The Fermi Paradox - Where all the aliens?!

[Galactus]

More seriously, I'd suspect the most likely explanation would be technological limitations: The speed of light, the capacity for computing, etc. Just not making interstellar civilization feasible.

[Glaurung]

I suspect that the great filter is behind us as the chances of a great extra solar civilization arising are not as high as assumed. For any type of life to develop, hore than hydrogen or helium is needed. Those first stars that were created were almost all hydrogen and only by going supernova did they create the elements necessary for life as we know it to exist, or even for rocky planets to exist. I have never come across an estimate of the time needed for enough planet forming material to be formed as compared to the life of the universe. Assuming a 14 billion year age for the universe, going by our only sample, we can safely say that the upper limit is about 10 billion years. Any ideas on a lower limit?

Another thing to think about is that our sun was not formed in isolation but in a stellar nursery with other stars, meaning all of Sol's siblings would have the same composition and would have planets of solar system type materials. There is the place to look for stars that could possibly have habitable planets, as lots of water ice was available when the solar system was formed.

Metal heavy stars aren't a necessity for creating terrestrial planets. There was recently a terrestrial exoplanet discovered around one of the oldest stars in our galaxy. The star has very little in the way of heavy elements, yet the exoplanet is nearly 17 times the mass of Earth and made of rocky material/metals rather than being a gas giant as expected. So while older stars do have less metals and are more likely to produce gas giants rather than rocky worlds, they still can give birth to potentially habitable terrestrial planets. As for using our solar system as an example, most sun-like stars are going to be somewhat similar to our sun with regards to composition. Some heavier, but most are lighter. Water is one of the most abundant compounds in the universe, so there should be plenty of water available in any solar system. Actually it may be that there is TOO MUCH water in many solar systems, which would lead to water worlds which while adequate for life to form & evolve, would be a hindrance to the development of a civilization.

More seriously, I'd suspect the most likely explanation would be technological limitations: The speed of light, the capacity for computing, etc. Just not making interstellar civilization feasible.

This is my belief. It's likely that interstellar travel is so difficult that few civilizations ever achieve it. Those who do reach that level of technology may be far beyond our ability to comprehend and there would possibly be no reason for them to contact us(if they are even aware of us). Those civilizations that have not reached interstellar abilities will be nearly impossible to detect, unless they were producing an exceptionally strong signal with the intent of directing towards us. If we do ever stumble upon an alien signal, we will probably be the intended recipients. If they're just talking amongst themselves, the signal will be too weak for us to detect/translate unless it comes from a nearby star.

[DaveSumm]

I don't really see why the Type II/III stuff gets taken as gospel so often, when nobody has the first clue how harnessing an entire sun or galaxy would work. Is it not very likely that it's impossible, or at least sufficiently difficult?

I suspect that the 'filter' is behind us as well, most likely at the stage where life becomes intelligent. The environmental 'niche' that favoured intelligence must have been pretty obscure to have only come up recently, almost as if by accident.

[mcbigski]

He might have been using info from the lab in Puerto Rico, which I believe goes off of KOIs rather than planet candidates. A lot of KOIs are probably planets, but a lot of them simply haven't been researched enough to determine for sure whether they are real planets or not and the stars are too distant to confirm by any other means other than a transit.

There was a study done though using Kepler data that came to the conclusion that around 20 +/- % of sun-like stars host roughly earth sized planets in the habitable zone.

It is funny you say this, because Neanderthals did actually have larger brains than modern humans. Neanderthals weren't as social as humans, so their brains developed more towards individual survival devoting more brain power to controlling the body and giving more power to the visual cortex of the brain. Humans on the other hand developed their brains in a social context and devoted brain power to working their environment. This gave humans much more emphasis on imagination and manipulation of the world around us. Neanderthals may have had great computing power and been exceptional athletes, but they probably didn't have much of an imagination. This is kind of shown by the general lack of art found among neanderthals until they encountered humans and started to copy some of their cultural practices.

