Can other civilizations detect us?
Another of these great unknowns is whether aliens are even bothering to listen to radio signals. Sure, any advanced civilization would be able to pick up radio waves. But just because they are technologically advanced doesn't mean they even use them. Perhaps the society used to use radio signals, but they have evolved to a state where they use other forms of communication.
A book I had once described it as this, and I'm paraphrasing: Perhaps the use of radio signals as forms of communication among intelligent beings is as quaint as fire signals used between neighboring tribes in the jungle.
Maybe these civilizations see our means of communication as a symbol of being "non-evolved" or not worthy of being associated with.
I think the far more likely scenario is any civilization that exists in our part of the galaxy does not have the means to communicate with us -- other than coming down to Earth and meeting us in person.
I think we are going to have to expand our technology and do some hard brainstorming to consider how more advanced civilizations may be communicating with each other in the universe.
Did you know that aliens -- if they exist -- may know we're here?
Ever since the advent of radio transmissions, signals emanating from Earth have been heading out into space at the speed of light.
In December of 1900, Reginald Fessenden transmitted a brief radio wave between two stations a mile apart on Cobb Island in Maryland.
One hundred and sixteen years later, that signal has reached 116 light years into space. Following them, as humanity has technologically evolved, are much more powerful signals. Television signals are now out in space, too. Does that mean aliens could be watching one of your old favorite TV shows?
Well, maybe. But probably not.
Although technically radio signals far from Earth would be detectable, they would be very difficult to distinguish from other "noises" and signals in the cosmos.
The problem here is signal degradation. As radio signals travel farther into space, they become significantly less powerful. Could aliens floating around in the Solar System pick up our radio signals? Sure. What about extraterrestrials living around the closest star to Earth, Proxima Centauri? Maybe.
But once we get into multiples of 10 light years away, signals theoretically would become very difficult to pick up.
One question worth thinking about is, if there was an alien civilization 100 light years away, and they somehow could detect our radio signals, would they somehow be able to tell that they were coming from us? From a technological society?
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