Message boards :
SETI@home Science :
Results
Message board moderation
Previous · 1 · 2
Author | Message |
---|---|
Taurus Send message Joined: 3 Sep 07 Posts: 324 Credit: 114,815 RAC: 0 |
To measure our progress we should trend how much of the observable space-time we have examined. Such a metric is in fact a measure of how confident we are that ET does not exist (within our model). Being "literal" in this case is mandatory because the distinction between "ET" and "a radio signal within a narrow band of frequencies currently passing over the Earth which was broadcast by an alien civilization" is a very important one. This is obvious. It is absolutely, unequivocally ***NOT*** the case that any measure of SETI's progress is also a measure of how confident we are that ET does not exist. By definition it could ONLY ever be a measure of how confident we are that there is no radio signal currently passing over the Earth which was broadcast by an alien civilization within the band of frequencies we are scanning. I say again, this is obviously not the same as "ET does not exist". |
Taurus Send message Joined: 3 Sep 07 Posts: 324 Credit: 114,815 RAC: 0 |
I agree with you that if there are other civilizations, then there are many I know of no reason to assume this. that we will not 'hear' from the low-tech end of the distribution. IF the speed of the technological development here on Earth is the norm for any civilization of intelligent organisms, then it would be extremely unlikely that there are currently ANY civilizations of intelligent organisms roughly the same or more primitive than we are in the galaxy. Our civilization has existed for roughly ~10,000 years, and if this is the normal time in which it takes for the development of radio transmitters, then I can't imagine we currently coincide with any other civilization that is coincidentally within that same 10,000 year period of time given the cosmic timescale of the universe. It also seems likely to me that we will not 'hear' from the high end, either, unless they are actively looking for us It's not difficult to imagine that since any technological civilization would also necessarily have science, they would be interested in the same kinds of astronomical research that we are. Such a civilization could easily have observed and cataloged every visible star in the entire galaxy (which wouldn't take a very long period of time given the right technology) and potentially have extensively studied each star and its planets. If they have done so, then they already know about our Sun and our planet Earth. Even if their technology were no more than equal to ours, they could perform a spectral analysis of our atmosphere and would discover free Oxygen. They would presumably know that there is essentially no natural process other than life which could be responsible for the free Oxygen in our atmosphere, and thus would at least know that life exists on our planet. This knowledge might spur them to undertake further scrutiny of our world, and if they speculated that an intelligent civilization might exist here someday they might start a long-term signaling effort. There is of course no evidence that some civilizations have "persisted for millions, if not billions of years", nor does that claim seem likely. What makes you assume that this isn't likely? If it isn't the case, then statistics alone suggests it would be virtually impossible for two technological civilizations to coincide at the same time if more modest estimates of the likelihood of civilizations arising at all are correct. Simply plugging some numbers into the Drake Equation could tell you that. Instead, it seems that Earth's history seems to be very uneventful. Proto-Earth's collision with a Mars size planetesimal in the nascent solar system was not only "eventful" but also unlikely since both proto-planets coincidentally developed along roughly the same orbital distance from the Sun. Earth is also the only known terrestrial planet in the solar system with currently active plate tectonics and a strong magnetic field. Earth's active geology is very unusual indeed and most scientists believe it has gone hand in hand with the evolution of life. The accumulation of free Oxygen in Earth's atmosphere and the development of the Ozone layer which protected Earth's surface from the common radiation of space was also quite eventful. There is also no evidence I'm aware of that our evolution has been slowed or accelerated by unusual events. The rise of free Oxygen in Earth's atmosphere was necessary for complex animal organisms to develop and not only caused a global mass extinction but also eventually resulted in an abrupt and drastic spike in the size of living organisms. The Snowball Earth event, which may have been brought about as a direct result of plate tectonics on Earth, is associated with another abrupt and drastic spike in the size and complexity of organisms as the global glaciation receded. Though the classical notion of a Cambrian explosion is somewhat obsolete, the end of Snowball Earth coincides with the rise of multicellular creatures in the Ediacaran Period shortly before the Cambrian. Of course, the many mass extinctions after the Cambrian could obviously be considered "unusual events" and they certainly slowed AND accelerated the evolution of life on Earth. Some of these mass extinctions, such as the Permian-Triassic extinction, were likely the result of geologic activity. Indeed, there is a great deal of evidence for a cataclysmic volcano event in what is now modern day Siberia that may have brought about the PT extinction. So if we hear from a typical