OK. Should I use 6 or 20 sided dice?

Furthermore, SETI has beneficial side-effects, such as providing employment for professional astronomers, it’s good PR for science in general (how many other scientific research projects could have pulled off what SETIStars just managed?) , and it helps fund infrastructure that can be used for other scientific research.

There’s literally dozens of other arguments for why it isn’t likely that we’d find anything; I don’t have time to list them all. For example, my rough estimates of the number of stars in a searchable radius failed to account for the fact that those objects are all in different stages of evolution. Presumably, a star’s age and spectral type affect the chance of it harboring life, so it’s not unreasonable to assume that those stars do not all have an equal chance of harboring life.

In short, I still maintain that no useful information is obtained.

We have a whole lot of evidence built up over how life started, and we can rule out a load of mechanisms as we have developed reasonable ideas of what the Earth was like and the laws of chemistry. If we find in half the sky no signals from an alien civilization it means the following: if they exist they are rare and beyond our radio horizon at those frequencies. They aren’t transmitting in something we listen for if they aren’t. Just those two things tell you that a) intelligent life is likely rarer than we’d like and b) nobody out of millions of possibilities uses radio, so IF we accept the Copernican principle that we aren’t special, and that *someone* out there would discover radio (the laws of physics being the same and all) it puts a lot of lower and upper bounds on the frequency and technological development of civilizations — certainly it tells you that there IS something special about using radio.

That’s a lot right there and someone with real radio data could tell more. I picked half the sky because that covers enough to know with reasonable certainty if anyone remotely like us is out there since they are just as likely to be in one direction as another. Just like if you look for a certain phenomenon and didn’t see it searching half the sky you would say your chances of finding it in the other half are reduced. Either way your problem is that much easier to solve, right? The parameter space for technological civilizations is huge, but it isn’t infinite. There are some things we can say for sure would be evidence. Find nothing, and that means that maybe life doesn’t form as easily as we thought, or at a minimum that it doesn’t develop interstellar-visible technology that often.

As for searching for alien beacons, I figure that if you were going to set one up you want to make it sufficiently similar to a natural phenomenon that other people would be likely to have set up equipment that studies the right kind of thing, and you choose a natural phenomenon that requires rapid measurements to get better bandwidth. Forget the water hole, I reckon alien beacons are more likely to resemble millisecond pulsars…

You say a null result tells you a lot. I’d argue that it tells you nothing at all, because you have no reason to suspect that a civilization would transmit what you are looking for. And why half the sky? What does that tell you if your other search parameters are arbitrary?

I wouldn’t call the Drake Equation ridiculous, as it is helpful in narrowing down the problem. And we do have accurate — or at least reasonable — values for the number of stars in the galaxy, and for the fraction of those with planets, and the average numbers with planets in the habitable zone. So that’s three so far. With the rest you can set your parameters. Since we know of at least one planet that has life on it, that’s a start. I’d say it’s no more daunting than discovering comets. There’s no directional information on where those come from either and you basically have to look at random for an object that appears for a few weeks.

And honestly, running a Deep Space Network-like set of radio dishes for a 10-year stretch covering the whole sky costs less than some individual companies spend on R&D in the same period. And in this case a null result would tell us a lot.

Of course, it could very well be that the average distance between civilizations is far enough that there is no possibility of detection or communication. But I would find it highly unlikely that there is no life whatsoever on any other planet, given the sheer number of stars. Intelligent creatures? Dunno. Maybe the path to mind is really wonky. Maybe the cultures that are like us (with an urge to explore and use up resources) kill themselves off. (I doubt the latter tho would have applied to *every* civilization).

I spoke to a few radio astronomers about it a while back. One thing they did say SETI is good for is training future people in the field. So in terms of efficiency you at least have that, along with the other real science that gets done in any case. And I admit a lot of what I think depends on what the exoplanet guys find int he next few years.

I know that there is still lots of unexplored parameter space left for SETI. But that was part of my point. You have no reason to suspect that these passbands would be used by aliens. You have no directional information. The physical range that they could look for signals in is highly limited. And why would an omnidirectional signal be used anyway? The power requirements would be stupidly huge. And a directional one has even worse odds.

And I know that “real science” is done at ATA as well. It was, for example, kinda a SKA test case, which is good and important. But it really doesn’t do *that* much compared to other facilities at this point.

I’m not saying that it’s *bad* to have SETI going, I’m just saying it’s probably not an efficient use of funds or talent compared to any of a myriad of other projects.

If anything, I think the most important point of this story is that maybe scientists, if their project is of the right sort, need to get better at leveraging private funds directly, and that this mode of funding may be more feasible in this day and age as compared to a couple decades ago. Maybe scientists should be using Kickstarter.com in addition to writing grant proposals.

