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Physics, Physics

P. Feynman, R. B. Leighton, M. Sands (1963), The Feynman Lectures on Physics , ISBN 0-201-02116-1 Hard-cover. p.1-1 Feynman begins with the atomic hypothesis, as his most compact statement of all scientific knowledge: "If, in some cataclysm, all of scientific knowledge were to be destroyed, and only one sentence passed on to the next generations ..., what statement would contain the most information in the fewest words? I believe it is ... that all things are made up of atoms little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another. ... " vol.

H.D. Young & R.A. Freedman, University Physics with Modern Physics : 11th Edition: International Edition (2004), Addison Wesley. Chapter 1, section 1.1, page 2 has this to say: "Physics is an experimental science. Physicists observe the phenomena of nature and try to find patterns and principles that relate these phenomena. These patterns are called physical theories or, when they are very well established and of broad use, physical laws or principles." Steve Holzner, Physics for Dummies (2006), Wiley. Chapter 1, page 7 says: "Physics is the study of your world and the world and universe around you." See Amazon Online Reader: Physics For Dummies (For Dummies(Math & Science)) , retrieved 24 Nov 2006 Note: The term 'universe' is defined as everything that physically exists: the entirety of space and time, all forms of matter, energy and momentum, and the physical laws and constants that govern them. However, the term 'universe' may also be used in slightly different contextual senses, denoting concepts such as the cosmos or the philosophical world.

For example, the ancient Chinese observed that certain rocks (lodestone) were attracted to one another by some invisible force. This effect was later called magnetism, and was first rigorously studied in the 17th century. A little earlier than the Chinese, the ancient Greeks knew of other objects such as amber, that when rubbed with fur would cause a similar invisible attraction between the two. This was also first studied rigorously in the 17th century, and came to be called electricity. Thus, physics had come to understand two observations of nature in terms of some root cause (electricity and magnetism). However, further work in the 19th century revealed that these two forces were just two different aspects of one force electromagnetism. This process of "unifying" forces continues today (see section Current research for more information).

Of course, all theories, including those called scientific laws, can always be replaced by more accurate, generalized statements if a disagreement of theory with observed data is ever found. Some principles, such as Newton's laws of motion, are still generally called "laws" even though they are now known to be limiting cases of newer theories. Thus, for example, in Thomas Brody (1993, Luis de la Pea and Peter Hodgson, eds.) The Philosophy Behind Physics ISBN 0-387-55914-0, pp 1824 (Chapter 2), explains the 'epistemic cycle' in which a student of physics discovers that physics is not a finished product but is instead the process of creating product.

Since the twentieth century, most individual physicists have specialized in either theoretical physics or experimental physics. In contrast, almost all the successful theorists in biology and chemistry (e.g. American quantum chemist and biochemist Linus Pauling) have also been experimentalists, although this is changing as of late.

Theoretical physics has historically rested on philosophy and metaphysics; electromagnetism was unified this way. See, for example, the influence of Kant and Ritter on Oersted.

For example, the atom of nineteenth century physics was denigrated by some, including Ernst Mach's critique of Ludwig Boltzmann's formulation of statistical mechanics. By the end of World War II, the atom was no longer deemed hypothetical.

The distinction, however, is not always clear-cut. There is a large area of research intermediate between physics and mathematics, known as mathematical physics.

The principles of physics find applications throughout the other natural sciences as some phenomena studied in physics, such as the conservation of energy, are common to all material systems. Other phenomena, such as superconductivity, stem from these laws, but are not laws themselves because they only appear in some systems. Physics is often said to be the "fundamental science" (chemistry is sometimes included), because each of the other disciplines (biology, chemistry, geology, material science, engineering, medicine etc.) deals with particular types of material systems that obey the laws of physics.

The structure, reactivity, and properties of a chemical compound are determined by the properties of the underlying molecules, which can be described by areas of physics such as quantum mechanics (called in this case quantum chemistry), thermodynamics, and electromagnetism.

Physics, as with the rest of science, relies on philosophy of science to give an adequate description of the scientific method.

Several theories were proposed, the majority of which were disproved. Early physical theories were largely couched in philosophical terms, and never verified by systematic experimental testing as is popular today. Many of the commonly accepted works of Ptolemy and Aristotle are not always found to match everyday observations. Even so, Chinese and Indian philosophers and astronomers gave many correct descriptions in atomism and astronomy, and the Greek thinker Archimedes derived many correct quantitative descriptions of mechanics and hydrostatics. A more experimental physics began taking shape among medieval Muslim physicists, while modern physics largely took shape among early modern European physicists.

Historically, condensed matter physics grew out of solid-state physics, which is now considered one of its main subfields. The term condensed matter physics was apparently coined by Philip Anderson when he renamed his research group previously solid-state theory in 1967. In 1978, the Division of Solid State Physics at the American Physical Society was renamed as the Division of Condensed Matter Physics.

It may also be called "high energy physics", because many elementary particles do not occur naturally, but are created only during high energy collisions of other particles, as can be detected in particle accelerators.

Because astrophysics is a broad subject, astrophysicists typically apply many disciplines of physics, including mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and molecular physics.

An applied physics curriculum usually contains a few classes in an applied discipline, like geology or electrical engineering. It usually differs from engineering in that an applied physicist may not be designing something in particular, but rather is using physics or conducting physics research with the aim of developing new technologies or solving a problem. The approach is similar to that of applied mathematics. Applied physicists can also be interested in the use of physics for scientific research. For instance, people working on accelerator physics might seek to build better particle detectors for research in theoretical physics.

For example, Statics, a subfield of mechanics, is used in the building of bridges and other structures. The understanding and use of acoustics results in better concert halls; similarly, the use of optics creates better optical devices. An understanding of physics makes for more realistic flight simulators, video games, and movies, and is often critical in forensic investigations.

Source: Wikipedia > Physics