civilization, we will hear from beings similar to ourselves, albeit referenced at some time in the recent past Only "similar" in that they possess the technology to transmit radio signals and therefore the prerequisite intelligence and subsequent scientific endeavors to develop such technology in the first place. Beyond that, how "similar" they are to us is open to a great deal of speculation. Every SETI scientist who has ever publicly speculated on the age of any civilization we might hear from has always suggested that such a civilization would almost certainly be much older than us. Seth Shostak has even gone so far as to speculate that such a civilization would probably consist of artificially intelligent machines rather than biological organisms. Given that we cannot expect to hear from ET if he is too far away because the signals would not be here yet, nor will they be strong enough, I suspect that our most likely hit will be close to us. You're right that radio signals generated too far away would have to be impractically strong for us to detect them, but I think ET has had plenty of time to send us a signal. How close? It sounds like 100 l-y is some sort of reasonable estimate of our current abilities, from John's statement below. That means that the detectable ET's will be similar to ours technologically. Not sure I follow where your assumption on ET's level of technology is coming from. In a sense the level of technology used to generate the signal would necessarily be "similar" to ours since we only have the technology to detect the generation of signals we ourselves are capable of generating. That doesn't mean that ET's level of technology need be the same as ours on the whole. A tribe of indigenous people living in a secluded forest may not be capable of detecting signals generated by your cell phone, but if you wanted to communicate with them you're still more than capable of beating a drum or using smoke signals if you choose. I also think that counting the wu's is not a measure of our progress and it is shortsighted to think so. I actually agree. I posted that there have been billions of detections and millions of WUs processed because this the result of PCs "crunching numbers" as the OP suggested. The reason that SETI@Home cannot measure its progress the same way other projects might is that the information it sends out as WUs is just a record of where the Aricebo telescope happened to have been pointed at any time. For SETI's purpose it's essentially random, not a directed effort to scan the entire sky "piece by piece" as it were. The SETI Institute are the ones undertaking a directed, "piece by piece" effort. If you like, I can post articles and sources for everything I referenced. |
PhonAcq Send message Joined: 14 Apr 01 Posts: 1656 Credit: 30,658,217 RAC: 1 |
To measure our progress we should trend how much of the observable space-time we have examined. Such a metric is in fact a measure of how confident we are that ET does not exist (within our model). Ugh. Perhaps instead of "literal" I should have said "pedantic". Arm-chair scientists and theologians spend time spouting about absolutes and unobservables, and writing books for the other arm-chair scientists and theologians on the same topics. All I'm trying to get across to you is that scientific investigation begins with a premise, replete with a detailed framework within which the investigation can be performed. In our case, SETI@HOME has an observable universe that is reduced from the usual understanding of the term for various technical factors. Nevertheless, SETI@HOME should report progress against its objectives. It is more or less a waste of time arguing here about whether ET exists outside of the SETI@HOME experimental conditions. It is not the point. Your emotional fervor seems wasted debating the absolute existence of ET on the project message board. Perhaps the Planetary society is a better location? |
Taurus Send message Joined: 3 Sep 07 Posts: 324 Credit: 114,815 RAC: 0 |
How do we know we have a short history? What do you compare to? We have a few choices of what we can compare it to: - The age of the Universe - The age of the Milky Way Galaxy - The period of time at which enough metalicity accumulated in our galaxy for newborn stars to develop rocky terrestrial planets - The average age of such rocky terrestrial planets within our galaxy - The age of the Earth - The period of time in which life has existed on Earth - The period of time in which complex animal organisms have existed on Earth - The period of time in which Homo sapiens has existed on Earth Our civilization has existed for roughly ~10,000 years; compared to even the total amount of time in which our species has existed on Earth (roughly ~150,000 years), the timescale of our civilization's existence is not only very apparent but almost awesome in its brevity. How do we know they all started at the same time? We don't think they all started at the same time. We can however determine other things, such as the earliest possible time at which a planet like the Earth could have formed within the habitable zone of our galaxy. Since the Earth is a rocky, terrestrial world it could not have formed without elements heavier than Hydrogen and Helium which were the only two elements that originally existed in the early universe. Only processes such as supernovae can form elements heavier than Hydrogen and Helium. Using models of the evolution of our galaxy, one can determine when enough "metalicity" (elements heavier than Hydrogen and Helium) was proliferated for planets like the Earth to form in the first place. Studies have been undertaken