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NASA Probe Validates Einstein Within 1%
An anonymous reader writes "Gravity Probe B uses four ultra-precise gyroscopes to measure two effects of Einstein's general relativity theory — the geodetic effect and frame dragging. According to the mission's principal investigator, the data from Gravity Probe B's gyroscopes confirm the Einstein theory's value for the geodetic effect to better than 1%. In a common analogy, the geodetic effect is similar to the shape of the dip created when the ball is placed on to a rubber sheet. If the ball is then rotated, it will start to drag the rubber sheet around with it. In a similar way, the Earth drags local space and time around with it — ever so slightly — as it rotates. Over time, these effects cause the angle of spin of the satellite's gyroscopes to shift by tiny amounts." The investigators will be doing further data analysis over the coming months and expect to release final results late this year.
That project took way too long. I remember people working on it when I went through Stanford in the mid-1980s. It was something of a boondoggle; it mostly produced students, not flight hardware. I'm glad to hear it finally worked, though.
... balls on rubber sheets. Seriously.
True, it did take a while. But I'd like to think it was worth the wait. Also, for those who care, here is a link to the Stanford page http://einstein.stanford.edu/ it has the same info as the article along with more stuff about the project.
Actually people have been preparing this experiment since the 1960s.
There was a great lecture about this on this year's hungarian skeptics conference, spiced with the real life experience that Hungary was part of the soviet influence sphere at that time, so when one physicist was allowed to go to the USA for a year to do research. When he came back, his colleagues were flocking him, discussing the news and that the americans are setting up this experiment. The lecturer, now an old man, can finally see the result of the experiment they were discussing more than 40 years ago.
It takes a man to suffer ignorance and smile
Be yourself no matter what they say
I spent a week watching all the Nova PBS episodes, learning about this and string theory. Even though I'm not a mathematician or physicist, it certainly caught my attention.
http://www.pbs.org/wgbh/nova/elegant/
"To be is to do." -Socrates
"To do is to be." -Jean-Paul Sartre
"Do-be-do-be-do." -Frank Sinatra
If I put three gyroscopes, each spinning in a different axis at right angles to each other, into a box, wouldn't its increased inertia make it just seem more massive? How does the momentum of all those electrons and other subatomic particles spinning around contribute to its apparent mass?
--
make install -not war
This was not a NASA experiment per se, it was a Stanford experiment. The original press release can be found here. The official stanford website also lists preliminary findings here.
While I don't believe Tesla actually said it, I've often seen him credited with the phrase "If only Mr. Edison would a bit smarter, he wouldn't need sweat so much."
>> genius is 1% and perspiration is 99%.
My sweaty Uncle Phil must have a 198 IQ.
This seems like a waste of money and resources. As any creationist will stress to you - gravity is only a THEORY.
Let me see if I understand you: is this similar to the mall thing where you throw coins into it and they go round-and-round until disappearing into the hole below? If it is, then...I...waitaminit...we're all going to die!
sciency details:
d _einstein_iv_showdown_in.php (April 4)
http://cosmicvariance.com/2007/04/15/dragging-on/ (4:33 p.m.)
Also of interest if you're into this sort of thing, what Beyond Einstein programs will be cut?
http://scienceblogs.com/catdynamics/2007/04/beyon
sad if you compare sticker prices to the $10 billion per month on the Iraq adventure.
If you need text styles to communicate then you don't have a message.
with regard to this. This isn't someone claiming ID causes the universe to act as it does, this is FSCKING Einstein. That he is proved correct is more about man understanding the universe, and relying less on the theory that it is too complicated to understand and must have been created by an imaginary being. This *IS* news, and should be heralded appropriately.
While some might think me a troll, think about it, Einstein was right. That means that we are that much closer to understanding how the universe works. Even 100 years ago such progression could only be imagined, not proven. In the time that we live in, science books have to be revised every year not because of a need to spend government money, but to actually keep them up to date!
So much change and investigation. People have become numb to the actual changes.
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I assume this is the project: http://en.wikipedia.org/wiki/Gravity_Probe_B
g ravity_probe_b.jpg
And the probe itself is just astounding: http://en.wikipedia.org/wiki/Image:Einstein_gyro_
The thing is that this effect has been tested at strong gravity. There is no dispute that GR is not correct in the strong gravity limit. The strength of GR is only disputed at weak gravity, or near Planck's length. It is a good verification of GR, but I don't think anybody thought that it will not be vindicated.
We need a probe to test GR at L1 point if the gravity there is significantly weaker than a0 to distinguish between MOND and DM. This IMHO is the most important test. If it is not possible to test MOND at L1 point, because the MONDian bubble is too small then there is no hope for a test within the next decade. Because that is how much time a very modern satellite will take to reach beyond the solar system where the gravity is significantly weaker than a0.
