Stanford’s Gravity Probe B confirms two Einstein theories
After 52 years of conceiving, testing and waiting, marked by scientific advances and disappointments, one of Stanford’s and NASA’s longest-running projects comes to a close with a greater understanding of the universe.
Stanford and NASA researchers have confirmed two predictions of Albert Einstein’s general theory of relativity, concluding one of the space agency’s longest-running projects.
Known as Gravity Probe B, the experiment used four ultra-precise gyroscopes housed in a 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.
After 52 years of conceiving, building, testing and waiting, the science satellite has 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, Gravity Probe B’s gyroscopes would point in the same direction forever while in orbit. But in confirmation of Einstein’s general theory of relativity, the gyroscopes experienced measurable, minute changes in the direction of their spin as they were pulled by Earth’s gravity.
The findings appear online in the journal Physical Review Letters.
“Imagine the Earth as if it were immersed in honey. As the planet rotated its axis and orbited the Sun, the honey around it would warp and swirl, and it’s the same with space and time,” said Francis Everitt, a Stanford physicist and principal investigator for Gravity Probe B.
A lasting legacy
“GP-B confirmed two of the most profound predictions of Einstein’s universe, having far-reaching implications across astrophysics research,” Everitt said. “Likewise, the decades of technological innovation behind the mission will have a lasting legacy on Earth and in space.”
Stanford has been NASA’s prime contractor for the mission and was responsible for the design and integration of the science instrument and for mission operations and data analysis.
Much of the technology needed to test Einstein’s theory had not yet been invented in 1959 when Leonard Schiff, head of Stanford’s physics department, and George E. Pugh of the Defense Department independently proposed to observe the precession of a gyroscope in an Earth-orbiting satellite with respect to a distant star. Toward that end, Schiff teamed up with Stanford colleagues William Fairbank and Robert Cannon and subsequently, in 1962, recruited Everitt.
NASA came on board in 1963 with the initial funding to develop a relativity gyroscope experiment. Forty-one years later, the satellite was launched into orbit about 400 miles above Earth.
The project was soon beset by problems and disappointment when an unexpected wobble in the gyroscopes changed their orientation and interfered with the data. It took years for a team of scientists to sift through the muddy data and salvage the information they needed.
Despite the setback, Gravity Probe B’s 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.
Played a role in developing GPS
Innovations enabled by GP-B have been used in the Global Positioning System, such as carrier-phase differential GPS, with its precision positioning that can allow an airplane to land unaided. Additional GP-B technologies were applied to NASA’s Cosmic Background Explorer mission, which determined the universe’s background radiation. That measurement is the underpinning of the “big bang theory” and led to the Nobel Prize for NASA’s John Mather.
“The mission results will have a long-term impact on the work of theoretical physicists for years to come,” 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.”
Over the course of its mission, GP-B 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. Over 350 undergraduates and more than four dozen high school students also worked on the project, alongside leading scientists and aerospace engineers from industry and government.
Sally Ride, the first American female astronaut in space, worked on GP-B while studying at Stanford. Another was Nobel Laureate Eric Cornell, who also studied at Stanford.
NASA’s Marshall Space Flight Center in Huntsville, Ala., managed the Gravity Probe-B program for the agency. Lockheed Martin Corporation of Huntsville designed, integrated and tested the space vehicle and some of its major payload components.
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Learn a lot more on testing Einstein’s theories here h/t Dr. Leif Svalgaard via email
Leif Svalgaard wrote on May 5, 2011 at 5:20 pm:
Louis Savain says:
May 5, 2011 at 3:51 pm
and time cannot change by definition.
So, what is the definition of time? And whose definition?
I’ll give you an answer but first you must apologize for calling me stupid above. Then, maybe, I’ll apologize for calling you uneducated. Until then, seeing that you have the support of the blog’s current moderator, I’ll refrain from commenting any further.
Here is an explanation of the universe’s size. [Avoid the comments unless you want to go nucking futz.☺]
Louis Savain says:
May 5, 2011 at 8:11 pm
I’ll give you an answer but first you must apologize for calling me stupid above. Then, maybe, I’ll apologize for calling you uneducated. Until then, seeing that you have the support of the blog’s current moderator, I’ll refrain from commenting any further.
Sure, Paris is worth a mass.
