They are, but not in the same way. Look up "black hole" on wikipedia, you get serendipitous info on particles, spacetime, gravitation, etc. If you look it up in

They are, but not in the same way. Look up "black hole" on wikipedia, you get serendipitous info on particles, spacetime, gravitation, etc. If you look it up in the Library of Congress, you get: "A stars, Asymptotic giant branch stars, B stars, Be stars, Black holes, Blue stragglers, Brightest stars, Brown dwarfs, Cool stars, Delta Scuti stars, Dwarf novae, Dwarf stars, and Early stars." I think the second set of results is a more useful serendipidy. https://catalog.loc.gov/vwebv/holdingsInfo?searchId=9410&recCount=25&recPointer=1&bibId=1196872 https://catalog.loc.gov/vwebv/holdingsInfo?searchId=9410&rec... https://www.loc.gov/aba/publications/FreeLCC/Q-outline.pdf https://www.loc.gov/aba/publications/FreeLCC/Q-outline.pdf