I Visited the First Gravitational Wave Detector! LIGO | STELLAR

Just curious, but if gravitational waves have such a low interaction with matter, how is it that they can be claimed to be detected many years after the fact of their generation.  If you look at any wave, it interacts with matter, the more the interaction, the stronger the wave.  The less interaction, the less strength the wave has, and it diffuses into less and less energy as it travels from the source (entropy). Thus gravitational waves should diffuse into null energy within micro, nano or pico seconds, not years (on any scale). 

The second half of my wondering is why is it that a gravitational wave which is supposed to be radiation is able to travel all the way through space, and our atmosphere, unhindered so that we can detect it with all the chaos continuously happening on our planet.


And... if it is radiation, 'how in the universe' is radiation supposed to cause matter to attract other matter.  It is repulsive by nature. It is energy coming out of matter, not going into it.  Someone correct my thinking.  I'm obviously missing some pieces of the puzzle here.