Firstly, I'm going to guess that frame dragging is verified at no better resolution than the curvature of space/time, but that as far as they can tell, it exists and meets the values expected by Einstein.
Frame dragging is the name of one particular way in which spacetime curves. It is curvature. To say something about frame dragging or curvature is to say something about the other. I don't know if the parent statement makes sense or not. The group has not released their frame dragging measurements yet, just the geodetic precession measurements (the precision of which will likely go up as they isolate more systematics in their data as they move toward making a statement about frame dragging). Frame dragging is about 100 times harder to measure than geodetic precession, for the mass and spin of the Earth.
Secondly, I'm also going to guess that QM experts will start to get a little nervous. The properties any future QM model of gravity must have contradict the GR model. They cannot both be right. The more "right" the GR model, the more problematic a QM model. This doesn't mean a QM model does not exist, only that it is most undesirable (from a QM perspective) for the GR model to make highly precise and accurate predictions.
GR is arguably the most successful physical theory to date (I would say that electrodynamics rivals it since it has been formulated classically in curved spacetime and also has been quantized successfully in flat spacetime, but that is another discussion). Newton was not "right", but note that GR simplifies to Newtonian mechanics in the weak field and non-relativistic limit. Any theory which supersedes a highly successful physical theory must reproduce said theory in the proper limits. A quantum theory of gravity must reproduce GR in the macroscopic limit, just as quantum mechanics has a correspondence principle which allows it to reproduce classical wave and particle phenomena in the appropriate limit. I don't think any physicist is nervous about these results - everybody expects GPB to verify the predicted frame dragging. Deviations from the values predicted would excite fans of MoND, SVT theories, and other alternative theories of gravity.
Thirdly, frame-dragging occurs at a non-zero distance from an object.
Frame dragging curves spacetime globally, but falls off to asymptotic flatness. The parent statement probably makes sense.
This doesn't matter, for the purpose of these observations, as they're nowhere near accurate to measure the relativistic effects that apply to the information passed that creates the effects in the first place. Nonetheless, such an affect must exist, or you'd end up with infinitely fast rates of change of state, which is expressly forbidden in GR.
The NSF and NASA don't spend this much money to throw an instrument into space unless they think it will actually measure what it's supposed to. The gyros are the most spherical macroscopic manmade objects, which used superconducting quantum interference devices (SQUIDs) to precisely measure their precession, blah blah blah, read about it on their web site. I sure hope they're accurate enough to measure those relativistic effects, because that's exactly what they've been designed to do. I don't know what information you are talking about. The Einstein Field Equations are local, so there is an inherent limit on the speed at which 'information' (curvature) propogates through spacetime.
It's a gross simplification and it's not an "obvious" conclusion to reach by any means, but if the curvature (and restoration) of space/time has nothing analogous to Hooke's Constant, then after a gravitationally massive object has move
-Leo
Glad it worked? I'm horrified it worked. /. geek wouldn't know the term) than we thought we were before.
Every time someone (re)validates Einstein relativity theories, we actually know we're one step further from FTL (Faster than light - though I'd be surprised if any
Damm gravity.
When in danger or in doubt, run in circles, scream and shout [Robert Heinlein]
FTL? WTF? Everybody knows that FTL drives are a work of fiction.
No, my friend, what you need is a warp drive.
For some reason the article and summary only mention that Gravity Probe B was trying to measure was "minuscule" however, I at least find the actual quantity to be FAR more impressive than some journalist calling it small. Anyway want to know the precession?
Frame Dragging Effect (has NEVER before been measured): 1.1x10^-5 degrees per YEAR
Geodetic Effect: 1.8x10^-3 degrees per YEAR
Clearly then, these were not merely "minuscule" shifts...the potential for error is great.
More information can be found at http://www.nasa.gov/mission_pages/gpb/index.html
This means that there are no differences between GR and MOND in the gravitational limit that this test has been conducted. This means that MOND will have the same problem that GR has, if the tests don't come out as predicted. I guess in this case the tests will be considered to be faulty, as there are literally no theories (that are not considered crackpot) that give different results different from GR in the strong field regime. So the tests by Gravity Probe B will not make any difference, though it probably will give GR theorists something more to brag about.
There is a big misconception about MOND, that it is a theory. It is not, it is a law that works very well at the Galactic Level and somewhat at the cluster level. MOND fits all galactic level data to the limit of their expected accuracy. This it does so with a single universal constant. But nobody knows why it works so well.
