I'm with Brian Cox; his hypothesis is the best available explanation for the problem that (1) life is apt to be plentiful and (2) we haven't encountered evidence of other sentient species. There are other potential reasons of course, but SOME form of "hard stop" evolutionary brick wall can very well exist. We humans seem to have gotten past several of them as it is. Maybe we are luckier than we realize even to have gotten to homo sapiens much less having the opportunity to out-engineer ourselves.

Of course we have no hard evidence of even simple biological life in our own solar system apart from what's on Earth itself, so we could be over-estimating the probability of life arising at all. It's just that it'd be hard to over-estimate given the near-infinite number of chances a near-infinite universe gives for life TO arise.

The truth is, the universe is big, and our data set small, and we don't even have a good scientific understanding yet of how life arose here, much less anywhere else.

I absolutely think there is intelligent life elsewhere. How could there not be? How many times could conditions on earth have been duplicated on other planets? I believe there must be intelligent alien life, far more advanced than we are, technologically. Beyond that, I don't see how anyone can speculate on alien extinction with absolutely zero actual data/information.

My feeling on why we haven't been contacted is that we are still too primitive. We are beneath their notice. Gonna get a little cheesy here and use a Star Trek analogy. In the film First Contact, earth attracts the attention of a Vulcan science ship when they test "warp drive." I wonder if there is some interstellar communication system humans haven't discovered yet, but will. Who knows.

stating that we are alone amongst so many stars, without any evidence to support your opinion, is both arrogant and naive. The fact that we exist on this floating rock in space in a tiny portion of the universe should be ample evidence that the scientific possibility exists that we are not alone

I really hope we are not alone. Drakes equation gives me hope.

Space is a big place, I'm pretty sure there is intelligent life out there somewhere, but I'm pretty sure we won't see them on earth, because as I may have mentioned, space is a big place.

It's egocentric to say no, and a leap without evidence to say yes. I'll wait and watch.

I don’t care but tend to agree with Brian Cox.

I can't say for a fact because I don't know, but I highly believe we aren't alone in this world.

It's a BIG universe. Surely we are not alone here.

But like I said, it's a BIG universe. We might never meet another intelligent life form.

Unless the lightspeed problem is solvable (and physics claims it isn't), we will never see the great empires (or Federations) of history, and will be hard pressed to get out of our neighbourhood.

But to think we are alone is the ultimate hubris, right up there with thinking we were made in a supreme being's image. Or that a Middle Eastern Jewish messiah was white.

Why is it that we think any alien civilization would be so stupid as to follow the foolishness we perpetuate on ourselves. I would like to think that being alien means that they would be different than us and so have a completely different set of problems and solutions. Also could it be that we have not been contacted because they are watching our present political situation and laughing their asses off. Assuming they have asses. It could be that there is no way to get past the speed of light. They are further away than 50 light years. We are not interesting enough or intelligent enough for the effort. We do not have anything worth the effort.

I think Cox has the right of it, although I think 'breeding themselves into a complete planetary meltdown' ought to be danger number 1. Still the universe is so vast, there are bound to be other intelligent races. But communicating with any outside our local area of the Milky Way is likely to prove impossible, and we'd have to get lucky for there to be any that are that close.

I'd recommend David Brin's Existence as a science fiction novel which does a decent job exploring this and other aspects of the Fermi Paradox.

More than likely,but guess we will have to wait til theyre ready.

I have been obsessed with the Fermi Paradox for a while now and more and more I'm coming to think that the notion of the "great filter" has merit. That there are some laws of the universe that either cause emerging civilizations to die off (via the advent of a dangerous technology or perhaps the fact that evolution leads to selfish competition that destroys the ecosystem of developing races) or that we may be one of the first to get this far.

The latter seems unlikely until you start viewing all the ways that spacefaring races can be stopped before they even begin. Needing a cycle of life that leads to oil being available to future species, having a plant that can be turned into rubber for insulating electronics, not being on a planet that's so large that gravity makes it inescapable by rockets, and countless ways a planet can die from unbalanced life or external factors before intelligent life can emerge. We may just have wound up incredibly lucky here.

Simply seeking extra terrestrial life is to limiting in the search for aliens. Quantum theory would suggest at least extra dimensional life is almost an inevitability, life on other frequencies outside of the range of human perception is another possibility even alternate hominids that have simply decided to stay away from the dangerous monkeys with their bombs and pollution and stupid religions.

I think there has to be life beyond our little planet. The universe is far too fasinating and complex for this to be the only planet to have life.

