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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]
The boundary between space and Earth, at an altitude of 100 km, roughly where the yellow line of airglow is visible. Outer space (or simply space) is the expanse beyond celestial bodies and their atmospheres. It contains ultra-low levels of particle densities, constituting a near-perfect vacuum [1] of predominantly hydrogen and helium plasma ...
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 ...
Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest include planets, moons, stars, nebulae, galaxies, meteoroids, asteroids, and comets.
Space physics – study of plasmas as they occur naturally in the Earth's upper atmosphere (aeronomy) and within the Solar System. Solar physics – Sun and its interaction with the remainder of the Solar System and interstellar space. Stellar astronomy – concerned with Star formation, physical properties, main sequence life span, variability ...
Space exploration is the use of astronomy and space technology to explore outer space. [1] While the exploration of space is currently carried out mainly by astronomers with telescopes, its physical exploration is conducted both by uncrewed robotic space probes and human spaceflight. Space exploration, like its classical form astronomy, is one ...
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 ...
t. e. In physics, the special theory of relativity, or special relativity for short, is a scientific theory of the relationship between space and time. In Albert Einstein 's 1905 treatment, the theory is presented as being based on just two postulates: [p 1] [1] [2] The laws of physics are invariant (identical) in all inertial frames of ...