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  2. Hubble Space Telescope - Wikipedia

    en.wikipedia.org/wiki/Hubble_Space_Telescope

    The Hubble Space Telescope (HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versatile, renowned as a vital research tool and as a public relations boon for astronomy.

  3. Physics - Wikipedia

    en.wikipedia.org/wiki/Physics

    The word physics comes from the Latin physica ('study of nature'), which itself is a borrowing of the Greek φυσική (phusikḗ 'natural science'), a term derived from φύσις (phúsis 'origin, nature, property'). [6] [7] [8]

  4. P versus NP problem - Wikipedia

    en.wikipedia.org/wiki/P_versus_NP_problem

    Just as the class P is defined in terms of polynomial running time, the class EXPTIME is the set of all decision problems that have exponential running time. In other words, any problem in EXPTIME is solvable by a deterministic Turing machine in O (2 p ( n ) ) time, where p ( n ) is a polynomial function of n .

  5. Big Bang - Wikipedia

    en.wikipedia.org/wiki/Big_Bang

    The Big Bang is a physical theory that describes how the universe expanded from an initial state of high density and temperature. [1] The concept of an expanding universe was scientifically originated by physicist Alexander Friedmann in 1922 with the mathematical derivation of the Friedmann equations.

  6. Friction - Wikipedia

    en.wikipedia.org/wiki/Friction

    However, despite the complexity of the fundamental physics behind friction, the relationships are accurate enough to be useful in many applications. "Negative" coefficient of friction As of 2012 [update] , a single study has demonstrated the potential for an effectively negative coefficient of friction in the low-load regime , meaning that a ...

  7. Xenon - Wikipedia

    en.wikipedia.org/wiki/Xenon

    Given a total mass of the atmosphere of 5.15 × 10 18 kilograms (1.135 × 10 19 lb), the atmosphere contains on the order of 2.03 gigatonnes (2.00 × 10 9 long tons; 2.24 × 10 9 short tons) of xenon in total when taking the average molar mass of the atmosphere as 28.96 g/mol which is equivalent to some 394-mass ppb.

  8. Mechanical equilibrium - Wikipedia

    en.wikipedia.org/wiki/Mechanical_equilibrium

    In addition to defining mechanical equilibrium in terms of force, there are many alternative definitions for mechanical equilibrium which are all mathematically equivalent. In terms of momentum, a system is in equilibrium if the momentum of its parts is all constant. In terms of velocity, the system is in equilibrium if velocity is constant.

  9. Cosmology - Wikipedia

    en.wikipedia.org/wiki/Cosmology

    The term cosmology was first used in English in 1656 in Thomas Blount's Glossographia, [2] and in 1731 taken up in Latin by German philosopher Christian Wolff in Cosmologia Generalis. [3] Religious or mythological cosmology is a body of beliefs based on mythological , religious , and esoteric literature and traditions of creation myths and ...