This video from Vsauce discusses cardinal numbers, the cardinality of the natural numbers (aleph null), ordinal numbers, and all sorts of infinities.
This video from Veritasium discusses the expansion of the Universe, the Hubble sphere, and the possibility of an infinite Universe.
What’s the point of learning secant, cosecant, and cotangent, if they’re just the inverses of cosine, sine, and tangent? Do they have any purpose other than confusing students?
This quick video by Veritasium conceptually explains Heisenberg’s uncertainty principle and how it relates to the single-slit experiment.
Also, why can’t you get a suntan through a window?