String Theory
A candidate unified theory of all physical forces and particles.

A period of accelerated cosmic expansion early in the history of the universe.

Observable Universe
The sum of all we can see. Also called “our universe.”

Other Universe
An unobserved region of spacetime, perhaps having distinct properties and laws of physics.

Six-dimensional shape of hidden dimensions.

Short for “membrane.” It can be a two-dimensional sheet (like an ordinary membrane) or a lower- or higher-dimensional variant.

A form of energy that fills space like a fog.

Scalar Field
A field described by a single number at every position. Examples: temperature, inflaton field.

Scalar fields that describe the size and shape of hidden space dimensions.

To convert completely to radiation, as happens when matter and antimatter or branes and antibranes collide.