The way we see if aliens exist is that we shine light rays at the planets and see if the habitat is in the zone. But the problem is that the light reflected back is millions of years old meaning we see the planet in and how it looked millions of years ago. Hence a lot could have changed in those years
Aliens do exist. The universe is large and vast, or we could say that the universe is infinite. There are countless of stars and galaxies out there, the possibility of not having aliens out there is 0 percent. If that's not enough, Stephen Hawking even had a theory that there are other universes. So we got multiple universe out there. If we don't have aliens in this universe, then there might be aliens in the other universe.
A widely asked question is: Is there Extra Terrestrial life? My thesis is that there is ET (Extra Terrestrial) life. Many other people believe this as well. They believe this because there has been unconfirmed sightings about UFO’s. There is a very good chance that there is lots of bacteria on planets, and bacteria is considered life. Scientists have found running water on Mars, and when there is water, there is probably life. If anyone has doubts about my thesis, think again.
Aliens must exist- they do, actually. I agree with the other three people saying so. But, not only that, there IS LIFE ON MARS. It is called BACTERIA. Why must so many people consider bacteria as a non-living life form? I mean, sure, they're not intelligent, but is all of life supposed to be? No.
And the universe is infinite. So, it is more than likely that INTELLIGENT life exists.
I would have to say I believe there is alien life out there, somewhere. I think it would be a bit odd if, out of the vast universe that we know of now, that we are the only ones in it. I don't feel like that makes logical sense. I think it make more sense to assume there are probably many planets with life.
I believe that in the vast enormity of the solar system and the universe, there is undoubtedly alien life and most likely intelligent life. It seems very likely anyway. With that being said, I don't believe that there is any credible or real evidence that there was ever a visit by extraterrestrials to this planet.
We say that the universe is infinite. And if the universe is infinite than there is a statistical promise that alien life does exist, somewhere. Our odds of ever existing were astronomically unlikely--but still very possible. In an infinite universe this means that alien life has to be out there. We might never contact them though.