

Optical SETI 116
R3 writes "BBC News is running this story, about SETI's renewed efforts to find ETs who might be flashing us with light, instead of radio-waves:"
How many NASA managers does it take to screw in a lightbulb? "That's a known problem... don't worry about it."
You are so full of it. (Score:1)
Kind of telling, considering the moderators around here are barely literate.
different wavelengths, different properties (Score:1)
Re:What known source in space gives off laser beam (Score:1)
Which is, in reality, pretty stupid.
In space all you'd have to do is to punch a hole in the hull of the enemy vessel. The most effective way to do that is to shoot something hard and fast against it. A gatling gun would be much more devastating weapon than a silly laser beam.
Drug mysticism (Score:1)
You people seem to believe that because the imagery is similar from one person to another, it must mean something. Well, you're partially right. It means that human brain works in the same way in everyone. In other words, if Jack and Jill take the same amount of the same hallucinogenic drug, they're bound to have similar dream imagery. Alcoholics who are having delirium tremensis are known to hallucinate about snakes, insects and small, grey people. According to your logic, these should be real because so many people share the same hallucination. Bollocks.
As far as "expanding the mind" goes, you're only expanding the empty space in your head.
hah (Score:3)
Re:optical detection sounds hard (Score:1)
> a circle, not a sphere.
True enough. And even multiple lasers all up the mountain at different angles wouldn't help us here (imagine they're aimed 1 degree of arc apart, there'd be huge gaps between them at the range you're talking about).
> How long would Earth stay in such a beam?
Yeah, I missed that
Of course, if they manage to modulate their sun's output, we'd see that... And this is being considered by some SETI enthusiasts, just as Dyson Spheres are. If you alternately dim & brighten the sun's output in a clearly non-natural way, that's a good sign of intelligence. Just don't ask me how to do it - ask your local science fiction author!
Mark
Keeper of the Wedding Shenanigans Home Page
Re:optical detection sounds hard (Score:5)
> the other civilization know that we are right
> here, and that we are able to pick up their
> signals?
Yes, that's true if we assume they're trying to contact US specifically. If they've just got a huge laser on the top of their local Everest-sized mountain & are relying on their planet's rotation to turn it into a beacon we have a better chance of spotting it.
If we try to pick up radio we can (in theory) spot their TV signals, satellite communications & Star Wars ABM radars
> No matter what kind of transmission ET is using
> he will have to hope that we are able to pick
> up the signals
Of course - and that's why the Seti League (http://www.setileague.org/) advocate lots of smaller dishes. Their argument is that while an Arecibo size dish can look further, this comes at the cost of seeing a smaller area of the sky. Their favourite statistic is 'even if we're looking on the right frequency at the right time, there's a 99.999% chance that when the call comes in, we'll be looking the wrong way'.
Of course, they're talking about radio waves, but the same argument holds for optical SETI.
Mark
Keeper of the Wedding Shenanigans Home Page
Re:Inverse Square Law (Score:2)
Wouldn't the inverse square law save us? (Score:2)
Go you big red fire engine!
Aliens read "Ask Slashdot" ? (Score:1)
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Laser beams do spread out. (Score:2)
Your laser beam diffracts as it passes through any finite-sized aperture (the laser mirrors count as apertures for this). This causes the resulting beam to diverge (think back to the single-slit diffraction experiment in high school physics class).
A diverging beam can be thought of as a cone. The area of a cone's cross-section goes up as the square of the distance from the origin, so the intensity of the laser light will indeed go down as the inverse square. In a real laser beam, the distribution vs. angle is gaussian instead of uniform, but the same principle applies.
Using a wider beam would result in a narrower cone, but your aperture would have to be at least 10 km wide to have a spot size as small as a planet at a distance of 10 light-years. So, any practical laser would spread out like a cone that covers a lot more area than the target.
Re:How do ET aim at a moving target? (Score:3)
Short answer: Yes, but it would be expensive.
