This is most likely Isaac Asimov's best story. It appeared in the November 1956 issue of Science Fiction Quarterly and Asimov said [when he read his own stories: HERE] that "it is just about my favorite story of all the stories I have written."
It is certainly a superb story on the nature of entropy and the ultimate question: Can entropy be reversed? The twist which provides the answer comes in the final lines of the story and is stunning. There is little more that I can say without completely giving the story away. If you like Asimov, if you like good science fiction, if you like a blazing good story...just read it. Or, as I did, listen to it. I listened to Isaac Asimov read it. But my preferred version is the reading by Leonard Nimoy (below). ★★★★★