How Would ET Phone Home?

Because light travels at a fixed speed it takes a long time for a signal to reach us. The basic problem with communicating with aliens is that the nearest stars are 3-10 light years away. If you said hello it would take three years for that message to get to the alien star and three years to come back. The other problem of course is aliens will not necessarily have communication of the same kind as us. What we would have to do is send signals that are numbers like 2, 4, 6, 8. That's the content of the communication. The second part is how do we communicate? Scientifically I think there are two really approaches that are currently available to us on Earth. One is the standard technique which is to use radio signals and we listen with the biggest telescopes on the Earth. The Arecebo telescope, which is a 300m diameter has been used. Radio astronomers are currently working on the design of a radio telescope which will be ten times larger. Those telescopes will be mainly used to listen for extra terrestrial life. An alternative approach is to use lasers. Lasers have the advantage that they're highly directional. You could point high-powered laser at a specific star. One thing about technology is that we're in a period where technology's improving all the time. If you want to communicate with aliens and you think it's going to take many years to start this conversation it is possibly better to wait maybe 10, 20, 30 years until our technology improves significantly.