Einstein's predicted geodetic and frame-dragging effects, and the Schiff Equation for calculating them. Credit: Stanford University

Gravity Probe B Confirms Two of Einstein’s Space-Time Theories

4 May , 2011 by

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Researchers have confirmed two predictions of Albert Einstein’s general theory of relativity, concluding one of NASA’s longest-running projects. The Gravity Probe B experiment used four ultra-precise gyroscopes housed in an Earth-orbiting satellite to measure two aspects of Einstein’s theory about gravity. The first is the geodetic effect, or the warping of space and time around a gravitational body. The second is frame-dragging, which is the amount a spinning object pulls space and time with it as it rotates.

Gravity Probe-B determined both effects with unprecedented precision by pointing at a single star, IM Pegasi, while in a polar orbit around Earth. If gravity did not affect space and time, GP-B’s gyroscopes would point in the same direction forever while in orbit. But in confirmation of Einstein’s theories, the gyroscopes experienced measurable, minute changes in the direction of their spin, while Earth’s gravity pulled at them.

The project as been in the works for 52 years.

The findings are online in the journal Physical Review Letters.

Artist concept of Gravity Probe B orbiting the Earth to measure space-time, a four-dimensional description of the universe including height, width, length, and time. Image credit: NASA

“Imagine the Earth as if it were immersed in honey,”.said Francis Everitt, Gravity Probe-B principal investigator at Stanford University. “As the planet rotates, the honey around it would swirl, and it’s the same with space and time,” “GP-B confirmed two of the most profound predictions of Einstein’s universe, having far-reaching implications across astrophysics research. Likewise, the decades of technological innovation behind the mission will have a lasting legacy on Earth and in space.”

NASA began development of this project starting in the fall of 1963 with initial funding to develop a relativity gyroscope experiment. Subsequent decades of development led to groundbreaking technologies to control environmental disturbances on spacecraft, such as aerodynamic drag, magnetic fields and thermal variations. The mission’s star tracker and gyroscopes were the most precise ever designed and produced.

GP-B completed its data collection operations and was decommissioned in December 2010.

“The mission results will have a long-term impact on the work of theoretical physicists,” said Bill Danchi, senior astrophysicist and program scientist at NASA Headquarters in Washington. “Every future challenge to Einstein’s theories of general relativity will have to seek more precise measurements than the remarkable work GP-B accomplished.”

Innovations enabled by GP-B have been used in GPS technologies that allow airplanes to land unaided. Additional GP-B technologies were applied to NASA’s Cosmic Background Explorer mission, which accurately determined the universe’s background radiation. That measurement is the underpinning of the big-bang theory, and led to the Nobel Prize for NASA physicist John Mather.

The drag-free satellite concept pioneered by GP-B made a number of Earth-observing satellites possible, including NASA’s Gravity Recovery and Climate Experiment and the European Space Agency’s Gravity field and steady-state Ocean Circulation Explorer. These satellites provide the most precise measurements of the shape of the Earth, critical for precise navigation on land and sea, and understanding the relationship between ocean circulation and climate patterns.

GP-B also advanced the frontiers of knowledge and provided a practical training ground for 100 doctoral students and 15 master’s degree candidates at universities across the United States. More than 350 undergraduates and more than four dozen high school students also worked on the project with leading scientists and aerospace engineers from industry and government. One undergraduate student who worked on GP-B became the first female astronaut in space, Sally Ride. Another was Eric Cornell who won the Nobel Prize in Physics in 2001.

“GP-B adds to the knowledge base on relativity in important ways and its positive impact will be felt in the careers of students whose educations were enriched by the project,” said Ed Weiler, associate administrator for the Science Mission Directorate at NASA Headquarters.

Sources: NASA, Stanford University

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Olaf
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Olaf
May 4, 2011 7:21 PM

First!

Lawrence B. Crowell
Member
Lawrence B. Crowell
May 4, 2011 8:19 PM

Score another mile stone for big Al, Albert Einstein.

LC

CrazyEddieBlogger
Member
May 4, 2011 9:14 PM

Proof! I want Proof.
A long-hand version of the data log of ALL the gyros please, in original paper form!

(sorry…)

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
May 5, 2011 11:50 AM

Anti-relativists will have their frame dragged into the science, relatively dissatisfied (read: kicking and screaming) all the time.

