The formal beginnings of the search for extraterrestrial intelligence (SETI)
The search for life (intelligent or not) “out there” is one of the most intriguing and interesting aspects of modern science. However, it was not always held in such high regard. Prior to the 1960s virtually no astronomer who cared about his or her professional reputation seriously considered the idea of doing research in this area.
This changed in 1959. That year, a landmark paper published in Nature (arguably one of the two top scientific journals in the world) set the proverbial ball rolling with the following article:
“Searching for Interstellar Communication,” Nature, 184, 844 (1959) by Guiseppe Cocconi and Philip Morrison, two Cornell-associated physicists.
Credit: http://www.iaragroup.org/_OLD/seti/pdf_IARA/cocconi.pdf (this website contains the full paper)
This paper is widely recognized as the “official” start of the SETI effort. The paper concludes with what I think is what keeps fueling the interest of the search, and rightly so:
“The probability of success is difficult to estimate; but if we never search, the chance of success is zero”
The Cocconi and Morrison paper in a nutshell (or three):
The Cocconi and Morrison paper sparked the interest of quite a few scientists. It gave legitimacy to the SETI field and provided the framework to subsequent efforts like Project Ozma and the Green Bank Meeting, of Drake’s Equation fame.
Over the years, there had been quite a few false alarms, but probably the event that is the closest to the real deal happened in 1977. This event is widely known as the “Wow!” signal.
The most exciting moment in the history of this observatory, which earned it a place of honor in the lore of SETI, was the night of August 15, 1977. Big Ear’s observations were being recorded on a printout sheet: a long list of letters and numbers was continuously being printed out, one long list for every one of the scanned channels.
A list of characters appeared at the frequency of channel 2: “6EQUJ5“.
A Big Ear volunteer, Dr. Jerry Ehman, a professor at Franklin University in Columbus, was monitoring the readings that night. He circled the code for later reference and added a comment in the margins “Wow!”. He did not know that at that moment, he created the nickname of one of the most famous events in SETI history!
Anyway, 6EQUJ5”… Ok … So what?
To understand that, we can use the following comparison: In a crowded room, there will be a certain level of baseline noise, based on the conversations of the people inside. For anyone to be heard over the crowd, she would need to raise her voice louder than the average noise level, represented by:
If we take the average of all the high and low points, we can obtain a statistical value termed the standard deviation, which roughly accounts for the dispersion of the “noise”. An above average signal would look like this:
This concept is key to understand the Wow! signal code:
So, for 6EQUJ5:
If we look directly at a star, you are looking at its brightest part. If you start looking away a little bit, the apparent intensity of the light will diminish. You can assign numbers to these intensities. This is equivalent to what the Big Ear used to do…
There were several more details that lend credence to the possibility that this was a true extra terrestrial signal. You can find more about it in the references below. In the meantime…
So, what’s going on with Big Ear nowadays?
If you want to know more
http://www.bigear.org/wowmenu.htm (A great source of information)
http://www.bigear.org/Wow30th/wow30th.htm (A bit technical but rather thorough)
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