Binyamin Tsadik Posted July 16, 2012 Share Posted July 16, 2012 Even if alien life did exist in other galaxies, because information about these galaxies takes thousands of light years to reach us, even if there are other civilizations as advanced as we are, it would be thousands of years before we could see the evolution of their underwater life. In fact, the universe could be populated with intelligent life in every galaxy, sending out radio signals, but by the time we get them our sun will have undergone a super-nova. Link to comment Share on other sites More sharing options...
CaptainPanic Posted July 16, 2012 Share Posted July 16, 2012 Here's a picture of all the stars within 50 lightyears from us. We've started making radiowaves approximately 100 years ago... so if those stars have alien life, and they wanted to talk back to us, only these few stars are close enough that the signal would have reached us by now. But that number of stars is growing really (really) fast. The number of stars within the "bubble" where our signals have traveled is a 3rd power function of time (volume is a third power function of radius). 1 Link to comment Share on other sites More sharing options...
Binyamin Tsadik Posted July 16, 2012 Author Share Posted July 16, 2012 Here's a picture of all the stars within 50 lightyears from us. We've started making radiowaves approximately 100 years ago... so if those stars have alien life, and they wanted to talk back to us, only these few stars are close enough that the signal would have reached us by now. But that number of stars is growing really (really) fast. The number of stars within the "bubble" where our signals have traveled is a 3rd power function of time (volume is a third power function of radius). Yes, if intelligent life is in our Galaxy, or even non-intelligent life, we will theoretically be able to observe it if we had a device that could do so. However, the closest Galaxy is approximately 2.5 million light years away. So unless there was life that long ago, we would not even be able to theoretically observe it. And even if we did observe it at some point, it would take twice that long in order to have a 2 way communication, and that is assuming that in another 2.5 million years they would not have already answered their own questions. Link to comment Share on other sites More sharing options...
CaptainPanic Posted July 16, 2012 Share Posted July 16, 2012 Oh, I missed the fact that you specifically talk about other galaxies. Yeah, we'll only get the old news from them. Link to comment Share on other sites More sharing options...
Moontanman Posted July 16, 2012 Share Posted July 16, 2012 Yes, if intelligent life is in our Galaxy, or even non-intelligent life, we will theoretically be able to observe it if we had a device that could do so. However, the closest Galaxy is approximately 2.5 million light years away. So unless there was life that long ago, we would not even be able to theoretically observe it. And even if we did observe it at some point, it would take twice that long in order to have a 2 way communication, and that is assuming that in another 2.5 million years they would not have already answered their own questions. Yes but the insinuation that first contact must come from a different galaxy is a bit of a strawman isn't it? As CaptainPanic pointed out There are many stars with in a reasonable distance from us, "one or two" of the most interesting lie 4.5 light years away, two sun like stars high metal content and quite possible two planetary systems. While I don't really expect a flying saucer to land on the White House lawn anytime soon to say we will never even make radio contact is more than a bit pessimistic I think... Link to comment Share on other sites More sharing options...
michel123456 Posted July 16, 2012 Share Posted July 16, 2012 (edited) Here's a picture of all the stars within 50 lightyears from us. We've started making radiowaves approximately 100 years ago... so if those stars have alien life, and they wanted to talk back to us, only these few stars are close enough that the signal would have reached us by now. But that number of stars is growing really (really) fast. The number of stars within the "bubble" where our signals have traveled is a 3rd power function of time (volume is a third power function of radius). I remember having read somewhere that as the signal spreads away, it loses its strength very quickly and becomes a "noise" no other hypothetical alien civilization could recognize. Edited July 16, 2012 by michel123456 1 Link to comment Share on other sites More sharing options...
CaptainPanic Posted July 16, 2012 Share Posted July 16, 2012 I remember having read somewhere that as the signal spreads away, it loses its strength very quickly and becomes a "noise" no other hypothetical alien civilization could recognize. Our signals indeed fade quickly (just like all waves that originate from a point source). If we know the intensity of the intergalactic background noise, we should be able to calculate when the average radio transmission becomes unrecognizable (when it becomes significantly weaker than the noise itself). You'd expect that the guys at SETI have thought about this? What else do they expect to find? 1 Link to comment Share on other sites More sharing options...
