History and Branches of Physics

Physics is the study of matter, its motion and behavior through space and time.

Physics is one of the oldest academic disciplines and, through its inclusion of astronomy, perhaps the oldest.

Physics intersects with many other disciplines, such as biophysics and quantum chemistry, and the boundaries of physics are not rigidly defined.

Advances in physics often enable advances in new technologies.

The origins of Western astronomy can be found in Mesopotamia, and all Western efforts in the exact sciences are descended from late Babylonian astronomy.

Egyptian astronomers left monuments showing knowledge of the constellations and the motions of the celestial bodies, while Greek poet Homer wrote of various celestial objects in his Iliad and Odyssey; later Greek astronomers provided names, which are still used today, for most constellations visible from the Northern Hemisphere.

Natural philosophy has its origins in Greece during the Archaic period (650 BCE – 480 BCE), when pre-Socratic philosophers like Thales rejected non-naturalistic explanations for natural phenomena and proclaimed that every event had a natural cause.

By contrast, the Western Roman Empire fell in the fifth century, and this resulted in a decline in intellectual pursuits in the western part of Europe.

Classical physics is the body of knowledge that is based on the work of ancient Greek and Roman philosophers.

This body of knowledge includes the study of the natural world and the laws that govern it.

In the 6th century, Isidore of Miletus compiled an important compilation of Archimedes' works.

In the 6th century, John Philoponus, a Byzantine scholar, questioned Aristotle's teaching of physics and noted its flaws.

Aristotle's physics was not scrutinized until Philoponus appeared; unlike Aristotle, who based his physics on verbal argument, Philoponus relied on observation.

Philoponus' criticism of Aristotelian principles of physics served as an inspiration for Galileo Galilei ten centuries later, during the Scientific Revolution.

Galileo cited Philoponus substantially in his works when arguing that Aristotelian physics was flawed.

Islamic scholarship inherited Aristotelian physics from the Greeks and during the Islamic Golden Age developed it further, especially placing emphasis on observation and a priori reasoning, developing early forms of the scientific method.

The most notable innovations were in the field of optics and vision, which came from the works of many scientists like Ibn Sahl, Al-Kindi, Ibn al-Haytham, Al-Farisi and Avicenna.

The most notable work was The Book of Optics (also known as Kitāb al-Manāẓir), written by Ibn al-Haytham, in which he conclusively disproved the ancient Greek idea about vision and came up with a new theory.

In the book, he presented a study of the phenomenon of the camera obscura (his thousand-year-old version of the pinhole camera) and delved further into the way the eye itself works.

Using dissections and the knowledge of previous scholars, he was able to begin to explain how light enters the eye.

He asserted that the light ray is focused, but the actual explanation of how light projected to the back of the eye had to wait until 1604.

His Treatise on Light explained the camera obscura, hundreds of years before the modern development of photography.

The seven-volume Book of Optics (Kitab al-Manathir) hugely influenced thinking across disciplines from the theory of visual perception to the nature of perspective in medieval art, in both the East and the West, for more than 600 years.

Many later European scholars and fellow polymaths, from Robert Grosseteste and Leonardo da Vinci to René Descartes, Johannes Kepler and Isaac Newton, were in his debt. Indeed, the influence of Ibn al-Haytham's Optics ranks alongside that of Newton's work of the same title, published 700 years later.

The history of physics can be traced back to ancient Greek philosophy.

Classical physics is the physics that was used in the 19th century and is still used today.

In the early 20th century, Max Planck and Albert Einstein developed quantum theory and relativity.

Modern physics began in the early 20th century with the work of Werner Heisenberg, Erwin Schrödinger, and Paul Dirac.

The Standard Model of particle physics is the most widely accepted theory of the fundamental particles in the universe.

Philosophy of physics involves issues such as the nature of space and time, determinism, and metaphysical outlooks such as empiricism, naturalism, and realism.

Classical mechanics is the most fundamental theory of physics and is used to describe the motion of objects on a normal scale.

Chaos theory is a branch of classical mechanics that studies the behavior of systems that are sensitive to initial conditions.

Quantum mechanics is a branch of physics that deals with the behavior of matter and energy on a very small or extremely large scale.

Thermodynamics is a branch of physics that studies the relationships between heat and other forms of energy.

Electricity and magnetism have been studied as a single branch of physics since the early 19th century.

Modern physics is concerned with the behavior of matter and energy under extreme conditions or on a very large or very small scale.