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NASA Science

NASA Gravity Probe Confirms Two Einstein Predictions 139

sanzibar writes "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."
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NASA Gravity Probe Confirms Two Einstein Predictions

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  • by Anonymous Coward on Thursday May 05, 2011 @04:53AM (#36033044)

    Please, can somebody restore the fortune database? Thanks.
    Uh, and First Post.

    • Re: (Score:1, Offtopic)

      by hcpxvi ( 773888 )
      Uh, what he said. I'd mod him up if I had any mod points. Not that I have had any for months, despite excellent karma. The new Slashdot: too buggy to be fit for purpose.
      • by rhook ( 943951 ) on Thursday May 05, 2011 @06:16AM (#36033308)

        The new Slashdot: too buggy to be fit for purpose.

        I have to agree with this, several bugs. The most annoying one is having the comments scroll to the top of the page when I click anything.

        • I know this is off topic, because I need glasses, I use the + and - keys in Opera to zoom the screen a bit. But now ./ does something to ignore those keystrokes. I have to go to Options and toggle filter controls. It doesn't seem to matter if it's on or off, I have to just toggle it to another state. Then it works. A day or so later, I have to do it again..
          • by Shippu ( 1888522 )

            I don't have this problem. It's probably Opera's fault though. For some months I've been wanting to try Firefox/IE9/Chromium because Opera has many unfixed bugs that go back even to version 9. For example, I can't select any text in this text box without doing a right click>select all first. I reported this to them 4 years ago.

        • by amaupin ( 721551 ) on Thursday May 05, 2011 @09:48AM (#36034508) Homepage

          I have to agree with this, several bugs. The most annoying one is having the comments scroll to the top of the page when I click anything.

          Links are now unclickable, at least on the first 4 or 5 tries. Each time you click a link in someone's post, the page jumps and/or another post expands/collapses. The sheer level of ignorance and/or lack of interest in their own site on the part of the Slashdot owners is mind-boggling.

          (Click on links? I must be new here.)

          Seriously, Slashdot, fix your goddam site.

        • by Ogive17 ( 691899 )
          I'm curious why /. looks like shit while using IE8 or Firefox but looks pretty good on my Droid X's native browser. I was browsing from my phone during a phone conference yesterday and couldn't believe how functional the page looked.
          • Um, maybe the developer uses a Droid X for development work.

            That would explain quite a lot actually...

        • by Xacid ( 560407 )

          And here I thought it was just my fault for not using IE...

        • by Hatta ( 162192 )

          Mark as untrusted.
          Switch to classic discussion mode in your preferences.

          • by JWW ( 79176 )

            Couldn't agree more.

            EVERYTIME /. upgrades the first thing I do is go back and turn classic discussion mode back on.

        • dont click anything. CmdrTaco --sent from my iPhone
    • by sjwt ( 161428 )

      no, but I can link to the related saturday morning breakfast cereal comic.

      This is why experimental scientists hare theoretical scientists []

    • by dotancohen ( 1015143 ) on Thursday May 05, 2011 @08:47AM (#36033992) Homepage

      Please, can somebody restore the fortune database? Thanks.
      Uh, and First Post.

      Restore it? It works fine for me, here:

      Are Linux users lemmings collectively jumping off of the cliff of reliable, well-engineered commercial software?

      In fact, I've been seeing that for a few days!

      Protip: Say that quote while walking the halls. You will immediately know who your fellow /.ers are by the snickers. If your boss laughs, then you're in trouble.

      • Are Linux users lemmings collectively jumping off of the cliff of reliable, well-engineered commercial software?

        Protip: Say that quote while walking the halls. You will immediately know who your fellow /.ers are by the snickers. If your boss laughs, then you're in trouble.

        Well, I'd laugh at that quote -- specifically, the presumptions it implies.

  • Honey? (Score:4, Funny)

    by mangu ( 126918 ) on Thursday May 05, 2011 @05:09AM (#36033112)

    "Imagine the Earth as if it were immersed in honey," Francis Everitt, GP-B principal investigator at Stanford University in Palo Alto, Calif., said in a statement

    Doh, this is Slashdot, we want a car analogy, please. And have the numerical results expressed in libraries of congress per football field. Thanks.