Leif Svalgaard says:
May 5, 2011 at 6:20 pm
Smokey says:
May 5, 2011 at 6:41 pm
===============
Thanks for the info guys.
A thought; can we tell which direction the “big bang” started from, by the red shifts of our vision?
Leif,
Thanks for all your great replies and explanations. I learned a lot as usual, and your patience with certain individuals is commendable.
Vuk etc. says:
May 5, 2011 at 5:02 am
Was Einstein the true author of ‘Einstein’ theories?>>>
I won’t give the comment further airing by quoting it. But I will call it drivel. Einstein didn’t nearly flunk math, his school changed their grading system at one point and if you don’t know that it looks like he dropped from top of class to bottom. In fact he was top of class through out. As for attempting to slag him over time frames of publication and his divorce, give me a break. If you are arguing that he produced nothing significant after divorcing his wife, so then the work must have been done by his wife… then one can only wonder why SHE produced nothing of significance after the divorce. If you want to spin the story to new heights of silliness, I suppose you could argue that it was a “man’s world” and so she couldn’t get published without her husband as a proxy. Oddly, if she had anything additional to add that she wouldn’t find another physicist to make famous? Or go have a chat with his great detractor Milliken who designed a ten year long experiment to disprove Einstein, only to prove him right?
I guess in addition to the gene that causes some humans to spew nonsense in order to discredit actual science, there must also be a gene that causes some humans to try and drag greatness into the same mud they reside in.
I find the bending of “space-time” as shown in the picture difficult to visualise,I would need to see something moving before I could tell if it was following a curved path through space.The path that objects take through space near massive bodies is bent I can visualise that,light is also bent by gravity which enables me to visualise the slowing of time.I have always had a problem with this in understanding einstein.
Sorry, I cannot join the collective worship of Dr. Leif Svalgaard (no matter how actively this ritual is encouraged by moderators).
In many cases, Dr. Svalgaard doesn’t give meaningful answers or explanations. Actual intellectual content of his posts, if you look beyond the obfuscating jargon and painful reiterations of the obvious, is difficult to discern.
Dr. Svalgaard repeats textbook definitions and/or gives you a link to a Wikipedia article that contains a textbook definition — or, if you insist on clarification, pretends to misunderstand your question (while totally lacking a normal sense of humor — recall how he repeatedly failed to recognize an obvious sarcasm).
Earlier, I asked a question: “So, the flow of time depends on the presence or absence of a large mass in vicinity. Why this is never taken into account when they talk about red shift?”
Dr. Svalgaard answered: “It is.” And, in support of his learned opinion, he directed me to the Wikipedia article on gravitational red shift effect.
Unfortunately, the article that he recommended as an answer doesn’t contain a single word about how, exactly, the gravitational red shift is being taken into account by the proponents of the Big Bang dogma. This was a regular non-answer from Dr. Svalgaard, just a waste of words and time, spiced up by unwarranted condescension and inflated self-esteem.
Whatever Dr. Svalgaard tells you, take it with a pound of salt. Recent discovery of the super-massive cluster of galaxies on the edge of the IR-visible Universe makes abundantly clear that the Big Bang hypothesis is fundamentally flawed. And yet, Dr. Svalgaard continues to lecture us in the same manner, as if his BBT dogma is as immovable as the space-time itself.
I am sick and tired of Dr. Svalgaard. Without him, this site is like a gulp of fresh air. With him, it is not.
Leif Svalgaard wrote:
Sure, Paris is worth a mass.
Certainly. However, I no longer feel that continuing this discussion is worth it to me. I have no desire to convince you of anything and I need neither your blessing nor your approval. See you around. It’s been fun.
Don’t mean to break in on the Einstein story, but having read this, I thought I would head over to New Scientist and see what they had to say, and instead found this:
Strange Cosmic Ray Hotspots Stalk Southern Skies
They mention:
Now my math isn’t my strong suit, but wouldn’t 0.03 lightyears put that near the Heliosheath ?
Plus, if I could add anything to this story about space time, wouldn’t it be better to view the space time anomaly surrounding Earth as homogeneously spatial, rather than linear?
