Detection of Earth-like Civilizations in Space Now Possible

Mr. McGibby writes "Astronomers have come up with an improved method of looking for extraterrestrial life with an Earth-like civilization. Theorist Avi Loeb proposes to use instruments like the Low Frequency Demonstrator (LFD) of the Mileura Wide-Field Array (MWA), an Australian facility for radio astronomy currently under construction. The array could (theoretically) detect civilizations broadcasting in the same frequencies as our own society. From the article: 'Loeb and Zaldarriaga calculate that by staring at the sky for a month, the MWA-LFD could detect Earth-like radio signals from a distance of up to 30 light-years, which would encompass approximately 1,000 stars. More powerful broadcasts could be detected to even greater distances. Future observatories like the Square Kilometer Array could detect Earth-like broadcasts from 10 times farther away, which would encompass 100 million stars. ' The original paper describes the details."

Comments

Knowing Your Neighbours

[Renegade Lisp]

I think this is a great project. But step back for a moment and think what it means: If there was an earth-like civilization even very close to us, say, at Alpha Centauri, we've had no chance of detecting their stray radiation up until now. And with this new program, it's only within 30 light years that we might be successful. That's really our very, very close vicinity.

This, I think, puts the fact in perspective that SETI@home hasn't found any signal yet, even after years of listening. They would only be able to detect very powerful transmissions, much more powerful than anything our own civilization could produce.

The fact that we haven't found any artificial signals from space yet doesn't mean there's nobody out there.

Re:Knowing Your Neighbours

[oliverthered]

But that still means that there could be nothing out there
And he stretched out his noodly appendage

Re:Knowing Your Neighbours

[zippthorne]

Ridiculous. It depends on just how much evidence you don't have. For instance, there's very little evidence of the existence of Yeti despite some rather concerted efforts to find anything at all. In fact, there is no evidence at all. Yet mountain lions are easy to find evidence of. Therefore yeti are far less likely to exist than mountain lions.

Absence of evidence is prima facie evidence of absence.

The question is, does your lack of evidence result from failing to look or from nothing turning up despite exhaustive searching?

Re:Knowing Your Neighbours

[exp(pi*sqrt(163))]

For a slightly more formal treatment see here. Sagan was talking out of his ass when he said that and there's nothing more annoying than people who keep quoting it.

Re:Knowing Your Neighbours

[peragrin]

I forgot the name of the species of fish but scientists thought it to be extinct. For years the evidence pointed to the fact that the particular fish no longer existed, yet one day a fisherman caught one.

A lack of evidence either way doesn't mean it doesn't exist. There are numerous example of animals that hide first. The possum "plays" dead. An animal intelligent enough to hide from other species isn't unheard of. Given the right locations on earth, two mountainous and relatively uninhabited area's. It is possible a yeti, and big foot exist.

of course that being said I won't believe it until I see it, but that doesn't mean it's impossible, just improbable. That's a huge difference.

Re:Knowing Your Neighbours

[JavaLord]

that assumes they want to find us, or even find us worthy of contact. They may have found us already, reported back to their homeworld, and decided we're not worth their time to look at, maybe we're too far, (could take them a long time to get here) could be we don't (didn't) have a sufficiently advanced civlization. And heck if the probe took 250,000 years to find us, who's to say that the originating civilization hasn't given up, or disappeared, died out, sun went nova? who knows. and if it takes 500,000 years to search the galaxy, well, human civilization hasn't been around for nearly that long, we could have been one fo the first looked at 500,000 years ago, and found to be inhabited by all kinds of animals.

The other thing funny about assuming things about our hypothetical aliens is that we assume they have our same lifespan. While 250,000 years is a long time to us, maybe it's only a few generations to them? Or maybe it's much longer to them and they have lifespans of only 10 years....It's just impossible to know these things, but it's fun to speculate.

Re:Knowing Your Neighbours

[HiThere]

Well, the lifespan has to be approximately right. It could be longer, but much shorter and there isn't that much reason to evolve intelligence. Mind you, if they run their bodies hotter or colder this is subject to variation. (Chemical reaction speed being thermally determined.)

