This is the part that I figured probably has the most relevance to the slashdot crowd:
SETI@home
"I think it's just the open-face fish sandwiches that everybody wants."
Siduri: So what's the relationship between the SETI Institute and SETI@home?
Seth: Cordial. Well, there aren't many SETI experiments in the world. To begin they figure SETI's all one giant organization, which it's not. SETI's just an acronym. There are a half a dozen SETI experiments going on. But in terms of radio SETI, the big ones are right here in the Bay Area. What the Berkeley guys do, they're just two guys.
Siduri: So there's no formal relationship.
[Seth ]
This is Seth's telescope, but sometimes
he lets other people drive it
Seth: Well, we support them, we give them a bit of money, because we know these guys. But it's a different experiment. What they do?I'll tell you what they do, because it's pretty interesting. If you look up you can see there, [pointing to a photograph] you see the way this thing works, which is that there's a big reflector: the radio waves come in, they bounce off, and they go into here, this buckyball [there's a bit I can't make out here; Seth is facing away from the tape recorder] boink boink, and then into the receiver. So that's what we're using. By moving this thing around on these tracks, we can point to anywhere within 20 degrees of the receiver, and then you just wait for the Earth to rotate. You get a lot of the sky with this thing. And then this telescope is pointed straight up and you can actually see... [voice trails off as Seth turns away again]
But there's a second receiver over here [mumble] so this is an old kind of receiver, picking up signals in random spots on the sky. We're looking at stars, but this is just pointed at random spots in the sky. Maybe somebody's using this thing [the main antenna] to look at pulsars, while this [the second receiver] is pointed at some random spot in the sky. The Berkeley guys collect data from this thing. And it's random spots in the sky, and it's moving around, and they never look at any patch for more than about one and a half seconds, so they can't use this integration trick. But they get all the data they want out of it, right? They figure, look, we don't know where ET is, and random spots are as good as any other spots. And you know, you could make that argument, nobody knows. We think it's better to look at stars, but nobody knows.
So they collect the data with that thing. And then they just have a setup over in the control room. And they collect this data and they just send it on back to hard disks in Berkeley. And then they take about 2 percent of those data and distribute them on the web for SETI@home. That's how that's done. It's much less sensitive, that data, and the real problem, actually, for them, is the followup. Because people find signals of course, just as we do. They'll find signals. And you're processing this chunk of data, these data were taken three weeks ago or three months ago, and you find something and send it back to Berkeley. And so they're running software that notes that, and just waits for that antenna perchance to be aimed back at the same patch of sky again, which it will, ultimately, once every two years or so. And it will say okay, and have that data processed, and compare those data with the ones that were processed maybe two years earlier. You know, this processed by Melvin and this processed by Molly, and see if they found the same signals at the same frequency, in which case they both get the trip to Stockholm.
Actually, even that wouldn't work, because you can work out the statistics, how often that would happen by chance, just random noise. You have to find it three times. And then it's probably...
Siduri: But people are falsifying signals, at SETI@home. There have been people actually...
Seth: Really?
Siduri: Just to get the...
[There's a break here, because we had to switch tapes in the recorder. Meanwhile, here's an old article about people tampering with SETI@home data: http://www.spaceviews.com/2000/01/23a.html]
Seth: Does this mean you're doing this?
Siduri: No, no. No, I'm not, but I was reading about security in peer-to-peer systems, and...
Cellphone: Ring! Ring!
Siduri: Oh, I'm sorry, that's me.
Seth: This could be the big one.
Cellphone: Ring!
Siduri: Be quiet. Are you going to be quiet now?
[The phone is quiet.]
Siduri: Um, and they were talking about how the fact that a person is getting no money from falsifying their end of the system does not necessarily mean that they won't do it. Like, there's all sorts of other reasons.
Seth: Money is not the only incentive?
Siduri: Exactly. And they pointed to problems that the people at SETI@home were having as an example of that.
Seth: Interesting. Yeah, I guess that's true.
Siduri: Nobody's getting paid to do this work. But people want to increase their standings, you know, so they'll just make up all kinds of stuff.
Seth: Lots of reasons other than money. I didn't know that they were actually faking the data. Because what the guys over at Berkeley normally do, is they send the same data set to at least three random downloads. So that they compare returned signals. And if somebody fakes a signal in their data, their chunk of data, it won't agree with the other two people. There's usually more than two others, but they would get the other two holders, who will agree but they won't agree with him. That kind of voting system. So I think that's the way they try and guard against this.
Siduri: So what's in Stockholm? Why would they get a trip to Stockholm?
Seth: Oh, yes, Shannon, you obviously haven't investigated that. Isn't that where they give you the Nobel Prize?
Siduri: Ohhhhkay, I see.
Seth: I think it's just the open-face fish sandwiches that everybody wants. "What's in Stockholm." Not much, I'll tell you.
Interview with Seth Shostak ?Reported 2001-12-21 19:42 by Siduri
Roswell, Dyson Spheres, and the Price of Photons
"I wouldn't even listen to this part of the tape."
Seth Shostak: "...something I probably shouldn't talk about, because the boss will get very upset about it. [mumble mumble] invasion of privacy. But, I mean, you can talk in general about the fact that the public, of course, is often unable to distinguish among things like alien visitation, abduction, the idea that there might be, you know, monuments on Mars that have been left for our edification and things like that, and what we do. There is that continuing problem, because it seems that the level of science education in the country is not very high, so they don't understand the difference between science and other approaches to trying to understand things.
And I guess from our point of view, scientists are often fairly impatient with people who don't understand science, their line of argument. That becomes obvious to me whenever I'm on a radio show where there are call-ins, because people will often call in and say, "well what do you really think about Roswell," for example. That question's almost guaranteed on a radio show. And what do I think about Roswell? I think Roswell's probably a very nice town. And I think the fact that it's claimed that aliens made a navigation error there and, y'know, somehow crashed, even though they haven't any other time, has been pretty good for the Roswell chamber of commerce. But I don't think the story has anything to do with aliens.
[Siduri]
Siduri could beat up Katie Couric
Siduri: Well, so, how does SETI?just as, you know, a first groundstarting question?how did SETI decide on radio signals rather than any other form of trying to see whether there was extraterrestrial life?
Seth: Well, that's a good question, because in fact...
[At this point The Compulsive Splicer starts menacing Seth with a camera.]
Seth: You got her, I hope, because my eyes were closed in that shot.
The Compulsive Splicer: That's fine. Yeah, I need to get all of us.
Seth: Okay. Yeah, how did SETI get started with radio. That's a good question because in fact if you think about, sort of step back from the whole question of what particular SETI experiment you're doing, you might say, "Well, how do you know whether there are aliens out there?" There are lots of ways you could conceivably know. You could look around and see if they're walking the planet. That's legitimate, although I don't think they are, but you know, you could ask that question. The second thing is you could look for astroengineering, for example. You could look for giant artifacts in space. I mean, the galaxy's been around for two or three times as long as the earth has been around, so if there are civilizations out there a lot of them?most of them?will be way ahead of us.
[Seth Shostak]
Seth has no particular affection for Neptune
Unless civilizations routinely destruct very quickly, they self-destruct because they invent technology and then they invent the H-Bomb and they blow themselves up. If that's what normally happens then maybe there aren't very old civilizations. But I'm more optimistic than that.
So a lot of civilizations could be way beyond us, so maybe they're doing stuff that you can see, that's obvious?you know, they're building something that's big. Let's see here, maybe they have giant rockets and you can see the exhaust from these rockets. Maybe the rockets have magnetic brakes and you can see the radiation from the magnetic brakes. People have thought of a lot of things. Maybe they've left, you know, giant monoliths on the moon for us to dig up, a la 2001. You know, it's not impossible. We wouldn't know, because nobody's really looked at the moon for those sorts of things.
So those are all possibilities. The trouble is most of them don't sound terribly fruitful because even though the aliens might be building big stuff, you don't quite know what to look for. I mean, how do you see it. There have been some experiments in that regime, I mean some people have done some things, they look for what are called Dyson spheres. Do you know what a Dyson sphere is?
Siduri: Um, I know of it only...
Seth: Take Freeman Dyson, you just roll him up like a marble and you have a Dyson sphere. No, Dyson spheres...
TCS: It's the Ringworld except a sphere world, right?
Seth: Yeah, exactly, exactly, which...turns out the Ringworld's a little unstable...
Siduri: I was about to say, I know of it from an old Star Trek text adventure game ["The Kobayashi Alternative"], where you went to visit a Dyson sphere world.
Seth: Yeah, exactly. You take apart some outer planet. Like Neptune?Neptune's not big in your life; you don't mind taking apart Neptune. They take it apart and rebuild it as a giant sphere, cover the inside with solar cells, for example, and that might be something that an advanced civilization might do. That kind of thing. People look for that, they look for Dyson spheres by looking for stars that have a lot of infrared. But you know, they've only looked a couple hundred stars. Not much is it?
So, there are all those approaches, but then people thought "well, maybe the best thing to do is look for signals." And the reason that got started is that a couple of guys, they were at Cornell University, a couple of physicists, just worked out really simple calculations. They said "If you take the most powerful radio transmitter on Earth, and our best receivers, how far apart can you separate these two things and still be able to pick up the radar transmissions?" And they figured, oh, well, it'd be, you know, thirty thousand miles or a thousand miles or something like that. And it turned out it was light years.
So they realized, hey, it's pretty easy to send a message that can go from here to another star. So maybe aliens are doing this. So that was 1959 and by 1960 people were already looking for the signals. Now, immediately other people said, well, maybe that isn't the only way to do it?maybe they'd be flashing lights at you or something like that. And it turns out that the physics tends to favor the radio. Mostly because, I don't know if you remember high school physics, but the amount of energy in a photon is proportional to the frequency of [Seth starts muttering equations]. Energy equals hf or [mumble mumble]. Anyhow, all that means is that light photons, a single light photon has got a lot more energy than a single radio photon. So if you want to send a bit of information from here to Alpha Centauri it's cheaper, in terms of the energy, to do that with radio than to do it with light.
So, you know, that's been the argument for many years. Now that argument isn't very solid anymore. I wouldn't even listen to this part of the tape.
"Next question."
Siduri: Well, I was gonna say, I have a list of softball questions from your biggest fan, and then I have a list of hardball questions. And one of the...
Seth: The softball questions are from my biggest fan? Is that my mom?
Siduri: No, I told you that there's a guy on the list that was a big fan of yours, and was all but asking for your autograph. And so I have a list of questions from him...
Seth: I hope he's not a Czech. [I think that's what he said. He was muttering again.]
Siduri: Hum?
Mark Territory: From Scotland?
Siduri: Uh, yes.
Seth: Scotland?
TCS: Paul from Scotland?
Siduri: Yes.
Seth: Paul?
