Lagrange wrote in his Mécanique analytique (published 1788, based on work done around 1755) that mechanics can … See more

Mathematically, a four-dimensional space is a space that needs four parameters to specify a point in it. For example, a general point might have position vector a, equal to
This can be written in terms of the four standard b… See more

In the familiar three-dimensional space of daily life, there are three coordinate axes—usually labeled x, y, and z—with each axis orthogonal (i.e. perpendicular) to the other two. The six cardinal directions in this space can … See more