Long answer:
Stars and planets have (relatively) easily-plotted courses. Spend a few months with a big telescope, and you can do any fine-tuning you need to in your model of the planet or parent star's trajectory. Put a big beam splitter in front of the telescope, fire a huge, very expensive laser at the beam splitter, and you can send the laser beam to the target system while using the telescope to make sure it's going in the right direction.
Target _system_?
Well, the problem is that your laser's aperture is small enough that diffraction prevents you from focusing it on something as small as a planet over interstellar distances. So you'll probably end up bathing most of the inner system of the destination star in weak laser light. Your laser has to be quite bright to be picked up (even if you pulse it), which means very, very expensive.
Alternatively, you can build an array of many lasers in space, and pull evil tricks to keep them all in phase with each other. This gives you a very large synthetic aperture, which would let you target the laser at a single planet. Of course, you'd need a synthetic aperture optical telescope of comparable size to _track_ the planet, but if you can build the laser, the telescope is within reach also.
This is "stupidly expensive", as opposed to merely "insanely expensive", but it could be done. We'd have to do something similar if we wanted to easily launch sailcraft over interstellar distances.
Re:Accuracy (Score:1)
I see the lack of communication passing through our galaxy as evidence that we simply haven't figured out THE practical medium for communication. Maybe laser pulses for a billionth of a second are exactly how civilizations are communicating. The chances of there not being intelligent life elsewhere in the galaxy are just too small. If we determine this, then I'm going back to church.
Re:hah (Score:2)
Re:SETI is against intergalactic law (Score:1)
And, we'd also like to build a bypass.
DTV Codec (Score:1)
huh ? (Score:1)
Re:Accuracy (Score:1)
Ok, we do not know how to make a supernova send informative data, but we don't know either how to transform good old Sun into a supernova
Re:"Alien" Life (Score:1)
Well, please try none of these experiments and concentrate on praticing relationships with your beloved
Re:I dunno.. (Score:2)
You'd also take into account the fact that your planet moves, if indeed it does in your frame of reference. There is no such thing as being stationary in space (i.e. there exists no absolute velocity, Mr. Michelson), and in any case an advanced alien civilization or a high school student would be smart enough to calculate the direction of a laser beam as a function of relative locations. Given reasonably precise astronomical tools (beyond what we have currently built AFAIK but IANAA) it shouldn't be hard to figure out from a reasonably distant solar system that the third planet around our star revolves through a certain orbit, and that our star is moving through the galaxy with a certain velocity relative to the alien body. Yes, that body might indeed rotate, but if the transmitter were actually on the surface it would be simple enough not to broadcast when the target body is beyond the horizon... or use multiple transmitters, or just launch the transmitter into orbit. If the aliens really were so dumb as to not figure that out, would we really want to communicate with them? They'd probably be OS zealots anyway, or maybe just wanting to sue Adobe for using their patented ROT13 encryption.
Now suppose that within, say, 30 ly of Earth has picked up on our radio transmissions and has used some simple triangulation to figure out that our planet is the source of these transmissions. If they wanted to make contact with us, they could send us a message encoded in a laser beam. Yes, they might have to do some simple math, but I think they could do it. And that beam, if it exists, could be visible today.
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Re:hah (Score:2)
I don't think the point is whether the aliens are still there, but whether they were there at all. The other idea is that the signal may not have to have travelled all the way from another system, but may be broadcast locally by travellers.
Re:Inverse Square Law (Score:1)
In practice, a laser is formed by the photons which happen to bounce back and forth between two mirrors (a miniscule percent leaks through the beam mirror to create the usable beam). In most designs, photons going in other directions may contribute to the energy level but will not themselves emerge in the beam.
The geometry for a photon-as-a-particle requires the largest divergence angle to be from a photon which begins travel toward one edge of a mirror, and bounces between the mirrors umpteen times before escaping at the opposite edge of the mirror. Basically, draw a line from one side of one mirror to the opposing side of the other mirror, and that's the maximum for a photon with one pass at both mirrors. Most photons have to bounce back and forth a huge number of times, so the angle has to be much smaller in order for the photon to bounce back and forth "enough" times. Photons at too large an angle hit the wall and never come out as the beam.
