Tau Zero

by Poul Anderson

The device was not for amusement or comfort; it was a valuable navigational aid.

Clearly, though, the computer needed data on where the ship really was and how fast she was travelling

It did not quite require him to revolve in a logical circle—find

Distant galaxies were his primary beacons; statistical analysis of observations made on closer individual stars gave him further data; he used the mathematics of successive approximations.

This made him a collaborator of Captain Telander,

who computed and ordered the needful c...

the Lunar maser beam could still reach her with inquiries, entertainment, news,

Her unmanned precursor had had no problem with sending information.

seldom above fifty kilometers per second. And they do not zigzag, however slightly.

they must hurry. Aberration and Doppler shift affect

when travel time between maser projector and ship stretched into months, the beam was sure to lose her.

He strengthened the signals which he punched Solward, hoping they would give clues to his

But the quality of reception was always poorer, the interval of it shorter, the time till the next longer, as Leonora Christine entered the Big Deep. Ingrid

obviously thrown on this minute. “May I come in?” she requested.

had been screened off from the part currently occupied by Biosystems Chief Pereira.

An unmade bed filled most of it. A vodka bottle stood on the dresser.

Lindgren sat down on the edge of the bed. “No, thanks,” she replied. “I’m on duty.”

“And I’m supposed to be. Yes,” Fedoroff loomed over her, slumping.

He gave her a glance and a more nearly genuine smile.

“I doubt if you do, really.” Fedoroff turned to confront

Fedoroff was unmoving for so long that she started to rise and go.

They ought to’ve cracked your riddles before we come to a stop.”

At a minimum, these people would spend another half decade in the Beta Virginis System,

Eridanian

He fell silent, fiddled with a titration setup, until ship-drive and ventilator breath, sharp chemical odors, bright colors on the reagent and dye shelves, shoved forward into consciousness. At length he cleared his throat. “Uh, Emma.”

diffidence.

“Okay, if you don’t want a cocktail, what about a cup of coffee?

started,

there is an interdependence of space, time, matter, and energy. The tau factor enters

the equations. If v is the (uniform) velocity of a spaceship, and c the velocity of light, then tau equals The closer that v comes to c, the closer tau comes to zero.

Furthermore, if the “stationary” observer could compare the ship’s clocks with his own,

The interlude between two events (such as the birth and death of a man) measured aboard the ship where they take place,

Now measurements made on shipboard are every bit as valid as those made elsewhere.

If you ran tau down to one one-hundredth and went into free fall, you would cross

of course, you could never regain the century that had passed at home, during which your friends grew old and died.)

Others played games, chattered, offered drinks around, flirted, got boisterous.

Iwamoto Tetsuo, Hussein Sadek, Yeshu ben-Zvi, Mohandas Chidambaran, Phra Takh, or Kato M’Botu seemed to belong with it as much as Olga Sobieski or Johann Freiwald.

He hugged Jimenes to him. She snuggled. “Have you called his cabin?” “Naturally. No response. Still, maybe—” Reymont turned. “I’ll try there. Later I’ll come back for that schnapps,” he added, already leaving.