In science, a variable is something that can be changed, measured or controlled in an experiment. Scientists look at variables to understand how they affect things. A variable is any one of the things ...

A variable star is, quite simply, a star that changes brightness. A star is considered variable if its apparent magnitude (brightness) is altered in any way from our perspective on Earth. These ...

Suppose you are about to meet a person for the first time and want to predict that person’s thoughts, feelings, and behaviors in a variety of settings over the next several years. What single piece of ...