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BOINC Project to Search for Gravitational Waves
Buzz Skyline writes "Einstein@Home is a new, BOINC-based distributed computing project that will analyze data from the Laser Interferometer Gravitational wave Observatory (LIGO). The goal is to perform a whole-sky, gravitational wave survey of pulsars. Beta-test versions of the Einstein@Home screen saver should be available by the end of the summer, and final release is planned for early 2005."
It's actually quite obvious where the name came from. LIGO is a Michelson interferometer that uses a laser to detect gravitational waves. There are other kinds of gravitational wave detectors, such as resonant bar detectors.
Boinc should open up more distributed computing projects as well, since the server/client infrastructure is mostly prewritten. Since my other Boinc projects have been sputtering and not giving me work lately, maybe I'll give this one a try. More info on Boinc Here
Even those who arrange and design shrubberies are under considerable economic stress at this period in history.
For one thing, on most of the workstations BOINC would appear to work very quickly on the data only to crash out well before the computation was created. Indeed, sometimes it would actually crash before any data was processed by the application. At other points it would work for hours and hours without actually achieving anything; closing down the workstations at the end of the day without getting one computed dataset off was quite frustrating. On the workstations that were actually computing datasets we discovered a few started to become bloated past the point of peak functionality within a few months of even casual use.
While it's possible that it's the inhouse .NET code that could be creating the problem, after several weeks of debugging we're pretty sure it's BOINC related. My suggestion is to steer clear and look for a safer and more reliable API (or roll your own).
Try not. Do or do not, there is no try.
-- Dr. Spock, stardate 2822-3.
Yet another version of AMOR... Talk about number of choices. For those who do not know: AMOR stands for Amusing Misuse Of Resources, its one of the toys for KDE.
No. You'd have the effect before the cause would be visible. The cause, however, would still precede effect.
No, for at least some moving observers you do wind up with the effect preceeding the cause. It's all part of relativity. Two observers moving in opposit directions can dissagree about the order of two events. If anything exceeds the speed of light one of the observers will see the effect preceed the cause on the time line.
There is no such thing as "simultaneous", it's all relative.
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- - You can't take something off the Internet! That's like trying to take pee out of a swimming pool.
As written up at the back of Wired mag a few years back.
http://www.geo600.uni-hannover.de/
Picture two tubes, each exactly 600m long and at 90 degrees to one another in the horizontal plane. Bounce a laser beam off a mirror at the end of each one. The time should be identical. Unless there is a gravitational pulse, in which case one would appear shorter than the other.
Or maybe this is something completely different =)
No, I did not read the f***ing article!
Several companies have tried to create a commercial grid software setup that pays users for their contributions. None of them have taken off. They have trouble getting customers because they don't have an existing user base waiting to crunch. (It makes your sales a little more difficult when you can't say "We can get started immediately." Instead they have to say "If you pay us money, then we'll be able to go out start trying to get all those end users to sign up.")
The end users meanwhile don't want to sign up to run endless amounts of "test packets" that aren't accomplishing anything. (They obviously don't start getting paid until there's actually customers to crunch for.) It also doesn't help that these companies' software was also kind of bloated and quirky.
The lure of being able to materially contribute to real science, in areas that are typically underfunded, by donating only idle CPU cycles is quite strong. People will do that for free. The minute you start making them focus on it as a business venture, they start getting very picky and a lot less tolerant.
I don't think you're wrong, I think there will be some pay-to-crunch type systems existing in the future. But I think they will only be branches off an existing donated network (like Seti@Home). I really doubt anyone will be able to start one from the ground up as a business model. BOINC might be a place to start, but it would need some serious modifications.
For one thing, the BOINC credit system is based on what the end users' computers self-report. Each client software runs benchmarks of its CPU, and then based on the amount of time it took to finish a Work Unit, reports back to the server how many CS (credits) it should be granted. To guard against cheating, the server will send out the same Work Unit to 3 clients, and all 3 clients will only be granted the smallest number of credits of what the 3 individuals claim.
It will probably work well most of the time, because you have millions of users, and no real incentive for most of them to cheat. The probability of the same packet being sent to 3 different cheaters is fairly small. (And even if all 3 WERE cheaters and got more credits than they deserved, it doesn't REALLY matter, does it.)
But in a commercial setup, 100% of your end users have an incentive to cheat. (If you're getting paid $1.50 per credit, it's in every end users' interest to claim as many credits as you can get away with, regardless of how long it actually took.)
But regardless, I think distributed computing projects are going to be taking off dramatically in the next few years, paid or otherwise. It's going to be pretty exciting to see the kinds of crazy things people will start wanting to crunch with it.
Moving to BOINC can allieviate this paranoia. The new BOINC infrastructure includes the ability to use the "Anonymous Platform," which means you get to compile on your own code and simply retrieve the workunits from them. All the source is available if you don't trust the project.
If we can send a faster-than-light signal, we can exploit relativity to send signals into the past.
First, we need to realise that 'simultaneous' is a relative concept. Consider three evenly spaced spacecraft flying past you in a line. The centre ship fires lasers at the front and back ships, and when the beam reaches them they explode. Simultaneously? No: the lead ship is flying directly away from the beam, while the tail ship is flying towards it, so the ship at the back blows up first, and the ship at the front blows up later. But from the point of view of the captain of the centre ship? Both the other ships are stationary relative to him, so the beams reach them simultaneously.
