Nineteenth Arnold Sommerfeld Lecture Series, Two of the most amazing ideas in physics are the holographic

principle and quantum error correction. The holographic principle

asserts that all the information contained in a region of space is

encoded on the boundary of the region, albeit in a highly scrambled

form. Quantum error correction is the foundation of our hope that

large-scale quantum computer can be operated to solve hard

problems. I will argue that these two ideas are closely related, and

will describe quantum codes which realize the holographic

principle. These codes provide simplified models of quantum

spacetime, opening new directions in the study of quantum gravity,

though many questions remain.