Frequently Asked Questions about SETI@home

FAQ Categories

  1. Getting Started
  2. Running SETI@home
  3. Performance and Credit
  4. The Project
  5. Windows-specific
  6. Platforms
  7. SETI@home Data Distribution
  8. SETI@home Science
  9. SETI in General

If you cannot find your question below, please submit it.


Getting started

  1. What do I need to participate in SETI@home?
  2. Do I need to know anything about science or SETI to use SETI@home?
  3. How long will it take to download the screensaver?
  4. I pay by the hour for Internet connection. How much connect time will SETI@home need?
  5. What about security?
  6. How complex is the software? Will users have to get involved with switching it on and off, or sending off the results? Will my computer have to be on-line the whole time?
  7. I downloaded the software but my computer doesn't know what to do with an .exe/.sit/.hqx/.tar file - what do I do?

Running SETI@home

  1. The graphics don't move. Won't it burn into my screen?
  2. If I turn off my computer while SETI@home is running, will it lose any data?
  3. Can I run this on as many machines as I like using the same SETI@home login?
  4. Can I run SETI@home while using a different screensaver?
  5. Does SETI@home work through firewalls (or proxies)?
  6. I have SETI@home set to run as my screen saver, but it keeps getting interrupted right after it starts running. What's going on?
  7. The client reports that it is unable to connect to the server. On Windows 95/98/NT machines this is sometimes seen as a WinSOCK error number 10060. What's happening?
  8. Does SETI@home support proxy authentication?
  9. How do I change my login address/user info?
  10. Why does only part of the SETI@home window appears on my screen?
  11. Will running SETI@home overload or burn out my CPU?

Performance and credit

  1. How can I make SETI@home run as fast as possible?
  2. Why do some work units take very little time to complete?
    Why did the progress bar suddenly jump to 100% only part way through the analysis?
  3. Will the screensaver program use more than one processor on a multiprocessor machine?
  4. According to your stats page platform X is running Y times faster than me! Why?
  5. When I returned my results and got a new work unit, why were the "Data units completed" and "Total computer time" values not updated?
  6. I'm trying to access my account, but I've lost my password. The e-mail address I used when registering is invalid. Is there any way for you to give me access to my account?
  7. Will I get credit if the signal is detected using my computer?
  8. Will SETI@home run faster with more RAM (e.g., 256 MB instead of 128 MB)?

The project

  1. Why don't you release the source code?
  2. Why aren't you doing this in Java?
  3. Why are you doing this as a screensaver instead of a background task that runs all the time?

Windows-specific

  1. Is the Windows screensaver password protected?
  2. SETI@home uses 90% of the time on two CPUs. Why does it do this if it's not multithreaded?

Platforms

  1. Are there versions of SETI@home for parallel systems such as Beowulf or multiprocessors?
  2. Will there be a Windows 3.x version?
  3. Is there a version that runs as an NT Service?

SETI@home data distribution

  1. Will you ship larger chunks of data to faster computers?
  2. What happens to work units that never get returned by us? Are they lost forever?
  3. Can I use a disconnected PC?
  4. If you don't get a result back from one PC how long does the server wait until sending the same data out again?
  5. How can I return my results but not get another work unit from the servers?

SETI@home science

  1. What happened to the gaussian information display in the new Mac and Windows clients? Are the clients still looking for gaussians?
  2. What will happen if an extraterrestrial signal is detected?
  3. It says SETI@home will run for 2 years. Why not keep it going indefinitely?
  4. If you find a signal, how will you decode the information in it?
  5. How is data collected from the telescope and transmitted to other machines for analysis?
  6. What sorts of signals are being analyzed, and what form does the signal analysis take?
  7. How will the results of the calculations be merged again?
  8. Are there any safeguards in place that would prevent the sending of a false 'negative' interpretation of data, thus masking an extraterrestrial signal?
  9. What is to prevent someone from hacking the program and sending back false data that would interpret a signal as extraterrestrial?
  10. Is it likely that so many people sign up that you won't always have enough Arecibo data to feed all the clients? If so, how will this be handled?
  11. Why is curve fitting done for some FFTs and not others?

