The Universe
The universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy.
Gravitational lensing has been used for the first time to detect and measure an inactive black hole. The door is now open to study the largest black holes in the universe. "Gravitational lensing events are rare, but are most prevalent in the most massive galaxies, that host the largest black holes."