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A comprehensive overview of the big bang theory, which is the prevailing cosmological model for the origin and evolution of the universe. It discusses the key concepts and evidence supporting the big bang theory, including the cosmic microwave background (cmb) radiation, hubble's law, and the expansion of the universe. The document also explores the role of dark matter and dark energy in the universe's evolution, as well as the ultimate fate of the universe. The information presented in this document could be useful for students studying topics related to cosmology, astrophysics, and the history of the universe.
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TARUN KUMAR LOT M.Sc.(PHYSICS) BHUMIKA KUMARI SUTHAR M.Sc. (PHYSICS)
The big bang theory predict and explains the origin of universe when t=0i.e. the time was not even exist .Or around 13.77 billion years ago. The prediction was thatan explosion occurs that was a singularity the explosion occurs which was the origin and expansion of universe. The universe is still expanding which can be seen by Hubble s law .However the scientists of 20 th^ century have taken so much of interest in cosmology and theoretical physics. When the time came into existence and its continuous further the fundamental particles also came into existence and when they cool down after millions of years they started to form stars ,planets , galaxies, supernova clusters etc. This theory becomesmore effective and famous after the discovery of cosmic microwave background radiation. (CMB).In the early expansion of universe (CMB) plays very crucial role to understand the origin of universe. when the universe was at its early stage before the formation of stars, planets, clusters etc. it was very hot and dense and also filled with a fog which radiates the waves of longer wavelength.When the temperature started cooling down and started to form hydrogen single proton atom 11 H which can also explain by Big bang nucleosynthieses and also by stellar nucleosynthesis. INTRODUCTION The curiosity to know about the celestial bodies and the origin of universe was not from this mid 19 thCentury basically it was from 5th^ century BC. The Babylonian civilization and further Ptolemy of 3 rdcentury AD started study about the heavenly bodies and as a result he discovered some planets and much more about the universe. The prediction of big bang was taken by Lemaitre which was related to cosmology. He has given his laws after seeing the work of Sir Albert Einstein on general theory of relativity and also Edwin Hubble work on cosmology and expansion of universe, further it was termed as Hubble law or Lemaitre law. Big Bang model also provides the exact explanation from the time of nucleosynthesis to till now. It also explain some concept that was mislead the scientist of early 19th^ and 20th^ century. Einstein in his general and special theory of relativity explains some of the unsolved questions regarding to the Big bang such as black hole, gravitational lensing, space time curve etc. As in his general theory of relativity Einstein has predicted that the universe is not flat it has a curve which relate to the space and time. He also explain that the light is deflected due to gravitational force of any heavenly body and bends even sir Albert Einstein has given an equation regarding origin of universe and it also help to understand the geometry of space time to the distribution of matter which was known as –Einstein field equation. Hubble’s law and Expansion of Universe As Edwin Hubble in his theory talked about expanding Universe, [1],[2],[3]He describes it with the galactic red shift and micro wave background radiation, although it was also explained with (SSS) model of Universe, i.e., Spherically symmetric model of Universe, rather than three Scientists of 20th Century Gives a model regarding to the universe e that was Freidman, Robertson Walker or (FRW) model of Universe.[4] It was good enough itself out when we relate this model to Einstein field equation not hold so good. The effective cause of that Leo Causes by Einstein General theory of relativity in the expansion of Universe. We can see it in our daily life. It was just happing around Universe in any part by it as the observable of Universe that weknow is about having distance of 46.5 billion light years or (8.8x 10^28 meters). Edwin Hubble He measure the rate of Expansion was a 73.84. (km/s) MPC after the CMB fluctuations it may changes to sol has 67.4+0. (km/s) MPC.
