The universe is just too big and too full of possibilities to think we’re the only ones. We know life can happen—because it happened here on Earth. That’s not just a guess; it’s a fact. And the basic ingredients for life are everywhere out there: water, carbon, organic molecules. We’ve even found life on Earth thriving in the harshest, weirdest places imaginable.
So while we don’t have hard evidence yet, it’s not a stretch to believe we’re not alone. Honestly, with billions of galaxies and trillions of planets, it would almost be stranger if we were the only ones.
NHC
I mostly agree, however, it's important to look at the time, too.
Like, look at the universe and actually observe how much of it has been touched by time according to any given part of it.
Our universe is only something like 14 trillion years old.
Our planet is 7 trillion years old, and existed pretty early for what it is (a terrestrial planet with water around a second generation star that had a goodly amount of intersection with various stellar ejecta), and only now is intelligent life first getting a chance to wipe itself out properly for the very first (and possibly only) time.
A few times in the past, life did that thing, nearly wiping out all life because something did something blindly and other stuff took a while to learn to eat the byproducts.
This means while life is almost certainly "out there", intelligent life is almost certainly very far away at this point.
It will be a while before life makes contact with life, I think, and I doubt travel may happen promptly, with few opportunities even over billions or trillions of years to exit, and only to "close" places.
The Andromeda flyby will probably be the next possible opportunity for anything to cross the intergalactic void.
In the space of time in which the interfacing happens, it may be possible to rendezvous with and slingshot off of a passing star to go any which way, at intergalactic escape velocities, so as to rendezvous with a third galaxy, and to reach any number of interstellar targets in both Andromeda and in the Milky Way.
This won't happen for a very long time, but this is probably the earliest I would expect visitors, or maybe a few (hundred?) thousand years after.
My bias is to expect alien life in the form of something compact and slow-acting that takes root in remote places that don't support a classic view of "life" arising organically there.
From that perspective, we wouldn't even know it was there before it had a colony among the Jovian Trojans or moons or an asteroid belt or whatever the case may be for whatever works best.
If you can imagine AI terminators or whatever taking over the earth... Why would they care about the earth when they don't need an atmosphere, and there are better resources in space, assuming they have the delta-v to get where they need to go? All the rest is just computation of curves using known equations, and periodic course correction applying those computations.
It is one of the most unburdened ways to exist.
There are no predators.
There are no real time constraints.
It's just you out there in the void until you are big enough and have the resources to grow and put together biochemistry, or possibly collect some samples. If I was gonna do it, I think I would try to get a firearm barrel into the upper atmosphere with a balloon and attempt a bullet catch using a slug whose innermost lining is an aerogel filled with the sample, and fired at a known coordinate in the sky above the planet. It might eventually come back down, were it not to be caught by the actual exit craft.
Then I would grow one of those best I could, drop it down to the planet, and regularly transmit back until I had lived a few lives and probably wouldn't make contact until they were messing about and could possibly end up angry I already ate all their best space rocks.
And by "I", I mean me and whatever species I'm from and whose members were representing me in the scenario.
Getting across the interstellar expanse is very difficult, even trying requires some very advanced traits, and "being something that could survive where you are going" requires even more still.
I personally think much of this will come in the next 100 years, and we will already be "digitally commuting" at light speed around our solar system.
Whether we find something has started eating all the best space rocks before we got there is an open question, but as I said we are pretty early. I would bet even the first life to ever become as we will say "how can we possibly be the first? Are we the first?" And will go out into the universe to find some other life that has likely thought much the same for almost as long, even if they find younger life thereafter.
It will happen to many, infinitely many, in fact, to feel such as we might actually be.
