Odds of intelligent life occuring?

[Brian37]

I've seen figures of 2 trillion galaxies.

Huh? Ok, here is what NASA has said. You are right. But, then again, this is what science always does, unlike religion, adapts when better data comes in. 

https://www.nasa.gov/feature/goddard/201...ly-thought

NASA article wrote: "This led to an estimate that the observable universe contained about 200 billion galaxies.

The new research shows that this estimate is at least 10 times too low."

Point is that the universe is full of all the same atoms regardless so the likelihood of life existing on other planets is a high probability, even if we found all the life in the universe it would still constitute the minority of planets. But yea, the universe is massive regardless.

[Anomalocaris]

Now I'm not going to let exact facts get in the way of what I'm thinking, but you'll get my general supposition.

1) The early earth has a massive collision with another huge arse planet thing. -extremely rare (considering the emptiness of space)
2) Somehow the earth was able to keep our huge arse "moon" (bigger than pluto!) into earth's orbit (extremely rare) (did our molten iron core help with the gravity needed?)
3) The iron core helped create a strong magnetosphere protecting future life from solar anhillation! (just made that bit up but it sounds reasonable )
4) The big moon's gravity affected the earth's tides substantially.
5) All this just happens to occur in a goldilocks zone. The rareness is even moar extremelier!
6) Big brothers in space (Jupiter, etc) help with deflecting incoming space junk from hitting the earth.
7) Chemistry + energy (the sun) + tidal forces + billions of years = microbial life (biology)
8) In a billion years of life + evolution = many millions of diverse life forming. (most extinct)
9) Only one species becomes intelligent in a billion years of nature rolling the dice. Another freak chance accident of evolution?

On their own, these events are very rare. To have them occur all together is fucking rare!
(I use "fucking" as a scientific term to get my point across, "fucking rare" is 1 to the power of Godzilla for the mathematicians here)

This is why I believe intelligent life is so ridiculously rare, it's practically a novelty of the universe.
So rare that 99.999% of all other intelligent life (I'm not saying there is any, please don't put words in my mouth!), won't ever contact any other life.

So yes theists, we are special! (but not in the way you guys think we are)

We underwent miraculous odds to get here so what do we do? Elect Trump in the position of the most powerful man in the known universe!@

   

Don't really have a point to make ... Just putting it out there.

We have a evolutionary tree sample of one. We know it is a tree, but vast majority of the branches are gone, and most of those remain unknown to us. We can't be entirely sure whether the tree truely has only one root system or several intermingled ones. We are not entirely sure just how many trunks it has ever had.

We are not sure if this is the only tree that ever germinated on earth or there were others.

We have no fricking clue how the tree would grow if planted in different soil.

We are not even that sure what the soil was like when our tree first germinated.

So let's not be so bold as to say some form of evolutionary trees leading to some form of intelligent life can only grow in environment and soil conditions we infer to have existed on earth.

[The Grand Nudger]

@OP.  

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I like to remind people that the odds of intelligent life occurring are unity, 1/1, it happened.  I know that the impulse behind the question (and it's many answers) accepts that but contends "some of this stuff was super rare though, right?".  Let's take a look.  It starts at the macro level.  

We're asked to imagine the vastness and emptiness of space.  It is vast, it is empty, except for those things it;s full of.  Galaxies.  Galaxies are filled with stars.  Stars, have solar systems.  Solar systems are not so vast, and far from empty.  Collisions inside the gravity well of a star appear to be routine.  Our moon, which we're coming around to shortly, is evidence of that.  Stepping back out, our galaxy appears to be on a collision course with another galaxy, itself.  I suspect that when this course reaches it's terminus there will be a hell of a lot of collisions.  In summary, it doesn't appear to matter what level of granularity you assess the universe.  Collisions happen, and the more local the granularity the more frequent they appear to and must necessarily be.  

Ah, the moon.  Fun fact, it's escaping.  It's apoapsis increases by roughly 3.8cm every year.  The current theory is that a massive collision with a proto-planet either sheered it loose, or dove into our core expelling detritus opposite it's impact and just generally in a local wave of mass destruction.  The question in parenthesis at the end is a misplacement of wonder.  Planets of our size and composition fall into the solar orbits that they are in precisely due to their size and composition.  If we were going to get hit by a mars sized object with comparable density and comp to earth, "earth's lane" on the solar freeway is -exactly- where you'd expect that to occur.  We'll discuss that lane and the moon, again, shortly.