Todays xkcd seems on topic: http://xkcd.com/
“The four gyroscopes in GP-B are the most perfect spheres ever made by humans. These ping pong-sized balls of fused quartz and silicon are 1.5 inches across and never vary from a perfect sphere by more than 40 atomic layers. If the gyroscopes weren’t so spherical, their spin axes would wobble even without the effects of relativity.”
Except they did wobble, and it took 5 years to pick “a fantastic precision of 0.0005 arcseconds” out of the data.
And here is the claim: “Every future challenge to Einstein’s theories of general relativity will have to seek more precise measurements than the remarkable work GP-B accomplished.”
“Measurements” is not the best term for this process that was undertaken to make 86 new PhDs and confirm Einstein’s GR. The words they need are “massaging” and “modeling.” IEEE Spectrum:
“The project was on very shaky ground, because even after years of data massaging, GP-B had weakly confirmed one of the effects, frame dragging, to only the 25 to 33 percent range. But as Everitt and GP-B spokesman Bob Kahn, of Stanford, told IEEE Spectrum via e-mail, a recent breakthrough in the modeling of behavior of the satellite’s instruments has increased the data’s accuracy ”by a factor of 5 to 10”.”
Zeke the Sneak;
“Measurements” is not the best term for this process that was undertaken to make 86 new PhDs and confirm Einstein’s GR. The words they need are “massaging” and “modeling.” IEEE Spectrum:….>>>>
Let’s not confuse the journey with the destination. If I say that I drove to New York, showing that I spend the first two days of the trip going the wrong way doesn’t mean I didn’t get there. They published their results and my understanding is that they showed how they calculated the wobble in order to isolate the data. If there’s something wrong with how they did it, then attack that and show how it is wrong. Citing an early attempt that was later improved upon means nothing in terms of evaluating the final technique.
Its interesting to see explanations such as “gravity warps the space around a mass”
I always understood it that its the mass that warps the space. Gravity is just the effect that results from that warping – its not the cause of the warping. Any body else ?
Leif says re my “I can’t follow your explanation on four dimensions because the base is not logical in three dimension”:
Again, does not make sense to me. Spacetime is warped in four dimension.
So you say. I have yet to see any proof that it exists, notwithstanding the title claim to proof here. All that this experiment shows is that the Earth’s spin is having some effect on the space around it, which is a ‘thing’; a thing like honey, a thing like ether, a thing like plasma. Whatever. It does not show that there is such a thing as spacetime. That’s still an assumption.
Re my “Can’t you just answer my three dimension problem? If there is something called space (or space/time) in which a body impinges warping it, then it must be impinging on it equally with all its mass in every direction, which cancels all the impinging out”:
And why would that be? And spacetime does not have three dimensions, so why are you hung up on a ‘three-dimensional problem’?
Because it is a three dimensional problem in a three dimensional universe. For a moment, for our discussion, bear in mind that space/time is an assumption, it is simply space in our universe and all that experiment has shown is that space is not empty of stuff. All you are doing is calling this stuff, space/time.
Your claim is that space/time is four dimensions is irrelevant to the three dimensional problem this actually is, and into which relativity itself puts it, it is ‘stuff’ surrounding the Earth in which the Earth impinges in a three dimensional way, by its mass warping it.
So, whether we call it space or ether or space/time or honey or plasma or thin air makes no difference, it is something in which another body moves, like throwing a ball into a lake, it is still a three dimensional problem. Let’s call it stuff. This stuff you say is being warped by Earth’s mass which then creates gravity.
OK. The mass warping stuff around it can only be doing so in one direction to produce the effect of gravity claimed this warping produces. If the mass of Earth is warping the stuff around it, it must be doing it in all directions. Which means that all the directions cancel each other out and there is effectively no warp, because an object approaching it will be ‘passed’ from one warp point to the next.
What we’re looking at in analogy is the mass of the Earth warping the inside of a balloon by its mass, from the inside.
If the mass of the Earth is warping the space around it, the whole of the inside of the balloon, then it is doing so ‘equally’ at every point which cancels out the warps. ‘Equally’ like ‘average’, it could be that the Earth is heavier weighted at some point so its interacting with whatever stuff it’s in is to a greater or lesser amount than ‘equal’.
A massless photon coming towards a massive body from a given direction will deviate from the usual Newtonian straight line and seem to follow a curved [warped] trajectory. This is observed everywhere around the the mass and shows that the space is warped everywhere. The warping only depending on the distance from the mass.
