David Morrison has a big job.
"I volunteered about 10 years ago to answer the questions the public sends in," he explained.
Some are about the most pivotal scientific questions of our time.
"These are questions about astronomy and planets and life in the universe," he said. "And that went along fine until about four years ago when suddenly I started getting these questions about the end of the world."
Doomsday was forecast to happen last year by Christian radio host Harold Camping. Now, some say the ancient Mayan calendar predicts the end of days on Dec. 21, 2012.
Morrison's inbox is overflowing.
"One touching letter was simply, 'My best friend is my little dog, please tell me when I should put her to sleep so she won't suffer in the apocalypse,'" Morrison said. "I'm disturbed by letters from kids who are afraid. I think that is the worst part of this hoax. And it is a hoax."
A hoax, he says, with tens of millions of views on YouTube: one predicts a planet crashing into the earth.
Morrison has posted his own YouTube videos, but the letters keep coming.
"I have received letters from young people who say they are contemplating suicide; I've received a few from mothers who say they're planning to kill their children and themselves," he said.
He answers all of them -- but it takes a toll.
And when he wakes up on Dec. 22, Morrison says he'll hand over the job of answering questions to somebody else.
"I've become sort of obsessed with doomsday 2012, and I'd be glad to drop it," he said.
Morrison is a scientist, not a historian, but he's done some research and says the same ancient Mayans who created that calendar also prophesized some events to happen 300-500 years from now, meaning even they didn't think the world was coming to an end.