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Does gravity swirl?

by SuperM4ssive
Tags: gravity, swirl
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SuperM4ssive
#1
Jan7-13, 10:07 AM
P: 9
I vaguely remember learning somewhere somehow sometime that gravity doesn't just dent space-time inwards, it also swirls space-time just a bit. I remember learning this because it was visually depicted using honey. However, now that I try to find out more, I can't seem to find any reference to this swirling effect at all, either positive or negative. It's simply never mentioned. Is it actually true? And if so, why? Why does gravity swirl?
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DrewD
#2
Jan7-13, 10:14 AM
P: 445
I know very little about GR, but could you be thinking about frame dragging?
http://en.wikipedia.org/wiki/Frame-dragging
DaleSpam
#3
Jan7-13, 10:20 AM
Mentor
P: 16,951
It appears to be correct, but the current precision of the relevant measurement is pretty poor.

http://en.wikipedia.org/wiki/Gravity_Probe_B

As far as "why", science cannot really answer "why" questions, except in terms of a more fundamental theory. Currently, general relativity is our fundamental theory of gravity, so we cannot answer "why" questions about it until we develop a more fundamental theory.

What we can answer is "how". Energy, momentum, and stress all contribute to gravity in GR through the EFE. This is different from Newtonian gravity where momentum does not contribute.

Nugatory
#4
Jan7-13, 10:32 AM
Sci Advisor
Thanks
P: 3,438
Does gravity swirl?

Also check wikipedia and google for the "Kerr metric" and "Kerr black holes"; that's the solution that describes the swirling/frame-dragging effect around a massive rotating body.
SuperM4ssive
#5
Jan7-13, 10:50 AM
P: 9
Aaaaah yes, NASA I love you :D Thanks Dale, you're relation to Gravity Probe B made my missing link: http://www.nasa.gov/mission_pages/gpb/gpb_results.html
dipole
#6
Jan8-13, 11:47 AM
P: 433
Quote Quote by DaleSpam View Post
It appears to be correct, but the current precision of the relevant measurement is pretty poor.

http://en.wikipedia.org/wiki/Gravity_Probe_B

As far as "why", science cannot really answer "why" questions, except in terms of a more fundamental theory. Currently, general relativity is our fundamental theory of gravity, so we cannot answer "why" questions about it until we develop a more fundamental theory.

What we can answer is "how". Energy, momentum, and stress all contribute to gravity in GR through the EFE. This is different from Newtonian gravity where momentum does not contribute.
Do you know more about this missions? How did they account for quadrupole and higher "pole" from the asymmetry of the earth? How did they account for the effects of the sun and moon on the probe?


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