Moontanman Posted July 16, 2012 Share Posted July 16, 2012 Our signals indeed fade quickly (just like all waves that originate from a point source). If we know the intensity of the intergalactic background noise, we should be able to calculate when the average radio transmission becomes unrecognizable (when it becomes significantly weaker than the noise itself). You'd expect that the guys at SETI have thought about this? What else do they expect to find? This is something I've given considerable consideration to as well. It is often said that the radio telescope at Arecibo Puerto Rico is able to pick up a signal from a alien civilization half way across the visible universe or something like that. But the reality is that it could only detect a similar telescope that was intentionally beaming a signal directly at us, an unlikely event to be sure. To detect an earth like civilization nearby requires they focus on that one star for a period of time, they are doing a star to star search nearby but so far only null results... I'm not sure how the interstellar interference mentioned is allowed for but it is true that the Earths signals fade before they would be picked up by anything but an intensive search before they get to the nearest star... Link to comment Share on other sites More sharing options...
Spyman Posted July 16, 2012 Share Posted July 16, 2012 What the SETI guy Seth Shostak thought 2003: Can Aliens Find Us? Oct. 23, 2003 by Seth Shostak - Senior Astronomer Radio was invented in the 19th century, and large-scale broadcasting began in the 1920s. Alas, these early broadcasts were of low power, and at low frequency. The difficulty with low frequency transmissions, such as AM radio, is that they are refracted by Earths ionosphere, and have difficulty making it into space. However, beginning in the 1950s, we started to construct high-power, high frequency transmitters for radar, for FM radio, and for television. These signals leaked off the planet, and headed for the stars. A modern TV transmitter can put out as much as a megawatt of power. Its not very tightly focused, so even though much of the broadcast energy spills into space, its fairly weak by the time it reaches another star system. Consider one of our early TV programs just washing over a planet thats 50 light-years away. To detect the "carrier" signal from this broadcast in a few minutes time would require about 3,000 acres of rooftop antennas connected to a sensitive receiver. Thats a lot of antennas, and an unsightly concept. But its not hard to build, and the aliens could conceivably do it. If the extraterrestrials were unwise enough to actually want to see the program, then theyd need an antenna about 30,000 times greater in area (roughly the size of Colorado). Ambitious, but possible. A rather easier task would be to detect our military radars. The bigger ones typically boast a megawatt of power, and are focused into beams that are a degree or two across. There are enough such radars that, at any given time, they cover a percent of the sky or so. The signal from the most powerful of these could be found at 50 light-years distance in a few minutes time with a receiving antenna 1,000 feet in diameter. Indeed, these military radars are the only signals routinely transmitted from Earth that are intense enough to be detectable at interstellar distances with setups equivalent to our own SETI experiments. Bottom line? With radio technology slightly more advanced than our own, Homo sapiens is detectable out to a distance of roughly 50 light-years. Within that distance are about 5,000 stars, all of which have had the enviable pleasure of receiving terrestrial television. And each day, a fresh stellar system is exposed to signals from Earth. http://archive.seti.org/news/features/can-aliens-find-us.php 3 Link to comment Share on other sites More sharing options...
Binyamin Tsadik Posted July 17, 2012 Author Share Posted July 17, 2012 Oh, I missed the fact that you specifically talk about other galaxies. Yeah, we'll only get the old news from them. It's okay! Your point is very important, if there are other lifeforms in our Galaxy, then first contact is possible. It really just depends on the probability of life to exist in our universe. The density of life planets across the universe should theoretically be more or less evenly distributed, yet there is still a chance that two such planets exist in a single galaxy. Also, if the probability is high enough for life-planets to exist then the average distribution could be 2 per Galaxy. I was operating under the assumption that life planets are exceedingly rare. At least as rare as 1 per Galaxy. Link to comment Share on other sites More sharing options...
too-open-minded Posted July 17, 2012 Share Posted July 17, 2012 the fact that we havent made contact inspires me to think that their is intelligent life out their 2 Link to comment Share on other sites More sharing options...
Severian Posted July 17, 2012 Share Posted July 17, 2012 (edited) I don't think first contact is ever possible. The calculations that lead one to believe that other life exists in the universe are using the sheer number of stars to infer likelihood. The number of stars is huge but the probability of any particular one holding life is tiny. If you look at our local space (i.e. space we could conceivably communicate with) then the number of stars is still far too small for life to be likely, never mind intelligent life. Then you have to take into account not only spatial distance, but temporal distance. Even if a civilization remains technologically advanced for 100,000 years(!) that is still only one millionth of the age of the universe. So if, by some extraordinary coincidence, there were some other civilization that called our local area home, the chances are we will not overlap in time. We may as well try to communicate with ancient Babylon. Edited July 17, 2012 by Severian Link to comment Share on other sites More sharing options...