As such it is very obvious there is something behind MOND. GR cannot explain MOND without fine tuning DM in such a way to give rise to MOND. But since MOND uses only Baryonic matter, it leaves DM with no degrees of freedom, which is not possible, so DM must not exist at the Galactic level.
At Cluster level situation is different MOND does not match up with the missing mass. Which means either there is Dark Matter at the Cluster level or MOND itself is a reasonable approximation of the correct theory of gravity only in the galactic limit. Beyond the galactic level it ceases to be a good approximation.
If there is dark matter at the cluster level then there must be a reason why it does not exhibit itself at galactic levels. This would meant that the dark matter is hot and moving at a high velocity, which allows it to form stable structure only at the cluster scales.
The interesting thing about the universal constant (a0) of MOND, is that if a particle is accelerated by a0 for the whole life of universe then we will get the speed of light. This would seem to provide a hint that a0 is due to the curvature of the universe.
This actually solves a problem in GR. If GR is absolutely correct then the curvature of the universe cannot be determined, which is also called the flatness problem. This problem is currently avoided by assuming that there was an inflationary era when the universe expanded so much that we only see a very small part of the universe which is flat. So that GR equations are correct. But if that is not true and the universe is not really that big then GR will break down because of no fault of itself, but simply because of the curvature of the universe.
So in my opinion GR is correct but the curvature modifies GR in such a way that we observe MOND.
Actually, considering that Edison is famous for:
- taking credit for his employees' inventions as if he personally and singlehandedly came up with them. (There are at least 28 inventors that Edison ripped off this way, including for example taking credit for inventing the motion picture camera. Actually, it was invented by W.K. Dickson.)
- patented stuff he didn't actually have yet, and/or wasn't even original
E.g., he applied for a lightbulb patent a full year before actually having a filament that was commercially viable: and Edison's, or shall we say, his teams, _only_ contribution there was a commercially viable filament. The light bulb as such had already been discovered, it just didn't last long enough to be worth buying. But wait, even the carbon filament wasn't new: Edison't patent application itself had come a whole 1 year after Joseph Swan had patented a working model in England (and was working at it since 1850, 28 years earlier). So basically it took Edison and his team two years to copycat someone else's invention and claim credit.
- bogus patents, e.g., a number of patents on ornamental designs
- using PR and bad science to win public support: see the "war of the currents", where Edison (who wanted to sell direct current) paid people to roam the country and conduct demonstrations of killing cats, dogs, and once even an elephant with alternating current. Just, you know, to show people that alternating current kills. (While supposedly his direct current at the same 110V doesn't. Yeah, right.) He's also the author of the electric chair, as part of the same campaign to prove that AC kills. The first execution had the guy pretty much fried alive over a time of more than a minute (he certainly was still alive and struggling after the first 17 second jolt), in a show that sickened spectators and was described by the New York Times as, "an awful spectacle, far worse than hanging." That's the kind of PR that served Edison's purposes.
- shafting the employees. E.g., Tesla was promised a (huge for that time) bonus of $50,000 if he succeeds in making an improvement to the DC generators. When he actually succeeded, Edison didn't pay him, and in fact told him, "When you become a full-fledged American you will appreciate an American joke." In fact, he even refused to at least give Tesla a raise.
- mis-treating his employees. They actually spread word of Edison's current mood, so they'd know to duck for cover if he's in a bad mood.
- speaking of Tesla, here's one thing he said about Edison's dumb trial-and-error methods, a.k.a., 99% perspiration: "His method was inefficient in the extreme, for an immense ground had to be covered to get anything at all unless blind chance intervened and, at first, I was almost a sorry witness of his doings, knowing that just a little theory and calculation would have saved him 90 percent of the labor. But he had a veritable contempt for book learning and mathematical knowledge, trusting himself entirely to his inventor's instinct and practical American sense." (Would explain why most "Edison" inventions were actually from employees who actually understood what they're doing.)
- various attempts at monopoly, including the infamous "Motion Picture Patents Company", a.k.a., the Edison Trust. You know, if you thought that MPAA is bad, the MPPC meant you couldn't even make independent films without Edison's blessing.
- showing more contempt to the artists than the RIAA today, and in fact, enough to make the RIAA look like the good guys. Edison refused to even print the artist's name on the label. You're buying Edison music, you peon, not some artist's music. On one occasion he stated, "I would rather quit the business than be a party to the boasting up of undeserved reputations." Yeah, who do you think you _are_ to be getting any reputation for your talent and popularity. Only the great Edison should get a reputation out of it.
- letting his personal moods and preferences be the only criterio
A polar bear is a cartesian bear after a coordinate transform.
