From the June 2010 issue

If all the known matter in the universe were compressed into one colossal black hole, how big would it be (both size and mass)?

Mickey Haney, Redondo Beach, California
By | Published: June 28, 2010 | Last updated on May 18, 2023
Rogue black hole
This artist’s conception shows a black hole floating near a globular star cluster.
David A. Aguilar (CfA)

… total mass of about 10 billion trillion times our Sun’s mass. A black hole of that mass would itself have a size of billions of light-years.