Musings on life outside our planet

Okay - now that it's pretty much common knowledge that there countless galaxies with countless stars with countless planets (and more being made as we speak as the universe expands) it's pretty much a given that with those odds, life exists elsewhere. You just can't beat one-in-infinity odds. One being Earth, infinity being.......the rest of the universe.
That said, why do we expect other intelligent beings to even be searching for other signs of life, or having developed technologies to do this? Maybe there are beings that are whip-smart, but don't have "human" emotions like ambition, curiosity, etc? These are after all side effects of our intelligent human brains. Not necessary by any means. Maybe there are other beings that don't care about life outside their own existence, and will never have the abstract reasoning to even consider it. Since there are countless directions evolution can take, what are the odds that any intelligent beings would be "on the same sheet of music" and have any desire to interact with other beings? We as a species only recently got to this level, and this represents a tiny fraction of life's entire existence. My point being just because we don't interact with them doesn't mean there isn't life out there, or maybe was but is not anymore, or isn't yet but soon will be. Maybe alien probes visited Earth billions of years ago and determined that our planet was lifeless - which it was, at that time.
So don't bank on getting visited, or visiting others - those particular odds are trillions to one at best, if for no other reason simple logistics and physics. Expound and discuss!

Maybe they're just like us. Maybe, depressingly, almost identical to us, development-wise. Maybe they've got combustion-propelled probes that have spent the last handful of decades trudging along in their home star systems, skimming the fart-atmospheres of gas giants while, back home, the natives squabble and murder each other over tribal god-images. Maybe they're even physiologically identical to humans in every way, but they're still living in mud huts. Intelligent life doesn't necessarily mean orders of magnitude more intelligent than humans.

Alien could mean anything from 'so different that their priorities are completely incomprehensible' or it could just mean "like from Milwaukee, plus a few billion light-years distance."

My gut feeling is that the galaxy is teeming with life, most of it single celled. If I had to take a guess I'd say there are probably no more than a handful of technological civilisations similar to Earth in the galaxy right now.

Probably true - but there are billions of galaxies. It sucks everything is so far away!

I think every evolved species in this universe who reaches sentience will have similar drives and ambitions as us, just based on the survival-of-the-fittest dynamic that drives the evolutionary process. They'll probably be part of an ecosystem with some amount of diversity, different species will invariably have to compete with one another, the lifeforms with the strongest/fastest/smartest characteristics will survive to produce offspring, and so on.

Even if their native ecosystem is less competitive than ours, just reaching the technological point of blasting out electromagnetic waves into space, I think, shows a certain amount of ambition.

I think we're going to find simple life (microbes, plants) basically everywhere it can exist. Life is a chemical process, and where that process can happen, sooner or later it will. (There's evidence it may have happened several times here on Earth!)

If technological civilizations DON'T last very long, we may be it (at least in this galaxy).

If technological civilizations DO endure, then any that are out there are much older than us (remember, we're a NEW technological civilization).

My best guess is that there are other technological civilizations in our galaxy--perhaps quite a few of them--but that interstellar travel is probably impossible, so we're not going to encounter each other in the flesh. Perhaps we will detect signals from other worlds, but my hunch is that will be as good as it gets. The separations are so large, we're never going to have conversations. Or, if we do, no one who is alive when the questions are sent out will be alive when the answers return.

My version of that is that life is probably pretty common, but intelligence (as in tool-using technological civilization building) is probably rare. Any intelligent civilizations out there are probably way more advanced than we are just by virtue of the odds and the age of the galaxy. Interstellar travel will ultimately prove to be nowhere near as difficult as our current science believes it to be and there are probably several civilizations spreading through the galaxy right now. There are also probably versions of Von Neumann machines roaming around. Our SETI program is likely to not find anything because using EM transmissions detectable over interstellar distances is probably a short-lived phase that civilizations go through before developing something better.

I've often wondered if life has ever managed to develop inside a sterile jar of food, only for no-one to ever realise.

Given how truly uexpectedly bizarre some of the alien solar systems discovered have turned out to be, no doubt some alien life will turn out to be as equally bizarre, if not moreso.

There may be forms of life in the universe to whom Earth is an inhospitable lifeless HELLHOLE, & always has been. A place INCAPABLE of ever having a biosphere! Or capable of having one! Of course the reverse may be, if not possibly, true(?) Think(ing) of Venus here(?).

