more work. Paraffin is a solid that's largely
hydrogen. That's what they've always used on neutrons since they
discovered them. Confine your paraffin between tungsten walls, and
you'll stop the secondary protons as well as the neutrons."

"Hmmm--I suppose so. How about seeing those physicists?"

"I'd like to see them today, sir. The sooner you get started on this
work, the better it will be for the IP."

"Having seen me, will you join up in the IP again?" asked McLaurin.

"No, sir, I don't think I will. I have another field you know, in which
I may be more useful. Cole here's a better technician than fighter--and
a darned good fighter, too--and I think that an inexperienced
space-captain is a lot less useful than a second-rate physicist at work
in a laboratory. If we hope to get anywhere, or for that matter, I
suspect, stay anywhere, we'll have to do a lot of research pretty
promptly."

"What's your explanation of that ship?"

"One of two things: an inventor of some other system trying out his
latest toy, or an expedition sent out by a planetary government for
exploration. I favor the latter for two reasons: that ship was _big_. No
inventor would build a thing that size, requiring a crew of several
hundred men to try out his invention. A government would build just
about that if they wanted to send out an expedition. If it were an
inventor, he'd be interested in meeting other people, to see what they
had in the way of science, and probably he'd want to do it in a
peaceable way. That fellow wasn't interested in peace, by any means. So
I think it's a government ship, and an unfriendly government. They sent
that ship out either for scientific research, for trade research and
exploration, or for acquisitive exploration. If they were out for
scientific research, they'd proceed as would the inventor, to establish
friendly communication. If they were out for trade, the same would
apply. If they were out for acquisitive exploration, they'd investigate
the planets, the sun, the people, only to the extent of learning how
best to overcome them. They'd want to get a sample of our people, and a
sample of our weapons. They'd want samples of our machinery, our
literature and our technology. That's exactly what that ship got.

"Somebody, somewhere out there in space, either doesn't like their home,
or wants more home. They've been out looking for one. I'll bet they sent
out hundreds of expeditions to thousands of nearby stars, g