David Kaplan explores one of the biggest mysteries in physics: the apparent contradiction between general relativity and quantum mechanics. QUANTA MAGAZINE Website: https://www.quantamagazine.org/ Facebook: https://www.facebook.com/QuantaNews Twitter: https://twitter.com/QuantaMagazine You can also sign up for our weekly newsletter: http://eepurl.com/6FnWj. David Kaplan is a theoretical particle physicist at Johns Hopkins University and a producer of the award-winning documentary Particle Fever. Filming by Petr Stepanek. Editing and motion graphics by MK12. Music by Steven Gutheinz. Quanta Magazine is an editorially independent publication launched by the Simons Foundation. More about quantum gravity: https://www.quantamagazine.org/tag/quantum-gravity/