Question about SETI...

[Ducky]

So the basic idea is point radio telescopes at stars systematically and listen for responses, right?

How does the Earth's movements around the sun and the "wobble" of our revolutions daily affect the reception? Is it reasonable to think that we could listen to the same star over and over and only recieve a signal at one point in our orbit?

If this is true, how does SETI propose to compensate for this? Or am I misunderstanding something?

 

[CaveDave]

AAUI, it is all now passive listening: they are simply using recievers to look for signals that fit within parameters they expect would indicate possible artificial (read: intelligent) sources.

SETI itself uses telescopes around the world on a time share arrangement with all the other projects.

SETI@Home (not the same outfit) has a piggyback antenna at Arecibo, and records constantly without interfering with other ongoing projects there, and uses idle machine time of volunteers worldwide to analyse the data. (I let them use my machine, along with Einstein@home [gravitational wave astronomy] and Predictor@Home [analysis of folding in protein sequences])

For the @Home stuff see:
http://setiathome.berkeley.edu/
or
http://boinc.berkeley.edu/

Or for SETI itself:
http://www.seti.org/site/pp.asp?c=ktJ2J9MMIsE&b=178025

Cheers,
Dave

 

[Grundar]

They seem to be able to compensate for for the rotation of the earth and that is a much faster change in star position over time then what the earths orbit around the sun causes. So i don't think they have a problem compensating for the slower effect.

It should just be a programming problem for the ones responsible for the positioning of the telescopes.

/Hans

 

[Ducky]

AAUI, it is all now passive listening: they are simply using recievers to look for signals that fit within parameters they expect would indicate possible artificial (read: intelligent) sources.

SETI itself uses telescopes around the world on a time share arrangement with all the other projects.

SETI@Home (not the same outfit) has a piggyback antenna at Arecibo, and records constantly without interfering with other ongoing projects there, and uses idle machine time of volunteers worldwide to analyse the data. (I let them use my machine, along with Einstein@home [gravitational wave astronomy] and Predictor@Home [analysis of folding in protein sequences])

For the @Home stuff see:
http://setiathome.berkeley.edu/
or
http://boinc.berkeley.edu/

Or for SETI itself:
http://www.seti.org/site/pp.asp?c=ktJ2J9MMIsE&b=178025

Cheers,
Dave

Thanks Dave! I actually am a seti@home person, as my previous (and current) pcs run the screen saver that does the computations for them. I did, however, think they were the same org.

 

[SezMe]

So the basic idea is point radio telescopes at stars systematically and listen for responses, right?

Well, "listen" is probably misleading. They are simply looking for a narrowband signal that might indicate the presence of a intelligence. For example, consider a radio signal. It has a "base" frequency which carries the power and the modulation that carries the signal. At this time, all SETI can do is look for the carrier, the narrowband signal that might indicate that something else is there as well.

I got to spend 3-4 days at Arecibo during one of the SETI monitoring periods. It was all quite interesting. I can point you to a book written for the layman (layperson?) if you are interested in more.

 

[Ducky]

Well, "listen" is probably misleading. They are simply looking for a narrowband signal that might indicate the presence of a intelligence. For example, consider a radio signal. It has a "base" frequency which carries the power and the modulation that carries the signal. At this time, all SETI can do is look for the carrier, the narrowband signal that might indicate that something else is there as well.

I got to spend 3-4 days at Arecibo during one of the SETI monitoring periods. It was all quite interesting. I can point you to a book written for the layman (layperson?) if you are interested in more.

I am interested. Thanks

 

[SezMe]

Go here. Don't be put off that it is a book aimed at children. It is a very good intro to the subject for anyone who is not technically oriented.

That person on the cover is Jill Tarter. She is the woman who served as the model (so to speak) for the main character in the book and movie Contact.

 

[Ducky]

Go here. Don't be put off that it is a book aimed at children. It is a very good intro to the subject for anyone who is not technically oriented.

