Here is the basics of an old metaphysical equation concerning life in the universe: (i am sure its incomplete or not completely accurate as to the equation specifics - i think its a million to the power of 10 when its done).
If 1 in a million stars have a planet than could support life &
If 1 in a million of planets that could support life does &
If 1 in a million planets with life has life evolved beyond micro-organisms &
If 1 in a million planets with evolved life have intelligent life &
If 1 in a million planets with intelligent life have discovered tool use &
If 1 in a million planets with tool using life forms have discovered technology &
If 1 in a million planets withg techologically advanced life have begun space faring......
then there must be a billion trillion of space faring life forms due the the enormous size of the universe.
The idea that any life we find will be feeble compared to our own is still humano-centric garbage undeserving of scientific merit. As is the old 80's theory that if any life ever visited earth it would be peaceful because only peaceful life could advance to that level of technology without killing themselves, which is purely anti-human but clearly humano-centric thinking. lets not even get started on the TERRIBLE story in the latest "Day the Earth Stood Still" movie. By Armok, we should rise up and slay hollywood just for thinking of making that ... that ... theres just not word enough for it. Wait, i got it! That utterly ELVEN movie!
edited: for spelling and removed potentially political thoughts.......
As it turns out about 1 in 2 stars has planets and a decent fraction of those systems will have a planet somewhat like Earth in terms of distance from the star and stuff like reasonable gravity and the elements that we know work for at least one form of life so far- and though the chances of having all three of those and a few other things that may be major factors (or may not) that's still looking like a lot better than one in a million.
The one in a million tool users progressing to high tech seems silly. It only took us a few thousand years after we got half decent at the growing food thing and it's not like many (one in a million?) would even have the chance of wiping themselves off the face of the, well, other-earth before they got to high tech. Best chance for that I can see would be an industrial revolution that set off some disastrous global warming but that's pretty far fetched.
The "feeble" life thing makes a bit more sense looking at two simple things: the amount of time life on our own planet was in such a phase and the number of civilizations that have contacted us. If there is a civ many thousands of years further along than us they totally skipped things like radio broadcasting, stopped using it so long ago that we've already stopped getting their transmissions before we had a chance to look, or they're damn far away from us. All three of these options are far fetched and even that last one leaves a pretty small margin of possible times.
So basically once we start visiting planets we're pretty much going to find the feeble type of life first. Any nearby life we wouldn't have met at our current tech is what the star trek folk would call an anomaly.
As for peaceful visits once you know that other stuff and have a bit of an idea of how material-expensive space travel is there's no reason to make war on a developing species. Most habitable worlds are just going to have dumpy little bacteria that might not even mind you being there or be a problem for you and comparing one of those worlds to one that's had so much of the material mined out and converted into so much garbage that you might think a new continent was forming out in he pacific ocean... well who the hell would bother
taking this away from us? It would just be so much more expensive (and "our population is growing out of control!!1!" isn't a reasonable problem because you'd have to basically exhaust the resources of a planet to haul the population off of it for just a few years so all you can get from that is not having to control your population for a short while.)
I believe some calculations put there like 15-16 thousand Civilizations out there.
Main issue is that they most likely are COMPLETELY alien, were not talking star trek aliens, were talking about eyes coming out of there mouth mounted testicles, they probably wouldn't even have feet, maybe not even mouths or even eyes. (Edit: Testicles are earthlike things aren't they? Remove them then.)
Not to mention Cultural differences... Oh gods the Christians would be horrified.
Even if they were able to get to earth, they'd be REALLY STUPID to make first contact.
I'd be within a year after first contact, at our current situation, we'd blow ourselves up.
If every alien species has managed to translate things like that first it would make sense why they steer clear of this rock.
Aliens also probably wouldn't have language
Eh, they could have language, just probably not as we know it.
They could but there's no reason to expect it anymore than to expect them to be bipedal
or to have "peds"
Fishapods, insects, and land squid all seem to have developed them fairly independently so that particular one is a fair assumption unless they're aquatic floaty types with nothing ever having thought to scuttle about on the bottom of their ocean-kadoodle.
