THE BIG BANGSlide 2New York Times: April, 2003Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Physical Law and the UniverseEINSTEINEinstein + CopernicusSlide 13HUBBLE (1921)The Cosmic Microwave BackgroundArtist’s Rendering of COBESlide 173 minutes: Synthesis of the Light ElementsResults of Detailed Nucleosynthesis Calculations:Slide 20The CMBR and the Copernican PrincipleMAP OF THE SKYIs this reasonable?So it’s not reasonable!Yes!Observational ConfirmationWMAP ORBITDetailed information about the universe:COMPOSITION OF THE UNIVERSEA Confusing Picture: Where Do We Stand?What’s the Problem?What do we know?PDG Wall ChartOne possible new phenomenon: SupersymmetrySlide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41THE BIG BANGHOW CLOSECAN WE COME?Michael DineMay, 2003New York Times: April, 2003Reports a debate among cosmologists about the Big Bang.lll1.htmlDr. Tyson, who introduced himself as the Frederick P. Rosedirector of the Hayden Planetarium, had invited five"distinguished" cosmologists into his lair for a roastingdisguised as a debate about the Big Bang. It was part ofseries in honor of the late and prolific author IsaacAsimov (540 books written or edited). What turned out to beat issue was less the Big Bang than cosmologists'pretensions that they now know something about theuniverse, a subject about which "the public feels somesense of ownership," Dr. Tyson said. "Imagine you're in a living room," he told the audience."You're eavesdropping on scientists as they argue aboutthings for which there is very little data."Dr. James Peebles, recently retired from Princeton, whom he called"the godfather"; Dr. Alan Guth from the MassachusettsInstitute of Technology, author of the leading theory ofthe Big Bang, known as inflation, which posits a spurt of akind of anti-gravity at the beginning of time; and Dr. PaulSteinhardt, also of Princeton, who has recently beenpushing an alternative genesis involving collidinguniverses. Rounding out the field were Dr. Lee Smolin, a gravitationaltheorist at the Perimeter Institute for Theoretical Physicsin Waterloo, Ontario, whom Dr. Tyson described as "alwaysgood for an idea completely out of left field - he's hereto stir the pot"; and Dr. David Spergel, a Princetonastrophysicist.But Dr. Smolin said the 20th-century revolution was notcomplete. His work involves trying to reconcile Einstein'sgeneral relativity, which explains gravity as the"curvature" of space-time, with quantum mechanics, thestrange laws that describe the behavior of atoms. "Quantum mechanics and gravity don't talk to each other,"he said, and until they do in a theory of so-called quantumgravity, science lacks a fundamental theory of the world.The modern analog of Newton's Principia, which codified theprevious view of physics in 1687, "is still ahead of us,not behind us," he said. Although he is not a cosmologist, it was fitting for him tobe there, he said, because "all the problems those guysdon't solve wind up with us."Today, you are listening to someone seemingly more out in left field-- a particle physicist.Particle physics: seeks to determine the laws of nature at a ``microscopic” – really submicroscopic, level.What does this have to do with the Big Bang? EVERYTHING!With due respect to the New York Times, articles like this give a very misleading impression.We know:•There was a Big Bang•This even occurred about 13 Billion Years Ago•We can describe the history of the universe, starting at t=3minutes•There is now a huge amount of data and a picture with great detail.There are lots of things we don’t know. With due respect to Lee Smolin, the correct address for these questions is Particle Physics. We can’t answer any of these questions without resolving mysteries of particle physics. These will be the subject of this talk.•What is the dark matter?•Why does the universe contain matter at all?•What is the dark energy?•What is responsible for ``inflation”?•What happened at t=0?Physical Law and the Universe•Newton: F=ma FG= M1M1/R2 Motion of Planets• Laws of electricity and magnetism, nuclear physics: Understanding of Stars•Einstein: General Relativity – Expansion of the UniverseEINSTEIN•1905: special relativity, photoelectric effect, Brownian Motion•1916: General Relativity •Culmination of a 9 year struggle to understand Newton’s Gravity, starting with ``equivalence principle”• Tests: Precession of Mercury’s Orbit, Bending of LightImplications for the universe: COSMOLOGYEinstein + CopernicusAssume the universe is homogeneous and isotropic – no special place or direction.Einstein’s equations have no Static solutions.The universe expands!Einstein was very troubled – remember that at that time (c. 1920)Astronomers didn’t know about galaxies!Edwin Hubble, who started out as a lazy, rich kid, became one of the most important of all astronomers.HUBBLE (1921)Galaxies move away from us at a speed proportional to their distanceThe Cosmic Microwave BackgroundStill, limited evidence for aBig Bang. Gamow, Peebles: if true, there should be a ``glow” left over from thisHuge explosion (but of microwave radiation, not light). Objects give off a characteristic spectrum of electromagnetic radiation depending on their temperature; ``blackbody.”The temperature then was 20,000 degrees; today it would beAbout 6 degrees Discovered by Penzias and Wilson (1969).Today: thanks to COBE satellite, best measured black body spectrum in nature.Artist’s Rendering of COBECOBE measured the temperature of the universe:3 minutes: Synthesis of the Light Elements•CMBR: A fossil from t=100,000 years.•He,Li,De: Produced at t=3 minutes pn e+Neutrino reactions stop; neutrons decay.Results of Detailed Nucleosynthesis Calculations:•The fraction of the universe made of ``baryons”=protons + neutrons:•During last two years, an independent measurement from studies of CMBR:Very impressive agreement!The CMBR and the Copernican PrincipleJust how homogeneous and isotropic is the universe? Reasonably so for galaxies on scales of 100’s of millions of light years.What about the CMBR? -- the temperature is the same to a part in 10,000 in every direction in the sky!Small variations only observed in 1993. Now studied with great precision.MAP OF THE SKYIs this reasonable?Remember, the CMBR is light from the time that the universe was 100,000 years old. At that time, 1,000 times smaller