Tie a trefoil knot in a piece of string, seal the ends together, and try to wiggle it free without cutting. In three-dimensional space, the knot holds firm. Add a fourth spatial dimension, however, ...

Theoretically, it’s impossible for us to perceive a 4D creature. That is, unless it broke into our three-dimensional reality.

Zsuzsanna Dancso does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond ...