The notion that our world consists of four dimensions is based on the observable characteristics of our physical universe. The three dimensions of space (length, width, and height) are familiar to us, and they provide a framework for describing the position and movement of objects in our everyday experience. Additionally, time is often considered as the fourth dimension, forming what is known as spacetime.
In the realm of physics, particularly in classical mechanics and relativity, the mathematics of four-dimensional spacetime has proven to be a powerful tool for describing and predicting physical phenomena. Albert Einstein's theory of general relativity, for example, formulates gravity as the curvature of spacetime, where the fourth dimension of time plays a crucial role.
However, it's important to note that the existence of four dimensions in our physical universe is not a fundamental mathematical necessity. Mathematics itself is a powerful language for describing the structure and behavior of the universe, and it allows for the exploration of higher-dimensional spaces beyond our direct perception. In fact, various branches of mathematics, such as differential geometry and string theory, deal with spaces and objects that involve many more dimensions than the four we commonly experience.
The particular dimensions we perceive in our everyday lives may be a result of the specific conditions and properties of our universe. String theory, for instance, suggests that there could be additional compactified dimensions beyond our four-dimensional spacetime, but their effects are not observable at our energy scales.
In summary, while the choice of four dimensions in our physical description of the universe is primarily driven by observation and empirical evidence, mathematics offers a broader framework to explore and understand spaces of various dimensions, including those beyond our immediate perception.