Euler’s identity is a mathematical beauty that ties five fundamental mathematical constants in mathematics together. In the equation, we have *e*, the base of natural logarithms, *i,* the imaginary unit, *π, *the ratio of the circumference of a circle to its diameter. This identity shows a profound connection between the most fundamental numbers in mathematics.

## Boltzmann’s Constant

The fundamental constant of physics, the Boltzmann constant, is one of the seven "defining constants" that have been given exact definitions.