The Universe is too expansive to lack anything imaginable.
To us Earthlings, our planet is the most important thing in existence, but in the Universe as a whole, it isn’t at all special. The Universe is massive beyond human perception, and Earth is just an insignificant speck of rock orbiting an extremely ordinary star in an ordinary galaxy in one tiny corner of it.
The Universe is so elaborate, and humankind is so simple. We’re here, worrying about things that are far less than trivial to the Universe. Everything on Earth is relatively small compared to the planet’s size, and the Earth itself is so relatively small compared to even the Sun. Consider its size compared to the galaxy! And how many of those exist? The number is infinite!
Infinity itself is a paradox. It’s problematic because it seems to be more than anything, which means it is something to never be reached. How does one travel from point A to point B if there are infinitely many things along the way? To travel from point A to B, one must first reach half of the way. In order to reach half of the way, one must first reach half of that, and to get there, they’d have to reach half of a half of a half, and so on. It would appear they’d never even be able to start. Basically, there are always stages along the way that have yet to be reached. If things can be divided into infinitely many stretches along the way, there is simply no way to ever travel from one point to the next.
With the idea of infinity, the possibilities are endless. Mustn’t there exist a separate version of the universe for each single possibility? If so, isn’t it only logical that for each one of the infinite number of possibilities there must come another set of infinity- and of course, infinitely more for each of those? It’s like multiplying infinity by infinity infinity times [or, infinity to the power of infinity (∞)∞].
Perhaps infinity is the simplest thing. Because it has no end, and when something has an end, we must define where that end is. The idea of no end doesn’t only stretch outwards; it can fall inwards forever too! You know there are things smaller than us- atoms, protons, electrons, and so on.
The realistic size of the Universe is literally unimaginable. It’s far beyond our comprehension, yet bigger is not all there is. There exist things that, as you know, can only be seen through powerful microscopes- and there must be less. Subatomic particles MADE OF quarks and smaller things and smaller things on forever.
Disregarding the possibility of things (such as alien life) is completely closed -minded and likely very ignorant.
There is so much more to say regarding the realm of possibility, my point is that impossible is often used where improbable should be and it usually results in ME having a MAJOR existential crisis.