Siduri: Um, he's just seen you I think, on like, radio shows.
Seth: Seen me on radio shows.
Siduri: Or, heard you on radio shows.
TCS: Heard you on TV. [Everyone's talking at once. I'm not sure this was what Splicer said.]
Mark: Might be a stalker, I don't know.
Siduri: But he's in Scotland, so I don't think you have to worry about him. But anyway, so one of the hardball questions was: "Our own civilization has only been using radio to transmit messages for less than a hundred years. Now these messages are increasingly being delivered in a digital, often encrypted form that is practically indistinguishable from white noise. What sense does it make to search the radio spectrum for such old-fashioned messages that we ourselves have only bothered using during this brief window?"
Seth: Good question, Paul.
Siduri: No, that wasn't Paul. That was Zach.
Seth: Good question, Zach. Next question.
No, no, no, he was absolutely right. I mean, if you look at the kind of signals that we're currently using, sort of spread-spectrum signals and things like that, they're very complicated, and they're completely unlike the kind of things we look for in SETI. The kind of things we look for in SETI are signals that are just what are called narrow-band signals, that are on one spot on the radio dial. So they take all the energy of the transmitter and pump it all into one small frequency range. Okay? You with me?
Siduri: Yeah.
Seth: All right. The advantage of that is that it makes it really easy to find the signal because all the energy is in a small band so it really stands out as a big spike of energy. Whereas if you spread it out over five megahertz, like a TV signal, then the energy's spread all over the band and it's very hard to find. But on the other hand, the actual signals that we use are spread out, more and more. And ET will be at least as advanced as we are, so you might say, "Well, why would they make those narrow-band signals?"
And the answer is, probably: most of the time, they don't. For their own internal communications they probably wouldn't do that. But if you have a beacon, which you want to hear at great distance?if for some reason they want to get in touch, or they're sending the galactic weather report, whatever, GPSs?there's lots of things that would have narrow-band components in the signal. So that's what we look for. But Zach has a point.
Siduri: So the assumption is that they would have to be kind of trying to get in touch.
Seth: They might have to be trying. Or, I'm not sure I would even go that far. If you asked Marconi a hundred years ago, what would he think the radio signals would be like in the year 2001, or whaddya think people will be using this technology for in the year 2001, he wouldn't have had a very good idea. He probably wouldn't have gotten it right?not much of it, anyway. So for us to say what kind of signals ET uses, a hundred thousand years ahead of us, what kind of signals he's producing?you could guess if you want. Probably not a very good guess.
I mean, one thing you always need is high-powered radar to look for incoming comets. Long period comets. Cause they can come in, and as you know, ruin your whole day. Land in Yucatan. But I mean, he has a point. It's just that we're looking for the signals that are easy to find.
[Mark Territory]
Mark follows TRUTH like a shark follows BLOOD
Mark: Are we also looking for the signals that might be accidentally broadcast?
Seth: Yeah, well, that's the question, and that's the question that Zach is really asking. And Shannon jumped to the conclusion, as she is wont to do, that we can only pick up deliberately broadcast signals. But you don't know what ET's using radio for, so...
Siduri [jumping to a conclusion]:...We could happen on something.
Seth: Yeah, we could trip on, as I say, a radar that they're using to warn about incoming Klingons, if you don't like radar warning about incoming comets. And in that case, then...
Mark: We'll get to those questions later.
Seth: And then you can say, "Well, it wasn't deliberate, but we got it anyhow," see. So in a sense SETI doesn't care. Yeah, what do we care.
How the Hell That All Works
"And if you don't hear ET there? Well, tough toe-corns."
Mark: Now, I imagine there must be many, many false alarms. Things that are picked up and determined to be background noise, anomalies, perhaps galaxies emitting natural things that while they have patterns, they're not signs of intelligent life. How do you determine whether a pattern is background noise or a signal?
[Seth Shostak]
Seth indicates where the ay-leens come from
Seth: Yeah, well, this is a question we get asked a lot?"Do you have a cryptologist or a cryptographer sort of looking at these things to say, well, this looks natural, that looks artificial?" In a way we do, although we really don't. We don't have any cryptographer. We can barely afford to have someone just clean up the rooms. The way it's done is, the nature of the signal itself is the decryption. If it's a narrow-band signal, that's something that's really easy to build a transmitter to make, but that's extremely difficult for nature to make. Nature doesn't make narrow-band signals.
I mean, listen to quasar with a radio telescope and you hear "PSHHHHH." It almost doesn't matter where you turn your knob, you'll hear that blank noise 'cause it's all across the band. Even if you listen to a pulsar, pulsars go on and on, maybe a thousand times a second, faster in some cases. But what you hear is "PRRRRR" or "PSH-PSH-PSH-PSH-PSH." It's still white noise. It doesn't matter where you're tuning your radio. You'll hear the pulsar, you see. Tune across a wide, wide range of frequencies and you still hear "PSH-PSH-PSH." So that's clearly nature because nature doesn't care about wasting a lot of energy. No person who was designing a transmitter would build one that sent ten pulses a second all over the band. It's a total waste of energy; it's bad engineering.
So that's how you do it, you say, "Hey look, if they put all the energy into a small region of the dial, that's something nature never does but transmitters do all the time." So that's how you tell.
Mark: Now, have we scanned the entire spectrum?
Seth: No, not by any means. We have only looked at a tiny fraction of the radio spectrum. Our experiment, Project Phoenix, which is run by the Institute?[pointing to a photograph on the wall] that antenna, the one in the middle?looks at more of the spectrum than any other experiment ever has. It's looking over from 1,000 to 3,000 megahertz. Each channel is about 1 Hz wide so that's like 2 billion channels for each star that we look at. That's still not the whole spectrum.
Mark: This is actually a question that came from one of our contributors. I don't know if it was Paul or Zach. They were under the impression that the signals are scanned for 300 seconds, approximately?
Seth: Yeah, that's about right.
Mark: How do you determine which bands to target first?
Seth: Oh, well, we just start at the bottom of the band and work up. How are you gonna know. If you start at the bottom of the band you may miss ET's transmission at the top of the band, yeah, but maybe if you start at the top of the band you'll miss his transmission at the bottom of the band. You don't have any information about that so you just?it's a matter of being methodical. We always do it the same way. Start at the bottom of the band and work up. It takes, you know, about ten to twelve hours to go through all those frequencies for any given star.
Mark: Yeah, but how much information is captured in that five minute window?
Seth: Well, in a five minute window you're listening to 28 million channels. So you're getting information about 28 million, actually, it's 56 million channels. It's 28 million frequency channels, but the receiver has?there are two polarizations that you're actually sensing, so there are actually two receivers in one at the focus, so it's actually 56 million channels. So during that five minutes you're looking for signals that are within those 28 million frequencies. And if you don't hear ET there? Well, tough toe-corns, move up and do 300 seconds on the next batch of frequencies. No ET? Go up the dial a little bit and do more, and that's the way it's done. And actually, observing one star isn't done at once, it's done in pieces, over the course of a couple days.
Siduri: I believe Paul's exact question was, "Ask how the hell that all works."
Seth: How the hell that all works. Well, what didn't I answer?
Mark: Perhaps you could start by telling us, once the data is collected by the telescope, where does it go? The project has been going on longer than hard drives have been in common use to store this data.
Seth: Mm-hmm.
Mark: Does it get printed out onto paper reels?
Seth: In the old days it was printed out on paper, yeah, it was. Not anymore. Those were the good old days. You could come in and there was only one channel, or ten channels, or some small number of channels, a hundred channels. So it was possible to put all the data out on a, usually a line printer. In the very earliest experiments it was just a strip-chart report. You know, one pen on a piece of paper. Maybe two, if you had two pole positions. When Frank did the first experiment in 1960, that's the way it was done. He just had a little motor that essentially turned the knob on the receiver and turned it up and down the dial, very slowly, you see, so the frequency was changing. And you could just look at the output. And he had a loudspeaker connected to it. It was all very simple. And then ten years later you could look through a hundred channels at once, so then you needed a line printer.
That was what was being used in 1977 at Ohio State, when some guy came in in the morning looking through the stack of computer printout, and saw one big signal and said "wow!" Wrote WOW next to it. The Wow Signal.
Mark: Can you talk a little bit more about that?
Siduri: Yeah, whatever happened to that?
Seth: Yeah, the wow signal. Well, it's pretty wow-y. But it doesn't seem to have been ET. Lots of people have gone back and they even, they immediately had a following beam on the sky that swept through that same patch of the heavens, just shortly after they got that signal, and didn't see it. And people have gone back there looking, you know, with more sensitivity, more frequencies, and nobody's ever found it again. So it's not good enough. It's like seeing a ghost in your basement once. It's not enough to believe in ghosts. If you see them every time you look, now that's okay, you might believe then. So it was undoubtedly some sort of interference.
Siduri: Is that the closest you've ever come to finding...
Seth: Well, how do you know? That's like pregnancy, I mean, are you close? It's not a matter of close, it's yes, it's a one-bit experiment. It's not that you're close. There have been lots and lots of false alarms. Particularly in the early days, because in the early days you would usually report the data. As you said, it was before hard disks. But what would happen is that you would go the telescope and you had a hundred channels, and normally you would just write everything to computer tape. Back with these big tapes, and you would put them on computers wherever you were, and play 'em back, and then look at all the data.
And you'd always find signals. You've got these huge antennas, you know, with very sensitive receivers, and hundreds of channels, thousands of channels, and now millions of channels, so of course you found signals. But then what did you do? What do you do with them? You could call up the local papers and say, "By the way, I found all these signals," and that would work the first time. But, well, how do you know it's ET? And you say, "well, I don't know." Then the next time you went back to Tucson you'd try to look at those parts of the sky again. And that's very tedious.
But now, what we do, is we check out all the signals right away, in real time. All the data's processed real time. So you don't leave the telescope with a stack of mystery signals. You know each one of them because you tracked it down. So in the early days there were lots and lots of these sorts of false alarms. Not anymore.
Mark: Does that mean that the sensitivity to signals may be less now than it was before?
Seth: No, the sensitivity's clearly better now. The sensitivity's better but the processing's better. That's just because, you know, digital electronics is better than it was. So now you can conceivably process everything in real time. That's the way it's done. When you're sitting down there in Puerto Rico, you're sitting at the control room, and the signals are coming in about?you get hundreds of signals every night. Hundreds. And each one of them is checked out. So far each one of them has been us.
Well it is rocket science, but it's not hard rocket science."
[Siduri]
Siduri trusts no one
Siduri: But now, I thought that was what SETI@home was doing.
