Portal:Physics
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Physics (from Greek φυσική / physikê means science of nature) is the science concerned with the discovery and understanding of the fundamental laws which govern matter, energy, space, and time. Physics deals with the elementary constituents of the universe and their interactions, as well as the analysis of systems best understood in terms of these fundamental principles. Because physics treats the core workings of the universe, including the quantum mechanical details which underpin all atomic interactions, it can be thought of as the foundational science, upon which stands "the central science" of chemistry, and the earth sciences, biological sciences, and social sciences. Discoveries in basic physics have important ramifications for all of science.
Classical physics traditionally included the fields of mechanics, optics, electricity, magnetism, acoustics and thermodynamics. Modern physics is a term normally used to cover fields which rely on quantum theory, including quantum mechanics, atomic physics, nuclear physics, particle physics and condensed matter physics. The more recent fields of general and special relativity are also usually placed within this category. Although this distinction can be commonly found in older writings, it is of limited current significance as quantum effects are now understood to be of importance even in fields previously considered purely classical.
Physics research is divided into two main branches: experimental physics and theoretical physics. Experimental physics focuses mainly on empirical research, and on the development and testing of theories against practical experiment. Theoretical physics is more closely related to mathematics, and involves generating and working through the mathematical implications of systems of physical theories, even where experimental evidence of their validity may not be immediately available.
Spacecraft propulsion is any method used to change the velocity of spacecraft and artificial satellites. Most spacecraft today are propelled by expelling a gas from the rear of the vehicle at very high speed through a rocket engine nozzle. Most current spacecraft use chemical rockets (bipropellant or solid-fuel) for launch (some, such SpaceShipOne, used jet engines in their first stage). Most satellites have simple reliable chemical thrusters (often monopropellant rockets) or resistojet rockets for orbital station-keeping and some use momentum wheels for attitude control. Soviet bloc satellites have used electric propulsion for decades, and newer Western geo-orbiting spacecraft are starting to use them for north-south stationkeeping. Interplanetary vehicles mostly use chemical rockets as well, although a few have experimentally used ion thrusters. Spacecraft propulsion systems are often first statically tested on the Earth's surface, within the atmosphere but many systems require a vacuum chamber be accurately tested.
A drawing of the Laser Interferometer Space Antenna (LISA), the gravitational wave detector being considered by NASA and ESA. ESA reported that the earliest launch date is 2018.
- ...that the submarine telescope ANTARES, intended to detect neutrinos, may also be used to observe phosphorescent plankton and fish?
- ...that lasers can be used to separate two isotopes very efficiently?
- ...that in mid July, 2008, CERN will open the world's highest energy particle accelerator, the Large Hadron Collider? (CMS detector pictured)
- ...that neutron stars are so dense that a teaspoonful (5 mL) would have more mass than every person on Earth?
- ...that every year, the Moon moves 3.82 cm away from Earth?
- ...that gold leaf is about 300 atoms thick?
- May 1, 2008 A team of nanoscientists have grown twisted nanowires that look like pine trees by twisting the original wire from which the trees were grown. (Science, [1] [2])
- April 13, 2008 John Wheeler died aged 96. "For me, he was the last Titan, the only physics superhero still standing." (Max Tegmark, New York Times)
- December 11, 2007 NASA's voyager 2 probe's recent measurements prove that the solar system is asymmetrical. Several scientists suggest that this is caused by galactic magnetic fields. (CNN)
- November 24, 2007 Speculation about space based solar power plants continues, and with oil prices rising, they might be economical too.
More physics news is available from Wikinews and the Current Events portal
- 13 June 1831 - James Clerk Maxwell's birthday
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Fundamentals: Fundamental concepts | Constants | Physical quantities | Units of measure | Mass | Length | Time | Space | Energy | Matter | Force | Gravity | Electricity | Magnetism | Waves
Basic physics: Introductory physics | Mechanics | Electromagnetism | Statistical mechanics | Thermodynamics | Quantum mechanics | 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 | Pseudophysics | Physics lists | Physics software | Physics stubs
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