But In 2018, 2019, 2020 The larger change in has been observed by scientist of all over the world also by International Space Station, but After the CMB fluctuations it may changes to so has 67.4 (km/s) MPC. In 2018 Acc to the plank mission the lower value of 67.66 ± 0.42 km/h which in 2019 changes & Improved to 74.037 1.42 km/sec/ MPC which was taken by Hubble Telescope. In 2019 they The Scientist and astronomers have seen the Change in value of expansion. As In 1929 Edwin Hubble Explain that the Universe is expanding at a particular rate. As Hubble use Wavelength of light Coming from stars he uses the Red shift to calculate the expansion of universe e at that time. he describes the Relation between n Red- shift and distance That how red Shift can give us the rate of Expansion of universe by Hubble law.[5] V=HOD Where v = Recessional velocity (km/s) H = Hubble Constant, D =Proper distance which change relative to motion of Observer & galaxy it measures in mega Parsec (mph). As we know NASA has send his most promising telescope i.e. Hubble telescope on 24 April 1998. In our earth orbit later, it was merge with International Space Station. which was the most promising telescope of 90's which was made by NASA which having the mirror of 2.5 m from this telescope scientist can also measure the value of the rate of expansion of Universe. That was and also compare to the First measurement of expansion of universe which was taken by Edwin Hubble. Horizon – cosmological horizon plays very important Big-bang space time, since we know that the light which travels in universe has finite speed and and it as universe is expanding may be possible many of light waves are not reach to us. And it is also explain various properties of General theory of relativity. As recently NASA and ESA collaborate and send a Advance telescope that is Called James Web Telescope, which is Advance from Hubble Telescope, the images that taken by telescope was & shocked the whole world the image of early universe The Image was nearly about 13.1 billion years old, It means the light reaches from that Galaxy has taken 13.1 billon years to reach the earth. As this also shows that we need Horizon to understand the universe. Cosmological Horizon are of Many types like Particle Horizon Event Horizon Hubble horizon Practical Horizon Future horizon But the most promising horizon that also help us to understand the working of black hole, dark matter and dark energy is Event horizon, particle horizon and future Horizon. The cosmological horizon can distance object. However, an intriguing set of open Universe model shows an apparent entropy decreases when blackhole disappears over the cosmological event horizon.Even the model that was given by Freidman- Robertson-walker they Calculate some Challenging calculation to determine the Cosmological horizon. Event horizon - The best Example of Event horizon is Black hole the black hole having that much of gravity by which it can absorbs anything even light also. as we know light is deflect by the gravitational force which was explain successfully by Albert Einstein In
In a long period of time, equally distributed matter gravitationally attracts nearer matter and grew even dense They form gas clouds stars galaxies etc which can be see now.[11] FORMATION OF GALAXIES - As we know the largest astronomical Structure formed after big Bang so many galaxies are formed in Universe. There are mainly 4 types of Galaxies Spiral, barred Spiral, elliptical and irregular. Question always arises that how they are formed? The astrophysicists doesn’t have exact Idea about that and research was going on it, when the universe was 5000 years old Matter (proton, dark matter, helium etc) and when the universe started cooling down due to effect of gravitational force it started to make larger object .The dark matter of the Universe has such a large gravitational force. As a result, it attracts the baryon, helium, hydrogen and started to form stars, galaxiessupernova. And when the Universe, was 700 million years old the formation of stars have been started, and after 3 billion years the formation of solar System begins. There are two theories regarding formation of structure of Universe. But the most effective theories that was also seen by Hubble telescope, i.e. The formation on small clumps, and they merge to form a galaxies. CMB (Cosmic microwave Background ) The scientist and Astro physicist around the world started believing partially on the Big bang theory after Hubble law. But they are not completely agree to this theory They want some more strong evidence regarding big-bang and as a result Arno Penzais and Robert Wilson in 1964 discovered an Omni directional wave in. microwave band, which strongly supports and proof the prediction by Herman, Alphen and Gamow in 1950.[12] Cosmic microware background is the emission of black body energy which is coming from all the direction. CMB is the historical event of origin of Universe through big bang. In its early-stage universe was denser, hatter filled with heavy giant gas Clouds of Hydrogen plasma. Before formation of stars, Galaxies etc. and when once the Universe started Expands and Cooling down of plasma radiation filling it expands to longer wavelength, as opposite to plasma they cannot scatter in Thompson effect. so, the Universe become transparent The Precise measurement of CMB is very important to understand Cosmology. Because any of the theory regarding origin of universe Must have to Explain CMB. The temperature of CMB's when it has black body Radiation must be 2. 