  • OK, geodetic effect, check. Frame-dragging, check. Commence dev. project warp drives
    • by roger_pasky ( 1429241 ) on Thursday May 05, 2011 @06:21AM (#36033332)
      Agreed, make it so. Geordi, estimate developement period from current stardate. Data, start doing some calculations. Wesley, contact Dr. Sheldon Cooper and piss him off.
  • NASA and the USA (Score:5, Insightful)

    by mustPushCart ( 1871520 ) on Thursday May 05, 2011 @05:22AM (#36033158)

    I am not an American, but I have seen both the blue pearl image and the pale blue dot image. I have read about how long these projects have run and the astounding quality of the instruments that must be on satellites like these along with the massive foresight it must have taken at launch time to make them relevant decades later. You can criticize the USA all you want for their wars, and I have heard some harsh criticism of NASA too but the most astounding images and discoveries have always come from the here because they are on the pinnacle of space exploration. The world would be a lot less interesting if it wasn't for them.

  • by Anonymous Coward

    Have you seen the comments in TFA by this David de Hilster guy? What a fruitloop. Check out his picture []. Want some love particles, baby?

  • by a_hanso ( 1891616 ) on Thursday May 05, 2011 @05:53AM (#36033256) Journal [] has a simple animation explaining the gravity probe B experiment.
  • That's great... but given a quantum physics and that little bugger of a concept known as the observer effect (basically ALL experience is subjective to the observer - even scientific ones...) how do we know the results we are recording are actual vs what we believe we should be experiencing and therefore are willing to see? Sure I could be wrong in what I am saying, but let me know and I'll entertain it in my field of awareness as possibility and perhaps I'll experience it differently...or maybe not. ;) Y
    • by sandytaru ( 1158959 ) on Thursday May 05, 2011 @08:40AM (#36033938) Journal
      The effects of gravity are at macro scales, not quantum scales. From what I understand, the observer effect doesn't really kick in until you start talking about stuff smaller than atoms. The universe is a bit more well-behaved at scale sizes larger than an atom, where chemistry and classical physics kick in. Our other end of non-understanding doesn't start until you get to the very macro, all the dark matter and dark energy floating around out there that no one really knows anything about.
      • Exactly. Quantum mechanics only starts to be noticeable about ~50nm or so. In contrast, gravity is normally only noticeable with objects best measured in yottagrams (that's "quintillions of tons", for those of us a bit fuzzy on the extreme SI prefixes).

        Now, there's been a huge amount of speculation as to how the two combine, especially from theoretical physicists like Dr. Hawking. However, there have been absolutely no experiments in quantum gravity, for one simple reason: the only time you get that much
        • In contrast, gravity is normally only noticeable with objects best measured in yottagrams

          1.61lb is considerably less than a yottagram. Cavendish Experiment []

          • Yes, and that experiment required some of the greatest precision technologically possible at that time. I'm talking objects big enough that the force of gravity they exert is clearly and immediately obvious, just as I was talking about quantum effects only being clearly and immediately obvious below 50nm. You can certainly detect both phenomena at lower masses or greater distances, but that is hardly relevant to the discussion of practical effects.
      • The effects of gravity are at macro scales, not quantum scales.

        The effects are on all scales. Just because nobody can currently describe how a single photon warps space as it travels does not mean it does not occur. We know it does.

    • by blueg3 ( 192743 ) on Thursday May 05, 2011 @08:55AM (#36034052)

      t (basically ALL experience is subjective to the observer - even scientific ones...)

      That's not part of quantum mechanics at all. That's a gross generalization made philosophical that arose out of an actual quantum mechanical principle.

      Measurement-related QM principles, like wavefunction collapse and Heisenburg, are only meaningful when what you're observing is the size and scale of a quantum state, which is very, very small. Gravitational effects are for the most part (and in this case) for large objects, where QM principles are unimportant.

      • by qc_dk ( 734452 )
        And it could also be related to a gross misgeneralization of the theory of relativity. Which basically states the exact opposite: That any careful observer in any frame of reference will agree on the value of the speed of light and the laws of physics. A better name would have been the theory of constancy.
        • It depends on your perspective. It's "relativity" because most measurements you make *are* relative to your reference frame, only the speed of light (and various invariant quantities) are absolute.

          The relativity that SR and GR deal with is different in kind than the "peculiarities" of quantum mechanics. And, the previous post was correct: the observation-related uncertainties of QM are (mostly) only important when systems get to microscopic scales. Yes, the same microscopic laws apply to macroscopic phys

        • by blueg3 ( 192743 )

          Only observers in inertial reference frames agree on the laws of physics, no?

    • by Anonymous Coward on Thursday May 05, 2011 @08:58AM (#36034090)

      You need to actually study quantum physics if you want to talk about these things like an adult. It's obvious to everyone that HAS studied quantum physics that you're spouting nonsense and claiming that Science supports you. Quit watching "What the bleep do we know?". It's full of people lying to you to sell you an idea (and one scientist who was duped and every single quote taken out of context).

