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The Physics Portal

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.

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Mars (pronounced /ˈmɑːrz/) is the fourth planet from the Sun in the Solar System. The planet is named after Mars, the Roman god of war. It is also referred to as the "Red Planet" because of its reddish appearance. Mars has two tiny natural moons, Phobos and Deimos, discovered in 1877 by Asaph Hall, which orbit very close to the planet and are thought to be captured asteroids.

Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the volcanoes, valleys, deserts and polar ice caps of Earth. It is the site of Olympus Mons, the highest known mountain in the Solar System, and of Valles Marineris, the largest canyon. Mars has ben the focus of dozens of missions, the most recent being the Mars Scout Program's Phoenix probe...

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Image credit: Soviet space program

Venera 13 and Venera 14 probes were identical probes launched by the Soviet Union in 1981 to study Venus.

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Did you know...

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

...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 August, 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 weight than every person on Earth?
...that every year, the Moon moves 3.82 cm away from Earth?
...that gold leaf is about 500 atoms thick?