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.