Related topics: galaxies · physical review letters · dark matter · moon · nasa

Robotic motion in curved space defies standard laws of physics

When humans, animals, and machines move throughout the world, they always push against something, whether it's the ground, air, or water. Until recently, physicists believed this to be a constant, following the law of conservation ...

Using holograms to illuminate de Sitter space

Our understanding of the universe may not be expanding as much as the universe itself. In some cases, our theories about cosmic inflation may feel as if they are deflating into a black hole.

Hibernating insects regrow muscles on demand

Even as gas prices soar, most people don't destroy their car's engine just to save energy—and that's one luxury certain insects have that those humans don't.

Porosity of the moon's crust reveals bombardment history

Around 4.4 billion years ago, the early solar system resembled a game of space rock dodgeball, as massive asteroids and comets, and, later, smaller rocks and galactic debris pummeled the moon and other infant terrestrial ...

Smart earbud will measure how astronauts sleep

Sleep is important for our health and well-being, and bad sleep can negatively impact our attention span, memory, decision-making skills, creativity and judgment.

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Gravitation

Gravitation is a natural phenomenon by which objects with mass attract one another. In everyday life, gravitation is most commonly thought of as the agency which lends weight to objects with mass. Gravitation compels dispersed matter to coalesce, thus accounting for the existence of the Earth, the Sun, and most of the macroscopic objects in the universe. It is responsible for keeping the Earth and the other planets in their orbits around the Sun; for keeping the Moon in its orbit around the Earth; for the formation of tides; for convection, by which fluid flow occurs under the influence of a temperature gradient and gravity; for heating the interiors of forming stars and planets to very high temperatures; and for various other phenomena observed on Earth. Modern physics describes gravitation using the general theory of relativity, in which gravitation is a consequence of the curvature of spacetime which governs the motion of inertial objects. The simpler Newton's law of universal gravitation provides an accurate approximation for most calculations.

The terms gravitation and gravity are mostly interchangeable in everyday use, but a distinction is made in scientific circles. "Gravitation" is a general term describing the phenomenon by which bodies with mass are attracted to one another, while "gravity" refers specifically to the net force exerted by the Earth on objects in its vicinity as well as by other factors, such as the Earth's rotation.

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