Photon-as-a-wave doesn't use the same line-drawing geometry, but the above shows why the beam is narrow and the photons are nearly parallel. There are other effects due to the lasing medium and optics outside the lasing chamber.
Inverse Square Law (Score:3)
radioWaves.contains(light) ? (Score:1)
Using patters of light to indicate intelligence? (Score:3)
They're called pulsars.
SETI (really CETI) searches will fail (Score:1)
Advanced technological civilizations do not communicate across interstellar distances because you can never get off the first page of Encyclopedia Galactica. This discussed more in my paper from the OSETI III conference, Life at the limits of physical laws [aeiveos.com] which is part of the Matrioshka Brains [aeiveos.com] papers.
We can conduct "SETI" (where the emphasis is searching for 'signs' of advanced technological civilizations) but it requires gravitational microlensing studies, infrared and occultation astronomy -- not listening for radio or optical transmissions.
Re:A small gripe... (Score:1)
"Alien" Life (Score:1)
The scope of vision for most people when contemplating alien life is woefully narrow. Would our ancestors succeed in contacting alien life through smoke signals and drums? (maybe)
Nothing contradicts the possibility that hyper-advanced beings could manipulate the universe at will, perhaps even modify or conjoin with the fabric of the universe. Our bodys and minds are made up of this fabric, so is it really so far fetched to look within our selves to contact other beings?
In fact, some people believe they have already contacted [erowid.org] alien beings through the use of the hallucinogen tryptomanes, like DMT and Psilocybin (mushrooms). A large percentage of DMT "travellers" all experience the same contact with elf-like beings that can control the nature of reality. Some also believe that they have contacted [erowid.org] insect like beings through the use of psychedelic mushrooms.
Psychedelic research has a number of distinct advantages over SETI, though I am not saying that the SETI work should stop. First, it's cheap. Psychedelics are available to most people, if they try to find them. Also, hallucinogens get results, and they are testable, if you have the mental stability to handle the large doses required. If you don't believe it, you can try it. And, they also have the capability to expand your mind in ways unimaginable.
LS
Re:Drug mysticism (Score:2)
LS
Re:Drug mysticism (Score:2)
You're looking at the syntax of my words, and not the meaning. Perhaps I should have said "aware" instead of real. But doesn't the beginning of my statement, that no one has an unshakeable foundation of truth, mean essentially what you are saying?
I post in all seriousness about a touchy subject, and get modded down as flamebait and only ACs respond. Fuck, I hate anonymous cowards...
Re:So in summary (Score:1)
Great! (Score:2)
Shouldn't we better start to emit that kind of laser beams ourselves? In case another civilization has a similar kind of SETI project running?
I mean, what are the chances of aliens sending exactly the kind of radiation we are detecting? How can we be sure they are sending any radiation at all?
Re: "directed right at us" (Score:1)
Re:hah (Score:3)
So we better stop those SETI type projects. Or else an alien ship might destroy the earth to punish us for violating their equivalent of the DMCA...
Re:radioWaves.contains(light) ? (Score:2)
So what's the answer? Is light a wave, or is light a flow of particles? Well, the bottom line is that it's neither one. Light is are you ready? a "quantum vector field." That phrase doesn't give you much of a mental picture, does it? I actually kind of know what a quantum vector field is, and it doesn't give me any mental picture. The fact is that the true nature of light defies mental picturing, because it's not quite like anything we can lay our hands on. Under certain conditions, such as when we shine it through narrow slits and look at the result, it behaves as only a wave can. Under other conditions, such as when we shine it on a metal and examine the spray of electrons that comes off, light behaves as only particles can. This multiple personality of light is referred to as "wave-particle duality." Light behaves as a wave, or as particles, depending on what we do with it, and what we try to observe. And it's wave-particle duality that lies at the heart of the Heisenberg uncertainty principle.
