Introduction to Physics

• Physics is a natural science examining matter, its fundamental components, motion, behavior through space-time, and related energy and force entities.
• As a foundational scientific discipline, physics seeks to understand the universe's behavior.
• The scientific method underpins physics through the formulation and testing of hypotheses based on observation.
• Physics develops physical theories to describe and predict natural phenomena through mathematical expressions.

Classical Mechanics

• Classical mechanics accurately describes the motion of macroscopic objects, ranging from projectiles to spacecraft, when objects are large enough to be measured and speeds are much slower than light.
• This branch of physics relies on Isaac Newton's laws of motion that relate a body to forces acting upon it; also included is the law of universal gravitation.

Thermodynamics

• Thermodynamics studies heat, temperature, and their relationship to energy and work, focusing on energy transfer between places and forms.
• Key concepts include:
  • System: The specific portion of the universe under analysis.
  • Surroundings: Everything external to the defined system.
  • Heat: Energy exchange between a system and its surroundings due to temperature differences.
  • Work: Energy transfer caused by a force inducing displacement.
  • Internal Energy: The total energy contained within a system.
  • Temperature: A measurement of the average kinetic energy of a system's particles.
  • Entropy: A measure of disorder within a system.
• Thermodynamics operates under these laws:
  • Zeroth Law: Systems in thermal equilibrium with a third system are also in equilibrium with each other.
  • First Law: Energy is conserved; it transforms rather than being created or destroyed.
  • Second Law: The total entropy of an isolated closed system can only increase.
  • Third Law: As temperature nears absolute zero, a system's entropy approaches a minimum or zero value.

Electromagnetism

• Electromagnetism explores the forces between electrically charged particles.
• This field encompasses:
  • Electrostatics: The study of stationary electric charges.
  • Electrodynamics: The study of moving electric charges and their interplay with magnetic fields.
  • Magnetostatics: The study of static magnetic fields.
• Core concepts:
  • Electric Charge: A fundamental property causing matter to experience force in an electromagnetic field.
  • Electric Field: The spatial region around a charged particle or object where electric force acts on other charges.
  • Magnetic Field: Force fields generated by moving electric charges.
  • Electromagnetic Waves: Oscillating electric and magnetic fields propagating through space and carrying energy.
• Maxwell's equations detail how electric charges and currents generate electric and magnetic fields, and how these fields propagate as electromagnetic waves.

Optics

• Optics examines light's behavior and properties, including its interaction with matter. It also deals with the construction of instruments that utilize or detect light, typically visible, ultraviolet, and infrared.
• Key optical concepts:
  • Reflection: Wavefront redirection at the interface of two media, causing it to return to its origin medium.
  • Refraction: Wave direction change as it passes between media, influenced by speed variation.
  • Diffraction: The bending of waves around obstacles or via openings.
  • Interference: The superposition of waves, resulting in either reinforcement or cancellation of displacement.
  • Polarization: Confinement of light wave vibrations to a single plane.

Quantum Mechanics

• Quantum mechanics, or quantum physics/theory, explains nature's properties at the atomic and subatomic levels with probabilistic mathematical descriptions.
• This provides:
  • Descriptions of matter's properties on an atomic scale.
  • A theory of radiation.
• Accounting for relationships between matter and radiation.
• Key concepts:
  • Quantization: Physical quantities exist only in discrete amounts.
  • Wave-Particle Duality: Every quantum entity can be described as both a particle and a wave.
  • Uncertainty Principle: Limits exist on the precision with which position and momentum of a particle can be simultaneously known (Heisenberg's principle).
  • Superposition: Quantum entities exist in multiple states at once.
  • Quantum Entanglement: Linked quantum particles instantaneously affect each other regardless of distance.

Relativity

• Relativity, primarily associated with Albert Einstein, consists of special and general theories.
• Special relativity applies to all physical phenomena except gravity.
• General relativity explains gravitation and its relation to other natural forces.
• Key concepts of special relativity:
  • Physical laws are consistent for all observers in uniform motion.
  • Vacuum light speed is constant for all observers.
  • Time dilation: Time slows for moving objects relative to stationary observers.
  • Length contraction: Moving object length appears shorter in motion direction.
  • Mass-energy equivalence: E=mc^2 describes interchangeability of energy and mass.
• Key ideas in general relativity:
  • Gravity is spacetime curvature caused by mass and energy, not just a force.
  • Massive objects warp spacetime, affecting the paths of other objects.
  • Gravitational time dilation: Time slows in stronger gravitational fields.
  • Black holes: Spacetime regions with gravity so intense that nothing escapes.

Nuclear Physics

• Nuclear physics studies the components and interactions within atomic nuclei and other forms of nuclear matter,closely related to atomic physics but distinct as it focuses on the nucleus rather than the entire atom.
• This field's discoveries have broad applications:
  • Nuclear power and weapons
  • Nuclear medicine
  • Magnetic resonance imaging
  • Industrial/agricultural isotopes
  • Ion implantation
  • Radiocarbon dating
• Key concepts include:
  • Nucleons: Protons and neutrons in atomic nuclei.
  • Isotopes: Variants of elements with different neutron counts.
  • Nuclear Force: Binds protons and neutrons in the nucleus.
  • Radioactivity: Unstable nuclei decay and emit particles/energy.
  • Nuclear Reactions: Reactions involving atomic nuclei like fission and fusion.

Condensed Matter Physics

• Condensed matter physics studies macroscopic and microscopic properties of matter, including phase transitions, structure, and mechanical, electromagnetic, and thermal behaviors.
• Concentrating on "condensed" phases with numerous constituents and strong interactions, familiar examples are solids and liquids; exotic phases include superconductors, ferromagnetic/antiferromagnetic materials, and Bose-Einstein condensates.
• The phases' behaviors are understood using physics laws.
• Key concepts:
  • Crystal Structure: Atomic arrangement in solids.
  • Electronic Band Structure: Electron energy ranges within a solid.
  • Phonons: Collective atomic vibration modes in solids.
  • Superconductivity: Zero electrical resistance below a critical temperature.
  • Magnetism: Material properties related to attraction/repulsion by magnetic fields.