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Originally Posted by xelasnave
Thanks for the link Steven I read it all but I think I read it a while back..no matter these days with a failing memory most things seem new☺
Is there any physical nature to a gravity wave and I ask perhaps because of my incomplete understanding of GR...but I see it as a coordinate system describing somewhat movement of space and objects in it with no explaination of the particles involved...I expected ct at some level there must be particles or at least a means of carrying information...I know the eather is not needed but do you see at some level there has to be some form of particle soup that makes up space...You know my passion for a push gravity mechanism☺ but I guess what I ask really is there any view from a quantum level as to what makes up a gravity wave.
I guess I am revisting the idea that a wave must travel in a medium...and I know light is said not to have a mediun so I guess I just cant get my head around how things can move with no medium.
Say take gravity waves essentially a expansion and contraction of space ... what is this medium that expands and contracts..it must be something as it can't be nothing.
I expect what I ask for can only be speculative but I would be happy with that.
Alex
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Alex,
Newton considered space to be nothing more than a coordinate system.
Einstein considered spacetime to be a gravitational ether which is analogous to the old luminiferous ether concept that was once considered the medium in which light propagated.
The gravitational ether allows the propagation of gravitational waves in the form of ripples in spacetime which causes the elongating of spacetime in one direction and contraction in the perpendicular direction.
This elongation and contraction is a very real physical effect and is detected at LIGO and VIRGO which are very sophisticated interferometers as a time delay between a laser beam that travels a slightly further distance in the stretched direction of spacetime than the beam that travels in the contracted direction.
As you are aware spacetime can bend in the presence of mass or expand as in the case of an expanding Universe.
Another property of spacetime if the geometry changes rapidly with time such as in black hole and neutron star mergers or even inflation, gravitational waves are generated.
Gravitational waves carry information in the form of energy.
For example when binary neutron stars merge their combined mass is not the sum of the individual masses but less.
The difference is the energy carried by the gravitational wave.