Introduction to Physics

• Physics is the natural science of matter and its motion through space-time, including energy and force
• In broader terms, physics is the general analysis of nature to understand the behavior of the universe
• Physics is among the oldest academic fields, potentially the oldest because it includes astronomy
• Progress in physics often leads to technological advances
• Understanding electromagnetism, solid-state physics, and nuclear physics has directly enabled new technologies
• These technologies include televisions, computers, appliances, and nuclear weapons
• Thermodynamics advancements spurred industrialization, while mechanics inspired calculus development
• Physics is integral to engineering
• Physics encompasses diverse topics, including mechanics, electricity, magnetism, thermodynamics, optics, acoustics, and nuclear physics
• Differentiating these fields involves considering scale (micro- or macro-) and the systems studied
• Classical physics focuses on macroscopic systems like everyday objects at speeds far below light speed
• Modern physics explores microscopic systems involving atoms, subatomic particles, and electromagnetic radiation and examines relativistic phenomena
• Physics is both theoretical and experimental
• Physicists employ the scientific method to create and test hypotheses, leading to the discovery of physical laws

Mechanics

• Mechanics studies the motion of bodies under the influence of forces
• Mechanics includes:
  • Statics: the study of bodies at rest
  • Kinematics: the study of motion without considering its causes
  • Dynamics: the study of motion and its causes
• Mechanics problems involve predicting body responses to different forces
• Accurate predictions require understanding the environment of these bodies, including other bodies, gravity, and pressure
• Mechanics is divided into classical mechanics, for macroscopic objects at low speeds, and quantum mechanics, for microscopic objects
• Relativistic mechanics deals with objects moving close to the speed of light
• Classical mechanics, or Newtonian mechanics, consists of physical laws describing body motion under forces
• Classical mechanics is effective at describing the macroscopic world
• Isaac Newton formulated the laws of classical mechanics in his Principia Mathematica (1687)
• Newton's Laws include:
  • The Law of Inertia
  • Newton’s Second Law of Motion
  • The Law of Reciprocal Actions
• Newton's laws of motion and his law of universal gravitation present a complete view of mechanics

Electromagnetism

• Deals with interactions between electric currents/fields and magnetic fields
• An electric field exerts force on other charges, attracting or repelling them
• Magnetic fields arise from moving electric charges, such as current in a wire
• Electromagnetism is described by classical electrodynamics, incorporating classical mechanics with the electromagnetic force
• Electrodynamics effects are negligible at microscopic scales, where quantum mechanics is more effective
• Quantum electrodynamics (QED) is the quantum theory of electrodynamics
• Electromagnetism is applied in electric power, telecommunications, and electronics

Thermodynamics

• Thermodynamics is related to heat, temperature, energy, and work
• Thermodynamics is relevant for engineering, chemistry, and biology
• The four laws of thermodynamics are:
  • The zeroth law: If two systems are in thermal equilibrium with a third, they are in equilibrium with each other
  • The first law: Energy is conserved
  • The second law: The total entropy of an isolated system increases over time
  • The third law: Entropy approaches a constant as temperature nears absolute zero

Optics

• Optics studies light behavior and properties, its interactions with matter, and the instruments that use or detect it
• Optics generally describes visible, ultraviolet, and infrared light
• Light is an electromagnetic wave
• Wave optics phenomena depend on the wave nature of light
• Particle or quantum optics phenomena depend on light behaving as photons
• Physical optics studies the nature of light itself
• Optical instruments include lenses, mirrors, telescopes, microscopes, and cameras
• Optics is used in medicine, engineering, and computer science

Acoustics

• Acoustics studies mechanical waves (vibration, sound, ultrasound, infrasound) in gases, liquids, and solids
• Sub-areas of acoustics include aeroacoustics, audio signal processing, architectural acoustics, bioacoustics, engineering acoustics, noise control, psychoacoustics, speech, ultrasound, underwater acoustics, and vibration
• Applications in audio recording, medical imaging, industrial testing, and musical instrument design
• Acoustic waves are used for detection, diagnosis, and therapy in medicine, including ultrasound
• Acoustics relates to music, sound, speech, and hearing
• Acoustic phenomena play a role in geology, manufacturing, and architecture

Nuclear Physics

• Nuclear physics studies the constituents and interactions of atomic nuclei
• Common applications include nuclear power and nuclear weapons
• Nuclear medicine, MRI, agriculture, and industrial applications
• Nuclear physics research areas are:
  • Nuclear fusion
  • Nuclear fission
  • Radioactive decay
  • Nuclear reactions
• Nuclear physics is also used to study the origin and evolution of the universe