And Titan. Methane based life that may exist there would no doubt view Earth as a world of steaming HOT lava & magma oceans, with clouds of gaseous magma, & poles of rock (ice, which fills the roll of stone on Titan). Earth wouldn't exactly be a garden spot for such organisms!

I think my refrigerator has spawned something unholy by the smell.

An inhosptiable lifeless HELLHOLE? But enough about Detroit, let's try to stay on task here please.

Life could be a lot different elsewhere. Predator/prey mechanics worked here, but then we're in an oxidative atmosphere and close enough to the parent star to wallow in plenty of energy to allow for that kind of energetic race.

Other worlds may be different. They may not even use DNA, but another replicatory mechanism.

Intelligence isn't a given either. On Earth it is an evolutionary mechanism that gave us an advantage, on other worlds possibly less so.

All we can say is that it'll probably be carbon based (carbon being the perfect element for catenation), although boron and silicon are candidates too (both would likely need reductive atmosphere)

As for contact, well...

I think physics probably dictates that life will occur in a fairly narrow range of circumstances. I don't think we'll see complex organisms living apart from liquid water. I don't think we'll find life--certainly not complex life--in places like Venus or in the atmospheres of gas giants.

I think aliens WILL have DNA, because they--like us--will be made of cells and this is probably the simplest (only?) means to encode genetic traits and for cells to replicate. Of course, their chromosomes will not share any sequences with ours and theirs may have proteins ours lack (and vice versa).

Will they have sexes? I tend to think so, though they may not be perfect analogs for our males and females. It's pretty certain that intelligent aliens will; it's difficult to see how asexual reproduction would lead to kind of dynamic evolution that produced us.

Technologically capable aliens will understand mathematics, and they'll reason much as we do, though their values could be shockingly different. I don't think we can assume bipedal, human-like creatures like in television sci-fi, but they probably won't be tiny insects or giants, either. In order to have technology, they will have to possess ways of communicating with one another and of manipulating their environment. They may "speak" and "hear," but we won't be able to make their sounds, nor they ours.

I think it likely that intelligent aliens will have come about through evolutionary processes similar to the ones that created us. Intelligence requires a lot of bodily resources, and is of little evolutionary value to top predators. Intelligent aliens are likely to have a history of avoiding predators, much like us with the lions in the savannahs of Africa.

Will they be aggressive? I can go either way. On the one hand, it seems hard to imagine a super-aggressive species surviving its nuclear/biological weapons age. On the other, they may have unified as a species before they developed the means to destroy themselves.

If they come--and I doubt they ever will--it probably will not be to steal our resources. If interstellar flight is even possible, the beings who develop it will probably have plentiful energy to play with; they can make whatever they want.

Good point on stealing our resources. Would you drive out into an unknown desert area hoping a gas station will be open when you hit empty? No doubt they aren't on a one-way trip.
Unless they are KAMIKAZE aliens!

Coming to an earthlike planet for resources is just silly. Anything you can find here you can get much more easily out in space - water from comets, metals from asteroids, energy from stars, etc. No one in the way and not much of a gravity well to lift it out of.

Space-faring aliens would be able to remotely learn all they needed to know about our world before they came here. We are a few years away from being able to do this with nearby star systems.

Imagine if life somehow developed in an oxygen free environment, how insanely dangerous our atmosphere would seem.

Wow. That's an extremely limited and pedestrian view.

Bailey's view is not opposed by any evidence. I happen to agree with it because our failure to detect evidence of extraterrestrial intelligence leads me to think technological civilizations are very rare and/or not long-lasting.

We may very well be it. Or our nearest technological neighbor may be 20,000 light years away. If that's the case, we are unlikely to ever make contact.

It's not confirmed by it, either. The fact that we have not detected extraterrestrial intelligence does not mean it's not out there.

In spite of my cynical nature, in this case I prefer to see the glass as half full.

This thread, as well as two millenia of scientific discovery, tend to prove the naysayers wrong.

Up to now we only know of one planet that has developed life, Earth.

Obviously that's a small sample size to extrapolate from, but if Earth happens to be a typical example then the following may be the case.

