Physics
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- This is a discussion of a present category of science. For the work by Aristotle, see Physics (Aristotle). For a history of the science, see History of physics. For the etymology of the word "physics," see physis (φύσις).
Physics, in everyday terms, is the science of matter [1] and its motion; the science that deals with concepts such as force, energy, mass, and charge for example. More accurately, it is the general analysis of nature, conducted in order to understand how the world around us behaves. [2] [3].
In one form or another, physics is one of the oldest academic disciplines, and possibly the oldest through its modern subfield of astronomy. [4] Sometimes synonymous with philosophy, chemistry and even certain branches of mathematics and biology during the last two millennia, physics emerged as a modern science in the 16th century [5] and is now generally distinct from these other disciplines; although the boundaries between physics and all these other subjects still remain difficult to define.
Generally seen as an important subject, advances in physics often translate to the technological sector, and sometimes resonate with the other sciences, and even mathematics and philosophy. For example, advances in the understanding of electromagnetism lead to the widespread use of electrically driven devices (televisions, computers, home appliances etc.); advances in thermodynamics led to the development of motorized transport; and advances in mechanics led to the development of the calculus, quantum chemistry, and the use of instruments like the electron microscope in microbiology.
Today, physics is a broad and highly developed subject that is, for practical reasons, split into several general subfields. In addition to this, it can also be divided into two conceptually different branches: theoretical and experimental physics; the former dealing with the development of new theories, and the latter dealing with the experimental testing of these new, or existing, theories. Despite many important discoveries during the last four centuries, many significant questions about nature still remain unanswered, and many areas of the subject are still highly active.
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[edit] Introduction
- There is also a list of basic physics topics and a list of basic science topics.
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[edit] Scope and goals
Physics is the discipline whose job is to try to understand nature in a very general sense: the fundamental characteristic of physics is that it aims to gain knowledge, and hopefully understanding, of the general properties of world around us. As an example, we can consider asking the following question on the nature of the Universe itself: how many dimensions do we need? Given that we know the Universe to consist of four dimensions (three space dimensions, and one time dimension), we can also ask why the universe picked those particular numbers: why not have four space dimensions? The fact that a choice was made out of a possibility of many means that questions like these fall under the scope of physics. Other general properties of nature include the existence of mass (as in Newton's laws of motion), charge (as in Maxwell's equations), and spin (in Quantum mechanics), amongst others.
However, whilst physics studies the general properties of nature, it will often also study the properties of certain objects within nature. Thus it is also physics whose job it is to describe what happens to, for example, planets whose motion is affected by nearby stars. Generally, the study of the specific objects in nature are shared between the three sciences: biology is roughly responsible for the living organisms, chemistry for the study of the elements and molecules, and physics is given responsibility over all that remains (See the section Relation to mathematics and the other sciences for further information). The fact that physics is delegated all objects besides those covered by biology and chemistry means that it is responsible for the study of a wide range objects and phenomena, from the smallest sub-atomic particles, to the largest galaxies. Included in this are the very most basic objects from which all other things are composed of, and therefore physics is sometimes said to be the "fundamental science".
Generalities aside, physics aims to describe the various phenomena in nature in terms of simpler phenomena: that is, to find the mechanisms for why nature behaves the way it does. Thus, physics aims to both connect the things we see around us to a root cause, and then to try to connect these root causes together in the hope of finding an ultimate reason for why nature is as it is. 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 (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).
[edit] Physics uses the scientific method
Physics uses the scientific method. That is, that the sole test of the validity of a physical theory be comparison with observation. Experiments and observations are to be collected and matched with the predictions of <a href="/wiki/Theor