112evidence, on-going experiments, fate3Learning Goals for this LectureLearning Goals for this Lecture• Describe the empirical data (the observations) that led to theassumption that there was a “Big Bang.”• Outline the events that led to the discovery of the cosmicmicrowave background radiation.• Explain why it is that we will never be able to use “look-backtime” to witness the Big Bang.• Summarize the main points in the current theory of the birth ofthe Universe and the supporting observational evidence:– Inflationary period– Particle era• Explain what experiments the Large Hadron Collider isconducting that will simulate the conditions at the Big Bang.24The Universe is Expanding -The Universe is Expanding -! v = Hod5Discovery of cosmic microwave background radiationDiscovery of cosmic microwave background radiationhttp://www.youtube.com/watch?v=SB_Qfngi0mo26:15 - 31:156Consensus for this modelbrought about by the presenceof empirical empirical datadata• Recession of distant galaxies• Evolution of galaxies - lookback time• Weak radio static that fillsthe Universe: Heat of the birth• A dark night skyObservational FoundationsObservational Foundations37OlberOlber’’s Paradox: s Paradox: Why isn't the night sky uniformly bright?Why do we expect the night sky to appear uniformly bright in a Steady State Universe? This theory is based on three assumptions: Universe is 1. Uniform (will observe no differences among galaxies) 2. not expanding (will observe no redshifts) 3. of infinite proportions (in both time and space)In ALL directions, our eyes would fall upon astar. If not a star, then a galaxy.Solution: Universe had a beginning. Lightfrom distant galaxies hasn’t reached us yet.Stars die.Wikipedia8The CMBR is a curtain that prevents our seeing fartherThe CMBR is a curtain that prevents our seeing farther(Explain why it is that we will never be able to use “look-back time” to witness the Big Bang.)9Learning Goals for this LectureLearning Goals for this Lecture• Describe the empirical data (the observations) that led to the assumption that there was a “BigBang.”• Outline the events that led to the discovery of the cosmic microwave background radiation.• Explain why it is that we will never be able to use “look-back time” to witness the Big Bang.• Summarize the main points in the current theory of the birth ofthe Universe and the supporting observational evidence:– Inflationary period– Particle era• Explain what experiments the Large Hadron Collider is conducting that will simulate theconditions at the Big Bang.410Big Bang was not centered in any one place – it occurred everywherebecause there was nowhere else!All of space AND time was created in that instantAll of space AND time was created in that instant11Our visible UniverseInflationary theory explains 3 main sticky points:Inflationary theory explains 3 main sticky points:1) Where does structure come from?2) Why is the overall distribution ofmatter so uniform?3) Why is the density of the universeso close to the critical density?12Inflationary Period ExplainsInflationary Period Explains1) Where does structure come from?2) Why is the overall distribution of matter so uniform?3) Why is the density of the universe so close to the criticaldensity?513Review of the first 3 minutesReview of the first 3 minutes14Chapter S4 of textpp. 449 - 465Fermilab15Large Hadron ColliderLarge Hadron ColliderHadrons are made of quarksheld together by the strongforce (gluons)--baryons (made of threequarks; e.g. protons, neutrons)--mesons (made of one quarkand one antiquark; chargedmesons decay to electrons andneutrinos. Uncharged mesonsmay decay to photons.)616Fundamental building blocksof atoms: up quark, downquark, and electronmatter and antimatter are real! m =Ec2" E = mc217•Decoupling of light and matter•Atomic Era•Ratio H : He set•Nucleosynthesis•Quarks combined•Particle Era22mcEcEm =!=18Learning goals:Learning goals:• What are the analogies between the regions of theSun and the events of the early universe?• List the theoretical foundations for cosmology.• What do the data from observations using the WMAPsatellite imply about the “shape” of the Universe?719Analogies with interior of SunAnalogies with interior of Sun20After the first 3 minutes:After the first 3 minutes:21 General Relativity: Space and Time are one Cosmological Principle: When averaged over extremely largeregions, the Universe is homogeneous AND isotropic There is no special place.Homogeneous:looks the same toall observersIsotropic: looks thesame in all directionsHomogeneousand IsotropicTheoretical foundations for cosmologyTheoretical foundations for cosmology822There is no special locationThere is no special location;; the Universe is infinite; or, if not the Universe is infinite; or, if notinfinite, then infinite, then humongouslyhumongously large. large. The speed of light is finite; itThe speed of light is finite; ittakes time for different parts of the Universe to communicate.takes time for different parts of the Universe to communicate.There hasnThere hasn’’t been enough time to see parts of the Universe that aret been enough time to see parts of the Universe that aredifferent!different!This logic can go on and on and on and on …….We can’t have a galaxy at the edge of the “nothingness” becausethat would be a special place!232.7249 K 2.7251 KWilkinson Microwave Anisotrophy Probe24Supports predictions of Big Bang theory -- is consistent. If thiswere not the case, the MAP observations could have spelleddoom for the Big Bang theory for the origin of the Universe.http://wmap.gsfc.nasa.gov/http://wmap.gsfc.nasa.gov/resources/camb_tool/index.html925Is there enough mass to halt expansion of the Universe?WMAP RESULTS26Five ages of the UniverseFive ages of the Universe• Primordial era - Big Bang through formation ofstructure• Steiferous era - Now: Gravity wins some battles• Galaxies form• Structure and superstructure appears• Planets form around stars• Degenerate era - white dwarfs, neutron stars, browndwarfs; galaxies disappear• Black hole era - even black holes will eventuallyevaporate• Dark era27After 100 cosmological decades, nothing is left exceptwaste products of astrophysical processes: photons ofcolossal wavelength, neutrinos, electrons, and positrons.Perhaps weakly interacting dark matter particles and otherexotica are present as well.The
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