If their lifespan is longer, one needs to wonder what part of their lifespan is longer? Childhood or adult? It would make a big difference as to their nature. Long childhood would lead to more flexible thinkers. Long adult would lead to great emphasis on stability (presuming both adults were charged with rearing the children). OTOH, if intelligence were a sex linked display, like a peacock's tail, IP would be EXTREMELY jealously protected...and the non-displaying sex would be relatively (grossly?) stupid.

A large part of what we are is determined by evolving in small groups of individuals who were close kin to each other. Without this we probably wouldn't have evolved altruism or mercy. It's still rather unreliable, but we exhibit more of it than almost any other animal. As it is, it is sufficient to enable us to evolve rather complex societies. (We *do* need to keep a constant eye out to prevent cheaters. [Mr. Gates.] But this is the expected result from game-theoretic simulations.)

Do we assume the same thing for aliens? How else could you evolve a planetary civilization? Is THAT the answer to Fermi's paradox? ("Where is everybody?")

Re:Knowing Your Neighbours

[theTerribleRobbo]

And to quote Carl Sagan, "Absence of evidence is not evidence of absence."

Carl Sagan has obviously never had to deal with a HR department.

Not a big area

[Orange Crush]

30 or even 300 LY is tiny on a galactic scale. Then again, anybody who's more than 30 ly away won't be able to have a meaningful conversation with us over the course of a single researcher's lifetime . . . unless of course they're kind enough to send instructions on how to communicate FTL.

Speaking of FTL communications . . . maybe civilizations only use radio for a relatively short time in their development. Present understanding of physics pretty much rules out FTL communications, but there could always be some exotic aspect of our universe we haven't discovered yet that would allow it and we'll finally be able to log in to the giant IRC server of the universe.

Re:Not a big area

[David_Shultz]

anybody who's more than 30 ly away won't be able to have a meaningful conversation with us over the course of a single researcher's lifetime

Are you joking? Do you not think it would be meaningful just to receive the message "hello"? this would be one of the most important moments in the history of humankind (not to mention alienkind). A long conversation isn't needed for this to be meaningful. Heck, no conversation is required -we just want to find someone else out there.

What does "Earth like" mean?

[soft_guy]

Would this method have detected our civilization in the 1800s? 1910? 1930? 1950?

What exactly is it detecting? FM radio? Television? Radar? Emissions from cars? Would it detect a working telegraph?

Re:What does "Earth like" mean?

[sentientbeing]

On Earth, its more likely the lower frequency fields radiated by all the mains cabling and power sources that would be easier to detect.

Re:Hmm.

[MindStalker]

Exactly, though its a given that if an alien civilization more advanced than use WANTED to be found they would use multiple technologies radio being one of those. Radio would most likely be a baseline technology that any advanced civilization capable of interstellar communication would have already reached.

Fiber to the Home.

[crhylove]

Unless alien civilizations are just as beholden to corporate interests and backward technology as we are (which I doubt, and if it is the case why should we bother communicating with their ignorant asses anyway?), I would assume their civilization has fiber to the home, and I doubt their wireless controllers, cell phones, and remote controls are going to have a signal that gets off the planet at all.

If we were REALLY interested in contacting alien civilizations, we would make our own much more attractive first. I doubt any alien civilization is going to be interested in sharing technology with a planet of retarded monkeys that give morons like Bush who openly admit talking to invisible men in the sky nuclear weapons.

As a matter of fact, I can't imagine any advanced civilization bothering with the kooks who live here and believe in such ludicrous stone age fantasies. Particularly kooks with nuclear weapons and who engage in water-boarding.

I'm so ashamed of our whole species I can't even begin to imagine why *I* bother interacting with them, much less some aliens who weren't so unlucky as to be born in this idiotic power-structure of ignorance.

rhY

Re:Fiber to the Home.

[Simetrical]

You're using a definition of "advanced" rather at odds with what everyone else here means by "advanced". We're all talking about technologically advanced, whereas you seem to be talking about morally advanced. But that seems like an odd thing to expect of aliens in any case: surely their morals would be dramatically different from ours?

It seems strange to expect that very many aliens would disapprove of torture, for instance. Why would they? We haven't, up until perhaps fifty to a hundred years ago. You can make a convincing Machiavellian argument that the ends justify the means and a few probable (even if not certain) terrorists' suffering is justified. That kind of argument is mostly out of favor now, but I very much doubt it would be if we were, say, ants.

