Discussing the question "Do you consider yourself superior to people in the old days?," poster Matthew here is looking for the title and author of a short story from a scifi anthology with this plot:
A man invents a machine that can grab a man from the future and bring him back to the present. He uses the machine, and it works!
He speaks with the man, and sure enough, the society he comes from is far more advanced. We didn't destroy ourselves or go back to the Stone Age. All right! So far so good.
He asks how far Medicine has progressed. "Well, we've cured all disease" the man from the future explained. "When someone is ill, we just hold this little shiny cube up to them, and it heals them!"
"Tell me about this device. How is it made? What principles does it make use of?"
"I don't know. That's something only specialists understand. I just know that it's shiny, a bit warm, and 3x3x3 inches.
And the conversation goes on like this, in other areas of science and technology: computers, communication, food production, warfare, etc.
It was in one of those anthologies.
100 Great Science Fiction Short Short Stories
50 Short Science Fiction Tales
Golden Age Science Fiction Vol 1-5