The one thing Scifi keeps ignoring is just how huge and empty space is ...
Early on we basically got in the rut of imagining starship battles as being pretty much like WW2 naval battles with frigates all over the place with a ton of small manned fighters zipping about
Yes, there's well over 100 billion stars in this galaxy, and we know of at least 100 billion galaxies, so ... there is a chance there's life somewhere.
However the Sun is an exception: Most stars are binary systems, and stable orbits are unlikely near those.
We find it fairly often at relatively large distances from the stars but recently we found one pretty close to it's pair.
But it's really only about half that are binary.
Also the Sun is in a safe location, since it follows a galactic arm at some distance.
When you understand that the arms are not a physical cluster of material spinning about with the galaxy but rather a compression wave (and therefore brighter thanks to the birth of many short lived stars,) it seems obvious that most planets that have been around as long as ours should be behind an arm.
If we were in that arm where new suns are born and old suns explode every couple of 100k years, or close to the galactic center,
Ok, that one's fair. Middle of the arms is pretty much a good place to look. The scale we're talking there though is pretty big so we won't be having to worry about even having the option of sending whatever over to anything else for quite awhile.
we'd be more likely to be hit by supernova explosions, or have something heavy alter the orbits of the Sun's planets. Stars in a stable, safe location like ours are quite rare.
We've got a whole strip down the back-middle of our arm of the galaxy to look at for now.
(Also life can probably only exist near Sun-sized stars: Small stars like brown giants are too cold, big ones send too much dangerous radiation and don't live very long before exploding.)
Yes and no. The radiation from one star isn't any different from that of another except what color it is. Our ozone layer shields us from a lot of the stuff the sun sends out way and our magnetic field keeps the solar wind from ripping the atmosphere off of the planet.
Not all big stars explode. Lots still ultimately end up as slowly cooling balls of iron and/or lighter elements after they've puffed off the last of the gas they are going to.
What you got right is that larger stars don't last long enough for us to expect civilizations near them.
As for small stars they've technically got a whole lot longer for the chemistry of life to do it's thang so the only trouble there is getting a suitable planet for it that's close enough to have 3 states of water temperatures, though with how long some of those stars last materials with similar properties aside from having their tripoint at much much lower temperatures are worth considering even with the slower chemistry.
Also, to make life, one needs heavy elements. These did not exist in the early universe - after the big bang, there was only energy; when that cooled down, it became mostly matter and antimatter which made more energy; some particles remained -- Hydrogen and Helium.
And a dash of lithium but since you were complaining about supernovae being all over the place in the spiral arms this shouldn't be a problem since they disperse all manner of heavy elements with that characteristic bang.
In order for us (mostly carbon, with some oxygen and iron etc) to come around, the Hydrogen and Helium had to form stars, which then fused Hydrogen, ran out of hydrogen, burnt at hotter temperatures creating heavier elements up to iron, and exploded in supernovae creating elements heavier than iron, and forming new dust clouds.
This must have taken a while - supernovae need to build up and go boom (tens of million years only, for very heavy stars), the escaping material needs to form dust clouds, these need to form into new stars ... eventually you'll get dust that is rich enough in heavy stuff to make earth-like planets.
And with all of the space we're considering here there are undoubtedly places that became life-available earlier than the Sol system.
Scientists estimate this would take some 10 billion years.
If you're reading sensationalist reporting -_-;
Earth is like 3 billion years old, and the universe 13.8 billion years if I remember right -- that means the Sun is probably among the first suns to even have enough heavy matter to form an Earth.
Add about 1 billion to both of those.
Still, with the universe as huge as it is, it must have life somewhere.
The size is another problem: No information can go faster than the speed of Light ... and that has been very much proven in Physics. Travel to somewhere that's even a hundred thousand light years away is pretty much infeasible if you consider the lifespan of human civilizations ... the whole planet would need to cooperate just to send a handful of people away, to never hear of them again. Likely?
We've got numerous countries cooperating just to send some hunks of metal up into space and so far it looks like they'll keep working together at least until we get someone on Mars so sure, it's likely enough.