Question
Member
Question
May 4, 2011 9:45 PM

the nature of frame-dragging and its effects is a fascinating area of study. as a “geometry guy”, it makes me feel like sketching things.

Don Alexander
Member
Don Alexander
May 4, 2011 9:49 PM

This.
Is.
Fantastic.

Bill
Member
Bill
May 4, 2011 10:04 PM
WOW! I hope I can get use to this understanding I have now. I am by no means a mathematician but astrophysics fascinates me. The fascination began when I read “A Brief History of Time.” I have read many books on the same subject but could never understand all the formulas most of the authors use. When it was spelled out to me I could imagine it in my mind. They say a picture is worth a thousand words. Well the two examples shown here speak upteen thousands of words. I can see what I could only imagine, and the accompanying text put it all in a nice little nut shell for me. Now let us visualize more… Read more »
Greg
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Greg
May 5, 2011 2:46 AM
It is reassuring to see these gravity principles confirmed yet again by another method. Unfortunately this measurement of the Lense-Thirring effect (which is what is new today regarding this experiment) was scooped by Tom Murphy in 2008 by the latest Lunar Laser Ranging experiments and with much greater precision (.1 percent versus 20 percent for this experiment.) The Lageos I and II satellite experiment also scooped this mission even earlier in 2004, achieving confirmation of frame dragging with 10 percent precision, although I believe the GPB data is still being refined to weed out noise which may still yield better precision. See references below. Murphy, T.W., Adelberger,E.G., Battat, J.B.R., Carey, L.N., Hoyle, C.D., LeBlanc, P., Michelsen, E.L., Nordtvedt,… Read more »
Torbjorn Larsson OM
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Torbjorn Larsson OM
May 5, 2011 11:48 AM

Thanks for the info, I remembered vaguely that frame dragging was already tested.

1234567890
Member
1234567890
May 5, 2011 7:45 PM

Sorry, Greg, but the results by Murphy et al. do not refer to the same effect tested by GP-B and LAGEOS. About the LAGEOS tests by Ciufolini, please note that after 15 years nobody has, actually, repeated them independently of Ciufolini himself. Moreover, the 10% accuracy in it is a legend. You may want to look at this recent open access
L. Iorio, On Some Critical Issues of the LAGEOS-Based Tests of the Lense-Thirring Effect, Journal of Modern Physics, vol. 2, no. 4, pp. 210-218, 2011
http://dx.doi.org/10.4236/jmp.2011.24029 and references therein. Enjoy!

Greg
Member
Greg
May 6, 2011 12:07 AM
Very good reading indeed. This paper claims that Ciufolini’s analysis was biased by assigning fixed values to uncertain zonal harmonic values. When these uncertainties are factored in the accuracy decreases by 20 percent or more. There is a simple soultion, however, and that is having other laser range finding facilities repeat the experiment. I am puzzled why other teams have not done this yet. As it turns out all of the other papers done were done by various members of his team at his facility. This certainly sheds new light on the value of the GPB experiment. The actual effect measured by the laser range finders that scooped GPB is the gravitomagnetic effect. (conferring of rotation on a… Read more »
Torbjorn Larsson OM
Member
Torbjorn Larsson OM
May 7, 2011 12:22 PM

FTW Wikipedia do lists some earlier tests (though it may be this one and/or shaky et cetera). Anyway, the more tests the merrier!

Valentina Tereshkova
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Valentina Tereshkova
May 5, 2011 5:12 AM

“One undergraduate student who worked on GP-B became the first female astronaut in space, Sally Ride.”

So who am I? Chopped liver?

Uncle Fred
Member
Uncle Fred
May 5, 2011 10:25 PM

Lol. It’s just Americans being Americans. Sometimes I think more than an Ocean separates them from the rest of humanity.

