Terms of ReferenceI wrote this Report specially for ourstudents , because many of us have a little information about this importanttheory , this Report was written according to many scientific theory and Researchwithout any self opinion.
As far as iam concerned this report may not offer a properinformation about this topic but somehow it can help students to get a bit moreinformation about it , so I hope to heat my target which is helping students toget more experience .Abstract ( Summary)The Big Bang Theory is a cosmologicaltheory explains that how universe began from a very small point , The aim ofthis Report is to describe and explain Big Bang theory, and the aim of theTheory is to observe that all matter and universe was concentrated in a small pointbefore 13.7 billion years ago, and then began to expansion with a hot explosionand till today the universe expanding without any limit , one of the mostimportant points that needs to be mentioned is , this Theory isn’t a religioustopic but it’s a collection of too many researches that were worked on by a plenty of scientistsand it became a scientific theory . ContentsTerms of Reference 1Abstract ( Summary ) 1Content 1-2- Introduction 2-Report Body 3-8 What happen inthe first second after the universe began ? 3-4 Expansion of universe 4-5 Features of models 6did all the scientist support Big bang theory ? 6-7 How old is the universe ? 7- Conclusion 7-8- Reference List 8- Appendices 8-10 Introduction Along the history humans always have a somequestions about the beginning of the universe include : How did our universebegin? How old is our universe? How did matter come to exist? Obviously, theseare not ordinary questions and throughout our brief history on this planet muchtime and effort has been spent looking for some clue. Yet, after all this energyhas been expended, much of what we know is still only speculation.
But Big BangTheory can help us to understand our Universe . Today,the consensus among scientists, astronomers and cosmologists is that theUniverse as we know it was created in a very big explosion,Big Bang Theory is the most importantcosmological Theory that wants to explain what happened at the very beginningof the universe, and wants to observe that our universe have a beginning , The basics of thetheory are very simple. In brief , the Big Bang hypothesis states that all ofthe current and past matter in the Universe came into existence at the sametime, roughly 13.8 billion years ago. At this time, all matter was compactedinto a very small ball with infinite density and intense heat called aSingularity. Suddenly, the Singularity began expanding, and the universe as weknow it began . seriously this theory does not observe everything like (DarkEnergy) and till now the scientist can not explain completely what is Dark Matter , and also some ofscientist do not believe and do not support this Theory and some of them havean alternative , this Theory is still developing and till now the research arecontinuing .
Report BodyOne of the most continuingasked questions has been: How was the universe created? Many once believed thatthe universe had no beginning or end . but Big Bang Theory refused this ideacompletely and emphasized that Universe has a beginning and an end . Regarding to Big Bang Theory , At thebeginning the whole universe was just a small point that had an extreme hightemperature and high density , but at about 13.7 billion years ago the universe begun to expansion with ahot explosion.What happened in the firstsecond after the universe began ? In the firstsecond after the universe began, the temperature was nearly 10 billion degreesFahrenheit (5.
5 billion Celsius) ,The cosmos consisted of a wide array offundamental particles for instance , neutrons , electrons and protons. Thesedecayed or combined as the universe got cooler. But imagine that light could not carry inside of it , how can you look at it ?After the initial expansion the universecooled sufficiently to allow the formation of subatomic particles, and latersimple atoms , these primordial elements later coalesced through gravity in halos of dark matter , ongoing forming the stars and galaxiesobvious today . “The free electrons would have caused light(photons) to scatter the way sunlight scatters from the water droplets inclouds” Over time, however, the free electrons met up with nuclei andcreated neutral atoms . This allowed light to shine through about 380,000 yearsafter the Big Bang.
This light is known as (after glow)ofthe big bang.CoolingThe universe continued to minimize in densityand fall in temperature , hence the typical energy of each particle wasdecreasing . Symmetrybreaking phasetransitions put the fundamental forces of physics and the parameters of elementary particles into their exist form.
After about 10?11 seconds, the picture turns to less speculative,since particle energies drop to values that can be attained in particle accelerators. At about 10?6 seconds,quarks and gluons combined to form baryons such as protons and neutrons. The smallexcess of quarks over antiquarks led to a small excess of baryons overantibaryons. The temperature was now no longer high enough to create newproton–antiproton pairs (similarly for neutrons–antineutrons) , so a mass annihilationsuddenly followed, leaving just one in 1010 of the originalprotons and neutrons, and none of their antiparticles.
A similar process occurredat about 1 second for electrons and positrons. After these annihilations, the leftprotons, neutrons and electrons were no longer moving relativistically and theenergy density of the universe was dominated by photons (with a minor contribution from neutrinos).A few minutes into the expansion, when thetemperature was about a billion (one thousand million) kelvin and the density was about that of air , neutronscombined with protons to form the universe’s deuterium and helium nuclei in a process called Big Bangnucleosynthesis. Mostprotons remained uncombined as hydrogen nuclei. As the universe cooled, the rest mass energy density of matter came togravitationally dominate that of the photon radiation . After nearly 379,000years , the electrons and nuclei combined into atoms (mostly hydrogen); hencethe radiation decoupled from matter and continued through space gratelyunimpeded .
This relic radiation is known as the cosmicmicrowave background radiation . The chemistry of life may have begun shortly after the BigBang , 13.8 billion years ago, during a habitable epochwhen the universe was just 10–17 million years old. Expansion of universeDarkenergy is even more mysterious, and its discovery in the 1990s was a complete surpriseto scientists. Previously, physicists had assumed that the beauty force ofgravity would slow down the expansion of the universe over time. But when twoindependent teams tried to measure the rate of deceleration, they found thatthe expansion was definitely speeding up.OurUniversity contains of 3 basic types ofmatter ( Dark Energy , Dark Matter , Ordinary Matter )What is Dark Energy ?More is unknown than is known .
