Gravity wave astronomy finally on trackl

Status
Not open for further replies.
E

enigma10

Guest
<i>It would also usher in a new type of astronomy - one that is not dependent on the observation of light. This is necessary because most of the cosmos is "dark"; the majority of its matter cannot be seen with traditional telescopes.</i> <br /><br /> So, instead of looking at the light produced in the sky, we'd be using light to look for subatomical changes?<br /><br /> As much as it would be nice to confirm the existance of a "gravitational wave", i just dont see this doing the job. <div class="Discussion_UserSignature"> <em>"<font color="#333399">An organism at war with itself is a doomed organism." - Carl Sagan</font></em> </div>
 
T

tom_hobbes

Guest
I agree, very exciting! <div class="Discussion_UserSignature"> <p><font size="2" color="#339966"> I wish I could remember<br /> But my selective memory<br /> Won't let me</font><font size="2" color="#99cc00"> </font><font size="3" color="#339966"><font size="2">- </font></font><font size="1" color="#339966">Mark Oliver Everett</font></p><p> </p> </div>
 
C

CalliArcale

Guest
It may seem weird, Enigma10, but if gravity waves exist, then this should work. (Gravity waves are mainstream science, but it is fiendishly difficult to detect them, and thus some debate remains.) This is a huge step forward, and in addition to providing new ways to probe the cosmos, it would provide further direct testing of Einstein's theories. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>
 
C

crix

Guest
I'm always a little confused when I read about some experiment being "final test of Albert Einstein's General Theory of Relativity," or in other instances "a further verification."<br /><br />I just want to point out that General Relativity is not the end. You could set up a precision experiment to verify the Newtonian mechanics of billiard balls to verify Newtons Laws of Motion, but this doesn't mean the theory is all inclusive.<br /><br />We haven't reached a final theory so there's some bigger picture theory we have yet to arrive at. I'm holding out for a another go at the Michaelson-Moreley experiement, this time though, performed in some earth trailing orbit. I read some interesting alternative physics that posits that there is an ether, but not the static, rigid one that the first MM test looked for. This other theory suggests a fluid compressible ether which interacts with matter to create a boundary layer of flow around the earth. Therefore we would need to get out into open space to get some interferrometric readings. It's an interesting idea. One that I like because I'm still not 'cool' with the idea of EM (/edit Or gravity for that matter!!) not requiring a medium to travel through... or a medium to "wave" as other have put it.
 
R

robnissen

Guest
"I read about some experiment being 'final test of Albert Einstein's General Theory of Relativity.'"<br /><br />I was about to land on you like a ton of bricks, for setting-up the obvious straw-man, that anyone would claim that any test is the "final test" of relativity. But then I read, the article. Uh . . . never mind. <br /><br />The fact is, however, that no reputable scientist would ever refer to any test as the "final test," that takes way too much hubris. Indeed, Einstein knew he was nowhere near the "final test" for relativety, because if such a "final test" could exist, it would have to unify all forces.<br /><br />Alas, journalists aren't allways as careful in their choice of words. While, contrary to what the article states, this is nowhere near the "final test," it is still a very exciting development.
 
D

derekmcd

Guest
At what point does Einstein's Theory of Relativity just become Einstein's Relativity. Detecting the arrival of gravitational waves at the same moment the light from the event arrives, would be a huge success of Relativity. It may not be the final test for the ToE, but it certainly would be one of the final experiments leading to a verification that might in turn lead to dropping "theory" from the phrase. <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>
 
C

crix

Guest
Hmm.... yeah, I suppose at some point it will be called "Einstein's Laws of Relativity."
 
B

bobw

Guest
<font color="yellow">At what point does Einstein's Theory of Relativity just become Einstein's Relativity.</font><br /><br />I doubt that will ever happen.The way I understand it a law is a simple statement about some specific thing such as F=MA or PV=NRT, usually a law can be explained by one equation. A theory is broader. I found this quotation at Scientific American. The main idea isn't to get the word "theory" removed from your idea. Far from it; finding a theory is a goal to be achieved.<br /><br /><i>"Many people learned in elementary school that a theory falls in the middle of a hierarchy of certainty--above a mere hypothesis but below a law. Scientists do not use the terms that way, however. According to the National Academy of Sciences (NAS), a scientific theory is "a well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses." No amount of validation changes a theory into a law, which is a descriptive generalization about nature. So when scientists talk about the theory of evolution--or the atomic theory or the theory of relativity, for that matter--they are not expressing reservations about its truth.</i><br /><br />My interpretation of "the last validation of Einstein's theory of relativity" is that it will detect, for the first time, the last unobserved prediction of relativity. We have seen time dilation, curved space, frame dragging, and now finally we hope to see those gravity waves. I don't think it means "this is the ultimate experiment and, at last, we will be done". <div class="Discussion_UserSignature"> </div>
 