Billy
Member
Billy
May 5, 2011 11:56 PM

You’re the first female cosmonaut in space.
Sally’s the first female astronaut in space.

smile

CrazyEddieBlogger
Member
May 5, 2011 6:09 AM

Valentina – (Whether it’s really you or not…)

Thanks for a great laugh and appreciate the sense of humor –

Respect!

scozy
Member
scozy
May 5, 2011 7:30 AM

this is facinating,
but was wondering if this research will be backed up with an other project on a bigger scale ,like jupiter. If this data is correct; would the effects not be shown on a shorter time frame?

interI0per
Member
interI0per
May 5, 2011 2:12 PM
The image of the sphere of the planet with a ‘well’ beneath the south pole is misleading. The “stress field” would project from the center of the sphere outward in an inverted ‘metasphere’ in all spherical directions. The stress decreasing with distance. The disc perpendicular to the equator (like Saturn’s ring disk) would be a projection of the maximum gravometric stress. This is caused by the maximum mass of the planet in the disc of the equator. (spin causes this) Also: I imagine space to be more like glass than honey. Does the ‘fabric of space’ possess inertia? It would seem to be massless but stressable. Would a hypothetically perfect spherical spinning mass impart coriolis to the surrounding… Read more »
Torbjorn Larsson OM
Member
Torbjorn Larsson OM
May 7, 2011 12:24 PM

Well, it is an illustration. Spacetime creates inertia, is a better way of thinking of it I believe.

Lawrence B. Crowell
Member
Lawrence B. Crowell
May 5, 2011 2:39 PM
To give some idea of the physics behind this frame dragging a couple of points or aspects of looking at it can be made. This can be thought of as a form of magnetism associated with gravity, in much the same way magnetism is associated with the electric field and charge. This means that in analogy with electromagnetism a moving mass will be associated with a gravity analogue of a magnetic field. This means that a rotating mass will have a field similar to a magnetic field associated with a spinning charge. As a result the magnetic field for a spinning charge may be computed by the Faraday equation so that curl H = J, which if we… Read more »
interI0per
Member
interI0per
May 5, 2011 7:15 PM

HA! I was thinking the same thing as soon as i posted. (Perhaps it’s better to think of space with less viscosity than honey and not more (glass). Both space and the gravity that acts upon it must be abstracted in the mind to be contemplated. How best to do so?
The magnetic field analogy is inaccurate in my mind (but close) for 2 reasons.
I imagine gravity to be unipolar and static.
Gravity would not emanate looping field lines but more of a gradually decreasing stress field around the mass in space.
I think it’s utterly charge agnostic and the result of aggregations of neutrons.

Andrew James
Member
May 5, 2011 3:47 PM
“Imagine the Earth as if it were immersed in honey…” Good analogy, but honey is thixotropic and a sheer-thinning liquid, and whose viscosity thins when stressed through mixing. It is a non-Newtonian fluid, actually. Such fluids would not be analogous to frame-dragging precession. (Probably fairly esoteric point, but an important point.) Honey has a viscosity of about (&eta 10 pa.s. (Pascals per second.) Less viscous materials are ordinarily in mPa.s (millipascals per second.) [American’s (I think) do not use to pascals use the term poise, being dyne second per square centimeter [dyne s/cm^2].] Lawrence’s text above seems similar to fluid dynamic viscosities, with the term “-GM/r^2” being equivalent shearing stress (Force / Accleration). The other term here is… Read more »
Lawrence B. Crowell
Member
Lawrence B. Crowell
May 5, 2011 10:47 PM

Strominger and his group have illustrated how the type I Petrov solutions to the Einstein field equations are equivalent to a set of solutions to the Navier-Stokes equation.

http://arxiv.org/abs/1104.5502

So the comparison between the structure of spacetime and hydrodynamics is fairly tight. The evolution of a spatial surface involves the flow of points on that manifold. It turns out that for a certain class of such solutions these are indeed isomorphic to a class of solutions to the Navier Stokes equations.

LC

forrest noble
Member
May 6, 2011 2:48 AM
The original purpose of the gravity B probe was to generally “prove” Einstein’s theory of General Relativity, After a great effort which involved high-cost funding and many years preparation which included many scientists and computations, the observations did not find that the calculations of General Relativity fit within the acceptable tolerances predetermined beforehand as necessary for proof of theory. Based upon results that did not fall within these predetermined tolerances, congress finally pulled the plug on this project funding in 2008.. To get the best data outcome possible and to salvage some value from the monumental costs and efforts, private funding was solicited to enable the finish of the project. The Saudi royal family paid for the last… Read more »
Andrew James
Member
May 6, 2011 4:47 AM
“the observations did not find that the calculations of General Relativity fit within the acceptable tolerances & ” “….no other model seemed to predict things any better.” Let’s see General Relativity (off the top of my head….) – Gravity Probe A, 1976. Fly an atomic hydrogen maser on a Scout rocket launched to a height of 10,000 km. A maser is like a laser for microwaves. It produces microwaves of a very precise frequency. Measure the doppler shift due to gravity and motion and compare to predicted values (error = 70 ppm = 0.007%). – Confirmed in an experiment conducted in an elevator shaft at Harvard University by Robert Pound and Glen Rebka in 1959. – Clocks on… Read more »
Andrew James
Member
May 6, 2011 4:59 AM