Seth: Well, that's a different project. That's a Berkeley project. We process all our data, as I say, real time. And any signals that look like they're good are verified by a second telescope at Jodrell Bank, in England, just south of Manchester. We have a slow-speed line that sends the information about a handful of signals, whatever you have in those 300 seconds, sends that information to Jodrell Bank. And then they're looking at the same star. So here we are in Puerto Rico, and there they are in Jodrell Bank. And we're both pointing at the same star, so if we find signals here, then these guys spend the next 300 seconds checking those out. So they're always 300 seconds behind the Arecibo telescope.
Siduri: That's clever.
Seth: Yeah, and obviously, if it's really ET, you know you should be able to find it in both places. But beyond that, you're on the rotating earth, and if you do a little geometry you realize that, well, the motion of the earth means that these two telescopes are moving?with respect to whatever star it is you're looking at?at a slightly different rate, so there's a slightly different Doppler shift, so the frequency ought to be different here than there. A small amount, but it's easily measured, see, so there's a little microcomputer that does that simple high school geometry, and looks for that change in the Doppler shift. And if it doesn't find it, then it knows this is not ET: this is a telecommunications satellite. So that's another trick.
So they all get checked out. Now, SETI@home, that's data that's taken by the Berkeley crowd, on the same telescope but in a different way. And their data is of a nature that, you know, you can look at it two months later and still be interested. With ours, ours is so sensitive that if you found anything, you would want to check it out right away.
Mark: And how often does that happen? Do you get calls in the middle of the night, saying "check this out right away"?
Seth: Well, I'm usually sitting there. I usually have the 6 to midnight shift; Jill Tarter takes the midnight to 6 AM shift; Peter Backus comes in and spells one of us. You're actually there. And if it finds a signal, I mean, it doesn't?you don't get these giant klaxon sounds and red flashing lights. MM-NEE! MM-NEE! I mean, that would be great, that's what it is on Star Trek, but what actually happens is the workstation goes "beep." You barely notice it.
But then it says, you know, "I found these six candidate signals," it's a real signal. And what it does is, it sends them to Jodrell Bank, right. And if they come back from Jodrell Bank?almost always, they come back "sorry, Charlie, this is not it"?but every now and again something gets through the filter. So Jodrell Bank says, "Looks good to me." And meanwhile it's looking in a database of known interferers to make sure it isn't in there.
If all these systems are "go, this could be the big one," you still don't call up the airlines and get a ticket to Stockholm. Because what happens next is it, you know, "beep beep," it comes again. And you're still not paying much attention. But now what it's done, because it's found a signal that both telescopes think might be real, it breaks the observing. It stops going up the dial and it now moves the Arecibo telescope away from the star. Just a little bit. Maybe the diameter of the moon or something like that. Just that far away. And the signal ought to go away now. If it's really ET, if it's really coming from the star, the signal oughtta go away. Now, if the signal's coming from some telecommunications satellite that's wheeling overhead, that signal's bouncing all around, I mean it's so strong, bouncing around the telescope structure, it doesn't really matter where you point the antenna. You'll pick up that signal. So, if you point away from the star and you still get the signal, you know right away it's not ET.
But if it goes away, it might be ET. Or maybe the telecommunications satellite just went over the horizon at the same time. And that can happen too. So if it goes away, then you keep looking, and you move the antenna back on the star and see if the signal comes back.
Siduri: Does your heart start speeding up at about that point?
Seth: At about that time, if it goes off, and it goes away, then you pay attention. Because it's sort of fun. And you always set the sensitivity so this happens once every couple nights. And if it doesn't find it there and then it comes back and it does find it again, then, yeah, then you become more interested. And if it goes off and doesn't find it, then you're standing up. That doesn't happen very often. It's happened to me once or twice. That's when you get excited.
And at some point, you know, it'll do this half a dozen times, and then it sort of throws up its little computer hands and says, "I don't know what this is anymore. This is something you know how to decide. I don't know what to do next." I don't know, I think only once has it ever gotten to the point where the computer didn't know what to do next.
Siduri: While you were there, or...?
Seth: Well, I was downstairs, and we were observing simultaneously?No, we had a remote setup downstairs. I wasn't actually at the telescope. This was '97, I was at Greenbank, but the second telescope that we were using those days wasn't working that day, and that was how we got fooled.
Siduri: Ohhh.
Seth: But we got fooled for something like 16 hours. That was pretty interesting. It was very interesting to see how people reacted when it looked like this was the real thing.
Siduri: How did people react?
Seth: Everybody was simultaneously excited and nervous. That's true. Nobody went home, nobody went to bed. People just hung out. The engineers were all hanging around the computers downstairs. And I half expected that we were going to see the government show up. Everybody expects that the government would move in if we ever got a signal. But the government had no interest in moving in. Much to my disappointment. Even the local, the Mountain View government didn't want to move in. Nobody wanted to move in.
[We laugh. But, transcribing this, it occurs to me that a real conspiracy theorist could take this as proof that the government already knows about aliens! Because why wouldn't they react to an extraterrestrial signal, unless they had some way of knowing that it was a false alarm? And how could they know that, unless they already knew where the real aliens were? Hmm?]
Seth: I sort of hoped that the pizza guy would move in. We were getting hungry. But what did happen is that the media started calling up.
Siduri: How'd they know?
Seth: Somebody just called them. I mean, there's no secrecy, so, you know, they called up the New York Times. And they called me: "What about that signal?" I said, "Well, we're following one, but, you know..."
Siduri: So you would really know right away.
Seth: Oh, you would know right away. Yeah. In fact, I really do believe you would not only know right away; you would know before we had fully checked out the signal. Because how long is it going to take us before we believe it? I mean, surely within an hour or so you'd be beginning to get the idea that this might be it. But it still could be a software bug, it could be?you know, there are all sorts of things that can go wrong. It's an extremely complicated system. It involves two telescopes, it's a one-off device so needless to say it isn't fully debugged, and all that. So you'd say, "okay, this is looking interesting, but I'm not sure I'm going to tell the world I found ET yet. I'm going to call up somebody at another antenna, another radio observatory, and say, 'You check this out, with your equipment, not ours. Because you've got a completely different system, and maybe yours isn't buggy or whatever, if that's what it is.'"
And they would say, "Okay, well, we'll do that, but we can't get to it until tonight, because, you know, the star isn't up yet, or we have to change the receiver," whatever. So they'll spend some time doing that, it'll maybe take a day or two. And so surely, four days, five days can easily go by before enough have seen it to say "Okay, I'm willing to stake my reputation on it. This is for real." But long before that happens you'll be reading about it at Albertson's in the check-out line. That media won't wait; they'll run with the story before you've confirmed it. Everybody will, they'll be going "oh, the sky is falling, interesting signal!" So that's the way it will happen.
Siduri: So you actually do observation work on a regular basis.
Seth: Yeah, I go down there. We observe at Arecibo. These are some pictures I took; I didn't take that one, but this is what we were using when we found that interesting signal. In fact you can see the box over there, that trailer, that's Project Phoenix. That's in West Virginia. The other one's in Australia. So we get to use this for a couple weeks in the spring and a couple weeks in the fall.
Siduri: How many observers are there?
Seth: Well, we're doing SETI so we observe at night, because the sun would mess up these narrow-band signals, so for us it's better to observe at night. So we observe from 6 PM to 6 AM. We just break that into two shifts, from 6 to midnight and midnight to 6. So you only need two astronomers, actually, but usually there are three of us there?Jill Tarter, who was sort of the prototype for the Jodie Foster character; Peter Backus, who heads up the observatory operation; and myself. The three of us. But there are also a bunch of engineers. The engineers are much more valuable than the astronomers. The astronomers are pretty stupid, and the engineers are pretty savvy; they're much smarter than we are.
Mark: I have to ask, it seems like a false positive signal would be about the best April Fool's joke ever. Has it happened yet?
Seth: Oh, you mean where somebody would try and sort of hoax a signal? Yeah, well, we've thought about it, and maybe they have too.
Siduri: [laughing] Thought about it.
Seth: Well, we wouldn't do it, because it's very important that people have faith in our?that this is a good experiment, that's competently run, that's important to us, because we're running with their money, after all. So we have to do the best job we can, so obviously we're not going to make a hoax. But somebody else might. Maybe a couple undergrads would find it interesting to do that.
But it's actually quite hard because?you know, getting a signal into the Arecibo telescope probably isn't all that hard; you have to just walk up there with a transmitter and turn it on. You can do that, I can picture that. Of course it has to be in the right frequency bandwidth at, by the way, I might say, the right time, because we're only looking at a certain small part of the band at any given time, so you're gonna have to know all that, but it's not? well it is rocket science, but it's not hard rocket science. Yeah, they could do that, they could do that.
But the point is that they then also have to fool the guys in England. So they gotta?now it's becoming bit more involved, right, because now they have to have two telescopes that believe this signal. They've got to get the right Doppler shift, so they'd better know their geometry. And then they've got to be savvy enough to, when we do this very simple test where we move the telescope back and forth, to turn the transmitters on and off. So they essentially have to be, it really has to be an inside job, I would say, because they need to know what we're doing when. And I don't see it happening as an inside job. It's just not going to happen. But, you know, I won't say it's impossible. I think it's very, very hard. Very hard, but certainly not impossible. That's why you would check it out for a few days.
"I think that if you had real physical contact?I can't imagine that would be good."
Mark: There was another question Zach had.
Siduri: Zach has great questions.
Mark: Essentially the gist of his question was: by sending out radio signals into space, we may be able to alert other civilizations, other intelligences, that we are here.
Seth: Mm-hmm.
Mark: Is that a good idea?
Seth: Well, depends on how you regard the aliens.
Siduri: [quoting Zach] "Do you believe that the aliens would be friendly, and if so, why?"
Do you believe that the aliens would be friendly, and if so, why?
Seth: Yeah. Well, who knows, I mean I'm not a specialist on alien psychology, but then again who is? Nobody is. Nobody knows what the aliens would be like. About all you can say is that on Earth, aggression pays, a certain amount of aggression. And if you sort of look at the history of, you know, being found by more advanced civilizations, it usually doesn't work out in your favor. I mean, the Indians kind of welcomed the Europeans at first, but then they all got smallpox and things like that, I mean it wasn't a good deal. They got wiped out. And it wasn't just the disease, they got wiped out, you know, culturally.
The South Sea Islanders was always of interest to me. James, Captain James Cook's explorations. And he was under orders from the admiralty not to hurt anybody, and he by and large didn't. He almost never hurt anybody, and only when they did something pretty atrocious. He was only there to collect information. Nonetheless, when he lands in Tahiti or Fiji or whatever, these guys are sitting around, they're happy worshiping red feathers and rocks and things like that. And these guys sail into their bay, and they've got these big ships, and they've got cannons, they've got metal, they've got the wheel for goodness sakes?they've got all this stuff. And somehow after you've seen that, worshiping these red feathers just doesn't seem, well, that interesting anymore. These guys are clearly way ahead of you technologically, and they must be ahead of you spiritually as well, so whatever religion they've got is clearly better than what we've got.
