Atmosphæra Incognita

by Neal Stephenson

“A couple of decades ago,” she said, “some of our orbiting gamma ray observatories began picking up incredibly powerful bursts. Long story short, it became obvious that these were coming not down from deep space but up from below—from the earth. So powerful that they maxed out the sensors, so we couldn’t even tell how massive they actually were. Turned out they were coming from thunderclouds. The conditions in those storm towers down there are impossibly strange. Free electrons get accelerated upward and get kicked up into a hyperenergetic state, massively relativistic, and at some point they bang into atoms in the tops of the storm towers with such energy that they produce gamma rays which in turn produce positrons—antimatter. The positrons have opposite charges, so they get accelerated downward. The cycle repeats, up and down, and at some point you get a burst of gamma rays that is seriously dangerous—you could get a lifetime’s worth of hard radiation exposure in a flash.” She paused for a moment, then stared directly at me with a crazy half smile. “The earth,” she said, “is an alien world.”