I don't think anyone's concerned about proving Einstein absolutely right or absolutely wrong—if you look at it in those terms, any theory is bound to be proved "wrong," eventually, in that it'll fail for some ever-increasing standard of precision. What's news here is that we can now trust Einstein's equations to predict our measured reality within that cited "1%," confirming that general relativity is a pretty damn useful model. But that doesn't mean it won't be supplanted next year by something even more useful.
Make Slashdot readable! See journal.
Basically, the mission hasn't yet succeeded, and it doesn't seem to be completely certain that it will.
/ ExperimentError.pdf) has a one-sigma error of 100 milli-arcseconds per year, significantly larger than the relativistic effect and significantly larger than the effect from the motion of the target star through space. The initial expectation was for an error budget of less than 0.5 mas per year, so there was a lot of work done on measuring the proper motion of the star to that precision.
The goal was to measure the frame-dragging effect of the Earth, which is of the order of 40 milli-arcseconds per year; the current calibration (http://einstein.stanford.edu/content/aps_posters
The problems turn out to be really crazily subtle issues in solid-state physics -- the deposited metal films on the gyroscope and on its housing retain charge in patches large enough that they have to be modelled rather than averaged out -- plus an annoying issue from classical mechanics where the motion of a rigid body around three axes XYZ depends on the ratio of the differences of the moments of inertia X-Z and Y-Z. Whilst the gyroscopes are absurdly precisely made, so the moments of inertia are very close, the ratio of the differences of the moments of inertia is a macroscopic number; this is the same effect, and even a similar cause, to some of the oddities with low-precision floating-point arithmetic.
They'll probably be sorted out, sigma might be reduced by a factor ten after another year's modelling effort, but it seems unlikely that they'll get it down by the factor 200 they were hoping for.
The frame-dragging has already been measured indirectly by looking at the flickers of X-ray sources caused by frame-dragging-induced precession of the accretion discs around black holes, and most of the theories that suggest relativity is wrong would suggest that any oddities would be more pronounced in the huge gravitomagnetic fields near black holes than in the tiny fields near a mass as small, as non-dense and as slowly rotating as Earth.
Boss, I was late to work this morning because of frame dragging. I would have been here earlier if spacetime hadn't been warped and then twisted by my car.
Peter
Downsize DC Today!
Warp drives are so 1960's you need either slipstream or even better.
An oscillation overdrive. That would be exactly what you need.
Now to find that rock and roll physicist that has the prototype.
Do not look at laser with remaining good eye.
Bingo !
I was going to post this myself. The goal was to measure frame dragging. The geodetic effect has been measured before (LLR and binary pulsars),
and is not nearly as interesting (i.e., its hard
to see why you wouldn't have it). It's the frame dragging that motivated the decades of effort and expenditure.
If they can't do frame dragging, the experiment will be deemed a failure.
naw, a Bergenholm is what you need
No! We fold space! Or better yet: we actually build the improbability drive! ... and put the engine to Ludicris speed! ??!?!?
Ptolemy said the planets circled the Earth in epicycles, and mathematically "proved" it to the accuracy of available instruments. This was good enough for about a 1000 years. Together, Newton and Galileo proved heliocentricity, but calculated ellipitical orbits, also wrong, and also within the accuracy of available instruments. Brahe and others eventually measured things so precisely that they were able to find that Newton had an error, but they didn't understand it. Later, someone (I forget who) was able to measure the orbit of Jupiter's (known) moons and show that the speed of light caused an apparent lag in their orbital motions. But planetary orbits still didn't obey Newton precisely.
The world had to wait for Einstein to get an explanation - space/time curvature, etc, predicted the variance from Newton's calculations.
Somewhere in all of this, British scientists predicted the existence of Australia by the wobble it causes in Earth's spin.
Failure of real world measurements to match theoretical predictions can lead to greater discoveries. Sometimes the failure is more significant than success would be.
Pavlov wouldn't be so famous if he'd used a can opener instead of a bell.
http://en.wikipedia.org/wiki/Zeno's_paradox
Pavlov wouldn't be so famous if he'd used a can opener instead of a bell.
1) your sig has a very lame typo 2) take comfort in the 1%.
First we had the deistic theory of physics - things fall because they fall, big guys hit harder because they're big, and so on.
Then we moved up to Newtonian physics.
Then Einsteinian.
Who's next? Bohr? Someone I've never heard of? Who knows, but it's an interesting question.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
>Who moded this person a troll, without posting a response?
You can't mod and post. One or the other, but not both.
Some mornings it's hardly worth chewing through the restraints to get out of bed.