PoS(ICRC2015)511

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The microwave sufficiently for sufficiently age of the universe over the sky (apart over sky the 5 as propagated freely ever since, since, ever freely as propagated he expansion of the Universe. Universe. of the expansion he ______H. From this time onwards, cosmic cosmic onwards, this time From H.

in temperature only aby partsfew in 10 yet to beyet detected. ground originated the when universe was denser by a eculiar motion through the microwave background’s r diation becomes a useful astronomical data source. . The. radiationprovides the distantmost direct im 4 Introduction [email protected] and younger by a factor of around 5× 10 9 radiation was effectively unable to interact with the background gas; it h it gas; background the interact with to unable effectively was radiation t by is stretched because its wavelength energy losing constantly while electrons and protons to combine into hydrogen atoms, p + e atoms, hydrogen into to combine and protons electrons About 380,000 years after the Big Bang, the temperature of the Universe had dropped had Universe the of temperature the Bang, Big the after years 380,000 About ______Adventures in Inflation And Cosmic Microwave Microwave Cosmic Inflation And in Adventures cosmos. the of Thefuture - Background Rashmi Ramesh SSN College of Engineering Chennai, India E-mail: The radiation present astoday a 2.7 back K thermal 10 we canwe hope to see, at least until gravitational ra background radiation extremely is uniform, varying from an overallan from dipole variation arising ourfrom p departureits afrom perfect blackbody spectrum has The 34th International Cosmic Ray Conference 30 July-6 August, 2015 The Hague, The Netherlands • PoS(ICRC2015)511 he diagram to the diagram he c and direct and direct c ow us to determine the the to determine us ow of the cosmic microwave microwave cosmic the of background have been been have background reas today it has fallen to only to only it fallen has today reas nt-size is greater than the the than greater is nt-size buted throughout the Universe the Universe throughout buted tance of about a million billion billion a million about of tance ion is measured as a function of the the of a function as ision measured rse at a very early stage on what is is on what stage early a very at rse ensity. The theoretical best fit curve (the (the curve fit best theoretical The ensity.

The Temperature of the universe today universe the of Temperature The

3K. thesee Unive to are able today radiation this detecting Observers microwave cosmic the Photons in last scattering'. of as the 'surface known a dis covered and have years, billion ten over for us towards travelling miles. billion Originally, the radiation temperature was about 3000 degrees Kelvin, whe Kelvin, degrees 3000 about was temperature radiation the Originally, temperature of the Universe today. The brightness of the relic radiat relic the of brightness The today. the Universe of temperature distri radiation thermal by described is approximately It frequency. radio This a dramati is zero. absolute above 2.735 degrees about of temperature with a model. Bang Big Hot the of predictions the of of one confirmation spectrum the measured satellite (COBE) Explorer Background Cosmic The T and experiment. theory between agreement remarkable showing in 1990, background int versus centimeter per in waves plotted results the right shows poi (the points data the experimental from indistinguishable is solid line) errors). experimental Measurements of the cosmic microwave background radiation (CMB) all (CMB) radiation background microwave cosmic the of Measurements • • PoS(ICRC2015)511 mic mic ations and a pples at the edge of the edge at pples ighly uniform in every in every uniform ighly ections projected onto a onto projected ections ears after the Big Bang. These These Bang. the Big after ears kground radiation in 1964. In In 1964. in radiation kground neque. The COBE satellite was was satellite The COBE neque. t COBE obtained. They are at the level the are at They obtained. t COBE

asymmetry due to our motion with respect to costhe he velocityhe contribution, showing primordial fluctu alaxy (the horizontal strip).

Ripples At The Edge Of The Universe Universe The Of Edge The At Ripples

The temperature fluctuations after subtraction of t The temperatureraw (top)map a has large diagonal large radio from signal nearby sourcesour in own g microwave background a - Doppler shift. 2. 1. launched twenty five years after the discovery of the microwave bac microwave of the theafter discovery years five twenty launched 'ri had discovered they that announces team the COBE in 1992, fashion spectacular y 380,000 at fluctuations of primordial sign first the is, that the Universe', formation. of galaxy seeds the of imprint theare tha picture sky full the on variations temperature as appear These is h the Universe reverse in Viewed thousand. hundred in one one part of only principle. cosmological the for support strong lending direction dir in all the Universe of temperature below shows the image thumbprint The earth): of the a map to (similar plane Suspendisse lectus leo, consectetur in tempor sit amet, placerat quis placerat sit amet, in tempor consectetur leo, lectus Suspendisse • • PoS(ICRC2015)511 e. The photons are are e. photons The eral important eral important ly fast for a fraction of a of a fraction a fast for ly Universe and travelled and Universe strings are quite similar, similar, quite are strings he time required to send send required to time he ategories: (1) causal (1) ategories: hese two photons exchange exchange photons two hese structure and the fluctuations fluctuations and the structure o was released at the same time, time, same the at released o was flationary scenarios. scenarios. flationary ts between these different models. models. different these between ts hey create are shown below for for below shown are create hey . Assume, for a moment, the a moment, for . Assume, imental improvements in the study study the in improvements imental horizon problem horizon e galaxy signal.

