"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.