What we don't know about the cosmos can fill volumes. Today is about contemplating whether or not extraterrestrial intelligent life exists.

https://www.britannica.com/story/the-fermi-paradox-where-are-all-the-aliens

https://www.britannica.com/science/Drake-equation

https://www.astronomy.com/news/2020/11/the-great-filter-a-possible-solution-to-the-fermi-paradox

https://exoplanets.nasa.gov/search-for-life/are-we-alone/