I really have a hard time believing though that we've advanced as far as it is possible to advance from a standpoint of brain size/power. Our brains have stopped evolving for the most part because it is no longer a survival trait. Where as it was once a trait that was favored because the smarter primates were more likely to adapt and survive, now we have advanced to the point of social efficiency that smarter humans are not really more likely to survive than the less intelligent ones. Few of us face a life/death situation where a few extra IQ points would make us more likely to survive. Those who are less intelligent are also generally taken care of by society and reach sexual maturity and have no problem finding a mate. In fact, less educated people are reproducing at higher rates than educated people these days, so we might be going in the opposite direction. At this point the only way you further the advancement of the human brain is through selective breeding, and that just isn't going to happen. That isn't to say that there isn't some species out there in the galaxy that did go that route and produced a species of walking/talking supercomputers.

I'm not someone who thinks that evolution stopped in the last several thousand years. Intelligence is still a positive trait for reproduction. Even if the dynamics have changed since effective birth control, we're still too close that point to say that less intelligence is a positive survival trait. I suspect that if we were able to compare modern folks to ancient Athenians, for example, we wouldn't be any smarter at the extremes, just better adapted to high density living. There's got to be an upper limit on efficient brain size. How big is it?

I suspect that the great filter is behind us as the chances of a great extra solar civilization arising are not as high as assumed. For any type of life to develop, hore than hydrogen or helium is needed. Those first stars that were created were almost all hydrogen and only by going supernova did they create the elements necessary for life as we know it to exist, or even for rocky planets to exist. I have never come across an estimate of the time needed for enough planet forming material to be formed as compared to the life of the universe. Assuming a 14 billion year age for the universe, going by our only sample, we can safely say that the upper limit is about 10 billion years. Any ideas on a lower limit?

Most of the galatic mass is near the core, yes? So there's a probality that 2nd generation systems with heavier elements formed nearer the galactic center, but they'd also be a lol less hospitial to life since they're much closer to supernovae and random billiard type incursions.

[Jo498]

This is my belief. It's likely that interstellar travel is so difficult that few civilizations ever achieve it. Those who do reach that level of technology may be far beyond our ability to comprehend and there would possibly be no reason for them to contact us(if they are even aware of us). Those civilizations that have not reached interstellar abilities will be nearly impossible to detect, unless they were producing an exceptionally strong signal with the intent of directing towards us. If we do ever stumble upon an alien signal, we will probably be the intended recipients. If they're just talking amongst themselves, the signal will be too weak for us to detect/translate unless it comes from a nearby star.

This is also more or less my position. The advanced civs may just not be interested in interstellar travel, but spend their time meditating or whatnot. It is very naive to assume that all of them may have the attitude of humans since the 16th century that everything should be conquered.

Although it is quite amazing to have witnessed the estimated frequency of earth-like planets going from "we do not know/probably very low" to "very frequent" in less than 20 years, this works both ways.

We may never be able to put it into exact formulae, but it may be that we mis-estimate other factors in a similar fashion. Life, intelligence (at our level) may be much rarer (or extinguished more easily) than we think. AIs may become unstable/inefficient long before the "Singularity" or Superintelligence. No specific "great filter" necessary, just many factors being different from our estimates.

[ThinkerX]

Wow.

I had...or maybe have...the original book on the 'Face on Mars.' (piles of stuff laying around I have not looked at in years.) I'd assumed the 'face'

thoroughly and justly debunked decades ago. That somebody is taking this seriously is...unreal.

[Francis Buck]

Yeah that's kind of hilarious, but I'd be lying if I didn't say some small part of me wished it were true, just because I want to know about some fucking aliens. I would be so psyched if we discovered that Mars was at some point inhabited by complex life (doesn't even need to be that smart, certainly not human-level, I just can't imagine how amazing it would be if we started finding fossils of animal life there). Having just ONE example of life outside of our planet would seriously be such a huge, huge deal in so many ways. Hell, even a single bone of a single extinct alien would be mind-blowing and would have massive ramifications on our knowledge of life in general.