4D (four dimensions) is an important idea in geometry.
Three-dimension space has length, depth and height. The fourth dimension is in relation to that three dimensions like a vertical dimension.
In physics the time is considered as a fourth dimension but in real time people are not allowed to perceive it and it is used for modeling physical and social causes.
In mathematics, four-dimension space is an abstract concept which has been studied by mathematics and philosophers for almost three hundred years.
The mathematicians who studied four-dimension space were Möbius, Schläfi, Bernard Riemann, Charles Howard Hinton, etc.
In twentieth century the concept of spacetime was developed. That connects space and time. The difference is that spacetime is not a Euclidean space but it is called "Minkowski continuum". The four-dimension space was mostly studied in the nineteenth century.
Further reading [change]
- R. Ruyer, Paradoxy vedomi. Praha: PedF UK 1994, str. 78n