the Big Bang,
ang when
oduced the
nd.
1666 isaac newton formulates the law of gravity
and laws of motion, published in 1687.
pansion rate
also known
verse.
, the total mass-energy
sity. omega equal to 1
1900 max planck formulates the first description of quantum theory, which will eventually explain the nature of matter and energy on the subatomic scale.
sure of the (negative) ensity. an unvarying value osmological constant.
1917 albert einstein applies general relativity to
the universe. Later work by willem de sitter and
independently by aleksandr Friedmann implies the
possibility that the universe is expanding.
1924 edwin Hubble announces that the “spiral nebulae” sit beyond the milky way and later that the milky way is just one of many galaxies.
1 x 109 km
1929 Hubble finds that the universe is expanding,
after analyzing the redshifts of distant galaxies.
1933 Fritz Zwicky examines galaxies in the coma
cluster and determines that there is unseen mass,
what scientists call “dark matter.”
1960s steven weinberg, abdus salam and
sheldon glashow independently propose a theory to
unify electromagnetism and the weak nuclear force.
1 x 1018 km
1964 arno penzias and robert wilson discover the cosmic microwave background radiation; in 1990 nasa’s coBe mission confirms that the radiation’s properties verify the universe’s birth in a Big Bang.
1 x 1022 km
1986 astronomers margaret geller, John Huchra
and Valérie de Lapparent map a section of the
observable universe, revealing a structure that
encompasses large walls and giant voids.
1998 researchers discover that the universe is expanding at an accelerating rate, suggesting a mys- terious force dubbed “dark energy” might be at work.
4 x 1023 km
top, From LeFt: usgs, nasa eartH oBserVator Y; reto stÖcKLi and roBert simmon, modis/gsFc/nasa, usgs, dmsp; JpL-caLtecH/nasa, t. p YLe/ssc, adapted BY t. duBÉ; r. Hurt/ssc,
JpL-caLtecH/nasa; Bottom, From LeFt: daVid parKer/pHoto researcHers; nicoLLe rager FuLLer; nicoLLe rager FuLLer; taBLet: ViKtor gm Yria/ sHutterstocK.com
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april 23, 2011 | Science newS | 21
