Lasers V 
Just about every time you talk on the telephone, at least part of your message is transmitted by lasers -- beams of light that can carry enormous amounts of information across long distances.
In the future, those distances could get even longer. In fact, laser communication won't even be limited to Earth. Engineers are testing lasers as a way to stay in touch with probes in deep space. The first successful two-way test took place in 2007, with the Messenger spacecraft, which is on its way to the planet Mercury.
Laser beams can carry more information than radio waves because they're more tightly focused, they have a higher frequency, and their waves all march in step. In fact, a laser can transmit about 10 times more data than a radio system of the same power.
Some astronomers are betting that lasers can carry messages not just between planets, but between stars. They're using optical telescopes to scan for lasers beamed into space by other civilizations. They're hoping to "eavesdrop" on conversations between two civilizations -- or perhaps to find laser "beacons" that flash like interstellar lighthouses, alerting the rest of the galaxy to their presence.
Like radio searches for extraterrestrial intelligence, optical searches have come up empty -- so far. But the field is still in its infancy. Bigger telescopes and more extensive searches are needed to see if ET is using lasers to phone the rest of the galaxy.
Script by Damond Benningfield, Copyright 2010