    • by xehonk ( 930376 )

      The observer effect is not something specific to self-aware observers. It can simply be interaction with other matter - which has then "observed" the item in question.

      Now with that out of the way, what you want to happen has no influence on what does happen. That's simply not what the observer effect is about.

    • by tm2b ( 42473 )
      Sorry, you're making a comment on Quantum Mechanics. I am going to have to ask to see you explain any version of a Schrödinger equation, or ask you to stop.

      That should really be a law.
  • I usually bow out of stories like this, but must make one comment:

    Anybody who thinks time is important as a metric is seriously missing the point.

  • ... but the Chinese are actively doing it - as seen here in 2007 [].
    Sometimes we to just shut up and do it else we'll have deja vu like solar energy [] or nuclear power []
    • I'm sorry, I posted this comment to the wrong article... sigh.
      • But your first post got Score:1 and your second got Score:2. I think the day is about here when the long running two-million monkey experiment that is will be shut down.

        Oh, and thank you, Dr. Einstein, for thinking about this stuff and putting it in a form that could be challenged experimentally.
  • Finally I can put an end to all of those naysayers of gravitation theory!

    • Look - it's just at THEORY - you admitted it yourself right in your post. Go find some facts and get back with me. I've got a Bible full of them right here at my desk, and there isn't a single mention of gravity. I can't believe you're still blathering on about this... ;-)

    • Now if I recall correctly, they were also looking for the existence of gravitational waves.. which they.. didn't find.. correct?
  • by Greyfox ( 87712 ) on Thursday May 05, 2011 @09:21AM (#36034254) Homepage Journal
    Relativity and black holes look like bugs in a not-very-well thought-out physics simulation. This sort of thing makes me wonder if the universe isn't just some extra-dimensional college kid's thesis project on how to find the best way to turn hydrogen into plutonium.
    • In the beginning, Bob created the heavens and the earth. But his emulation of Newtonian physics was but partially implemented, and so he only got a B-.

    • by qc_dk ( 734452 )

      Dear Mr. 94343,

      I would like to thank you for considering our ilustrious instituion. I regret to inform you, however,
      that you have not been accepted to our "Universe creation and it's applications" Ph.d. programme.

      While your admission project did indeed show a lot of practical skill and hard effort, we believe your theoretical understanding is somewhat deficit.
      We asked for the best way to turn hydrogen into plutonium, not iron.

      We encourage you to take another year of theoretical physics, and reapplying for t

    • When I read something like "confirms Einstein's theory" AGAIN I just get annoyed. In my opinion, the mission would only be a success if it found a flaw in Einstein's theories. Those theories are many decades old and I'm hungry for some totally new physics.

      I get so disappointed when I hear that the Pioneer mystery (or whichever one was curving unexpectedly) is solved using perfectly well known physics. Where are the new unknown rules that we can use to create new breakthrough technologies?
    • by notpaul ( 181662 )

      "You see, to be quite frank, Kevin, the fabric of the universe is far from perfect. It was a bit of botched job, you see. We only had seven days to make it."

    • From an extra-dimensional point of view, Hydrogen may as well already be Plutonium.
  • However the Stanford satellite supposedly is ten times more accurate
  • Why it took 52 years (Score:5, Interesting)

    by rotenberry ( 3487 ) on Thursday May 05, 2011 @10:39AM (#36035148)

    From what I have heard, the reason it took 52 years to get this spacecraft into space was political, not technical.

    There is no doubt that the technology developed to measure these parameters is very impressive. The real question is whether or not it was worth the effort.

    When I was at JPL in the 1980s a person who had published numerous papers in both experimental and theoretical relativity explained why scientists within the space program were not supporting this project. Since this conversation took place thirty years ago I must paraphrase:

    "No modern theory of gravity predicts anything else, and if the measurements showed anything but the predicted results it would be assumed to be an experimental error. Unlike the technology used to search for gravitational radiation (which is also used to study the atmospheres of planets), the hardware in this spacecraft cannot be used for any other scientific experiment."

    So for 52 years the money has been used for other science. For a much more worthy project read about the recently canceled LISA project.

    If you wish to read about the politics of how a science project is chosen by NASA I can think of no better description that Steven W. Squyres' "Roving Mars" where he describes how the Mars Rovers were nearly canceled.

    • by radtea ( 464814 ) on Thursday May 05, 2011 @11:48AM (#36035984)

      No modern theory of gravity predicts anything else

      Except Moffat's, of course.

      And while every experimental anomaly is first dismissed as error, the fact (you remember those things, facts?) is that scientists have an excellent record of poking away at anomalies until a robust, consistent explanation is found. Sometimes the explanation is mundane--the Pioneer Anomaly, for example. Sometimes it is profound--the anomalous precession of the orbit of Mercury comes to mind, which was measured quite precisely in the 1850's, if I recall correctly, some sixty years before the underlying cause was found.

