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  2. Space - Wikipedia

    en.wikipedia.org/wiki/Space

    Space. Space is a three-dimensional continuum containing positions and directions. [1] In classical physics, physical space is often conceived in three linear dimensions. Modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum known as spacetime. [2]

  3. Space physics - Wikipedia

    en.wikipedia.org/wiki/Space_physics

    Space physics, also known as space plasma physics, is the study of naturally occurring plasmas within Earth's upper atmosphere and the rest of the Solar System. It includes the topics of aeronomy , aurorae , planetary ionospheres and magnetospheres , radiation belts , and space weather (collectively known as solar-terrestrial physics [1] ).

  4. Spacetime - Wikipedia

    en.wikipedia.org/wiki/Spacetime

    t. e. In physics, spacetime is a mathematical model that fuses the three dimensions of space and the one dimension of time into a single four-dimensional continuum. Spacetime diagrams are useful in visualizing and understanding relativistic effects such as how different observers perceive where and when events occur.

  5. Physics - Wikipedia

    en.wikipedia.org/wiki/Physics

    Pure physics is a branch of fundamental science (also called basic science). Physics is also called " the fundamental science" because all branches of natural science like chemistry, astronomy, geology, and biology are constrained by laws of physics. [60] Similarly, chemistry is often called the central science because of its role in linking ...

  6. Position and momentum spaces - Wikipedia

    en.wikipedia.org/wiki/Position_and_momentum_spaces

    Position and momentum spaces. In physics and geometry, there are two closely related vector spaces, usually three-dimensional but in general of any finite dimension. Position space (also real space or coordinate space) is the set of all position vectors r in Euclidean space, and has dimensions of length; a position vector defines a point in space.

  7. Absolute space and time - Wikipedia

    en.wikipedia.org/wiki/Absolute_space_and_time

    The three-dimensional linear vector space R3 is a set of all radius vectors. The space R3 is endowed with a scalar product , . Time is a scalar which is the same in all space E3 and is denoted as t. The ordered set { t } is called a time axis. Motion (also path or trajectory) is a function r : Δ → R3 that maps a point in the interval Δ from ...

  8. Parsec - Wikipedia

    en.wikipedia.org/wiki/Parsec

    The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to 3.26 light-years or 206,265 astronomical units (AU), i.e. 30.9 trillion kilometres (19.2 trillion miles ). [a] The parsec unit is obtained by the use of parallax and trigonometry, and is ...

  9. Expansion of the universe - Wikipedia

    en.wikipedia.org/wiki/Expansion_of_the_universe

    The expansion of the universe is the increase in distance between gravitationally unbound parts of the observable universe with time. [1] It is an intrinsic expansion, so it does not mean that the universe expands "into" anything or that space exists "outside" it. To any observer in the universe, it appears that all but the nearest galaxies ...