The convective rise and fall of heating and cooling iron, as well as whirlpools caused by coriolis generates the electrical current of the magnetosphere.   Yes, the magnetosphere deflects some UV radiation..but what gets through is still a lethal dose.  The earliest life put a more effective barrier between themselves and the sun.  Water.  The magnetosphere itself isn't a rarity, nor is it's interaction with uv radiation.  This inevitability is borne out by the laws which govern where in the orbit of the sun a planet with an iron core will form, by what will happen when iron is subjected to heat, pressure, and rotation, and by the manner in which that active iron core produces energy.  It's as common as any electromagnetic coil working.  

Ah, the tide.  The moon, initially, would have had a catastrophic effect.  Magma tides more like tsunamis than highs and lows - there wouldn't exactly have been alot of water vapor on earth post collision.  Tidal earthquakes on a clock.   We sometimes forget the devastation that tides cause today, as well...then hurricane season hits and we remember.  Far from being the peaceful benefactor of earthly life, the moon was once an even more effective agent of annihilation than it is today.  It's a good thing that our genetic lineage wasn't around then, or for ages thereafter.  One day, it's going to completely halt our rotation.  One side of earth will be permanently fixed facing the moon...as the moon faces us.  Life as we know it on earth will have been exterminated long before that work is done.  Then, it will leave.

Now we're back in-lane.  The Goldilocks Zone.  It sounds small, like a little girl..and we all know the story.  However, the character of the story and it;s narrative thrust have little, if any, resemblance to the usage of the term in astronomy.  The HZ (habitable zone) at this point in time for a star like ours is at least .7AU wide.  This doesn't properly account for extremophiles and certainly doesn't account for novel exo-geology.  It's 70m miles wide.  You could fit 9k earths shoulder to shoulder within it's inner and outer boundaries....and we're drifting at the outer edge of it.  No point on that line is "just right" unless our tolerance for error is big enough to drive a star 9x the size of our own through.  

Speaking of shooting the gaps, other orbital bodies do take some hits for us.  The moon is famously pockmarked.  They also pull those objects shooting the gaps into eventual collision courses with us.  It seems, as we discussed before...that at least once those other planets -were- the things crashing into us, and none of them seemed to keen to take one for the dinosaurs.  

Chemistry+Energy+Tidal forces+Time=Life sounds more like an invocation of inevitability.  May not have needed the tidal forces, either...but at present it seems likely, at least.  That's pretty much the only thing in that equation that could have gone another way.  I say "could have" ignoring for purposes of discussion that...in this solar system...it couldn't have gone any other way.  If there was a rock like ours formed in our band on a collision course with us, and that collision was going to carry x amount of force - then the moon and all of it's attendant effects were a predictable result waiting to happen.  Chemistry, energy, and time aren't variables in this equation. The sun existed. Earth had a chemistry. Time was on the march.  

Evolution is certain when errors in reproduction occur.  It's not strange or odd or unlikely that, after billions of years, the accumulated differences of many billions of generations produce a vast array of forms.  As to the ratio of living to dead....well, wouldn't that be expected as well?  No day on earth is exactly like the last - and we've had many billions of those in the same time, with similar accumulated differences.  

Now, about intelligence.  This one is flat out wrong.  We're far from the only example of intelligent life.  -Plants- are intelligent.  The entire kingdom of animalia is intelligent. I suppose there being little more to say on this one it;s a great time for summary.   The chances of life occurring are unity.  A known event that happened.  It happened on a planet whose composition and density could support life, where other such planets could (and apparently did) form.  A planet that is, like every other planet, the sole survivor of a cosmic game of road rage.  A planet that, like the others, has an orbital body.  A planet that sits within a range of potential habitation as wide as an astronomical unit as, potentially, 40b others outside of our solar system do.  On a planet where the collisions are infrequent but still deleterious.  A planet which only needed what was present in order to produce life in what was, referencing the age of our planet - a short timescale.  A planet which now teems with intelligent life.  The mind numbing commonality of it all is what strikes me, personally.  

