Insights into Cosmology: From Static Universe to Big Bang Theory
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Explore the evolution of cosmological theories from a static universe concept to the groundbreaking Big Bang theory, including key figures and discoveries in the field. This comprehensive overview delves into the history and implications of our expanding universe.
Insights into Cosmology: From Static Universe to Big Bang Theory
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(A few) BasicTopicalConceptsin Cosmology EmiliElizalde Institut de Ciències de l’Espai (ICE/CSIC) Institutd’EstudisEspacials de Catalunya (IEEC) Campus UniversitatAutònoma de Barcelona (UAB) Bellaterra Lunch-Pizza Seminar, 16 March2012
But... the Universe was static !! (…and very small) • Whatisλ ? Non-physical • At that time: UNIVERSE = MILKY WAY (+ nebulae) • Ptolemy 150 DC, Almagest:mentions5nebulae • Persian, Arabic, Chinese astronomers: more nebulae • Edmund Halley 6 in 1715, Charles Messier103 in 1781 William and Caroline Herschel 3 catalogs, 1786-1802, a total of 2510 nebulae • And then, Edwin Hubble, in 1922-1924, saw Andromeda nebulae (.8 Mly) was far beyond our Milky Way: nebulae were other galaxies! • Henrietta S Leavitt(EdPickering’s Harvard Harem), ‘12 period-luminosityrelationshipof Cepheid variable stars (Eddington , He+,++) Hertzsprung-RussellDiagramm
Henrietta Leavitt Mittag-Leffler NP proposal ‘26 Ed Pickering’s Harvard Harem 1913 … or Harvard Computers
Karl Schwarzschild: Black Holesolution (22 Dec 1915) • Willem de Sitter: masslessuniverstatic sol (just cc,’17) • Alexander Friedmann: expandinguniverse sol (1922) • Georges Lemaître: expanding universe (MIT 1925, AF solution); visited VestoSlipher(Lowell Obs, Arizona, 1912 redshifts) and Edwin Hubble(Mount Wilson, Pasadena); Keeler-Slipher-Campbell, 1918 • Led to Big Bang theory (Fred Hoyle, BBC radio 3rdProgramme, 18:30 GMT, 28 March 1949) • Fred Hoyle, Thomas Gold, Hermann Bondi:SteadyState ’48, “C-field” with a negative pressure, to be consistent with energy conservation (anticipatedinflation) • Friedmann-Lemaître-Robertson-Walker (FLRW 1931-37) • A Riess B Schmidt ’98, SPerlmutter ’99: accelerexpan!
Multiply by a2 to get When a increases, each term on rhs decreases: the universe should be decelerating (a decreases) . Friedmann equation (matter,radiation,curvature) a Sean Carroll, Caltech SSI 2009 Big Bang t
Two groups looked for the ‘deceleration’ of the universe expansion, using type Ia supernovae as standardizable candles SN 1994d
Result:supernovae are dimmer than expected The universe is not decelerating It is accelerating Cannot be explained by matter+radiation (see before) Riess, Schmidt et al. ‘98 Perlmutter et al. ‘99
SomeBooks 2nd Ed June 2012