The following is a compilation of some of my posts from another thread. Please read this if you are deciding wheter to join SETI or to Fold: SETI will never find anything. SETI operates on the assumption that another civ is transmitting open radio transmissions like we do now in the form of TV and Radio. But every day we stop these signals, XM Radio is gaining momentum, cable and sat TV will soon supplant broadcast and most of our communications are handled by direct beam sattelites. Logically, in about 50 years we will be transmitting next to nothing when it comes to wide band signals that can bleed into space. If an alien civilization follows a similar course of progress to us then they would only have radio transmissions that bleed into space for 100-200 years. A few centuries is a blink of the eye on the galactic scale and it is my observation that SETI is hopeless due to this narrow, limited method of detection. Odds are that there are no nearby alien cultures at the exact same point of development. Let's assume that there are 6 million advanced civilizations in the galaxy at any given time. Let's define an "advanced" civilization as a culture that has reached approx. 1800 AD technology level. Let's also assume that the average culture survives for around 4000 years past that point until their genetic stagnation finishes them off (assumiing they're brighter then humans, who will be gone in 200 years.) If they progress at a rate similar to our culture then they would transmit "wide band" EM signals for about 200 years or %5 of their lifespan.This means that there is 300000 civilizations that are on par with us and waste energy by bleeding it off into space. The Milky Way galaxy has anywhere from 200 billion to 400 billion stars. Let's say 300 billion stars for the sake of simplicity. We can then determine that the odds that SETI happens to be looking at one of the stars that happens to one of the 300000 cultures similar to our own is %.0000001. You are right about interference, if you assume that our odds of noticing the signal are bad it goes down to around %.0000000000001 that SETI will see anything when it looks at a star. I personally think that 6 million may be a bit too high and that many civilizations will last more then 4000 years, in which case the probability is even lower. In conclusion, it is nearly statiscally impossible that SETI will ever find anything. I personally believe that there are plenty of alien races in this galaxy alone. I just think that, like many NASA initiatives nowadays, SETI is doomed. The prospect of alien life has always intriuged me and as a result I have given quite a deal of thought to the SETI project and this is my conclusion.