Is It Irrational to Believe in Aliens?

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Aliens! Could humans really be alone in this expansive universe? And if we're not, how come we've never made contact with other intelligent life? Everyone's thought about it; especially members of the scientific community. Join Gabe as he presents some of the most popular theories that scientists use to rationalize their support or skepticism of the existence of aliens. We may never know the answer to this age old question, but a little scientific thinking never hurt anybody!

Extra Credit:

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Comments:
D. Moritz

Gaëtan DO VAN LANH via Google+

The Gentleman Physicist

Nicholas Feeley

James Morgan

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Hosted by Gabe Perez-Giz

[TurboSol]

What SUCKS big time is the fact that I almost certainly won't live long enough to find out, the main reason I want to live for hundreds or thousands of years is to see how advanced science gets and what we discover about the universe, I need some immortality drugs Asap

[sacr]

I feel they're not taking into account the size of this Galaxy.. Even if lets say 1000 species survived to the point of spreading their technology via satellites throughout the galaxy, these objects are tiny.. and we're talking 4-10 light years between each star system.. with an unimaginable amount of empty space and so many directions it could go.. The odds something comes close to our planet is insanely low..

And even with radio waves, lets assume they use radio waves as a primary comms tool for 200 years before advancing to a new technology. Then lets say 1000 species used it, at different times throughout the 10, 000, 000, 000 years the galaxy has been here..

Thats what, a 1/10, 000, 000 chance we'll hear it in our time here..

I don't know, there is just so much time, and so much space. People always forget how damn big it is.

[dolebiscuit]

The Fermi Paradox is pretty much bogus if you apply logic:

1. We've only been actively listening for alien radio signals for about 50 years, and passively listening for them for only about the past 100 years. Assuming an alien radio signal from 50-100 light years away happened to pass by us, it would be so unrecognizable from encountering 50 light years worth of material interference that we likely wouldn't even know what we were looking at.
I mean think about it; the signal would have to pass through 50 light years worth of stars, solar wind, space dust, nebulae, planets, moons, asteroid fields, etc. before it even reached us.


2. Even if a civilization were highly advanced, and decided to visit EVERY SINGLE star in the galaxy, there's still a large chance that no artifacts would be left behind for us to find, because the likelihood of a species sending a manned mission to every single star in the entire galaxy seems extremely unlikely to me. Even if they only sent 3 people per star, that's 600 billion people to send out.
They would more likely send probes because they take far less resources, impart no risk on the user, and probes won't say, "Screw that, I don't want to do that." Probes would be unlikely to leave behind artifacts--like a can of Space Pepsi or a half eaten bag of Cheetos.

3. Advanced civilizations probably have a higher regard for not polluting the entire galaxy with their garbage.

4. Our Solar System is vast and mostly unexplored. We can hardly detect near Earth asteroids, and the ones we do detect are due to the thermal radiation they give off. You expect us to spot what would presumably be a long decommissioned alien probe sitting quietly somewhere in our enormous Solar System that we've barely explored? How hilariously confident humans are.

5. Advanced civilizations may have no interest in communicating with us, as they see us as too primitive.

6. Advanced civilizations may no longer use primitive radio communications.

7. Any evidence that they potentially could have left behind--either here or on the Moon--would be actively suppressed by the government or misinterpreted by historians as ancient myths about gods that descended from the sky.

[chrisbow]

I recently read a stat that scientists studying planet formation have estimated that the earth is probably in the first 1% of all habitable planets that are likely to form in the milky way. That despite the fact that the sun is not a first generation star is not the point. Bare in mind that it took generations for some of the more complex elements to form. So it may be that we are actually "the ancients!" or at least early bloomers.

[pankajnegi]

Calvin : "Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us."

[rahulshetty]

The absence of evidence is not the evidence of absence

[iwolfman]

Maybe we're all just looking at this the wrong way. We all assume it has to do with space rather than time. Think about it this way. The universe is roughly 13.8 billion years old. Our planet roughly being 4.5 billion years old. This alone means the universe took roughly 9.3 billion years to form a fitting planet for life. But there wasn't always life on Earth. It's estimated that the Earth took around another half a billion to a billion and a half years to even form the very simplest of life on Earth. As for complex life ? Roughly 3 billion years after the Earth's formation. Altogether, this is already roughly 12.3 billion years into the universe, already just under 90% through the current lifespan of the universe and this is just how long it took to create complex, or in other words, multi-cellular life on Earth. What we currently would classify as animals didn't even form for another billion years more or less. To keep this into perspective, we are now just over 96% through the universe's history to date. It took that long to form animals, not intelligent life, animals on Earth. Another 494 million years however, for what we call are our ancestors to have been born. And then another 5.8 million years to evolve to what we consider the modern human. Intelligent life on Earth took over 13.8 billion years (earlier I rounded down because the current estimate for the universe's age is 13.82 billion years). We, as a race, are literally not even a percentage in the universe's lifespan and we expect there to be more intelligent life ? For all we know, we could be the first intelligent life to have formed. Or we could be racing against one or more intelligent life currently, they could be in our galaxy or outside our observable universe. We may have spawned in a renaissance of life, we may be the pioneers, we may be late to the party, all other life could have gone extinct for already for all we know. But it's harsh to deny the existence of others when we ourselves, or at least what we classify as the modern human, has only been around for the past 200, 000 years.

