I was thinking about planck length and how since it's the smallest unit possible, it'd have to define a universal reference point. Then I went to Wikipedia and found out it's a common misconception and planck length isn't the smallest unit.I should really click this thread more! As a physics student I cried a little reading this. "smallest unit" really doesn't make any sense. You can always go smaller if you had a way to measure that small.
TIL