We knowhow much dark energy there is because we know how it affects the universe’sexpansion. Other than that , it is a complete mystery . But it is an importantmystery . It turns out that almost 68% of theuniverse is dark energy . One explanation for dark energy is that it is aproperty of space. Albert Einstein was the first person to identify that emptyspace is not nothing.
Space has wonderful characteristic , many of which arejust beginning to be understood. The first property that Einstein found is thatit is suitable for more space to come into existence . Then one version ofEinstein’s gravity theory , the version that contains a cosmologicalconstant , makes asecond prediction: “empty space” can possess its own energy. Becausethis energy is a property of space itself , it would not be diluted as spaceexpands .
As more space comes into existence, more of this energy-of-space wouldappear , As a result, this form of energy could cause the universe to expandfaster and faster.What is Dark MatterWe are muchmore certain what dark matter is not than we are what it is . First, it is dark, meaning that it is not in the form of stars and planets that we can see .
noticesshow that there is far too little visible matter in the universe to make up the27% required by the observations . Second , it is not in the form of darkclouds of normal matter , matter made up of particles called baryons. We knowthis because we would be able to detect baryonic clouds by their absorption ofradiation passing through them . Third, dark matter is not antimatter , becausewe do not see the unique gamma rays that are produced when antimatterannihilates with matter.
In all in ,the continuous expansion of Universe is totally because two primary things ,Dark Energy and Dark Matter.What isOrdinary Matter ?look at the sky at night what do you see ? stars , planets and all other kind of Mattersin the Universe are known as Ordinary matter .Features of the modelTheBig Bang theory relays on two main assumptions: the universality of physicallaws and the cosmological principle . The cosmological principle states that on large scalesthe universe is homogeneous and isotropic.
Theseviews were initially taken as postulates , but today there are efforts to testeach of them . For example , the first assumption has been tested byobservations showing that largest possible deviation of the fine structure constant over much of the age of the universe isof order 10?5. Also , general relativity has passed stringent tests on the scale of the Solar System and binary stars. Ifthe large-scale universe appears isotropic as viewed from Earth , thecosmological principle can be derived from the simpler Copernican principle , which states that there is no preferred (or special)observer or vantage point.
To this end , the cosmological principle has been approvedto a level of 10?5 via observations of the CMB. The universehas been measured to be homogeneous on the biggest scales at the 10% level. did all the scientists support Big bang theory?Of course no ,in 1948 British scientists , Sir Hermann Bondi, Thomas Gold, and Sir Fred Hoyle . presented anew theory , in their opinion this couldbe as an alternative to Big Bang theory which named (Steady State Theory).What is SteadyState Theory ?In cosmology, the Steady Statetheory is an alternative to the Big Bang model of the evolution of our universe. In the 1940s Sir Fred Hoyle and others developed an alternativemathematical model of the Universe that did not begin in a large expansion .
Theysaid that matter is eventually created at a rate that keeps the average densityof the Universe the same as it expands . Though the Steady State theorists’ideas are largely discredited today , their research pushed the Big Bangsupporters to back up their theory with evidence.amazingly , it wasHoyle who coined the term Big Bang in an attempt to put down the idea that theUniverse had a beginning . According to theSteady State Theory , one of its items which is fully against the Theory of BigBang is that Universe has neither a beginning of its creation nor a deadline How old is the universeAgemay only be a number, but when it comes to the age of the universe , it’s apretty important one . According to research , the universe is approximately13.
8 billion years old . How did scientists determine how many candles to puton the universe’s birthday cake ? They can determine the age of the universeusing two different forms : by studying the oldest subject within the universeand measuring how fast it is expanding.Conclusion Nowwe understood that our universe was came from a small singularity which have anextreme high temperature and density and then , and immediately before 13.8billion years the universe faced an explosion , after this great explosion theuniverse started cooling , and expanding .TheUniverse is contain of (Dark Energy , Dark Matter , Normal Matter) 68% ofour University is Dark Energy that caused the Universe to expand27%of our Universe is Dark Matter , which is not in the same form starsand planets that we see5% of our University is normal matter ,such as stars and planets and all kind of Matter that we can see and describenormally . And Big Bang is not only Theory of howthe universe came from begin for example, there is the Steady StateTheory . Reference List1- ( The Theory of everything ) StephenHawking 2- www.space.
com 6- https://www.youtube.com/watch?v=R55rP3K-IbMAppendicesResult The big bang theory is vastly acceptedbecause there is strong evidence in its favour, and because it arises naturallyfrom the General Theory of Relativity , which is itself a well-tested theory .There have been several alternative models since the Big Bang was proposed inthe late 1940s, but most of them failed observational tests. There is onecurrently supported alternative theory , which is more hard to test , butrelevant evidence should be forthcoming in the subsequent few years.
What are themajor clue which support the Big Bang theory? First of all, we are reasonably certain that the universe had a beginning. Second , galaxies appear to be moving away from us at speeds proportional to their distance . This is called “Hubble’s Law,” named after Edwin Hubble (1889-1953) who discovered this phenomenon in 1929. This observation gets behind the expansion of the universe and suggests that the universe was once compacted. Third , if the universe was initially very, very hot as the Big Bang suggests , we should be able to find some remnant of this heat . In 1965, Radio astronomers Arno Penzias and Robert Wilson discovered a 2.
725 degree Kelvin (-454.765 degree Fahrenheit , -270.425 degree Celsius) Cosmic Microwave Background radiation (CMB) which pervades the observable universe. This is thought to be the remnant which scientists were searching for. Penzias and Wilson shared in the 1978 Nobel Prize for Physics for their discovery.
Finally , the abundance of the “light elements” Hydrogen and Helium found in the observable universe are thought to support the Big Bang model of origins.