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Is the Earth in a Vortex of Space-Time?
da6d writes "Apparently, we'll soon know for sure.... NASA has announced in an article that 'A NASA/Stanford physics experiment called Gravity Probe B (GP-B) recently finished a year of gathering science data in Earth orbit. The results, which will take another year to analyze, should reveal the shape of space-time around Earth--and, possibly, the vortex.'" More from the article: "If Earth were stationary, that would be the end of the story. But Earth is not stationary. Our planet spins, and the spin should twist the dimple, slightly, pulling it around into a 4-dimensional swirl. This is what GP-B went to space to check."
Honestly, this is a cool thing, so i don't mean to demean it. But it's the sort of thing only a geek with more than a passing familarity of physics would get excited for.
I'm sure they thought that 75 years ago about Quantum Theory. This is a relatively big deal even if it isn't sexy. I mean, we have to test these things. How many chances do we get to observe major space-time dilation? I mean, minor stuff with satellites, right? But it's hard to get tests of theories involving planets.
So, your problem with the story is that it's too geeky? Which part of "News for Nerds" is opaque to you?
f -External-Forces Greek chap, but humanity has learned the lack of wisdom of that approach several times over.
Proving things that are suspected to be true is the meat-and-bones of science. After all, they might turn out to not be true. Idle speculation may have been good enough for Aristotle the Things-Will-Stop-Moving-Without-the-Application-o
My other body is also not wearing any.
Only once the data is analyzed will the vortex phenomona considered proven (or disproven, obviously).
Not so obvious. The word 'inconclusive' comes to mind.
Mod down people who tell people how to mod in their sigs
It seems to me that confirming (or refuting) a key prediction of relativity is a moderately good story, at least.
And the brethren went away edified.
What is meant is the following:
One of the exact solutions to the Einstein field equations is a decent assumption for the Earth's (or anything approximately spherical which is not moving relativistically) gravitational field. The curvature of space-time is greater the closer to the center of the massive body. A light ray travelling some distance from the massive body will be deflected from a "straight line" (which is hard to define in curved space).
If you are taking the view that you start rotating the rest of the universe around us, then it is equivalent to having your coordinate system spin around the massive body (well, there is nothing besides the massive body in the universe I am imagining). Physically, light will follow the same path as it did before, since all you have done is redefine the coordinate system, which does not change physics!
Now instead, consider spinning the Earth, instead of the coordinate system. The matter making up the earth now has more energy-momentum (the magnitude of which is a physical quantity which can be measured independent of reference frame, if your frame is freely-falling). Energy-momentum is what causes space-time to curve, so a light ray travelling the same distance from the earth will be deflected by a larger amount, since space will be more curved.
-Leo
Curiously enough Rudolf Steiner once stated that the laws of physics aren't the same everywhere. According to him they gradually change the further you get away from a certain point in space. He said something like:"Very much like the gravity influence of an object declines the further away you get from it, so do the laws of physics change."
This could be the proof of his statement.
We suffer more in our imagination than in reality. - Seneca
No it won't. GR is derived from several axioms - in particular, the assumption that the laws of physics are the same everywhere that they are meaningful. If G Probe B get expected results, then it would back up this assumption, and do disprove Steiner.