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SETI@home Explained, From Inside
eheien writes: "The IEEE currently has an article detailing SETI@home, written by the project founders. The article goes into a great deal of detail on how SETI@home works, how sensitive the search is to signals (it can detect a cell phone on Saturn's moons), how successful it has been, and so on." It's a good read, and has some impressive numbers about the project that most SETI@home participants may not have realized.
for awhile, i had 5 linux machines running packets 24/7.
about the time i hit 1000 data packets processed, i learned that they were accepting money from the co founder of microsoft.
that's a little like taking maney from organized crime...so i pulled the plug/couldn't care less now.
but it was interesting to learn how to set up all the boxes, diald, etc., plus there was always the hope of something significant happening.
i checked over at distributed.net but it was looking pretty yawnish, and california was getting hit with a heat wave and was dipping low into the barrel, so i just packed it up.
if something interesting for distributed stuff comes up again, and energy sanity has returned to california, i might be interested in bringing everything back up.
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FIRST POST!
It seems to me that the point of SETI@home is that even this (relatively) basic search is consuming enormous amounts of CPU cycles. Searching for signals more complicated than this is just not technologically feasible yet.
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umm, unfortuantly, I don't run distributed software for the sheer thrill. I run it to win the damn money. Who says I am going to, but I compare it a lot to the lottery. I don't have to pay w/this and I have a lot better odds of winning (like 1 in 1800). SETI I don't win anything and it may even cost us our lives (key word is MAY) in the future when we start fucking up the lives of other worlds not just our own...
:)
:)
I will stick to what is harmless and could give me money
No dorky clubs for me where I compare how much CPU time I wasted going to a program
As to composite signals from several stars: yeah, right. Composite signals from two or more places converge into intelligent signals in at the most one place. It is a fair bet that lifeform capable of sending interstellar signals know some basic geometry. Setting that place to be earth would make no sense unless they knew that we are here and were only trying to reach us.
Even if we could only detect one part of this "composite" signal it would still definetly be irregular enough to qualify it as an alien communication. This is essentially what seti@home is looking for. It is not trying to decode anything, just detecting irregularities that might implicate intelligence..
Non-consecutive frequencies? What does that have to do with anything. Seti@home picks frequency bands and distributes those as chunks to work on. If someone should happen to send a signal modulated at a frequency higher than half of the bandwidth of those chunks it would not really matter! It would create a sideband and only this sideband would show at some other chunk. This would definetly be an irregularity that sets off all kinds of alarms and people would start to investigate more.
How the hypothetical aliens encode their message is totally irrelevant to seti@home. If there is a transmission method besides modulation of electromagnetic radiation it is also irrelevant to seti@home. If, however, this transmission can be received with a radio telescope it is more than likely that seti@home will catch it. Even if it catches only a part of some wierd pattern it is enough. We don't need to know more than a fraction of the message to know that something is being sent and for this seti@home is more than well equipped!
The SETI project makes an assumption that because Hydrogen is the most abundant element in the Universe it follows that a transmission from another species would necessarily be at that frequency. The other species would choose to transmit on the frequency that is most likely to be listened to. Although this assumption may make sense to us, it does not necessarily follow that it will make sense to another sentient life form on another planet. It is essentially attempting to predict the behavior of a species about which we know nothing other than they are sentient and have developed technology.
We must consider the possibility that another species would choose to broadcast on another frequency. The reasons for choosing another frequency may be cosmologically or mathematically significant. That is, since we do not have a complete theory of the everything (unified theory), we may not yet recognize that there would be a better frequency for broadcasting. One that would be the most obvious choice to a species that had already developed a unified theory. Therefore SETI may be looking at the wrong frequency.
Another siginificant issue is the power required to send the transmission any significant distance in Galactic terms. I won't get into that (because I can't remember the stats of the top of my head) but suffice it to say, that it would require many more times the power generated on earth every day.
Frylock: That's not a toy!
Master Shake: You say that about everything you own. You should own toys. They're fun.
