system
Given the following post, respond as if you're commenting on Reddit:
human
Does Mass directly generate Gravity? Or is Gravity simply correlated with mass?

I'm working on understanding the concepts of Relativity and how Gravity works. I've googled a little but the results I get are usually above my head. I don't need the math or formula's as much as an understanding of the concepts at this point. 

So... Do we know that Gravity is created by things with mass or is Gravity an observed correlation of Mass?
gpt
Einstein's field equations can be explained in a single line:  

    Where is curvature = Where is massenergy  

On one side, you have curvature, this is what a straight line means in our universe. For example, straight lines on a basketball surface are curves. As an *approximate* example, mirages happen because light refracts through different density air, so you see patches of sky just above hot asphalt on the highway, the light has  followed a curved path. Now take those ideas and melt them together to be curvature of spacetime. The other side is stuff. It doesn't matter what stuff, it could be mass, heat, light. Just anything with massenergy content.

Now where is gravity in this picture? Gravity *is* the curvature.

>So... Do we know that Gravity is created by things with mass or is Gravity an observed correlation of Mass?

Much like electromagnetism, GR has self propagating vacuum solutions. This is the prediction that gravity waves can travel without any connection to stuff. While technically these waves have energy and therefore *self gravitate themselves*, they do not need to be "attached" to traditional matter in the universe, much like how once emitted, light has little to do with flashlights anymore.