# physics

## Table of Contents

## 1. Laws of Nature

By engaging in physics modeling, we are postulating that there are rules that "nature" follows, and that these rules are logically consistent. At least, mathematical models postulate this, and non-mathematical models of the universe have been relegated to the study of metaphysics.

## 2. Fields in Physics

The current challenge in physics is uniting the big and the small; general relativity, and quantum mechanics. There is no currently known theory that can describe everything, and the very nature of this problem is one containing many correspondences and dualities.

### 2.1. Classical Mechanics

Classical mechanics deals with fields of physics that do not deal with time dilation or quantum weirdness. It is called classical mechanics because most of these theories were invented before their quantum or relativistic counterparts, and usually serve as a baseline understanding for the later topics.

#### 2.1.1. Newtonian mechanics

It all started when Newton created three (but really two) fundamental laws of the universe that governed all things.

#### 2.1.2. Lagrangian mechanics

This is a different strain of classical mechanics. Instead of looking at direction and vectors, it looks at a single fundamental principle, even more fundamental than inertia and conservation of momentum: optimization. We believe that nature always optimizes for some parameters in all physical phenomena. Almost all physical theories including electromagnetism, general relativity, Newtonian mechanics, and even quantum mechanics can be explained within the Lagrangian framework.

#### 2.1.3. Fluid Mechanics

#### 2.1.4. Thermodynamics

#### 2.1.5. Classical Electrodynamics

Classical electrodynamics attempts to explain the electromagnetic force from a classical perspective. What is light? How does electricity actually work? All these questions you will find (half) answered in the study of electrodynamics, giving rise to the complete theory encoded in Maxwell's Equations.

#### 2.1.6. General Relativity

General Relativity aims unify gravity with , in a unified theory of macroscopic forces including classical electromagnetism.

### 2.2. Quantum Mechanics

Quantum mechanics renounces all hope of having a deterministic view of physics, and instead replaces direct causation with statistical causation, at least according to some interpretations.

### 2.3. QFT

Quantum Field Theory is an approach that combines with quantum mechanics, then utilizing a process called canonical quantization in order to quantize a given field. This is the closest thing we have to a theory of everything in physics.

## 3. Note

I did not exhaustively cover all fields in physics but this is most of it.