
piece of paper is black. A black hole is a lot blacker than that. No human
being has ever seen real blackness, because blackness is the absence of all
light. It can't be seen. There is nothing to see. The blackest dye reflects a
little light; a black hole reflects nothing at all. If you tried to illuminate
it with the brightest searchlight in the universe-if you concentrated all the
light of a quasar on it in a single beam-you would still see nothing. The
tremendous gravitational force of the black hole would suck all that light in
and it would never come out again. It can't.
It is a matter of escape velocity. The escape velocity from the Earth is seven
miles a second; from a neutron star as much as 120,000 miles per second. But
the escape velocity from a black hole is greater than the speed of light. The
light doesn't "fall back" (as a rock thrown up from Earth at less than escape
velocity will fall back to the ground). What happens to the light rays is that
they are bent by the gravitational pull. The radiation simply circles the
black hole, spiraling endlessly, never getting free.
And when a black hole passes in front of, say, a globular cluster, it doesn't
hide the cluster. It simply bends the cluster's light around it.
If Victory's crew had wasted seven days, they still had five days' worth of
supplies left before they had to start back to Gateway. They used them all.
They took readings on the black hole even when they couldn't see it ... and
when at last they got back to Gateway they found that one, just one, of their
pictures had paid off.
They shared a five-hundred-thousand-dollar bonus simply for the pictures of
the globular cluster. But the one picture that they hadn't even noticed when
they took it-a split-second frame, taken automatically when no one happened to
be watching the screen- showed what happened when the black hole occluded a
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bright B-4 star, a few hundred light-years away. That star hadn't moved up or
down. By chance it had passed almost exactly behind the black hole. Its light
had spread to surround the hole, like a halo; and that gave them a measure of
the hole's size .
And then, long after they were back in Gateway, the research teams that
studied their results awarded them another half a million, and the information
that they were very lucky.
Marianna Morse had wondered about that: Why had the Heechee used an armored
Five to visit this harmless object? Answer: It hadn't always been harmless.
Most black holes are not safe to visit. They pull in gases in accretion rings,
and the acceleration of the gases as they fall produces a hell of radiation.
Once this one had, but that was a long time ago. Now it had eaten all the
gases in its neighborhood. There was nothing left to fall and so generate the
synchrotron flux of energy that might fry even an armored Five if it lingered
too long nearby .
and so the crew of Victory, without knowing it at the time, had had an
unexpected stroke of luck. They arrived at the neighborhood of their black
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