I have always thought that it was extremely arrogant to think that we're the only life in the universe.
I think it is most probably that we (life on earth) are the only life in the Universe. No one can prove that's wrong. Sure hard to make you arrogant unarmed with anything to the contrary. I also think we got here along with all our companions and their predecessors by the work of God. I see no evidence or scripture that he put his hand to doing equal anywhere else. Kurt Gödel proved to more than my satisfaction that it is mathematically impossible that we are here by any other power than that of God. The man was very impressive, it works for me. That we are here, and here, and alone here, works. Incomplete it maybe, but no one can prove it wrong. Remember, it is more often than not, that truths can not be proven, but still holds true. https://www.prospectmagazine.co.uk/magazine/kurt-godel-and-the-romance-of-logic
Not a matter of arrogance but of logic. Approximately 100 billion galaxies, each containing around 100 billion stars, most with planets, that life would have arisen only on one mediocre planet around an average star in the outskirts of an average galaxy is unlikely. But that is a long way from saying that just because you are not sure what you saw in the sky, it's an alien visitor.
That's all in my calculations. I think the number of stars is even greater than your estimate. There are clusters of galaxies and super clusters of clusters. Then there is dark matter which is approximately ten times greater than the visible matter. And then there's dark energy which may be ten times greater than dark matter. It's still works out to be an tiny tiny possibility of other life in our Universe.
Are you familiar with Drake Equation? Calculates probability of advanced civilizations in universe. Remember also stars are very far apart. Yes, 90% of universe is dark matter/energy but those are not stars or planets, in fact we really are not sure what they are, but are unlikely to support life - so far as we know. Funny how creationists claim to have better science. My challenge to them is to identify dark matter/dark energy if their "science" is so great.
It's more like ~99% given that dark matter is ~90% of visible matter and dark energy equates to ~90% of dark matter. The symbol '~' in mathematics means approximately. Edit: "Criticism related to the Drake equation focuses not on the equation itself, but on the fact that the estimated values for several of its factors are highly conjectural, the combined effect being that the uncertainty associated with any derived value is so large that the equation cannot be used to draw firm conclusions." In all honesty, you could say the same about my calculations but I think mine are more realistic and to date, empirical data supports my conclusion. Edit2: Drake does not take into account that you need a magnetic field to deflect all kinds of solar radiation that would wipe out any life and sweep away any atomosphere. There are a number of other factors that Drake leaves out.
Drake equation is conjecture. It's a best guess. I absolutely know mathematical symbols, @Lanny ! Anyone with science degree took a lot of college level math.
Admit I'm a tad touchy having had it mansplained to me numerous times that women can't do math. Usually by some complete innumerate.
Although that is great to use in explaining mathematical equations, I find it has better uses. For example.... While sitting next to Lanny watching the Blazers game; I squeezed off the most horrific, gut-wrenching fart that the world has ever smelled. ~runs away, laughing hysterically~