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 ...

Cepheid variable stars exhibit regular pulsations whose period directly correlates with their intrinsic brightness (absolute luminosity). The Leavitt law establishes this relationship between ...

How should we study biodiversity change? In an ideal world, we would study many different aspects of biodiversity and how they change over time. This would allow us to distinguish between natural ...