Changes

'''Gravitation''' is a natural [[phenomenon]] by which all objects with [[mass]] attract each other,[http://math.ucr.edu/home/baez/physics/Relativity/GR/grav_speed.html Does Gravity Travel at the Speed of Light?], and is one of the [[fundamental forces]] of physics. In everyday life, gravitation is most commonly thought of as the agency that gives objects [[weight]]. It is responsible for keeping the Earth and the other planets in their [[orbit]]s around the Sun; for keeping the [[Moon]] in its orbit around the Earth, for the formation of [[tides]]; for [[convection]] (by which hot fluids rise);  for heating the interiors of forming stars and planets to very high temperatures; and for various other phenomena that we observe. Gravitation is also the reason for the very existence of the [[Earth]], the [[Sun]], and most macroscopic objects in the [[universe]]; without it, matter would not have coalesced into these large masses and [[life]] as we know it would not exist.  

'''Gravitation''' is a natural [[phenomenon]] by which all objects with [[mass]] attract each other,[http://math.ucr.edu/home/baez/physics/Relativity/GR/grav_speed.html Does Gravity Travel at the Speed of Light?], and is one of the [[fundamental forces]] of physics. In everyday life, gravitation is most commonly thought of as the agency that gives objects [[weight]]. It is responsible for keeping the Earth and the other planets in their [[orbit]]s around the Sun; for keeping the [[Moon]] in its orbit around the Earth, for the formation of [[tides]]; for [[convection]] (by which hot fluids rise);  for heating the interiors of forming stars and planets to very high temperatures; and for various other phenomena that we observe. Gravitation is also the reason for the very existence of the [[Earth]], the [[Sun]], and most macroscopic objects in the [[universe]]; without it, matter would not have coalesced into these large masses and [[life]] as we know it would not exist.  

<center>For lessons on the [[topic]] of '''''Gravity''''', follow [http://nordan.daynal.org/wiki/index.php?title=Category:Gravity this link].</center>

<center>For lessons on the [[topic]] of '''''Gravity''''', follow [http://nordan.daynal.org/wiki/index.php?title=Category:Gravity this link].</center>

Modern [[physics]] describes gravitation using the [[general theory of relativity]], but the much simpler [[Newton's law of universal gravitation]] provides an excellent approximation in most cases. The terms '''gravitation''' and '''gravity''' are mostly interchangeable in everyday use, but in scientific usage a distinction may be made. "Gravitation" is a general term describing the attractive influence that all objects with mass exert on each other, while "gravity" specifically refers to a [[force]] that is supposed in some theories (such as Newton's) to be the cause of this attraction. By contrast, in [[general relativity]] gravitation is due to spacetime curvatures that cause [[inertia]]lly moving objects to accelerate towards each other.  

Modern [[physics]] describes gravitation using the [[general theory of relativity]], but the much simpler [[Newton's law of universal gravitation]] provides an excellent approximation in most cases. The terms '''gravitation''' and '''gravity''' are mostly interchangeable in everyday use, but in scientific usage a distinction may be made. "Gravitation" is a general term describing the attractive influence that all objects with mass exert on each other, while "gravity" specifically refers to a [[force]] that is supposed in some theories (such as Newton's) to be the cause of this attraction. By contrast, in [[general relativity]] gravitation is due to spacetime curvatures that cause [[inertia]]lly moving objects to accelerate towards each other.