E

earth_bound_misfit

Guest
Well I guess it goes from theory to practise <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <p> </p><p> </p><p>----------------------------------------------------------------- </p><p>Wanna see this site looking like the old SDC uplink?</p><p>Go here to see how: <strong>SDC Eye saver </strong>  </p> </div>
 
B

bobw

Guest
I have a question about GEO600. I read that "The joint German-British Gravitational Wave Detector GEO600 has now entered an 18-month run of continuous measurement." Does that mean that it is going to be 18 months before any major new upgrades or that they can actually run in science mode for 18 months? I like to read the LIGO detector logs and they are full of glitches. Have the Germans/Brits solved this type of problem? Is it easier to keep GEO600 running because it is smaller? Does anybody know where I can read details about GEO600 comparable to those of the Hanford Ligo instrument below? <br /><br />15:10:36<br />Tue Jun 27<br />2006 <br /><font color="yellow"> H2 lost lock at approx. 14:47 PT due to some seismic visible on the Rattlesnake monitor. After it reacquired, I gave it some ETM and RM tweaks to bring up arm buildups and spob before taking it back to powerup. </font><br /><br />17:52:00<br />Tue Jun 27<br />2006 <br /><font color="yellow"> H2-1349 dropped due to sitewide seismic in the 1-30Hz bands. Interestingly, the 4k stayed in lock/SM.<br /><br />Roughly at the same time as the H2 LL, LLO dropped lock due to a train.<br />They report to be down for another ~10min.<br />Because of this, Jamie is taking the opportunity to run a few minutes of 4k ISS measurements with the loop off. H1-1691 was dropped for this. </font><br /><br />22:29:46<br />Tue Jun 27<br />2006 <br /><font color="yellow">Afternoon Shift Summary<br />Not particularly great today as far as duty cycle. Quite a few lock losses in H1, probably due to the ISS glitches mostly. The wind picked up significantly in the late evening and has been causing quite a bit of trouble in the last couple of hours, both in H1 and H2. The wind has died down a bit, but expect that it might cause more trouble through the night. </font><br /><br />07:59:28<br />Wed Jun 28<br />2006 <br /><font color="yellow"> Other than some "planned" intervention, shift was fairly quiet.<br /><br />H2:<br />* #1353</font> <div class="Discussion_UserSignature"> </div>
 
R

rogers_buck

Guest
They use verry long baseline optical interferometers to detect the distortions of space-time that would indicate the passing of a gravitational wave. Given the obvious need for sensitivity and accuracy the technical challenges are daunting. But I believe the fundamental problem may well have been with processing the data. Everything from cars driving on freeways hundreds of miles away to various noise sources within the apparatus have to be decenable as a true signal. Having multiple instruments thousands of miles apart will be a real tonic.<br />
 
Y

yevaud

Guest
True. A recent document I read (sorry, I don't recollect which site it was at) was a day-to-day log of LIGO running, and it kept having glitches and problems due to low-level seismic activity, computer and electronics trouble and, in one case, a passing train. <div class="Discussion_UserSignature"> <p><em>Differential Diagnosis:  </em>"<strong><em>I am both amused and annoyed that you think I should be less stubborn than you are</em></strong>."<br /> </p> </div>
 
B

bobw

Guest
They are really great machines and I wish them all the luck too. Just reading the logs is a trip. The footpads and the mirror alignment; heck, the other day one of the operators (probably physics grad students, they sound like electrical engineers, too) tweaked one of the software calibration factors in the 6 th digit. Very cool stuff. <br /><br />They can detect the difference in the gravity field when a nearby hill gets wet from rain. They know what most of their noise is from. When they find a new source they track it down. Once they used accelerometers on the floor to triangulate something loose inside a big cryogenic tank which "popped" once in a while. <br /><br />Edit: Answered before I read the whole post.<br /><br />I guess they are trying to test for it but the idea is that accelerating mass produces gravity waves just like accelerating electrons produce radio waves. They propogate the same way and the equatiions are similar. If they expect to someday find stretched out gravity waves from the big bang that would pretty much imply that gravity waves permeate the universe, so yes, I'd say that gravity waves all the time. The problem is you have to accelerate really big masses pretty close to us to have a chance of detecting it. They will probably detect inspiraling black holes first; much like the first extrasolar planets were all hot jupiters.<br /><br />Link to electronic logs:<br />http://ilog.ligo-wa.caltech.edu/ilog/ <div class="Discussion_UserSignature"> </div>
 
