Yes, I believe they exist. Do I believe they’ve visited Earth? No.

Yes/no is less interesting than your reasons for your answer. And most importantly, what impact does your answer have?

For me, it’s a no. Because there’s no hard evidence. And by not believing, I save a lot of time and lose absolutely nothing.

That isn’t to say it’s impossible. It’s to say nobody has show me where it’s probable, based on hard evidence.

And to those here posting that animals wouldn’t count because they’re not intelligent: you’re wrong.

Here and now? Doubt it. Out there at some time. Seems likely.

Life on other planets? Seems likely.

Life on earth started pretty soon once the conditions were met.

Intelligent life (humanlike), maybe not. Most probably not. Out of millions of species through billions of years only humans have evolved to have this kind of thinking machine during a relatively short period of time.

They are hiding in Antarctica under the ice.

That depends. Yes, I believe it is probable that life exists elsewhere in the universe. But no, none of that life is building pyramids in ancient Egypt, abducting cows, or anal probing hillbillies.

Depends what you class as “alien”.

Given that there are literally billions of galaxies out there and each one contains billions of stars with each one having the possibility of its own multi planetary system, it would be rather silly to assume that on our random planet of literally trillions of others, it’s the only one that life has or will evolve on. It might be not be life that has the ability to read a post on a smartphone but it might be more simple. It might be more advanced but I’m sure there’s probably some form of life.

Whether any have been able to build inter-planetary/or inter-galactic vessels and travelled to Earth…highly unlikely. And we shouldn’t be so conceited that if they did come that they would come for us! We’ve only been around for a million years. We’re relative newcomers on the block.

He likelyhood of this planet being the only place in the universe some complex proteins folded a billion years ago is zero.

Giving the size of universe, there is problably life on other planets, too.

Yes but I don’t believe they figured out how to cross the distance/time vastness of space.

I’m actually kind of excited for what we might find in the oceans of Europa. You never know!

I’m an alien. I’m a legal alien.

I think it’s likely aliens exist, but unlikely any alien species will be what we expect. I highly doubt we will see humanoid “little green men” or anything like the majority of science fiction portrays. Each planet is vastly different in just our solar system. The vast differences in environments across the galaxy will yield vastly different paths of evolution. We are only looking for “life” that fits our narrow definition based on Earth’s species - we have likely already missed signs of alien life.

they definitely exist but they’ve never visited human civilization

I specify human civilization because I think it’s possible that aliens may have visited our planet before human civilization but that their visit was so long ago that it is impossible to tell the evidence of it from random noise - like imagine if a space probe was in our orbit at some point a million years ago, I don’t think there’s any way that we would be able to tell, and declaring it to be true or untrue one way or the other is kind of a Russell’s teapot situation.

The universe is too vast to not have some other life, but they’d be smart to avoid earth