you know what you don't know:

"It's embarrassing, but astrophysicists are the first to admit it. Our best theoretical model can only explain 5% of the universe. The remaining 95% is famously made up almost entirely of invisible, unknown material dubbed dark energy and dark matter. So even though there are a billion trillion stars in the observable universe, they are actually extremely rare."

Read more at: https://phys.org/news/2018-12-bizarre-dark-fluid-negative-mass.html#jCp
https://phys.org/news/2018-12-bizarre-dark-fluid-negative-mass.html