- Classical mechanics: Basically views time as another spacial axis. In classical mechanics bodies can be viewed as being a 4D extrusion of their 3D shape along a 1D time path. High precision simulation of classical mechanics does not model time as steps / frames in a movie, but as a continuous 4D geometry.
- Relativity: Builds on classical mechanics idea that time is a geometric axis and using a 4D coordinate system. What is further added is the possible distortion of that 4D spacetime.
- Quantum mechanics: Strictly speaking quantum mechanics does not model time at all. It is more like algebra. It only describes equivalences / transformations which can occur. When we reformulate some algebraic expressions we don't think of the steps we take as time steps. It wouldn't work anyway because there are many possible paths not one. It is not a 1D sequence but a graph, which can even contain cycles.
- Thermodynamics: None of the other areas of physics make time "pass", because to them time is symmetric and past and future might as well be swapped. Only thermodynamics introduces an asymmetry by coupling it to information theory: On the macroscopic average, entropy can not decrease, only increase. Thus, we get a global gradient form low to high entropy, which is what makes time irreversible on a large scale.
- Relativity: Builds on classical mechanics idea that time is a geometric axis and using a 4D coordinate system. What is further added is the possible distortion of that 4D spacetime.
- Quantum mechanics: Strictly speaking quantum mechanics does not model time at all. It is more like algebra. It only describes equivalences / transformations which can occur. When we reformulate some algebraic expressions we don't think of the steps we take as time steps. It wouldn't work anyway because there are many possible paths not one. It is not a 1D sequence but a graph, which can even contain cycles.
- Thermodynamics: None of the other areas of physics make time "pass", because to them time is symmetric and past and future might as well be swapped. Only thermodynamics introduces an asymmetry by coupling it to information theory: On the macroscopic average, entropy can not decrease, only increase. Thus, we get a global gradient form low to high entropy, which is what makes time irreversible on a large scale.