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Seti@home pointless?

Almo said:
Not that I'm aware of... or radio astronomy wouldn't work very well.
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Then it is something else. Isn't this kind of communication highly directional and we could not pick up anything unless the communication was pointed directly at us?

But I still think I am right. As far as radio astronomy is concerned, this is a different kind of thing since we are talking about quality of signal not quantity of signal. Is RF signals reduced to noise after a few light years?
 
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Bill Thompson said:
Wasn't it determined that radio signals degrade after just a few light years?
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Bill Thompson said:
Then it is something else. Isn't this kind of communication highly directional and we could not pick up anything unless the communication was pointed directly at us?

But I still think I am right. As far as radio astronomy is concerned, this is a different kind of thing since we are talking about quality of signal not quantity of signal. Is RF signals reduced to noise after a few light years?
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If you ask the very same question enough times, in enough different ways, do you think the answer will be different?
 
If you really think that there is some simple fact about radio wave propagation that would make it impossible to detect after a few light-years of travel, why do you think there would be anyone interested in pursuing it? Granted that The Atheist (among others, of course) doesn't believe that it is worthy of spending any money on, his reasoning (nor the reasoning of any others that I know of) does not include any assumption that it is impossible due to problems in radio wave propagation. Of course, they could all (pro- and con- alike) be wrong, but if they are, then, as pointed out by Almo above, how does that reflect upon radio astronomy as a scientific pursuit?

No, it's not an argument. To fully understand this, look up electro-magnetic radiationWP propagation, properties of interstellar space for said radio propagationWP, and then you'll need to study some optimal receiver theory (http://adsabs.harvard.edu/abs/1979STIN...8018284L for example) in Electrical Engineering and Shannon's Information theoryWP.

Then it is something else. Isn't this kind of communication highly directional and we could not pick up anything unless the communication was pointed directly at us?
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No, directionality might make it work better, but almost all radio sources that radio astronomy studies are omnidirectional, and thus maximally weak, and they are still studied.

But I still think I am right. As far as radio astronomy is concerned, this is a different kind of thing since we are talking about quality of signal not quantity of signal. Is RF signals reduced to noise after a few light years?
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Nope, you're wrong. First, what do you mean by quality? Radio astronomers extract considerable information from the signals they receive (spectrum, polarization, all sorts of possible modulation techniques, etc, etc). Granted, they don't often look for, say, phase modulation because that isn't created by any known natural phenomena, but there is no known reason why such modulation should not be detectable over galactic distances if it was there. Radio is radio; if it is carrying information, it will not be the distance that matters but rather the cleverness of the SETI detection methods that may miss it.

Distance alone does not affect the signal-to-noise ratio of a radio signal, most particularly through a vacuum.

Finally, remember that radio is one form of EM radiation; others include light, infrared, ultraviolet. microwave, Xray and gamma rays. All propagate in exactly the same manner. In fact, a SETI civilization could use any one of them to signal us, as well as several other methods. The SETI people investigate radio mainly because it is not much affected by atmosphere.
 
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I think there is a point in the OP, though. Even with a radio telescope 100 times the sensitivity of Arecibo, we would not be able to detect our own broadband radio and TV leakage beyond our own solar system. Source.

SETI must be searching for a stronger, more directed (narrowband) signal.

BTW, best I can tell, none of this is about SETI@home in particular, right? It's just about SETI with radio telescopy in general. Nothing happens to degrade potential signals between the time they're received at Arecibo and the time they're divvied up and received by home participants, is there?
 
Bob Blaylock said:
If you ask the very same question enough times, in enough different ways, do you think the answer will be different?
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What? It was answered by people who have not thought it out and/or people who do not even know.

A response is not an answer. The response was not correct. The response was from people who are merely hopeful and not a scientist who knows this stuff.

Radio signals are a spectrum of light. Light is made of photons. While I have been looking on the web reading what others have said it has become clear that unless ET intentionally directs a powerful beam directly at us, we would not be able to distinguish a signal from them.

This is true for several reasons.

