# Are we alone? **URL:** \ **Category:** Great Debates\ **Created:** [May 6, 2011, 5:07pm UTC](https://boards.straightdope.com/t/are-we-alone/580981 "2011-05-06T17:07:47Z")\ **Posts on this page:** 20\ **Page:** 4
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [May 9, 2011, 5:21am UTC](https://boards.straightdope.com/t/are-we-alone/580981/61 "2011-05-09T05:21:51Z")
> [@Naxos](#): > > That’s wrong. > > Anything we observe or can comprehend, is just one sample of many other objects that have the same exact properties. No, that’s wrong. Almost anything we observe or can comprehend is a unique example, and no other objects have the same exact properties. ---
**Author:** ![Naxos](https://avatars.discourse-cdn.com/v4/letter/n/50afbb/32.png) [@Naxos](https://boards.straightdope.com/u/Naxos)\ **Post date:** [May 9, 2011, 6:43am UTC](https://boards.straightdope.com/t/are-we-alone/580981/62 "2011-05-09T06:43:15Z")
> [@Blake](#): > > No, that’s wrong. > > Almost anything we observe or can comprehend is a unique example, and no other objects have the same exact properties. We can observe, analyze and comprehend a tree (not at 100% yet, but close enough). There is no unique tree in existence. As there is no unique object existence about anything we can comprehend, humans included. ---
**Author:** ![even\_sven](https://avatars.discourse-cdn.com/v4/letter/e/dfb087/32.png) [@even\_sven](https://boards.straightdope.com/u/even_sven)\ **Post date:** [May 9, 2011, 7:43am UTC](https://boards.straightdope.com/t/are-we-alone/580981/63 "2011-05-09T07:43:43Z")
I have no idea if we are alone or not, but I don’t understand how the question can be anything more than idle curiosity. If we are, in fact, alone, we will never be able to actually prove it. If we are not alone, experience shows that we are nowhere close to knowing and are not going to actually be able to use that information in any way any time soon. So we have an unanswerable question that has no effect on our lives. It frankly does not matter what the “truth” is n ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [May 9, 2011, 8:04am UTC](https://boards.straightdope.com/t/are-we-alone/580981/64 "2011-05-09T08:04:08Z")
> [@Naxos](#): > > We can observe, analyze and comprehend a tree (not at 100% yet, but close enough). No, we can not. > [@](#): > > There is no unique tree in existence. Every tree in existence is unique. ---
**Author:** ![mac\_bolan00](https://avatars.discourse-cdn.com/v4/letter/m/b3f665/32.png) [@mac\_bolan00](https://boards.straightdope.com/u/mac_bolan00)\ **Post date:** [May 9, 2011, 8:24am UTC](https://boards.straightdope.com/t/are-we-alone/580981/65 "2011-05-09T08:24:36Z")
> [@FarmerChuck](#): > > Are we alone? i think if a rational person looks at carl segans formual ud have to be an idiot not to agree that no we are not alone.. and when i bring this up in casual conversation im the “crazy” one… are we so egotisical and dumb to think that we are it??? also the universe (we think) is expanding.. soo wouldnt the planets/galaxies farther out then us be more advanced b/c they have had thousands if not millions of more years to start off? so surley they must have the technology to see us right? > So what gives ? (aliens if your out there and can somehow see this you all suck, let us into the “club” ) estimates of possible life-sustaining planets out there range from a few million to 65 billion (the last one is a dubious estimate from a dubious site.) > [@](#): > > Does anyone believe in the following ? > > 1. mayains/egyptians/ etc have help? building stuff like the pyrimids, or was it just alot of slaves… and even still who gave them the designs to build that way back then why are they prefectly inline with celesital objects? why did ancient people have physical god like powers? (lightning bolts=lazers?) the 5-sided pyramid (include the square base) is a naturally occuring shape. in the days of contruction of non- load-bearing structures, the pyramid was a logical choice since it was more stable, and entailed fewer tonnage of material moved as one went higher. don’t under-estimate human resourcefulness. > [@](#): > > 1. If we didnt have the “dark feudal ages” for 800 years when science was “the devil” would we be talking about this from the moons of endor? i mean think what if we had comptuers in 1250 ad? not 1950 ad … interesting question. could the industrial revolution have occurred 600 years earlier? you have to consider what happened before victorian england. you’ve