When are we going to detect GRAVITY waves? (Score:1)
Gravity waves expand in all directions and don't dissipate in something as silly as an atmosphere or something. They can go on FOREVER! Wouldn't a really intelligent species be communicating with gravity?
OK, it's maybe a cheap plug for the LIGO project [caltech.edu], but can you blame me?
No, really, though, we should be looking at a multitude of sources for contact with intelligent life. Besides, according to Neuromancer, we've already picked up a bunch of signals from the 70s.
Re:I dunno.. (Score:1)
Laser light travels in a precise, straight line; it's not like a flashlight that beams an ambient cone of light..
Actually, lasers aren't all that straight. They get pretty "flashlightish" at long range.
Re:Just remebered - Ford Prefect (Score:1)
ID:4 Aliens all slap foreheads in unison (Score:2)
Just remebered - Ford Prefect (Score:2)
Don't have my copy of The Guide to hand though, so I can't verify this I'm afraid - anyone else know?
Re:Inverse Square Law (Score:2)
Don't think so (Score:3)
For example - take a laser pointer. Hold it about 30 cm (approx 1 foot) away from a surface and make a rough guess what sort of area the beam is covering. Let's say a circle with a 1mm radius to make things simple. Now stand 3m (about 10 feet) away. You're now 10 times as far away, and 10^2 is 100. Is the beam now hitting an area 100 times in size? Following the inverse square law, the area that the beam hits should go from about 3.1 square millimetres to 301 square millimetres (or 10mm radius). If it is then your laser pointer is broken.
I'm afraid I can't remember the physics of why lasers work this way, but they do.
Re:optical detection sounds hard (Score:2)
Erm, no. First of all, that laser beam would only sweep a circle, not a sphere. So unless we just happened to be exactly on the plane of their planet's rotation, we'd miss it. Secondly, even if we did happen to be lined up perfectly, we'd never notice it since the beam's path (not the photons) would sweep past Earth at a velocity far exceeding the speed of light. Consider that if they are 100 light years from us, then their laser would be painting a circle that is 2*Pi*100ly in circumference every one of their days. Assuming their day is the same as hours (24 hours), that would mean that at our distance their beam would be sweeping 70,000,000,000km a second. How long would Earth stay in such a beam? Not long enough for your detector to see more than a single photon. And that's assuming we just happen to be lined up.
No, the only way that laser communication would work is if it is directed straight at us.
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Re:Accuracy (Score:3)
Blowing up a star to say "Hello there!" (or "First post!", or "All your base...") seems like a rather expensive way to communicate. Plus you then have to travel to another star to send your next message.
Green Peace would have a cow if we started blowing up neighbouring stars for fun.
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Re:What the hell is wrong with the U.S.A.?! (Score:1)
regardless of how one feels about private gun ownership, I think we can all agree that this proposed bit of logic is seriously flawed, and reeks of hyperbole. I am reluctantly willing to agree that some european nations which ban small arms have managed to avoid sinking into despotism. Ordinary Gov't + Ban Small Arms+ time= Despotism : the corresponding argument of the 'gun nuts'. Neither argument is really true. You have to remember, the NRA is not really a secret society of evil child killers. That's just your propaganda. When you start to believe your own propaganda, that's really sad.
Not that this is anything but flamebait.
Funnny (Score:1)
Re:What known source in space gives off laser beam (Score:3)
Not so - there are natural lasers; all you need are the right conditions.
Examples from space: ultraviolet lasers [stsci.edu], Microwave lasers (masers) [achilles.net] and near infrared lasers [achilles.net].
If We Humans Are So Smart... (Score:1)
No wait! (Score:1)
Boy, that paragraph took a turn. I wonder were that came from? I guess I'll have to think about it when I ride my bike to work.
Thimk!
Re:Ridiculous (Score:1)
Mmmm....lets see our planet is 5 billion plus years old, millions of species have evolved, only one arose out of all that time to become sentient enough to be curious about the universe to engage in technology endeavors. 5 Billion years? Millions of species? Obviously this intelligence thing is a complete FLUKE, a one in a 5 billion years stab in the dark. Doesn't anyone find that odd? The chances of intelligence happening on another planet seems extremely remote too me given this evidence (or lack there of aka SETI.).
