Here is a real brain teaser that has always baffled me. Years ago, back in the bad old pre-cable days of cheesy TV antennas, I was watching something of interest and, since I was working around the house, I had both of our TV sets on the same channel for optimum viewing from any location. I happened to be in a position to see both sets when some kind of interference caused a loss of the signal intermittently. The picture to turn to snow, then back to the picture, back to snow, and back to a picture. This repeated for a total of about four or five cycles. The on and off times appeared to be about the same - about 1 second. Now here is the really perplexing part: The two TV sets were oscillating in unison but 180 degrees out of phase. They were on separate antennas and separated by about 30 feet. How in the heck can this happen? At the time I was immediately and completely baffled and have remained so since. Am I missing something obvious? The only guess I have ever managed is that the polarity of the power to the two sets was opposite and that this anomoly was due to some kind of power fluctuation. These sets could have predated the polarized power 110vac plugs used today.