Index
Space & Time
In physics, spacetime, also called the space-time continuum, is a mathematical model that fuses the three dimensions of space and the one dimension of time into a single four-dimensional continuum. Spacetime diagrams are useful in visualizing and understanding relativistic effects, such as how different observers perceive where and when events occur.
Until the turn of the 20th century, the assumption had been that the three-dimensional geometry of the universe (its description in terms of locations, shapes, distances, and directions) was distinct from time (the measurement of when events occur within the universe). However, space and time took on new meanings with the Lorentz transformation and special theory of relativity.
In 1908, Hermann Minkowski presented a geometric interpretation of special relativity that fused time and the three spatial dimensions into a single four-dimensional continuum now known as Minkowski space. This interpretation proved vital to the general theory of relativity, wherein spacetime is curved by mass and energy.
Quantum Mechanics & General Relativity
Quantum mechanics and general relativity are two fundamental theories in physics that describe different scales of the universe, with quantum mechanics governing the behavior of very small particles and general relativity explaining gravity on large cosmic scales; however, they are currently incompatible with each other, meaning they cannot be seamlessly combined to explain phenomena where both very small scales and strong gravity are involved, like inside a black hole, due to their different conceptual frameworks regarding space, time, and the nature of physical events.