# Century Timeline

# Appendix A: Examples of key historic events, organized by Cosmic Times themes

**Expansion of the Universe/Nature of the Universe**

1915 -- General Relativity published

1926 -- Albert Einstein predicts bending of light

1919 -- Solar eclipse confirms Einstein's Theory of Gravity

1917 -- Einstein's Cosmological Constant

1912 -- Vesto Slipher measures spectral lines in spiral nebulae to be
redshifted.

Theories of expanding Universe based on Einstein's General Relativity by

> 1932-- DeSitter
>
> 1922--Friedman
>
> 1927--Lamaitre

1929 -- Edwin Hubble shows universe is expanding; Einstein's
Cosmological constant thrown out.

1949 -- Ralph Alpher and Robert Herman reworked George Gamow's ideas of
early universe and predict relict a primordial radiation in microwave
range (i.e. the cosmic microwave background, CMB).

1950 -- Fred Hoyle scoffs at evolutionary theory of universe and calls
it a "Big Bang"

1961 -- Edward Ohm finds microwave remnant, does not recognize it as
important.

1965 -- Arno Penzias and Robert Wilson discover CMB

1967 -- astrophysicists Martin Rees and Dennis Sciama predict deviations
in CMB

1967 -- Integrated Sachs-Wolfe effect described

1970 -- Vera Rubin makes a case for dark matter

1981 -- Alan Guth proposes cosmic inflation to solve isotropy/smoothness
problem in big bang

1989 -- Cosmic Background Explorer (COBE) launched

1990 -- ROSAT launched

1990 -- COBE measures CMB Spectrum as blackbody

1992 -- COBE measures fluctuations and anisotropy in the CMB.

1993 -- ROSAT mission detects dark matter that is 30 times more
prevalent than visible matter.

1998 -- detection of gravity defying dark energy

**Size of the Universe**

1912 -- Henrietta Leavitt describes the Cepheid variable
period-luminosity relationship

1912 -- Discovery of redshift of galaxies by Vesto Slipher

1918 and 1919 -- Harlow Shapley estimates Milky Way at 300 000 light
years, using Leavitt's discoveries.

1920 -- Harlow Shapley and Heber Curtis debate the nature of the "spiral
nebulae"

1929 -- Furthest galaxy detected is 70 million light years away, making
universe at least 140 million light years in size

1952 -- Walter Baade-- discovers there are two populations of Cepheids
so he recalculates distance to Andromeda and finds it is twice as far as
thought or 1.8 billion l.y.

1955 -- Furthest galaxies detected are 2-4 billion light years away,
making universe 4-8 billion light years in size.

1960's -- Discovery of Quasars doubles size of universe

1960 -- found 3C 48 and 1963 -- found 3C 273

1965 -- Furthest quasars are about 13 billion light years away, making
universe about 25 Billion light years in size.

1993 -- Most distant radio galaxy is about 15 billion light years away,
making the universe about 30 billion light years in size.

2006 -- Farthest galaxies now indicate a size of the universe at about
90 billion light years.

**Nature of Supernova**

1934 -- Walter Baade and Fritz Zwicky coin the term "super-nova"

1941 -- Rudolph Minkowski finds difference between Type I and Type II
supernova

1993 -- M. Phillips proposes Type Ia Supernovae as standard candles

1998 -- Type Ia supernova measure acceleration of expansion of universe
and conclude dark energy component to universe

2013 -- prospective launch date Joint Dark Energy Mission

**Miscellaneous**

1908 -- 60 inch Hale telescope at Mount Wilson.

Early1900's -- "Pickering's Harem" of Women computers at Harvard College
Observatory

1917 -- 100 inch Hooker Reflector at Mount Wilson

1929 -- Milton Humason teams with Edwin Hubble

1948 -- 200 inch Mount Palomar

1952 -- Radio Source discovered in the constellation Cygnus

1955 -- Einstein's Death

1974 -- Princeton University astronomers Russell A. Hulse and Joseph H.
Taylor located pulsar 1913 +16

1993 -- Hulse and Taylor win Nobel prize for binary pulsar

2003 -- WMAP confirms dark matter and dark energy

2006 -- Astrophysicists John Mather and George Smoot awarded the Nobel
Prize in Physics