SETI

Extra Terrestrial Intelligence Is there intelligent life on other planets? If so, –Can we find them? –Can we try to communicate? SETI is the Search for Extra Terrestrial Intelligence

Evolution of Intelligence If a planet has life, will intelligence evolve? –Within the last 2 million years on Earth –Less than 1/1000 the time since life appeared How probable is the development of technology? –Radio communications for just 100 years –Less than 1/10,000 the time since humans appeared How long will an intelligence survive?

Drake Equation In 1960 Frank Drake created a way to estimate the number of planets with civilizations capable of interstellar communication. –The Drake equation –Rate in years  R * = 1; rate of stars forming  f p = 1; fraction with planets  n e = 0.1; earth-like planets  f l = 1; fraction with life  f i = 1; intelligence fraction  f c = 1; communicating aliens  L = 100; lifetime of civilization  Total = 10 in the galaxy

Communicating with ET Sending a spaceship is too slow (25,000 mph = 11 km/s). –300,000 years to reach the nearest star Radio communication is much faster (300,000 km/s). –4 years to the nearest star –Earth radio to stars within 100 light years A planet 60 ly away could be watching “I Love Lucy”.

Searching for Signals Civilizations may also be sending information. Radio waves (including TV) are easy to detect. Radio telescopes scan the sky for radio objects. Searches analyze data in parallel with other experiments.

Home Data must be scanned for signals. –Weak signals, lots of noise –Needs lots of computer time uses volunteer So far, the fluctuations seem to be random.