The Inflatory Universe Universe Inflatory The The Origin Of Fluctuations In The CMB CMB In The Fluctuations Of Origin The

The primordial fluctuations after subtraction of th 3. exponential expanded Universe early the of inflation, theory the to According second after the Big Bang. Cosmologists introduced this idea in 1981 to solve sev solve to in 1981 idea this introduced Cosmologists Bang. Big the after second is the One problems these of in cosmology. problems There are a variety of competing theories for the origin of large-scale of origin the for theories of competing a variety are There c two into fall models These radiation. background microwave cosmic in the in(2)or textures, and strings cosmic such as models, defect topological t that patterns fluctuation microwave cosmic different the of Examples and cosmic models inflationary of features random The degrees. of a few maps Exper defects. for other features stronger the from distinct quite being tes to discriminating lead should fluctuations scale CMB small of such Universe is not expanding. Now imagine a photo was released very early in the in early very released a photo was imagine Now is expanding. not Universe phot another imagine Now Earth. the Pole of the North hits it until freely t Could Pole. South the at Earth the will hit It one. first the to "opposite" but t because not, Clearly are they released? when the time from information any Univers the of the age times two be would to other the one photo from information horizon. other's each of are outside They disconnected. causally • • • • PoS(ICRC2015)511 ic early ehow, ehow, nsion, as all all as nsion, almost exactly) the the exactly) almost actually very close very actually expanded by a factor of of a factor by expanded croscope that magnifies croscope magnifies that same temperature in all in all temperature same regions) and in the in and regions) on of the balloon. A person at at person A balloon. the on of beginning of inflation. The of inflation. beginning se could have been in causal contact contact causal in been have could se exponentially for a short time period period time short for a exponentially cm, to cosmological distances. This leaves This distances. to cosmological cm, -28 expanded other unless inflation took place during the very

. This number is a one followed by 26 zeros. It transcends normal political/econom normal transcends It 26 zeros. by followed a one is This number . 26 =10 60 Quantum Fluctuations Fluctuations Quantum imprints in the cosmic microwave background radiation (hotter and colder and (hotter radiation background microwave cosmic the in imprints of galaxies distribution discussions of inflation. inflation. of discussions

We are able to observe quantum fluctuations that were created at the at were created that fluctuations quantum observe to able are We expansion of the Universe during the inflationary epoch serves as a huge mi huge as a serves epoch inflationary the during the Universe of expansion 10 than less to a scale corresponding fluctuations, quantum These photons could not havecommunicated with each Universe. som communicated have must opposite directions from photons that observe we However, the exactly almost has radiation background microwave the cosmic because sky. the over directions Universe the that the idea by can be solved This problem after the Big Bang. Before this period of inflation, the entire Univer entire the inflation, of this period Before Bang. theafter Big were today regions separated Widely temperature. a common to and equilibrate ( have regions these from photons why explaining Universe, early the in together temperature. same inflati the consider to is Universe the of expansion the for model simple A expa the of centre the be atto themselves consider might balloon on the point any the Universe inflation, During away. further are getting points neighbouring e about • • PoS(ICRC2015)511 erse. If there If erse. inty in the initial in initial the inty nary matter through through matter nary the Universe falls short short falls Universe the e recession velocity of velocity e recession ventually to recollapse in to recollapse ventually laxies. laxies. n the Universe. Gravity will cause cause will Gravity the Universe. n change as the Universe expands. expands. Universe the as change omogeneous - each point spatial - omogeneous s gravitational attraction is strong strong is attraction s gravitational o slow down. If the density of the of the density If down. slow o riously balanced between these two these between balanced riously ationary period, when fluctuations are are fluctuations when period, ationary ertain point the expansion proceeds proceeds expansion the point ertain

uantum fluctuations in very the early Universe How Much Matter Does The Universe Contain? Contain? Universe The Does Matter Much How . Inflation asworks a cosmic microscope to see the q is Universe h inflationary the of evolution the physics, classical Using evolves exactly the same way. However, quantum physics introduces some uncerta some introduces physics quantum However, way. same the exactly evolves points. spatial different thefor conditions infl the After formation. structure for seeds as act These variations i place to place from slightly vary will of matter density the amplified, ga of to formation the leading contracting, to start regions dense the more An important question today in cosmology is how much mass is contained in the Univ in the contained is mass is much how in cosmology today question important An were no matter filling the Universe, the Universe would expand forever and th and forever expand would Universe the the Universe, filling were no matter not would Universe the of expansion the to respect rest with at objects ordi and matter, but with filled empty not is Universe the that of course, We know, t Universe the of expansion the causing matter, attracts other gravity thi density, critical the as known threshold certain a exceeds Universe e it causing Universe, the of expansion the reverse and later to stop enough of density average the if hand, other the On Crunch." "Big the as known what is a c after and forever, expands Universe the density, critical of the preca lies critical A Universe empty. were asthe if Universe much possibilities. • • PoS(ICRC2015)511 )

total called an called . ght then become a become then ght niverrse niverrse According to the According nergy term and the term nergy st this time, these universes universes these time, this st iverse expands. If (1 − If expands. iverse m and the trailing curvature curvature trailing and the m ation, or ultralight, a finite finite a or ultralight, ation, < −1/3 and will dominate the dominate and will < −1/3 ω the expansion. expansion. the