But as before, you’re still presenting a three dimensional scenario. The mass of the Earth impinging on the stuff around it equally in all directions which has an effect on something coming from any particular direction. This doesn’t ‘disprove’ Newton and straight lines in any way. Something will travel in a straight line unless it’s acted on by another something. The effect on it greater the closer it gets to something which can have an effect on its path shows only that the space between the objects is a something a heavier mass affects more than something lighter.
We see this at every solar eclipse [e.g. at the one in 1919 that made Einstein famous] or when receiving radio signals from spacecraft passing near the Sun. Thus space[time] is observed to be warped. This is an experimental fact. Einstein’s GR theory is the explanation of this [and many other effects that depend on warping].
“Thus space[time] is observed to be warped” – Thus space is observed to be warped, not spacetime, so thank you for the brackets. But as above, it’s still a 3D problem, of surfaces meeting. And all it shows is that the space around the Earth is a something which is affected by Earth’s mass.
that you don’t get it, is not a problem of understanding but of fixation with something you can’t even articulate to make sense.
The fixation, as I see it, is that you have called simple 3D reality 4 by including time and then use only 3D reality to explain it. And then complain I don’t understand.. A 3D reality which stands on its own as I’ve gone through above raises questions enough.
So, what I’m trying to understand is how this mass of Earth impinges on the surrounding stuff. If it is impinging really equally in all directions actually distorting the stuff around it equally in all directions, then any effect it would have at any discrete point is cancelled out. Like a ball just heavy enough to be suspended in the middle of a bath full of water.
Like air pressure perhaps? The weight of the gas Air on the Earth is around a ton/square foot, but it’s said that it is pressing on us equally in all directions so we don’t feel it.
But, like Air pressure, it could be that the stuff around the Earth is exerting pressure equally all around on the Earth as much as it could be that the Earth is impinging equally on the stuff all around.
Anyway, as for something falling to Earth in free fall, it’s still a straight line. The astronaut falling to Earth doesn’t get sucked into a ‘vortex’, if such exists by the warping, at any point because his mass is heavy enough to counter any such, a smaller photon might get caught up in such, but we know that light from the Sun comes to us in a straight line, don’t we? And it doesn’t go into an orbit around the Sun after escaping from it as radiation.
You see, in physics, the criteria is not if something makes sense [quantum mechanics does not], but if it has predictive power.
? I thought the point of science was to understand our natural world, how it worked. You may well be able to predict something but attributing it to the gods, but that isn’t an answer of how it works.
GR predicts a frame dragging of a certain size. The experiment that is the topic of this thread has measured just such an effect in accordance with the prediction. This gives us confidence that the equations are a ‘correct’ description of how Nature works to the accuracy we can currently observe.
Does it? All it shows it seems to me is whatever you have taken as ‘time’ in the ‘space/time’ you call warping, which is really only a 3D model of an object with mass in stuff, is irrelevant to the effect of warping. Except in that the speed of a lighter object is less affected by the mass of a heavier body the further away it is from it.
Doesn’t prove time speeds up, but only that an object can go faster the further it is from a force which can slow it down. I read the page on time linked above. And I couldn’t find anything in it that showed time is affected, only speed.
Leif – re my: “Which means that all the directions cancel each other out and there is effectively no warp, because an object approaching it will be ‘passed’ from one warp to the next.”
Sorry, thinking of something else while typing another. If all the points are equally impinging so there’s no actual ‘vortex of gravity’ at any point, then it’s the spin of the Earth which is disturbing the stuff around it, and so something’s path could be distorted in approaching Earth, in effect like being passed from one point to the next. How it gets through this is still normal 3rd physics, depending on it own weight and speed. So radio signals can be bent around, to resume after in the same line or become so distorted in the process that they disintegrate into shash.
Isn’t this how light was discovered to be a wave as well as a photon? That it could bend round corners.
Leif Svalgaard says:
May 5, 2011 at 8:12 am
tallbloke says:
May 5, 2011 at 8:04 am
I guess in order to ‘rescue the data’ the scientists must have found some systematic ‘aberrations’ in the gyroscope headings. Have they documented those and found satisfactory explanations for them?
In order to interpret the data you must first understand your instrument. Such understanding often comes after the experiment when unexpected effects show up. But, yes, they have documented this and, more importantly, understand why they occurred.
