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Ok, here's my take:
Regular TV signals probably aren't reaching far enough out into space that they would be intercepted by anything that wasn't deliberately looking very intently at our particular planet.
However, While TV signals are designed to remain earthbound, sattelite uplinks are not, and they are very directed, high power, and aimed 'up.' You also have the cross talk between sattelites which both originate in space and are directed at another body in space. There is a lot of spillover that an intelligent race who bothered with such things could pick up. If they were within range.
I don't think we have really started emitting interceptable signals until the dawn of sattelite communication.
Of course, those signals have to actually reach out and get intercepted by little green men light years away. I don't think it is plausible to suggest that they are in our solar system. Why would they travel so far to hide out? The only thing our solar system has that other star systems don't is a planet full of people, squirrels, etc. Earth is the only possible attraction. If they were already here I think we would know.
I don't think interstellar space is where aliens would be found either: It is devoid of resources and not very hospitable. Why would they hang out there? In order for them to be in open space, they would have to be in the middle of a LOOOOONG journey, and they would probably not change a decades-long course for an unknown planet that is still many light-years away.
So, our signals would have to reach an occupied system that has aliens whose evolutionary development is at least comprable to our own (they have to be listening, anyways). But we are listening also, and if there is a highly advanced form of life out there that bothers to listen to radio waves, it is probably because they also use radio waves, and we should have been able to hear that. Especially since they would have to be within a couple light-decades in order for our signals to reach them.
Furthermore, in order for them to respond to our signal and come scare nutjobs with their UFO's, they would have to be no more than half the distance away from us that our radio waves have traveled (assuming they can travel at the speed of light).
So basically, they would have to be within 15 light-years of us, and capable of travelling at light-speed, and willing to do-so at the first hint of radio-signals from Earth, and they would not be creating their own radio emissions....or we would have noticed.
There aren't many stars within 15 light-years, and even less with habitable planets. What are the odds? Yep. Pretty much zero.
Furthermore, if a civilization is advanced and spans many star-systems, etc. then we would probably have been able to see cyclic-variations in all the little sub-cultures left behind. Think about it: as they spread out across the galaxy, each planet would be essentially isolated from the others by sheer distance...which leaves plenty of room for social upheaval, wars, etc. It is a process that would require many thousands of years, and endless opportunity for radio emissions, nuclear explosions, etc. Yet we look into space and see no indication of this at all.
I am sure life exists elsewhere in the universe, the universe is too big a place for it not to.
However, it is also too big for us to 'bump' into aliens.
By the time an 'alien' race is bathed by our radio-signals and is able to stop by for a chat, we will probably be long gone.
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"Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery." - Winston Churchill
"All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find that it was vanity: but the dreamers of the day are dangerous men, for they may act out their dream with open eyes, to make it possible." Seven Pillars of Wisdom, T.E. Lawrence
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