If it's volcanoes or similar sources, though, we have to wonder where they actually are. Nothing that looks like an active volcano has been seen. And even if the activity were more subtle and less splashy -- the injection of lava below the surface somewhere, say -- it's hard to see how it would avoid giving off heat that TES on Mars Global Surveyor or Themis on Mars Odyssey would have picked up. A small and not very warm spot of geothermal energy might escape TES, which divides the surface up into fairly big parcels. But with a resolution of 100 metres in the infrared Themis should be able to pick up such things, and so far it hasn't, even though it's taken infrared data on large parts of the planet.

The other obvious possibility is life. On earth, almost all the methane in the atmosphere is produced by bacteria, specifically methanogenic archae. These are anaerobic organisms, which would suit them to Mars. Their metabolisms depend on making methane from carbon dioxide and hydrogen (the hydrogen itself sometimes a product of other bacterial life). These have long been seen as the most likely forms of life to be found on Mars.

People talk without thinking all of the time.

Literally.

If you doubt it, think about this: When you're talking, do you construct each sentence first in your mind, piecing the words together? Or do you simply talk, the words tumbling out in proper sequence and syntax?

For the most part, it's probably the latter. You don't think about each word before you speak it. "Your brain," says Koch, "takes care of that quite well without any conscious effort on your part."

Speaking is, in profound ways, a "nonconscious" behavior. It is a mental operation not directly associated with conscious feelings, sensations or memories. It just sort of happens, seemingly, on its own.

The same is true about much of life. Surprisingly big chunks of it, Koch writes in his new book, "The Quest for Consciousness," happen without us being consciously aware they are happening.

"We all do things every day, virtually every minute, that do not involve conscious thought, from tying our shoes, to driving to work or working out, to cooking dinner," said Koch. "These actions are essentially routine, automatic. You do them without thinking and often have no direct memory of them afterward."

When Dr. Newdow described "under God" as a divisive addition to the pledge, Chief Justice William H. Rehnquist asked him what the vote in Congress had been 50 years ago when the phrase was inserted.

The vote was unanimous, Dr. Newdow said.

"Well, that doesn't sound divisive," the chief justice observed.

Dr. Newdow shot back, "That's only because no atheist can get elected to public office."

The courtroom audience broke into applause, an exceedingly rare event that left the chief justice temporarily nonplussed. He appeared to collect himself for a moment, and then sternly warned the audience that the courtroom would be cleared "if there's any more clapping."

Recent news stories have covered the announcement of ChatNannies, conversational robots designed to locate and lure pedophiles in Internet chat rooms. Uncritical articles were recently published by New Scientist, BBC News, News.com, the skeptically-minded The Register, and many other news outlets.

Cameron Marlow managed to secure an exclusive interview with one of the "Nanniebots," where he posted a complete transcript and some brief analysis. To anyone who knows anything about chatterbots and the history of artificial intelligence, the transcript represents either a revolutionary leap in technology or it's clearly a human behind the keyboard.