SETI in general

  1. What sort of spectrum is currently being emitted by earth? Is that signal visible say 10 or 50 light years away? If SETI were on a planet say 10-50 light years from here and running this project there, would it be able to detect earth's signal (assuming it was looking in our direction)?

If you couldn't find your question above, and would like to submit this question to us, please go here.


What do I need to participate in SETI@home?

For Windows systems (95/98/NT) you'll need a computer with at least 32 MB of RAM, the ability to display 8-bit graphics in 800x600 resolution, 10 MB of disk space, and an Internet connection (dialup is OK). For Macintosh systems you'll need the above, as well as a PowerPC processor and Mac OS 7.5.5 or later. You can use SETI@home on a laptop that is connected sporadically. We also support many versions of UNIX, including Linux on various CPUs. We hope to eventually support other systems such as OS/2 and BeOS. We won't support WebTV. There are no CPU speed or modem speed requirements. It doesn't matter where in the world you live.


Do I need to know anything about science or SETI to use SETI@home?

No. All you need to do is download and install the client software.


How long will it take to download the screensaver?

About 5 minutes over a 28.8Kbps modem.


I pay by the hour for Internet connection. How much connect time will SETI@home need?

SETI@home connects only when transferring data. This occurs once every few days and lasts for about 5 minutes. All of the processing is done off-line.


Why are you doing this as a screensaver instead of a background task that runs all the time?

SETI@home uses a lot of memory while it's running, and it would cause swapping on some computers. We want to make sure it has zero impact on your normal computer work. So, for PC and Mac, the default mode is screensaver.

However, if you already have a favorite screensaver, or prefer not to run a screensaver, SETI@home can also be run as a background program that computes all the time and has no graphics. The UNIX version works like this.


Why aren't you doing this in Java?

It's not currently fast enough, and there are lots of system-dependent details that we need to handle in C.


What about security?

The client/screensaver is available for download only from this web page - we do not support SETI@home software obtained elsewhere. This software will upload and download data only from our data server here at Berkeley. The data server doesn't download any executable code to your computer. All in all, the screensaver is much safer than the browser you're running right now!


Will the screensaver program use more than one processor on a multiprocessor machine?

Not the initial version. Maybe a subsequent one.


Why don't you release the source code?

We decided not to make source code available for security reasons and for science reasons as well. We have to have everyone do the exact same analysis, or we can't have any control over our research and be confident in our results. We were also worried that there may be a few people that want to deliberately try to screw up our database and server.


How complex is the software? Will users have to get involved with switching it on and off, or sending off the results? Will my computer have to be on-line the whole time?

Users will not have to do anything if they don't want. The results can be sent automatically, next time the users are on the internet (checking their mail, surfing, etc), or it can be set to ask permission before logging on to the internet.


Does SETI@home work through firewalls (or proxies)?

SETI@home uses the HTTP protocol, and work through any semi-transparent firewall that allows outgoing Web traffic. The latest versions of SETI@home should work through more restrictive firewalls and proxies.

If you are having problems connecting through your proxy, you could also look into SocksCap by NEC at http://www.socks.nec.com/sockscap.html and Hummingbird Socks at http://www.hummingbird.com/products/nc/socks/index.html Both let you use software as if it were "directly connected to the Internet".


I downloaded the software but my computer doesn't know what to do with a .tar (or .hqx or .sit or .exe) file - what do I do?

Windows software is packaged in files ending with .exe, Mac software with .sit or .hqx, and UNIX with .tar - chances are you have downloaded software for a system other than yours.


The graphics don't move. Won't it burn into my screen?

On most monitors, no. To make sure, Select the "Go to blank screen" option under Screensaver Settings.


