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New Distributed Project Seeks Gravity Waves
fenimor writes "Much like the popular SETI@Home distributed computing project that searches radio telescope data for signs of extraterrestrial life, the new Einstein@Home will search for gravitational waves in data collected by U.S. and European gravitational wave detectors. Albert Einstein's General Theory of Relativity predicted the existence of gravitational waves in 1916, but only now has technology reached the point that scientists hope to detect them directly."
http://einstein.phys.uwm.edu/
Posting as AC to avoid karma whoring.
It would be another confirmation of Einstein's theory. Some more background here.
And here's some about a recent satellite also hoping to establish the existence of gravity waves.
Here's what I do: Bitty Browser & Andromeda
If you detect gravity waves from sources like supernovae, black hole collisions, etc. you're confirming that Einstein's GR works and that the properties of the waves (ie amplitude, duration) make sense for that particular source.
If you can detect primordial gravity waves from the very early universe(harder!), you now have an indication that inflation (rapid expansion) of the universe is a reasonable cosmological model rather than its current somewhat ad hoc status. It nicely explains away some problems with simpler models, but no real direct test has been performed to show that it happened.
I used to run seti@home 24/7 until i realized that half of my electricity bill was from keeping my computers on all the time. I still run it when i'm using my computer (like right now) but turn off the comp when i go to bed and when i'm at work.
Laser Interferometer Gravitational Wave Observatory from Caltech is working on same subject. LIGO will search for gravitational waves created in supernova collapses of stellar cores (which form neutron stars and black holes), collisions and coalescences of neutron stars or black holes, rotations of neutron stars with deformed crusts and the remnants of gravitational radiation created by the birth of the universe. LIGO is a joint project between scientists at the California Institute of Technology (Caltech) and the Massachusetts Institute of Technology (MIT), sponsored by the National Science Foundation (NSF).
The kickass OpenGL screensaver it gives you!
The BOINC versions of Seti@Home and Climateprediction are similar.
You can attach to all of them and have the client devide your CPU time any way you want.
BOINC also has a folding client (predictor@home), but there's no eye candy.
Sorry, gravity probe B (the recent satellite) is not trying to confirm the existence of gravity waves. GPB is looking for "frame dragging," another predicted effect of general relativity. Gyroscopes in GPB should precess, despite the fact that they are over the poles of the earth and (to first order, excluding motion about the sun and the motion of our solar system itself) not in a rotating frame. Even though the gyroscopes won't be in a rotating frame, their spacetime metric will be 'dragged' by the rotating massive earth, causing a precession of some parts of arcseconds (check the web page for more).
-Leo
Detecting gravitational waves isn't the same as detecting the pull of gravity (that we've been doing for a long time). There is an analogy to electromagnetism - the attractive or repulsive force between electric charges is like gravity's pull, but light (electromagnetic waves) are analogous to gravity waves. General relativity predicts that accelerating mass can generate ripples in spacetime (gravity waves) that can carry away energy. There's a good bit of evidence that says the ripples are there (for instance, binary pulsars seem to spiral toward one another at just the rate that would be explained by the loss of energy to gravity waves), but the waves themselves have never been detected. Detecting gravity waves would be an excellent test of general relativity, for one. It could also give us new ways of looking at events in the cosmos, similar to the way in which radio astronomy revolutionized the study of the universe.
1) Any theory in contention with either of these would probably only be an alternative to one or the other, considering that GR and QM make predictions on completely different scales and are generally not unified.
2) GR does not make any prediction such as "in the far field, gravity waves should look like the result of dipole excitations" or quadrupole. In the far field, in a linearized patch of spacetime (a small patch of it, in which special relativity can be applied) gravity waves should obey a linear wave equation. Therefore, both binary inspiral sources such as coalescing black holes or other massive objects and any other gravity wave source are superimposable and can therefore be predicted by GR.
3) Be careful with the usage of the words dipole and quadrupole: a binary inspiral system is not actually a dipole, since both bodies have the same "sign" - the gravitational force only cares about energy density. Two massive bodies both have positive energy density.
-Leo
Gravitational Radiation being much weaker, thus harder to detect, does not interact with matter like the electromagnetic radiation does. As a result, gravitational waves produced by spiraling binary star systems, coalescing stars, supermassive black holes etc will be unaltered when detected giving us a completely new perspective in how we look to the universe. It will be like the transition from optical telescopes to x-ray ones.
An excellent, popular book about the topic is Black Holes and Time Wraps by Kip S. Thorne, one of the participants in the LIGO project at Caltech and a well known theorist.
In the case of imaging invisible celestial objects , consider that, for example, Black Holes are by definition invisible, they do not emit electromagnetic radiation ( short of, if we forget the Hawking Radiation ) so astronomers predict that a Black Hole exists by observing the effects ot its existence to the surrounding stars. With gravitational radiation detectors a more direct method will be available. Plus, there exists the dark matter issue ( and others ), an extra tool would be nice to have.
PS. Gravitational waves from the inflationary phase of the universe ( if there is such ) will be too weak to detect.
PS2. From a more theoretical point of view there are some alternative theories ( quite serious ) like the Brans - Dicke theory, they include also a scalar field that propagates in the form of a wave as well. If i recall correctly, in this case the polarisation is different so i think ( but i am not 100% sure ) that if such fields exist a detector like LIGO will able to tell.
At Leiden University in The Netherlands a project called MiniGrail tries to detect gravitational wave produced by neutron stars.
No. There is no antigravity in Einstein's gravity. And even if there were with negative mass or exotic matter to produce local antigravity effects, detecting gravitational waves still would not help acheive that goal.
They should have written an actual Mac OS X application before advertising their project to the public. Even within the constraints of users who don't mind using the Terminal for manipulating and launching processes it is inadequate. In the terminal the first thing it did after using chmod +x to make it executable was come back and request the URL for the project. Say what? There is nothing in the documentation that I could find indicating something like this would be asked. Then after proceeding a bit further it indicated it could not find the choices I had made to the parameters it uses to govern how it will run so it set them to defaults!
I'm supposed to trust these amateurs with my Mac? If they don't have the needed programming knowledge they need to get it and do so before inflicting unnecessary havoc on unsuspecting voluteers. Take a look at Folding@Home or SETI to get an idea of what you need to have done before you ask the public to trust your work.
It's a holdover. People used to post relevant but obvious information in an attempt to get their karma number as high as possible.
Stuff like how Einstein@ home is running on BOINC, which also runs SETI@home
http://boinc.berkeley.edu/
so it should be pretty stable. Anyone who read the articles or attempted to sign up would know that, but most of the mods didn't do either.
They were playing the Karma game, back when karma was permanently accrued and displayed. People got their Karma numbers up into the tens of thousands at the height of the out-of-controllness. The pinnacle of Karma Whoring was re-posting the article text from the linked article. It was useful if one person did it, but the text would be reposted hundreds of times for every story, with everyone trying to be the first to repost.
Playing this game eventually became socially unacceptable. It became good mojo to post certain things annonymously, like direct download links or article texts, to reassure everyone around you that you weren't just being a jerk, that you really did post the information because you wanted to help.
Then they instituted a Karma cap at 50, which helped a lot. Still, people complained that a single post with +4 informative, -1 overrated could cause your Karma to go from 50 to 49. And other people were still playing the Karma game, just with multiple accounts. So they expunged even that amount of resolution, to the current good / great / bad system. And now many people don't even know what Karma Whoring is, or why one would do it.
I respect the grandparent poster for posting annonymously. He's clinging to antiquated morals, which is kind of heartening.
The ______ Agenda
http://folding.stanford.edu/faq.html#project.own