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Interesting speculation, but I agree with Fermi and BillyBob. If Sagan was even close to correct, we'd have seen them by now. A jupiter sized planet is not particularly hospitable to life as far as we can tell so far. I am all for exploring space, don't get me wrong, but I just don't think we will find any life.

One interesting logical flaw in the "non-interference" theory (the one that says the aliens have found us but have left us alone for awhile) is that it is basically saying the absence of evidence is evidence. The fact that we have not seen aliens means they are there (or might be there) but are not showing themselves. This is extremely problematic from an epistemological perspective. That is, we can never know if it is true or not as long as the aliens decide to refrain from contact. It's basically useless and an intellectual dead end.

Finally, exploring space is fine for its own sake as far as I am concerned. But, when the goofy people start their fantasy stuff it really creeps me out personally. They go overboard beyond the realm of facts and science into this weirdo land that just does not make sense. What business case or scientific curiosity case could ever be made for these Von Neumann probes? Where would anyone ever get the capital to develop these? Who would ever invest such enormous sums? Look how absurd this is when compared to what little has been accomplished with the space station and how much has been spent on it.

I think separating fantasy (not dreams) from reality is key to making any progress. Otherwise we are simply fooling ourselves and will never get anywhere in space. It will be costly. People will die. And we should go anyway because it's there to be explored. Beyond that, we will see what we will see.

I think that when we can resolve earth-sized planets from space-based telescopes, we will be able to tell from spectrographs which, if any, have the characteristics of life.

If we consider how brief has been our rise to civilization and how briefly we are likely to linger at this particular level of technology, I think it unlikely we will find anyone like ourselves. What exactly we might find, I have no idea.

You mean you have no evidence. If they didn't show up for you does that mean that no-one else has seen them?
I've seen ships flying around the desert and there is no way we made them. No wings, no noise, moving too slow for aerodynamics of lift and so on.
Perhaps they are so much more advanced than us that we would not recognize them.
To think that we are the absolute pinnacle of intelligence in the universe is depressing.
Perhaps they have moved way beyond conflict and are able to harmonize with us in such a way as to be invisible to us.
We seem to recognize by conflict most of the time.
We think they must be very different from us but what if they are not.

We have seen them by now.

We've shot them, imprisoned them, bred with them at their manipulation; made contracts with them which they've broken; been shot by them; shot their craft down; had them shoot our planes down; had them remove/destroy virtually all atomic reactors or atomic weapons we've sent to space . . . etc. etc.