The Gravity Probe B satellite has placed four (over redundant) gyroscopes in low polar Earth orbit to primarily test two predictions of General Relativity.
The first effect being tested is (for the GP-B polar orbit) a N-S geodetic precession, caused by the amount a gyro 'leans' over into the slope of curved space.
The second effect being tested is the E-W frame-dragging, Lense-Thirring, or gravitomagnetic effect, caused by the spinning Earth dragging space-time around with it.
Some researchers, such as Kenneth Nordtvedt, have said that the experiment was worth doing when it was first proposed but that now GR has been verified beyond resonable doubt the result of GP-B is a foregone conclusion.
I have now discovered several theories competing with General Relativity(GR) that are being tested and falsified by this experiment:
my Self Creation Cosmology
Moffat's Nonsymmetric Gravitational Theory
Hai-Long Zhao's mass variance SR theory
Stanley Robertson's Newtonian Gravity theory
Junhao & Xiang's Flat space-time theory
As the results will be published in the not too
distant future they could be interesting!!
(Note if anybody knows of any other theories with alternative predictions for GP-B please post them as well for comparison.)
1. GPB Geodetic precession
GR = 6.6144 arcsec/yr
SCC = 4.4096 arcsec/yr
NGT = 6.6144 - a small [itex]\sigma[/itex] correction arcsec/yr
MVSR = 6.6144 arcsec/yr
NG = 1.6536 arcsec/yr
FST = 4.4096 arcsec/yr
2. GPB gravitomagnetic frame dragging precession
GR = 0.0409 arcsec/yr
SCC = 0.0409 arcsec/yr
NGT = 0.0409 arcsec/yr
MVSR = 0.0102 arcsec/yr
NG = 0.0102 arcsec/yr
FST = 0.0000 arcsec/yr
I cannot vouch for these other theories, they may well be considered 'crackpot' by some, however all these theories have the advantage, together with GR
, that they are able to be falsified by the GP-B results.
We continue to wait and see!