String Theory For Dummies, 2nd Edition

Chapter 13

Gaining Insights from the Holographic Principle

IN THIS CHAPTER

Looking at optical holograms

Using holograms to peer inside black holes

The holographic principle and the boundary of the universe

Another key insight into string theory comes from the holographic principle, which relates a theory in space to a theory defined only on the boundary of that space. Many physicists believe that the holographic principle should hold in any sensible quantum gravity theory, and indeed, it was first formulated without any reference to string theory. But it is in string theory that holography can be really made precise.

In this chapter, we look at what makes holograms so special and how they can be used to encode information in fewer dimensions. We see how the holographic principle can be applied to the study of black holes. Finally, we consider how the idea of holograms has been applied to string theory.

What’s a Hologram?

Most people have experienced holograms as images (often on stickers and sometimes on posters) that seemingly morph into different images depending on the viewing angle. The image subtly shifts when you view it from different perspectives so that it (kind of) looks ...