had at least one major reformation of the catholic church, at least one rebirth of classical art and philosophy, one science revolution (invention of calculus and analytic geometry,) various discoveries for physics, chemistry and medicine. > [@](#): > > 1. Have aliens visited us? i think so i mean if there is an advanced civilization out there somewhere watching us… (there has to be) and they start recoreding nuclear bombs going off dont u think ud pop in for an look see? can’t answer that one. theirs would have been a technology that defies our own and even our senses. > [@](#): > > 1. when world war 2 broke out.. .how did the nazis suddenly get almost stealth tech, and rockets… and we got the A bomb… also when we started nuking stuff thats when roswell happend… could the thing that crashed have been a probe? i dont see why not… and then suddenly things started to get really advanced nothing the allies didn’t have as well. > [@](#): > > 1. why do the governments of the world keep stuff from us? i mean if we found out we were not alone are they afraid what would happen to society? i mean that would kinda shoot most religon right out the window > 2. why did we stop after getting to the moon, why has every other country not really tried? can’t answer you but it hardly has a bearing on your question (does it?) > [@](#): > > 1. are we going to be on this rock forever? why is going farther not a national debate i mean where is the christopher columbus of our day? it makes no since to me that a nation and people here b/c of exploration have stoped… even the SETI mission has ended that the one where they look for extra territrial life… did they find something? i can see how it could really screw up tyhe power balance i mean maybe the aliens told us back in the day, we will come to you when your a unified government, when we are sure that you wont use our technology to kill yourselves over land/power/resources Could we be under some sort of prime directive? > > Am i alone? probably not. ---
**Author:** ![Farmer\_Jane](https://avatars.discourse-cdn.com/v4/letter/f/bbe5ce/32.png) [@Farmer\_Jane](https://boards.straightdope.com/u/Farmer_Jane)\ **Post date:** [May 9, 2011, 9:15am UTC](https://boards.straightdope.com/t/are-we-alone/580981/66 "2011-05-09T09:15:02Z")
I kind of think that aliens and time travel (yeah, you can rolleyes at me) could be part of the same idea. Who’s to say someone from the future didn’t travel back in time to the pyramids and show the Egyptians something? That blows my brain less than someone four thousand light years away being as evolved -or better- than we are.\* [faster than the speed of light? be still.](http://news.discovery.com/space/warp-drive-spaceship-engine.html) \*Understanding that not all factors will stay constant ---
**Author:** ![Voyager](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voyager/32/133_2.png) [@Voyager](https://boards.straightdope.com/u/Voyager)\ **Post date:** [May 9, 2011, 4:52pm UTC](https://boards.straightdope.com/t/are-we-alone/580981/67 "2011-05-09T16:52:13Z")
> [@Blake](#): > > As I said clearly, it’s an estimate. > > You are now invoking the anthropic principle. > > If the Earth did not exist, how could we be discussing this? So clearly the existence of the Earth is a precondition for the existence of this discussion, and therefore can not be used as evidence for any position \*within \*the discussion. We do know that the probability of life existing is \> 0. That is evidence. Now, as to how far beyond zero that is, it is surely higher given that we know of intermediate stages between life and non-life (viruses, prions) as opposed to the simplest entity being a cell. ---
**Author:** ![Paranoid\_Randroid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/paranoid_randroid/32/18_2.png) [@Paranoid\_Randroid](https://boards.straightdope.com/u/Paranoid_Randroid)\ **Post date:** [May 9, 2011, 5:24pm UTC](https://boards.straightdope.com/t/are-we-alone/580981/68 "2011-05-09T17:24:19Z")
> [@Naxos](#): > > There is no unique tree in existence. Assume that there is no unique tree. Thus for every tree, there is at least one other tree for which every property that is true of the first tree is true of the second tree. Because differentiating between the two trees is impossible, there is no way to decide whether there is more than one tree. “There is no unique tree in existence” is thus not a statement amenable to science. ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [May 9, 2011, 6:26pm UTC](https://boards.straightdope.com/t/are-we-alone/580981/69 "2011-05-09T18:26:03Z")
