Quantum Mechanics: Exploring the Subatomic World

• Physics is a natural science examining matter, its motion, and behavior through space and time, including the study of energy and force.
• It stands as one of the most foundational scientific disciplines.
• The central aim of physics involves understanding the behavior of the universe.
• The scientific method is employed in physics for testing and refining theories.
• Physics encompasses various branches, such as classical mechanics, electromagnetism, thermodynamics, and quantum mechanics.

Quantum Mechanics

• Quantum mechanics is a fundamental theory describing physical properties at the atomic and subatomic scales.
• Referred to as quantum physics or quantum theory.
• It addresses physical phenomena at microscopic scales, where action is on the order of the Planck constant.
• It diverges from classical mechanics at atomic and subatomic levels.
• Quantum mechanics integrates quantization, wave-particle duality, the uncertainty principle, and probabilistic interpretations.
• Key concepts:
  • Quantization: Energy, momentum, angular momentum, and quantities are often restricted to discrete values.
  • Wave-particle duality: Particles can display wave-like properties, and waves can act as particles.
  • Uncertainty principle: There are fundamental precision limits concerning certain paired physical properties of a particle, like position and momentum, which can be known simultaneously.
  • Superposition: A quantum system can exist in multiple states simultaneously until measured.
  • Entanglement: Multiple quantum systems become linked, sharing the same fate regardless of distance.

Electromagnetism

• Electromagnetism explores the electromagnetic force, one of the four fundamental forces.
• It is the force between electrically charged particles.
• It includes electricity and magnetism as interconnected aspects of a single phenomenon.
• It explains interactions of charged particles and encompasses electric and magnetic field studies.
• Classical electromagnetism relies on Maxwell's equations, detailing electric and magnetic field behavior and their interactions with matter.
• Key concepts and laws:
  • Electric charge: A property causing matter to experience force in an electromagnetic field.
  • Electric field: A vector field describing electric force exerted on a unit positive charge.
  • Magnetic field: A vector field describing magnetic force exerted on a moving electric charge.
  • Electromagnetic waves: Propagating oscillating electric and magnetic fields, including light, radio waves, and X-rays.
  • Lorentz force: The force on a charged particle moving in an electromagnetic field.
  • Faraday's law of induction: A changing magnetic field induces an electromotive force (EMF) or voltage in a circuit.
  • Ampère's law: Electric currents generate magnetic fields.
  • Maxwell's equations: Four equations describing electric and magnetic field behavior.

Relativity

• Relativity, proposed by Albert Einstein in 1905, elucidates the structure of space and time and their relationship with matter and energy.
• Divided into special and general relativity.
• Special relativity addresses the connection between space and time for observers in uniform motion.
• General relativity concerns gravity and its relation to spacetime structure.
• Key concepts of special relativity:
  • Laws of physics remain consistent for all observers in uniform motion.
  • Speed of light in a vacuum is constant for all observers, regardless of light source motion.
  • Time dilation: Time slows down for moving observers relative to stationary ones.
  • Length contraction: The length of an object shortens in the direction of motion relative to the observer.
  • Mass-energy equivalence: Energy and mass are interchangeable, as shown by E=mc^2.
• Key concepts of general relativity:
  • Gravity is the curvature of spacetime caused by mass and energy, rather than a force.
  • Spacetime curvature determines object movement.
  • Gravitational time dilation: Time passes more slowly in stronger gravitational fields.
  • Black holes: Spacetime regions with gravity so strong that nothing, even light, can escape.
  • Gravitational waves: Ripples in spacetime caused by accelerating massive objects.

Thermodynamics

• Thermodynamics explores heat, work, energy, and their interrelations.
• It deals with bulk properties of matter and energy transfers in physical systems.
• It is based on fundamental laws governing energy and entropy behavior.
• Thermodynamics' four laws:
  • Zeroth law: Systems in thermal equilibrium with a third system are in thermal equilibrium with each other.
  • First law: Energy is conserved; a system's internal energy change equals heat added, minus work done.
  • Second law: Total entropy of an isolated system can only increase or remain constant in ideal scenarios.
  • Third law: As system temperature nears absolute zero, entropy approaches a minimum or zero value.
• Key concepts:
  • System: A space region or matter quantity under study.
  • Surroundings: Everything external to the system.
  • Internal energy: Total energy of molecules within a system.
  • Heat: Energy transfer due to temperature differences.
  • Work: Energy transfer when a force causes displacement.
  • Temperature: Measures average kinetic energy of molecules in a system.
  • Entropy: Measures disorder or randomness in a system.
  • Enthalpy: A thermodynamic property equaling the sum of internal energy and the product of pressure and volume.