. These have have . These -2 > 1, and eventually the expansion rate ˙a will go to zero. At zero. to ˙a go will rate the expansion > 1, and eventually

total

. In these universes it does not matter what total and the curvature is at is curvature the and total what matter does not it universes these . In −2 . Qualitatively this universe will evolve as a = 1 universe with no with universe a = 1 as evolve will this universe . Qualitatively −2 ) < 0, then total < 1, and the universe will expand forever and end in a Big Freeze. This case is This case Freeze. in a Big end and forever expand will universe < 1, and the = 1 universe described earlier, ending either in a Big Rip or a Big Freeze a Big Rip or a Big in either ending earlier, described universe = 1 total Big Rip, Big Freeze, Or Big Crunch : Possible End States Of U The States Possible End : Big Crunch Or Freeze, Big Big Rip,

curvature term, which goes as a which goes term, curvature any time – the universe will always expand and qualitatively qualitatively and expand always will – the universe time any asact the Friedmann equation of energy, the future of the expansion speed of the universe mi the universe of speed expansion the of the future energy, of equation Friedmann for this energy of evolution the that describes term the between competition of acceleration the of the magnitude affect not will Curvature term. a than slower dilute that forms energy at look first Let’s • • Measurements of the cosmic microwave background radiation radiation background microwave cosmic the of Measurements

For a universe dominated by cosmic strings, there is a tie between the e the between tie a there is strings, cosmic by dominated a universe For a as – both go term curvature curvature, ending in a Big Freeze. For a universe dominated by matter, radi matter, by dominated a universe For Freeze. a Big in ending curvature, un as the terms these of any to dominate grow eventually will term curvature > 0, then > 0, then “open universe.” If (1− If “open universe.” that time a maximum expansion scale factor of the universe can be found. Pa be found. can the universe of factor scale expansion a maximum time that PoS(ICRC2015)511 roughly 70% of the the 70% of roughly of physical scope, scope, physical of ng and powerful source of source and powerful ng time when the relevant relevant the when time = −1 energy will evolve as evolve will energy = −1 osmological parameters parameters osmological ng was an interesting enough enough an interesting was ng ω iverse that spends a significant a significant spends that iverse to unity. Alternatively, a Alternatively, to unity. ies on the cosmological model can can model the cosmological on ies realized, the standard model of of model standard the realized, ferences in the anisotropies. The anisotropies. the in ferences total that the the that Physics 1971-1980, EditorLundqvist, Stig > −1/3 phase drives total away from unity. unity. from away total drives phase > −1/3 of the universe will continue to approach approach to continue will the universe of ω ω . If so, the ultimate future of the universe is unknown. is unknown. universe the of future the ultimate so, . If ω , Penguin Editions, 3018. Nobel Lectures , in , in = −1, and if the energy forms in the universe today are stable, stable, are today universe in the forms energy the if −1, and =

ω < −1/3 energy phase drives drives phase energy −1/3 < 01

ω , A briefer History of Time The Origin Of Elements Parallel Worlds Finale : Testing Inflationary Cosmology Cosmology Inflationary : Testing Finale World Publishing Scientific Co., Singapore, 1992. • • Stephen • Hawking, Arnold Penzias, • • Michio Kaku,

universe that spends a significant time being dominated by a by dominated being time a significant spends that universe will collapse into a Big Crunch. It is also useful to understand that any un any that to understand is useful also It Crunch. a Big into collapse will amount of time being dominated by a by dominated being of time amount If present observations continue to support the concordance cosmology where cosmology concordance the to support continue observations present If where a form inis universe in the energy then the universe should continue to expand and the average average the and expand to continue should thethen universe −1. The fate of the universe will then be a Big Freeze. It is possible possible is It Freeze. a Big be then will universe the fateThe of −1. a field and/or decay into energy forms with higher forms energy into decay and/or a field • suppose, than we queerer is only not “The universe suppose.” can we than is queerer It Haldane. -J.B.S. interesti remarkably is a radiation background microwave cosmic The an early at of the universe image provides an It cosmology. about information anisotrop of dependence so the simple, very all were processes physical decoupli at universe the time, same the At precision. high with be calculated dif measurable will produce in cosmology differences small that place c fundamental to determine potential the ultimate has background microwave is this promise If precision. percent-level with the universe describing terms in particle physics of model standard the with would compare cosmology of confirmation. and detail power, explanatory References