You know, just semi-offtopic, but that Windows screen saver app SUCKS. My PIII-733 linux box with the text client completely blew the doors off my Win2k PC running the stupid graphical screensaver client even though they were both running 24/7. I don't remember offhand but I believe my linux box could do 4+ blocks in the time my Win2k PC did 1 (24 hours!!) WTF. That 3d display must be really inefficient.
it can detect a cell phone on Saturns moons
:-)
Hang on, the only way to be sure of this is to have tested the hypothesis. That means they're picking up cell calls on Saturn's moons. Doesn't this strike anybody else as being perhaps odd? I know Vodafone are on a campagin of world domination, but I didn't know they had bought out telcos out there!
Los Angeles - Jan 12, 2347
After burning through approximately 2.12E678 CPU hours of computer time in over three centuries of existence, SETI@Home is finally calling it quits.
Their search for extraterrestrials has foundered, producing only a few candidate signals per year, none of which has ever been proven to be of extraterrestrial origin. Says Lars Pendelson, current project president: "Yeah, we just can't see going on when they are more practical applications of the technology".
Those more practical applications were discovered recently when the SETI@Home team discovered a promising possible alien signal was actually a cell phone call placed by an astronaut on the Saturn space station. Lars comments, "Yeah, we were really pissed about that one - we had the code geeks working overtime decoding that one, only to discover it was some bloak talking dirty to his girl on the Saturn space station. But at least we found a practical application for the technology".
Beginning next month, the SETI@Home space array and orbital server farm will be redeployed routing cell phone traffic for Mars, Saturn, Jupiter and the asteroid belt.
Users of the SETI community were understandbly dissappointed that their pet project was going away. The slashdot community in particular was in an uproar, having just recently narrowly edged out Team Microsoft in a heated, centuries long stats battle.
Lars knows that the user community will be let down, but hopes that they realize that finding ET is an "utterly hopeless and wasteful quest." He continues, "It's just plain stupid to waste all this equipment, when cell phone service in the outlying solar system is so poor."
The article says:
Our search for extraterrestrial intelligence assumes that an alien civilization wishing to make contact with other races would broadcast a signal that is easily detectable and easily distinguishable from natural sources of radio emission. One way to achieve these goals is to send a narrowband signal. By concentrating the signal power in a very narrow frequency band, the signal will stand out among the natural broadband sources of noise.
Ok, now, if the little green men have a headstart on us, and they are smart enough, why don't WE SMART EARTHLINGS not broadcast to THEM a powerful narrow frequency signal? If our guesses here are right about their higher intelligence, they probably have better resources for computing and will be able to process whatever it is we're sending... And all that, given that some gov body on earth is willing to invest in a project where a signal is being transmitted for over 50 years from earth towards space, and is willing to understand that IF the signal is being received and translated, a response will come in YET ANOTHER 50 years (And notice my optimism about the distance in light years, and in cycles of response!)... well, if such a goverment existed, it would be in Amsterdam, where pot is legal :-)
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Skaag.
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If "communicate" means a dialog, then obviously we aren't -- it's forbidden by the laws of physics. But even if we lucked out and found aliens 5 or 10 light-years away, the speed of light wouldn't be the important thing. The important thing is that we'd have nothing in common. The galaxy has existed for billions of years, so there's no reason to think we'd both happen to discover radio technology at almost the same time. A randomly chosen intelligen species is likely to be either millions of years ahead of us or millions of years behind us in development. If we were a million years ahead of them, they wouldn't be doing radio. So most likely they'd be so far ahead of us in terms of development that it wouldn't be a two-way dialog where we both have profound thoughts to offer each other.
Is there any point? Don't be silly. Discovering intelligent life elsewhere in the universe would be the most important intellectual event of the last thousand years.
maybe we should work on traveling these kinds of distances in space first.
What's your logic? Radio is fairly easy. Physical travel across interstellar distances is ridiculously hard. The energy required to accelerate a 100-ton space ship to 10% of the speed of light would be about 10^20 joules, which is hundreds of times greater than the entire world's annual energy budget. Sending people to Mars isn't even likely to happen within the next 100 years.
