Who cares about topology? (inscribed rectangle problem)

Excellent video for the curious minds! Who cares about Topology such as Torus (aka donut) or Mobius Strip ? They can be used to prove difficult math such as the unsolved problem “Inscribed square/rectangle inside any closed loop”.

To understand the Topology on Loops, please view the lecture  here : Homotopy (同伦) and the Fundamental Group (群) of surface.