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neutrino
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Now, we have to wait for a year to see if Einstein scores once again!
http://www.universetoday.com/am/publish/gravity_probe_b_finished.html
http://www.universetoday.com/am/publish/gravity_probe_b_finished.html
Maybe not - we will have to wait and see.Chronos said:I suspect the good ship GPB will spring some tantalizing leaks in the less distant future.
Garth, When you say "if GR is correct" do you mean "if Schwarzschild's solution to Einstein's field equations is correct"? Does SCC differ from GR in the field equations, the line element, or both?Garth said:Over the course of a year, if GR is correct, an angle of 6.6 arcseconds (or 5.5 arcseconds if SCC is correct) should have opened up in the N-S plane of the spacecraft ’s polar orbit, (geodetic effect), and an angle of 0.041 arcseconds (both in GR and SCC) should have opened up in the E-W direction of Earth’s rotation (Lense-Thirring effect).
Hi Aether!Aether said:Garth, When you say "if GR is correct" do you mean "if Schwarzschild's solution to Einstein's field equations is correct"? Does SCC differ from GR in the field equations, the line element, or both?
The Schwarzschild solution assumes that the spacetime surrounding a spherically symmetric gravitational field (of the Earth in this case) is empty, and that implies that the field is static. This is obviously not the case, but I'm not sure that the Gravity Probe-B experiment is sensitive enough to be affected by the difference. Were these assumptions of a static gravitational field embedded in empty spacetime used in calculating the geodetic effects for GR and SCC that you gave? Can you show both calculations, or provide a link if you have already done this somewhere else?
Because the universe is expanding/accelerating (e.g. the FLRW line element is not static). I used GRTensorII to calculate the Ricci tensor for a non-static cross between the FLRW and Schwarzschild line elements yesterday for example, and saw some new terms in there where [tex]\alpha[/tex] and [tex]\beta[/tex] are mixed up with the Hubble constant. Those terms are probably very small, but they aren't zero.Garth said:Why do you say the field is not static?
I will take a look at this paper.Garth said:I must be careful in answering your question, I do not want to be accused of "peddling my own theory" and if you want to read it up, the latest published work is here. The SCC values PPN are: [tex]\alpha=1, \beta=1[/tex] and [tex]\gamma=1/3[/tex] but the value of G is 3/2 GNewtonian.
That's very interesting - the question is:"If space is expanding what expands with it?"Aether said:Because the universe is expanding/accelerating (e.g. the FLRW line element is not static). I used GRTensorII to calculate the Ricci tensor for a non-static cross between the FLRW and Schwarzschild line elements yesterday for example, and saw some new terms in there where [tex]\alpha[/tex] and [tex]\beta[/tex] are mixed up with the Hubble constant. Those terms are probably very small, but they aren't zero.
I will be glad to answer any questions and welcome constructive criticism.I will take a look at this paper.
The purpose of Gravity Probe-B's mission was to test two aspects of Albert Einstein's theory of general relativity: the geodetic effect and frame-dragging. These theories explain how massive objects, like planets, can warp the fabric of space-time.
Gravity Probe-B's mission lasted for over 16 years. It was launched in 2004 and completed its data collection in 2010, but the analysis of the data and final results were not published until 2020.
Gravity Probe-B used gyroscopes to measure tiny changes in the direction of spin caused by the Earth's gravitational field and its rotation. These changes were then compared to predictions based on Einstein's theory of general relativity.
Gravity Probe-B's results confirmed Einstein's theories of general relativity with unprecedented accuracy. The geodetic effect and frame-dragging were measured to be within 0.28% and 19% of the predicted values, respectively.
Gravity Probe-B's mission provided strong evidence for the accuracy of Einstein's theory of general relativity, which is the foundation for our current understanding of gravity. It also demonstrated the feasibility of using gyroscopes to test fundamental aspects of physics in space.