> [@Voyager](#): > > We do know that the probability of life existing is \> 0. That is evidence. Now, as to how far beyond zero that is, it is surely higher given that we know of intermediate stages between life and non-life (viruses, prions) as opposed to the simplest entity being a cell. Right. We know the probability of life arising is greater than 0. But it could be 1 in 10^10000000000. If it were that low, we’d probably be the only life in our observable universe. The problem is that we have exactly one sample, which seems like a lot of information. But if that sample didn’t exist, we wouldn’t be here to observe the sample. So that proves that our sample is a biased sample. So the sensible thing to do is to throw out this sample, since we know it is biased. However, if we throw out this sample, we have no other samples left, which is hard to take. It seems to me that we could within a few decades find evidence for life on extrasolar planets if we find spectroscopic evidence of free oxygen or other molecules that are only produced by life. Or we could find evidence for life in our solar system. Then we’d have to figure out whether that life was closely related to earth life. It could be, for instance, that life first arose on Mars, and life on Earth is descended from Martian organisms that somehow managed to migrate to Earth. If that’s the case, then we don’t have multiple samples, only one sample, and so we’re back to square one. But if life on Europa was completely unrelated to life on Earth, then we have very strong evidence that life has a very strong probability of arising, and that a random solar system is very likely to have living organisms on one or more bodies. But this is all speculation. It seems to me that the speed at which life arose on Earth means that life should be fairly common. But we just don’t know. If you pointed a gun at my head and forced me to bet, I’d bet that life is pretty common. But because of the anthropic sampling bias, I have no way to know if that’s a good bet. ---
**Author:** ![Paranoid\_Randroid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/paranoid_randroid/32/18_2.png) [@Paranoid\_Randroid](https://boards.straightdope.com/u/Paranoid_Randroid)\ **Post date:** [May 9, 2011, 7:23pm UTC](https://boards.straightdope.com/t/are-we-alone/580981/70 "2011-05-09T19:23:13Z")
Perhaps someone could clarify what the word “probability” refers to in this scenario. My impression is that the discussion has centered on the probability that other intelligent life exists elsewhere in the universe, but this isn’t something to which an objective interpretation of probability can be meaningfully applied. Either there exists life elsewhere or there does not. We should instead like to quantify the degree of uncertainty attached to that proposition. With that in mind, I’m unsure what it even means to say that the earth composes our current sample. What _is_ a data point? A planet? A planetary system? A galaxy? Can we demonstrate the degree of comparability between data points – i.e., do we have any idea whether other planetary systems/stellar systems/galaxies are comparable to ours with respect to their suitability for life? Do we even know enough about how the _unique_ circumstances on earth contributed to the rise of intelligent life to make statements about how probable it was? ---
**Author:** ![Voyager](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voyager/32/133_2.png) [@Voyager](https://boards.straightdope.com/u/Voyager)\ **Post date:** [May 9, 2011, 8:20pm UTC](https://boards.straightdope.com/t/are-we-alone/580981/71 "2011-05-09T20:20:12Z")
> [@Lemur866](#): > > Right. We know the probability of life arising is greater than 0. But it could be 1 in 10^10000000000. If it were that low, we’d probably be the only life in our observable universe. > > The problem is that we have exactly one sample, which seems like a lot of information. But if that sample didn’t exist, we wouldn’t be here to observe the sample. So that proves that our sample is a biased sample. So the sensible thing to do is to throw out this sample, since we know it is biased. However, if we throw out this sample, we have no other samples left, which is hard to take. But we have more data right here than just that life exists. The thing that determines the probability of life beginning, at least partially, is the complexity of the simplest form of life or pre-life. Viruses seem to not be considered as truly alive, yet they evolve - they reproduce imperfectly and are subject to natural selection. Since we have already constructed working viruses in the lab, it can’t be that low a probability. Of course all existing viruses have evolved to be dependent on truly living things. Hell, a small bit of RNA wouldn’t. be that hard to make, and I assume there are simpler self-replicating molecules out there. We don’t know what p is exactly, but I think there is good reason to believe that it isn’t ll that small. ---
