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

[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

[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.

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?

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

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