Here is one reason. Like I said, light is made of photon. As a signal goes out from its source traveling along the surface area of a sphere, how many photon are spread out along this surface area? (Surface Area of a Sphere = 4 pi r 2 ). Let me put this in perspective. People who like to believe that we have sent signals into space already that ET can hear and understand like to use 50 light years as an example and say that a star 50 light years away from us will have been picking up radio signals from us. Well, what they would have been listening to would be a degraded signal undistinguishable from the background radiation of space left over from the big bang because the photons from a 50 year old radio signal would be dispersed evenly on the surface area of a sphere the size of 31415.9 square light years. (Surface Area of a Sphere = 4 pi r 2 ) There is no way that an episode of "I Love Lucy" or the Olympics in Germany before World War II could be watched and enjoyed on a star system 50 light years away because the signal travels along a medium that would be too fragmented by the time it reached them.

Here is another reason. 50 light years is a long distance. Any radio signal traveling that distance would be subjected to the whatever is already in that area. I can think of several things that would influence the quality and integrity of a radio signal. The most influential would be the background radio noise left over from the Big Bang. a faint radio signal would merge with and be indistinguishable from such noise over time.

The Radio Telescope argument does not hold water. Radio Telescopes pick up signals from powerful objects like a star. Radio transmissions do not compare.
 
Bill Thompson said:
Radio signals are a spectrum of light. Light is made of photons. While I have been looking on the web reading what others have said it has become clear that unless ET intentionally directs a powerful beam directly at us, we would not be able to distinguish a signal from them.

This is true for several reasons.

Here is one reason. Like I said, light is made of photon. As a signal goes out from its source traveling along the surface area of a sphere, how many photon are spread out along this surface area? (Surface Area of a Sphere = 4 pi r 2 ). Let me put this in perspective. People who like to believe that we have sent signals into space already that ET can hear and understand like to use 50 light years as an example and say that a star 50 light years away from us will have been picking up radio signals from us. Well, what they would have been listening to would be a degraded signal undistinguishable from the background radiation of space left over from the big bang because the photons from a 50 year old radio signal would be dispersed evenly on the surface area of a sphere the size of 31415.9 square light years. (Surface Area of a Sphere = 4 pi r 2 ) There is no way that an episode of "I Love Lucy" or the Olympics in Germany before World War II could be watched and enjoyed on a star system 50 light years away because the signal travels along a medium that would be too fragmented by the time it reached them.

Here is another reason. 50 light years is a long distance. Any radio signal traveling that distance would be subjected to the whatever is already in that area. I can think of several things that would influence the quality and integrity of a radio signal. The most influential would be the background radio noise left over from the Big Bang. a faint radio signal would merge with and be indistinguishable from such noise over time.

The Radio Telescope argument does not hold water. Radio Telescopes pick up signals from powerful objects like a star. Radio transmissions do not compare.
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Yes this is correct. The only signal we are likely to 'read' would be a very tightly focused beam aimed directly at us from a very very powerful transmit ion source and then very unlikely to be further away that 100 ly
 
I watched a documentary on how fast the remains of human civilization would disappear if we all vanished in an instant, and one of the things they mentioned was that radio signals dissipate pretty fast. Of course, I don't know their sources, and TV documentaries have been going downhill lately.
 
Bill Thompson said:
What? It was answered by people who have not thought it out and/or people who do not even know.

A response is not an answer. The response was not correct. The response was from people who are merely hopeful and not a scientist who knows this stuff.

Radio signals are a spectrum of light. Light is made of photons. While I have been looking on the web reading what others have said it has become clear that unless ET intentionally directs a powerful beam directly at us, we would not be able to distinguish a signal from them.

This is true for several reasons.

Here is one reason. Like I said, light is made of photon. As a signal goes out from its source traveling along the surface area of a sphere, how many photon are spread out along this surface area? (Surface Area of a Sphere = 4 pi r 2 ). Let me put this in perspective. People who like to believe that we have sent signals into space already that ET can hear and understand like to use 50 light years as an example and say that a star 50 light years away from us will have been picking up radio signals from us. Well, what they would have been listening to would be a degraded signal undistinguishable from the background radiation of space left over from the big bang because the photons from a 50 year old radio signal would be dispersed evenly on the surface area of a sphere the size of 31415.9 square light years. (Surface Area of a Sphere = 4 pi r 2 ) There is no way that an episode of "I Love Lucy" or the Olympics in Germany before World War II could be watched and enjoyed on a star system 50 light years away because the signal travels along a medium that would be too fragmented by the time it reached them.

Here is another reason. 50 light years is a long distance. Any radio signal traveling that distance would be subjected to the whatever is already in that area. I can think of several things that would influence the quality and integrity of a radio signal. The most influential would be the background radio noise left over from the Big Bang. a faint radio signal would merge with and be indistinguishable from such noise over time.