by scientists such as Charles Lineweaver to determine this, and it's been found that the average age of terrestrial rocky planets throughout our galaxy is over 1 billion years older than the Sun. How do we know others civilizations haven't evolved more rapidly or less rapidly? This is pretty much a moot point due to the vastness of the timescales involved. When you say "more or less rapidly", do you mean their technology? Or do you mean the time it took for their species to exist in the first place? Let's say there's another planet out there that developed at *exactly* the same time as Earth and is *exactly* as old as Earth is, ~4.5 billion years. Let's also assume that life got started on their planet at *exactly* the same time as it did on Earth, ~3.5 billion years ago. Say their planet had more ideal conditions for life than Earth did. Rather than ~4.5 billion years, let's say it took ~3.5 billion years for their species to come about. That means their species developed 1 billion years ago while ours developed 150,000 years ago. Pretty substantial difference. But let's say their technology didn't develop as fast as ours. Let's say, for whatever reason, they did not really have anything that could be considered a civilization for....500,000 years. That's half a million years!..... Now let's say they weren't big on science...maybe science and technological advancement progressed VERY slowly. Let's say it took them 1 million years to develop radio transmitters. If that's the case then it would mean that their radio transmitting civilization is 998,500,000 years older than ours. Let's say they developed their civilization extremely quickly. Much more quickly than we did. Let's say they developed civilization just 20,000 years after their species arose. And let's say it took them just another 1,000 years to develop radio transmitters. That would mean their radio transmitting civilization is 999,970,000 years older than ours. But let's say that intelligent life itself did not develop after 3.5 billion years on their planet. Let's say it developed after 4 billion years. If we assume the exact same scenarios for the development of their civilization and radio transmitters as above, then their civilization is either 498,500,000 years or 499,970,00 years older than ours. If we assume it took longer than 4.5 billion years for their planet to develop intelligent life....perhaps as little as 1 million years longer, then their species does not exist yet. Now assume that their planet is NOT exactly the same age as the Earth (which is the more likely scenario). You could also assume that life did not originate on their planet roughly ~800 million years after their planet first formed, exactly the same as it did on Earth. This is also a more likely scenario. Do you see where I'm going with this? If you use the life of radio on Earth, say 200 years, as the time scale, then we might be receiving radio signals from some planet within 200 light years of us right now. The first working radio transmitter was built just a little over 100 years ago, not 200 years ago. I can't figure out why you assume that the period of time in which radio transmission technology has existed on Earth would be exactly equal to the distance in light years to an alien civilization currently transmitting a radio signal to Earth. |
Taurus Send message Joined: 3 Sep 07 Posts: 324 Credit: 114,815 RAC: 0 |
Ugh. Perhaps instead of "literal" I should have said "pedantic". The only "absolute" I'm arguing is the actual basis on which this project operates which a SETI scientist or a google search could tell you. The distinction between this project and the conclusion you're attempting to draw from it is a very fundamental one. Nevertheless, SETI@HOME should report progress against its objectives. It can't report the progress you want from it. Not honestly anyway. The people behind SETI@Home know this. The people at the SETI Institute know this. The people behind every serious SETI project around the world know this. ...which is why you will never find one single SETI scientist claim that his work can conclusively contribute to the confidence level in the assertion "ET does not exist". It is no coincidence that people who have devoted far more time and energy to SETI than you or I have are not framing things the way you want them framed. It's not because they never bothered to think of it in those terms. It's because they know the premise is false. It is more or less a waste of time arguing here about whether ET exists outside of the SETI@HOME experimental conditions. Well, my entire point has been that you're attempting to frame SETI@Home's "progress" in way that is outside of its actual experimental conditions! Of course, it could be considered an equally wasteful use of time posting on these forums at all, since I'm fairly certain that the only worthwhile contributions you or I could make to the SETI@Home project are PC crunch time or monetary donations. ;) |
PhonAcq Send message Joined: 14 Apr 01 Posts: 1656 Credit: 30,658,217 RAC: 1 |
You must have a lot of time on your hands. But I'll try to respond... I agree with you that if there are other civilizations, then there are many If you assume there is one other civilization out ther, then there would be two 'special' cases. This situation would be as untenable to many people as the existence of a single special case. It is easier for me to believe that either 1) God only created us, or 2) God created a process that developed a distribution of intelligent life forms spread across the Universe, or 3) there is no God and randomness created the distribution anyway.
