One of the 125 questions.
In 1935, Einstein came up with a scenario that still defies common sense. In his thought experiment, two particles fly away from each other and wind up at opposite ends of the galaxy. But the two particles happen to be 'entangled'--linked in a quantum-mechanical sense--so that one particle instantly 'feels' what happens to its twin. Measure one, and the other is instantly transformed by that measurement as well; it's as if the twins mystically communicate, instantly, over vast regions of space. This 'nonlocality' is a mathematical consequence of quantum theory and has been measured in the lab. The spooky action apparently ignores distance and the flow of time; in theory, particles can be entangled after their entanglement has already been measured.Nonlocality, if it were demonstrated to actually exist and to imply a faster than light "connection", ought to make one wonder if we're "living in a simulation".
Update 6/12/07: Ahh, those were innocent days. I later engaged in a "catchup with physics" project, to discover that nonlocality died about ten to twenty years ago, though there may have been a prolonged period of denial.