5X5 Episode 24

New strategy for SETI - The Search for ExtraTerrestrial Intelligence.
S: This is the SGU 5x5 and tonight's topic is: The search for extraterrestrial intelligence (SETI). Astronomers using radio waves to look for ETs that might be sending us signals have hit upon a new strategy, which is actually quite clever. What they're doing - or what they've thought of is, to look at other solar systems that might know that the earth is a life-bearing planet. Here's how the logic goes: if astronomers, alien astronomers, in other solar systems were investigating our solar system, if they were in a line with the ecliptic of our solar system, the plane of our solar system, they would be able to see the Earth when it passes in front of our Sun and doing spectral analysis they would be able to see that the earth has oxygen in its atmosphere. A planet with oxygen in its atmosphere almost certainly has life because oxygen is such a reactive compound– element, that it would react with other things and wouldn't be in a free form in the atmosphere. So, if the aliens in that plane could know that Earth had life on it, maybe they would choose to beam radio signals at the Earth to communicate with us. So that's where we should be looking for radio waves.

R: So, does this mean that before we were looking in places where they wouldn't know that we were here? That doesn't make sense.

S: It wasn't taken into consideration. We were looking either at globular clusters because it's a lot of stars all in one place, or we were just looking, just surveying the sky, the entire sky piece by piece. But this gives us a rationale for focusing our efforts in a place where there's this little extra added reason to think that aliens may be beaming radio signals to us.

B: I like how it's a way to make a subset of stars that we could investigate and maybe give them a reason to investigate us, but doesn't it assume that they have a technology similar to ours? Because it's definitely– it helps us if we can visualize another planet that's in our plane, because it's easier for us to see. But other civilizations, they could have telescopes that are thousands of times bigger and better than anything we have. They could– they would probably be able to directly visualize Earth-sized planets and do spectroscopic analysis. Isn't it just assuming that they are close to our level of technology when they necessarily aren't anywhere near us?

S: Well I think it's– it's not so much an assumption as a statement of probability. If we're focusing in this area where it's easier to tell that the Earth probably has life, that increases the probability that a radio-transmitting civilization would be pointing their radio transmitters in our direction. So it's probability, you know what I mean.

J: What do you guys think of the whole– the whole effort?

S: I think it's awesome.

R: It's alright.

(laughter)

B: I think the payout is so extraordinary, it's worth the meager effort that's going into it–

E: Right, plus it's plausible.

R: Yeah.

J: While they're doing it–

B:–even though it's low priority-

J: –are we still learning about the universe while they're doing that? I mean, is there– is it still adding to the library of knowledge?

E: Absolutely.

S: Is the SETI project itself adding to our knowledge?

E: How could it not?

S: Sure. It's still doing radio astronomy, it's still looking at the sky with a radio telescope. I think the effort is definitely worth it. It's– sometimes you just have to take a look. We could speculate endlessly about the probability of there being intelligent life elsewhere and the technology they would have, all trying to extrapolate from this single example we have on the Earth, or we could look and see if anything is out there. The thing that's interesting is at the beginning of the SETI project, they had no idea that if– when they turned the telescope to the sky, they would be instantly be bathed in multiple signals. They really had no idea.

B: Wow.

S: Now, of course, that's not the case. But we may point our telescope in the right direction and listen in with the right frequency and suddenly start hearing a one-way conversation with an alien intelligence. What would be more fascinating than that?

E: But I like how they've narrowed it down to the 3% of the sky that represents the ecliptic of the plane and they're actually doing higher probability calculations that this is– this is perhaps a fertile ground for finding something.

S: Yeah, I think it's clever. I think it's– anything we can use to limit the number of haystacks we have to start looking through–

B: Right.

S: –for the theoretical needle that might be there-

B: It's like–

S: –the better.

B: –it's like the– what is it? The hydrogen line, the frequency where it's pretty much–

S: Um-hmm

B: –dead in space and it's like an obvious hole to transmit in. It's kinda - it reminds me of that, where it's like oh yeah, that's an obvious way to broadcast, to look, and so the more that we– the more of those types of things we can find, the more chance you'll hit on a civilization that thought the same thing you did.

S: We think. Of course, we won't know until we find it.