You probably know the basics when it comes to black holes: A lot of mass squished into not a lot of volume makes for an entity so prodigiously dense, not even light can escape its gravity. Perhaps you even know about things like event horizons, the boundary outside of which escape becomes possible, and gravitational waves, the ripples that black holes generate in the cosmic fabric when they collide. Conceivably you even know what a black hole would “look” like, if you were ever so fortunate (unfortunate?) as to observe one up close: a gyre of oddly lit matter that wraps around a spherical split in spacetime, thanks to the beam-bending effects of gravitational lensing (another essential black hole concept).

Maybe you already know all of these things. For all I know, you’re the champ of black hole trivia. But at some point, your knowledge probably peters out and collapses in on itself like a … like a … well, like a something. That simile got away from me. But! Fortunately! Wherever and whenever your command of the subject craps out, Varoujan Gorjian will be there to pick up where you left off.

A research astronomer at NASA’s Jet Propulsion Laboratory, Grojian specializes in—and I’d just like to pause here to emphasize that this is the official title of his research group at JPL—the structure of the universe. Which means the guy not only knows about event horizons and gravitational lensing but stuff like tidal forces (what!), x-ray binaries (hey now!), and active galactic nuclei (oh my god!). Seriously, the guy’s knowledge of black holes is encyclopedic.

And best of all, he’s good at explaining the stuff. Check out the video above to watch Gorjian discuss black holes at five scales of difficulty, from grade school to grad school right on up to fellow-black-hole-expert levels. Because who among us doesn’t want to hear two authorities on the subject nerd out about the extracoronal illumination of accretion disks? (There. Bet you didn’t know that term.)