The Physics Portal

Physics (Greek: physis – φύσις meaning "nature") is a natural science that involves the study of matter, and its motion through spacetime, as well as all applicable concepts, such as energy and force. This has led to the discovery and understanding of the laws of principles which govern the physical universe. More broadly, Physics is the general analysis of nature, conducted in order to understand how the world and universe behave. One tool which helps with this general analysis is the study of the elementary constituents of the universe and their interactions.

Physics is one of the oldest academic disciplines, perhaps the oldest through its inclusion of astronomy. Evidence exists that the earliest civilizations dating back to beyond 3000 BCE, such as the Sumerians, Ancient Egyptians, and the Indus Valley Civilization, all had a predictive knowledge and a very basic understanding of the motions of the Sun, Moon, and stars. Although originally part of other physical sciences and mathematics, Physics emerged to become a unique modern science during the Scientific Revolution of the 16th century.

Physics is both significant and influential, in part because advances in its understanding have often translated into new technologies, but also because new ideas in physics often resonate with other sciences, mathematics, and philosophy. For example, advances in the understanding of electromagnetism or nuclear physics led directly to the development of new products which have dramatically transformed modern-day society (e.g., television, computers, domestic appliances, and nuclear weapons); advances in thermodynamics led to the development of motorized transport; and advances in mechanics inspired the development of calculus.

Physics also has philosophical implications. It can be historically traced back to ancient Greek philosophy. From Thales' first attempt to characterize matter, to Democritus' deduction that matter ought to reduce to an invariant state, the Ptolemaic astronomy of a crystalline firmament, and Aristotle's book Physics, different Greek philosophers advanced their own theories of nature. Well into the 18th century, physics was known as "Natural philosophy". By the 19th century physics was realized as a positive science and a distinct discipline separate from philosophy and the other sciences. Physics, as with the rest of science, relies on philosophy of science to give an adequate description of the scientific method.

Selected article

The theme for this month is unsolved problems in physics. Some of these problems are theoretical, meaning that existing theories seem incapable of explaining a certain observed phenomenon or experimental result. Other unsolved problems are the result of an inability to in create an experiment to test a proposed theory, or investigate a phenomenon in greater detail.

Hence, theoretical problems are part of quantum gravity, cosmology, general relativity, high energy physics (particle physics), nuclear physics, and others. Empirical phenomena lacking clear scientific explanation are part of cosmology and astronomy, high energy physics(particle physics), astronomy, astrophysics, condensed matter physics, and biological problems approached with physics. Click on the following link to read about this subject, which is supplied with references, and other types of information for further reading.

Main article: List of unsolved problems in physics

Selected picture

This is an artist's concept of the Universe's expansion known as inflation. In this image space is represented at each time by the circular sections. This includes hypothetical, and non-observable portions of the Universe. Note on the left the dramatic expansion (not to scale) occurring in the inflationary epoch. At the center is the accelerated expansion. The scheme is decorated with WMAP images on the left, and with the representation of stars at the appropriate level of development.

Image from WMAP press release, 2006.

Did you know...

Mock mirage of the setting sun

• ...the mirage of astronomical objects is an optical phenomenon, which produces distorted or multiple images of astronomical objects such as the Sun, the Moon, the planets, bright stars and very bright comets

• ...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 nuclear fusion reactions are probably occurring at or above the sun's photosphere; it is a process called solar surface fusion.

• ...that in the Large Hadron Collider the protons, will move at 99.9999991% of the speed of light when accelerated to the energy of 7 TeV?

• ...that, at a speed of 299,792,458 m/s, light can travel from the Earth to the Moon in 1.2 seconds?

• ...that the submarine telescope ANTARES, intended to detect neutrinos, may also be used to observe bioluminescent plankton and fish?

Artist's depiction of the WMAP satellite measuring the Cosmic Microwave Background Radiation to help scientists understand the Big Bang

• ...that lasers can be used to separate two isotopes very efficiently?

• ...that neutron stars are so dense that one neutron star's mass is equal to the mass of 50 earths even if it was just 13 miles across?

• ...that every year, the Moon moves 3.82 cm away from Earth?

