The number [math]\pi[/math] (/'pai/; Greek: [pi]) is a mathematical constant that is equal to the ratio of a circle's circumference to its diameter, approximately 3.14159. read more
[math]\pi[/math] is probably the most ubiquitous mathematical constant. Since mathematics is the language of physics, it is not surprising to see a lot of [math]\pi[/math] in mechanics, electromagnetism, thermodynamics, cosmology, and perhaps all branches of physics. read more
Pi also appears in the physics that describes waves, such as ripples of light and sound. It even enters into the equation that defines how precisely we can know the state of the universe, known as Heisenberg's uncertainty principle. Finally, pi emerges in the shapes of rivers. read more