Think of the universe as a painting. There’s the image made in paint, and the surface it was painted on. The canvas.
The stars, the planets, the gasses, the matter and energy and even the space between are the paint. What’s the canvas? Is there a canvas? Would the canvas follow the same rules as the paint?
That is the key to almost everything. Quantum mechanics is neat and tidy. Space time is neat and tidy. They don’t play well with each other, though. Some scientists say that we need to figure out dark matter and dark energy to make them play together. Others say they are so incompatible that we need new science altogether to figure it out.