I haven't done a ton of research on Gravitational Waves, but I have done some theorizing. Are these properties confirmed (by theory or observation) characteristics of GW?
Gravitational Waves travel at the speed of light
Reasoning: The observation of GW coordinated with the observation of the two black holes colliding. The observations of the collision were Electromagnetic, and inherently traveled at the speed of light (or pretty darn close). If the two sets of waves originated from the same point, and arrived at another point at the same time, then they must be traveling at the same average speed.
Building on #1, Gravitational Waves have no mass
Reasoning: If GW travel at the speed of light, they must have either infinite thrust or zero mass. Infinite thrust is unlikely, therefore we can conclude that they have zero mass.
Also building on #1, the speed of Gravitational Waves can be manipulated
Reasoning: It is well known that the speed of light varies according to the medium through which it travels. Could GW theoretically be slowed down by changing the medium through which they travel? If we could slow them down, would the effects of gravity be lessened, or merely delayed?
Am I correct in my thinking, or have I lost my mind?
Extra Credit: Using what we currently know about GW, could we build a gravity generator? TO CLARIFY: When I say gravity generator, I mean one powerful enough to hold a human to the deck of a spacecraft (not necessarily 1G though - could be as little as 0.1G).