 Why is there no feeling of acceleration in the elevator in the future?
[Transcriber's Note: This etext was produced from Galaxy Science Fiction February 1951. There is one fact no sane man can quarrel with ... But some men aren't sane; thus it isn't always so! I'm not your father's ghost, even if I do look a bit like him. You will, you know, so why quibble about it? At least, you always have ... or do ... or will. And don't look at the machine out there too long—until you get used to it, you'll find it's hard on the eyes, trying to follow where the vanes go. You'll get used to it, of course, but it will take about thirty years. And naturally, since we have the same tastes, you can make the same for me as you're having. It's a real wrench when a man meets himself for the first time. Some kind of telepathy seems to work between two of the same people. So let's begin when you get up in half an hour and come out with me. Yes, it'll be pretty obvious it must be a time machine. You've seen it, just a small little cage with two seats, a luggage compartment, and a few buttons on a dash. You'll be puzzling over what I'll tell you, and you'll be getting used to the idea that you are the man who makes atomic power practical. You won't exactly believe it, but you'll want to go along. I snap on a green button, and everything seems to cut off around us. You can see a sort of foggy nothing surrounding the cockpit; it is probably the field that prevents passage through time from affecting us. You start to say something, but by then I'm pressing a black button, and everything outside will disappear. There is exactly nothing there—in fact, there is no there . You are completely outside of time and space, as best you can guess how things are. You can't feel any motion, of course. Doesn't hurt, and when you pull your arm back, you're still sound and uninjured. Then it comes to you slowly that you're actually traveling in time. Then you feel silly, because you'll remember that I said you'd ask that. "Maybe it's no dimension—or it might be the fifth; if you're going to skip over the so-called fourth without traveling along it, you'd need a fifth.
 The false gravity used in the interstellar civilization.
 The force is too fast to be felt.  The elevator doesn't actually move, only the scenery does.  It's moving slower in opposition to the gravity.  The false gravity used in the interstellar civilization.