general relativity بازانیگی ِ هروین bâzânigi-ye harvin
*Fr.: relativité générale*
The theory of → *gravitation* developed by Albert Einstein
(1916) that describes the gravitation as the → *space-time*
curvature caused by the presence of matter or energy.
Mass creates a → *gravitational field* which
distorts the space and changes the flow of time. In other words, mass
causes a deviation of the → *metric* of
space-time continuum from that of the "flat" space-time structure described by the
→ *Euclidean geometry* and treated in
→ *special relativity*.
General relativity developed from the
→ *principle of equivalence* between
gravitational and inertial forces.
According to general relativity, photons follow a curved path
in a gravitational field. This prediction was confirmed by the
measurements of star positions near the solar limb during the
total eclipse of 1919. The same effect is seen in the
delay of radio signals coming from distant space probes when
grazing the Sun's surface. Moreover, the space curvature caused by
the Sun makes the → *perihelion*
of Mercury's orbit advance by 43'' per century more than that predicted by
Newton's theory of gravitation. The → *perihelion advance*
can reach several degrees per year for
→ *binary pulsar* orbits.
Another effect predicted by general
relativity is the → *gravitational reddening*.
This effect is verified in the → *redshift*
of spectral lines in the
solar spectrum and, even more obviously, in
→ *white dwarf*s. Other predictions of the theory include
→ *gravitational lensing*,
→ *gravitational wave*s, and the
invariance of Newton's → *gravitational constant*. → * general*; → * relativity*. |