APOD: Gravity Probe B Confirms Einstein (2011 May 10)

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APOD: Gravity Probe B Confirms Einstein (2011 May 10)

Post by APOD Robot » Tue May 10, 2011 4:48 am

Image Gravity Probe B Confirms the Existence of Gravitomagnetism

Explanation: Does gravity have a magnetic counterpart? Spin any electric charge and you get a magnetic field. Spin any mass and, according to Einstein, you should get a very slight effect that acts something like magnetism. This effect is expected to be so small that it is beyond practical experience and ground laboratory measurement. In a bold attempt to directly measure gravitomagnetism, NASA launched in 2004 the smoothest spheres ever manufactured into space to see how they spin. These four spheres, each roughly the size of a ping-pong ball, are the key to the ultra-precise gyroscopes at the core of Gravity Probe B. Last week, after accounting for persistent background signals, the results were announced -- the gyroscopes precessed at a rate consistent with the gravitational predictions of Einstein's General Theory of Relativity. The results, which bolster existing findings, may have untold long term benefits as well as shorter term benefits such as better clocks and global positioning trackers.

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Re: APOD: Gravity Probe B Confirms Einstein (2011 May 10)

Post by bystander » Tue May 10, 2011 5:10 am

Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

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Re: APOD: Gravity Probe B Confirms Einstein (2011 May 10)

Post by nescirob » Tue May 10, 2011 6:15 am

There is a mistake in the units of measure of the gravomagnetic effect. It is 39 microarcsec/year, not milliarcsec/year. By the way it should be les than the geodetic precession, as indicated by the vectors drawn in the figure.
Roberto Nesci

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Re: APOD: Gravity Probe B Confirms Einstein (2011 May 10)

Post by Redbone » Tue May 10, 2011 11:57 am

A fascinating experiment, certainly. But results like this trigger skepticism. Not in the effects predicted by general relativity, which are extremely sound, but in the conduct of the experiment. Measuring infinitesimal changes to a system at the limit of accuracy should certainly cause some concern. As with accounting bias, errors that favor the bias are often overlooked, while errors that contradict the bias are almost always caught.

“first preliminary results released in April 2007 point toward a so far obtained accuracy of[56] 256–128%, with the hope of reaching about 13% in December 2007.[57] In 2008 the Senior Review Report of the NASA Astrophysics Division Operating Missions stated that it is unlikely that Gravity Probe B team will be able to reduce the errors to the level necessary to produce a convincing test of currently-untested aspects of General Relativity (including Frame-dragging).[58][59] On May 4, 2011, the Stanford-based analysis group and NASA announced that the data from GP-B demonstrate the frame-dragging effect with an error of about 19 percent.[60] The findings were accepted for publication in the journal Physical Review Letters[61].”

So what happened between 2008 and now? That needs to be explained clearly, completely and in great detail with ample access to the data. Let some other eyes that don’t have extreme vested interests and whose careers aren’t linked to the success or failure of this project have a look at the data. We are starting to see an awful lot of marginal or just plain meaningless results being touted as significant finds simply for the sake of publication and career advancement.

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Re: APOD: Gravity Probe B Confirms Einstein (2011 May 10)

Post by neufer » Tue May 10, 2011 12:25 pm

nescirob wrote:
There is a mistake in the units of measure of the gravomagnetic effect. It is 39 microarcsec/year, not milliarcsec/year. By the way it should be les than the geodetic precession, as indicated by the vectors drawn in the figure.
No one could measure 39 microarcsec/year = 11 degrees/100,000,000 years :!:
Art Neuendorffer

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Re: APOD: Gravity Probe B Confirms Einstein (2011 May 10)

Post by snesin- » Tue May 10, 2011 3:30 pm

The links for previous page, next page and discussion are incorrect. It looks like the page was copied from May 8th, but the links not updated.

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Re: APOD: Gravity Probe B Confirms Einstein (2011 May 10)

Post by nstahl » Tue May 10, 2011 5:27 pm

I'm glad that links problem is happening to you, too. :)

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Re: APOD: Gravity Probe B Confirms Einstein (2011 May 10)

Post by geckzilla » Tue May 10, 2011 6:21 pm

The links do that from time to time. I presume an email has already been sent to RJN but I haven't seen the others mention it so I'll go ahead and do it.
Just call me "geck" because "zilla" is like a last name.

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Re: APOD: Gravity Probe B Confirms Einstein (2011 May 10)

Post by biddie67 » Wed May 11, 2011 1:19 am

This APOD with its links is an educational tour-de-force! I was slowly trying to read my way through the links but the concept of "frame-dragging" completely lost me. Obviously, my educational experiences were elsewhere - my obstinate mind kept demanding "what frame is getting dragged around?". (Don't think the article is referencing something so basic as a picture frame.)

But I'll keep trying - maybe I'll get it .....

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Re: APOD: Gravity Probe B Confirms Einstein (2011 May 10)

Post by abhagwat » Wed May 11, 2011 1:41 am

Whenever i saw images of the Sun with magnetic loops, I always thought they were gravito-magnetic loops!

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Re: APOD: Gravity Probe B Confirms Einstein (2011 May 10)

Post by moonstruck » Wed May 11, 2011 4:16 am

Thanks to the Gravity Probe B team. If the rest of the folks would appreciate what they are doing instead of trying to find fault and nitpick everything they do this world might eventually be a better place. I'll bet no one on this forum can make the the world's smoothest sphere. I clicked on that link and spent almost all day studying how that was done. That and all the technology that goes with it is simply amazing. Way to go Gravity Probe B team.

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Re: APOD: Gravity Probe B Confirms Einstein (2011 May 10)

Post by hackerspiff » Wed May 11, 2011 2:32 pm

If the rest of the folks would appreciate what they are doing instead of trying to find fault and nitpick everything they do this world might eventually be a better place.
One of the beauties of our scientific method is its inherent reliance on checks and balances.

People are naturally wishful thinkers and when they have a theory that they think is viable, they become emotionally vested in hoping that the experiment validates their work. This is a good thing in a way because it helps drive very difficult projects to completion and publication.

But scientists are naturally skeptical and competitive. This is a good thing because it drives an author's peers to try to find chinks in the reasoning of even seemingly well crafted experiments and publications. Many mistaken claims have been sniffed out and productively dismantled because peers have sought to establish their own credibility and standing through counter arguments and counter experiments conducted in the public forum of scientific discourse.

Skepticism and respectful competitive drive are necessary and vital attributes of the scientific process. These qualities actually help science thrive. I would argue that these checks and balances help make the world a better place by keeping science honest, credible, and productive!