Did the Frame-Dragging Experiment Validate the Theory of Relativity?

[LaPalida]

I heard that some kind of experiment on frame-dragging was in process (or is that finished?). What was the outcome? Was the theory of Relativity vindicated? Does anyone know... wiki isn't very clear on this and it's full of math I can't even begin to imagine to understand... oh yeah also apparently wiki needs someone with expertise to improve that page (as a lay person I had a lot of trouble understanding what the heck was going on).

Oh yeah and here is the link just in case anyone wants to fix it up http://en.wikipedia.org/wiki/Frame_dragging

PS. Sorry if I posted in the wrong forum... I think I did :S

 

[pervect]

I gather from some discussion pages that those "needs attention by an expert" remarks are mainly Chris Hillman's "Things to do" list.

[add]
See for instance

http://en.wikipedia.org/wiki/User:Hillman/Wikiproject_GTR_draft
http://en.wikipedia.org/wiki/User:Hillman/WikiProject_GTR/Tasks There probably is a need for a less technical but still accurate page to describe frame dragging. I would suggest that you utilize the wiki "talk page" to address your concerns, I'm sure that there are a lot of people in a similar boat. CH is certianly doing something valuable by trying to provide graduate level input into the Wikipedia pages. There is not currently anyone I'm aware of who is "looking out" for readers without a graduate level degree.

Anway, there is an experiment that has been done on Frame dragging, it is known as "Gravity probe B".

The data has all been taken, however the results have not yet been published.

You might find

http://einstein.stanford.edu/

helpful. The main page is a discussion of the status of the experiment, but they also have some explanations of how the experiment works and what it is trying to measure.

On the extreme high end of the comprehnsibility scale (and the extreme low end of the technical accuracy scale) for frame dragging there is:

http://einstein.stanford.edu/content/education/EducatorsGuide/Page28.html

To give a rough idea, here is a quote from the page as to what's needed to carry out the proposed activity:

Setup: Each group needs a paper plate, honey, a superball, and 3-4 peppercorns.

 

[clj4]

I heard that some kind of experiment on frame-dragging was in process (or is that finished?). What was the outcome? Was the theory of Relativity vindicated? Does anyone know... wiki isn't very clear on this and it's full of math I can't even begin to imagine to understand... oh yeah also apparently wiki needs someone with expertise to improve that page (as a lay person I had a lot of trouble understanding what the heck was going on).

Oh yeah and here is the link just in case anyone wants to fix it up http://en.wikipedia.org/wiki/Frame_dragging

PS. Sorry if I posted in the wrong forum... I think I did :S

We are awaiting the results of the experiments conducted by Gravity Probe-B. The results will take another year or so in terms of getting digested and published.

 

[meemoe_uk]

The results will take another year or so in terms of getting digested and published.

Which was dissapointing to me.
With their understanding of the experiment, the researchers could have easily said whether the incoming results were in agreement with GR. This was a year ago. They just insist on sticking to tradition. I remember some comment on their site defending this conservative stance at the time.

 

[Garth]

Which was dissapointing to me.
With their understanding of the experiment, the researchers could have easily said whether the incoming results were in agreement with GR. This was a year ago. They just insist on sticking to tradition. I remember some comment on their site defending this conservative stance at the time.

As one with a vested interest in the result, who is seeking a non-"traditional" (i.e. non-GR) result on the geodetic N-S precession measurement, I take exception to your insinuation. You might be interested in the thread Alternative theories being tested by Gravity Probe B.

It may be frustrating to have to wait so long, but the experiment was very complicated with many different factors that might affect the result being assessed as accurately as possible to make that result as precise as possible. I am sure the accuracy and unambiguity thus obtained will make the wait worthwhile.

From the GP-B website

Our main focus is analyzing the science data we have collected and finishing our final report to NASA. In this regard, our final report to NASA, which is over 450 pages long, is now in the final stages of completion. Our science data analysis is proceeding according to plan. We are in the process of analyzing approximately 1 terabyte (1,000 gigabytes) of data collected from the spacecraft . Two independent analysis teams here at GP-B are working on the data, frequently comparing their results for both quality control and to ensure the validity of the data analysis algorithms.

The main part of the data analysis is expected to be completed late this summer (July-August 2006). At this point, the Harvard-Smithsonian Center for Astrophysics (CfA) will provide our science team with their ultra-precise measurements of the proper motion of the guide star, IM Pegasi. In the final step of the analysis, our science team will combine the gyroscope results with the CfA proper motion measurements of IM Pegasi to arrive at the final experimental results. These results will then be carefully and critically reviewed by international experts in general relativity and data analysis to ensure that our statement of the effects observed are as accurate as possible. Only after this review is complete--early in 2007--will we make a formal and public announcement about the results of this unprecedented test of General Relativity.

April 2007 should do it.

Garth

 

[LaPalida]

Thanks for your replies guys :)... can't wait till 2007

 

[MeJennifer]

With regards to the Wiki article there is a section about velocity frame dragging:

Velocity frame dragging is even less well known and much more controversial. Its effects (or similar effects) do seem to appear in general relativity, but it is not usually listed as a "valid" example of frame-dragging. The reasons for this are complicated.

No references are given.

What is velocity frame dragging?

 

[pervect]

I am not positive, but I would suspect that the author is talking about the apparent rotation of the fixed stars when something massive "whizzes by" them at a large velocity - or, alternatively, the same rotation as observed by someone quickly flying past a large mass.

Basically, if you fix a telescope on a guide star, and a massive body "whizzes by", after the body passses the telescope won't be pointing at the guide star anymore, it will have rotated - even if care is taken to design the telescope such that there are no tidal torques on it.

This is true even if the telescope has no angular momentum.

I ran across this effect while working on another problem. I'm not sure what the literature has to say about it, unfortunately - it's not clear what to search for, even if I had better access to the literature.

The most controversial thing I can think of offhand is that one might argue that the effect as described could be predicted from SR by treating gravity as a force as a result of Thomas precession.

The effect is rather similar to the geodetic or "De-sitter' precession that one gets in an orbit around a non-spinning test body. (Google for more info - there are a lot of hits. My statements are based on

http://en.wikipedia.org/wiki/Frame_...agihara_observers_in_the_Schwarzschild_vacuum

which may not be the easiest thing to understand).

The major difference is that the orbit in this case is not circular, it is a "flyby" orbit.

Geodetic precession is one of the things that is going to be measured by gravity probe B. It is somewhat interesting in its own right, but perhaps not as interesting as the Lense-Thiring precession, which is due to the actual rotation of the Earth, and the gravitomagnetic field caused by that rotation.

Note that the reason GP-B is in a polar orbit is so that the geodetic precession effects will occur at right angles to the Lense-Thirring precession.