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Scientists seem to be on the hunt for mysterious signals. It seems that that there are quite a few of these signals to detect. As most of us know, we even have an organization named SETI dedicated to the hunting down of signals that might prove that there is other intelligent life in the universe. I have talked about SETI before, but for those that don't know what SETI is, it is the Search for Extraterrestrial Intelligence. When the government decided not to fund it anymore, it became private and now exists on donations and public help. By public help, I mean that many people with home computers have volunteered to let their computers analyze SETI data while the computers are not being used. The way that this is done, is that a SETI screen saver is supplied to those volunteers and when your computer is idle you will see it come on and crunch data packets looking for signals. If you are interested in participating, just go to http://setiathome.ssl.berkeley.edu/ and download the software and install it.

We don't hear much about SETI detecting strange or mysterious signals, but they do. The problem is that no signal they have detected has met the standards to call it extraterrestrial and intelligent, but that doesn't mean that some exciting signals weren't found. There are over three and a half million users of SETI software crunching away. There is a type of signal that is bell shaped, it is called Gaussian. This is the type of signal that SETI is concentrating on right now because it is believed that this is the type of signal that would be used to communicate with us by an intelligent race. The decision on which type of signal to analyze is nothing more than an educated guess however. The problem is that there are so many signals to be analyzed, it is like the old saw, so much work and so little time, but in this case it is, so much work with tons of more work being added every day and so little facilities for crunching. Thankfully the advancement in computers has helped quite a bit. As home computers become more powerful, their ability to crunch more and more data increases. This is rather obvious when you think about it. A few years ago a computer operating at 200 mhz. was considered very powerful, now the average computer may operate at ten times that speed and efficiency. But back to SETI signals. They have detected many signals that could be extraterrestrial, but they have been what is known as, one shot deals. In order for a signal to be recognized as an intelligent signal from extraterrestrials you have to be able to move the receiver away and reacquire the same signal again besides the other requirements. No promising signal has ever met all the requirements.

SETI scientists have found that they can get more Gaussian signals the faster the radio telescope slews (moves) through the sky. They also found that speed had a disadvantage, they don't get as much of the signal and this was a disturbing find. That meant that the signal didn't last for as long a time period and there wasn't as much of the signal to analyze. Here are the detailed requirements for an extraterrestrial intelligent signal:

First - the two signals must come from the same direction in the sky, to within 10 arc minutes. Location, of course, is the primary indication that the two signals are one and the same.

Second - the two signals must be detected at least 900 seconds apart. This is to ensure that the two are indeed separate detections, rather than a continuous one.

Third - the "barycentric" frequency of the two signals must be the same, within 125 Hertz.

What item three is talking about is something called the Doppler drift. Signals will drift in and out when received from space and this has to be compensated for. When it is corrected this is know as the detection frequency.

Because of the constant improvement in home computers, and the improvement in the SETI computers, more and more data is getting analyzed every year. It is possible that at some time in the future, they may be able to analyze all data without having to pick a certain type from the pool of data they have. I have crunched SETI data in the past and am about to do it again. It makes sense to me as I leave the computer on anyway and it is doing nothing. You see, I subscribe to the school of thought that you don't turn off the computer and this is easier on the hardware. This has served me well over the years, except for one time when somehow a power surge burned out by cpu and motherboard even though the computer was plugged into two power strips.

So what interesting signals has SETI gotten over the years? In 2003 SETI astronomers decided to examine a region of space that they had received mysterious signals from before. This didn't only happen once but twice. They received a signal and it was stronger than before. This was the third time that they detected this signal but it didn't meet the criteria listed above. This didn't mean that it wasn't interesting. The signal is now considered to be the best candidate discovered for extraterrestrial contact. When the signal is analyzed it drifts rapidly. If it is extraterrestrial that would mean that it comes from a rapidly. rotating planet.

Other candidates exist, but are not as promising as the one above, but even that could easily be something else. Before pulsars were discovered, the radio signals they gave out were thought to be from aliens., then there is also the possibility of fraud. Someone could just be playing a game with SETI. While this may sound absurd on the surface, just look at all those people that send out hoax letters and viruses. There seems to be no rhyme or reason for it, but it happens. Let's hope that as power increases in the next few years, we will finally be able to make contact.