CaptainPanic Posted July 17, 2012 Share Posted July 17, 2012 We're talking about the Drake equation (copypasted from wikipedia): The Drake equation states that: [math] N = R^{\ast} \cdot f_p \cdot n_e \cdot f_{\ell} \cdot f_i \cdot f_c \cdot L[/math] where: N = the number of civilizations in our galaxy with which communication might be possible; and R* = the average rate of star formation per year in our galaxy fp = the fraction of those stars that have planets ne = the average number of planets that can potentially support life per star that has planets fℓ = the fraction of the above that actually go on to develop life at some point fi = the fraction of the above that actually go on to develop intelligent life fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space L = the length of time for which such civilizations release detectable signals into space I don't think first contact is ever possible. The calculations that lead one to believe that other life exists in the universe are using the sheer number of stars to infer likelihood. The number of stars is huge but the probability of any particular one holding life is tiny. If you look at our local space (i.e. space we could conceivably communicate with) then the number of stars is still far too small for life to be likely, never mind intelligent life. Then you have to take into account not only spatial distance, but temporal distance. Even if a civilization remains technologically advanced for 100,000 years(!) that is still only one millionth of the age of the universe. So if, by some extraordinary coincidence, there were some other civilization that called our local area home, the chances are we will not overlap in time. We may as well try to communicate with ancient Babylon. Yes, but as the universe ages, it becomes more and more likely that (1) life develops and (2) it becomes intelligent. Judging by how stuff went on earth, especially intelligence needs a lot of time, and is more likely to happen as a planet or star system ages. So, in the Drake equation, fℓ, fi and fc will increase over time. Also, what proof do we have that there is not some minimum technological knowledge after which a civilization cannot go extinct anymore? Babylon came and went, but humans - on average - became more and more advanced. Why would every civilization have some expected life time? Why can't L be all the time between the first signal sent into space, and now? That would mean that L also is an ever increasing value. I agree that the cosmic radiosilence gives us nothing to conclude that there is life out there, but I think you're being unnecessarily pessimistic. Link to comment Share on other sites More sharing options...
D H Posted July 17, 2012 Share Posted July 17, 2012 Yes but the insinuation that first contact must come from a different galaxy is a bit of a strawman isn't it? It's not so much a straw man so much as unstated assumption that intelligent life is rare. Binyamin Tsadik made this assumption explicit in a subsequent post. I hold a similar view, that (extant) intelligent life is rare, exceedingly rare. It is, I think, the best answer to Enrico Fermi's question, Where are they?, and to Stephen Hawking's question, Why would they [uFOs] appear only to cranks and weirdos? It explains why we don't see any Dyson spheres, why we see stellar nurseries (what better place is there for von Veumann probes to reproduce?), why after fifty years of looking SETI has found nothing that is even close to definitive. While I don't really expect a flying saucer to land on the White House lawn anytime soon to say we will never even make radio contact is more than a bit pessimistic I think... Pessimistic? Why? It is perhaps pessimistic if intelligent life arises frequently but is inevitably doomed to a quick demise. However, if intelligent life arises but rarely, then this is a good sign. It means the galaxy is our oyster. It is often said that the radio telescope at Arecibo Puerto Rico is able to pick up a signal from a alien civilization half way across the visible universe or something like that. It is often said? By whom? That's a "citation needed" kind of statement. Link to comment Share on other sites More sharing options...
CaptainPanic Posted July 17, 2012 Share Posted July 17, 2012 [...]to say we will never even make radio contact is more than a bit pessimistic I think... Pessimistic? Why? Because "never" is a word that implies that the chance is zero. Not tiny, but zero. I totally agree that all evidence that we have now is that the odds are small, but I do not yet conclude it is zero. Therefore, I agree with Moontanman that the conclusion that we will "never" make contact is pessimistic, because it is my opinion that it underestimates the chance. It is perhaps pessimistic if intelligent life arises frequently but is inevitably doomed to a quick demise. However, if intelligent life arises but rarely, then this is a good sign. It means the galaxy is our oyster. It would be anyway. We've shown plenty of times how ruthless we can be with other life forms... ask the Neanderthals. You're turning it around: we defined the goal to find life. Thus overestimating the odds is optimistic, and underestimating is pessimistic. 1 Link to comment Share on other sites More sharing options...
