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NASA Gravity Probe Set for Launch
The Real Dr John writes "NASA announced
yesterday that its longest running program, Gravity Probe B, was ready and
scheduled for launch on April 17th. The project has taken 44 years to complete,
at a cost of approximately $700 million. The reason for the high cost is that
the probe contains the most sensitive gyroscopic equipment ever created, which
will be used to test Einstein's theory of gravity. Einstein predicted that the
gravity created by a large body warped space-time, but he also predicted that if
the large body was rotating it would create a drag effect on space-time
known as frame dragging. Gravity Probe B will be able to test
Einstein's theory using Earth's relatively small gravitational field because the
instruments are so sensitive."
Seems God plays roulette even if he doesn't play dice.
The slightest bit of interference could deem it unusable data with as much precision the gyroscopes will be operating. I have a feeling that even interference they are not thinking about (who am I kidding, this is nasa) such as solar radiation, and the magnetic north shift (which as of late, has been about 10 miles a year) will alter the results of this test dramaticly.
-- johntracy.com, because everybody else is wrong.
i viewed the elegant universe, the other day by brian green, and am currently reading the text, much has changed in theory over the last 44 years, string theory for one, currently holds the possiblility that gravtiy strings are looped and therefore capable of jumping from our current brane/dimension. will this allow and or test for this theory or is the device antiquated before deployment? I guess thats a risk involved with such a long dev cycle. hopefully it will take this into account, or has the CERN project already made this redundant?
The earth is a mass-energy. According to General Relativity, as a mass-energy, it should create a little dimple in the local space-time fabric. It is also theorized that the daily rotation of the earth causes a twisting of the local space-time fabric. This effect is known as frame dragging and it should manifest itself as a force that pushes a gyroscope's axis out of alignment as it orbits the Earth. [GP-B will be using four small, incredibly precise gyroscopes as its main tool for detection of relativistic effects on the local space-time fabric.] Gravity Probe B will attempt to measure the force, gravitomagnetism, giving scientists an important insight into how it might affect objects that are much larger than ping pong balls, such as black holes. At the same time, the gyroscopes will experience a much bigger force - the geodetic effect - which is a result of the warping of space-time predicted by Einstein. This force will tend to push their axes in a direction perpendicular to the frame-dragging effect which allow it to be measured separately. The geodetic effect is hundreds of times bigger than frame dragging and the experiment should measure its size with an accuracy of 0.01 per cent the most severe test of general relativity ever undertaken.
-- johntracy.com, because everybody else is wrong.
Gravity Probe A was the launch of an atomic clock on a suborbital rocket, designed to measure time dilation as it passed into weaker areas of gravity.
I believe it was done in 1976
Frame dragging occurs when a massive object is rotating. It turns out that a when a body rotates, it 'pulls' the surroundng space around in the direction of rotation. This means that if you drop an object toward the rotating body, it will not just fall radially tooward the centre but will aquire a component of velocity tangental to the surface.
Of course, this effect also applies to light rays, so the question of what one would actually see is a bit tricky.
Another situation that 'frame dragging' alters from classical theory is orbits around the body. Imagine an observer fixed at a particular set of coordinates in orbit around a rotatng body. If they send photons in orbits around the body opposite directions, they will not be recieved at the same time; that which travels in the direction of rotation will arrive sooner than that travelling in the opposite direction. In extreme cases, it is possible that the photon opposing the direction of motion, although locally moving at the speed of light, won't appear to move at all from the point of view of a distant observer.
I found the following quote especially interesting:
Francis Everitt, the principal investigator of the project, said: "Aren't Einstein's theories all established and confirmed? After all it was 50 years ago that Einstein himself died and it's 100 years next year when he developed his first theory of relativity. Don't we already know it all? The answer is no."
I wonder what other theories that are generally accepted throughout the scientific community have not been completely tested and/or verified. And, quite frankly, I'm surprised that there isn't much more VC and grant money available to go and do research on stuff like this. Afterall, these projects are quite prestigious.
See article
Professional Wild-Eyed Visionary
From the article :
Since the project was conceived by three scientists after a naked midday swim at Stanford University's pool, more than 1,000 people have worked on the satellite. Two of its founders are dead. More than 90 people have earned their doctorates working on the project.
Naked physicists... wow... with the current administration in charge, this project would have never been approved.
... the project that ate Stanford.
:)
When I was a grad student there, we had a running joke that nobody could get an astrophysics degree without selling at least a piece of their soul to Francis Everett, the chief booster for this project.
I was there when a rogue group suggested that, in the intervening four decades, technology had advanced enough to do the frame-dragging experiment with a laser-coordinated satellite net for half the cost.
We also circulated the "fact" that the GP-B launch date slipped by about 1.05 days per day. A friend defined it as a new universal constant for project overruns...
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