"As you know, professor," said the earnest young man, "an Embry-dissipative microsingularity striking the earth would be drawn irresistably to its core, where it would cause a cataclysmic gravitational distortion, drawing all matter down into it until the earth collapsed in on itself like a rotten grapefruit."

"What the hell are you talking about?" I said. "I study acoustics."

"Professor," he said, leaning in, whispering urgently, the mothy smell of his ill-fitting suit coat forcing me to fight a sneeze. "Please don't ask me how I know about your top-secret government work, but understand that I have information of the greatest importance for you. A microsingularity is bearing down on Earth at this very moment, and the vector and velocity information I have for you--"

Top-secret government work? This fellow was a nut case!

"Just a minute," I said, picking up the phone. I dialed security. "Hi, I have a special package for you to pick up on the second floor," I said.

"Dr. Womack, is that you?" said Rob the security guard over the phone. "You're saying there's some kind of problem? What's wrong?"

"Absolutely, and you have a nice day, too," I said, smiling and nodding at the young man. I hung up, hoping Rob had gotten the idea.

The young man held out a thumb drive. "These are the coordinates--" he broke off as he heard the noise of feet pounding on the stairs down the hall. A moment later, Rob and the red-haired bodybuilder type, what's-his-name, burst in and grabbed the young man by the arms.

"Stop!" he cried. "You're making a terrible mistake! Please, professor, please!"

They dragged him away.

About ten minutes later, Dr. Fennelgrüb walked in with a latte and a chocolate pastry.

"You're in my office again, Womack!" he bellowed, pastry crumbs flying from his lips. "So help me God, the next time you blunder in here, I'll kick your ass!"

I looked around, and of course he was right: wrong office again. My mind had been on the impact of air currents on sound conductance in low-heat environments, and I just hadn't noticed. I meekly scraped together my papers and left. On the way out, I wondered if Fennelgrüb needed to be told the young man's news, but then I was struck with an idea about heat differentials that completely put the matter out of my mind.