NS101
2
The Big Bang: Origin of the Universe Before the universe as we now know it existed, there was no space or time. The Big Bang and its associated theories try to explain or describe the moment o f change from nothingness and no time to the existence of the universe filled with space and marked by time. Many physicists describe this event as an explosion, or flash, hence the name Big Bang. The Big Bang is a process of expansion in our universe that is still active toda y. The universe flashed into existence (according to the Big Bang theory) from a very small agglomeration o f matter of extremely high density and temperatures. s a dense, hot globule of gas, containing nothing but hydrogen and a small amount of helium, it began expanding rapidly outward. There were no stars or planets. The first stars probably formed when the universe was about !"" million years old. #ur $un was formed %.& billion years ago, and through telescopes we can now see stars forming out of compressed pockets of hydrogen in outer space. 'n ! instruments aboard the *osmic Background +xplorer (*#B+) satellite, launched in , showed that .- of the radiant energy of the universe was released within the first year of the Big Bang event. This evidence seems to confirm the Big Bang theory. 'n March & astronomers found more supporting evidence for the big bang when they concluded that data obtained from the space shuttle/s Astro 2 observatory showed that helium was widespread in the early universe. The Big Bang theory holds that hydrogen and helium were the first elements created when the universe was formed. The Steady Sate theory: 't states that the counting of the galaxies in our 0niverse is constant and new galaxies which are forming continuously are filling the empty spaces which are created by those heavenly bodies which have crossed the boundary lines of observable 0niverse. The Pulsating Theory: 'n this theory it is assumed that there is continuous expansion and contraction in universe. word which can replace the above definition is 12ulsating3. 2ulsating theory states that it is the possibility that after some passage of time the expansion in the universe may stop. Then their may be the possibility of contraction. 4hen this contraction will approaches to a particular si5e. gain the explosion will take place. s a result of this explosion the expansion of universe will start again. 6ence it results in a pulsating universe in which there is alternate expansion and contraction of universe. The Age and Composition of the Unive rse 'n one of the most important cosmological discoveries in years, 7$ scientists have captured the most precise image of the universe, shedding light on its origins, age, and providing further evidence for the long8standing Big Bang and inflation theories. 'n 9eb. !"":, a ;oint 7$<2rinceton 0niversity satellite, the 4ilkinson Microwave nisot ropic 2robe (4M2), produced a high8resolution map that cap tured the oldest light in the universe. This ancient light, called the cosmic microwave background, is the cooled remnant of the ho t explosion known as the Big Bang. =The cosmic microwave light is a fossil,> explained ?avid 4ilkinson, after whom the probe was named, =@ust as we can study dinosaur bones and reconstruct their lives of millions of years ago, we can probe this ancient light and reconstruct the universe as it was.> (4il kinson died ;ust before 4M2/s ama5ing findings were published.) The age of the universe ha s now been accurately determinedAwith ;ust a margin of errorAas :.- billion years old (previous estimates ranged between <!" billion years old). The birth of stars has been pinpointed to ;ust !"" million years after the Big Bang, a surpris e to most scientists (predictions had ranged from &"" milli on to billion years after the cosmos formed). The 4M2 image also revealed the contents of the u niverse only % is made up of atoms, or the physical universe as we know it. The re mainder is made up of poorly und erstood substances dark energy (-:) and dark matter (!:). These findings are consistent with the Big Bang and inflation theories, which assert that the universe materiali5ed in a =big ban g> and immediately began co oling and expanding. =' think every astronomer will remember where they were when they heard these results,> said @ohn Bahcall, a 2rinceton 0niversity astrophysicist. =' certainly will. This announcement represents a rite of passage for cosmology from speculation to precision science.>
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Transcript of NS101
7/18/2019 NS101
http://slidepdf.com/reader/full/ns101 1/2
The Big Bang: Origin of the Universe
Before the universe as we now know it existed, there was no space or time. The Big Bang and its associated
theories try to explain or describe the moment of change from nothingness and no time to the existence of the
universe filled with space and marked by time. Many physicists describe this event as an explosion, or flash,
hence the name Big Bang. The Big Bang is a process of expansion in our universe that is still active today.The universe flashed into existence (according to the Big Bang theory) from a very small agglomeration of
matter of extremely high density and temperatures. s a dense, hot globule of gas, containing nothing but
hydrogen and a small amount of helium, it began expanding rapidly outward. There were no stars or planets.The first stars probably formed when the universe was about !"" million years old. #ur $un was formed %.&
billion years ago, and through telescopes we can now see stars forming out of compressed pockets of hydrogen
in outer space.'n ! instruments aboard the *osmic Background +xplorer (*#B+) satellite, launched in , showed that
.- of the radiant energy of the universe was released within the first year of the Big Bang event. This
evidence seems to confirm the Big Bang theory. 'n March & astronomers found more supporting evidencefor the big bang when they concluded that data obtained from the space shuttle/s Astro 2 observatory showed
that helium was widespread in the early universe. The Big Bang theory holds that hydrogen and helium were the
first elements created when the universe was formed.
The Steady Sate theory: 't states that the counting of the galaxies in our 0niverse is constant and new galaxies
which are forming continuously are filling the empty spaces which are created by those heavenly bodies which
have crossed the boundary lines of observable 0niverse.
The Pulsating Theory: 'n this theory it is assumed that there is continuous expansion and contraction in
universe. word which can replace the above definition is 12ulsating3.
2ulsating theory states that it is the possibility that after some passage of time the expansion in the universe may
stop. Then their may be the possibility of contraction. 4hen this contraction will approaches to a particular si5e
gain the explosion will take place. s a result of this explosion the expansion of universe will start again.
6ence it results in a pulsating universe in which there is alternate expansion and contraction of universe.
The Age and Composition of the Universe
'n one of the most important cosmological discoveries in years, 7$ scientists have captured the most preciseimage of the universe, shedding light on its origins, age, and providing further evidence for the long8standing
Big Bang and inflation theories. 'n 9eb. !"":, a ;oint 7$<2rinceton 0niversity satellite, the 4ilkinson
Microwave nisotropic 2robe (4M2), produced a high8resolution map that captured the oldest light in theuniverse. This ancient light, called the cosmic microwave background, is the cooled remnant of the hot
explosion known as the Big Bang. =The cosmic microwave light is a fossil,> explained ?avid 4ilkinson, after
whom the probe was named, =@ust as we can study dinosaur bones and reconstruct their lives of millions ofyears ago, we can probe this ancient light and reconstruct the universe as it was.> (4ilkinson died ;ust before
4M2/s ama5ing findings were published.)
The age of the universe has now been accurately determinedAwith ;ust a margin of errorAas :.- billionyears old (previous estimates ranged between <!" billion years old). The birth of stars has been pinpointed to ;ust !"" million years after the Big Bang, a surprise to most scientists (predictions had ranged from &"" million
to billion years after the cosmos formed). The 4M2 image also revealed the contents of the universe only
% is made up of atoms, or the physical universe as we know it. The remainder is made up of poorly understoodsubstances dark energy (-:) and dark matter (!:). These findings are consistent with the Big Bang and
inflation theories, which assert that the universe materiali5ed in a =big bang> and immediately began cooling
and expanding. =' think every astronomer will remember where they were when they heard these results,> said
@ohn Bahcall, a 2rinceton 0niversity astrophysicist. =' certainly will. This announcement represents a rite of passage for cosmology from speculation to precision science.>
7/18/2019 NS101
http://slidepdf.com/reader/full/ns101 2/2