**Author:** ![sevenwood](https://avatars.discourse-cdn.com/v4/letter/s/6de8d8/32.png) [@sevenwood](https://boards.straightdope.com/u/sevenwood)\ **Post date:** [May 9, 2011, 8:22pm UTC](https://boards.straightdope.com/t/are-we-alone/580981/72 "2011-05-09T20:22:39Z")
> [@Blake](#): > > As I said clearly, it’s an estimate. Estimates are made with some reasoning behind them. Given that you have declined to produce any such reasoning, I’m going to have to assume that you just made up a couple of humongous numbers on the fly for which you are now attempting to evade any explanation. Seriously, how did you get those “estimates”? ---
**Author:** ![Voyager](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voyager/32/133_2.png) [@Voyager](https://boards.straightdope.com/u/Voyager)\ **Post date:** [May 9, 2011, 8:24pm UTC](https://boards.straightdope.com/t/are-we-alone/580981/73 "2011-05-09T20:24:34Z")
> [@Paranoid\_Randroid](#): > > Perhaps someone could clarify what the word “probability” refers to in this scenario. My impression is that the discussion has centered on the probability that other intelligent life exists elsewhere in the universe, but this isn’t something to which an objective interpretation of probability can be meaningfully applied. Either there exists life elsewhere or there does not. We should instead like to quantify the degree of uncertainty attached to that proposition. > > With that in mind, I’m unsure what it even means to say that the earth composes our current sample. What _is_ a data point? A planet? A planetary system? A galaxy? Can we demonstrate the degree of comparability between data points – i.e., do we have any idea whether other planetary systems/stellar systems/galaxies are comparable to ours with respect to their suitability for life? Do we even know enough about how the _unique_ circumstances on earth contributed to the rise of intelligent life to make statements about how probable it was? The Drake equation is inherently probabilistic. That 50% of stars have planets says nothing absolute about whether any of them have life, but this is certainly more likely than if 1% of stars have planets. I assume someone has adapted the Drake equation to cover the probability that intelligent life exists within a certain radius of earth. Not hard to do - the number of stars is much reduced, and the ratio of stars with planets might differ from the universal case since stellar population near us is probably skewed in some way. Clearly the smaller the radius the less likely it is that we find life. ---
**Author:** ![sleestak](https://avatars.discourse-cdn.com/v4/letter/s/919ad9/32.png) [@sleestak](https://boards.straightdope.com/u/sleestak)\ **Post date:** [May 9, 2011, 10:38pm UTC](https://boards.straightdope.com/t/are-we-alone/580981/74 "2011-05-09T22:38:25Z")
> [@Voyager](#): > > There are plenty of reasons for advanced cultures to not contact us even if they could. Given what happened on Earth when “advanced” cultures contact less advanced ones, any ethical race would stay far away until we matured a bit more. Perhaps when we reach Alpha Centauri we’ll find them there to greet us- not because they live there, but because we passed a test. Just gotta comment on this. There is no reason to assume that any intelligent race that may exist would have any idea of ethics, much less ethics that mirrors our own. Heck, I’d bet that there are a fair number of humans who, if we located an alien intelligent race, would be all for killing 'em all and taking all their loot (if we could do it). It’d be nice to think that the Star Trek non-interference ideal is universally held but since we can’t even agree on that ourselves it doesn’t make any sense to assume any other intelligent life forms would follow it. It’d be nice if the aliens, assuming they exist, are all bunnies and kindness (especially if there are hot alien chicks in bunny suits) but intelligence and tech does not require \*our \*moral code. Slee ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [May 9, 2011, 10:40pm UTC](https://boards.straightdope.com/t/are-we-alone/580981/75 "2011-05-09T22:40:41Z")