In general, events that are simultaneous for one observer will not be simultaneous for an observer in relative motion.
Let us now suppose that we wish to cheat on the Alpha Centauri state lottery. At time t=0 in the frame of reference of Alpha Centauri the draw is made, and an instantaneous signal is sent to Earth with the result. The signal arrives at time t=0 (Earth is in the same reference frame, because it's not moving at any significant speed relative to Alpha.)
So, from the perspective of observers on Earth or Alpha, event A (signal sent from Alpha) is simultaneous with event B (signal received on Earth).
However, simultaniety is relative. Let us post an agent in a spacecraft moving at high speed relative to Earth and Alpha, such that from his point of view event A takes place after event B. This is quite possible, as we saw above in the example of the simultaneous shootings. Now when we receive our signal on Earth we relay it - instantaneously - to our agent, who then relays it - again instantaneously - to Alpha Centauri, allowing us to know the result of the lottery ahead of time and buy a guaranteed winning ticket.
Conclusion: instantaneous signalling buggers up causality.
Real Daleks don't climb stairs - they level the building.
Comment removed based on user account deletion
For a while I worked as a research programmer for one of the General Relative Groups working on the GEO600 Gravitational Wave Detector in both the UK and Germany. GEO600 is a UK and Germany co-project.
The interferometer is a typical Michaelson interferemoter using lasers with two orthogonal branches 600 metres in length. These gravitation events are small. Movements are ~10-E24 metres. It is expected that only one or two events a year will be detected. So it must run 24/7, 365 days a year.
Naturally you have to remove as much of the noise from the data as possible to detect an event. Mirrors are hung on glass threads as they are thermally inert. It runs in a vacuum. It is temperature controlled. Everything is monitored from air pressure to sisemology. The amount of data being produced is incredible. I assume LIGO is the same hence the distributed analysis.
GE0600 uses a microwave link to transmit data from the site to Hanover where it is backed up and fat pipes pass it on to partner universities. The 'head end' on site uses triple redundancy and enough bufferage for 24 hours back-up on site.
You are talking many gigabytes a day and many terabytes a year and some where in this lot will be an event. This is truely the domain of super computing or distributed processing.
Of course, even LIGO which is larger, is unlikely to spot many events if any and we will probably have to wait until LISA, the NASA/JPL/ESA spaced based interferometry project is up and running to get decent results.
Erm, our current understanding via Einstein's general theory of relativity is that gravity waves move AT the speed of light. Among other things, this avoids causality problems. Some efforts have been (and are being) made to prove this, and early indicators are that this is so, though we await conclusive testing.
See the following reference.
Allow me to point you to Folding@Home. This is Stanford's distributed computing project. Their goal: to understand protein folding, protein aggregation, and related diseases.
I'm sure they've been mentioned before, but they seem to meet your four criteria nicely:
a) The second question in their FAQ is "Who owns the results"
c) A Linux Console version is listed on theirDownload Page along with Windows and Mac OS X versions.
b) In my experience, I've had to do nothing but install and let the software do its thing. It only takes up unused cycles and is completely non-intrusive. For Mac OS X users, I recommend checking out TeamMacOSX's website for some free software downloads that make it easy to maintain clients for multiple processors.
d) Science!
SharkJumper
Spacetime diagram doesn't work out for this one, unfortunately... Think of a light-cone centered on Earth and another one centered on Alpha - they cross at a point a few years in the future (and physically at the midpoint between the two systems). So, yes, if Alpha draws a lottery, and sends the info to Earth instantaneously, the Earthlings have it a couple years before the light of the lottery-drawing event reaches Earth.
However, they turn around and beam the message back to Alpha Centauri. Time has still passed (even a miniscule amount of time, if they had an auto-receive/reply machine on Earth that takes the beam from A and turns it around immediately to send back). When the message is received at Alpha Centauri, it's received *after* the drawing took place, and *after* they sent the message to Earth. However, they're receiving it several years before they would know that the Earthlings would normally know about the result - so it seems like the Earthlings are "predicting" the lottery, but they're always telling the answer just a little too late.
In any case, the spacetime diagram in this instance works better if you take it as a generic... The 45-degree lines in an ordinary diagram represent light-speed. However, if you're including infinite-speed gravity waves as a method of transmitting data, then your "cone" has to open up to 180-degrees: every event, no matter how distant, that happens simultaneously can be known to everyone, no matter how distant. And no problem with causality, just that light is too slow to keep up with "real-time".
Highly unlikely, though - there are bigger problems than causality in relativity that constrain information (not just light) to travel no faster than light.
-T
Tom van Flandern is a well-known crank. He has done some good science in other areas, but his conclusions regarding the speed of gravity are just plain wrong. For corrections of van Flandern's mistakes, see this paper, and also this discussion.
The speed of gravity has been indirectly measured to be equal to the speed of light within about 1% accuracy, by observing a binary pulsar system (whose rate of inspiral due to loss of energy from gravitational radiation depends on the speed of that radiation); the 1993 Nobel Prize in physics was awarded to Taylor and Hulse for this work. Direct measurements will become possible once LIGO or one of its peer or successor experiments detect gravitational waves.
That's what the BOINC project is all about.
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