In the late 1990s, theoretical physicists uncovered a remarkable connection between two seemingly unrelated concepts in theoretical physics. That connection is almost inscrutably technical, but it might have far-reaching consequences for our understanding of gravity and even the universe.
To illustrate this connection, we’re going to start at — of all places — a black hole. Researchers have found that when a single bit of information enters a black hole, its surface area increases by a very precise amount: the square of the Planck length (equal to an incredibly small 1.6 x 10^-35 meters on a side).
At first blush, it may not seem all that interesting that a black hole gets larger when matter or energy falls into it, but the surprise here is that it’s the surface area, not the volume, that grows in direct proportion to the infalling information, which is totally unlike most other known object in the universe. For most objects that we’re familiar with, if it “consumes” one bit of information, its volume will grow by one unit, and its surface area by a only a fraction. But with black holes, the situation is reversed. It’s like that information isn’t inside the black hole, but instead stuck to its surface.