Big Bang
hideThe Big Bang is the cosmological model of the initial conditions and subsequent development of the universe that is supported by the most comprehensive and accurate explanations from current scientific evidence and observation. As used by cosmologists, the term Big Bang generally refers to the idea that the universe has expanded from a primordial hot and dense initial condition at some finite time in the past, and continues to expand to this day.
Georges Lemaître proposed what became known as the Big Bang theory of the origin of the Universe, although he called it his "hypothesis of the primeval atom". The framework for the model relies on Albert Einstein's general relativity and on simplifying assumptions (such as homogeneity and isotropy of space). The governing equations had been formulated by Alexander Friedmann. After Edwin Hubble discovered in 1929 that the distances to far away galaxies were generally proportional to their redshifts, as suggested by Lemaître in 1927, this observation was taken to indicate that all very distant galaxies and clusters have an apparent velocity directly away from our vantage point: the farther away, the higher the apparent velocity. If the distance between galaxy clusters is increasing today, everything must have been closer together in the past. This idea has been considered in detail back in time to extreme densities and temperatures, and large particle accelerators have been built to experiment on and test such conditions, resulting in significant confirmation of the theory, but these accelerators have limited capabilities to probe into such high energy regimes. Without any evidence associated with the earliest instant of the expansion, the Big Bang theory cannot and does not provide any explanation for such an initial condition; rather, it describes and explains the general evolution of the universe since that instant. The observed abundances of the light elements throughout the cosmos closely match the calculated predictions for the formation of these elements from nuclear processes in the rapidly expanding and cooling first minutes of the universe, as logically and quantitatively detailed according to Big Bang nucleosynthesis.
Fred Hoyle is credited with coining the term Big Bang during a 1949 radio broadcast. It is popularly reported that Hoyle intended this to be pejorative, but Hoyle explicitly denied this and said it was just a striking image meant to emphasize the difference between the two theories for radio listeners. Hoyle later helped considerably in the effort to understand stellar nucleosynthesis, the nuclear pathway for building certain heavier elements from lighter ones. After the discovery of the cosmic microwave background radiation in 1964, and especially when its spectrum (i.e., the amount of radiation measured at each wavelength) sketched out a blackbody curve, most scientists were fairly convinced by the evidence that some Big Bang scenario must have occurred.
For more information about Big Bang, read the full article at
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News tagged with big bang
COBE Satellite Marks 20th Anniversary
Space & Earth / Space Exploration
Nov 17, 2009 |
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(PhysOrg.com) -- NASA's Cosmic Background Explorer (COBE) satellite rocketed into Earth orbit on Nov. 18, 1989, and quickly revolutionized our understanding of the early cosmos. Developed and built at Goddard ...
'Dropouts' pinpoint earliest galaxies
Nov 06, 2009 |
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Astronomers, conducting the broadest survey to date of galaxies from about 800 million years after the Big Bang, have found 22 early galaxies and confirmed the age of one by its characteristic hydrogen signature ...
Dark matter sleuths to design world's largest WIMP catcher
Oct 29, 2009 |
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A team of researchers led by a Case Western Reserve University physicist is planning the world's largest, most sensitive experiment to catch the stuff of dark matter, stuff that's proved way beyond invisible.
Astronomers explore 'last blank space' on map of the Universe
Oct 28, 2009 |
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(PhysOrg.com) -- The most distant object ever discovered is described in this week's edition of the science journal Nature. Two international teams of astronomers report their observations of a gamma-ray burst ...
Physicists Calculate Number of Parallel Universes
Oct 16, 2009 |
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(PhysOrg.com) -- Over the past few decades, the idea that our universe could be one of many alternate universes within a giant multiverse has grown from a sci-fi fantasy into a legitimate theoretical possibility. ...
Has PAMELA Already Seen Dark Matter?
Aug 25, 2009 |
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(PhysOrg.com) -- Back in 2006, PAMELA (a Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) was launched with the purpose of detecting cosmic radiation and looking for clues pointing ...
'Big crunch' or another 'Big Bang?'
Aug 16, 2009 |
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Will the universe expand outward for all of eternity and end in a vast, dark, cold, sterile, diffuse nothingness? Or will the “Big Bang” — the gargantuan explosion that formed the universe 14 billion years ...
Planck Sees Light Billions of Years Old
Aug 14, 2009 |
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The Planck space telescope has begun to collect light left over from the Big Bang explosion that created our universe.
The cosmic comic: Riding early waves
Space & Earth / Space Exploration
Aug 05, 2009 |
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(PhysOrg.com) -- Fundamental research in cosmology continues to disclose ever more mysteries of the first millennia of the universe. More detailed knowledge will be delivered by the recently launched Planck ...
Restart of Large Hadron Collider now November
Jul 30, 2009 |
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(AP) -- Repairs to two small helium leaks in the world's largest atom smasher will delay the restart of the giant machine another month until November, a spokesman for the operator said Thursday.
QUIET team to deploy new gravity-wave probe in June
May 15, 2009 |
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A tiny fraction of a second following the big bang, the universe allegedly experienced the most inflationary period it has ever known.
Austria to pull out of European CERN institute
May 07, 2009 |
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Austria is pulling out of the European Organisation for Nuclear Research (CERN), Science Minister Johannes Hahn announced Thursday, citing budget concerns.
Europe is about to take an astronomical lead over U.S.
May 07, 2009 |
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The world's astronomers are about to get a trio of powerful new eyes on the sky that can see better and farther than existing space telescopes.
Super-Sensors to Measure 'Signature' of Inflationary Universe (w/Video)
May 03, 2009 |
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What happened in the first trillionth of a trillionth of a trillionth of a second after the Big Bang? Super-sensitive microwave detectors, built at the National Institute of Standards and Technology, may soon ...
Discovery poses challenge to galaxy formation theories
Apr 10, 2009 |
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A team led by an Indiana University astronomer has found a sample of massive galaxies with properties that suggest that they may have formed relatively recently. This would run counter to the widely-held belief ...