1. Life develops quickly where there are the resources to do so.

2. The transition from single-celled to multi-cellular life is hard. It took life on Earth billions of years to make that jump. There doesn't seem to be any biological or resources reason it couldn't have happened much earlier.

3. Intelligence is rare among species. On Earth we know of only one species who has developed the ability to create civilisation, and it's only among the last 50,000 years or so that humans have started to become dominant on Earth.

Let's be incredibly generous, and say that for another 50,000 years humanity can be classed as a technological civilisation similar to our current one. (Beyond that we'll either be gone, or so far beyond where we are now such comparison would be laughable)

Earth is 4.5 billion years old, and has had life for around 3.8 billion years. Multi-cellular life has been around for a quarter of that time. If we take 100,000 years as the total duration of human civilisation comparable to our present day, then that is just 1/45,000th of the total lifespan of the Earth. Or if we look at the history of life on Earth to date, it's 1/38,800th of the total time life has existed.

Estimates for the amount of time multi-cellular life has on Earth vary, but it seems certain that between 500 million to a billion years from now Earth life will be single celled again.

If you just assume that any planets we find are identical to Earth, and we come across random time samplings from all stages of planetary development, then most we find will be in the single celled phase, some will have complex life, and a tiny fraction will have civilisation.

That isn't to say that I don't think many of those planets will have developed civilisation in the past, or may develop it in the future, it's just that the odds of us observing them at the precise instant they are at our present day stage are unlikely.

Well said.

It could be the case that what happened on Earth is different than what would happen everywhere else, but why assume we're "special?"

It could also be the case that we're the FIRST technological civilization in this galaxy. After all, if technological life is inevitable, someone has to be first.

It could also be that there have been lots of technological civilizations in the past and that there will be many more in the future, but that we're the only ones at present.

Don't get me wrong: I WANT to see evidence of other civilizations. But, given the constraints imposed by what we DO know, it's looking pretty unlikely.

Well, firstly, the universe does not appear to be infinite and there certainly are not more galaxies being created as it expands. So we aren't dealing with the odds suggested in the OP.

I do agree that simple life is likely to be reasonably common. Intelligent life is likely to be rare, and that's partially based on our having found no evidence of it. Our concept of "intelligent" is constrained as well. A lot of people seem to expect a relatively human psychology.

But the "no evidence" isn't really a deal-breaker because of the incredible distances. Other plants probably don't have evidence of us either. And I agree the odds of intelligent species being even remotely like us as far as psychology/culture/history/etc. are slim to none since their evolutionary journey would be completely different.
Maybe no vertebrates, no eyesight, who knows? There are countless ways evolution could have played out here.

Anyway new galaxies are not being created further out in the distant universe? Why is this?

It strongly weighs against there being any intelligent life in "our neighbourhood". We have been searching quite thoroughly for radio signals and have found none. That would mean that if it exists, it's on average seperated by very large distances and therefore rare.

We can see galaxy creation as we look into distant space, but that's because we're also looking back in time. If the concept of "now" means anything, then it's very likely that there are no new galaxies being created "now" because there is no new matter available to form them.

But maybe there are intelligent species that don't send out any radio signals. I wouldn't call humans in the 18th Century any less intelligent than current humans. Or maybe they evolved a bit differently and their geniuses discovered and explored different things entirely. Our ideas might blow their minds, but theirs might do the same thing to us.

Oh, I don't know.....

http://en.wikipedia.org/wiki/Wow!_signal

This is KWOW comin' at you baby. K-WOW...the future of Rock n' Roll! 800 Gigawatts IN YOUR FACE!
Transzygotron 648 called in again - get a life 648! Just pullin' your chain dude! He wants to hear "Rocket Man" but first I wanna spin you this gem from Deep Purple!
Yeah kids, buckle up because we're gonna be.....Space Truckin'! Whoo-hoo!

That's making the hefty assumption that radio signals would be used. A planet that didn't support groundwave or skywave propagation of radio waves would be unlikely to use that technology and follow a different route. Hell, a civilisation practically next door could be pumping out a big hello in our direction, and the transmission being absorbed by metallic gases between us.

Technology is a reflection of environment just as much as anything else is, if atmospheric turbulance were pretty rough above a 100 meters we'd likely never have bothered with flight and invested in better water-based technology for example.