 Which item doesn't get mentioned while they're in the year 2150?
There is one fact no sane man can quarrel with ... You will, you know, so why quibble about it? Yes, it'll be pretty obvious it must be a time machine. 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 are completely outside of time and space, as best you can guess how things are. "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. I figured out once that such a universe would need some seven or eight time and space dimensions. Anyhow, you sit there, watching nothing all around you, and no time, apparently, though there is a time effect back in the luggage space. That means you either carry a small time field with you, or you are catching a small increment of time from the main field. You suddenly realize that everything in the machine is wide open, yet you haven't seen any effects of air loss. Out there is neither time nor space, apparently. He told me, just as I'm telling you, that it's an interstellar civilization." It gives out a coughing noise and the basement openings begin to click by us. There's no feeling of acceleration—some kind of false gravity they use in the future.
 flying vehicles
 flying vehicles  diamond makers  an elevator that you can't feel move  a modified English language