Introduction to Physics

• Physics is a natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force.
• Physics is one of the most fundamental scientific disciplines, and its main goal is to understand how the universe behaves.

Core Concepts

• Mechanics: Deals with the motion of objects and the forces that cause that motion
• Thermodynamics: Deals with heat, work, and energy, and the relationships between them
• Electromagnetism: Deals with the forces that occur between electrically charged particles
• Optics: The study of light and its behavior
• Quantum mechanics: Deals with the behavior of matter at the atomic and subatomic levels
• Relativity: Deals with the relationship between space and time
• Nuclear physics: Deals with the structure, properties, and reactions of atomic nuclei
• Particle physics: Deals with the fundamental constituents of matter and their interactions
• Condensed matter physics: Deals with the macroscopic and microscopic physical properties of matter

Mechanics

• Kinematics: Describes the motion of objects without considering the forces that cause the motion
• Deals with displacement, velocity, and acceleration
• Dynamics: Deals with the forces that cause motion
• Newton's laws of motion:
• First law: An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by a force
• Second law: The acceleration of an object is directly proportional to the net force acting on the object, is in the same direction as the net force, and is inversely proportional to the mass of the object (F = ma)
• Third law: For every action, there is an equal and opposite reaction
• Work: The energy transferred to or from an object by means of a force acting on the object
• Energy: The ability to do work
• Kinetic energy: The energy of motion
• Potential energy: The energy of position

Thermodynamics

• Temperature: A measure of the average kinetic energy of the particles in a system
• Heat: The transfer of energy between objects or systems due to a temperature difference
• Laws of thermodynamics:
• Zeroth law: If two systems are each in thermal equilibrium with a third system, then they are in thermal equilibrium with each other
• First law: Energy cannot be created or destroyed, only transformed from one form to another
• Second law: The entropy of an isolated system always increases
• Third law: The entropy of a system approaches a constant value as the temperature approaches absolute zero
• Entropy: A measure of the disorder of a system
• Heat transfer: Conduction, convection, and radiation

Electromagnetism

• Electric charge: A fundamental property of matter that causes it to experience a force when placed in an electromagnetic field
• Electric field: A field of force surrounding an electric charge
• Electric potential: The amount of work needed to move a unit of electric charge from a reference point to a specific point in an electric field
• Electric current: The rate of flow of electric charge
• Magnetism: A force that arises due to the motion of electric charges
• Magnetic field: A field of force surrounding a magnetic material or a moving electric charge
• Electromagnetic induction: The production of an electromotive force (emf) across an electrical conductor in a changing magnetic field
• Maxwell's equations: A set of four equations that describe the behavior of electric and magnetic fields

Optics

• Light: Electromagnetic radiation that is visible to the human eye
• Reflection: The change in direction of a wave at an interface between two different media
• Refraction: The change in direction of a wave as it passes from one medium to another
• Lenses: A transparent object that refracts light
• Interference: The superposition of two or more waves, resulting in a new wave pattern
• Diffraction: The bending of waves around obstacles or through openings
• Polarization: The restriction of the vibrations of a transverse wave to one direction

Quantum Mechanics

• Quantum: The minimum amount of any physical property that can exist in an interaction
• Wave-particle duality: The concept that every elementary particle or quantum entity exhibits the properties of both particles and waves
• Uncertainty principle: States a fundamental limit to the precision with which certain pairs of physical properties of a particle, such as position and momentum, can be known simultaneously
• Quantum entanglement: A quantum mechanical phenomenon in which the quantum states of two or more objects are linked together
• Quantum field theory: A theoretical framework that combines quantum mechanics with special relativity to describe the behavior of subatomic particles

Relativity

• Special relativity: Deals with the relationship between space and time for observers moving at constant velocities
• Postulates:
• The laws of physics are the same for all observers in uniform motion relative to one another
• The speed of light in a vacuum is the same for all observers, regardless of the motion of the light source
• Time dilation: The slowing down of time for an observer who is in motion relative to another observer
• Length contraction: The shortening of an object in the direction of motion as its speed approaches the speed of light
• Mass increase: The increase in the mass of an object as its speed approaches the speed of light
• Mass-energy equivalence: Energy equals mass times the speed of light squared (E=mc^2)
• General relativity: Deals with the relationship between gravity, space, and time
• Gravity: The curvature of spacetime caused by mass and energy
• Black holes: Regions of spacetime where gravity is so strong that nothing, not even light, can escape

Nuclear and Particle Physics

• Atomic nucleus: The positively charged central core of an atom, consisting of protons and neutrons
• Nuclear force: The force that holds protons and neutrons together in the nucleus
• Radioactivity: The spontaneous emission of particles or energy from an unstable atomic nucleus
• Nuclear reactions: A process in which two nuclei, or a nucleus and an external particle, collide to produce one or more new nuclei and/or particles
• Elementary particles: The fundamental constituents of matter
• Quarks: Elementary particles that are the building blocks of protons and neutrons
• Leptons: Elementary particles that include electrons and neutrinos
• Bosons: Force-carrying particles

Condensed Matter Physics

• Deals with the macroscopic and microscopic physical properties of matter
• Phases of matter: Solid, liquid, gas, and plasma
• Crystalline solids: Solids with a regular, repeating arrangement of atoms
• Amorphous solids: Solids with a random arrangement of atoms
• Superconductivity: A phenomenon in which certain materials exhibit zero electrical resistance below a critical temperature
• Magnetism: A force that arises due to the motion of electric charges
• Semiconductors: Materials with electrical conductivity between that of a conductor and an insulator