Your evidence to one or other direction is rather minimal; we have so far managed to detect just the first few tens of exoplanets that happen to be relatively near us and have very little knowledge about them; in practice, we know only our own solar system in any meaningful detail at all. That is not sufficient to analyze the situation galaxy-wide or even within the closest 100 lightyears IMO.
However, in the next few decades the situation might be changing with the planned projects that could actually be able to give us glimpses of the other worlds.
Re:optical detection sounds hard (Score:1)
Of course, the data requirements are high...
The "mini-supercomputer" mentioned above is, of course, a Beowulf cluster.Milalwi
Re:Are we intelligent? (Score:2)
Re:What's the usefulness of SETI@home? (Score:1)
Every UFO nut will say "Told you so", and abductions will become the new fashion.
Re:When are we going to detect GRAVITY waves? (Score:1)
Yay! (Score:1)
They're flashing us?? Hooray! Free alien pr0n!
*Grabs camera and dashes outside to take pictures of the sky*
Re:Just remebered - Ford Prefect (Score:1)
Moral of the story: always let people named after Ford Escorts (called a Ford Prefect in England) use your phone.
Re:Just remebered - Ford Prefect (Score:1)
Ridiculous (Score:1)
Using Lasers to send messages. How dorky.
Let me get this straight, a billion dollars later, a couple decades worth of enourmous computing power, and ZIPPO, no radio signals.
Now we are doing lasers?
Mmmm....lets see our planet is 5 billion plus years old, millions of species have evolved, only one arose out of all that time to become sentient enough to be curious about the universe to engage in technology endeavors.
5 Billion years? Millions of species? Obviously this intelligence thing is a complete FLUKE, a one in a 5 billion years stab in the dark.
Doesn't anyone find that odd?
In any case, most scientists believe there has to be many intelligent beings out there, yet they completely ignore the fact that we are IT on our own world and it NEVER happened previously!!
The one and only Darwinian trait, intelligence/technology arose in one and only one species in 5 BILLION years time, half the age of the know Universe!
There have been millions of species before us, that lived a lot longer and from all accounts of the fossil record and were a LOT more successful than homo sapiens. They didn't need intelligence either!
I think intelligence is so rare, that I am inclined to believe some of these spacemen stories that say we were visited and were modified in some way from domestic species. That seems much more likely given the fossil record.
The chances of intelligence happening on another planet seems extremely remote too me given this evidence (or lack there of aka SETI.).
Even if I do buy into the fact there is some intelligent civilization out there, they will have an understanding of physics, space and time that we as labratory rats can't possibly comprehend.
They most certainly won't be using Lasers or electromagnetic energy to communicate.
What is so dorky about the logic in this is that SETI admits that traveling to distant stars even at the speed of light would be impractical.
So what do they base there search on? The very impracticality of what they say can't be done!
Electromagnetic Radiation.
How STUPID.
hack
Re:hah (Score:3)
Sound's like "Mote in Gods eye" (Score:1)
Though they were not stupid enough to send a laser beam in small angle spotting just one measly starsystem just to contact someone else. (even though the manage to feed the laser for years!)
If you want to contact someone you'd better look for radio signals, anyone that can manipulate stars as a semaphore will probably decide for themselves whether they will come here or not. Btw, the aliens in the book used the laser to propel a large solar-sail vessel.
Accuracy (Score:1)
Kjella
Re:optical detection sounds hard (Score:2)
Or at least hope they take the time and effort to flash every star system within, say, a 50 light-year radius. But this strikes me as a specific example of a more general problem: our SETI efforts are directed towards detection rather than transmission; we seem to be doing a lot more listening than talking. If the aliens take the same attitude, then it's obvious no-one will ever contact anyone else.
Of course, a lot more effort is necessary for detection than for transmission, but AFAIK there aren't any transmissions going out specifically related to contact (our own EM noise probably doesn't count, simply because it doesn't have the oomph to travel interstellar distances). Are there any major efforts underway to ensure continuous transmission of "Hi there!" messages from good ol' Mother Terra?