You know, that kind of thing so rapidly destroys your culture. Now that's a situation where these guys weren't there to hurt anybody. So I think that if you had real physical contact?I can't imagine that would be good. And even in some sense, getting information might have some negative effects, if you understood it. Because if suddenly they're saying, "hey, here's all this science, here's all this physics, so guys who are doing all these research projects at Stanford Linear Accelerator, you can keep doing that if you want, but maybe you want to read this. Oh, the cure for death, yeah, that's over here too in this section, you might want to read that." That would be somewhat discouraging for a lot of people. But I don't think it will come to that. I don't worry about any of that.
Siduri: Why not?
Seth: Well to begin with, we are broadcasting out into space. You could say, hey, that's a dangerous thing to do. But SETI isn't doing that, I mean, that's not us. That's ABC and NBC, and if you're really worried about it, you should petition the networks to shut off their transmitters, because they may be only ensuring the destruction of civilization as they know it. I mean, you could do that; maybe you should. But I wouldn't worry even about that. To begin with, most of those signals are very diffuse. TV is on all the time, of course, and they are high-powered transmitters, but it turns out they don't deliberately broadcast in the direction of space very much. Advertisers don't see a whole lot of benefit.
So they don't do it. The military radar does broadcast out into space, that's much more detectable. But even so, we've been on the air for 50 years. The galaxy's been here for 10 billion years. Fifty years is a very small fraction of that. And in another 10 or 20 years we won't be broadcasting into space very much, because everything will be?you'll have a fiberoptic line coming into your house, you'll get your TV that way. So this is a very temporary problem.
Mark: But if we assume that an alien civilization is more advanced than us, and has done away with the need for this wasteful broadcasting using radio waves...
Seth: Then what are we listening for?
Mark:...and has more efficient means of communications, might they also think that it's a bad idea to broadcast out, because there might be someone bigger and tougher than them? Might there be thousands of civilizations that are remaining silent for that reason?
Seth: Yeah, right, exactly, everybody's intimidated. Yeah, could be. That's been proposed as an explanation for why we haven't heard anything. They said, "Yeah, well the reason you haven't heard any aliens is because it's not a good idea to shout in the jungle." Right? Cause there's things out there that are bigger and have longer teeth than you do. It's not a good idea. There may be some truth in that, but again, this is sociology, so what do you know. But I do find it difficult to believe that all civilizations are that way.
You might say, "Okay, look. Broadcasting from our planet is not a good idea. We don't know what's out there. But putting a radio beacon over there, right, so that we can navigate over these short distances that we want to cover in our galaxy, that's not so horrible. I mean, they may find a beacon, but the beacon isn't where we are, the beacon's over there." Or you just send robotic vehicles out into space, and they don't transmit until they get very far away, or something like that. There are lots of ways to beat this rap.
And it may be that you feel you are the meanest dog on the block, you know, you just don't worry about this. You're the Galactic Federation, so you've got a license to do what you want. It's like the British navy. They're not afraid to take to the high seas. I don't know. It's all very interesting, and obviously very speculative. And you could say, you could talk yourself out of this, and say, "Nobody's ever gonna broadcast, it's entirely too dangerous." So then what do you do. Just don't listen? You don't get anywhere that way. At least if you listen, you have the chance of proving this thesis wrong in some way, and you have very interesting information if you find something.
So it's sort of like sitting around with Chris Columbus in 1492 and saying, "Forget the wooden boats, Chris. They probably won't work, and you won't find anything interesting anyhow." You could probably talk him out of it. But, you know, it probably was worth trying the experiment. But obviously, I work for the SETI Institute. We think it's worth trying the experiment.
"So that's kind of neat."
[Splicer]
Splicer looks into the Pattern, as
the Pattern looks back at him
TCS: Do you look at things other than the simple narrow-band signals? Do you look at the patterns that are created here on Earth, to see perhaps what you should be looking for?
Seth: Well, no, not so much, because keep in mind that in order?if there are radio signals washing over this room right now, as we expect that they are, then they're going to be weak. Because if they were really, really strong, probably we would have found them by now. There have been some surveys in the entire sky. And so if there were persistent, very powerful signals somewhere in the sky, those would have been found. So the expected ET signal is not going to be, you know, enough to cook birds at this distance or anything like that. They're going to be weak.
And in order to find weak signals one thing you can do is, as it were, make a time exposure. Just the way, with a camera, if you want to take pictures at night, you leave the shutter open for a long period of time and let the light build up. You can do that, and you can see very faint things that way. Astronomers do that all the time. But if for example you were making a photo of a pulsar, with a telescope that way, and you exposed the film for 20 minutes, then you wouldn't know that pulsar was flashing, would you? It would just be a bright spot on the film.
Well, we do exactly the same thing in the radio. We, as it were, integrate the signal over 300 seconds in order to build up the sensitivity. But that means if it's changing a hundred thousand times a second, or millions of times a second the way a TV signal does?all that's gone. It's all lost. So that's why finding the message is much harder than finding the signals; finding the signals you can integrate. What we do do is, we look at?we break up the data into one-second chunks, and we see if there are any pulses in there. Slow pulses. Beep. Beep. Things that are longer than a second in frequency. Then we would find those. We do look for those kinds of pulses. But nothing more complicated than that, because of the sensitivity.
Siduri: I think Steve was asking, though, if we were looking at what we're sending out there, just accidentally?
TCS: That's what I asked, although I think that Seth in his answer addressed that that was not...
Seth: I should have said...
TCS:...that it wouldn't be very fruitful to figure out what we're sending out if we're not going to be able to hear it.
Seth: Right. What you're saying is that what we should be looking for is the kind of stuff that we send out?
TCS: Right, and you said that we wouldn't be able to hear the kind of things that we send out.
Seth: Yeah, what you could hear from Earth are powerful military radars?not very interesting to listen to, but powerful?or TV signals. You know, one-third of the power in the TV signal is from the carrier, which is this very narrow-band component of the TV signal. I don't know if you know this, but a TV signal is spread out over four or five megahertz?a big chunk of the dial. But there's a very sharp carrier component, which your TV set needs to tune in. So one-third of the power is going in there. And that's 10,000 times easier to find than the picture itself. So that's what you would hear from Earth, is carrier signals. Really big antennas could see I Love Lucy. You'd know that the TV transmitter is on, you just wouldn't know what show it is. If you want to know the show you'd need lots of antennas.
Mark: Is SETI looking at different kinds of modulation other than just amplitude?
Seth: Well, as I say, we don't look for really modulation at all, we just look for energy within a given band. The way it's changing...
Mark: Perhaps polarization changes, or...
Seth: Yeah, you could look for all that, those are ways to encode information on the message. But unless it's very, very slow?really slow?then we won't see it, because we just average everything. As I say, it's like taking time exposures. Take a picture of the city and you'll see that the stoplights have red, green, and yellow all lit up on the film. All the real information about how that's cycling is gone.
Siduri: Now, isn't there an optical SETI program starting up?
Seth: Yeah. There is. In fact, that's the Berkeley one; picture's over here. But there's one the Institute is involved with, and that's at Lick Observatory, down near San Jose. You ever been to San Jose?
Siduri: Uh-huh.
Mark: Nice drive up there. I wondered what those...
Seth: Mostly, they?actually, that's where a lot of these extrasolar planets have been found.
Siduri: Really?
Seth: Yeah. Geoff Marcy, who found probably more than anybody, works at San Francisco State, and Berkeley. But that's a telescope that he's been using. Now he's using the Keck telescope in Hawaii. But they still use this thing; they use it for a lot of stuff. Anyway, there's a telescope out there; I have a picture. There's a telescope up there with a one-meter mirror, and this young lady, Shelley Wright?she was an undergraduate, 23 years old I guess, or 22?she built a box to go in the back of this thing to look for flashing laser pulses. And so every night they use that telescope?not every night: those nights that it's available, which is about half the nights?they point it at nearby stars.
What they're looking for is flashing lights. And the reason this makes sense is because?I mean, you might think "Enh, that doesn't make sense, because the star itself is putting out a lot of light and that'll swamp any laser on a planet orbiting the star; you can't even see the planets, how could you possibly see somebody's laser?" Well, it turns out that if you take the most powerful lasers that we could make, the ones they have at Lawrence Livermore and places like that, that if you aim that laser into a mirror that's the size of this table or something, and then aim it at a nearby star, and put all the power from that laser into a billionth of a second flash, you see, concentrating the energy in time now, then for a billionth of a second that laser will outshine the star.
Siduri: Oh wow.
Seth: Yeah. So, what she does is, she just looks for a billionth of a second and looks for a bunch of photons coming in. It wasn't originally her idea, but that's the experiment we're involved in. And that's kind of neat, because nobody's really done that much before, so you could maybe find something. Maybe some alien civilization nearby has a big laser, and they've just got a little mirror assembly for the output of the laser, and it directs the light onto a big mirror [mutter mutter]. But, you know, they just ping each star that's near them for five seconds a day or ten seconds a day. They don't know which ones might have civilizations, but they just do this, automatically. And then all we have to do is get a lot of people looking at a lot of stars and we'll see some that are pinging our way. So that's kind of neat.
Siduri: How long has this been going on for?
Seth: It's been going on for about six months. I mean the idea of looking for flashing lights in the sky is not new, but actually doing it is new.
I mostly use my FreeBSD box for programming. I don't even use X that much. I am curious as too how far I would have to clock down a newer processor so as to not need a fan at all. Not many ideas for the PSU other than moving it though.
As FreeBSD has showen (working closely with Apple) being BSD allows for co-operation with industry, which can be advantagous, however If a company choses to close the source completely then they can simply be ignored. Conversly if they wish to implement a partially open operating system (as apple have done releasing the code under the terms of thier own licence) then the BSD is flexible enough to allow them to do this, whilst still contributing code back to the community under the terms of the BSD.
Re:Mac OS X sucks?? I'm confused
on
xMach GPL Free
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· Score: 1
A small clarification: OS X is actually Mach with a BSD unix layer on top. I to however wish to see more varients as I feel that they generaly increase quality, dispite the traditional 'less unix acceptance due to too many venders' argument, as this is normally only taken by comercial vendors.
As always people being comparing KDE and GNOME on appearance. THEY ARE BOTH CUSTOMIZEABLE. Stop whinning, this post was about the new features of QT 3, not about KDE vs GNOME, which is an impossible argument to wage as both have strengths and weeknesses, but please in future please don't claim one is better than the other on the strength of their default look and feel.
things like this are really positive for all our high security OS's out there. Hacking/Cracking is an extremely positive activity when put to actally helping me secure my box.
