I was reminded of it by Pascal blogging about 2012 (I first read about this a decade ago. I can't believe how famous it's becoming. It's the new millennium bug. But maybe this one will work), and mentioning another classic, Clarke's The Nine Billion Names of God. Also warmly recommended. (Spoiler warning, Pascal's blog post reveals the ending of the story.)
I love big-perspective stories, and stories which make you think.