Meanwhile, there’s thousands and thousands of atom bombs waiting to go off…
I have to point out that the “simplest models about the Universe are wrong” is more than just a possibility, but such models are not considered valid by any of the modern theories. Those based on “The Big Bang” (perhaps some of the most credible, or at least, most widely subscribed to) have the amount of matter/energy present in the universe was set immediately after the BB and all that has been happening ever since is the energy/matter has been changing forms.
That is, there is a finite amount of matter/energy, not an infinite amount. Apparently a very large amount, but not infinite. Since we don’t know what the value of the non-zero possibility of life evolving is, there is no way to determine what amount of matter (or number of planets) would needed to even determine what the statistical probability of life evolving on another planet is > 50%.
When you understand that, then to continue to believe that life evolving on another planet is a certainty then yes, the argument can only be “Well, it’s just gotta be so”. If you don’t understand that, then you are in the same boat as someone who says “if it isn’t in the Bible, than I can’t believe it” coming from someone who hasn’t even read the Bible.
I don’t think anyone here has said that. They said if the universe is infinite (and, specifically, infinite in certain specific ways) then life elsewhere is certain. They didn’t say “life elsewhere is certain.”
Otherwise, we don’t know. There isn’t enough information. We know life arose once. We know the chemicals for life are present in the universe in large amounts. We know that other planets exist, some in the liquid-water zone around their stars. That all is highly suggestive. Nothing more: just…promising.
Moderator Warning
Since I’ve given instructions not once but twice to drop this line of discussion, I’m going to make this an official warning for failure to follow moderator instructions. If you want to pursue this debate, open another thread in Great Debates.
Colibri
General Questions Moderator
If you are going to take such an attitude, then do the right thing and move this thread to Great Debates and quit pretending that that there is a factual answer to a post which I have shown (as well as others) is more a matter of faith than one that has a factual answer, since there are no factual answers.
But we know for a fact that life developed once. So that eliminates the case that life is impossible. And once you know that life is possible, however unlikely it might be, you can apply that knowledge to the size of the universe. There are literally billions of galaxies and each one contains billions of stars. The idea that in all of those possibilities life arose exactly once seems ridiculous. Given the size of the universe, everything can be divided into two groups: the things that never happen and the things that happen a lot.
Moderator Note
If you wish to dispute my moderation of this thread, the proper place for that is ATMB. As other posters have indicated, this topic can be discussed in scientific terms. If you feel it can’t be, and you wish to pursue the discussion with regard to faith, as I said before you are welcome to open a new thread in Great Debates. Further hijacking of this topic may lead to additional warnings.
Colibri
General Questions Moderator
There are a couple of issues. First, how many stars have a planet in the Goldilocks zone (suitable for life to develop). Probably a lot, but we don’t know that. I keep reading things like, “Without Jupiter to mop up the asteroids, we would be under constant bombardment.” But of course, it might be (I am speculating here) that without Jupiter, there would be a planet in the asteroid zone. Then there is the question, assuming an earth-like planet in a habitable zone of a star not much larger than the sun (so that it doesn’t burn out too quickly) how likely is it that life would develop? From the one example we know, it happened pretty much as soon as conditions stabilized. But maybe that was simple luck and, on average, it takes 10 billion years. Then we can conclude only that we are on a planet that was lucky that way. Then once life developed, it remained prokaryotic for 2 billion years. That’s 40% of the time earth has been around. It could be that the average time for eukaryotes (cells with nuclei) to evolve was 20 billion years. Or 200 million. We just don’t know. If 20 billion, then the earth would have been long gone without developing intelligence. For eukaryotes to multi-cellular life seems to be nearly inevitable, so I will skip that. Now comes the million dollar question, intelligent life. Now intelligence seems to require hands. In 165 million years, the dinosaurs did not develop any technology. Neither have dolphins or elephants, no matter how intelligent they may be. The reason we have hands (skipping over a lot of detail) is that a certain group took to life in the trees. But for the most part, they ran along the branches. One minor group of them evolved brachiation somehow. The great apes are, I have read, the only animals that can hold their arms above their heads. Was this inevitable? I see no reason why. Then in parts of Africa, the trees disappeared and a small group of apes climbed back out of the trees. But they had partly adapted to vertical life and, for some reason, started walking on two feet. Freeing the hands for things like cracking nuts with rocks and, eventually, hacking meat off bones.
To me, this looks like an unlikely concatenation of fortunate circumstance. Sure if the universe (or multiverse) were big enough, it would repeated somewhere. But a more interesting question is whether it has happened in our galaxy. And there are too many uncertainties in all this for me to hazard a guess. I think the Drake equation is nonsense. Multiply seven quantities whose uncertainties might be orders of magnitude and expect to get anything useful.