Slashdot Mirror
This is the part that I figured probably has the most relevance to the slashdot crowd:
SETI@home
"I think it's just the open-face fish sandwiches that everybody wants."
Siduri: So what's the relationship between the SETI Institute and SETI@home?
Seth: Cordial. Well, there aren't many SETI experiments in the world. To begin they figure SETI's all one giant organization, which it's not. SETI's just an acronym. There are a half a dozen SETI experiments going on. But in terms of radio SETI, the big ones are right here in the Bay Area. What the Berkeley guys do, they're just two guys.
Siduri: So there's no formal relationship.
[Seth ]
This is Seth's telescope, but sometimes
he lets other people drive it
Seth: Well, we support them, we give them a bit of money, because we know these guys. But it's a different experiment. What they do?I'll tell you what they do, because it's pretty interesting. If you look up you can see there, [pointing to a photograph] you see the way this thing works, which is that there's a big reflector: the radio waves come in, they bounce off, and they go into here, this buckyball [there's a bit I can't make out here; Seth is facing away from the tape recorder] boink boink, and then into the receiver. So that's what we're using. By moving this thing around on these tracks, we can point to anywhere within 20 degrees of the receiver, and then you just wait for the Earth to rotate. You get a lot of the sky with this thing. And then this telescope is pointed straight up and you can actually see... [voice trails off as Seth turns away again]
But there's a second receiver over here [mumble] so this is an old kind of receiver, picking up signals in random spots on the sky. We're looking at stars, but this is just pointed at random spots in the sky. Maybe somebody's using this thing [the main antenna] to look at pulsars, while this [the second receiver] is pointed at some random spot in the sky. The Berkeley guys collect data from this thing. And it's random spots in the sky, and it's moving around, and they never look at any patch for more than about one and a half seconds, so they can't use this integration trick. But they get all the data they want out of it, right? They figure, look, we don't know where ET is, and random spots are as good as any other spots. And you know, you could make that argument, nobody knows. We think it's better to look at stars, but nobody knows.
So they collect the data with that thing. And then they just have a setup over in the control room. And they collect this data and they just send it on back to hard disks in Berkeley. And then they take about 2 percent of those data and distribute them on the web for SETI@home. That's how that's done. It's much less sensitive, that data, and the real problem, actually, for them, is the followup. Because people find signals of course, just as we do. They'll find signals. And you're processing this chunk of data, these data were taken three weeks ago or three months ago, and you find something and send it back to Berkeley. And so they're running software that notes that, and just waits for that antenna perchance to be aimed back at the same patch of sky again, which it will, ultimately, once every two years or so. And it will say okay, and have that data processed, and compare those data with the ones that were processed maybe two years earlier. You know, this processed by Melvin and this processed by Molly, and see if they found the same signals at the same frequency, in which case they both get the trip to Stockholm.
Actually, even that wouldn't work, because you can work out the statistics, how often that would happen by chance, just random noise. You have to find it three times. And then it's probably...
Siduri: But people are falsifying signals, at SETI@home. There have been people actually...
Seth: Really?
Siduri: Just to get the...
[There's a break here, because we had to switch tapes in the recorder. Meanwhile, here's an old article about people tampering with SETI@home data: http://www.spaceviews.com/2000/01/23a.html]
Seth: Does this mean you're doing this?
Siduri: No, no. No, I'm not, but I was reading about security in peer-to-peer systems, and...
Cellphone: Ring! Ring!
Siduri: Oh, I'm sorry, that's me.
Seth: This could be the big one.
Cellphone: Ring!
Siduri: Be quiet. Are you going to be quiet now?
[The phone is quiet.]
Siduri: Um, and they were talking about how the fact that a person is getting no money from falsifying their end of the system does not necessarily mean that they won't do it. Like, there's all sorts of other reasons.
Seth: Money is not the only incentive?
Siduri: Exactly. And they pointed to problems that the people at SETI@home were having as an example of that.
Seth: Interesting. Yeah, I guess that's true.
Siduri: Nobody's getting paid to do this work. But people want to increase their standings, you know, so they'll just make up all kinds of stuff.
Seth: Lots of reasons other than money. I didn't know that they were actually faking the data. Because what the guys over at Berkeley normally do, is they send the same data set to at least three random downloads. So that they compare returned signals. And if somebody fakes a signal in their data, their chunk of data, it won't agree with the other two people. There's usually more than two others, but they would get the other two holders, who will agree but they won't agree with him. That kind of voting system. So I think that's the way they try and guard against this.
Siduri: So what's in Stockholm? Why would they get a trip to Stockholm?
Seth: Oh, yes, Shannon, you obviously haven't investigated that. Isn't that where they give you the Nobel Prize?
Siduri: Ohhhhkay, I see.
Seth: I think it's just the open-face fish sandwiches that everybody wants. "What's in Stockholm." Not much, I'll tell you.
Interview with Seth Shostak ?Reported 2001-12-21 19:42 by Siduri
...We could happen on something.
...and has more efficient means of communications, might they also think that it's a bad idea to broadcast out, because there might be someone bigger and tougher than them? Might there be thousands of civilizations that are remaining silent for that reason?
...that it wouldn't be very fruitful to figure out what we're sending out if we're not going to be able to hear it.
Roswell, Dyson Spheres, and the Price of Photons
"I wouldn't even listen to this part of the tape."
Seth Shostak: "...something I probably shouldn't talk about, because the boss will get very upset about it. [mumble mumble] invasion of privacy. But, I mean, you can talk in general about the fact that the public, of course, is often unable to distinguish among things like alien visitation, abduction, the idea that there might be, you know, monuments on Mars that have been left for our edification and things like that, and what we do. There is that continuing problem, because it seems that the level of science education in the country is not very high, so they don't understand the difference between science and other approaches to trying to understand things.
And I guess from our point of view, scientists are often fairly impatient with people who don't understand science, their line of argument. That becomes obvious to me whenever I'm on a radio show where there are call-ins, because people will often call in and say, "well what do you really think about Roswell," for example. That question's almost guaranteed on a radio show. And what do I think about Roswell? I think Roswell's probably a very nice town. And I think the fact that it's claimed that aliens made a navigation error there and, y'know, somehow crashed, even though they haven't any other time, has been pretty good for the Roswell chamber of commerce. But I don't think the story has anything to do with aliens.
[Siduri]
Siduri could beat up Katie Couric
Siduri: Well, so, how does SETI?just as, you know, a first groundstarting question?how did SETI decide on radio signals rather than any other form of trying to see whether there was extraterrestrial life?
Seth: Well, that's a good question, because in fact...
[At this point The Compulsive Splicer starts menacing Seth with a camera.]
Seth: You got her, I hope, because my eyes were closed in that shot.
The Compulsive Splicer: That's fine. Yeah, I need to get all of us.
Seth: Okay. Yeah, how did SETI get started with radio. That's a good question because in fact if you think about, sort of step back from the whole question of what particular SETI experiment you're doing, you might say, "Well, how do you know whether there are aliens out there?" There are lots of ways you could conceivably know. You could look around and see if they're walking the planet. That's legitimate, although I don't think they are, but you know, you could ask that question. The second thing is you could look for astroengineering, for example. You could look for giant artifacts in space. I mean, the galaxy's been around for two or three times as long as the earth has been around, so if there are civilizations out there a lot of them?most of them?will be way ahead of us.
[Seth Shostak]
Seth has no particular affection for Neptune
Unless civilizations routinely destruct very quickly, they self-destruct because they invent technology and then they invent the H-Bomb and they blow themselves up. If that's what normally happens then maybe there aren't very old civilizations. But I'm more optimistic than that.
So a lot of civilizations could be way beyond us, so maybe they're doing stuff that you can see, that's obvious?you know, they're building something that's big. Let's see here, maybe they have giant rockets and you can see the exhaust from these rockets. Maybe the rockets have magnetic brakes and you can see the radiation from the magnetic brakes. People have thought of a lot of things. Maybe they've left, you know, giant monoliths on the moon for us to dig up, a la 2001. You know, it's not impossible. We wouldn't know, because nobody's really looked at the moon for those sorts of things.
So those are all possibilities. The trouble is most of them don't sound terribly fruitful because even though the aliens might be building big stuff, you don't quite know what to look for. I mean, how do you see it. There have been some experiments in that regime, I mean some people have done some things, they look for what are called Dyson spheres. Do you know what a Dyson sphere is?
Siduri: Um, I know of it only...
Seth: Take Freeman Dyson, you just roll him up like a marble and you have a Dyson sphere. No, Dyson spheres...
TCS: It's the Ringworld except a sphere world, right?
Seth: Yeah, exactly, exactly, which...turns out the Ringworld's a little unstable...
Siduri: I was about to say, I know of it from an old Star Trek text adventure game ["The Kobayashi Alternative"], where you went to visit a Dyson sphere world.
Seth: Yeah, exactly. You take apart some outer planet. Like Neptune?Neptune's not big in your life; you don't mind taking apart Neptune. They take it apart and rebuild it as a giant sphere, cover the inside with solar cells, for example, and that might be something that an advanced civilization might do. That kind of thing. People look for that, they look for Dyson spheres by looking for stars that have a lot of infrared. But you know, they've only looked a couple hundred stars. Not much is it?
So, there are all those approaches, but then people thought "well, maybe the best thing to do is look for signals." And the reason that got started is that a couple of guys, they were at Cornell University, a couple of physicists, just worked out really simple calculations. They said "If you take the most powerful radio transmitter on Earth, and our best receivers, how far apart can you separate these two things and still be able to pick up the radar transmissions?" And they figured, oh, well, it'd be, you know, thirty thousand miles or a thousand miles or something like that. And it turned out it was light years.
So they realized, hey, it's pretty easy to send a message that can go from here to another star. So maybe aliens are doing this. So that was 1959 and by 1960 people were already looking for the signals. Now, immediately other people said, well, maybe that isn't the only way to do it?maybe they'd be flashing lights at you or something like that. And it turns out that the physics tends to favor the radio. Mostly because, I don't know if you remember high school physics, but the amount of energy in a photon is proportional to the frequency of [Seth starts muttering equations]. Energy equals hf or [mumble mumble]. Anyhow, all that means is that light photons, a single light photon has got a lot more energy than a single radio photon. So if you want to send a bit of information from here to Alpha Centauri it's cheaper, in terms of the energy, to do that with radio than to do it with light.
So, you know, that's been the argument for many years. Now that argument isn't very solid anymore. I wouldn't even listen to this part of the tape.
"Next question."
Siduri: Well, I was gonna say, I have a list of softball questions from your biggest fan, and then I have a list of hardball questions. And one of the...
Seth: The softball questions are from my biggest fan? Is that my mom?
Siduri: No, I told you that there's a guy on the list that was a big fan of yours, and was all but asking for your autograph. And so I have a list of questions from him...
