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 emerged as unique research endeavors in their own right. 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 magnetosphere of Jupiter is the cavity created in the solar wind by Jupiter's magnetic field. Extending up to seven million kilometers in the Sun's direction and almost to the orbit of Saturn in the opposite direction, Jupiter's magnetosphere is the largest and most powerful of any planetary magnetosphere in the Solar System, and by volume the largest known continuous structure in the Solar System after the heliosphere. Wider and flatter than the Earth's magnetosphere, Jupiter's is stronger by an order of magnitude, while its magnetic moment is roughly 18,000 times larger. The existence of Jupiter's magnetic field was first inferred from observations of radio emissions at the end of the 1950s and was directly observed by the Pioneer 10 spacecraft in 1973.
Jupiter's internal magnetic field is generated by electrical currents in the planet's outer core, which is theorized to be composed of liquid metallic hydrogen. Volcanic eruptions on Jupiter's moon Io eject large amounts of sulfur dioxide gas into space, forming a large torus around the planet. Jupiter's magnetic field forces the torus to rotate with the same angular velocity and direction as the planet. The torus in turn loads the magnetic field with plasma, in the process stretching it into a pancake-like structure called a magnetodisk. In effect, Jupiter's magnetosphere is internally driven, shaped primarily by Io's plasma and its own rotation, rather than by the solar wind as at Earth's magnetosphere. Strong currents in the magnetosphere generate permanent aurorae around the planet's poles and intense variable radio emissions, which means that Jupiter can be thought of as a very weak radio pulsar. Jupiter's aurorae have been observed in almost all parts of the electromagnetic spectrum, including infrared, visible, ultraviolet and soft X-rays. (Full article...)Did you know -
- ... that lasers can be used to separate two isotopes very efficiently?
- ... that your feet are slightly younger than your head, because time runs slow at a lower Gravitational Potential. This is a consequence of Gravitational Time Dilation
- ...that Max Planck created a system of measurement based solely on natural units?
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July anniversaries
- July 1654 – Blaise Pascal's letters to Pierre de Fermat on the "Problem of Points"
- July 1820 – Hans Christian Ørsted published pamphlet about the relation between electricity and magnetism
- July 1849 – Fizeau publishes results of speed of light experiment.
- July 1914 – AT&T tested the first working transcontinental telephone line when the president of the company spoke from one coast to the other. Months later Alexander Graham Bell repeated his famous statement over the phone in New York City which was heard by Dr. Watson in San Francisco.
- July 1957 – John Bardeen, Leon Cooper and Robert Schrieffer submit detailed research report, "Theory of Superconductivity" to the Physical Review (it was published in December).
- July 1994 – Comet Shoemaker–Levy 9 collides with Jupiter.
- 16 July 1945 – Trinity test, named by J. Robert Oppenheimer.
- 16 July 1969 – Apollo 11 launched.
- 20 July 1969 – Apollo 11 landed on the Moon.
- 23 July 1995 – Comet Hale-Bopp discovered.
- 2 July 1876 - Harriet Brooks was born; noted for research in nuclear transmutations and for discovering the Atomic recoil.
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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
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Background: Physicists | History of physics | Philosophy of physics | Physics education | Physics journals | Physics organizations
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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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