• ...that gold leaf is about 500 atoms thick?

• ...that the Big Bang was secured as the best theory of origin of the universe by the discovery of the cosmic microwave background radiation in 1964?

• ...that if we even travel at the speed of light it would take us 15 billion years to cross the universe (or longer ← as the universe is expanding)?

• ...that Neptune was discovered by its gravitational pull on Uranus?

Suggest a fact

Physics news

• June 23, 2010 - Magnetic levitation becomes an inexpensive sensor for analyzing food, water, and other beverages. EurekaAlert

• June 23, 2010 - Simulations reveal hydrogen's transition from one state of matter to another at nearly 3100 degrees Fahrenheit and pressure that is more than 1 million earth atmospheres (think Jupiter). EurekaAlert

• June 23, 2010 - Detecting the movements of single molecules without modifying them. EurekaAlert

• June 13, 2010 -A JAXA probe, the Hayabusa, (artist's impression pictured) returns to Earth, completing a seven-year mission to sample the asteroid 25143 Itokawa.

Artist's depiction of the asteroid sampling probe, Hayabusa.

• June 1, 2010 - New pin sized biomedical sensor pioneered at NASA's GRC, originally for use in space, could measure blood pressure and heart rate resulting in direct societal impact by assisting a lot of people. NASA news

• May 31, 2010 - Using sound to create light, with small losses and very high precision. (PTB)

• May 21, 2010 - Update from JAXA - Venus probe. Solar array paddles deployed and sun acquisition confirmed, at 250,000 km above the Earth. JAXA Venus probe site

• May 20, 2010 - Large amounts of wind and solar can be incorporated onto the power grid without extensive additional infrastructure. - National Renewable Energy Laboratory

• May 14, 2010 - Space Shuttle Atlantis launches on its final scheduled mission, delivering the Rassvet module to the International Space Station.

More physics news is available from Wikinews and the Current Events portal

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).
• - Septermber 1911 - The Sackur-Tetrode Equation is published in Annalen der Physik.
• 29 September 1904 - Nature publishes Wood's letter discredting 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)

Deaths

• 7 September 1783 - Leonhard Euler
• 9 September 2003 - Edward Teller

Things you can do

Summary

• Edit a physics article

Whether you are an expert or a novice, be bold, improve an article by editing it. Practice in the sandbox if you must. But hurry back to fix that glaring error that has been bothering you.

• Join WikiProject Physics.
  • Watch the WikiProject Physics for physics-related issues on Wikipedia.
• Improve Physics Portal
  • Add to Did you know, and Upcoming anniversaries.
  • Add new Selected articles and Selected pictures to the queues.
  • Add to Physics news.
• Review articles
  • Assign importance and quality to unassessed articles (See Physics quality control)
  • Review an article for techno babble and report confusing sections in articles talk page. (Give enough detail to help the editors.)
• Advanced Editing
  • Expand a physics stub.
  • Fix a page needing attention: Modern physics, Classical physics, Other physics topics.
  • Create a requested article.
• Add a requested image.
• Check out other physics-related WikiProjects: WikiProject Science, WikiProject Fluid dynamics, WikiProject Elements.

Check list for physics novices and experts new to wikipedia

• Edit a physics article

Whether you are an expert or a novice, be bold, improve an article by editing it. Practice in the sandbox if you must. But hurry back to fix that glaring error that has been bothering you.

• Register with wikipedia for a user name. (See the username policy)
• Visit the help page
• Add articles to your watch list.
• Check your watchlist on regular basis
• Revert an obvious vandalism edit
• Edit your user page to tell wikipedia enough about you to help other editors get to know you
• Review an article and make a useful comment on the talk page
• Add your name to the WikiProject Physics members list

Activities for physics novices and experts familiar with wikipedia

• Edit a physics article
• Add your name to the WikiProject Physics members list
• Revert Vandalism
• Add or improve diagrams and figures
• Assign importance and quality to unassessed articles (See Physics quality control)
• Review article for techno babble and suggest areas that need improving on talk page (or add clean up tag.)
• Fix a page needing attention: Modern physics, Classical physics, Other physics topics.

Related portals

Associated Wikimedia