More likely though is that we'd send robots ahead of us, since they don't need that whole life support shabang. NASA has sent off lots of stuff that the people working there aren't still there for by the time they get where they're going so it wouldn't be that different.
And once some robots found a world we were welcome on or an unclaimed one we'd pretty much send a small population over there just because a lot of us are aware of how it's possible for everyone on a particular planet to die in a cosmological disaster and we're a bit nervous about keeping all our eggs in one basket.
Sorry I sound like such a pessimist.
It's ok. When nobody else has ideas grounded in reality you kind of have to.
Source for my badly documented rant above is in an excellent astronomy lecture series by an astronomy prof, in German, which covers, among other things, questions such as "how real is Star Trek?", "are there aliens?" etc.
http://www.br-online.de/br-alpha/alpha-centauri/alpha-centauri-harald-lesch-videothek-ID1207836664586.xml
I'm glad there was someone else in this thread who knew a little more about this stuff than what you pick up reading fiction but judging by what you got from it he's a little out of date.
Still puts you way ahead of the curve though.
You know what I like? There are 3 kinds of alien believers. Those who believe they will be nothing like us and those who believe they will be awkwardly similar.
Why can't they have 50 legs and 2 eyes? Or 50 eyes and 2 legs?
That's got everything to do with coordination. If you look at the region of our brain we use for one limb and then multiply that by fifty they'd basically have to carry around a brain as big as ours just to control their body as well as something with a much smaller brain. Now, the brain is a pretty hungry organ- ours just about eats up half of the calories we consume ('cept maybe for fatty fats,) and for animals that don't basically have guaranteed food that kind of thing is going to mean starvation if it doesn't pay for itself, and right between social behavior and art it almost never does (likewise the gap between being coordinated enough to win fights against rivals/your-dinner and being social is also a hard one to breach, but once something does they're extremely successful.)
Now, as for 50 eyes that's a bit different because it depends on the type of eye. 50 like what we have is going to be a problem but 50 small ones that add up to a similar surface area of the retina (or more specifically similar number of rods and cones,) would be pretty ok in terms of mental requirements, though if they can move them that does mean 50 time as many muscles for it so the requirements would be a bit higher.
In terms of material cost to grow them though it's probably not worth it because dividing the volume by 50 doesn't scale the surface area down the same way.
But then again I don't see what good more than 4 eyes does for spiders so I guess I don't really know how factors for multiplicitus eyes work anyway.
Also, to make life, one needs heavy elements. These did not exist in the early universe - after the big bang, there was only energy; when that cooled down, it became mostly matter and antimatter which made more energy; some particles remained -- Hydrogen and Helium.
In order for us (mostly carbon, with some oxygen and iron etc) to come around, the Hydrogen and Helium had to form stars, which then fused Hydrogen, ran out of hydrogen, burnt at hotter temperatures creating heavier elements up to iron, and exploded in supernovae creating elements heavier than iron, and forming new dust clouds.
This must have taken a while - supernovae need to build up and go boom (tens of million years only, for very heavy stars), the escaping material needs to form dust clouds, these need to form into new stars ... eventually you'll get dust that is rich enough in heavy stuff to make earth-like planets.
You post was very well written. However I have a question. Why do you think, that only Earth-like planets can support life? We don't know anything about other systems or galaxies at all. Our knowledge is very minimal in this case.
Mostly it comes down to water.
Water is made out of hydrogen and oxygen which are both very common thanks to stars and their fusion habits. There are other molecules that can serve the same chemical role but they are made out of relatively exotic materials or require extremely low temperatures (and as far as chemistry goes you can treat that like it's going in slow motion.)
We know that life can handle some pretty extreme situations but we don't know if it can develop in them from the start.
[Anyway, there must be billions of Earth-like planets in the various galaxies probably.]
Now yet another interesting fact: How is it possible that not a single alien civilization has visited our planet?
That's called the Fermi Paradox. The answer most people lean towards is that they nuke themselves.
Now, one world had to be the first one to develop a civilization like ours so that
could be Earth but as we gaze into the heavens time and time against we've found that our world is pretty average in every way we thought it special or unique. There's no real reason to think that we had the best conditions for developing a civilization (especially when you look at the super long periods of time where life didn't seem to develop very much until some catastrophe stirred things up and got the ball moving again,) so that's just kind of a technical possibility more than a likelihood.
