Our intuition about states of matter comes from our experience on Earth's surface, where the pressure is uniformly low and variations in temperature cause changes in the state of matter from solid to liquid to gas. Therefore, when we think of melting or boiling or the creation of plasma, we intuitively assume it reflects an increase in temperature. This bias comes from the fact that we live in a very constant pressure environment. Even small changes in pressure, such as those we experience when under water or on high mountaintops, can have very large effects on our metabolism. But the pressure changes we experience are trivial compared to the pressure range of the overall planetary environment. Since pressure is controlled by the weight of overlying material, pressures increase rapidly with depth. Imagine the pressures generated by the weight of rock a mile thick! For this reason a planet's pressure ranges are enormous ─ from essentially zero pressure in space to pressures of millions of atmospheres in planetary interiors.