Many predictions of general relativity are different from those of classical physics, mainly predictions of time, space geometry, the motion of objects in free fall, and the propagation of light. Examples of these differences include the gravitational time dilation, the gravitational redshift of light, and the gravitational delay time. General relativity predictions have been confirmed in all experiments and physics observations. Although general relativity is not the only relativistic theory of gravity, it is the simplest theory that is consistent with the experimental data. However, there are still many unanswered questions. Fundamentally, there is the question of how this general relativity can be combined with the laws of quantum physics to create a complete and self-consistent quantum theory of gravity.


Einstein's theory has important astrophysical implications. This theory predicts the existence of a black hole region where space and time are distorted in such a way that no one, not even light, can escape from it. There is evidence that black holes of stars and other larger types of black holes are responsible for the powerful radiation emitted by certain astronomical objects, such as active galactic nuclei and microbasics. The curvature of light by gravity can cause the phenomenon of gravitational lensing. General relativity also predicts the existence of gravitational waves. The existence of these waves has been measured indirectly, and there are also several attempts made to measure them directly. Moreover, general relativity is the basis of the cosmological model for the ever-expanding universe.

General relativity becomes important when we look at a system with much smaller radius than mass or mass far larger than the radius. The first case applies to objects that have gravitational collapse like a neutron star or a black hole that has a mass proportional to the mass of a star (though there is also a larger black hole) but with a small radius. The second case applies to cosmology, that is, if space is filled with matter of equal density everywhere, then if we grab the space with ever larger and increasingly larger radii, the mass will increase at a rate proportional to R3. [more...]

The most intelligent scientist in the 20th century, Albert Einstein stated that gravity can make time run more slowly than it should. The effects of gravity greatly affect the flow of time. As it approaches a gravitational source that pulls out the enormous attraction, the time automatically goes slower.

The basic logic is: as humans move closer to the earth's core, time moves more slowly than when humans are on land. Similarly, when humans fly by plane, time runs faster.

Based on research conducted using atomic clocks, weaker gravity in space makes the time to 'fly' faster for several nano seconds. If the atomic clock is brought to a place with different altitudes, then the time shown will not be the same.

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