I think This immortal song from Monti python, says it for me, the one which in its last line reads "you better hope that there's intelligent life out there in space, because there's bugger all down here on earth!" .

But to actually seriously answer the question, yes, the universe being the size it is, the possibility of there not! being life seems pretty remote, so logically some must be intelligent in some way, though how similar to what we call intelligence, who knows.

Still, the last iteration of the drake equation I heard predicted about 300 civilizations in our own galaxy, albeit the drake equation has so many unknown variables it really should be called the drake set of highly modified educated guesses .

I do, because me and my family have has experiences with UFO's etc. And other things.

I can agree with you there dark

I mean, "believe in" is a weird way of putting it.  We know beyond all shadow of a doubt that evolution works (we can do it on a small scale in the lab).  We know beyond all shadow of a doubt that there are other planets like Earth.  But--well.  The drake equation isn't the worst thing.  The worst thing is that if you assume that every technological civilization sends out probes, and they always point their probes toward other habitable systems, it's really weird that we haven't seen any.  The universe is kind of incompatible with there being extraterrestrial life but there not being a galactic empire, because even without FTL you'd probably have something somewhere that lives long enough not to care, or automated exploration probes that can build more, or at least one civilization that's built some sort of artifact that we can see from here.  This question is called the great filter: what stops life from getting to that point?  No one knows.  Maybe life is rare.  Maybe intelligence is rare.  Maybe civilizations end up nuking themselves, or bacteria kills you off, or any number of other things.  But you'd be hard pressed to find a scientist who would say with a straight face that extraterrestrial life doesn't exist.  There's even tentative evidence and arguments for microbial life on Mars in the past.  Whether it's possible is pretty much a solved question.  The interesting question is why we haven't found it.

@5
You're going to find out one day that experiences with UFOs is probably someone was on all the drugs, or they also believe that lizardmen exist, or any number of other things.  The reason scientists don't go around looking for them is because they don't make sense in the slightest: if you have that technology you have much better things to do than fool around with the humans while also keeping yourself hidden, but they also act in ways which science has ruled out save for godlike entities, and again UFOs don't make sense for godlike entities either.  I'd use this as a learning moment and go learn about why UFOs are ridiculous and what other explanations there are, because if you go around saying it when you get older people will laugh you out of the room with good reason.

The biggest one though: getting here from the nearest habitable planet would take hundreds of years one way.  FTL has been ruled out pretty conclusively.  People say "you can't go faster than the speed of light" but that's actually a lie to children and if you want to understand the real thing you need to learn about general relativity, which is very very complicated and the very little I know gives me a massive headache.  But basically you can leave home for Alpha Centauri and maybe you can work out how to accelerate so that time dilation for you lets you get there and back in a couple days--that's not likely, but let's play devil's advocate here--but it'll still be around 10 years from Earth's perspective.  It's not something you do casually.  If you decide to visit Earth from wherever, you need an incredibly good reason.  Casually traveling the galaxy isn't possible, and if you're coming from far enough away that our telescopes can't easily find you, it's going to be hundreds of years back home.  And, to do that invisibly would require absurd levels of tech.  Your deceleration on this end would be visible to every observatory on the planet even back in 1900.

So, assume you're that sort of civilization.  Somehow, you have antigrav tech and the ability to entirely cloak your UFO and whatever, a bunch of absurd stuff that probably can't be done.  You wouldn't visit us in secret because the one thing you still can't do is get here and back quickly.  If you wanted to conquer us for resources, you'd take a rock, aim it, and accelerate it to the speed of light and just not bother decelerating on this end--we can't defend against that at all and it'd kill off 99% of humanity while leaving all the metals and things here for the taking.  Hell, we couldn't even see it coming.  If you wanted a dialog, you'd just show up because if you had the tech to get here, there's literally nothing we could do to you at all, in the "I have a sword and you have a missile" sense.  If you wanted to experiment on us, you'd just take a city because again there's nothing we could do to stop you.  Aliens can be as alien as they want to be, but at the end of the day every society no matter how alien has resource constraints, and just sending one UFO is going to cost their equivalent of trillions of dollars when they could do everything they might want for half the price by just showing up in the open.

Everyone has already pretty much stated my thoughts. There is no way, and I mean no way, that we are the only life in this universe. I find it absolutely impossible for that to be the case. There is something else out there. Where that life is? Who the hell knows. But it is out there. It has to be.