Another idea is that life is too frail to make long trips through space (astronauts lose a lot of bone and muscle mass,) but this idea is getting a bit dated because we could make artificial gravity just by designing our space craft to spin (having a little station attached to a counterweight and having most of the ship shaped like a big doughnut are popular designs,) but in recent years we've learned a thing or two about development and found that the way our bodies measure the stress on our bones scales right down just fine so you could strap vibrating pads to your astronauts (and maybe to your lazy children as well for an even greater effect) and possibly eliminate the biological downfalls of zero G.
*I don't think a human trial of the vibration thing has been done yet but with my understanding of bone growth it oughtta work.
Probably there are lot of advanced alien civilizations in our galaxy, or in other galaxies.
Seems undoubtable that there should be in other galaxies but in our own we have to have been at least one of the very first for there not to be a civilization spread all over the place.
This means, that even they weren't able to solve the "huge distances between systems & galaxies" problem.
Robots can undoubtedly make trips that long and we'll be able to make them sophisticated enough that they could set up little colonies for themselves on various planets to launch more robots till they'd visited the whole galaxy in a measly couple million years. Practically the blink of an eye when you think about how many civilizations should have had the chance before us.
Interstellar travel? How do you do it? Foldspace engines. We just need a way to break reality and fix it once we're done.
Why does every alien civilization use lazorbeems? Why not a cluster bomb that explodes into 100 cluster bombs that each explode into 100 more cluster bombs that each have 100 nukes inside? It may not be practical, but it'd be fun.
But if there's a misfire w
In terms of effect that's not all that different from what they did in Ender's Game.
Any kind of structured communication is a language.
Well if you define language that way then sure
But if they communicate by say, pheromones, it would be nonsense to call it "language" in the sense that we have, which is sound-based and uses symbols (words) and grammar and is also hardwired into our brains (which is why kids acquire language but don't learn how to communicate via pheromones)
And if they were telepathic there would be no need for language; they'd just send ideas straight to each other and cut out the middleman.
Specially if they have abstract concepts, which aren't instinctual.
Abstract concepts can be instinctual
That would require a perfect psychic interface but if their biology was subject to even half as many options for defects and variation as ours you'd have to do a pretty hefty load of interpretation or they'd just have a lot of members they couldn't communicate with at all except with a translator conveniently in the middle of their two mental types, or possibly a chain of translators.
And if they were telepathic there would be no need for language; they'd just send ideas straight to each other and cut out the middleman.
Different parts of the universe do not have different laws of science. Nothing is born with telepathy, period.
If you had a magnetic version of what ants do that would be awfully close.
And they could even carry magnets around to allow them to lie to each other
(If I remember right, chemistry/physics says silicone life forms such as bacteria would be possible, but mating would take 10.000 years or more ...).
Well silicon cando the same chemical backflips as carbon, or just about anyway.
Problem is that the compounds silicon forms are all rocks instead of things like butter, cooking oil, and sugar.
Pheromones used to say "i'm hungry", "i'm afraid" or "this way to the lavatory" don't need a language. Using pheromones to describe how to build a bridge or to perform mathematics or to tell someone "I wouldn't want to go anywhere without my wonderful towel" would need a language.
I'm hungry-towel n_n
Small stars like brown dwarfs, hmm: Basically gas planets so huge they fired up nuclear fusion inside, but not a lot ... if I remember right, it's too cold around those. I think we'd need a sun larger than 1/2 solar mass or so
Why do people stick to this? If you want more warmth, choose a planet very close to a dim star. If you want it colder, choose one far away. The amount of energy received from a star is inversely proportional to a distance from it, squared.
WHAT? MATHS!?
There's a little limitation in what kinds of planets can form where and planets that would migrate in closer are a complicated enough ordeal that they'd be quite limited.
A long lasting species colonizing a planet near a small star seems like a bright idea though.