That person on the cover is Jill Tarter. She is the woman who served as the model (so to speak) for the main character in the book and movie Contact.

Well I am a sound engineer, so I am somewhat technically oriented. But I'll have a look. Thanks.

 

[TobiasTheViking]

Just wanted this here for reference, please correct me if i said something wrong

12:25:12 <TTC> fowlsound: as for your SETI question. The speed, orbit, direction and position of earth is irrelevant when it comes to monitoring for EM
waves from other stars/planets
12:25:24 <fowlsound> howso toby?
12:25:32 <TTC> the paralaks can be used to find the distance, but besides for that, it doesn't really matter
12:25:47 <fowlsound> I would imagine moving out of direction from the wave would cause loss of recrption?
12:25:51 <El_Spectre> is the red/blueshift from earth moving noticable?
12:26:12 <TTC> because the difference between C and earths movement make any errors in frequency casued by earths movement so ridicously small that it
doesn't matter
12:26:40 <fowlsound> hmm
12:26:44 <fowlsound> interesting.
12:26:45 <TTC> the instruments already monitor a range of frequencies within a band. so all the earhts movement can do is make the frequency not
200000000000 but 20000000001
12:26:47 <TTC> hz
12:27:02 <TTC> though it would probably be less than that
12:27:12 <fowlsound> ok so our loose reception compensates.
12:27:21 <fowlsound> that makes sense
12:27:28 <TTC> now, if you are looking at the wobble of stars, to see if they have planets around them, then it matters
12:27:29 <TTC> but that isn't seti
12:28:01 <fowlsound> indeed
12:28:06 <fowlsound> Thanks Tobi
12:28:06 <TTC> fowlsound: not only that, but even if you are wihtin 0.5hz(or some number way way WAY bigger than the difference caused by earths movement)
of the signal, you will still be able to pick it up(though not as strong as if you were directly on it)
12:28:21 <TTC> just like when you tune a tv or radio station, you can hear it before(though with static) you actually reach the channel
12:28:31 <fowlsound> yeah I was thinking that.
12:28:44 <fowlsound> now why can't I be smart like Toby?
12:28:49 <TTC> both that, and the fact we are monitoring a band of frequencies makes it totally irrelevant
12:28:54 <TTC> you are, just in different areas
12:29:00 <fowlsound> LOL possibly
12:29:01 <TTC> talk about sound equipment and i'm totally clueles
12:29:10 <TTC> ok, not totally, but not as proficient as you
12:29:16 <TTC> and my spelling sucks compared to yours '
12:29:19 <fowlsound> well but that is sound equipment, which bothered my why I didn't know the answer to that
12:29:20 <TTC> paralaks.. wtf
12:29:30 <fowlsound> lol
12:29:40 <TTC> hehe, not really sound equipment, reciever equipment. Not sure if they overlap for you
12:29:54 <El_Spectre> it's all waves man
12:29:55 <fowlsound> they should, honestly.
12:30:10 <TTC> i'll just paste this to the forum, for other people
12:30:19 <fowlsound> thanks Toby

 

[SezMe]

Well I am a sound engineer, so I am somewhat technically oriented. But I'll have a look. Thanks.

As a sound engineer, you are probably ahead of this book so it might not be for you. But give it a look-see.

As a sound engineer, you are well ahead of me, although I have dabbled in DSP software.

 

[CaveDave]

Thanks Dave! I actually am a seti@home person, as my previous (and current) pcs run the screen saver that does the computations for them. I did, however, think they were the same org.

I just discovered:
There is a James Randi Edu. Fnd. group that can evidently be joined at the BOINC site. I have tried to join, (but my name doesnt show up yet) and I think we all should. Darat and Asthmatic Camel are two names I recognized on the list.

Cheers,
Dave

ETA: When you search for a group, use "randi" for the search term: "JREF" will come up with a Japanese team. There are two Randi teams, one has only 1 member, so I picked the other one.