Your logic or exposition eludes me. Without Divine intervention, it took us about 5B years to get to where we are today, the age of the Earth. Another similar planet in a similar star system would have a similar evolution. But there will be variation. Since we have only produced man-made radio waves for a couple of centuries, it is entirely plausible that the variation in development rates between any two such planets would make a couple of centuries seem small. However, this assumes each planet formed at about the same time. That isn't realistic either. So some started earlier and some later. The result would be a distribution of technical sophistication. The low end would include developmental statuses that are prehistoric by our standards. We won't hear much from them, I suspect.
I agree up to a point. First, if others were at that level, they have done a poor job communicating with us so far. Second, there are something like 10^11 stars in the Milky Way. That would be a very large expensive government program for us to have exhaustively study so many such stars and their planets. If nothing else, the obstacle seems to be merely a statement of economics, even with considerably better technology than we Earthlings have today.
With all due respect to Drake, this equation can probably predict anything you like. It is not a fundamental equation, but rather a guide to thinking. But given that the Universe is 14B years old, that the Earth is about 5B years old, and that organized human civilization is only about 10K years old, it is certainly possible that some planets evolved more quickly to enable a 1By old civilization but I wouldn’t bet on it for a number of obvious reasons.
Again pedantic. My use of the term uneventful does not mean boring or uninteresting. Do any of these events 1) significantly hasten development of life relative to some norm AND 2) would not be likely if a large set of similar solar systems were observed. Comparing Earth history to other planets in this solar system is interesting but not very analytical. It is like saying to your girlfriend that she is the most beautiful girl in the room, when there are no others present.
free oxygen: if necessary here it is likely necessary on ET’s planet, too. snowball: the feeling a message board reader gets when reading these paragraphs. mass extinction: you seem to be on both sides of the fence My point quoted above is that given a typical planet and a typical planet’s evolution toward intelligent life, does theory suggest that we are 6-sigma special. Put another way; are all the mechanisms and events you state going to find parallels on other similar planets in other similar solar systems, thus making our evolution more or less typical? (Rhetorical question here.)
As the kids like to text each other: OMG! I have no idea who I am responding to, but I’m beginning to wonder why I am bothering. Perhaps you have had too much RedBull or some such to structure a reasonable discourse.
Ok, you’re back on track.
My perspective is not based on technology as much as on basic physics. Unless we are dealing with gravity waves, neutrinos, or tachyons beams (being facetious here), our communication with or from ET will be based on the electromagnetic spectrum. Inventive technologies may change how we detect or send such signals, but the signals are essentially limited by Maxwell’s Equations.
My focus is with seti@home here. Piggyback scanning is one of the constraints of the experiment. That is fine. Each scan adds to seti’s observable universe. Just add it up as we go. When locations overlap, that is fine too. We can still state a number corresponding to seti’s observable universe. The spatial component will be in steradians, of course. The radial component (time component) will depend on the detector’s sensitivity at the time and so forth. So that is complex, but doable.
I hesitate to say yes to your offer, but others might find it interesting. If you do, please only list the publications in peer-reviewed professional journals, however. Anything less would be like quoting facts from the Internet or the New York Times: it just is not done in polite company. |
PhonAcq Send message Joined: 14 Apr 01 Posts: 1656 Credit: 30,658,217 RAC: 1 |
Ok, you win. I can't spend more time on the 'measure and report progress' theme with you if you won't or can't read what I am writing. |
Taurus Send message Joined: 3 Sep 07 Posts: 324 Credit: 114,815 RAC: 0 |
Ok, you win. I can't spend more time on the 'measure and report progress' theme with you if you won't or can't read what I am writing. No reason to be needy. The reason I didn't respond until now is that this statement... You must have a lot of time on your hands...is not entirely accurate. Anyway, here goes.
