1846 - Urbain
Le Verrier and John
Couch Adams, studying Uranus
orbit, independently prove that another, farther planet must exist. The planet
will be found at the predicted moment and position, and will be called Neptune.
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1855 - Leverrier observes
a 35 arcsecond per century excess precession
of Mercury's
orbit and attributes it
to another planet, inside Mercury's orbit. The planet will never be found.
1876 - William Clifford
suggests that the motion of matter may be due to changes in the geometry of
space
1882 - Simon Newcomb observes
a 43 arcsecond per century excess precession of Mercury's orbit
1921 - T. Kaluza demonstrates
that a five-dimensional version of Einstein's equations unifies gravitation
and electromagnetism
1937 - Fritz Zwicky states
that galaxies could act
as gravitational lenses
1937 - Albert Einstein,
Leopold Infeld, and Banesh Hoffman show that the geodesic equations of general
relativity can be deduced from its field equations
1968 - Irwin Shapiro presents
the first detection of the Shapiro delay
1968 - Kenneth Nordtvedt
studies a possible violation of the weak equivalence principle for self-gravitating
bodies and proposes a new test of the weak equivalence principle based on
observing the relative motion of the Earth
and Moon in the Sun's gravitational field
1976 - Robert Vessot and
Martin Levine use a hydrogenmaser clock on a Scout D
rocket to test the gravitational
redshift predicted by the equivalence principle to approximately 0.007%
1979 - Dennis Walsh, Robert
Carswell, and Ray Weymann discover the gravitationally lensed quasar
Q0957+561
1982 - Joseph Taylor and
Joel Weisberg show that the rate of energy loss from the binary pulsar
PSR1913+16 agrees with that predicted by the general relativistic quadrupole
formula to within 5%