Can I run this on as many machines as I like using the same SETI@home login?

Yes, you can - and as long as you use the same login on each machine, you'll get credit for them all.

Please note that you can (currently) only run one SETI@home process on a Windows or Mac machine, and if you are running multiple SETI@home UNIX processes, they must be running out of different directories. To setup these directories simply install the UNIX client as you normally do, but install into a different directory each time. Now you can run multiple SETI@home UNIX processes by starting one instance of the client from each SETI@home directory.


What happens to work units that never get returned by us? Are they lost forever?

We keep track of every work unit that goes out - if it is taking too long getting the results back, the server will automatically send it out to somebody else. Only after we get results back and confirm them we will remove the work unit from disk.


Can I use a disconnected PC?

No. In theory it would be possible to transfer data and results on floppy disks, but we're not supporting this.


If you don't get a result back from one PC how long does the server wait until sending the same data out again?

It varies. Our goal is a week.


How can I return my results but not get another work unit from the servers?

Copy any file into your SETI@home Data directory and rename it "stop_after_send.txt". On the Macintosh, the "SETI@home Data" directory is in the Preferences folder, inside your System folder; on UNIX and Windows it is in the same directory as the executable file SETI@home.exe. If you later want to get a new work unit, remove the "stop_after_send.txt" file.


According to your stats page platform X is running Y times faster than my platform! Why?

This boils down to the vastly different speeds of different processors. As well, UNIX versions don't have any graphics (yet) and therefore run much faster. You can speed up the Mac and Windows processing by selecting your screensaver to "blank" after a few minutes, thereby reducing the graphics overhead. In addition, there was a bug in early Windows version (before 1.05) that caused it to report incorrect CPU times.


What happened to the gaussian information display in the new Mac and Windows clients? Are the clients still looking for gaussians?

The clients are still looking for Gaussions, however rather than display information about gaussions all the time, in newer clients the information only appears if the client has found a gaussian strong enough to report back to us.


I have SETI@home set to run as my screen saver, but it keeps getting interrupted right after it starts running. What's going on?

The SETI@home client may be being interrupted by another screen saver or screen saver-like program. As SETI@home is designed to be as noninvasive as possible by only using your computer while it is idle, if the client detects another program that wants to run, SETI@home will quit and step out of the way. If this other program is another screen saver or some other application that waits until your computer is idle before running, both SETI@home and the other program will try to run when the computer is idle causing SETI@home to quit. One common application which shows this behavior is McAfee VirusScan. If you have VirusScan installed, make sure that you have turned off the ScreenScan portion of the application as this will interfere with SETI@home.


How do I change my login address/user info?

If you need to change anything other than your e-mail address, you can use this web-based form: Account Change.

If you need to change your e-mail address, you must have access to the old account, since this is where we'll mail your password. If you don't have access to your old account, or you mis-typed your e-mail address when first logging in, you will have to log in again as a new user with the correct e-mail address.

For both security and administrative reasons, we cannot process any account changes unless you use the Account Change form.


Is the Windows screensaver password protected?

Our screensaver works just like any other screensaver, which includes the ability for the operating system to enforce password protection. This is done through the normal password protection channels.


SETI@home uses 90% of the time on two CPUs. Why does it do this if it's not multithreaded?

One CPU is doing graphics and the other is doing data analysis (so actually it is multithreaded, in a limited way).


Does SETI@home support proxy authentication?

Not currently (version 1.06). This feature will be added to a future version.


The client reports that it is unable to connect to the server. On Windows 95/98/NT machines this is sometimes seen as a WinSOCK error number 10060. What's happening?

Due to overwhelming interest in the SETI@home project, the server may intermittently be unreachable as too many clients are trying to connect. The server may also be occasionally down for maintainance. If you are unable to connect, please wait an hour and try again.


When I returned my results and got a new work unit, why were the "Data units completed" and "Total computer time" values not updated?