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TLDR version: Sure.  I guess we're special....at least in the same way that everyone else is special.  We're all a bunch of intergalactic snowflakes.  

[Gawdzilla Sama]

The question is, did it happen elsewhere? We simply can't say.

[drfuzzy]

Just simple musings, but I think that life is probably abundant.  Intelligent life, however . . . of the sort that alters its environment, uses tools, and makes it out into space . . . now that is probably a bit more rare.
  
This guess is simply because most of the organisms we see on our planet are uniquely suited to their environment.  When the environment undergoes a drastic change - the species goes extinct.  So you would need a creature able to recognize that danger and adapt.  You would need a creature capable of manipulating its environment to insure its own survival. You would almost certainly need a creature capable of working as a group - - although this could be commonplace.  You would probably need an "underdog" -- a prey animal who had to develop weapons and various forms of protection to survive.  It would need to develop the ability to think in the abstract, and the ability to imagine, to think in terms of future events.  And you would need a creature that was curious, driven to explore.  

Homo Sapiens (and Neanderthals and others) are unique partially because they fought for their own survival against the environment and against predators.  We accomplished this be creating tools and shelters that helped us survive, and in those acts of creation, we created ourselves.

[Astreja]

I believe that due to the size of the universe, the prevalence of the key elements (H, C, N, O) required for organic chemistry and the age of the universe, life elsewhere is virtually inevitable.

However, because of the vast interstellar distances I think it unlikely that we will be able to communicate with intelligent life from distant worlds. As things currently stand, I can see only one-way communications received many years later, and not a dialogue.

[Gawdzilla Sama]

Live existed on Earth for a long time before intelligent life came around. This leads me to believe it would be rather rare.

[The Grand Nudger]

Half a billion years doesn't seem like much to me.  From the formation of earth to the emergence of intelligent life there was only 1b.  Half of that is the time it took for life to arise in the first place. It's our strange views on intelligence and "a long time"(and what either means) that leads people to conclusions of arduous rarity.

Since then, enough time has elapsed for life to have evolved intelligence 8 times over, just on this..relatively young, rock.  No more than 20m years after the big bang the oldest rocks would have had the potential for habitability.  On those rocks, enough time has elapsed since then for life to have evolved intelligence 29 times over.

Taking a more dim view, as intelligent life being ourselves and ourselves alone - then enough time has elapsed since the big bang for life like ours to have evolved at least three times over. In all of that time it's had no shortage of candidate rocks. Using the figure I leveraged earlier, of 40 billion potentially habitable planets - that gives us very nearly three potential startups for life ever single year just to fill the time averaged out.

I'd say that something which at least -could- have happened three times every year since the big bang is hardly a rarity. It would be something which at least -could- have reached terminus (life like ours) once every four months past 4.5b years. I suppose it's just a matter of perspective. So far, we've found life exactly where we expect to find it. 1 for 1....and we're starting to suspect that life may be able to exceed those boundaries...the tolerance is likely to go up, not down. The numbers will become more amenable to life (and they're already pretty damned amenable).

[Catholic_Lady]

I do agree that intelligent life is extraordinarily rare. But I also believe the universe is so huge, that there MUST be other intelligent life out there, regardless of how rare it is. But yeah, I highly highly doubt any intelligent life will ever come into contact with other intelligent life because of how rare it is and because of how huge the universe is.

[Whateverist]

I suspect that the formation of life under the right circumstances is probably just about as certain as the formation of rust under its necessary conditions.  Naturally occurring disparities in the cognitive ability of species to interpret and respond to what is happening in its environment, would always result in the selection of the fittest.  

I think the jump in intelligence which interests us most is that which allows an organism to adapt to its environment through radically modifying its own behavior on an individual basis.  That may not be inevitable.  Here on earth we have colony animals whose success is predicated on the behavior of the individual being subsumed by the requirements of the colony.  Varying strategies can win the day (and the niche).  Our own style of success seems special to us because it is so familiar and, lets face it, we have a stake in the outcome.  But there is no objective scale of intelligence with places our way of doing it at the top.