How is the universe changing?
Dark energy is basically what triggers the universe into expanding. Many astronomers such as Hubble has proven this and so does Einstein's equations. The universe is expanding at the speed of light, but that doesn't mean it's breaking Einstein's principles. Einstein's explanation for this is that space itself is moving, not something through space. So yeah. Hope that helped.
If that doesn't answer your question, I will become more broad. The universe is dramatically cooling down because of its expansion. Galaxies are getting farther away. In order to better understand this, watch this video .