I think life forms can exist without a platform that earth humans are based on. This notion that they all should look like us is egocentric.
Heck, I suspect we wouldn't even recognize these other life forms so any contact really is simply dreaming.

Well why do you think Trump wants a space force? Cause them aliens need Jesus and democracy(in other words they probably have oil)

According to secret government whistle-blowers, I've been reading about since the 1950s, the US government has been in cahoots with aliens and their technology sincen WW ll, but keeps it classified, suppressing all UFO reports and ridiculing people who report them, so they don't have to share the technology. It must work, because most Americans seem to believe the US government.

The documentary, "Unacknowledged" - seen on Netflix and Youtube-has videos of US presidents, scientists, astronauts, NSA officials, even Obama and Hillary, acknowledging the US has this technology but is keeping it secret.

Besides, I've seen hundreds of UFOs, usually with a witness or even with groups of people, both in Haiti where I grew up, and in the US during the 1960s-1970s, but didn't see much after that until one obviously human-derived UFO flew over my farm in 1998, when I was star gazing with a date.

It was about the size of a small house, and rotating slowly as it flew at low altitude. I could see through the oval portholes that it was lit inside.

American people puzzle me how brainwashed they all seem to be, calling UFOs nonsense, when they are taken for granted in many other countries.

Doesn't take much imagination to recognize tha the early Mesopotamians had writing, sewers and government etc... WAY before anyone else...

It is my theory that the elite shadow controllers (probably Not directly aliens)
Are aware of intelligent aliens visiting the earth.

I THINK It is possible that the pretty much " mind their own Bussiness when it comes to local planetary conditions (politics etc)...

My theory goes like this:
Take local primates and manipulate genes with alien components and set them loose on a dirty planet and let simmer...

Why? Because they could have low immune systems (traveling in sterile conditions etc...) ...
Our excelirated anti bodies (survival of the fittest) could have great viral value...
It would explain abductions...

Also our germs could be biological agents against selected enemies...

So I think they May have made it clear to goverments, that humanity (with our virulent toxicity... ) represent a biological threat to the universe...
Therefore they don't care what we think or do as long as we don't KNOW what they want...

And that we do Not make it off our quarantined world...

(Thus the Death of our space programs...etc

Yes, they cross the border all the time !

Probably they exist, but are too far from us in space and time (technological level of evolution), to make proper contact.
In theory there are other intelligent species in our planet, some tribes of chimps and other apes are already using tools and primitive weapons, this puts them already in pre-historic level of civilization. But they are in a level so different from us that we can't communicate properly. And this is some tenths of thousands of years of cultural evolution only. Imagine that at the space level there can be civilizations billions of years ahead or behind us.
So as we narrow the precision of the factors in Drake's equation we start having an idea of how many and how far in space and time we are from other reachable civilizations and how (if possible) long until we contact them.

arms and legs are not necessary for intelligence. porpoises are intelligent!

if there is intelligent life elsewhere (i am not sure it's here!) it is sufficiently far off that we are still alone. i am not sure we are intelligent enough to recognize it if we find it.

g

I have been stranded here for 13 of your earth generations and I am tired of re-inventing myself. Fortunately human society has become so diverse and fragmented that I can say this with total confidence that it will be regarded as a joke and I will be in no danger. I met this guy called Gene back in the early 1960s and the bastard stole my story and turned it into a TV show without giving me a penny. Hopefully the Federation is still going but either way this is still a quarantine system so until one of you lot hops a star I'm stuck here. And no I can't help you do it. PD and all that crap - but quite frankly I'm tired of this primitive place.

I'm a simple man - not a deep thinker and one who believes that the simplest answer is likely the right one. This is what I think about this issue - let's assume that 14 events needed to happen for life to come about here on earth e.g., climate change, bombardment by asteroids containing water, our planets' axis of rotation, gravity, the ozone layer and how all these things came to be following other events that occurred. There are many others that could be included here - I'm simply not that smart - however, take just one away and we wouldn't be here. And so the idea that all of the 14 events that we needed to exist - by default, exists on another planet is just not something I can accept. Is there alien life - sure - but we're the most advanced because of the unique circumstances that made it possible for us to exist. We've not been visited - Star Trek and Avatar are science fiction and until one person comes up with a CLEAR picture of an Alien or UFO - I'm gonna stick to my simplistic views.

We may have been visited in the distant past,paintings,carvings,statues,all seem to point to beings in vehicles,perhaps affecting how Humans have developed? The Pyramids in Egypt,and very similar types in South America,coincidence?