The Royal Society in London has been discussing the reasons why we haven't made contact with aliens from other planets.
We have been listening to radio waves from outer space and sending out our own for 50 years but still no contact. Why?
There are 3 reasonable explanations:
1. There are no aliens. There is no one out there to hear our signals, or see our TV images, or visit the Earth. We are alone. If that is the case, it suggests life on Earth is an experiment and that we really are the center of the universe, despite our position on the edge of the Milky Way galaxy. But why such a large universe for life on only one planet? What's the game?
2. Aliens are unable to contact us. They can't send signals that reach us, or that we understand. Perhaps they haven't sent a signal in our direction. There are technological hurdles that they haven't surmounted. They can't visit us in person, most likely because the distance is too great.
3. They refuse to contact us. Would advanced civilizations really want to contact us? Are we a desirable civilization? There are dangers. Whenever a more technologically advanced society on Earth interacted with a lesser society, the result was often tragic for the less developed people. Perhaps aliens fear us, and what we might do to them. It could be they are already aware that we have nothing that they want. We could be seen by aliens as galactic "trailer trash." Backward, ignorant, violent, and dangerous with nothing to offer them. They may well be "hiding" from us to delay any potential interaction.
If they were out there and amenable to communication, it seems we should have heard from them by now. There is some problem, without question, and the problem is one that we haven't really come to grips with yet. We don't want to believe the truth. We aren't ready for it.