general relativity - Gravitational waves and it's interaction with matter

I have been reading an article on gravitational waves here. There, it is written that the gravitational wave, unlike the electromagnetic waves, interact very weakly with matter. The principle of LIGO detectors also support this point.

Question 1: But, if the gravity itself arise due to mass and energy distributions in spacetime, why the ripples in spacetime has a little effect on matter?

I mean, the gravitational radiations are caused by violent cosmic events and hence they should carry enormous energy. But that energy seems to have a little effect on matter. Why is this so? Also, is there any possibility of some entity in spacetime that it could interact with? Do GTR predicts any such entities?

Question 2: Is the spacetime actually a medium for gravitational waves?

I'am asking because the NASA's gravity probe b experiment reveals that the warping of spacetime is a reality. Also, we say that gravitationl waves are ripples in spacetime. The ripples are real. So does the medium too? If yes, is it the same medium which Michelson and Morley searched for (and called as aether)?

Could someone point me in the right direction?

Thanks :)

Answer

Gravity, in general, couples very weakly to matter --- that's why it is often called the 'weakest force'. You can see this by examining the 'coupling constants'---where gravity is $10^{37}$ times weaker than electromagnetism, or comparing how much 'stuff' you need to get equivalent forces---where gravity is about $10^{32}$ times weaker.

Your second question is largely philosophical. But, basically, yes --- spacetime is the medium by which gravity is felt, and the medium through which gravitational waves travel.