Tuesday, March 16, 2010
Mad science: Can you hear me now?
The Guardian reports on an astronomer who claims that one of the unexpected consequences of switching to digital broadcast technology is that it makes the Earth harder to detect from space.
In the past, TV and radio programmes were broadcast from huge ground stations that transmitted signals at thousands of watts. These could be picked up relatively easily across the depths of space, astronomers calculated.
Now, most TV and radio programmes are transmitted from satellites that typically use only 75 watts and have aerials pointing toward Earth, rather than into space.
"For good measure, in America we have switched from analogue to digital broadcasting and you are going to do the same in Britain very soon," Drake added. "When you do that, your transmissions will become four times fainter because digital uses less power."
"Very soon we will become undetectable," he said. In short, in space no one will hear us at all.
Drake also notes that this goes both ways. Assuming that there's an advanced alien race out there, it is possible that they also let their communications systems develop for maximum efficiency, that is to say, max results for minimum energy expenditure. If they did, then they'd be as invisible to us as we are becoming to them.
What is true for humans would probably also be true for aliens, who may already have moved to much more efficient methods of TV and radio broadcasting. Trying to find ET from their favourite shows was going to be harder than we thought, Drake said.
Of course, this is only assuming that we want to be found. Perhaps a little cosmic camouflage is a good thing.