When we receive the results of a completed work unit at our server, it is transferred to a separate computer for processing. There may be a delay of up to a few days before the results are assimilated and verified. Your credit is updated only after verification of the work unit results data. Once the server has updated your statistics, your computer will receive the revised values the next time it connects to the server. This means that your displayed statistics will generally lag behind the work actually done.


Are there versions of SETI@home for parallel systems such as Beowulf or multiprocessors?

No. You can parallelize SETI@home by running multiple instances of it, either on a multiprocessor or on the nodes of a cluster. Just make sure that each instance runs in a different directory.


Will there be a Windows 3.x version?

Not a graphical one. We may be able to do a command-line (DOS) version.


Is there a version that runs as an NT Service?

Not currently. We hope to have one soon.


Can I run SETI@home while using a different screensaver?

Yes. In Preferences, select "Data Analysis Always Runs". Select a different screensaver. SETI@home will run, even while the screensaver is running.


I'm trying to access my account, but I've lost my password. The e-mail address I used when registering is invalid. Is there any way for you to give me access to my account?

In order to protect your account from modification by others, we require both your e-mail address and password for access. If you lose this information, we unfortunately cannot help you access your account or your credits. You will need to create a new account with a valid e-mail address to access any future credit.


What will happen if an extraterrestrial signal is detected?

A procedure has been agreed upon by SETI researchers around the world. First, other SETI researchers will independently verify the signal. If the signal is real and can't be explained by man-made sources (satellites, reflections etc.) then press agencies and governments will be notified in a systematic way.


Will I get credit if the signal is detected using my computer?

Yes. Our software keeps track of where each piece work is done. If your computer is involved in the detection, you will, if you wish, be listed as a co-discoverer.


It says SETI@home will run for 2 years. Why not keep it going indefinitely?

In 2 years the Arecibo radio telescope will have scanned the part of the sky visible to it three times, and SETI@home will have analyzed this data. That's enough for our purposes. And by then there will be new telescopes, new experiments, and new approaches to SETI.


If you find a signal, how will you decode the information in it?

Our goal is simply to find the signal. If it contains information, it may require experts in linguistics or mathematics to decipher it.


How is data collected from the telescope and transmitted to other machines for analysis?

Data is recorded on high density tapes at the Arecibo telescope in Puerto Rico, about one 35 Gbyte tape per day, then mailed to Berkeley, then divided into 0.25 Mbyte chunks which get sent from the Seti@Home server over the internet to people around the world to analyze. Arecibo does not have a high bandwidth internet connection, so data must go by snail mail to Berkeley at first.


Will you ship larger chunks of data to faster computers?

No, all computers receive the same size chunks. Faster computers will finish each chunk faster, then immediately get a new chunk to work on, so we'll keep them busy all the time.


What sorts of signals are being analyzed, and what form does the signal analysis take?

We search for strong narrow band signals. It's like tuning your radio set to various channels, and looking at the signal strength meter. If the strength meter goes up, that gets our attention. More technically, it's a lot of digital signal processing, mostly Fourier Transforms at various chirp rates and durations.

We also search for pulsing and drifting signals, and signals which match the antenna beam pattern as the telescope slews across the sky. The analysis software searches for signals about 10 times weaker than any search done to date, because it makes use of a computationally intensive algorithm called "coherent integration" that no one else (including our Serendip program) has had the computing power to implement.


How will the results of the calculations be merged again?

They are merged in a database using our computers here, interference is rejected, and various pattern detection algorithms are applied to search for the most interesting signals.


Are there any safeguards in place that would prevent the sending of a false 'negative' interpretation of data, thus masking an extraterrestrial signal?

Yes. Without going into detail (for obvious reasons) we have a mechanism that detects forged results.


What is to prevent someone from hacking the program and sending back false data that would interpret a signal as extraterrestrial?