Hey, that is simply wacko!. Only a crazy person could say something as foolish as to what you’ve written above. What is clearly conclusive about this effect was that is was written about before it was discovered.
I do strongly suggest you change your avatar name from forrest noble to forrest gump!

forrest noble
Member
May 6, 2011 5:27 AM

According to the link that I posted above their accuracy/ error concerning frame dragging was within 19%, the stated goal was to be accurate within 1%. The geodetic effect was accurate to within .2% which reconfirmed prior findings of other studies.

Those conducting the experiment/ probe believed the frame dragging variation between observation and theory were due to design and manufacturing errors of the probe rather than with the predictions of General Relativity.

Below is a discussion of other gravity and torsion theories that were originally submitted for evaluation concerning gravity probe B’s data.

http://prd.aps.org/abstract/PRD/v75/i12/e124016

Andrew James
Member
May 6, 2011 6:47 AM
General Relativity has not been rejected by science because it has both good mathematical proof and excellent observational proof. The so-called Einstein–Cartan theory (what you are actually on about here), uses the idea of (affine) torsion. It is quite well-known to be a failed attempt to extend the geometric approach of general relativity to other areas of physics. Although Cartan proposed it in 1922, Einstein spent most of the last third of his career on theories that include torsion and he did not obtain any substantial result. Effects of torsion are, frankly, too small to measure empirically at this time. They (torsion theories) are rejected, because the effects are many times smaller in magnitude that what general relativity… Read more »
Andrew James
Member
May 6, 2011 8:53 AM
Let us see; be nice and polite…. According to your own Pan Theory (and downloadable document) [linked through name here], you say; “Since General Relativity was unable to predict galactic stellar motions,” and “The fifth and most important characteristic of galaxies which is displayed by their stellar orbital speeds is the failure of General Relativity to predict stellar motion unless dark matter is progressively distributed from the outside of a galaxy inward, reminiscent of Ptolemy’s epicycles.” What? I don’t get it. Are stars moving a relativistic around the Milky Way? What have Ptolemy’s epicycles have to do with dark matter OR General Relativity? You say (pg. 57E1.1) ; “General Relativity equations have been shown to be quite accurate… Read more »
Torbjorn Larsson OM
Member
Torbjorn Larsson OM
May 7, 2011 12:36 PM
“Since General Relativity was unable to predict galactic stellar motions,” and “The fifth and most important characteristic of galaxies which is displayed by their stellar orbital speeds is the failure of General Relativity to predict stellar motion unless dark matter is progressively distributed from the outside of a galaxy inward, reminiscent of Ptolemy’s epicycles.” What? I don’t get it. Are stars moving a relativistic around the Milky Way? What have Ptolemy’s epicycles have to do with dark matter OR General Relativity? If I may… This is a folk science idea of “inductionism” as a valid theory of science as opposed to testing. It is a 19th century idea, I believe, rejected later but shored up by being a… Read more »
Torbjorn Larsson OM
Member
Torbjorn Larsson OM
May 7, 2011 12:39 PM

Oops, too brief.

What I mean is that the ref to epicycles is the mistake of saying that no theory is rejected since “one can save it by adding or modifying hypotheses”.

Never mind that the original theory _was_ rejected, and we are now engaging with a new, hopefully improved, one.

Andrew James
Member
May 7, 2011 1:04 PM

Thanks. I’ve just added this to my mental database.
(I still don’t understand the motive here of Mr. Noble. It is kind of weird. Since he does not seem to want to elaborate. Perhaps he can’t.)

