Facebook users were amused Thursday when some were invited to celebrate "46 years of friendship on Facebook" with one or more of their online friends ... even though some of the users involved hadn't yet been born 46 years ago, and of course, Facebook wasn't even around until 2004. Facebook blamed a software bug and didn't elaborate, the AP reports, but computer experts speculate that a quirk in Unix, an operating system used in big data centers where companies like Facebook store information, is behind the glitch.
Unix time, or Epoch time, counts the time since Jan. 1, 1970. Basically, the internal calendar on some computers starts at midnight, Greenwich Mean Time, Jan. 1, 1970, but one developer points out that can sometimes turn into Dec. 31, 1969, due to time zone adjustments. And an error might have caused the clock on Facebook's friendship-duration feature to have been restarted somehow. Gizmodo has a longer, "nerdy" explanation. (Read more Facebook stories.)