Scenarios 2 and 3 seem equally likely to result in "two special cases" in our galaxy, though I never said anything whatsoever about there being only "one other special case" in our galaxy or the universe for that matter. Whether the distribution of intelligent civilizations throughout the universe is the result of a process initiated by God or merely the result of somewhat random factors, it seems more reasonable to me to assume that civilizations are distributed such that they are fairly rare throughout any given galaxy. There is concrete data behind the reasons for this assumption since there are factors which limit the existence of life or civilizations rather than pure statistical randomness. I've already mentioned some of these factors, while there are others I haven't yet gotten into; - The galactic habitable zone in which stars and their planets are not so close to each other such that terrestrial surfaces would be bombarded by vast amounts of interstellar radiation or subject to wild and intense gravitational interactions. - The level of metalicity from which terrestrial planets can form in the first place. - The size of a star's debris disk, analogous to our Kuiper Belt, from which comets and rocky bodies can collide with a terrestrial planet's surface. A larger, denser debris disk would presumably mean a greater rate and intensity of potentially devastating surface impacts. - The proximity of a large gas giant to deflect or absorb such rocky objects, thus helping to prevent the bulk of them from impacting the terrestrial surface. - A host of local circumstances on the terrestrial planet itself which would be necessary for the formation of something as complex as a DNA analog (an equivalent molecular structure to allow evolution to happen in the first place), such as a strong enough magnetic field to shield the atmosphere from stellar wind, temperatures that would allow for the stable existence of water in liquid form, geologic activity such that something analogous to the carbon cycle can take place, and a large enough moon to create ocean tides which are believed to have been important for the evolution of life on Earth, etc. Due to these factors, and due to the lack of evidence that intelligence itself is useful and adaptive enough such that it would arise independently and in parallel in any given biosphere, I feel it's safe to assume that intelligent living organisms and thus civilizations are likely fairly rare throughout our galaxy if not the universe. Your logic or exposition eludes me. Well, my logic seemed pretty straightforward to me. It's the same logic behind dozens of articles and books written by SETI scientists, astronomers, and enthusiasts. Without Divine intervention, it took us about 5B years to get to where we are today, the age of the Earth. Another similar planet in a similar star system would have a similar evolution. Evolution is not a linear process. I don't think it's necessarily the case that another "similar planet in a similar star system would have a similar evolution". A planet virtually identical to the Earth orbiting a twin of our Sun could have nothing more than microbial mats living on the bottom of its oceans after 5 billion years. However, this assumes each planet formed at about the same time. Nope, that assumption isn't necessary for a few centuries to seem small. A few centuries is a mind-bogglingly small period of time whether contrasting planets which formed at about the same time or at any other time during the 13.7 billion year history of our universe. The result would be a distribution of technical sophistication. The low end would include developmental statuses that are prehistoric by our standards. We won't hear much from them, I suspect. Even if 1 million civilizations have independently arisen in our galaxy as of right now, and even if they arose at purely random points in time in the lifespan of our galaxy, the chances that even one single one of them would just so happen to coincide with the same level of sophistication we had in the last ~100,000 years is astronomically tiny. That would be true whether you assumed that each civilization evolves its technological sophistication at exactly the same rate, at wildly different rates, whether intelligence arises after the same period of time or not. This is fairly straightforward. This is as simple as plotting at the distribution of these civilizations and their level of technological sophistication on a graph. All one million of them. Assume that their planet is a random number of years old anywhere from 13.7 billion to 1 billion (or less if you like), assume it takes a random number of years for life to arise on that planet, assume it takes a random number of years for intelligence to arise, assume it takes a random number of years for civilization to arise, and assume it takes a random number of years for radio transmission technology to be developed. Now plot that out in your head. How many of the 1 million civilizations will perfectly coincide in every single random factor within the extremely narrow window of the last ~100,000 years of technological sophistication on our planet? ...and that, of course, it assuming that there are as many as 1 million civilizations in our galaxy to begin with. See my point? I agree up to a point. First, if others were at that level, they have done a poor job communicating with us so far. How do you figure that? On cosmic timescales, even a million years is a relatively short period of time; we've only been searching for their signal for a few decades. Second, there are something like 10^11 stars in the Milky Way. That would be a very large expensive government program for us to have exhaustively study so many such stars and their planets. Not at all. The Kepler telescope will scan 100,000 stars for Earth-size