History of Physics

• Modern Physics encompasses concepts beyond Newtonian physics.
• It explores the behavior of atoms, electrons, and large-scale phenomena via quantum mechanics and Einstein's relativity.

Classical Physics and its Predecessors

• Ancient physics relied on supernatural or mythological explanations.
• Thales of Miletus (624-546 BCE) proposed water as everything's fundamental substance and an early attempt to explain nature using logic.
• Aristotle (384-322 BCE) theorized natural versus forced motion using "four elements" (earth, air, fire, water); his ideas were disproven after dominating for centuries.
• Archimedes (287-212 BCE) contributed to mechanics and hydrostatics as well as principles of buoyancy.
• Ptolemy (90-168 BCE) created a geocentric model influencing astronomical thinking for 1500 years.
• The Islamic Golden Age (8th-14th century) valued knowledge and creativity resulted in significant innovations.
• Alhazen (965-1040) considered the "father of optics," advanced the study of optics establishing the scientific method.
• Avicenna (980-1037) discussed inertia, motion, and impetus, influencing medieval European thought.
• Medieval Europe (5th-15th Century) Scholars focused on reconciling Greek philosophy with Christian theology.
• Roger Bacon (1214-1292) and William of Ockham (1287-1347) advocated for empirical observation and reasoning, Bacon promoted experimentation, and Ockham advocated simpler explanations.

Renaissance and Early Modern Physics (16th - 17th Century)

• There was a shift from religious doctrine and Aristotelian philosophy to experimental approaches.
• Nicolaus Copernicus (1473-1543) proposed a heliocentric model, replacing the geocentric model.
• Johannes Kepler (1571-1630) formulated laws planetary motion.
• Galileo Galilei (1564-1642) championed the scientific method, improved the telescope, and supported heliocentric theory, contributing to classical mechanics.
• Isaac Newton (1643-1727) synthesized predecessor's work in Principia Mathematica (1687), forming the foundation for classical physics with laws of motion and universal gravitation, unifying mechanics, optics, and astronomy.

Classical Physics (17th - 19th Century)

• Principles that govern everyday experiences were formalized.

Electromagnetism (19th Century)

• Hans Christian Ørsted (1820) discovered the link between electricity and magnetism.
• Michael Faraday (1830s-1850s) developed ideas about electric fields and induction.
• James Clerk Maxwell (1860s) combined electricity, magnetism, and light into a unified theory using equations.

History of Modern Physics

• Isaac Newton's Principia (1687) established laws of motion and universal gravitation.
• The Industrial Revolution (late 18th - 19th century) refined Newton's laws.
• Electromagnetism (19th Century) focused on understanding electricity and magnetism.
• James Clerk Maxwell (1860s) unified electricity and magnetism, discovering electromagnetic waves.
• Heinrich Hertz (1887) confirmed electromagnetic waves, leading to radio and communication technologies.
• Thermodynamics and Statistical Mechanics (19th Century) focused on energy, heat, and particle movement.
• Rudolf Claudius introduced entropy.
• Ludwig Boltzmann explained heat and temperature relate to particle motion.
• James Clerk Maxwell focused on statistical mechanics.
• Quantum Mechanics (Early 20th Century) explains the unpredictable behavior of tiny particles.
• Max Planck (1900) introduced 'quanta' of energy to explain black-body radiation using E = hv.
• Albert Einstein (1905) explained photons and the like using the photoelectric effect.
• Niels Bohr (1913) introduced quantized energy levels and orbits and atoms.
• Werner Heisenberg (1925) and Erwin Schrödinger (1926) developed quantum mechanics, including the Uncertainty Principle and wave equations.

Relativity (Early 20th Century)

• Albert Einstein (1905 & 1915) developed special and general relativity relating to space, time, and gravity. In 1905 he developed Special Relativity, which states that time and space aren't fixed.
• 1919 solar eclipse confirmed General Relativity and proved that gravity involves bending space and time was proven using starlight bending.

Particle Physics and Quantum Field Theory (Mid-20th Century)

• Quantum electrodynamics (QED) was developed, describing subatomic particles and interactions.
• Discovery of the Higgs boson in 2012 confirmed the Standard Model, which is the fundamental particle associated that gives mass to other particles.

Cosmology (20th Century)

• Edwin Hubble's (1929) galaxy observations led to the Big Bang theory. Discovery of cosmic microwave background radiation (1965) supported the Big Bang theory.
• String theory, quantum gravity, and unification efforts attempt to solve mysteries on the quantum scale relating to dark energy and matter.

The Twin Paradox: Space and Time in Special Relativity

• The Twin Paradox shows how motion affects time in special relativity, and that length contraction and time dilation occur when relativity affects the passage of time.
• Postulate 1: Laws of physics are the same in all inertial reference frames.
• Postulate 2: The speed of light (c) is constant in a vacuum and doesn't change from any inertial reference frame.
• Time dilation, length contraction, and relativity of simultaneity affect how space and time coordinates change between inertial frames moving at constant velocity.

Lorentz and Galilean Transformations

• Different transformation equations apply depending on relativistic or non-relativistic consideration is a main difference between the Lorentz transformation and the Galilean transformation.
• Spacetime diagrams represent events in space and time, visualizing observer motion.

Time Dilation Factors

• Relative Speed Factors - The faster the relative velocity, the greater the time dilation.
• Not Easily Noticeable - At everyday speeds, the effect is extremely small and practically unnoticeable.

Length Contraction

• The only part of the the object is shortened is relative to the observer.

Lorentz Transformation

• Named after Dutch physicist Hendrik Lorentz
• Explains how space and time change for objects moving close to the speed of light
• Helps everyone agree how fast they are going
• Galilean transformation assumes absolute time and space

Time Dilation

Mathematical Expression:

t 02 √1-

Locating Coordinates

• Use equations to locate coordinates relative to Earth

The Pole and Barn Paradox

• A runner carrying a pole moving at a relativistic speed (close to the speed of light).
• The barn appears shorter for the runner carrying the pole
• Two doors simultaneously close

Superluminal Speeds

• Superluminal speeds refer to the objects motions faster than light
• Key concepts behind superluminal speeds
  • Relativistic motion: Objects moving close to the speed of light.
  • Small viewing angle: The object's motion is nearly aligned with the observer's line of sight.
  • Travel time difference: Light from different positions reaches the observer almost simultaneously.