Short story: temporal paradox caused by experiment ends world

Question

This might be one of Fredric Brown's short-short stories, but I've tried and could not find a reasonably quick way to look up summaries of all his stories.

A group of scientists in a lab decide to experiment with backward (in time) causation. The experiment goes disastrously wrong and the world ends.

The details, as far as I remember them: A brick suddenly materializes on a lab bench. This is just as expected. An hour passes. At this point in time the scientists are supposed to press the button that will send the brick back in time. Dr. X says, "Hey, let's see what happens if we don't do it." Instantly, Dr. X, his colleagues, the lab, the city, the planet, and the entire universe vanish. Only the brick remains.

Answer 1

This is Fredric Brown's "Experiment", a one-page short-short. Project Gutenberg etext here.

"See? Five minutes before I shall place it there, it is there!"

His other colleague frowned at the cube. "But," he said, "what if, now that it has already appeared five minutes before you place it there, you should change your mind about doing so and not place it there at three o'clock? Wouldn't there be a paradox of some sort involved?

An interesting idea," Professor Johnson said. "I had not thought of it, and it will be interesting to try. Very well, I shall not . . ."

There was no paradox at all. The cube remained.

But the entire rest of the Universe, professors and all, vanished.