B

bobw

Guest
I was just catching up on LIGO, reading some logs, and I thought it might be nice to bump this thread and post some pictures. LIGO is doing much better lately and gathering good data during stretches of well over 24 hours at a time now without dropping out of science mode. The einstein at home distributed computing project is crunching the data right now.<br /><br />Sorry if the pictures are a little blurry but they started out much larger and I had to shrink them to the 800 pixel width limit. I hope everyone enjoys a quick look at some cutting edge stuff.<br /><br />This is the overview screen from the control software that runs LIGO. The graphic representation of the interferometer is stretched along the lower (X arm) part of the screen, around the corner (main building) and up the left edge (Y arm) of the screen. If it works like SCADA (Supervisory Control And Data Acquisition) software I am familiar with then you can click on the nodes and open a new screen with just stuff about that node. All of the other information on the main overview screen, besides the diagram, is just the data that they need to keep an eye on pretty regularly. The details are in the sub screens. <div class="Discussion_UserSignature"> </div>
 
B

bobw

Guest
Here is the log from when LIGO dropped out of science mode due to a small earthquake, along with a picture of the graph from a seismometer located at the end of the "Y" arm. That would be at the circle labeled "10" at the end of the arm along the left side of the control overview screen.<br /><br /><font color="yellow">H1/H2 segments ended around 12:40pm.<br /><br />Reason: Seismic<br />Heard a helicopter around LVEA a minute later. Seismic QScan was interesting in that it showed a few different types of activity:<br />(1) ~1Hz sitewide seismic blast (lasted about a min)<br />(2) 15Hz (& harmonics??) helicopter? (lasted over 2.5min)<br />(3) 4-10Hz a truck (at EY only)<br />My guess is that the 1Hz seismic is what knocked us out (it's low in frequency & closest to our most sensitive resonances [i.e. pendulum, stack, etc.])</font>/safety_wrapper> <div class="Discussion_UserSignature"> </div>
 
B

bobw

Guest
This is the same event from the seismometer at the center of the X arm. That would be at the circle numbered "5" on the bottom arm on the diagram from the control overview screen. No truck here. I suppose by comparing both graphs the hard core data dawgs among us could make a pretty good guess about the helicopter's course and speed.<br /><br /><font color="yellow">MX Seismometer During Seismic Event<br />Here one can see the "helicopter" signature a little better (along w/ the seismic blast).</font>/safety_wrapper> <div class="Discussion_UserSignature"> </div>
 
B

bobw

Guest
The upper right graph in this picture shows the range at which LIGO could theoretically detect inspiraling white dwarf stars before and during the small earthquake. Where the range drops off is when LIGO went out of science mode. The red trace is from the 4 kilometer arms. It was humming along "seeing" about 15 megaparsecs. The blue trace is from a 2 kilometer interferometer built into the same tubes. It was "seeing" about 7 megaparsecs when the quake hit. The green lines are from Hanford's sister interferometer in Livingston. It wasn't working as well as Hanford right then. <div class="Discussion_UserSignature"> </div>
 
B

bobw

Guest
Since the big brush fire out there a few years ago they are a lot more careful about clearing out fire hazards. It seems to be a pretty big job. Whenever people or vehicles get near the arms they have to log the times and tag the data. The range on the 2 kilometer arm dropped from 7 megaparsecs to 3.5 megaparsecs while Oscar was working out there to clear the tumbleweeds. Here is a Picture of tumbleweeds from December 15 this year and some log entries to go with it. Note the tumbleweeds on top of the building by the stairs.<br /><br /><font color="yellow">Winds still blowing hard at all stations. 60 to 70+ mph gusts. Both ifos in OFF state.<br /><br />Just after Oscar did such a great job of clearing the site of tumbleweeds, last night's wind storm gave us another spattering of tumbleweeds. Most of our buildup was here at the LVEA; attached picture shows some 8-10' pines being buried as well as our elec. cars/forklift.<br /><br />December 18<br /><br />Beginning around 1325utc, the H2 Range dropped to 3.5 Mpc with an 10x rise in 1-10hz mostly, less rise in other frequencies. This appears to be Oscar baling as he neared and passed the MX. We don't seem to be too sensitive actually as the range recovered as soon as we could see him from the LVEA via the camera.<br /><br />Oscar has left the site now done for the day baling tumbleweeds. I've cleared the activity and duration.</font>/safety_wrapper> <div class="Discussion_UserSignature"> </div>
 