I should add that distinguished paleontologist Simon Conway Morris believes that the evolution of human life was inevitable. But this belief is, for him, a matter of f…, oh I forgot we are not allowed that word on this thread.
Of course we should all bear in mind that when we look out into space, whether using light or radio waves, we are looking into the past. Alpha Centauri is 4.3 light years away and Hubble is ‘seeing’ stars 13 billion light years away, so anything we ‘see’ will be correspondingly old. For all we know there may be stuff going on now, but we won’t ‘see’ it for thousands of years.
I always found this interesting, if Alpha Centauri is 4.3 light years away, then that would mean it would take 4.3 years for light to reach Alpha Centauri from our Sun.
Transversely, it means that would take 4.3 years for light to reach earth from Alpha Centauri.
So my question is, how long does it take light to reflect off the moon’s surface and reach the earth?
But as far as extraterrestrial life? YouTube Video
This underlies some assumptions we have about the development of life that are chauvinistic toward carbon-based water-soluble molecules, i.e. we assume that extraterrestrial life will develop along the same lines that we have and require similar conditions. This is not necessarily, or even likely, the case. Without a body of data to assess, we just don’t know what conditions might be suitable to support self-organizing and self-replicating systems which regulate the flow of energy, which is our most comprehensive description of what life does. (That is to say, a system which does this might not necessarily be alive, but any system that is actually alive would satisfy this criteria.) Even if we do restrict our consideration of life to complex carbon chain organisms, there are conditions on the Jovian moon Europa and the Saturnian moon Titan (which we know has the precursors for complex organic molecules) which could potentially support the development of life. And of course, we have zero actual knowledge or experience with any other matrix which could potentially support a self-replicating stable organism. “Life” could potentially be a configuration of dynamically stable electromagnetic fields in a stellar atmosphere, or which uses hydrofluoric acid instead of water as a universal solvent, or any other configuration which could be potentially stable in the correct medium.
Actually, this is not at all inevitable, and indeed the manner in which life evolved form single cell eukaryotes to multi-cellular colonies of different but interdependent organisms to differentiated cells forming a single discrete organism is not at all clear and an area of major research. Similarly, the division of species into sexually differentiated forms, which allowed a massive increase in the variability and diversity of species, is an almost complete unknown and appears to be nearly impossible by the current understanding of molecular biology, and yet, it clearly happened at least once (that we know of…it appears that all sexually reproducing species are derived from a common ancestor, and complex non-sexually differentiated species are degenerate from former sexually reproducing organisms). These bottlenecks may be the true difficulty with evolving higher complexity and conceptual intelligence. Or they may not be; it may be that with the practically infinite number of possible permutations which occur with any sufficiently prolific form of life that such stages or analogues to them will appear almost inevitably. We just don’t have the empirical data nor sufficiently detailed predictive models to make even a qualitative statement one way or the other.
This is a demonstrably untrue factoid. Hell, a cat can raise it’s forearms above its head when rearing, and it isn’t even a biped. “Think before you ask these questions, Mitch. Twenty points higher than me? Thinks a big guy like that can wear your clothes?”
Stranger
Light travels approximately 182,000 miles per second. Therefore you can calculate the time it takes for light to reach an object, just by dividing the distance by 182000.
The moon averages a distance of 238,900 miles. Therefore light needs 238900/182000 or 1.3 seconds to travel from the moon to the earth, and vice versa.
The sun is at an average distance of 92,000,000 miles. Therefore light takes 92000000/182000 or 511 seconds to reach us.
Alpha Centauri is about 142000000 seconds away. Hubble sees 4300000000000000000 seconds away The universe is a startlingly huge place. No wonder we don’t get many visitors.
One of the major uncertainties in the Drake equation is that we only have a single example of a planet that has evolved life. Discovering even one more independent example in our solar system, especially under dramatically different conditions than on Earth, would help give us some idea of how likely the origin of life is.
Most organisms, from bacteria on up, have some method of transferring genetic material between individuals and thus promoting variability even if there is no differentiation between what might be considered sexes. In fact, horizontal gene transfer between very different procaryotic lineages is quite common.
I’m a bit mystified by your statement that “all sexually reproducing species are derived from a common ancestor,” and that the evolution of sexuality is “nearly impossible by the current understanding of molecular biology.” There is a huge diversity of sexual systems even within eucaryotes. Fungi for example have no sexual differentiation but often reproduce sexually, and some may have thousands of different mating types.
Can you give a cite or explain what you mean by these statements?
