"You see, since your mathematical friends derived their identical formulas for gravity and electromagnetism, my job was pretty easy. As you know, a falling body follows the line of least resistance in a field of distortion of space caused by mass. I bend space into another such field by electromagnetic means, and the _Comet_ flies down the track. Working the mercury disintegrators at full power, I can get an acceleration of two hundred miles per second, which will build up the speed at the midpoint of my trip to almost four thousand times that of light. Then I'll have to start slowing down, but at the average speed the journey will take only six months or so." * * * * * "But can anyone stand that acceleration?" Kelvar asked. "I've had it on and felt nothing. With a rocket exhaust shoving the ship, it couldn't be done, but my gravitational field attracts the occupant of the _Comet_ just as much as the vessel itself." "You're sure," I interrupted, "that you have enough power to keep up the acceleration?" "Easily. There's a two-thirds margin of safety." "And you haven't considered that it may get harder to push? You know the increase of mass with velocity. You can't take one-half of the relativity theory without the other. And they've actually measured the increase of weight in an electron." "The electron never knew it; it's all a matter of reference points. I can't follow the math, but I know that from the electron's standards it stayed exactly the same weight. Anything else is nonsense." "Well, there may be a flaw in the reasoning, but as they've worked it out, nothing can go faster than light. As you approach that velocity, the mass keeps increasing, and with it the amount of energy required for a new increase in speed. At the speed of light, the mass would be infinite, and hence no finite energy could get you any further." "Maybe so. It won't take long to find out." A few of the brightest stars had begun to appear. We could just see the parallelogram of Orion, with red Betelguese at one corner, and across from it Rigel, scintillant like a blue diamond. "See," Garth said, pointing at it. "Three months from now, that's where I'll be. The first man who dared to sail among the stars." "Only because you don't let anyone else share the glory and the danger." "Why should I? But you wouldn't go, anyway." "Will you let me?" I had him there. "On your head be it. The _Comet_ could hold three or four in a pinch, and I have plenty of provisions. If you really want to take the chance--" "It won't be the first we've taken together." "All right. We'll start in ten minutes." He went inside the ship. * * * * * "Don't go," Kelvar whispered, coming into the _Comet's_ shadow. "Tell him anything, but don't go." "I've got to. I can't go back on my word. He'd think I was afraid." "Haven't you a right to be?" "Garth is my friend and I'm going with him."