Viruses are probably not very much like the first protolife, because viruses are obligate parasites on existing cells. So viruses couldn’t arise and evolve until after cells existed. Now that we have detected extrasolar planets, it seems clear that any given star is likely to have dozens of objects orbiting around it. Back in the old days there were theories that planets were formed by extremely rare stellar near-collisions. If that were true, then there could be a 100 million stars in the galaxy but only thousands of planets. It was considered a Big Deal when they first discovered that pulsar had bodies orbiting it. Yeah, most people thought that planets would be common, but no one knew for sure. ---
**Author:** ![Superfluous\_Parentheses](https://avatars.discourse-cdn.com/v4/letter/s/8edcca/32.png) [@Superfluous\_Parentheses](https://boards.straightdope.com/u/Superfluous_Parentheses)\ **Post date:** [May 10, 2011, 12:20am UTC](https://boards.straightdope.com/t/are-we-alone/580981/76 "2011-05-10T00:20:30Z")
> [@Max\_the\_Immortal](#): > > Most right-thinking people wouldn’t dismiss out of hand the notion that at one point, billions of years ago, the sum total of life on Earth was a small collections of crude single-celled organisms that could fit into a teaspoon as easily as you or I could fit into a football stadium. But the Earth was so _huge_, it would have been an awful waste of space to have a teaspoon of life on an otherwise barren rock, right? Fast forward to today. The globe is absolutely infested with living things. You can’t inhale without sucking in a bunch of spores. And it call came from the Primordial Ooze. It’s remarkable, really. > > Suppose that the rest of the universe is barren. That the sum total of life in the universe can fit onto a single planet as easily as you or I could fit into a football stadium. Suppose that, billions of years in the future, the universe is infested with life descended from the life on Earth today (whether spread by people deliberately setting up colonies or by [more ignoble means](http://www.youtube.com/watch?v=kndxsByVscA&t=160)). Could people living in that future find is as plausible that all life in the universe originated from a single planet as we can find it plausible that all life on Earth originated from a microscopic clump of bacteria? > > Now, ask yourself which is a more egotistical attitude: > A) That we are so close to the pinnacle of the complexity of life that all across the universe billions upon billions of planets have independently given rise to organisms that, all things considered, are pretty much just like us? > Or B) That in the grand scheme of things, we aren’t that far removed from the Primordial Ooze? I think this is a pretty interesting argument. But I don’t agree. Couple of reasons: - The general principle that whatever we see all around us is not all that special, especially that most times we had the idea that we (humans, mammals, animals, life, earth, the sun, the milky way, whatever) are extremely rare or special it’s been proven to be mistaken. - I do not think that life is “pretty much like us” even here on earth. Life on earth is amazingly complex chemistry and it would be folly to think we could predict what life anywhere else would be like. Though it’s probably a good guess that it would employ most of the more chemically active common elements in the universe. Just like we do. Both seem to me to point to abiogenesis events not being so uncommon to make us (that is us, the life on earth) the first ever. It’s possible, but even if true, it won’t rule out us meeting alien life some time in the future. ---
**Author:** ![Farmer\_Jane](https://avatars.discourse-cdn.com/v4/letter/f/bbe5ce/32.png) [@Farmer\_Jane](https://boards.straightdope.com/u/Farmer_Jane)\ **Post date:** [May 10, 2011, 12:35am UTC](https://boards.straightdope.com/t/are-we-alone/580981/77 "2011-05-10T00:35:17Z")
> [@alphaboi867](#): > > So is the whole “the pyramids were build by slaves”. The pyramids were public works projects designed to keep pheasants busy during the off season when the Nile flooded. For millenia people just assumed that slave labor was used since no could imagine large numbers of free men voluntarily signing on to do that much risky and back breaking labor. We since found surviving employment contracts were they agreed to do just that. I’ve never heard that the Hebrews built the pyramids. Weren’t they in existence already? ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [May 10, 2011, 3:11am UTC](https://boards.straightdope.com/t/are-we-alone/580981/78 "2011-05-10T03:11:31Z")
