As early as the 1850s Michael Faraday tested ice cubes that were sticking together and concluded that ice surfaces must just inherently consist of a thin film of water, at whatever temperature. So mark c). Even ice at minus 200 F has a "quasi-fluid layer" that makes the stuff slippery, says Exploratorium.edu. This may help explain the "fast ice" and "slow ice" of hockey: As the ice gets warmed, the number of slippery layers increases, until skaters need to "slosh" through so many layers that the friction slows them down.

On the other hand, these extra layers can help "soften" the landing of a figure skater, whose ice should be warmer than for hockey players. By the time ice gets down to minus 250 F (minus 157 C), the slippery layer is just a single molecule thick! Nanohockey, anyone?

Q: Who sent the world's first e-mail?

A: If the question means "who sent the first message over a network from one computer to another computer?," then Len Kleinrock — UCLA professor and one of the inventors of Packet Switching — lays claim to this, though it is not known for sure, says computer scientist Alan Kay of UCLA, MIT and Kyoto University.

This was done on the old ARPAnet, which became the Internet and which first started up in September 1969. However, sending messages to others, including instant messaging and chat, appeared much earlier on the first time-sharing systems, says Kay. These were big mainframe computers that could handle 100 or more users at a time communicating with the mainframe via typewriter terminals.

One of the earliest was CTSS at MIT, circa 1963. Another was Project Genie at Berkeley. Both had e-mail, IM, and chat. So why did it take so long for e-mail to catch on? "Quite a few people have to believe something is normal before it becomes normal — a sort of 'voting' situation. But once the threshold is reached, then everyone demands to do whatever it is."

Gotta go now to check our e-mail.

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Send STRANGE questions to brothers Bill and Rich at strangetrue@compuserve.com, coauthors of "Can a Guy Get Pregnant? Scientific Answers to Everyday (and Not-So- Everyday) Questions," from Pi Press.