Scientific model shows that yellow dwarfs, of which there are approximately a gazillion*, possess a habitable band. They also have a predicted lifespan of around 100 billion years.
*not a real number.
"Habitable band" is just a zone of certain level of radiation flux. No reason why e.g. brown dwarfs shouldn't have one. Same with brighter stars, though of course their lifespan is limited, but then, we are happily assuming that life always needs as long a time to evolve as it did on Earth.(which might be, might be not)
The technical explanation most often left out is that for smaller stars the band becomes so narrow that you won't find a planet with a circular enough orbit to stay within it.
Think lower. 1/100000000000000000000000000000000000000000000 chance still results on a crapton of aliens.
Zeroes don't work that way bub.
There would only be about 100,000,000,000,000,000,000 non-binary stars in the observable universe. At your chance it would be a long shot to just get 1 instance of life in that.
It's not as much a question of how many life forms can be out there, as what is the density of star systems containing life. In other words, if it's too far, in another galaxy, or in this one but 10000 ly away it doesn't really matter.
Maybe our civilization lasts (by which I only mean doesn't collapse so hard we have to start over from scratch,) another two million years so we could have close relations with them for almost half of that.
You folks keep talking about a 'chance to for life to exist,' or a 'probability that life will form' but I see no possible way for anyone (aside from God) to possibly calculate or accurately quantify that. You don't even have a pool of 'existing life' (aside from ourselves) to choose or to construct models from. And, moreover, if you consider that most of the different types of life on this planet are unique, that throws another spin on the puzzle.
All the life on Earth is carbon based living in water and using some combination of DNA and RNA to record it's body plan. Almost everything uses the same 20ish amino acids and I don't think there's anything that deviates from the code by more than two of those.
But ya, we don't have a second source of life to look at so we can whittle away places based on the things we know about our own chemistry down to a point but after that it starts become less measurement and most estimate. If you go out and look at the primary sources for most of the estimates the people here are throwing out there's usually a maximum estimate that just shows how many options are left when we reach that uncertain step, a decent middle ground estimate, and then a pessimistic estimate.
One form of life on a planet might or might not work. But finding one form of life on a planet isn't very useful. If you want to get really accurate, what's the probability of finding TWO forms of life on the SAME planet?
Without extremely rapid chemistry it's unlikely because the first form of life to reach a stage where it makes more of itself is basically like going from snail speed to breaking the sound barrier. It gets everywhere it can go so quickly that it's hard to imagine life from a different set of chemical reactions popping up at the same time AND having such a defined body plan that the two wouldn't merge in the act of trying to eat each other (which technically amounts to just one life origin.)
This is, of course, using the evolutionary model. And if that's not enough, how about THREE forms of life? Now throw Earth into the model and see if it remains intact.
It's all good and fine to start with one form of life and then have it evolve into others, but then you have to take into account the probabilities involved with that. Namely, the probability of the life surviving whatever process is involved with changing into the other, the probability of the both forms being able to survive the crossover (and that one doesn't inadvertently extinct the other), the probability that the life in question even begins the process of changing.
I'm wordy enough as it is without running a genetics tutoring session so I'm just going to recommend that you visit wikipedia and read as many biology articles as you can stand...
Then you have to do that for each and every change.
I mean, comon, folks. You're talking about complex physical and chemical structures as if they pop out of thin air of their own accord. It doesn't work like that. As for relying on chance, I don't think there's a being somewhere in the universe sitting on a pedastle flipping a coin and saying to itself, to mutate or not to mutate, that is the question.
Well, someone's always gotta bring that into these topics on a forum
And I agree with Il Palazzo: If it's too far away, it might as well not exist (here here for the humanocentric point of view). That is, of course, provided it exists in the first place.
I'm gonna add another caveat to that: If it's a single celled organism it isn't worth anything. We've got plenty of those here on Earth.
We've got plenty of plants too but each new one might have something interesting to it that would, say, lead us to a cure for all cancer.
...I need to get some sleep so we'll see if the other 2/3rds of this thread has enough novel material for me to make another post this large tomorrow~
Author
Topic: Alien Civilizations - Galaxy has 'billions of Earths' (Read 21545 times)