      People who say things like this are simply ignorant of the history and timescales on which science actually operates. It is entirely implausible that a group of people who have collectively worked over hundreds of years to account for dozens of tiny numerical anomalies in extremely difficult precision measurements would suddenly throw up their hands and say, "OK, I guess we can ignore the data now!"

      • by Anonymous Coward

        Like everything else, science does not have access to infinite resources. However, posts such as yours remind us there is an infinite amount of testing to do. For example, we could pose the question of whether or not a ball and a feather fall at the same rate as each other on Pluto, if dropped simultaneously. In the case where our need for resources outpaces our access to them, we must prioritize what is important.

        One way of doing this is time and potential for payoff. Consider how many years the hypothetic

    • if the measurements showed anything but the predicted results it would be assumed to be an experimental error

      Very likely, but nobody would have been absolutely sure. Physicists would have looked at possible theories that were in accordance with the experimental results, and come up with other tests.

      The Michelson-Morley experiment was similar in effect. People thought it very odd that it didn't show ether drift, but the theories were firmly established, and so physicists kept worrying at it. More expe

    • So for 52 years the money has been used for other science. For a much more worthy project read about the recently canceled LISA project.

      They cancelled LISA?! D=

      If it's because there's no room in the budget for LISA and a shuttle-derived heavy-lift vehicle, I'm personally going to go kick a bunch of congresscritters in the jewels.

  • Sometimes I wonder if these great minds that pops up from time to time (Newton, Copernicus, Einstein etc) are really one of us. It's funny how they appear, completely revolutionize a field or offer a world changing new perspective and then disappear, just to have us mere mortals work for years and decades to understand, confirm and accept it. Applause again for Einstein, you are a bit creepy to be completely honest.
  • My understanding was that (satellite-based) GPS would give you a drastically inaccurate position reading without an algorithmic correction for frame-dragging. If so, it would seem that part of Einstein's predictions were validated quite a few years ago.

    • by Strider- ( 39683 ) on Thursday May 05, 2011 @01:40PM (#36037490)

      No, GPS does takes General Relativity and Special Relativity into account, and confirms both nicely. Due to the motion of the spacecraft in orbit with respect to us on the ground, one would expect the GPS satellites to lose about 7 microseconds a day. However, because the satellites are further out of our gravity well, General Relativity predicts the satellites will gain about 45 microseconds a day. Basically, this means that if GR and SR were not taken into account, the GPS system would be useless after about 2 minutes.

      Source: []

      However, the effect of Frame Dragging is many orders of magnitude smaller, to the point where it will not have a measurable effect on GPS. To even have a hope of measuring it, Gravity Probe B had gyroscopes made from a set of the most perfect spheres ever manufactured. If you were to scale these spheres up to the size of the earth, the tallest mountain would be less than 1 meter tall.

  • by Required Snark ( 1702878 ) on Thursday May 05, 2011 @02:40PM (#36038456)
    According to this paper [] the Gravity Probe B experiment results were not very useful.

    The goal was to get numerical results to 1% accuracy, and the actual measurements only achieved %19 percent accuracy. This was due to a design error.

    Mechanically, the spheres were the roundest objects ever manufactured, Everitt explained. Were one blown up to the size of Earth, the biggest hill on it would be 3 meters tall. However, trapped charges in the niobium made the gyroscopes far less round electrically; an Earth-sized map of a sphere's voltage landscape would sport peaks as high as Mount Everest. Interactions between those imperfections and ones in the gyroscopes' housing created tiny tugs, and to reach the final precisions, researchers spent 5 years figuring out how to correct for them.

    On top of that, other researchers made better measurements using other much cheaper satellites.

    Gravity Probe B fell well short of the precision developers had hoped to achieve in making the key measurement. Moreover, the project got scooped 6 years ago, when two physicists made a similar measurement using data from much cheaper satellites.

    So they got scooped and their final results were not what they had planned. Not a complete failure, but not a real success either.

  • This is cool news! When I first got deep into physics, I often considered the ideal of; "a hot air balloon floating(not) around an earth without an atmosphere", and "would the balloon be dragged around the plaint as it rotates(by gravity)?", now I feel satisfied that know the answer!

    Which leads to the next n question:

    If you took our solar system and placed it at the most significant Lagrange point between two galaxy's, would our understanding of physical constants change? ;) And also the intermediary

He: Let's end it all, bequeathin' our brains to science. She: What?!? Science got enough trouble with their OWN brains. -- Walt Kelly