Skip to main content

How big is infinity? - Dennis Wildfogel

3,550,633 Views

22,232 Questions Answered

TEDEd Animation

Let’s Begin…

Using the fundamentals of set theory, explore the mind-bending concept of the “infinity of infinities” -- and how it led mathematicians to conclude that math itself contains unanswerable questions.

Infinity plus one. In a magical town in a far away land, the only place where visitors can stay is The Infinite Hotel. This hotel has rooms numbered 1, 2, 3, and so on, one room for each positive whole number. One day, a mathematician on vacation showed up at the Infinite Hotel and asked for a room. “I’m sorry,” said the proprietor, “all the rooms are taken.” “That’s no problem,” said the mathematician. “You can still free up a room for me.” He then explained to the proprietor what to do. “Oh, I see!” exclaimed the proprietor. “Very clever! We’ll do that and then put you in the empty room.” What did the mathematician tell the proprietor to do?

Sign in to answer question

About TED-Ed Animations

TED-Ed Animations feature the words and ideas of educators brought to life by professional animators. Are you an educator or animator interested in creating a TED-Ed Animation? Nominate yourself here »

Meet The Creators

  • Director Aaron Augenblick
  • Educator Dennis Wildfogel
  • Animator Hal Lee
  • Producer Lisa Thomas
  • Narrator Dennis Wildfogel

More from Math In Real Life