Re:Accuracy (Score:1)
If the only tool you have is a hammer, you tend to see every problem as a nail.
Re:hah (Score:2)
Your first point illustrates nicely the difference between COMINT and ELINT. They don't have to be able to understand us to see that there is a message. If there is "noise" on a narrow waveband, it will be interesting in its own right. If there is noise on a whole group of narrow wavebands, that is very interesting.
Of greater concern is that all our comms will go over fibre and leave none to leak out into space.
Paul
Re:SETI is against intergalactic law (Score:2)
Just makes you think, though... What if they're using 1000 bit encryption on a scrambled frequency that changes every few nanoseconds... How would we ever detect them?
SETI is against intergalactic law (Score:3)
Earthlings:
This is the Intergalactic Police. Intercepting and attempted decoding of encoded signals is a violation of the Digital Milky Way Copyright Act (DMCA). This is a Class II Felony according in your sector according to Intergalactic Planetary Law.
We have your planet surrouned. You will agree to hand over all conspirators and contributors in this crime to our awaiting vessel.
We consider a conspirator or contributor to be:
If you do not respond and comply to this writ within 48 hours, your planet will be subject to immediate seizure for processing into raw materials according to Andromedean Law (ref. Victims of Crime Restitution Act, Article III, Section 2, Paragraph 500.23.
You have no chance to live. Make your time.
Re:What known source in space gives off laser beam (Score:3)
What known source in space gives off laser beams? (Score:1)
Like the subject says, what known source in space gives off laser beams? SETI searching for signals in RF and light is fairly well-known, and subsequently, those sources are well-documented. But... I honestly have never heard of anything in space giving off laser beams. I was hoping the article would at least mention an example, but it did not.
Anyone care to enlighten us/me?
Re:So in summary (Score:1)
And then, since light takes considerable time to travel from AlienWorld, and that planets, systems etc. are all moving, the place that the laser was sent from is almost certainly not where the planet is now, and it's tough to accurately predict the current location of a planet when you can't be sure how far away it actually is.
No, I think that the Intergalactic Destructo Missiles(tm) would probably head off into space and hit some poor sap who was just looking for radio waves. And then wouldn't your face be red!
Re:So in summary (Score:1)
You're also assuming that Lord High Master Gjo'rgW hasn't forseen your attack, and implemented the Son of GalacticWars program.
Re:So in summary (Score:1)
But my point was that it's only going to one place, since it's essentially a line from 'them' to 'us'.
Re:So in summary (Score:1)
So if the emittor was a foot wide, and your assumption came from the idea that it was a meter (for all the nasa fans out there), any distance estimate is going to be lightyears off.
And I'm not sure that what you're talking about is triangulation, either. Triangulation is measuring the signal strength from a transmitter at three points, and calculating from that the grid coordinates. The signal strength is a measure of the distance. What you're trying to do is calculate the distance to the source from several points, and I'm not convinced that this method could work. Maybe something to do with redshift...
Either way, I agree that it's rather pointless (although the idea of our sublight missiles hitting this poor planet a thousand years after we've become allies is rather amusing). Still, I'd have to think that firing a laser of high enough power to get that far at a planet could be considered a bit rude ("We come in peace, sorry about vapourising your lab").
So in summary (Score:3)
Re:SETI is against intergalactic law (Score:2)
What's the usefulness of SETI@home? (Score:1)
Re:hah (Score:2)
Re:So in summary (Score:1)
Re:I dunno.. (Score:1)
Re:So in summary (Score:1)
Re:So in summary (Score:1)
Not that this really matters. Anything sent to get there at sublight speeds will still be obsoleted by the FTL craft developed a few centuries later. Leading some poor, confused guidance program lightyears from home only to have it blown up and/or arrive years after first contact is just silly.
Light's light (Score:1)
Seems to me that if they're going to search for extraterrestrial light-based communications, they should be searching the entire spectrum--not just the groups of bandwidths into which we subdivide the spectrum.
Re:Just remebered - Ford Prefect (Score:1)
What, you don't have your copy of The Guide an you??? And I suppose you don't have a towel either?
Re:I dunno.. (Score:1)
And what is all this about having to send a beam the size of a planet?
optical detection sounds hard (Score:3)
It should be a lot easier to detect a laser beam directed directly towards the earth, than spotting a planet, but wouldn't we have to depend on the fact that the other civilization know that we are right here, and that we are able to pick up their signals?
No matter what kind of transmission ET is using he will have to hope that we are able to pick up the signals. For how long have we been able to pick up that kind of signals, fifty years, maybe. I don't think that the aliens would bother to communicate with such a primitive rase as the humans.
umm.. that was all for now. lunch time.
What if no one talks and everyone just listens.... (Score:1)
Re:I dunno.. (Score:1)
What is the logic of responding to a radio transmission with an optical one? Wouldn't it be much more promising to answer a call with the same technology? Of course they could but is it probable?
Re:hah (Score:1)
There are three strong source of radio emission in our solar system. The sun, of course, plus Jupiter and Earth. The sun's is typical of the emission in a quiet star. Jupiter's is what you would expect from a planet with an intense electromagnetic field, and it's Doppler shift has a periodicity of 5.2 years. Earth's emission is largely from mankind's technology and would show a Doppler shift of 1.0 years (of course).
As long as there is enough radio and tv transmission, the signals can be picked up. That they can't decode it won't mean a lot, that it can be detected as a radio spectrum that can't be explained by natural phenomena will make it worth a look-see.
Re:If We Humans Are So Smart... (Score:1)
Re:Funnny (Score:2)
Surface (or near-surface) dwelling beings would be exposed to a tremendous amount of 'visible' light. Most of the rest is either too long of a wavelength (infrared light just doesn't have the resolution of our visible wavelengths, never mind radio), or too short, and would either be filtered out by the atmosphere (UV and the higher wavelengths like Xray or gamma), or would kill anything with body chemistry similar to ours.
Someone did a paper on this a long while back, basically his conclusion was that the wavelengths that we call 'visible' light are just a natural result of our chemistry.
Besides, just imagine a primitive race that *could* see UV very well. It's not like they can just start a fire that produces copious amounts of UV radiation :)
Re:Ridiculous (Score:1)
Could you please tell more about what projects are planned that might reveal more about those exoplanets?
Accuracy (Score:3)
Why not look? (Score:1)
Re:I dunno.. (Score:1)
Damn, you mean aliens have to go through grant procedures too?
Miko O'Sullivan
I send you this first contact. . . . (Score:1)
Mr. Smith! We have confirmation of an extra-terrestrial signal!
Well? Can you decipher it?
It seems to be in. . . .
And?
It says "I send you this file so I may have your advice", sir. After that it just has this first_contact.doc file attached.
Damn! And we just installed outlook!
Yeah, I know it's a lame joke, but it had to be done.
Wait a minute! (Score:1)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Re:So in summary (Score:1)
Re:Funnny (Score:1)
How do ET aim at a moving target? (Score:3)
What do you think?
Are we (Terrans) currently able to target a laser beam on a planet 1, 10, 100 light years away?
I will fight for the right to be right
Difficulties with interference (Score:2)
For beings from another planet to contact us with focused optics, they cannot use a 'broadcast' approach (one source sent out to many users, a la radio stations). If they were trying to use a focused laser, this implies they'd have to know where we are in the first place (and would have known for the years the light had to travel)... or, if from far enough away, they would have had to sent the light to us before we existed!
I dunno, it seems to me that anyone out there would be far more likely to send a broadcast signal that finds us by chance, rather than a focused one, given the very short time we've had the technology to send/receive these sorts of communication. Thoughts?
Re:hah (Score:2)
I believe one of the rare occurences of Earth sending laser light into space was to measure the distance to the moon, using reflectors placed on it. So those beams didn't get very far (from an interstellar point of view).
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