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> The assumption is that ETI would use radio
> because the laws of physics prohibit anything
> faster, but if that's true, why would they even
> bother?
Well, we have been sending RF garbage into space since Der Fuhrer hosted the Olympics in 193X, regardless whether or not it was feasible to be sending people to Alpha Centauri or it was too far away to really talk to Little Green Men. Bets are that ETI has been doing the same thing as well.
"Don't mind me cutting myself on Occam's Razor"
As long as they don't bounce the signals off our own satellites, everything is okay.
As long as they don't bounce the signals off our own satellites, everything is okay.
"Don't mind me cutting myself on Occam's Razor"
So what are the roaming charges for Saturn's moons?
Schwab
Editor, A1-AAA AmeriCaptions
...there will be a SETI@Home story posted on /. and ET will finally make him/her-self known to the masses:
:)
ET (ET@QUADRA-5.EAM3002.GALAXY.NET)
FIRST POST!
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I think the more interesting thing than the technology behind seti, is the sociology.
:)
Thousands of people are using it, religiously. I've been running it since it came out, i've overclocked my computer father, upgraded my processor, and even went so far as to install it quietly on the server farm at work
I'm not sure if people are in to it because they Dig feeling like part of the worlds largest computation (information age mob mentality?) or simply because we're incredibly lonely and, more often than not, thourougly dissapointed in the human race. The fact that you have seti at home clubs and organizations, people hold personal meetings to discuss how many work units they've burned in the last month (I guess thats the other factor... what better way to flex your hardcore box), Almost outweighs the fact that you can hear cell phones on saturn... besides, from what i hear, the long distance rates from there are deadly.
Fortunately, searching for signals in a data stream from a radio telescope is an easily distributed task. We can break up data from an observation into frequency bands that are essentially independent of one another. In addition, an observation of one portion of the sky is essentially independent of an observation of another part. This lets us divide a large dataset into small chunks that a personal computer can analyze comparatively quickly. In this way, we can distribute the work to people willing to donate their spare CPU cycles.
Yes, this will catch most signals directed at us. But, what if aliens are sending a composite signal from several stars? Also, what if the aliens are sending a signal whose principle is as yet unknown here, and it occupies nonconsecutive frequencies?
The point being the data should be examined for more than one kind of pattern, and patterns introduced and/or obliterated by the distribution network should be accounted for.
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This article doesn't seem to go into any real new detail. The only interesting data is that they seem to be trying to expand their search by adding a new telescope. While this is a great idea, the SETI@home project can only do so much crunching.
The problem to date, to my mind has been that the processing is too front end intensive. This project should do rough curve fitting first (ie do quick calculations on client computers, to find a general idea of the curve) and then select areas of interest to farm out more signifigant data to client computers. But that's just my opinion.
who knows, with 10 gHz possibly on the way, this discussion may be a moot point as I send it.
hmmmm?
is there really any point to have this project. even if we find intelligent life (and i am willing to bet that the odds are a LITTLE against us) how are we going to respond or communicate if they are 150 light-years away. by now they probably have forgotten that they have sent the message. maybe we should work on traveling these kinds of distances in space first.
Good question.. this is what the SETI program is trying to find out. That question is like asking "can we go to the moon" around 1930. Many people seem to think it's possible, and have theories to support them. Many don't, and have theories to support their positions as well. Obviously in the 1950's it was pretty clear that we could, even without actually accomplishing the feat, changing the problem from one of theory, to one of engineering.
I really don't think that SETI will find any signals (note, this is a nearly completely groundless position, based solely on gut feeling). I also think that it would be criminal to miss a chance to communicate with another intelligent civilization, simply by not listening.
Doug
Venn ist das nurnstuck git und Slotermeyer? Ya! Beigerhund das oder die Flipperwaldt gersput!
I know seti@home has been rather popular, but I see from some of the posts here, as well as many friends & co-workers, that people are growig bored with the client. there may have been 2.1M volunteers, but I'm sure a fair percentage, if not a majority, have dropped off the seti wagon in favor of other screensavers.
that's not to say SETI@home isn't doing great, I hear they've even been in the situation of not having enough work units to send out, but this whole project could be made into something much bigger, much grander.
