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Space Science

NASA Probe Validates Einstein Within 1% 188

Posted by kdawson
from the kind-of-a-drag dept.
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.
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NASA Probe Validates Einstein Within 1%

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  • by Animats (122034) on Monday April 16, 2007 @11:52PM (#18762597) Homepage

    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.

  • by A beautiful mind (821714) on Tuesday April 17, 2007 @12:01AM (#18762693)
    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.
  • by creimer (824291) on Tuesday April 17, 2007 @12:10AM (#18762775) Homepage
    Thomas Edison said that genius is 1% and perspiration is 99% []. It's nice to see scientists proving him right.
  • by zappepcs (820751) on Tuesday April 17, 2007 @12:52AM (#18763069) Journal
    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.
  • by zappepcs (820751) on Tuesday April 17, 2007 @01:30AM (#18763363) Journal
    My friend, don't be fooled. One step closer to understanding how the universe works is one step closer to proving that irreducible complexity is as mythical as the flat earth, the perfect sun, or that the earth is the center of the universe.

    Not all religions think that technology is evil/pointless, but the ones that are most dangerous do. This doesn't disprove the existence of god, or prove it. It disproves irreducible complexity, and thus the theory of intelligent design. ID is that theory that would not explore or experiment because it cannot be understood, things just are because god created them that way. Evolution didn't happen, the big bang didn't happen... all that claptrap. god may well exist, and may well have caused the big bang, or the chain of evolution to begin... who knows. The point is that understanding how things work is important to us as a species. Those that would oppose such investigations and the evidence they produce are dangerous to all of us. Scientists are heroes. Not even 1000 years ago men were killed or imprisoned for knowing less than we take for granted as common knowledge today.
  • by LionMan (18384) <> on Tuesday April 17, 2007 @01:56AM (#18763577) Homepage Journal
    It distresses me a little to see a post modded so highly just because it throws together the right words; but I suppose that says something about me as well, given my choice of forum. Anyway, since I nominally study gravitation, I feel like I should clarify some things in a reply.

    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

  • by Zaph0dB (971927) on Tuesday April 17, 2007 @02:12AM (#18763691)
    Glad it worked? I'm horrified it worked.
    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 /. geek wouldn't know the term) than we thought we were before.

    Damm gravity.
  • Actually... (Score:5, Interesting)

    by Moraelin (679338) on Tuesday April 17, 2007 @04:53AM (#18764665) Journal
    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
  • by Tickletaint (1088359) on Tuesday April 17, 2007 @05:09AM (#18764751) Journal
    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.
  • Re:oops (Score:3, Interesting)

    by mbone (558574) on Tuesday April 17, 2007 @10:03AM (#18766685)
    This disappointment was actually predicted over a decade ago.

    The snarky joke was that this was truly a null experiment : if it agreed with General Relativity, it would be believed, but it would change nothing. If it did
    not agree with General Relativity, it would be viewed as being in error until it could be confirmed, which would likely take more decades. So, no matter what the result, it wouldn't change fundamental physics, which was the whole point.
  • by Anonymous Coward on Tuesday April 17, 2007 @10:44AM (#18767379)
    Unfortunately, the string theory he's pushing is unverified, essentially untestable, incomplete, and nowhere near as elegant as he makes out.

    String theory is not "untestable". There are many string models which can be tested (and many of them have in fact already been ruled out).

    String theory may be "incomplete", but it's arguably better than quantum field theory, which is inconsistent — it breaks down at high energies.

    As for elegance, it's also certainly more elegant than quantum field theory. No swarm of fundamental free parameters, no arbitrary and infinite collection of possible interactions, unique and unified description of all interactions, etc.

    In many respects, it's the opposite of elegant: introduce enough degrees of freedom into the equations so that you can solve any problem by tweaking the parameters.

    You can say pretty much the same thing about quantum field theory, as long as you're not talking about problems involving quantum gravity for which QFT fails anyway. You can always add more particles, tweak their interactions and masses, etc.
  • by alienmole (15522) on Tuesday April 17, 2007 @11:52AM (#18768123)

    String theory is not "untestable". There are many string models which can be tested (and many of them have in fact already been ruled out).

    My qualification "essentially untestable" was intended to address this. Sure, there are version of string theory that can be rejected. But positive confirmation of many of the artifacts of string theory seems elusive. Since the margins of this Slashdot comment are small, I'll let Sheldon Glashow respond on my behalf [].

    On the subject of "elegance", in the end, that's largely in the eye of the beholder. One of the reviews of Quantum Field Theory in a Nutshell [] says that "it is for anyone who wishes to experience the sheer beauty and elegance of quantum field theory". I suspect if someone were putting out string theory books more like this than like Greene's, string theory might have better PR. Marketing the theory first to the same laypeople who enjoy Deepak Chopra, and only second worrying about people who might actually be able to understand and critique the theory, is not a good sign.

    Besides, even if QFT is conceded to be ugly, it's useful. String theory still can't compete on that level. Having better theories to replace or augment quantum theory would be fantastic. String theory has had a long time to achieve that, but the results haven't been very good, and we have to consider that maybe other approaches deserve more attention. Since Greene opened the door to trial by populism, I'll defer to USA Today [] on this point.

To thine own self be true. (If not that, at least make some money.)