Seth: I hope he's not a Czech. [I think that's what he said. He was muttering again.]
Siduri: Hum?
Mark Territory: From Scotland?
Siduri: Uh, yes.
Seth: Scotland?
TCS: Paul from Scotland?
Siduri: Yes.
Seth: Paul?
Siduri: Um, he's just seen you I think, on like, radio shows.
Seth: Seen me on radio shows.
Siduri: Or, heard you on radio shows.
TCS: Heard you on TV. [Everyone's talking at once. I'm not sure this was what Splicer said.]
Mark: Might be a stalker, I don't know.
Siduri: But he's in Scotland, so I don't think you have to worry about him. But anyway, so one of the hardball questions was: "Our own civilization has only been using radio to transmit messages for less than a hundred years. Now these messages are increasingly being delivered in a digital, often encrypted form that is practically indistinguishable from white noise. What sense does it make to search the radio spectrum for such old-fashioned messages that we ourselves have only bothered using during this brief window?"
Seth: Good question, Paul.
Siduri: No, that wasn't Paul. That was Zach.
Seth: Good question, Zach. Next question.
No, no, no, he was absolutely right. I mean, if you look at the kind of signals that we're currently using, sort of spread-spectrum signals and things like that, they're very complicated, and they're completely unlike the kind of things we look for in SETI. The kind of things we look for in SETI are signals that are just what are called narrow-band signals, that are on one spot on the radio dial. So they take all the energy of the transmitter and pump it all into one small frequency range. Okay? You with me?
Siduri: Yeah.
Seth: All right. The advantage of that is that it makes it really easy to find the signal because all the energy is in a small band so it really stands out as a big spike of energy. Whereas if you spread it out over five megahertz, like a TV signal, then the energy's spread all over the band and it's very hard to find. But on the other hand, the actual signals that we use are spread out, more and more. And ET will be at least as advanced as we are, so you might say, "Well, why would they make those narrow-band signals?"
And the answer is, probably: most of the time, they don't. For their own internal communications they probably wouldn't do that. But if you have a beacon, which you want to hear at great distance?if for some reason they want to get in touch, or they're sending the galactic weather report, whatever, GPSs?there's lots of things that would have narrow-band components in the signal. So that's what we look for. But Zach has a point.
Siduri: So the assumption is that they would have to be kind of trying to get in touch.
Seth: They might have to be trying. Or, I'm not sure I would even go that far. If you asked Marconi a hundred years ago, what would he think the radio signals would be like in the year 2001, or whaddya think people will be using this technology for in the year 2001, he wouldn't have had a very good idea. He probably wouldn't have gotten it right?not much of it, anyway. So for us to say what kind of signals ET uses, a hundred thousand years ahead of us, what kind of signals he's producing?you could guess if you want. Probably not a very good guess.
I mean, one thing you always need is high-powered radar to look for incoming comets. Long period comets. Cause they can come in, and as you know, ruin your whole day. Land in Yucatan. But I mean, he has a point. It's just that we're looking for the signals that are easy to find.
[Mark Territory]
Mark follows TRUTH like a shark follows BLOOD
Mark: Are we also looking for the signals that might be accidentally broadcast?
Seth: Yeah, well, that's the question, and that's the question that Zach is really asking. And Shannon jumped to the conclusion, as she is wont to do, that we can only pick up deliberately broadcast signals. But you don't know what ET's using radio for, so...
Siduri [jumping to a conclusion]:
Seth: Yeah, we could trip on, as I say, a radar that they're using to warn about incoming Klingons, if you don't like radar warning about incoming comets. And in that case, then...
Mark: We'll get to those questions later.
Seth: And then you can say, "Well, it wasn't deliberate, but we got it anyhow," see. So in a sense SETI doesn't care. Yeah, what do we care.
How the Hell That All Works
"And if you don't hear ET there? Well, tough toe-corns."
Mark: Now, I imagine there must be many, many false alarms. Things that are picked up and determined to be background noise, anomalies, perhaps galaxies emitting natural things that while they have patterns, they're not signs of intelligent life. How do you determine whether a pattern is background noise or a signal?
[Seth Shostak]
Seth indicates where the ay-leens come from
Seth: Yeah, well, this is a question we get asked a lot?"Do you have a cryptologist or a cryptographer sort of looking at these things to say, well, this looks natural, that looks artificial?" In a way we do, although we really don't. We don't have any cryptographer. We can barely afford to have someone just clean up the rooms. The way it's done is, the nature of the signal itself is the decryption. If it's a narrow-band signal, that's something that's really easy to build a transmitter to make, but that's extremely difficult for nature to make. Nature doesn't make narrow-band signals.
I mean, listen to quasar with a radio telescope and you hear "PSHHHHH." It almost doesn't matter where you turn your knob, you'll hear that blank noise 'cause it's all across the band. Even if you listen to a pulsar, pulsars go on and on, maybe a thousand times a second, faster in some cases. But what you hear is "PRRRRR" or "PSH-PSH-PSH-PSH-PSH." It's still white noise. It doesn't matter where you're tuning your radio. You'll hear the pulsar, you see. Tune across a wide, wide range of frequencies and you still hear "PSH-PSH-PSH." So that's clearly nature because nature doesn't care about wasting a lot of energy. No person who was designing a transmitter would build one that sent ten pulses a second all over the band. It's a total waste of energy; it's bad engineering.
So that's how you do it, you say, "Hey look, if they put all the energy into a small region of the dial, that's something nature never does but transmitters do all the time." So that's how you tell.
Mark: Now, have we scanned the entire spectrum?
Seth: No, not by any means. We have only looked at a tiny fraction of the radio spectrum. Our experiment, Project Phoenix, which is run by the Institute?[pointing to a photograph on the wall] that antenna, the one in the middle?looks at more of the spectrum than any other experiment ever has. It's looking over from 1,000 to 3,000 megahertz. Each channel is about 1 Hz wide so that's like 2 billion channels for each star that we look at. That's still not the whole spectrum.
Mark: This is actually a question that came from one of our contributors. I don't know if it was Paul or Zach. They were under the impression that the signals are scanned for 300 seconds, approximately?
Seth: Yeah, that's about right.
Mark: How do you determine which bands to target first?
Seth: Oh, well, we just start at the bottom of the band and work up. How are you gonna know. If you start at the bottom of the band you may miss ET's transmission at the top of the band, yeah, but maybe if you start at the top of the band you'll miss his transmission at the bottom of the band. You don't have any information about that so you just?it's a matter of being methodical. We always do it the same way. Start at the bottom of the band and work up. It takes, you know, about ten to twelve hours to go through all those frequencies for any given star.
Mark: Yeah, but how much information is captured in that five minute window?
Seth: Well, in a five minute window you're listening to 28 million channels. So you're getting information about 28 million, actually, it's 56 million channels. It's 28 million frequency channels, but the receiver has?there are two polarizations that you're actually sensing, so there are actually two receivers in one at the focus, so it's actually 56 million channels. So during that five minutes you're looking for signals that are within those 28 million frequencies. And if you don't hear ET there? Well, tough toe-corns, move up and do 300 seconds on the next batch of frequencies. No ET? Go up the dial a little bit and do more, and that's the way it's done. And actually, observing one star isn't done at once, it's done in pieces, over the course of a couple days.
Siduri: I believe Paul's exact question was, "Ask how the hell that all works."
Seth: How the hell that all works. Well, what didn't I answer?
Mark: Perhaps you could start by telling us, once the data is collected by the telescope, where does it go? The project has been going on longer than hard drives have been in common use to store this data.
Seth: Mm-hmm.
Mark: Does it get printed out onto paper reels?
Seth: In the old days it was printed out on paper, yeah, it was. Not anymore. Those were the good old days. You could come in and there was only one channel, or ten channels, or some small number of channels, a hundred channels. So it was possible to put all the data out on a, usually a line printer. In the very earliest experiments it was just a strip-chart report. You know, one pen on a piece of paper. Maybe two, if you had two pole positions. When Frank did the first experiment in 1960, that's the way it was done. He just had a little motor that essentially turned the knob on the receiver and turned it up and down the dial, very slowly, you see, so the frequency was changing. And you could just look at the output. And he had a loudspeaker connected to it. It was all very simple. And then ten years later you could look through a hundred channels at once, so then you needed a line printer.
That was what was being used in 1977 at Ohio State, when some guy came in in the morning looking through the stack of computer printout, and saw one big signal and said "wow!" Wrote WOW next to it. The Wow Signal.
Mark: Can you talk a little bit more about that?
Siduri: Yeah, whatever happened to that?
Seth: Yeah, the wow signal. Well, it's pretty wow-y. But it doesn't seem to have been ET. Lots of people have gone back and they even, they immediately had a following beam on the sky that swept through that same patch of the heavens, just shortly after they got that signal, and didn't see it. And people have gone back there looking, you know, with more sensitivity, more frequencies, and nobody's ever found it again. So it's not good enough. It's like seeing a ghost in your basement once. It's not enough to believe in ghosts. If you see them every time you look, now that's okay, you might believe then. So it was undoubtedly some sort of interference.
Siduri: Is that the closest you've ever come to finding...
Seth: Well, how do you know? That's like pregnancy, I mean, are you close? It's not a matter of close, it's yes, it's a one-bit experiment. It's not that you're close. There have been lots and lots of false alarms. Particularly in the early days, because in the early days you would usually report the data. As you said, it was before hard disks. But what would happen is that you would go the telescope and you had a hundred channels, and normally you would just write everything to computer tape. Back with these big tapes, and you would put them on computers wherever you were, and play 'em back, and then look at all the data.
And you'd always find signals. You've got these huge antennas, you know, with very sensitive receivers, and hundreds of channels, thousands of channels, and now millions of channels, so of course you found signals. But then what did you do? What do you do with them? You could call up the local papers and say, "By the way, I found all these signals," and that would work the first time. But, well, how do you know it's ET? And you say, "well, I don't know." Then the next time you went back to Tucson you'd try to look at those parts of the sky again. And that's very tedious.
But now, what we do, is we check out all the signals right away, in real time. All the data's processed real time. So you don't leave the telescope with a stack of mystery signals. You know each one of them because you tracked it down. So in the early days there were lots and lots of these sorts of false alarms. Not anymore.
Mark: Does that mean that the sensitivity to signals may be less now than it was before?
Seth: No, the sensitivity's clearly better now. The sensitivity's better but the processing's better. That's just because, you know, digital electronics is better than it was. So now you can conceivably process everything in real time. That's the way it's done. When you're sitting down there in Puerto Rico, you're sitting at the control room, and the signals are coming in about?you get hundreds of signals every night. Hundreds. And each one of them is checked out. So far each one of them has been us.
Well it is rocket science, but it's not hard rocket science."
[Siduri]
Siduri trusts no one
Siduri: But now, I thought that was what SETI@home was doing.