I sure S@H could be looking at this data with more precision than they are currently, through numerous refinements to the search criteria and formulae. The limit is only in how many cpu cycles they can reliably expect. I believe the volunteer membership base could be doubled with one very minor refinement to the graphical client: by briefly blink-highlighting canditate signals in the 3axis bar graph gizmo. The article mentions that they've accumulated 1.1 billion candidate signals to date. You can be relatively certain that if you've completed even 1 data unit, you found one of these signals.
It seems to me that the eventual boredom with the SETI@home client is due to the almost complete dearth of feedback or accomplishment. the information displayed on the client is interesting, but it changes very slowly and in a completely predictable way. The simple psychological reward of blinking a triplet or a phased pulse when a canditate signal is hit would go a long way towards providing the rewarding sense of accomplishment people seems to be hoping for out of this project. This simple new feature would not interfere with the science and hardly slow down the typical cliet computer, so I say please!~ add this feature!
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I guess I'm only a Fudboy, looking for that real Transmeta
Being able to detect a cell phone as far away as one of Saturn's moons is actually pretty lame. Remember, the intercity of a wave in space is relative to the square of the distance. So, if you tried to find something a thousand times the distance of Saturn to earth, it would be a million times weaker. Saturn is only about 1/14,000th of a light year away. IIRC the nearest star is about 10 light-years away. So, in order to year a signal from there, you would need a transmitter about 140,000^2, or 19 billion times as powerful as a cell phone. Take that out from 10 light-years to 100 and you'll need 190 billion times more power then is used in a cell phone.
I don't know how many objects exist that close to earth, but I don't think its that many. While there very well may be something out there, sending signals, I seriously doubt that it will ever be picked up by seti at home.
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That's a good idea, but there are a ton of dreamers (such as myself) that will continue to plod away and use SETI regardless of the feedback I receive. Bluntly, I use SETI completely in the background (no screensaver), and run it all the time. To me, it's more important the feeling knowing that I am a part of a larger whole, and working on something that I would really like to see happen within my life. Just the proof that intelligent life exists, just the little part that I play in the search, is meaningful to me. And besides, it's not like I am using those cycles for anything useful, now.
As the song goes:
"So remember, when you're feeling very small and insecure
How amazingly unlikely is your birth
And pray that there's intelligent life somewhere up in space
Because there's bugger all down here on Earth"
--"The Galaxy Song", Monty Python's Flying Circus
"Don't mind me cutting myself on Occam's Razor"
Conversely, I realized that I could have been easily hoodwinked by a great sounding operation that I understood (basically) only on faith! I guess the lesson here is caveat downloader!
The real importance of detecting a single alien signal is to start a new global war economy, we must be prepared to fight back the bad aliens, right? imagine how much cash NASA would receive for the space program, imagine how much cash would be available for the nations so they can do they own research. I don't think answering the real question "Are we alone" is the point.
This article is a very nice description about what seti@home does, but the question is: Does it even have a chance of working? The assumption is that ETI would use radio because the laws of physics prohibit anything faster, but if that's true, why would they even bother? Most likely they would be too far away to really talk with wouldn't they?
Their damned cell phone wouldn't work a block from the store I bought it in. (I know the store location has nothing to do with tower positions, but still, it's the principle of the thing).
-josh
Let's crack useless encryption keys instead!
"And like that
It seems to me that the eventual boredom with the SETI@home client is due to the almost complete dearth of feedback or accomplishment. the information displayed on the client is interesting, but it changes very slowly and in a completely predictable way.
Yeah, I always thought they should add an "ET Counter" that displays the total number of aliens your computer has found so far!
"And like that
So, I wonder, are WE transmitting a repeating signal at 1450 Mhz or near it? If WE are not transmitting a distinguishable repeating signal near 1450 Mhz, why would we expect anyone else to?
"Wait! There's something coming through in the harmonics!"
"What is it?"
"It's hard to say, I can only decode one letter at a time. I'll send them to the screen."
YHBT, YHL, HAND.
"But what does it mean?"
dave