planets within a period of three years. This is using today's technology and the relative shoe-string budget of a national space program which has seen its funds shrink dramatically over the years. In fact, this telescope is scheduled to launch in less than a month. If Moore's Law holds and computing power continues to increase and become cheaper, and observational methods are refined and expanded (there have already been several exciting papers published this year on new and innovative techniques to scan stars for planets with far more accuracy and efficiency than the technology Kepler will launch with), then it seems inevitable to me that someday the human race will be able to study every visible star within our galaxy without much difficulty in a relatively short period of time. Even if we aren't able to accomplish this for another 1,000 years, remember that 1,000 years is a drop in the bucket. With all due respect to Drake, this equation can probably predict anything you like. It is not a fundamental equation, but rather a guide to thinking. Well, technically so long as each variable is known with a fair degree of confidence, the equation predicts a tangible result. The problem isn't the equation itself, the problem is that while some variables are within our ability to be known with a high degree of confidence (ie; the rate of star formation, the percentage of stars with planets), some are not within our ability to be known at all (ie; the average lifespan of a transmitting civilization, etc). I agree the Drake equation is a guide to thinking and probably obsolete in some ways. But given that the Universe is 14B years old, that the Earth is about 5B years old, and that organized human civilization is only about 10K years old, it is certainly possible that some planets evolved more quickly to enable a 1By old civilization but I wouldn’t bet on it for a number of obvious reasons. I agree. I do not think it's likely that an intelligent civilization could arise on a planet after only 1 billion years. Indeed, I think that if other civilizations exist at all, they've likely come about after periods of time roughly similar to ours. Do any of these events 1) significantly hasten development of life relative to some norm Well, the histories of the other planets in our solar system could be considered a "norm". AND 2) would not be likely if a large set of similar solar systems were observed. The problem is that a large set of similar solar systems hasn't been observed. Even the popular notion of our sun as an "average" star is quaint, simplistic, and somewhat dishonest. First of all, the vast majority of stars in our galaxy are not G Dwarfs like our sun; they are M dwarfs. So technically, the M Dwarf represents the "average star" in our galaxy, and they make up a fairly large chunk of the 10^11 stars you mentioned earlier. There is currently a great deal of doubt in the scientific community regarding whether or not M Dwarfs can host habitable Earth-like planets in the first place. In fact, G Dwarfs like our Sun may make up no more than 10% of the stars in our galaxy and that includes binary systems which may be more inhospitable to the evolution of complex life forms. Of the Sun-like stars that *have* been observed, there have been several "Solar analogs" which, though roughly similar to our Sun, differ significantly in terms of metalicity, temperature, etc. Only one true "Solar Twin" has yet been discovered. Not only that, but an unfortunate observation has also been made which seems to further dim the notion that our star is "average". As of now, no Sun-like star has *EVER* been observed to possess a disk of debris of as little density as our Sun's. Indeed, debris disks are usually found to contain many times the amount of material as ours. As far as disks of debris are concerned, our Sun does seem to be an unusual case. Comparing Earth history to other planets in this solar system is interesting but not very analytical. It is like saying to your girlfriend that she is the most beautiful girl in the room, when there are no others present. That analogy is a bit dishonest...because there *are* others present. The other planets in our solar system all developed through the same fundamental processes as ours. Some of these terrestrial worlds may or may not harbor or have harbored life as we know it in the same way Earth has, such as Mars, Europa, Titan, etc. Put another way; are all the mechanisms and events you state going to find parallels on other similar planets in other similar solar systems, thus making our evolution more or less typical? (Rhetorical question here.) Rhetorical or not, this very issue is the driving force behind the Rare Earth Theory (and the book which spawned it). Many are finding the arguments behind this theory tough to counter. As the kids like to text each other: OMG! I have no idea who I am responding to, but I’m beginning to wonder why I am bothering. Perhaps you have had too much RedBull or some such to structure a reasonable discourse. What was specifically said in my post that you found objectionable? My perspective is not based on technology as much as on basic physics. Unless we are dealing with gravity waves, neutrinos, or tachyons beams (being facetious here), our communication with or from ET will be based on the electromagnetic spectrum. That's reasonable and that's the basis behind SETI, but plenty of other reasonable people, including physicists, have speculated that ET might actually be more likely to use something like gravitational waves and neutrinos rather than the electromagnetic spectrum for a host of reasons, some of which have been discussed in other threads on this forum. My focus is with seti@home here. Piggyback scanning is one of the constraints of the experiment. That is fine. Each scan adds to seti’s