M

MeteorWayne

Guest
bobw,<br />Thanx Very much for this information.<br />Einstein@home doesn't do a great job in giving you a feel for what's going on, this is the most information I've ever gotten.<br />Could you PM me the original images so I can see some detail? Or send it to my e-mail. It's fascinating information, and I really appreciate it.<br /><br />Bump away! <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>
 
B

bobw

Guest
Check your PM's MeteorWayne and thanks for the encouragement. You are right about it being tough to find news. Before I hit the logs I checked the website for news releases. The latest one was from March. It may be sort of a good thing... they probably need all their bandwidth and don't have a lot of money to spend on public servers.<br /><br />One of the logs, around the end of November, told of someone who had started a collection of pictures. Many of the subdirectories are empty. I have browsed through and found some pictures though. The log warned that they are all very big files. I'm not sure if access is open or if I have a cookie on my computer somewhere from logging on to the electronic log webpage so if it asks you to log in just tell them you are "reader" and your password is "readonly". These are pictures only, no captions. Here is the root directory for the pictures.<br /><br />http://www.ligo-wa.caltech.edu/~cgray/lho_picture_library/<br /><br />And here are some of the subdirectories which I know have pictures.<br /><br />http://www.ligo-wa.caltech.edu/~cgray/lho_picture_library/ex/BSC9/<br />http://www.ligo-wa.caltech.edu/~cgray/lho_picture_library/ex/racks/<br />http://www.ligo-wa.caltech.edu/~cgray/lho_picture_library/lvea/h1/isct4/<br />http://www.ligo-wa.caltech.edu/~cgray/lho_picture_library/lvea/h1/misc/<br />http://www.ligo-wa.caltech.edu/~cgray/lho_picture_library/lvea/h1/racks/ <div class="Discussion_UserSignature"> </div>
 
B

bobw

Guest
Additionally, these instruments are a work in progress. Here is one of the latest, most interesting findings. Author: Robert Schofield<br /><br /><font color="yellow"><b>60 Hz Peak in H1 Partly from 500kV Transmission Lines</b><br /><br />The high-voltage lines that parallel the Y-arm can account for roughly 1/2 of the 60 Hz peak in the H1 gravitational wave channel. This portion of the 60 Hz peak in DARM is likely to be produced by the magnetic fields generated by the current in the high-voltage lines coupling directly to the magnets on the test masses.<br /><br />-Introduction<br /><br />A pair of 500kV transmission lines roughly parallels the LHO Y-Arm, passing about 2 km from the corner and 3 km from the Y-end station (see Fig. 1), on their way to the Slatt and Marion substations in Oregon. In a Sept. 18th elog I noted that faults and trips on these lines (as far away as Marion in central Oregon) were responsible for some of the H1 H2 coincidences that Erik, Laura and the glitch group had associated with magnetic field bursts.<br /><br />-Correlation between currents and 60 Hz peak in DARM<br /><br />Figure 2 shows that the 60 Hz peak in H1 DARM nearly doubles in amplitude as the current in the Ashe-Slatt and Ashe-Marion lines increase from about 500 Amps to about 2000 Amps. Figure 2 also shows that, unlike H1, the height of the 60 Hz peak in H2 does not appear to be correlated with the current in the high-tension lines. Although, in Figure 2, the amplitude of the 60 Hz peak in H2 is smaller than in H1, in calibrated units the peak in H2 is actually about twice as large as the 60 Hz peak in H1. It may be that 60 Hz noise from other sources was obscuring any correlation with the high-tension lines for H2.<br /><br />-Magnetic fields follow currents<br /><br />Figure 3 shows plots of the Z magnetic field at Y-end and the current in the high-tension lines. The match between features in the current and in the magnetic field suggests that the magnetic fields from the high-tension lin</font> <div class="Discussion_UserSignature"> </div>
 
Status
Not open for further replies.

Latest posts