725 483+/-,0.0057. some more data which required to Understand the origin of universe through CMB Model like - Photon energy = 6.626x10-4^ having spectral radiance of 160.23 Ghz Relationship of CMB with big bang The Cosmic microwave background Radiation and Cosmological red shift distance seem goods enough evidence for Big- Bang if they are together, The measurement of (CMB) has represent the Inflationary Big bang as standard Cosmological model.[13] After the discovery of CMB in 1960 the scientist, [14]Cosmologist and astrophysicists + around the world has taken so much interest in it and have diminished interest in other alternative theory about the origin Universe like - Steady state theory, The CMB gives an idea about the picture of Universe at its early stage the electron and proton merge together and form Hydrogen atom when the temperature dropped. When the temperature of Universe was 3000 K approximately 380000 years after the big bang that time is also known as "Time of last scattering” The energy at that time was only 0.26 eve which is very less than the energy of Hydrogen i.e. 13.06 eve.[15][16] As we consider as standard ionization energy & after decoupling due to expansion of universe. Color temperature of CMB radiation has decreased by on average factor of 1090. [17]
Cosmic Acceleration – As Edwin Hubble Explain about expansion of Universe. As it is moving, so it has a acceleration also. As we can see in (CMB) The dark energy can be seen in it. Which is regards to whole universe. Some scientist observed that 73% of the total energy density is dark energy. As in early stage of Universe the Stars, galaxies, etc have less space between Them and so the gravitational force was very strong between them but eventually after billion of years when universe expansion And as a result the density of matter decreases w.r.t density of dark energy due to this universe started to accelerate slowly.[18] Even Einstein in his general theory of Relativity uses dark energy as a Cosmological Constant which can be seen in Einstein field equation. The Evidence of Cosmic acceleration was discovered in 1998. by two projects named supernova cosmology project and High Z- Supernova. In these projects scientist have observed that the object in universe are moving far away from each other, this proof show the Evidence of Big-bang and also Hubble has given in his observation after that the scientist of each group have been awarded by Noble Prize.
. Some issue that cannot be resolved by Big Bang theory in Physics Dark Energy - As we know that Universe in Expanding and accelerating at very fast speed. Acc to general theory of Relativity of Sir Albert Einstein, we need an Term to defined the acceleration of expansion of Universe so we termed it as "Dark Energy" The dark Energy also help to solve flatness problem of Universe acc to CMB the universe is flat and also me general relativity Universe mast have, critical mass or Energy But we found only of 30% of the critical density. The team of WMAP found that the observable universe Consist of 71.4 % of Dark Energy 24% of Dark Matter , & 4.6.% of atoms.[19] But according to the theory there will be an decrement in dark energy as Universe expands. Even Einstein also added and Cosmological Constant to solve the Problem of Dark Energy Accurately But till me don't have exact Constant to explain the dark Energy. Experimental Evidences Supernovas Cosmic microwave Background Sachs- Wolfe effect Dark Matter In 70 s and 80 s , some observation shows that there is no exact matter which can explain Apparent strength of the gravitational force between the galaxies and other Cluster It does not interact it with light which make it more difficult to detect. The scientists named .Ken freeman, Kent ford and Vera Rubin in 1960 & 70's provided some evidences regarding dark matter. They use spectrograph to measure the velocity of edge on-spiral galaxy accurately They have showed that the most of the galaxies must contain six times as much dark as visible mass. Observational Evidences regarding Dark matter First evidence that supports the existence of dark matter is like that it affect the speed of Celestial
Big Bounce - This is an another hypothetical model which also gives an idea about End of Universe Basically the base of this hypothesis is on Cyclic Model or Oscillatory Universe Model about beginning. The postulation of big - bounce seems to be the big bang as the beginning of it and which is after the contraction period This theory was purposed by assistant Professor of Physics at Penn state institute of Gravitational Physics and Geometry. He has taken help from Einstein’s General theory of Relativity and equation of quantum Mechanics and merges them to made an mathematical description of the Creation of Universe’. Big-bang cannot explain the end of universe. As Big Bounce tells us that the universe will expand and again it will Contract. As gravitational force been the galaxies and due external velocity from big bang and when it will reaches to its maximum expansion even gravitational force between Clusters Galaxies etc will not work. it will again start to Contract and it will become the reason for Big - Crunch, and it will again repeat is the form of big bang ..
1965). "A Measurement of Excess Antenna Temperature at 4080 Mc/s". The Astrophysical Journal. 142 : 419–