NASA Collects Gravity Data to Test Einstein's Theory

Space.com ^ | November 17th, 2005 | Patrick Barry and Tony Phillips

[facedown]

bump

[PatrickHenry]

SciencePing

An elite subset of the Evolution list. See the list's explanation at my freeper homepage. Then FReepmail to be added or dropped.

[Tarantulas]

I heard the lead NASA scientist is named Zefram Cochrane.

[Zuben Elgenubi]

"Put a spinning gyroscope into orbit around the Earth, with the spin axis pointed toward some distant star as a fixed reference point. Free from external forces . . ."

That's a loaded assumption. Orbiting the earth, external forces would still be acting upon the gyroscope. Earth's gravity (inversely proportional to distance but still significant to at least the moon and beyond), Jupiter's gravity, solar wind, solar particles, impact particles, van Allen belt magnetics, etc. Of course, the whole Milky Way galaxy is gravitationally wedded, as is the local galaxy cluster so I'm not sure how one would design an experiment "free from external forces".

[PatrickHenry]

I think this is the official website: GRAVITY PROBE B.

[Mr_Moonlight]

bump

[phantomworker]

A careful, thorough analysis of the data is underway. The scientists will do it in three stages, Everitt explains. First, they will look at the data from each day of the year-long experiment, checking for irregularities. Next they'll break the data into roughly month-long chunks, and finally they'll look at the whole year. By doing it this way, the scientists should be able to find any problems that a more simple analysis might miss.

Looks like a well-designed experiment...

[Flavius]

my head hurts

[FreeRep]

In short, general relativity predicts that a massive rotating object (like the earth) distorts the space around it in such a way that nearby objects that are locally at rest are actually rotating slightly when compared to distant stars. Now, if we are in one of those time vortex's do we get paid time and a-half?

[Erasmus]

The effect will be very small, so I think it will work out to be time-and-a-quintillionth.

[Physicist]

I'm not sure how one would design an experiment "free from external forces".

You don't have to. That was just put in the article by way of explanation: even if there are no external forces, the axis will precess, because spacetime itself is twisting.

What you need in the real world is an experiment where all external forces have been accurately accounted for.

[VadeRetro]

If they detect the vortex, precisely as expected, it simply means that Einstein was right, again.

Unless it means, "Scientists see what they want to see" blah blah blah! </Luddite_mode>

[solitas]

ping

[solitas]

By doing it this way, the scientists should be able to… stay employed for a long time.

[unlearner]

Unless it means, "Scientists see what they want to see" blah blah blah! </Luddite_mode>

And if the numbers do not match Einstein's predictions we will see "scientists" scramble to suggest convoluted explanations along the lines of dark energy.

Later, truly innovative scientists, ones who appreciate the role of epistemology and philosophy, will step up to the plate and present another elegant solution in the fashion of Einstein.

Then of course, the scientific realists around this forum will take credit and claim another victory for scientific "truth."

[VadeRetro]

When the first cracks in relativity appear, if it ever happens, it will be hard to have the new theory ready to go. That hardly makes the first scientists to address the problem less real than the later ones.

[manwiththehands]

"To measure this angle reasonably well, GP-B needed a fantastic precision of 0.0005 arcseconds. It's like measuring the thickness of a sheet of paper held edge-on 100 miles away."

More money for the Nerds!
More money for the Nerds!

They're certainly better with numbers than our bozos in Washington.

[phantomworker]

What you need in the real world is an experiment where all external forces have been accurately accounted for.

Or at least try to identify the major external forces. The rest could be combined as noise. The question is, in this case, how would anyone know that all relevent forces have been identified and isolated, free from dependence. How would anyone know that there isn't a rogue force out there as yet still unidentified?

[edwin hubble]

This is neat.

We are now performing experiments to test the theories of gravity (general relativity) and quantum mechanics that are approaching 100 years old.

We are now taking data in what have been classic "thought experiments". Gravity Probe B has gyroscopes containing the most perfect spheres ever made.