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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.
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.
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
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.
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.
Gyroscopes resist changes in angular momentum, not linear momentum. So it only has increased rotational intertia. If you were measuring the box's mass by trying to spin it rather than push it, then yes, it would appear more massive. But if you just pushed it in a straight line, then it would behave the same as if your gyroscopes were still.
On your second question, electrons and subatomic particles don't really spin, they have orbitals. Electron orbitals are the probability distribution of an electron in a atom or molecule. Take a look: http://www.orbitals.com/orb/ So it's not really like a gyroscope. But that is an interesting question, i.e. Do electron orbits effect the angular momentum of atoms? How would you measure that experimentally? Does Newtonian Physics operate on that level?
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