Not really. We had precise math to predict its existence, and knew we could build equipment to directly search for the Higgs. We knew we could get an answer, and gain important knowledge from both a positive and negative outcome. Winning.

With SETI we have the ridiculous Drake Equation (with several variables that cannot be given remotely accurate values) and no clue in the world what aliens might be using for communication signals, or what equipment and frequencies are best to use. Kinda derp.

At a basic level, artificial signals tend to be relatively narrowband versus signals of natural origin. The fundamental nature of information leads to this, so even signals from a completely alien civilization should follow suit.

Information Theory has many concepts should allow very smeared, complicated artificial signals to be differentiated from random noise.

On the other hand, things like data compression and spread spectrum and other advancements in comm theory cause signals to become more noise like to an observer without knowledge of the data structures, modulation format, etc. The whole *point* of spread spectrum techniques is *not* to be detected by an outsider.

Would it be possible, given our current technology, to detect us (Earth), from lets say a distance of 50 light-years or so? What kind of signals are we sending into space?

Other than a few directed signals, like the one sent out at Arecibo, most of what we broadcast is not intentionally directed at space. Satcom uplinks would be the exception, I suppose, but they are actually pretty low power relative to a terrestrial broadcast station.

Honestly, I wouldn’t expect to pick up much past the nearest stars using SETI level equipment, if that, and I’m assuming a Manhattan Project level attempt with huge resources. We need the Deep Space Network and some of the most powerful error correcting codes ever devised just to get signals back from our interplanetary probes that are deliberately aiming at the Earth.

This is why I don’t put much stock in the Fermi paradox.

Right now we’ve looked at only a tiny fraction of the sky and in a relatively narrow band. If we look at half the sky and see nothing over a wider bandwidth that’s one thing, but we’re nowhere near that yet. Arecibo can only see a tiny bit at one time. The early searches, we know now, wouldn’t have seen anything. I had the opportunity to talk to Gregory Benford about it, and he mentioned that part of the problem is that leaky TV transmissions (from us) wouldn’t go all that far before the signal fuzzed out. Same is true for ET.

Really, to do it right you’d want a small-ish dish on the lunar farside. That isn’t going to happen right now, so you make do and try to cover as much ground as possible.

From my limited point view, I don’t even know if is possible to find an alien intelligence or recognize them for what they are, if you did.

Would it be possible, given our current technology, to detect us (Earth), from lets say a distance of 50 light-years or so? What kind of signals are we sending into space?

I’m not the sharpest crayon in the box, but it seems to me that when you have dozens of dishes scanning the sky, you’re bound to find a lot of neat stuff; even if it’s not what you’re looking for. Why not scan systems that have known planets, to try to determine the habitability of them? Or do some number-crunching for the Kepler project? Trying to find signals is all well and good, but there’s so much more in the realm of “extraterrestrial life” that falls under the less science-fictiony banners.

Yes, let’s not forget.

The problem is that with radio we can only look out to a certain radius before any signals are attenuated down into the noise, so there is a finite sphere that can be searched with any hope of finding a signal. You’re dealing with an inverse square law. Off the top of my head I’d say 100 LY max.

You might also detect some sort of laser comm array within a star system, but the alignment requirements there are even tighter, and as far as I know SETI has never gone beyond the proposal stage for such a search. I don’t think you’d get past that 100 LY limit trying to pick out a laser emission against the output of a system’s star.

Beyond that we’d need to be in the main lobe of a powerful and focused signal that was sent our way either deliberately or by luck of alignment.

Outside of all that, I dunno… search for indications of Type II and III civilization activity, I suppose, that’s visible and obvious over interstellar distances..

It’s hard to give any credence to arguments about how much it costs to run SETI when those arguments are made without facts in hand. No matter the cost, I hope the public is willing and able to step up and keep SETI running. Given the government’s recent tendencies toward decreased funding for science and science divisions in the government, it’s hard to envision a rosy future for government funding.

It’s also hard to rationalize the idea that years of null results in terms of finding intelligent life elsewhere is reason enough to stop something like SETI. Already, SETI@home has added a new application, Astropulse to look for a different type of signals, in a different way. This app not only looks for ET but also looks for other short pulse phenomena (exploding black holes, rotating pulsars, and the like) using the same data sets that SETI@home uses. Also, let’s not forget how amazingly large, how incomprehensibly huge (think of the volume to search) the Universe is and how vanishingly small any world bearing intelligent life would be compared to the volume of the Universe. Imagine how weak any signal generated by sentient life might be by the time it reached Earth. Finding a needle in a haystack is child’s play compared to any such signals that we might look for.

Nature imitating Art?