Seth: Well, that's a different project. That's a Berkeley project. We process all our data, as I say, real time. And any signals that look like they're good are verified by a second telescope at Jodrell Bank, in England, just south of Manchester. We have a slow-speed line that sends the information about a handful of signals, whatever you have in those 300 seconds, sends that information to Jodrell Bank. And then they're looking at the same star. So here we are in Puerto Rico, and there they are in Jodrell Bank. And we're both pointing at the same star, so if we find signals here, then these guys spend the next 300 seconds checking those out. So they're always 300 seconds behind the Arecibo telescope.
Siduri: That's clever.
Seth: Yeah, and obviously, if it's really ET, you know you should be able to find it in both places. But beyond that, you're on the rotating earth, and if you do a little geometry you realize that, well, the motion of the earth means that these two telescopes are moving?with respect to whatever star it is you're looking at?at a slightly different rate, so there's a slightly different Doppler shift, so the frequency ought to be different here than there. A small amount, but it's easily measured, see, so there's a little microcomputer that does that simple high school geometry, and looks for that change in the Doppler shift. And if it doesn't find it, then it knows this is not ET: this is a telecommunications satellite. So that's another trick.
So they all get checked out. Now, SETI@home, that's data that's taken by the Berkeley crowd, on the same telescope but in a different way. And their data is of a nature that, you know, you can look at it two months later and still be interested. With ours, ours is so sensitive that if you found anything, you would want to check it out right away.
Mark: And how often does that happen? Do you get calls in the middle of the night, saying "check this out right away"?
Seth: Well, I'm usually sitting there. I usually have the 6 to midnight shift; Jill Tarter takes the midnight to 6 AM shift; Peter Backus comes in and spells one of us. You're actually there. And if it finds a signal, I mean, it doesn't?you don't get these giant klaxon sounds and red flashing lights. MM-NEE! MM-NEE! I mean, that would be great, that's what it is on Star Trek, but what actually happens is the workstation goes "beep." You barely notice it.
But then it says, you know, "I found these six candidate signals," it's a real signal. And what it does is, it sends them to Jodrell Bank, right. And if they come back from Jodrell Bank?almost always, they come back "sorry, Charlie, this is not it"?but every now and again something gets through the filter. So Jodrell Bank says, "Looks good to me." And meanwhile it's looking in a database of known interferers to make sure it isn't in there.
If all these systems are "go, this could be the big one," you still don't call up the airlines and get a ticket to Stockholm. Because what happens next is it, you know, "beep beep," it comes again. And you're still not paying much attention. But now what it's done, because it's found a signal that both telescopes think might be real, it breaks the observing. It stops going up the dial and it now moves the Arecibo telescope away from the star. Just a little bit. Maybe the diameter of the moon or something like that. Just that far away. And the signal ought to go away now. If it's really ET, if it's really coming from the star, the signal oughtta go away. Now, if the signal's coming from some telecommunications satellite that's wheeling overhead, that signal's bouncing all around, I mean it's so strong, bouncing around the telescope structure, it doesn't really matter where you point the antenna. You'll pick up that signal. So, if you point away from the star and you still get the signal, you know right away it's not ET.
But if it goes away, it might be ET. Or maybe the telecommunications satellite just went over the horizon at the same time. And that can happen too. So if it goes away, then you keep looking, and you move the antenna back on the star and see if the signal comes back.
Siduri: Does your heart start speeding up at about that point?
Seth: At about that time, if it goes off, and it goes away, then you pay attention. Because it's sort of fun. And you always set the sensitivity so this happens once every couple nights. And if it doesn't find it there and then it comes back and it does find it again, then, yeah, then you become more interested. And if it goes off and doesn't find it, then you're standing up. That doesn't happen very often. It's happened to me once or twice. That's when you get excited.
And at some point, you know, it'll do this half a dozen times, and then it sort of throws up its little computer hands and says, "I don't know what this is anymore. This is something you know how to decide. I don't know what to do next." I don't know, I think only once has it ever gotten to the point where the computer didn't know what to do next.
Siduri: While you were there, or...?
Seth: Well, I was downstairs, and we were observing simultaneously?No, we had a remote setup downstairs. I wasn't actually at the telescope. This was '97, I was at Greenbank, but the second telescope that we were using those days wasn't working that day, and that was how we got fooled.
Siduri: Ohhh.
Seth: But we got fooled for something like 16 hours. That was pretty interesting. It was very interesting to see how people reacted when it looked like this was the real thing.
Siduri: How did people react?
Seth: Everybody was simultaneously excited and nervous. That's true. Nobody went home, nobody went to bed. People just hung out. The engineers were all hanging around the computers downstairs. And I half expected that we were going to see the government show up. Everybody expects that the government would move in if we ever got a signal. But the government had no interest in moving in. Much to my disappointment. Even the local, the Mountain View government didn't want to move in. Nobody wanted to move in.
[We laugh. But, transcribing this, it occurs to me that a real conspiracy theorist could take this as proof that the government already knows about aliens! Because why wouldn't they react to an extraterrestrial signal, unless they had some way of knowing that it was a false alarm? And how could they know that, unless they already knew where the real aliens were? Hmm?]
Seth: I sort of hoped that the pizza guy would move in. We were getting hungry. But what did happen is that the media started calling up.
Siduri: How'd they know?
Seth: Somebody just called them. I mean, there's no secrecy, so, you know, they called up the New York Times. And they called me: "What about that signal?" I said, "Well, we're following one, but, you know..."
Siduri: So you would really know right away.
Seth: Oh, you would know right away. Yeah. In fact, I really do believe you would not only know right away; you would know before we had fully checked out the signal. Because how long is it going to take us before we believe it? I mean, surely within an hour or so you'd be beginning to get the idea that this might be it. But it still could be a software bug, it could be?you know, there are all sorts of things that can go wrong. It's an extremely complicated system. It involves two telescopes, it's a one-off device so needless to say it isn't fully debugged, and all that. So you'd say, "okay, this is looking interesting, but I'm not sure I'm going to tell the world I found ET yet. I'm going to call up somebody at another antenna, another radio observatory, and say, 'You check this out, with your equipment, not ours. Because you've got a completely different system, and maybe yours isn't buggy or whatever, if that's what it is.'"
And they would say, "Okay, well, we'll do that, but we can't get to it until tonight, because, you know, the star isn't up yet, or we have to change the receiver," whatever. So they'll spend some time doing that, it'll maybe take a day or two. And so surely, four days, five days can easily go by before enough have seen it to say "Okay, I'm willing to stake my reputation on it. This is for real." But long before that happens you'll be reading about it at Albertson's in the check-out line. That media won't wait; they'll run with the story before you've confirmed it. Everybody will, they'll be going "oh, the sky is falling, interesting signal!" So that's the way it will happen.
Siduri: So you actually do observation work on a regular basis.
Seth: Yeah, I go down there. We observe at Arecibo. These are some pictures I took; I didn't take that one, but this is what we were using when we found that interesting signal. In fact you can see the box over there, that trailer, that's Project Phoenix. That's in West Virginia. The other one's in Australia. So we get to use this for a couple weeks in the spring and a couple weeks in the fall.
Siduri: How many observers are there?
Seth: Well, we're doing SETI so we observe at night, because the sun would mess up these narrow-band signals, so for us it's better to observe at night. So we observe from 6 PM to 6 AM. We just break that into two shifts, from 6 to midnight and midnight to 6. So you only need two astronomers, actually, but usually there are three of us there?Jill Tarter, who was sort of the prototype for the Jodie Foster character; Peter Backus, who heads up the observatory operation; and myself. The three of us. But there are also a bunch of engineers. The engineers are much more valuable than the astronomers. The astronomers are pretty stupid, and the engineers are pretty savvy; they're much smarter than we are.
Mark: I have to ask, it seems like a false positive signal would be about the best April Fool's joke ever. Has it happened yet?
Seth: Oh, you mean where somebody would try and sort of hoax a signal? Yeah, well, we've thought about it, and maybe they have too.
Siduri: [laughing] Thought about it.
Seth: Well, we wouldn't do it, because it's very important that people have faith in our?that this is a good experiment, that's competently run, that's important to us, because we're running with their money, after all. So we have to do the best job we can, so obviously we're not going to make a hoax. But somebody else might. Maybe a couple undergrads would find it interesting to do that.
But it's actually quite hard because?you know, getting a signal into the Arecibo telescope probably isn't all that hard; you have to just walk up there with a transmitter and turn it on. You can do that, I can picture that. Of course it has to be in the right frequency bandwidth at, by the way, I might say, the right time, because we're only looking at a certain small part of the band at any given time, so you're gonna have to know all that, but it's not? well it is rocket science, but it's not hard rocket science. Yeah, they could do that, they could do that.
But the point is that they then also have to fool the guys in England. So they gotta?now it's becoming bit more involved, right, because now they have to have two telescopes that believe this signal. They've got to get the right Doppler shift, so they'd better know their geometry. And then they've got to be savvy enough to, when we do this very simple test where we move the telescope back and forth, to turn the transmitters on and off. So they essentially have to be, it really has to be an inside job, I would say, because they need to know what we're doing when. And I don't see it happening as an inside job. It's just not going to happen. But, you know, I won't say it's impossible. I think it's very, very hard. Very hard, but certainly not impossible. That's why you would check it out for a few days.
"I think that if you had real physical contact?I can't imagine that would be good."
Mark: There was another question Zach had.
Siduri: Zach has great questions.
Mark: Essentially the gist of his question was: by sending out radio signals into space, we may be able to alert other civilizations, other intelligences, that we are here.
Seth: Mm-hmm.
Mark: Is that a good idea?
Seth: Well, depends on how you regard the aliens.
Siduri: [quoting Zach] "Do you believe that the aliens would be friendly, and if so, why?"
Do you believe that the aliens would be friendly, and if so, why?
Seth: Yeah. Well, who knows, I mean I'm not a specialist on alien psychology, but then again who is? Nobody is. Nobody knows what the aliens would be like. About all you can say is that on Earth, aggression pays, a certain amount of aggression. And if you sort of look at the history of, you know, being found by more advanced civilizations, it usually doesn't work out in your favor. I mean, the Indians kind of welcomed the Europeans at first, but then they all got smallpox and things like that, I mean it wasn't a good deal. They got wiped out. And it wasn't just the disease, they got wiped out, you know, culturally.
The South Sea Islanders was always of interest to me. James, Captain James Cook's explorations. And he was under orders from the admiralty not to hurt anybody, and he by and large didn't. He almost never hurt anybody, and only when they did something pretty atrocious. He was only there to collect information. Nonetheless, when he lands in Tahiti or Fiji or whatever, these guys are sitting around, they're happy worshiping red feathers and rocks and things like that. And these guys sail into their bay, and they've got these big ships, and they've got cannons, they've got metal, they've got the wheel for goodness sakes?they've got all this stuff. And somehow after you've seen that, worshiping these red feathers just doesn't seem, well, that interesting anymore. These guys are clearly way ahead of you technologically, and they must be ahead of you spiritually as well, so whatever religion they've got is clearly better than what we've got.