> [@Voyager](#): > > We do know that the probability of life existing is \> 0. That is evidence. Now, as to how far beyond zero that is, it is surely higher given that we know of intermediate stages between life and non-life (viruses, prions) as opposed to the simplest entity being a cell. Wrong on both counts. No, it is not higher, and prions and viruses are not intermediate stages between life and non-life. ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [May 10, 2011, 3:34am UTC](https://boards.straightdope.com/t/are-we-alone/580981/79 "2011-05-10T03:34:31Z")
> [@Voyager](#): > > Of course all existing viruses have evolved to be dependent on truly living things. Ahhh, no. They evolved \*from \*living things. They are no more examples of protolife than your eyeballs or any other part of your body that has also “evolved to be dependent on truly living things”. By some standards viruses are the most highly evolved lifeform on the planet. There is certainly no doubt that they are descended form living cells, rather than being some sort of proto-life. > [@](#): > > We don’t know what p is exactly, but I think there is good reason to believe that it isn’t ll that small. And what is that good reason? > [@Paranoid\_Randroid](#): > > do we have any idea whether other planetary systems/stellar systems/galaxies are comparable to ours with respect to their suitability for life? No. > [@](#): > > Do we even know enough about how the _unique_ circumstances on earth contributed to the rise of intelligent life to make statements about how probable it was? No, and that is the biggest hurdle. We have \*absolutely \*no idea what teh conditions were for the development of life on Earth. An I mean absolutely no idea. We don’t know if it happened in the ocean, on dry land, in the soil or in the clouds. We don’t know what the atmospheric composition or temperature or energy inputs were at the time. We don’t know if life as we see today is first stage life, or if it is second stage life that was crated by earlier non-DNA life, or if it is third or even later stage life. Life as we see it today may well be descended from clay based life through protein life to lipid life to RNA life culminating in DNA life. And every novel lifeform outcompeted and exterminated its own ancestors. Hell, we don’t even know that life originated on Earth. It may have originated in outer space or even in \*intergalactic \*nebulae. Then we can move onto more specific requiremnts, such as the requirement for a large moon which requires a collision between two planets at the precise angle at the precise time. The existence of the moon is an extremely improbable event by itself. Maybe only one in a trillion planets that are otherwise identical to Earth even have moons. And that is just one small factor at play. And those aren’t fanciful theories I just made up. Those are all accepted hypotheses published in the premier journals in the field. When I say that we have absolutely no idea, I mean that we have absolutely no idea. The experts in the field can’t even resolve whether life even originated on Earth. Those who do champion a terrestrial origin can;t resolve whether the first proto-life was even _organic_. There are seriously those who believe that he first evolving organisms were clay beds or crystal micropores. And those who do champion an organic origin can’t resolve whether the first life was protein, nucleic acid, lipid, micropore or even more exotic material. We simply have no idea what the conditions were for the origin of terrestrial life. ---
**Author:** ![mac\_bolan00](https://avatars.discourse-cdn.com/v4/letter/m/b3f665/32.png) [@mac\_bolan00](https://boards.straightdope.com/u/mac_bolan00)\ **Post date:** [May 10, 2011, 8:55am UTC](https://boards.straightdope.com/t/are-we-alone/580981/80 "2011-05-10T08:55:41Z")
but even if we will never know exectly how life on earth could have started, terrestial formation of life does not violate physical laws. it is possible, logical. [Previous page](https://boards.straightdope.com/t/are-we-alone/580981.md?page=3) [Next page](https://boards.straightdope.com/t/are-we-alone/580981.md?page=5)