Terrific. Where is this documented so we can have a look?
In many cases, Dr. Svalgaard doesn’t give meaningful answers or explanations. Factual content of his posts, if you look beyond the obfuscating jargon and painful reiterations of the obvious, is difficult to discern.
Dr. Svalgaard repeats textbook definitions and/or gives you a link to a Wikipedia article that contains a textbook definition — or, if you insist on clarification, pretends to misunderstand your question (while totally lacking a normal sense of humor — recall how he repeatedly failed to recognize an obvious sarcasm).
Earlier, I asked a question: “So, the flow of time depends on the presence or absence of a large mass in vicinity. Why this is never taken into account when they talk about red shift?”
Dr. Svalgaard answered: “It is.” And, in support of his learned opinion, he directed me to the Wikipedia article on gravitational red shift effect.
Unfortunately, the article that he recommended as an answer doesn’t contain a single word about how, exactly, the gravitational red shift is being taken into account by the proponents of the Big Bang dogma. This was a regular non-answer from Dr. Svalgaard, just a waste of words and time, spiced up by unwarranted condescension and inflated self-esteem.
Whatever Dr. Svalgaard tells you, take it with a pound of salt. Recent discovery of the super-massive cluster of galaxies on the edge of the IR-visible Universe makes abundantly clear that the Big Bang hypothesis is fundamentally flawed. And yet, Dr. Svalgaard continues to lecture us in the same manner, as if his BBT dogma is as immovable as the space-time itself.
The issue of time vs change is discussed here for all you time deniers :p.
http://telicthoughts.com/philosophy-and-metaphysics-interlude-creation-ex-nihilo-vs-change-2/
Anthony,
Science still has not included the forward momentum of the solar system to be of any consequence. So, motion is not included.
Changing of circular motion speeds also changes the gravity being felt as now centrifugal force has increased or decreased.
Global rotation is far more complex than a circle on a single plane in motion.
Jupiter mass is more than 300 times the Earth’s, the surface gravity is ~2.5G. Jupiter’s orbit is the place where theory will be conclusively verified or dismissed.
Joe Lalonde says:
May 6, 2011 at 5:12 am
Anthony,
Science still has not included the forward momentum of the solar system to be of any consequence. So, motion is not included.
Changing of circular motion speeds also changes the gravity being felt as now centrifugal force has increased or decreased.
Global rotation is far more complex than a circle on a single plane in motion.
~
good comment.
Alexander Feht says:
May 6, 2011 at 4:53 am
~
Some of us here need a little textbook knowledge and subsequent explainations as given by Dr. S.
And for the record I personally have never been on my knees before him.. lol did I say that..whooaa..Happy Friday..
Myrrh,
You have articulated a question that I have often thought about. For what it’s worth, here’s my take on the warping of spacetime.
As I understand it, I think you are correct – 3d space is not warped – that wouldn’t make sense. The presence of matter makes time run slower and therefore what is being warped is time. You have to think of 4d space-time that is being warped, and the warping is because of the time dimension, not the 3 spatial dimensions. A particle curves towards the Earth because time is running more slowly closer to the Earth. It is a rule of GR that a particle will move from one place to another so that a clock carried on it will show a longer time than it would on any other trajectory. This is a reason why the particle moves towards the Earth. If it didn’t do so, its clock would show a shorter time. From the framework of 4d spacetime, we say that the particle is following the shortest distance in spacetime – ie, a straight line through spacetime – and in doing so the particle moves in a curve through space, but the space itself isn’t warped.
On spacetime: http://www.ws5.com/spacetime/ which has many good links. Especially this one: http://www.perimeterinstitute.ca/Outreach/Explore_Our_Universe/What_is_Warped_Spacetime?/
Some people apparently just can’t accept reality. Einstein’s special & general relativity make extremely precise predictions — if results are even slightly off, his theories would be toast. So far, every prediction has been verified.
No one says relativity is complete — it’s not meant to address the very tiny scales. That’s different from being wrong, just incomplete.
Again: this needs unpacking. If you’re wondering why you’re being ill-treated, it just might be the glib arguments-by-assertion.
If you seek to illuminate, by all means have at it. What you’ve been doing looks more like trolling, from where I stand.
FWIW.