You know, that kind of thing so rapidly destroys your culture. Now that's a situation where these guys weren't there to hurt anybody. So I think that if you had real physical contact?I can't imagine that would be good. And even in some sense, getting information might have some negative effects, if you understood it. Because if suddenly they're saying, "hey, here's all this science, here's all this physics, so guys who are doing all these research projects at Stanford Linear Accelerator, you can keep doing that if you want, but maybe you want to read this. Oh, the cure for death, yeah, that's over here too in this section, you might want to read that." That would be somewhat discouraging for a lot of people. But I don't think it will come to that. I don't worry about any of that.
Siduri: Why not?
Seth: Well to begin with, we are broadcasting out into space. You could say, hey, that's a dangerous thing to do. But SETI isn't doing that, I mean, that's not us. That's ABC and NBC, and if you're really worried about it, you should petition the networks to shut off their transmitters, because they may be only ensuring the destruction of civilization as they know it. I mean, you could do that; maybe you should. But I wouldn't worry even about that. To begin with, most of those signals are very diffuse. TV is on all the time, of course, and they are high-powered transmitters, but it turns out they don't deliberately broadcast in the direction of space very much. Advertisers don't see a whole lot of benefit.
So they don't do it. The military radar does broadcast out into space, that's much more detectable. But even so, we've been on the air for 50 years. The galaxy's been here for 10 billion years. Fifty years is a very small fraction of that. And in another 10 or 20 years we won't be broadcasting into space very much, because everything will be?you'll have a fiberoptic line coming into your house, you'll get your TV that way. So this is a very temporary problem.
Mark: But if we assume that an alien civilization is more advanced than us, and has done away with the need for this wasteful broadcasting using radio waves...
Seth: Then what are we listening for?
Mark:
Seth: Yeah, right, exactly, everybody's intimidated. Yeah, could be. That's been proposed as an explanation for why we haven't heard anything. They said, "Yeah, well the reason you haven't heard any aliens is because it's not a good idea to shout in the jungle." Right? Cause there's things out there that are bigger and have longer teeth than you do. It's not a good idea. There may be some truth in that, but again, this is sociology, so what do you know. But I do find it difficult to believe that all civilizations are that way.
You might say, "Okay, look. Broadcasting from our planet is not a good idea. We don't know what's out there. But putting a radio beacon over there, right, so that we can navigate over these short distances that we want to cover in our galaxy, that's not so horrible. I mean, they may find a beacon, but the beacon isn't where we are, the beacon's over there." Or you just send robotic vehicles out into space, and they don't transmit until they get very far away, or something like that. There are lots of ways to beat this rap.
And it may be that you feel you are the meanest dog on the block, you know, you just don't worry about this. You're the Galactic Federation, so you've got a license to do what you want. It's like the British navy. They're not afraid to take to the high seas. I don't know. It's all very interesting, and obviously very speculative. And you could say, you could talk yourself out of this, and say, "Nobody's ever gonna broadcast, it's entirely too dangerous." So then what do you do. Just don't listen? You don't get anywhere that way. At least if you listen, you have the chance of proving this thesis wrong in some way, and you have very interesting information if you find something.
So it's sort of like sitting around with Chris Columbus in 1492 and saying, "Forget the wooden boats, Chris. They probably won't work, and you won't find anything interesting anyhow." You could probably talk him out of it. But, you know, it probably was worth trying the experiment. But obviously, I work for the SETI Institute. We think it's worth trying the experiment.
"So that's kind of neat."
[Splicer]
Splicer looks into the Pattern, as
the Pattern looks back at him
TCS: Do you look at things other than the simple narrow-band signals? Do you look at the patterns that are created here on Earth, to see perhaps what you should be looking for?
Seth: Well, no, not so much, because keep in mind that in order?if there are radio signals washing over this room right now, as we expect that they are, then they're going to be weak. Because if they were really, really strong, probably we would have found them by now. There have been some surveys in the entire sky. And so if there were persistent, very powerful signals somewhere in the sky, those would have been found. So the expected ET signal is not going to be, you know, enough to cook birds at this distance or anything like that. They're going to be weak.
And in order to find weak signals one thing you can do is, as it were, make a time exposure. Just the way, with a camera, if you want to take pictures at night, you leave the shutter open for a long period of time and let the light build up. You can do that, and you can see very faint things that way. Astronomers do that all the time. But if for example you were making a photo of a pulsar, with a telescope that way, and you exposed the film for 20 minutes, then you wouldn't know that pulsar was flashing, would you? It would just be a bright spot on the film.
Well, we do exactly the same thing in the radio. We, as it were, integrate the signal over 300 seconds in order to build up the sensitivity. But that means if it's changing a hundred thousand times a second, or millions of times a second the way a TV signal does?all that's gone. It's all lost. So that's why finding the message is much harder than finding the signals; finding the signals you can integrate. What we do do is, we look at?we break up the data into one-second chunks, and we see if there are any pulses in there. Slow pulses. Beep. Beep. Things that are longer than a second in frequency. Then we would find those. We do look for those kinds of pulses. But nothing more complicated than that, because of the sensitivity.
Siduri: I think Steve was asking, though, if we were looking at what we're sending out there, just accidentally?
TCS: That's what I asked, although I think that Seth in his answer addressed that that was not...
Seth: I should have said...
TCS:
Seth: Right. What you're saying is that what we should be looking for is the kind of stuff that we send out?
TCS: Right, and you said that we wouldn't be able to hear the kind of things that we send out.
Seth: Yeah, what you could hear from Earth are powerful military radars?not very interesting to listen to, but powerful?or TV signals. You know, one-third of the power in the TV signal is from the carrier, which is this very narrow-band component of the TV signal. I don't know if you know this, but a TV signal is spread out over four or five megahertz?a big chunk of the dial. But there's a very sharp carrier component, which your TV set needs to tune in. So one-third of the power is going in there. And that's 10,000 times easier to find than the picture itself. So that's what you would hear from Earth, is carrier signals. Really big antennas could see I Love Lucy. You'd know that the TV transmitter is on, you just wouldn't know what show it is. If you want to know the show you'd need lots of antennas.
Mark: Is SETI looking at different kinds of modulation other than just amplitude?
Seth: Well, as I say, we don't look for really modulation at all, we just look for energy within a given band. The way it's changing...
Mark: Perhaps polarization changes, or...
Seth: Yeah, you could look for all that, those are ways to encode information on the message. But unless it's very, very slow?really slow?then we won't see it, because we just average everything. As I say, it's like taking time exposures. Take a picture of the city and you'll see that the stoplights have red, green, and yellow all lit up on the film. All the real information about how that's cycling is gone.
Siduri: Now, isn't there an optical SETI program starting up?
Seth: Yeah. There is. In fact, that's the Berkeley one; picture's over here. But there's one the Institute is involved with, and that's at Lick Observatory, down near San Jose. You ever been to San Jose?
Siduri: Uh-huh.
Mark: Nice drive up there. I wondered what those...
Seth: Mostly, they?actually, that's where a lot of these extrasolar planets have been found.
Siduri: Really?
Seth: Yeah. Geoff Marcy, who found probably more than anybody, works at San Francisco State, and Berkeley. But that's a telescope that he's been using. Now he's using the Keck telescope in Hawaii. But they still use this thing; they use it for a lot of stuff. Anyway, there's a telescope out there; I have a picture. There's a telescope up there with a one-meter mirror, and this young lady, Shelley Wright?she was an undergraduate, 23 years old I guess, or 22?she built a box to go in the back of this thing to look for flashing laser pulses. And so every night they use that telescope?not every night: those nights that it's available, which is about half the nights?they point it at nearby stars.
What they're looking for is flashing lights. And the reason this makes sense is because?I mean, you might think "Enh, that doesn't make sense, because the star itself is putting out a lot of light and that'll swamp any laser on a planet orbiting the star; you can't even see the planets, how could you possibly see somebody's laser?" Well, it turns out that if you take the most powerful lasers that we could make, the ones they have at Lawrence Livermore and places like that, that if you aim that laser into a mirror that's the size of this table or something, and then aim it at a nearby star, and put all the power from that laser into a billionth of a second flash, you see, concentrating the energy in time now, then for a billionth of a second that laser will outshine the star.
Siduri: Oh wow.
Seth: Yeah. So, what she does is, she just looks for a billionth of a second and looks for a bunch of photons coming in. It wasn't originally her idea, but that's the experiment we're involved in. And that's kind of neat, because nobody's really done that much before, so you could maybe find something. Maybe some alien civilization nearby has a big laser, and they've just got a little mirror assembly for the output of the laser, and it directs the light onto a big mirror [mutter mutter]. But, you know, they just ping each star that's near them for five seconds a day or ten seconds a day. They don't know which ones might have civilizations, but they just do this, automatically. And then all we have to do is get a lot of people looking at a lot of stars and we'll see some that are pinging our way. So that's kind of neat.
Siduri: How long has this been going on for?
Seth: It's been going on for about six months. I mean the idea of looking for flashing lights in the sky is not new, but actually doing it is new.
I mostly use my FreeBSD box for programming. I don't even use X that much. I am curious as too how far I would have to clock down a newer processor so as to not need a fan at all. Not many ideas for the PSU other than moving it though.
As FreeBSD has showen (working closely with Apple) being BSD allows for co-operation with industry, which can be advantagous, however If a company choses to close the source completely then they can simply be ignored. Conversly if they wish to implement a partially open operating system (as apple have done releasing the code under the terms of thier own licence) then the BSD is flexible enough to allow them to do this, whilst still contributing code back to the community under the terms of the BSD.
A small clarification: OS X is actually Mach with a BSD unix layer on top. I to however wish to see more varients as I feel that they generaly increase quality, dispite the traditional 'less unix acceptance due to too many venders' argument, as this is normally only taken by comercial vendors.
As always people being comparing KDE and GNOME on appearance. THEY ARE BOTH CUSTOMIZEABLE. Stop whinning, this post was about the new features of QT 3, not about KDE vs GNOME, which is an impossible argument to wage as both have strengths and weeknesses, but please in future please don't claim one is better than the other on the strength of their default look and feel.
I find it intreguing that he was prosecuted under oregons own computer crime law, which is rarely used, so much as one law for all.
things like this are really positive for all our high security OS's out there. Hacking/Cracking is an extremely positive activity when put to actally helping me secure my box.
Being of the BSD camp I don't much care what the proprietry venders get up to, I and many others won't be paying any attention.