Andrew James
Member
May 6, 2011 9:26 AM
Oh. I also should have said… In Wikipedia they say the following about Orbital decay under general relativity “According to general relativity, a binary system will emit gravitational waves, thereby losing energy. Due to this loss, the distance between the two orbiting bodies decreases, and so does their orbital period. Within the solar system or for ordinary double stars, the effect is too small to be observable.” [Gee. Wish I said that! I agree with this by the way…] Again this is just Newtonian orbital motion with the loss of angular momentum. Whilst it is true general relativity explains the apsidal (movement/ precession of the orbit nodes); in the majority of orbital systems general relativity / your pan… Read more »
Lawrence B. Crowell
Member
Lawrence B. Crowell
May 6, 2011 12:11 PM
The orbital decay of PSR1913+16 measured by Hulst and Taylor is an indirect indicator of gravity waves. As yet the direct detection of gravitational radiation has yet to be done. When ever I hear somebody say, “I have a theory,” my hair stands up a little bit. When it becomes clear that person has no substantial knowledge of physics I start looking for an escape or exit from the situation. Few physicsists spend endless years trying to work up some sort of conjecture they concoct as a “theory.” It takes little study to see how PAN theory being promoted by F. Noble is a load of nonsense. The problem of course is that this stuff emerges faster than… Read more »
Lawrence B. Crowell
Member
Lawrence B. Crowell
May 6, 2011 4:33 PM
I have somewhat jaded opinions of popularizations of physics. Hawking, Davies, Kaku, and now Carroll have written them, and to be honest I think many people put down these books with wrong ideas about things. My brother, a molecular biologist, read Hawking’s Brief History of Time and ended up getting in his head a strange variation on the “theme” that was not entirely correct. Some people seem to step further and get some idea of how they have a solution to the problems these books may pose, which usually ends up with some errant idea that established physics is completely wrong. So these guys get some idea that E = mc, or E = mc^3 or… , and… Read more »
Andrew James
Member
May 6, 2011 2:07 PM
I do kind of agree with you. The problem with this “theory” is that it has been hatched from something that this individual has read or misconstrued to be warped into some mishmash of ideas. I did read a lot of this document, not because I was particularly interested but I was looking for clues of the origin thence his distortion. Simply the guy seems to have completely wrong notions about relativity (This too applies to his notions of quantum mechanics, where he amazingly claims that his Pan Theory explains quantum mechanics , by his “paper” mention little about it (except pg.82). I.e. claiming “Quantum Theory, as apposed to Quantum Mechanics, is the underlying theory which tries to… Read more »
Ivan3man_At_Large
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Ivan3man_At_Large
May 6, 2011 8:04 PM

The problem of course is that this stuff emerges faster than it can be debunked.

Yeah, it’s the same with shaving: if you don’t shave regularly, you end up looking like a bum!

Torbjorn Larsson OM
Member
Torbjorn Larsson OM
May 8, 2011 8:24 PM

Ditto on the popularizations. They do let people speculate a bit over the boundary of what we have observations to match. Nothing wrong in that, except that they don’t realize it _is_ speculation.

Andrew James
Member
May 6, 2011 5:59 AM

I believe it will eventually be realized that both the Big Bang model and General Relativity are perfectly correct theory. That’s why Inflation is needed, dark matter, dark energy, general cosmology, etc. The answer I believe we already know is profoundly simple, as are our current theories. Ideas like the Pan Theory is simply incorrect theory because they are too contrived to be true.

Lawrence B. Crowell
Member
Lawrence B. Crowell
May 6, 2011 12:01 PM
@ Forest Noble: Nothing proves general relativity, for the reason that science is not about proving theories. Theories make predictions about what is observed in nature and if measurements and observations substantiate these predictions the theory is supported. This does not prove a theory to be true in a mathematical sense. Theories can be proven to be false. Observations or measurements of something other than what the theory predicts falsified that theory. Even if that theory is supported by a vast body of prior evidence, this will indicate how the theory fails outside some domain of observation. This happened to Newtonian mechanics, where it fails when the domain of experience is very small near the atomic scale or… Read more »
forrest noble
Member
May 6, 2011 3:49 PM

@Lawrence B. Crowell,

You are correct concerning “proof of theory.” This is an expression that probably should not be used.

As far as gravity waves are concerned, I do not understand why they are needed for General Relativity or the BB model since according to nearly all interpretations of GR matter “warps space” surrounding it which as I understand it is the reason for gravity so I do not understand why gravity waves are needed for either model? — or even why it is thought by many to be a prediction of the theory.

wpDiscuz