Journey Through Physics

Overview of Physics: From Ancient Astronomy to Modern Theories

Physics is the study of matter, energy, and force, with the goal of understanding how the universe behaves.
The origins of Western astronomy can be traced back to Mesopotamia, and ancient civilizations like the Sumerians, Egyptians, and Greeks had basic knowledge of the motions of celestial bodies.
Pre-Socratic philosophers rejected non-naturalistic explanations for natural phenomena, and proposed ideas verified by reason and observation, many of which proved successful in experiment.
During the Islamic Golden Age, scholars inherited Aristotelian physics from the Greeks and developed it further, placing emphasis on observation and a priori reasoning, and developing early forms of the scientific method.
The most notable work was The Book of Optics by Ibn al-Haytham, which conclusively disproved the ancient Greek idea about vision and showed the need for a new theory, later provided by Kepler in 1604.
Classical physics became a separate science when early modern Europeans used experimental and quantitative methods to discover what are now considered to be the laws of physics.
Major developments in this period include the replacement of the geocentric model of the Solar System with the heliocentric Copernican model, the laws governing the motion of planetary bodies, and Isaac Newton's discovery and unification of the laws of motion and universal gravitation.
Modern physics began in the early 20th century with the work of Max Planck in quantum theory and Albert Einstein's theory of relativity, which corrected inaccuracies in classical mechanics in certain situations.
The laws comprising classical physics remain widely used for objects on everyday scales travelling at non-relativistic speeds, while quantum mechanics and the theory of relativity simplify to their classical equivalents at such scales.
The Standard Model of particle physics was derived from early work in quantum mechanics and related fields, and theories such as supersymmetry are an active area of research.
Physics relies on philosophy of science and its "scientific method" to advance our knowledge of the physical world, and the development of physics has raised new questions about the nature of space and time, determinism, and metaphysical outlooks.
Core theories of physics include classical mechanics, quantum mechanics, thermodynamics and statistical mechanics, electromagnetism, and special relativity, and any physicist is expected to be literate in them.Overview of Physics: Branches, Applications, and Research
Physics encompasses classical mechanics, acoustics, optics, thermodynamics, and electromagnetism.
Classical mechanics deals with bodies acted on by forces and bodies in motion.
Acoustics studies the production, transmission, and reception of sound.
Optics is concerned with the behavior of light, including visible light, infrared, and ultraviolet radiation.
Thermodynamics deals with the relationships between heat and other forms of energy.
Electricity and magnetism are studied as a single branch of physics since the early 19th century.
Modern physics studies matter and energy under extreme conditions or on a very large or very small scale.
The two chief theories of modern physics are quantum theory and the theory of relativity.
Mathematics provides a compact and exact language used to describe the order in nature.
Applied physics is physics research intended for a particular use, often in engineering and technology.
Physicists use the scientific method to test the validity of a physical theory.
Contemporary research in physics can be broadly divided into nuclear and particle physics, condensed matter physics, atomic, molecular, and optical physics, astrophysics, and applied physics.Overview of Physics: Condensed Matter, Astrophysics, and Current Research
Condensed matter physics deals with the physical properties of matter in condensed phases, including solids and liquids, as well as more exotic phases like superfluids and Bose-Einstein condensates.
Condensed matter physics is the largest field of contemporary physics, with a large overlap with chemistry, materials science, nanotechnology, and engineering.
Astrophysics applies physics theories and methods to study stellar structure, evolution, and cosmology, including the discovery of radio signals emitted by celestial bodies and the expansion of the universe.
Physical cosmology studies the formation and evolution of the universe on its largest scales, including the Big Bang theory and the ΛCDM model.
The Fermi Gamma-ray Space Telescope and other experiments aim to discover new information about dark matter, weakly interacting massive particles, and other mysteries of the universe.
In condensed matter physics, high-temperature superconductivity and the development of spintronics and quantum computers are important unsolved problems.
In particle physics, experimental evidence for physics beyond the Standard Model has been found, including neutrinos with non-zero mass and the Higgs boson.
Future research in particle physics aims to prove or disprove supersymmetry, which extends the Standard Model.
The nature of dark matter and dark energy remains an area of active research in physics.
Despite progress in high-energy, quantum, and astronomical physics, many everyday phenomena involving complexity, chaos, or turbulence are still poorly understood.
Complex phenomena have received growing attention since the 1970s due to modern mathematical methods and computers, and interdisciplinary research has been conducted in areas such as turbulence in aerodynamics and pattern formation in biological systems.
Physics education and career opportunities are available in various fields, including academia, government, and industry.