Two Cornell scientists, Phillip Morrison and Giuseppe Cocconi, speculated about what a signal from an alien civilization might look like. They reasoned that since a hydrogen atom (the most common one in the universe) resonated at 1420 megahertz (MKZ), that the signal would come in at this frequency and would be loud to get our attention. A scale to measure loudness was devised that started with numbers and then moved to letters.
On August 18, 1977 just such a signal appeared from the constellation Sagittarius just to the northwest of the globular cluster M55. SETI scientists unfortunately could find no star or planet or anything at all where the signal came from. The signal lasted for just a couple of minutes and then stopped. No one was ever able to pick up the signal again. The incredible thing is that the signal came in almost exactly as predicted at 1420 MHZ and had a rapidly rising volume that went all the way to U on the log scale used to measure the strength of the sound. When Jerry Ehman heard the signal and saw the measurements on the printout, he simply wrote “WOW” on the paper, convinced he had made the discovery of a lifetime. The scientific method however requires repeatability and that signal could never be found again.
Over the years, almost all other possible explanations have been dismissed. The WOW signal still remains our single best evidence that life is out there.. It was not only a WOW moment it was a deep mystery with no apparent answer. Here is the wow printout.
ET, why do you have to be so meant? My guess is that it was a signal from a rapidly moving alien spacecraft. A temporary tease to keep the SETI project well funded. OK that’s not really my guess. Actually I believe that all civilizations move rapidly through a technology phase where they create their own successors (AI beings.) Such a civilization might quickly go virtual and lose interest in the actual physical universe. That might well explain why SETI hasn’t found anything yet … the WOW signal notwithstanding.