male viewpoint. You're wiser than I had realized. But
why me?"

He forced himself to meet her eyes. "You appear the most sensible of the
women awake."

"Really!" She laughed. "I appreciate the compliment, but must you
deliver it in that parade-ground voice, and glare at me to boot? Relax,
captain." She cocked her head, studying him. Then: "Several of the girls
don't get this business of the critical point. I tried to explain, but I
was only an R.N. at home, and I'm afraid I muddled it rather. Could you
put it in words of one and a half syllables?"

"Do you mean the equal-time point?"

"The Point of No Return, some of them call it."

"Nonsense! It's only--Well, look at it this way. We accelerated from Sol
at one gravity. We dare not apply more acceleration, even though we
could, because so many articles aboard have been lightly built to save
mass--the coldvats, for example. They'd collapse under their own weight,
and the persons within would die, if we went as much as one-point-five
gee. Very well. It took us about one hundred eighty days to reach
maximum velocity. In the course of that period, we covered not quite
one-and-a-half light-months. We will now go free for almost forty years.
At the end of that time, we'll decelerate at one gee for some one
hundred eighty days, covering an additional light-month and a half, and
enter the e Eridani System with low relative speed. Our star-to-star
orbit was plotted with care, but of course the errors add up to many
Astronomical Units; furthermore, we have to maneuver, put our ships in
orbit about Rustum, send ferry craft back and forth. So we carry a
reaction-mass reserve which allows us a total velocity change of about
one thousand kilometers per second after journey's end.

"Now imagine we had changed our minds immediately after reaching full
speed. We'd still have to decelerate in order to return. So we'd be
almost a quarter light-year from Sol, a year after departure, before
achieving relative rest. Then, to come back three light-months at one
thousand K.P.S. takes roughly seventy-two years. But the whole round
trip as originally scheduled, with a one-year layover at Rustum, runs
just about eighty-three years!

"Obviously there's some point in time beyond which we can actually get
home quicker by staying with the original plan. This date lies after
eight months of free fall, or not quite fourteen months from departure.
We're only a couple of months from the critical