Moontanman Posted July 17, 2012 Share Posted July 17, 2012 It's okay! Your point is very important, if there are other lifeforms in our Galaxy, then first contact is possible. It really just depends on the probability of life to exist in our universe. The density of life planets across the universe should theoretically be more or less evenly distributed, yet there is still a chance that two such planets exist in a single galaxy. Also, if the probability is high enough for life-planets to exist then the average distribution could be 2 per Galaxy. I was operating under the assumption that life planets are exceedingly rare. At least as rare as 1 per Galaxy. Why would you assume one civilization per galaxy? More than 100 billion stars in our galaxy and it would appear that most stars have planets. We have already found two possible earth like planets in the "Goldilocks" zone relatively near the Earth. I don't think first contact is ever possible. The calculations that lead one to believe that other life exists in the universe are using the sheer number of stars to infer likelihood. The number of stars is huge but the probability of any particular one holding life is tiny. If you look at our local space (i.e. space we could conceivably communicate with) then the number of stars is still far too small for life to be likely, never mind intelligent life. It's difficult to really dispute this but there is no reason yet to assume it to be true either. Then you have to take into account not only spatial distance, but temporal distance. Even if a civilization remains technologically advanced for 100,000 years(!) that is still only one millionth of the age of the universe. So if, by some extraordinary coincidence, there were some other civilization that called our local area home, the chances are we will not overlap in time. We may as well try to communicate with ancient Babylon. Another good point but it also relies on some assumptions, it assumes that civilizations do not last indefinitely, if many of them do the longer they last the more likely contact is... It's not so much a straw man so much as unstated assumption that intelligent life is rare. Binyamin Tsadik made this assumption explicit in a subsequent post. I hold a similar view, that (extant) intelligent life is rare, exceedingly rare. It is, I think, the best answer to Enrico Fermi's question, Where are they?, and to Stephen Hawking's question, Why would they [uFOs] appear only to cranks and weirdos? It explains why we don't see any Dyson spheres, why we see stellar nurseries (what better place is there for von Veumann probes to reproduce?), why after fifty years of looking SETI has found nothing that is even close to definitive. I wonder if civilizations even bother with deep gravity wells, why even come in close to any star when the ort clouds of stars are full of everything you need for colonies. They could actually be in the ort cloud of the sun and we would not know it. "Why UFOs only appear to cranks and weirdos" is simply not true, there are hundreds of sightings by competent observers, multiple observers, radar and and all of the above at once, hundreds possibly thousands, some by astronomers and even physicists, some of them famous, in the late 40's and early 50's at Los Alamos National Laboratory is one example... UFOs might indeed not be real but to categorize anyone who sees them as cranks and weirdos is not supported by the evidence... Pessimistic? Why? It is perhaps pessimistic if intelligent life arises frequently but is inevitably doomed to a quick demise. However, if intelligent life arises but rarely, then this is a good sign. It means the galaxy is our oyster. I agree, estimates of our ability to colonize the galaxy with no magical technology look like a few million years at most... where indeed are they? Already here and ignoring us as completely as we ignore ants? It is often said? By whom? That's a "citation needed" kind of statement. You are correct and I can't provide, I have heard that statement many times and read it i am sure but I can find no basis for it. But I did find this http://www.faqs.org/faqs/astronomy/faq/part6/section-12.html#b Also i think it should be said that even if there are 1000 civilizations in our galaxy, if reasonably well distributed they would still be likley to be beyond our radio horizon unless they were specifically trying to contact others. 1 Link to comment Share on other sites More sharing options...
Pix Posted July 17, 2012 Share Posted July 17, 2012 I think any advanced civillization would not be useing radio . quantum entanglement allows for faster then light communications . Pix Even if alien life did exist in other galaxies, because information about these galaxies takes thousands of light years to reach us, even if there are other civilizations as advanced as we are, it would be thousands of years before we could see the evolution of their underwater life. In fact, the universe could be populated with intelligent life in every galaxy, sending out radio signals, but by the time we get them our sun will have undergone a super-nova. Link to comment Share on other sites More sharing options...
Moontanman Posted July 17, 2012 Share Posted July 17, 2012 I think any advanced civillization would not be useing radio . quantum entanglement allows for faster then light communications . Pix Bold by me: Now that I'd like to see some support for... Link to comment Share on other sites More sharing options...