[zacharyhunt]

I liked the Great Filter theory. I've had two thoughts on this subject. One originated from the book "Speaker of the Dead." They find a less intelligent (yet still sentient) civilization on one of these new planets. However, in order to observe how the civilization would naturally progress on its own, the humans severely limit this new species' exposure to advanced human technology. So what if there's a greater intelligence watching us, yet they leave no trace for us to find because they dont want to effect the advancement of our civilization. I mean just seeing an intergalactic spaceship would effect the future progression of technology on this planet.
My second thought is, what if the universe is still relatively young? what if we were one of the first types of life to evolve into intelligent beings? That there are other intelligent creatures in the universe, but they're just not any more advanced than us? Idk basic ideas i guess but they make sense to me.

[tamara_kama]

I think a problem with finding extraterrestrial life is basically the speed of light. Most of what we can detect in the night sky has arrived to us from countless light years and we're seeing into the past.

So there actually could be more out there than we can detect but we can't detect it in real time. We certainly can't communicate with them in real time. Civilizations may have arisen in a time frame that doesn't allow for them to even get a message out that we can receive.  By the time they do and if\when it arrives we may actually be extinct!

This problem is compounded by even more distance.

I don't want to sound pessimistic with that but I think it's irrational to think that if Aliens are out there then we must have contact with them by now or else they don't exist when you consider the above.

[brucecrawford]

What if advanced civilizations have managed to transfer into other dimensions? Which is why our perception of space appears empty. Maybe all the advanced species are all heavily populating another dimensions. And whenever we figure out how to travel there ourselves, well bump into another spaceship and they'l say "damn, about time the humans showed up, took y'all long enough" :D

[dimitrijeandjelkovic]

I have 3 ' theories ' :

1. Since humankind is such a young species and our modern science and technology even younger, there is a possibility that there are highly advanced aliens in our galaxy that at some point in the past, when we weren't even existant, left the trails in the galaxy we try to seek today now that we are advanced enough, but in the meantime, let's say when we were still just cavemen, they might have observed us and knew that we were gonna be the dominant species on planet Earth so they decided to ' clean up ' all the trails, all the ' stuff ' they ever left in the galaxy, because maybe they just find us too primitive and not still ready to know of their existence. In other words, maybe they just don't wanna be known to exist, not quite yet.

2. On the other hand, we could be a bit imaginitive and just say that they are maybe a species that are fundamentally spiritual beings, not materialistic, therefore, they don't have the ' stuff ' to leave in space and yeah, they don't make contact with us because either they don't want to or their spiritual origin makes us unable to see them, communicate with them or interact in any way.

3. This ' theory ' is a bit conspiratorial...maybe there are, for instance, 4-5-6 highly advanced species in our galaxy that have already communicated amongst themselves and created an alliance that intends to unify our solar system and in order to do that, they formed a council with their representatives/ambassadors or something. They all agreed that no species should let humans know that they all exist, so they all agreed to that, because they find us unready. It's like in Mass Effect video game series.

All in all, don't you agree that if there are species advanced enough for interstellar travel, wouldn't it be easy for them to hide there existence? I think the possibilities are endless as to why we have zero contact or proof of their existence.

[manusartifex]

This guy got his shirt from target, I have it too.

[yournevergunnaknow]

This video is easily the best unbias video about the likelihood of other life in the universe.
I could talk about space for days but this video sums it up pretty well!
I agree with the theory that life is common but wipes itself out before it gets a chance to spread very far into space. Long term we cant keep going the way we are, we'll eventually run out of resources leading to more war over fuel, land and water. If we don't kill each other with war we're going to destroy our atmosphere, eventually making the planet uninhabitable before we get a chance to get off it.

[thedivide]

Correction: the covenant is a multi species group not just 1 species

[GrnRunnin]

How are they supposed to find intelligent life on other planets when its so damn hard to find it on earth?

[Leviathan]

just because you cant see somthing...doesnt mean it isnt there!

[Fenrirwandering]

what if...we're the first! -(ominous music)-

[jehovasabettor]

Some thoughts on alien detection:
a) what makes us think we'd recognize an alien artifact if we found it under the bed? we don't really know what are we looking for in the first place, it could be something we're so used to we'd never think of it as alien, like white noise
b) judging from our own dead civilizations, how many of those left near no stuff behind, just because stuff deteriorates rapidly over time - and we don't have billion year old civilizations
c) our detection capabilities are low (no chance of spotting aliens suntanning on some distance planets), besides the further the object, the older is the info on it;
d) how would you prove, for instance, Jupiter ISN'T a slime-ball? its close, but hey, not as we could see through its atmosphere in any way

[hamstsorkxxor]

The only truly rational stance on this subject is to admit the obvious; no single absolute conclusion can be drawn, because we lack adequate data. We don't know, and we don't even know enough to constrain the problem in a quantifiable way.

[BasicShapes]

The Great Filter theory is interesting. I mean, if a society becomes technologically advanced enough to split the atom, but still firmly latches onto primitive notions of who's imaginary friend is you could argue that we're just very lucky we managed to send something out of our solar system before nuking ourselves to oblivion.