Aliens

[darknite1979]

I think it would be foolish too assume that we are the only life in the universe. The problem with finding life is that we really dont know how common life is in the universe. I recently saw a website http://www.anzwers.org/free/universe/index.html that can give very good perspective on just how big the universe reaaly is. Either an alien species has already detected us and is waiting for the human race to cause its own extinction (which I am sad too say is likely at this point) or they are so advanced that they reaaly dont care about us in any way.

intelligent life on earth?

[peter303]

From the way be behave, I wonder.
Remember Star Trek IV when the aliens though just the marine mammals were intelligent.

Optical SETI is the way to go

[TheSync]

Optical SETI with intense nanosecond light pulses is the way to go, forget radio!

1. Visible light-emitting and detecting devices are smaller and lighter than microwave or radio-emitting devices.

2. Visible light-emitting devices produce higher bandwidths and can consequently send information much faster.

3. Interference from natural sources of microwaves is more common than from visible sources.

4. Naturally occurring nanosecond pulses of light are mostly likely nonexistent.

5. Existing lasers can produce nanosecond pulses that can outshine a star by 30 times.

http://observatory.princeton.edu/oseti/oseti.html

A long, boring, convoluted logical argument

[duh P3rf3ss3r]

You are exactly right and I can't believe all of the people who are just so wrong on this.

It's very much like this.

Joe: All swans are white.
Jill: What evidence do you have?
Joe: I saw a swan and it was white, hence, all swans are white.

Any of us looking at this would see that Joe's assertion is unproven. The absence of a non-white swan in Joe's search is not proof that non-white swans are absent, if you'll pardon my tortured language for illustrations's sake. Now:

Joe: All swans are white.
Jill: What evidence do you have?
Joe: I've inventoried 1000000 distinct, separate and individual swans and each and every one of them was white, hence, all swans are white.

Now, there are those among you who would feel that Joe's conclusion in this second scenario is better supported (i.e. more evidence) but that's simply false. The only evidence that Joe has amassed is that, within the space Joe has searched and during the period of his search, white swans certainly out-number non-white swans. Joe has come no closer whatever to evidence that all swans are white because, in both the first and second scenarios, finding just one non-white swan invalidates Joe's hypothesis.

Hence, an absence of evidence as to the existence of non-white swans is not evidence of the absence of non-white swans. It is always possible that the next swan Joe examines from the pond across the hill will be a non-white swan and it will invalidate Joe's hypothesis in one fell swoop. It doesn't matter whether Joe has examined one swan or one million swans, such is the case.

Now, there may come a time when Joe has entirely (or practically) exhausted the available search space (e.g. looked at each and every swan on the planet.) What then? Well, then we may be tempted to argue, and many might agree that, once the reasonable search space has been exhausted, Joe can say that absence of evidence is evidence of absence.

For those of you who think this message is already far too long, perhaps we can agree to stop here and, for practical purposes, stipulate to that. But, by any measure, the reasonable search space for ET is far from exhausted. In fact, at this stage, we are very much like Joe when he had examined just one swan and tried to use that as evidence that all swans are white. Hence, I maintain that Sagan's statement, applied to SETI, is logically flawless.

Now, if there is anyone out there who's bizarre enough to be enjoying this, let's examine the case of where Joe has exhausted the reasonable search space for swans and has still failed to find a non-white swan. Is this evidence that all swans are white? Well, in reality, no. It certainly suggests that non-white swans are exceedingly rare in comparison to white swans. But there is always the possibility that there will be a very rare recessive gene or perhaps a random mutation that will produce a non-white swan tomorrow within the space that Joe has already searched. Hence the absence of evidence for non-white swans proves absolutely nothing -- nothing -- in any rigourous sense, about the absence of non-white swans.

That's why scientists are trained to avoid forming hypotheses like "all swans are white" because that statement is, essentially, unprovable and unprovable can logically be shown to be functionally equivalent to unfalsifiable.

A better hypothesis would be something along the lines of: "In a random sample of 100 (or 1000 or whatever number the granting agency gave you a budget for) swans, the incidence of non-white swans will not be significantly different from zero (or less than 1% or 5% or whatever number you think you need to specify in order to secure the grant.)"

QED