Can gravitational waves carry momentum, and if so what mass/energy produces it, and is space-time capable of vortex formation? This question is about gravitational waves postulated by Einstein.  


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*Is gravitational radiation a form of mass/energy that can form momentum?  

*If it causes ripples in space-time, would space-time be susceptible to forming vortices if massive bodies passed each other at close distances and relativistic speeds?
Sean Carroll raised this possibility, but dismissed it because it was discredited in 2-dimensional space by Gerard 't Hooft.  


*Has anyone investigated if 3-dimensional space would support space-time vortices, and whether such vortices might cause light cones to tilt as if they were caught in a whirlpool, with a tendency toward a timelike loop?


(R.A. Fessenden speculated about gravity waves and vortices in 1913, but he assumed an ether: http://archive.org/stream/jstor-1638835/1638835_djvu.txt.)
I apologize if this question is naive and too wide-ranging.
 A: Is gravitational radiation a form of mass/energy that can form momentum?
We think so. We haven't detected any gravitational waves as yet, but there's a high degree of confidence that gravitational waves are real.
If it causes ripples in space-time, would space-time be susceptible to forming vortices
if massive bodies passed each other at close distances and relativistic speeds?
Again, we think so. But like Fender said, that's to do with gravitomagnetism rather than gravitational waves. See this NASA article:

It starts with this: "Einstein was right again. There is a space-time vortex around Earth, and its shape precisely matches the predictions of Einstein's theory of gravity.
"
Has anyone investigated if 3-dimensional space would support space-time vortices
Yes, see above.
and whether such vortices might cause light cones to tilt as if they were caught in a whirlpool, with a tendency toward a timelike loop?
No. I'm sorry, but while the vortices are bona-fide physics, time machines are mere science fiction. Maxwell talked about vortices.
(R.A. Fessenden speculated about gravity waves and vortices in 1913, but he assumed an ether: https://archive.org/stream/jstor-1638835/1638835_djvu.txt.)
Don't worry about ether. See this and see arXiv for papers with aether in the title. The people who say it's discredited and a dirty word are usually media hacks and celebrity quacks who don't know about GR or Einstein's Leyden Address. That's where he described space as the aether of general relativity.
