"Myself, I never could understand why a sensible man would go into that business. No money. No prestige. Never doing anything, just reading and thinking."

"Every man to his taste," said Larrabee.

"Yes, within limits. But the things some of you professors think up! Most of the ideas do more harm than good, scaring people to death, hurting business. You'd think they ought to have more sense of responsibility!"

He tasted his drink, then nodded knowingly at the bartender. "This is something like! Real absinthe."

Professor Larrabee studied his companion. "I can hardly suppose, Mr. Jasperson, that you hold professors responsible for all the ills of the world. And yet you seem disturbed. Did you have something in particular in mind?"

"Yes. The Thakura Ripples!"

Amusement vanished from the professor's eyes. "What about them?"

"Why are people so afraid of them? As far as I can see, they're just a piece of nonsense thought up by a dreamy-eyed physics professor, and he hypnotized people into believing in them. But as I was telling Captain Evans last night, they've never been seen, never been measured, and there's nothing at all to prove that they have any existence outside the mind of a madman. And yet people are afraid of them!"

"And just what are the Thakura Ripples?" said Alan Chase, drawing up a chair. "Waiter, I'll have a spacecap."

"Feeling a little better tonight, Alan?" asked his friend.

"Some, thanks. I just had a checkup from Dr. Willoughby, and he thinks I'm more than holding my own. Now go on about the Ripples. Where are they? What do they do?"

"Suit yourself," Jasperson muttered. "If you want to tell ghost stories, go ahead."

"Thank you. The Thakura Ripples, my boy, are an unexplained phenomenon of hyperspace. We do not know what they are—only that they are dangerous."

"But I thought that space was entirely uniform?"

"Alas, no. Not even normal space can be called uniform. It has been known for a long time that variations exist in the density of the interstellar gases. Just why they occur, what pattern they follow, if any, was for many years one of the major unsolved problems confronting astronomers and physicists. Then they learned that these variations in density of the interstellar gases were directly connected with the development of the successive ice ages on the earth, and eventually a study of the collisions and interactions of the various light forces from the stars in the galaxy made the pattern clear. We know, now, that the variations occur only in a certain band of space. They may occur at any given place within that band, but their position is constantly shifting and unpredictable."

"Now you see it, now you don't?" said Alan.

"Exactly. Now it was Thakura's theory that the Ripples are an analogous band of mysterious forces existing in hyperspace. They may be tangible barriers, they may be force barriers, we do not know. But a ship entering this lane may go through it without damage, and by pure chance take a course which misses all these bumps in space. Or, by going slowly and using his instruments to feel his way, a navigator can often sense them ahead, and if he is skillful he may be able to dodge them. But if, in some terrible moment, he smashes head-on against the Thakura Ripples, the conversion Piles which power his ship are immediately affected. They begin to heat, perhaps to heat irreversibly, and if they get out of control, they may vaporize. In the last fifty years at least five ships have vanished in this region, and it was Thakura's belief that they were disintegrated on the Ripples."

"But there isn't any evidence!" Jasperson exploded.

"Isn't a demolished space ship evidence?"

"No! It's evidence that something went wrong, certainly, but it doesn't tell us what went wrong. I'm not an unreasonable man, professor, I'm a hardheaded business man, and I like to deal with facts."

"I don't have an intimate knowledge of these matters, of course," said Larrabee, "but it was my impression that in the past fifty years since travel in hyperspace became common, several ships have been unaccountably lost."

"Your first figure was right. Five ships have been lost—that much is fact. Why they were lost is still a question. It's my considered opinion that they were lost by human failure; the crewmen let the Piles get hot, and the ships were helpless. In the early days they had to get along with only one or two Piles, and if they went wrong the ship was done for. But we've changed all that. That's why the Star Lord has twenty-four Piles. No matter what happens it's impossible that all of them should go bad at once. She can ditch the dangerous Piles and still always have power enough left to make port. One thing is certain, this ship will never be wrecked on the Ripples of a mad scientist's imagination! A phenomenon like the Ripples, is impossible. If it existed, we'd have had some proof of it many years ago."

"But surely you don't mean to imply that if we don't know a fact, it is therefore impossible?"

"Not at all. But you know yourself, Professor Larrabee—you're an educated man—that by this time our physicists understand the universe completely, from A to Z. There are no unexplained phenomena. Thakura is shut up in a madhouse now. In my opinion, he was already insane when he published his theory."

Larrabee was nodding, thoughtfully. "I wonder what makes you so certain of your theory?"

"What theory? I never deal in theories. I'm talking fact."

"Your theory that we have unveiled all the mystery of the universe; how do you know? Every now and then, of course, man lives through a century of such amazing progress that he concludes that nothing remains to be learned. But how can he ever be certain?"

"But we are certain! Most physicists are in agreement now that there hasn't been one single unexplained physical aberration in the past century!"

"Most physicists except Thakura, you mean?"

"But Thakura is insane! We understand all the physical phenomena of the universe."

"Except the Thakura Ripples?"

Jasperson slammed down his glass and stood up, his face red and puffy. "Steward! More ice water! I'm getting tired of those words, professor. Do you think for one minute I'd have risked my life to come on this trip if I'd thought there was the slightest danger?"

Alan looked up languidly. "You mean you wouldn't mind sending a crew and passengers into danger—as long as you could take care to be safe yourself?"

"Surely you're not afraid, Mr. Jasperson?" said Larrabee.

"No. What is there to be afraid of?" He gulped down his drink. "Nothing can wreck the Star Lord!"

When Dr. Alan Chase woke up next morning and glanced at his wrist watch, he realized that the breakfast hour was nearly over. Professor Larrabee had already left the cabin.

Alan was not hungry. It had been many months since he had really enjoyed an appetite for food, but he got up and began to dress, so that he could perform the duty of eating. But his clothes, he noticed, were beginning to fit a little more snugly. He fastened his belt at a new and previously unused notch, buttoned his jacket, and then performed the ritual he carried out every morning and every evening.

Touching a facet in the ornamentation of his wrist watch, he walked about, geigering the room. Radiation normal, somewhat less than earth's normal, in fact. The twenty-four Piles were well shielded, and if this continued, he should survive the journey in fair shape.

At the door of the dining room he paused, for the entrance was blocked by Steward Davis and the young couple he had noticed the day they left Y-port.

The tall young man with rumpled black hair was arguing, while the pretty girl