The Radio Telescope argument does not hold water. Radio Telescopes pick up signals from powerful objects like a star. Radio transmissions do not compare.
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So your arguments are based solely on omnidirectional dispersement of the signal across a spherical surface, and the resulting signal-to-noise ratio. You say that radio astronomy arguments fail because they are looking at stars, not radio transmitters.

Suppose a directional signal is sent by an ET that has the directional brightness within a band of radio frequencies equivalent to that of a star. Is that impossible? Will it be impossible to our civilization within, say, another 5000 years of development (providing we don't get overwhelmed by the evangelists)?

Perhaps there is some limit on technology which we don't have an inkling about, and we'll hit a power ceiling in the next hundred years, so we may have only the 100 LY radius sphere mentioned by BonkingBear above. How many possibilities does that leave? Something in the rough area of 10000 stars, according to http://wiki.answers.com/Q/How_many_stars_within_50_light_years_from_earth. Is that enough to justify SETI? For a more complete justification, see http://www.bigear.org/vol1no1/kraus1.htm.
 
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10000 stars is probably not enough to justify SETI if it was tax payers money....but as its privately funded does it really matter. Personally I am pleased they are doing this work.....you just never know....we could be real lucky and there is another communicating intelligence somewhere on one of what may be some 50,000 planets. Even a negative result will tell us something.
 
If you consider that anyone out there intentionally beaming narrow band signals toward other stars would be at least as technologically advanced as we are and that we are currently developing systems to detect planets on which life is likely, then their similar technology would narrow down the range of planets to which the ET's must beam a signal. In other words, though we have tens or hundreds of thousands of stars to listen to, they might be able to narrow their broadcasts to mere hundreds (or fewer, assuming further advances in detection technology.)

I honestly don't expect SETI to find anything, but I can't say it's pointless. I really hope I'm wrong...
 
BonkingBear said:
Even a negative result will tell us something.
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Not much. Don't forget the transit time. If we don't get a signal when we point a telescope at a certain position, it only tells us that nobody sent a directed signal to us at the appropriate time in our past to be reaching us now.

Everything is so spread out in space and time, that even if there are a great number of technological civilizations in our galaxy, we may never know about them.
 
BonkingBear said:
Yes this is correct. The only signal we are likely to 'read' would be a very tightly focused beam aimed directly at us from a very very powerful transmit ion source and then very unlikely to be further away that 100 ly
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Then SETI @ Home is a huge waist of effort. No intelligence would ever pick us out of the billions to be important or worth any time or effort.

It is self evident. Our species was too stupid to know SETI @ Home was a waist of time.
 
Bill Thompson said:
Then SETI @ Home is a huge waist of effort. No intelligence would ever pick us out of the billions to be important or worth any time or effort.
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Nonsense! You're assuming that any intelligence making an effort being heard knows who it's sending to! That's woo territory.

The most "likely" scenario is that an alien intelligence would have detected Earth among other planets as a likely place for life (as we are currently trying to do with other starsystems). It would be plausible that efforts would be made to send radio signals Earths way.

Note to self: When insinuating stupidity in others at least make an effort to spell correctly...
 
JoeTheJuggler said:
Not much. Don't forget the transit time. If we don't get a signal when we point a telescope at a certain position, it only tells us that nobody sent a directed signal to us at the appropriate time in our past to be reaching us now.

Everything is so spread out in space and time, that even if there are a great number of technological civilizations in our galaxy, we may never know about them.
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I don't disagree - the problem is that despite all that we are discovering at the moment it only shows us how little we really know about the evolution of the galaxy and life in general.:)
 
I'm sort of in the SETI is futile, but not necessarily pointless, category. I'm leaning more to the terrestrial radio sources will be too dispersed to be detectable, side of the fence. But I would rather see money wasted on SETI that gives people some interesting hope and prospects for the future instead of governments wasting money on faith based initiatives or other BS policies that push us back in time.
It's like the first lunar landing. Mostly a pointless endeaver, but it excited the imagination and pushed the limits of what's possible.
 
A Bill Thompson thread on SETI!

This exact subject got him banned from the Bad Astronomy/Universe Today forum, just to warn you guys. He's that obstinate.
 
I do believe SETI@Home is pointless, but it has nothing to do with how valid SETI itself is as a project.
 
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