Is it possible to make a gravity mirror ?

1. Jan 28, 2010

pef

is it possible to make a "gravity mirror"?

Does anyone out there know if under today's accepted laws of physics it would be possible for something to exist that could reflect gravity?.
The reason I ask is because I am a bit of a late starter with this physics thing. I did schoolboy physics when I was young but got no further education on the subject.
Over the last couple of years I have become interested enough to read quite a few books on various physics subjects published for the general public. This means my understanding of the subjects might be a bit skewed.
The trouble with books is you can't ask them a straight question.
I suppose my question is really about the relationship between mass, inertia and gravity.

Could you theoretically insulate an object from gravitational effects? And if so would this have any bearing on its mass or inertia?
This is my first posting on this site so please don't shout too loud if my question is stupid.
But if it is stupid then a layman's explanation of why would be very much appreciated.

2. Jan 28, 2010

torquil

Re: is it possible to make a "gravity mirror"?

I would say the following is the current state of physics regarding this matter:

Gravity affects all objects with non-zero energy. These objects will move on geodesics. There is no known object that does not do this. So all objects are affected by gravity. So I don't think it is possible with todays physics to create any kind of anti-gravity device :-)

Regarding the mirror idea: GR predicts gravitational waves. Similarly to electromagnetical waves, these will affect any particle, and shake it around. The shaking particle can produce its own gravitational wave. So in principle, I see no reason why a gravitational mirror cannot be made. The secondary gravitational wave from each constituent particle in the "mirror" would have to combine to form a coherent gravitational wave that is reflected back on the opposite direction. This doesn't mean that the mirror is not affected by the incoming gravitational wave. It only means that some of the incoming wave is reflected back.

Have a look at this for some speculation:
http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=2207

Quote:
"This is the basis on which a gravitational wave can interact with a superconducting sheet. “Quantum delocalization causes the Cooper pairs of a superconductor to undergo non-geodesic motion relative to the geodesic motion of its ionic lattice,” says Chiao and buddies.

They speculate that this difference in motion causes the sheet to absorb energy from the gravitational wave and then re-radiate it as gravitational wave travelling in the opposite direction–in other words specular reflection."

Torquil