See the above question. Besides, it wouldn't matter - if there's a "hit", we will analyze that chunk of data ourselves to verify it.


Is it likely that so many people sign up that you won't always have enough Arecibo data to feed all the clients? If so, how will this be handled?

It's possible. Up to a point, we will handle it by sending the same data to more than one user. Beyond that, if we can afford it, we will set up another data recorder at Arecibo and record a wider frequency range (our current system records only 2.5 MHz out of SERENDIP's 100 MHz bandwidth).


Will running SETI@home overload or burn out my CPU?

No. The CPU on most computers is always executing instructions (often the operating system's "idle loop") whenever the computer is turned on. It's no additional strain to execute SETI@home.


Why does only part of the SETI@home window appears on my screen?

In response to many requests from our users, SETI@home will now run on systems with screen resolutions smaller than 800X600 pixels. But if the window is larger than the screen resolution, parts of the SETI@home display window may extend off the edge of the screen; if this happens, move the window around to see all the data, or set the display to a higher resolution.


How can I make SETI@home run as fast as possible?

Select the "Blank screen after 1 minute" option under Screensaver Settings, and select "Data analysis always runs" in the Preferences dialog. Minimize the application window.

Will SETI@home run faster with more RAM (e.g., 256 MB instead of 128 MB)?

SETI@home uses about 16 MB of RAM while it's running. Beyond a certain point (typically 64MB, more if you run memory-itensive applications) more RAM won't make it run faster.


If I turn off my computer while SETI@home is running, will it lose any data?

No. SETI@home writes its results to disk every minute or two.


Why is curve fitting done for some FFTs and not others?

If time resolution does not yield 64 or more time bins, or if the slew rate is out of bounds, the curve-fitting routine is not called. In the curve-fitting routine, if a Power of Time array has no bin above 3 sigma, skip that array. For each bin (i.e., each candidate Gaussian) if amplitude not above 3.2 sigma (mean recalculated to exclude peak) skip that bin.


Why do some work units take very little time to complete?
Why did the progress bar suddenly jump to 100% only part way through the analysis?

Occasionally, a work unit will contain strong radio interference; these strong interfering signals typically come from satellites and radar from our own civilization. If the interference is very strong, the SETI@home program can not analyze that part of the spectrum, and after trying for a few minutes and detecting thousands of strong signals of earth origin, the program stops early in the processing and gets a new work unit. You will still get credit for the work done.


What sort of spectrum is currently being emitted by earth? Is that signal visible say 10 or 50 light years away? If SETI were on a planet say 10-50 light years from here and running this project there, would it be able to detect earth's signal (assuming it was looking in our direction)?

Earth is polluting space with radio and television signals that might be detected by nearby advanced civilizations, but it would be difficult for such a civilization to discover these signals if they only have Earth's current level of technology (eg: if they have an Arecibo like telescope and SETI@home like search).

Early TV shows like I Love Lucy and Ed Sullivan left the earth about 40 years ago, so have gone out 40 light years, reaching several thousand nearby stars. But these signals are relatively weak and SETI@home is not likely to detect the equivalent of Earth type TV transmitters, even on the nearest stars.

Earth's strongest transmitters might be somewhat easier to detect, such as those emitted by military radars, or some radio telescopes. The Arecibo telescope transmits very powerful signals when it is used as a radar system to study planets, asteroids and the ionosphere. These radar signals are powerful enough to be detected 10,000 light years away by searches like SETI@home, except for three big caveats:

a) The Arecibo transmissions are in a very tight beam (they are not omnidirectional, like TV and military radar), so they only cover a very small part of the sky at once (about a millionth of the total sky). It's is unlikely another civilization will be within one of these narrow beams.

b) The Arecibo transmitter's oldest signals left Earth about 30 years ago, so have only travelled 30 light years.

c) SETI@home is not searching the band of frequencies that the Arecibo transmitters utilize (although our older SERENDIP III program did survey one of those bands).


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