Portal:Physics
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Physics is the natural science of matter, involving the study of matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. Physics is one of the most fundamental scientific disciplines. A scientist who specializes in the field of physics is called a physicist.
Physics is one of the oldest academic disciplines and, through its inclusion of astronomy, perhaps the oldest. Over much of the past two millennia, physics, chemistry, biology, and certain branches of mathematics were a part of natural philosophy, but during the Scientific Revolution in the 17th century, these natural sciences branched into separate research endeavors. Physics intersects with many interdisciplinary areas of research, such as biophysics and quantum chemistry, and the boundaries of physics are not rigidly defined. New ideas in physics often explain the fundamental mechanisms studied by other sciences and suggest new avenues of research in these and other academic disciplines such as mathematics and philosophy.
Advances in physics often enable new technologies. For example, advances in the understanding of electromagnetism, solid-state physics, and nuclear physics led directly to the development of new products that have dramatically transformed modern-day society, such as television, computers, domestic appliances, and nuclear weapons; advances in thermodynamics led to the development of industrialization; and advances in mechanics inspired the development of calculus. (Full article...)
The electron (
e−
, or
β−
in nuclear reactions) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no known components or substructure. The electron's mass is approximately 1/1836 that of the proton. Quantum mechanical properties of the electron include an intrinsic angular momentum (spin) of a half-integer value, expressed in units of the reduced Planck constant, ħ. Being fermions, no two electrons can occupy the same quantum state, per the Pauli exclusion principle. Like all elementary particles, electrons exhibit properties of both particles and waves: They can collide with other particles and can be diffracted like light. The wave properties of electrons are easier to observe with experiments than those of other particles like neutrons and protons because electrons have a lower mass and hence a longer de Broglie wavelength for a given energy.
Did you know -
![Neptune](http://upload.wikimedia.org/wikipedia/commons/thumb/b/b9/Neptune_Voyager2_color_calibrated.png/125px-Neptune_Voyager2_color_calibrated.png)
- ... that Aristotle's ideas of physics held that because an object could not move without an immediate source of energy, arrows created a vacuum behind them that pushed them through the air.
- ... that there are up to 6 candidates for the Theory of everything, minus String theory and Loop quantum gravity?
Selected image -
The Hubble Deep Field (HDF) is an image of a small region in the constellation Ursa Major, constructed from a series of observations by the Hubble Space Telescope. It covers an area 2.5 arcminutes across, two parts in a million of the whole sky
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The Hubble Deep Field
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Details from the Hubble Deep Field illustrate the wide variety of galaxy shapes, sizes and colours found in the distant universe.
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September anniversaries
- 6 September 1809 - Sir George Cayley identifies the four aerodynamic forces
- 3 September 1821 - Faraday discovers electromagnetic rotation (the principle behind the electric motor).
- - September 1911 - The Sackur-Tetrode Equation is published in Annalen der Physik.
- 29 September 1904 - Nature publishes Wood's letter discrediting N-rays.
- 27 September 1905 - E=mc2 --- Annalen der Physik publishes the Mass–Energy equivalence
- 9 September 1934: The American Rocket Society (ARS) launched Rocket No. 4 to 400 feet.
- 17 September 1959 - The first powered X-15 flight.
- 9 September 1959 - The Atlas 10-D rocket is launched.
- 1 September 1974 - Pioneer 11 sends polar images of Jupiter.
- 20 September 1979 - The High Energy Astronomical Observatory (HEAO) 3 is launched.
- - September 1981 - Invention of the scanning tunneling microscope.
Births
- 22 September 1791 Michael Faraday (d.1867)
- 29 September 1901 Enrico Fermi
Deaths
- 5 September 1906 - Ludwig Boltzmann
- 7 September 1783 - Leonhard Euler
- 9 September 2003 - Edward Teller
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Fundamentals: Concepts in physics | Constants | Physical quantities | Units of measure | Mass | Length | Time | Space | Energy | Matter | Force | Gravity | Electricity | Magnetism | Waves
Basic physics: Mechanics | Electromagnetism | Statistical mechanics | Thermodynamics | Quantum mechanics | Theory of relativity | Optics | Acoustics
Specific fields: Acoustics | Astrophysics | Atomic physics | Molecular physics | Optical physics | Computational physics | Condensed matter physics | Nuclear physics | Particle physics | Plasma physics
Tools: Detectors | Interferometry | Measurement | Radiometry | Spectroscopy | Transducers
Background: Physicists | History of physics | Philosophy of physics | Physics education | Physics journals | Physics organizations
Other: Physics in fiction | Physics lists | Physics software | Physics stubs
Physics topics
Classical physics traditionally includes the fields of mechanics, optics, electricity, magnetism, acoustics and thermodynamics. The term Modern physics is normally used for fields which rely heavily on quantum theory, including quantum mechanics, atomic physics, nuclear physics, particle physics and condensed matter physics. General and special relativity are usually considered to be part of modern physics as well.
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