It's just that they are so far away. there is so little chance of crossing paths

I believe there are other civilizations out there, too, both less and more advanced than the human race. I think we will "discover" them when we have advanced technologically and socially to the point where mankind can handle the discovery.

Mathematically, yes, IF we assume that all biospheres are equally likely to evolve one or more sentient species and that most of these are on some sort of linear march to technological civilization and interstellar travel.

But those are pretty big assumptions.

I think there are probably "brick walls" that present insurmountable obstacles to natural selection, such that for example unicellular life is far more likely to appear than multicellular, plants more than animals, and so forth, and finally, that there are probably at least a hundred ways for sentient life to destroy itself before it has both the advanced technology AND the maturity / wisdom to use it. It is entirely possible that only a minority of species make it past the discovery of certain technologies to go on and flourish enough to undertake the tremendous costs of reaching out to the stars. It can be plausibly argued that at the rate we're going, we're not one of those ourselves.

While it's likely that we're not alone even among sentient species, we also have to explain why, if that's so ... and especially if we're in a Star Trek style universe just teeming with such beings ... why we haven't seen the slightest evidence of any of them.

If I had to hazard a guess at what we'll find when we eventually explore the Local Group, I think we'll find an average of less than one planet per solar system with ANY kind of life and most of what we're going to find is relatively simple organisms. I think it may be a very long time before those who want to think we're some one-off god project are disabused of that notion by the discovery of even primate-level proto-sentience on other worlds.

Ha, I love that user name.

I agree with the part about the math, but knowing about extraterrestrial life? For me, I'd want to know if we discovered it, but not if it came here.

I'm pretty sure that aliens that intelligent and advanced would see humans as ignorant, violent, and potentially dangerous. With no frame of reference for or insight into how they would think, I am concerned they'd think their best course of active would be to eliminate Earth.

I get this argument, but until there is direct observational evidence for life elsewhere in the universe I will say we are the only intelligent life in the Universe.

Disbelief in a God/gods due to a lack of objective, testable evidence is one reason we're on this site, isn't it? Aliens shouldn't be any different.

The previous paragraph was meant to be a little snarky. I don't have a problem with the math argument for other life, I just don't use it.

Has there been any movement on the Drake equation lately?

I agree, how anyone could state we are the only sentient life in this universe baffles me. Then again most of them haven't any Idea of the vastness of Space.