1.Kinda just goofing around too but do find the topic interesting, yet as far as the universe being a huge place, one mind say that it’s size is relative. Oh, a little Einstein humor there. However, as far as visitors, I would theorize that has more to do with location, location, location. Even less theoretical humor there!
However, there are many that hold that there is just One Great Light in this solar system, and the rest of the celestial bodies are just shining off it’s luminosity.
But it does beg the question, did the fourth basic form of matter-plasma [ionized particles] evolve to give life to the solid, liquid and gas which forms the physical human body, or did the human body evolve to give life to the plasma?
Depends on whether they piss off billions of goat owners…
You misunderstand. All of the simplest models of the Universe are based on the Big Bang, since any model which is not must be far more complicated than those which are, in order to account for various observations. And of those models which are based on the Big Bang, the simplest ones all have the Universe as infinite. An infinite Universe containing an infinite amount of matter and energy is not at all, in any way, inconsistent with the Big Bang.
Now, one can also construct other models based on the Big Bang, and which are likewise consistent with all of our best observations, which are finite. Such models are generally only slightly more complicated than the infinite ones, and are taken quite seriously by professional cosmologists. And in such a model, it would indeed be possible (to say nothing of the likelihood) for us to be the only instance of intelligence or even of life in the entire Universe.
But the statement I made remains true: In all of the simplest models of the Universe, it is mathematically guaranteed that there is life and intelligence other than us.
Given that single celled life appeared on the earth almost as soon as it cooled enough to allow it, I suspect that single celled life is relatively common in the universe, and probably occurs anywhere that has the right conditions available. As for multi-cellular life that didn’t occur for another 1.6 Billion years, so it seems to be much less of a forgone conclusion and probably required a certain degree of luck. Given that we only have one example of it, and its existence is required under the anthropic hypothesis we have no way of knowing how rare it is. Moving from multi-cellular life to intelligent life is yet another great leap of unknown frequency. In fact we don’t even know long term whether intelligence is an evolutionary advantage or a dead end, (ask me again in a few million years).
For these reasons I suspect its pretty lonely out there, with at most a dozen or so isolated intelligent civilizations in our galaxy with no way to communicate with each other before their eventual extinction.
The fact that life exists on our planet is proof that life is possible on a host planet. If it’s possible, then it can happen at some point in time. If you expect humans, you’re probably going to be disappointed, as whatever life form existed on the host planet would have evolved relative to the conditions on that planet.
I can’t speak for the scientific community, but if there are aliens I don’t see why all of them would be so shy. In human culture it is common for people from more (medical and scientifically) advanced societies to make contact with tribal people. They will seek out the group, form bonds and try to help them with things like medicine, education, etc. Aliens have not done that with us, there have been no attempts to communicate with the masses on a large scale from what I can see.
Plus SETI hasn’t found any radio waves so far.
Personally, I tend to think once a society becomes technologically advanced they can count on virtual immortality. If species survive millions of years with no science or medicine, then a species that has these should survive far longer. Granted you also increase your chances of self destruction, but you also increase your ability to survive calamities.
I think you’re being overoptimistic, since we have no friggin idea how life arose on this planet in the first place. If we had a reasonable model we might be able to calculate the probabilities.
However, we do have a good idea how long it took, so if we assume Earth was typical (i.e., nothing terribly unusual happened, given the circumstances), we can make some guesses. Actually, the early onset of life on Earth leads us to suspect that origins isn’t enormously unlikely, since it happened within just a few hundred million years after things cooled down enough. But we can’t be confident in that suspicion, because of the anthropic principle. Say it was terribly terribly unlikely. On how many planets with intelligent life would that intelligent life detect itself? Pretty much, all of them … questioning its own beginnings might even be the acid test for “intelligent”.
My understanding is that the Urey experiment isn’t particularly revealing, because the assumptions about the conditions of the Earth at the time have changed dramatically since then. But your point is valid: it is a subject that can be discussed scientifically.
This does not follow. If the amount of matter and energy in the universe were infinite before (or during) the big bang, it would still be infinite. As I understand it, if it’s infinite now, it was then too. Infinity can’t be ruled out. The pendulum seems to swing every generation or so, whether more cosmologists prefer infinite or finite. I think the jury is out and will stay out for quite a while on this one.
For a very interesting take on this, read Nick Lane’s Power, Sex, and Suicide. He makes the argument that development of eucharyotes happened just once, and that it’s pretty inextricably linked to sexual reproduction. He says it’s a terribly unlikely event, despite the fact that we have a number of other cases where bacteria were symbiotically subsumed and converted into organelles (e.g., chloroplasts).