observable universe. Just add it up as we go. When locations overlap, that is fine too. We can still state a number corresponding to seti’s observable universe. The spatial component will be in steradians, of course. The radial component (time component) will depend on the detector’s sensitivity at the time and so forth. So that is complex, but doable. I understand where you're coming from, but it seems to me that the fundamental issue is that I'm not sure that Aricebo's scanning across the sky is refined enough to quantify in terms of "how much of space" has been scanned. The SETI@Home star map view plots out detections across the visible sky, but since Aricebo is not doing point-by-point targeted scanning of every visible star, I doubt that this is of much use in telling us anything other than from what direction in space detections have been found. In order to be able to say anything concrete the way you seem to want to say it, I would imagine that star-by-star scanning would be required; ie, pointing the telescope specifically at each star within a certain distance from Earth... Just pointing Aricebo in their general direction wouldn't necessarily be good enough. And like I said before, even Seth Shostak has predicted that a thorough scan of enough stars in just our relative neighborhood would take a few decades. I hesitate to say yes to your offer, but others might find it interesting. If you do, please only list the publications in peer-reviewed professional journals, however. Anything less would be like quoting facts from the Internet or the New York Times: it just is not done in polite company. I agree, citing newspaper articles or stories on Yahoo or popular news sites doesn't really qualify, though if I claim a SETI scientist has said something I think it's fair to use articles he/she's written or interviews he/she's given. I've posted links to published research in various threads throughout the forum, but I'll gladly do so again here....but like I said before, I don't necessarily have a lot of time on my hands, so I might not post links to that published research too soon. |
Virtual Boss* Send message Joined: 4 May 08 Posts: 417 Credit: 6,440,287 RAC: 0 |
Billions of detections and hundreds of millions of work units have been processed. Personally I think that was a signal from ET - An intergalactic distress beacon on a spaceship travelling between Pisces and Aries ( or vice versa ). Think about it ..... 1) It "drifted in frequency" each time it was detected, as in Bleat, Bleat, Bleat, ...... 2) It is in the quiet band ( cosmic background radiation ) for maximum range. 3) It is in the so called "Water Hole Band" for a couple of reasons: a) They have civilisations in both the Pisces and Aries constellations, therefore are likely to be fishy sheep and/or sheepish fish in origin, both needing water holes to survive. b) They use Hydrogen as fuel and Hydroxyl derivatives ( Alchohol ) to numb their senses during the long voyages between constellations. 4) Because of 3b they probably overstocked the ship with hydroxyl and understocked in spare parts. 5) Also due to a combination of 3b and 4 they ( In their alchohlic induced stupor ) probably broke something important and either didn't have the parts or were too intoxicated to fix the problem anyway. 6) Due to 5 they are now ( or rather were ) bleating their sheepish distress in the hope that someone would come to their aid. Hopefully not everyone who detected their signals was unable to instantly realize the dire peril they were in ( Running low on hydroxyl supplies if not rescued ), rendering them at the mercy of intergalactic emptiness without any means of dulling the harsh reality. May they be ( either ) living ( or resting ) in peace. |
Dorphas Send message Joined: 16 May 99 Posts: 118 Credit: 8,007,247 RAC: 0 |
it all boils down to this..... in order to "find" something (et in seti's case) one first has to "look" for it (look at the data we have turned in..in seti's case). this is where seti falls flat on its face. but hopefully that will be fixed very soon.... |
Cory Workman Send message Joined: 15 May 99 Posts: 23 Credit: 360,462 RAC: 0 |
Yes it boils down to having to look to find something. but I think a larger part of the science is missing... We aren't sending a signal. There isn't enough research on how we would best send a signal if we WANTED to be found. Because we aren't trying. Only guesses exist... signals on the hydrogen line frequency... pulses to that it's obviously not natural... and in some mathmatical order. If just as much research was being done on what would be the best way to be found by sending a signal of some type as it was on trying to find what others may be sending, we might have a better chance of narrowing down what we are looking for. The project is promising, but I think there is an element to it that is kind of like cooking a great steak when you're a vegetarian trying to guess how the steak eaters like it done. |
Borgholio Send message Joined: 2 Aug 99 Posts: 654 Credit: 18,623,738 RAC: 45 |
One of the problems with sending a signal is return time. It could potentially take hundreds of years just for our signal to be heard, let alone responded to (assuming they even do). The best way to hunt for ET is in small steps. First scan part of the sky using Aricebo like we're currently doing, then expand to the rest of the sky. If nothing is found on current frequencies, then switch to new frequencies. If you still don't find anything then by that time it may be best to do a targeted search and just wait. You will be assimilated...bunghole! |
©2024 University of California
SETI@home and Astropulse are funded by grants from the National Science Foundation, NASA, and donations from SETI@home volunteers. AstroPulse is funded in part by the NSF through grant AST-0307956.