In 1924, the German mathematician David Hilbert raised a peculiar and seemingly paradoxical question: are some infinities bigger than others? The answer he arrived at – yes, actually – might have been impenetrable to non-mathematicians if not for the thought experiment he devised involving a hotel with an infinite number rooms. This video from the Australian filmmaker and educator Derek Muller builds Hilbert’s ‘infinite hotel’ and populates it with some strange, fuzzy creatures to demonstrate how the mathematician arrived at his groundbreaking conclusion, and touches on the real-world implications of his discovery.