@10
Not really.  It's highly unlikely that there are additional forms of energy which can be used as transmission mediums.  There are also ways to tell whether or not a signal is artificial without knowing what the content is, and those particular mathematics are prerequisites of things like computers.  You may not know what the other side is saying, but you can definitely know that the other side is saying something even if you have nothing else in common.  If the other side has the tech to build a transceiver, they have the tech to know they're receiving something artificial.  The problem with sending is that the sky is really really big.  The chances of us hitting something else alive that also has a transceiver aimed directly at us are pretty low, and if we did the round-trip time for the message is 50-100 years even in the best case.  If someone has responded, we might know in the lifetime of your grandchildren, provided that we also happen to still be listening in the right part of the sky.  For all we know someone got our messages, or will 20 years from now.  But that's not why these questions are open.

These questions are open because when we look we can't see life.  Life changes the atmosphere, which can be observed through telescopes.  We can actually tell what a planet's atmosphere contains using spectral analysis.  Life with a tech base is going to send out radio signals that are pretty unambiguously containing information--they might not be listening, they might even be long dead, but "hi I have TV" is pretty easy to tell.  We send out probes all the time and we're barely getting started, and yet somehow we haven't ever found even one probe from someone else--if there were lots of someone else's sending probes, well, it's really stupidly easy to detect Earth now, and we've been detectable for well going on 1000 years as an intelligent civilization and for well going on 20000 or maybe even 50000 as a planet that's definitely got some life, possibly even longer than that.  Any advanced tech civilization will have all sorts of orbiting things and whatnot that we should be able to see--we have some ridiculous number of satellites ourselves, and honest to god plans to colonize mars in the next century because why not?

And that's just the ones I know of with nothing beyond a casual interest at one point in the past.  "here are 10 different ways to detect life.  We know life is possible.  Watch what happens if we put some hydrocarbons in a jar and apply some electricity.  But they all come up blank" worries a lot of people, and rightly so.  Where is it?  Whether or not we can understand each other is the boring question.  We have enough physics knowledge to actively rule out certain tech branches now; we're no longer in the era of science where we'll discover how to build wormholes at any minute, along with telekinesis.  "They're so much more advanced than us that our sensors can't detect them" hasn't been on the table for a long time.  And yet...nothing.  Not even evidence that there was something in the past that died off.  The most optimistic answer is there's something that kills life before intelligence happens, and we got past it.  The neutral answer is that life just isn't so common as we think for some reason or other.  The "isn't that scary" answer is maybe we're still before whatever kills civilizations kills us.  The "this is a science fiction novel but we can't rule it out" answer is that we really shouldn't be so loud when it comes to things like radio signals because something is listening and actively kills off life.  No one knows, but everyone agrees that it doesn't make sense and that something in our understanding has to be wrong somewhere.

@13. Completely fair
my question is, how much do you know about the universe, at least in the scientific aspect? As a computer scientist, you know more about technology but think of this. Besides astronomers, our only form of interacting with outer space are the probes we've sent out. Take into consideration that the first telescope was launched into space in 1968, around 52-53 years ago. As a technology person with a knowledge of mathematics, would you say that that amount of time is enough to find civilizations? maybe they received our signal but maybe they aren't that advanced and they are either still in their stone age or renaissance period. I do agree with you that life maybe rare but I don't believe that other life doesn't exist

So, we have technology, but they have way way bettor technology. So first, they probably have tech that can just block hours so we can't track see or what ever. Because i mean, if they have UFO's and can fly in and out of those, probably have teleporter's. Then that's like hundreds of years of science for us. So their real, and people have seen them.
The problem is imo is that other people don't believe, and i no it sounds crazy like, hey i just got lifted in the air in a bright beam of light and put to sleep and a few hours later i woke up in my living room on my couch or something.
But they also have the tech to just do anything tbh, i mean they could probably mind control us. There probably watching us, they can hack us also probably. I mean, anything.
So what i'm trying to say, if they don't want us to find them. Then we won't find them.

I completely agree with khomus on this one.

@15
So the thing here is: FTL is impossible.  Weird new forms of energy we don't know about yet are maybe possible, in the sense that technically speaking we can't disprove it but science is pretty strongly leaning toward no.  You've got to keep in mind that at this point we're literally playing around with particles that only happen in stars and places like that, and even then only rarely.  Even if someone did have communication that's somehow mysterious and magical and doesn't need electromagnetic radiation, they'd also have had to get there without going through any of the other stages and be making an active effort to hide--and what about the other 9 civilizations?  The claim isn't "this one hid" if you want to go there, it's "somehow everyone but humanity did a thing that we couldn't do".  "they're mysteriously invisible" only works if you say "life is rare", and since you're saying life is rare either way it kind of doesn't matter.  Same thing if you keep missing it with your telescopes--the longer you look for something and don't find it, the rarer the thing is.  Doesn't mean you won't find it tomorrow, but the longer you go without finding it the more that tells you about how common it is and then you can start putting upper bounds on how many there have to be.

But I'm *not* saying it isn't out there.  One of the theories for example is that life is rare and that civilizations just last for maybe 50000 to 100000 years, for instance.  The universe is billions of years old.  If there's only a couple civilizations per galaxy every million years, it's possible that you just keep missing each other and by the time the next one is looking around the first one has been dead for long enough that we can't see it.  There's a lot of theories that explain this without saying no life, and as far as I'm aware, no life is all the way down at the bottom of the list, but at this point no one is saying it's common because even the most basic analysis of this stuff makes it really clear that it isn't.

If you want to know how I feel on it, finding extraterrestrial life tomorrow wouldn't change anything.  Even if we did, we can't share tech or media or anything like that.  "how do we build a cold fusion reactor?" goes out and we get the response 200 years later and in the meantime we just went off and built one, or it was too hard and we had to wait 200 years longer for the clarification.  Our art and literature probably wouldn't make sense to each other.  We could start go exploring the galaxy but not without something like brain uploading.  Short of that everything is too far away.  You effectively have to be immortal for it, and all the ways in which you can do it without being immortal mean that whoever leaves won't come back to anything they know--not just family, but nations, even the organization that launched your ship.  Quite literally, you may very well come back and have everyone go "wait, what ship?".  Lots of interesting destinations are a couple thousand years away, Earth time.  It might change religions a bit, but mostly people would probably just go "well god made them too" or whatever and it'd all blow over after a couple years.  I don't know for sure why we don't have every scientist or whatever on this problem, but I'm pretty sure this is why--if you already know it's possible, but you understand just how big the universe is and how little finding it would matter, going off and curing cancer or whatever is way more important.  Maybe 500 years from now, when we're all running on computers and you can send spaceships the size of a laptop out, that's when finding someone might change things for us.

If you haven't read the Wikipedia article on the drake equation and the great filter, those are good places to start if you want to get some idea on how people who know about this stuff think.

@13
Have you read the Revelation Space series, by any chance?

@14
Speak for yourself! I like to think I'm doing my bit for the environment, although I don't do everything possible it is true. There are lots of environmentally-conscious people on Earth, but the only ones that make it into the media are the outspoken ones, and it's easier to demonise them so that Joe Public can keep buying plastic bottles from the corner shop to drink water from, and cheap plastic clothes that'll fall apart (but not biodegrade) in about 15 minutes, than to admit that maybe they've got a point, and maybe afore mentioned Joe Public and friends are selfishly screwing the planet for their kids because they really can't be bothered getting off their collective arses and walking for 10 minutes.

Also, if I'm being honest, many of the people who are trying to save the planet are going about it in completely the wrong way, blocking off meat counters and the like. That wins nobody. Although, that said, as you've pointed out, humans are inherently selfish, stupid, and self-interested, so maybe the correct course of action would be to just shoot anyone you see buying stuff with too much plastic in it, or driving their car less than a kilometre in the face.

@15
You're forgetting that telescopes have a limited field of vision. That's like pointing a laser out across the sea and hoping to blind someone when you don't know when or where they are on the opposing shoreline. Also, we have gravity detectors too, and probably loads of other stuff I'm not aware of.

@16
Sure, it's long been established that there are no fish in the sea because if you go for a swim, you might not notice any.

Also, there's mass hysteria and the human propensity to conflate and change stuff to suit their own ideologies ETC.

Probability isn't about faith, it's about "if you want to build a vehicle that rolls down a hill, using square wheels is a shit idea".

@17
I'm sorry mate, and this is coming from a place where I sincerely hope there's that kind of tech in the universe, because teleporters and arc ships and FTL and the ability to rig a black hole up to be the only computer civilisations would ever need again would be amazing, but you sound like someone who smoked far too much of the good shit once, or experienced Hypnogogia once, and then spoke to some like-minded folks, and your memories all fell into line because human memory is notoriously fallible, and nobody wants to be excluded from the herd.

Sure, let's take for a second all of that stuff is possible, but what's the point of it? Why build a galaxy-spanning civilisation only to spend your days burning the proverbial ants with a proverbial magnifying glass? (Wow, I just saw 18 already said that... Conspiracy anyone???)

@everyone
On this subject, this very morning, I was reading this. I think the aliens put it there to remind me that scientists don't know everything.

Also, this Easter, watch out for Jain eggs.