Severian Posted July 17, 2012 Share Posted July 17, 2012 Also, what proof do we have that there is not some minimum technological knowledge after which a civilization cannot go extinct anymore? Babylon came and went, but humans - on average - became more and more advanced. Why would every civilization have some expected life time? Why can't L be all the time between the first signal sent into space, and now? That would mean that L also is an ever increasing value. It is the same argument to insist that there is life out there. A small probability becomes a certainty when you have a large enough sample of a long enough time scale. We nearly destroyed humanity over the Cuban Missile Crisis, so the probability of a "civilized" society destroying itself is not very small. Give us 100,000 years and even better technology for destroying ourselves and it will surely come. Link to comment Share on other sites More sharing options...
md65536 Posted July 20, 2012 Share Posted July 20, 2012 (edited) quantum entanglement allows for faster then light communications . Nah. Entanglement doesn't allow other laws to be broken and special relativity prohibits this. There is no accepted, testable theoretical prediction of FTL communications. All quantum mechanical experiments so far, even the weirdest, are consistent with the conclusion that no useful information travelled faster than light. We're talking about the Drake equation (copypasted from wikipedia): [...] fi = the fraction of the above that actually go on to develop intelligent life fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space There must be something flawed about using fractions or statistics to estimate something like this. It seems to me it is like asking "What fraction of species on Earth have developed use of a written language?" It's meaningless as a fraction because there's only one (assumed), but the fraction depends on how many other unknown species there are. Well, we're pretty sure we're the only such species on Earth, but if we were to assume we weren't then how could you possibly come up with a reasonable estimate for that fraction? It's meant to be a measure of the subset of species with intelligence, but its value ends up being a measure of that set's complement. If the true value of that fraction is 1 in ten million, or if it is 1 in a hundred million, how many species who have developed written language does either value represent?, and how does either value relate to the probability of a chance encounter with such a species? I think the problem is that we think like "There must be others like X", where X is something that we only know about because we're like X. We realize it's a bad assumption to think that we're somehow the only "special" thing in the universe, but that doesn't mean that it can't be common for things to be unique in the universe. Current human-known communications methods might be somewhat unique. Our concept of intelligence might be unique to Earth. True, evolution seems like a universal principle, but what we consider to be "intelligence", and our idea that it is universally advantageous, might be only an assumption based on it being the only thing we know. There may be other forms of "highly evolved advancement" that are not like what we know as intelligence, that we can't even fathom and may be unable to recognize, because it's not what we know. Humans wondering about what form of languages (systems of symbols) an alien life might use might be like ants wondering if there exist any creatures that use really advanced pheromones. Related: http://xkcd.com/638/ Edited July 20, 2012 by md65536 2 Link to comment Share on other sites More sharing options...
CaptainPanic Posted July 20, 2012 Share Posted July 20, 2012 As far as I understood, the equation does not make any predictions about the unknowns, and it does not claim that it will enable anyone to make a reasonable estimate of the number of civilizations in our galaxy with which communication might be possible (with our current knowledge). But if we would have sufficient data, this equation will probably enable us to calculate a reasonable estimate. The problem is the lack of data, not the equation. Still, we started this thread to talk about the topic, and we are hampered by a lack of data just as much as the person who thought up that formula (that's probably Mr. Drake). Link to comment Share on other sites More sharing options...
Bill Angel Posted July 20, 2012 Share Posted July 20, 2012 I remember having read somewhere that as the signal spreads away, it loses its strength very quickly and becomes a "noise" no other hypothetical alien civilization could recognize. That's true, but I should think we should still be able to detect hydrogen bomb explosions on an alien planet , just as alien civilizations might be able to detect hydrogen bomb explosions on earth. Link to comment Share on other sites More sharing options...
Moontanman Posted July 20, 2012 Share Posted July 20, 2012 That's true, but I should think we should still be able to detect hydrogen bomb explosions on an alien planet , just as alien civilizations might be able to detect hydrogen bomb explosions on earth. Can you provide a mechanism for detecting exploding hydrogen bombs over interstellar distances? Link to comment Share on other sites More sharing options...
moreinput Posted July 27, 2012 Share Posted July 27, 2012 Maybe with what we have at our disposal now it creates the illusion of impossibility? You, nor could I predict what time will bring, or how we will manipulate it for our own purposes. I like to to bear in mind when dealing with exploration. That at one point, not quite as long ago as we would like to think. Sailing around this "cube" of a planet was in impossibility. However, time in this case showed us that it was in fact our undereducated perception that misguided our views. It is important to let go of what you know when analyzing something new. So I am not saying this analogy will ring true in the search for other life and the distances/time it would take to reach. But if you allow your mind to remain in the fish tank that others have built around you. Then your mind will in fact remain in the fish tank that others have built around you. Basically what I am saying is this question/perception is in need of more input before you can receive the proper output. So instead of jumping to conclusions based on what I am sure in few hundred years from now, will be considered our arcane point of view. You should ask yourself what is the "cube" that we are seeing now that prevents us from achieving our goals and desires. What is our misguided and undereducated perception..Answer this and it would make you an immortal. Your name would be known by everyone for centuries and maybe more. Contradiction of our capability however will bring you no such glory. 2 Link to comment Share on other sites More sharing options...
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