1The Early UniverseChapter 12 – Hawley/Holcomb“Unity in the Whole Structure”• “…How is it possible by any methods of observation yet known to the astronomer to learn anything about the universe as a whole? It is possible only because the universe, vast though it is, shows certain characteristics of a unified and bounded whole. …science shows unity in the whole structure, and diversity only in details.”» Simon Newcomb, 1906What I’m Going to Talk About• The Big Bang Theory of the Formation of the Universe– Radiation, Matter and the Physical Laws• Kirchoff’s Spectroscopic Laws Bohr’s Atom• Planck’s Radiation Curves Wien’s Law• Stefan-Boltzmann Law Kepler’s Laws of Planetary Motion• Newton’s Law of Motion Newton’s Law of Universal Gravitation• Maxwell’s Equations for Electromagnetism Doppler Effect• Hubble’s Law Einstein’s Special Theory of Relativity• Einstein’s General Theory of Relativity Gamow’s Big Bang• The Beginning?• The Cosmological Timescale– Eras and Epochs• Spacetime Inflation• The Formation of Galaxies• EvidenceSome Basic Physics• Kirchoff’s Spectral Laws– Continuous Spectrum• any body (ideal blackbody) that is at a temperature above 0 K– Emission Spectrum• any low pressure gas that you place a high voltage across– Absorption Spectrum• any low pressure gas placed between a blackbody and the observerBohr’s Atom• Best described the workings of the Hydrogen atom– one proton and one electron “around” the proton moving in orbits that are discretized (quantized) so that no intermediate orbits are allowedAbsorption EmissionPlanck’s Radiation Curves• A way to depict frequency (inverse of wavelength) versus intensityFrequencyIntensity2Wien’s Law• Peak wavelength is inversely proportional to the temperature of the blackbodyIntensityFrequencyCooler BodyHotter BodyPeak WavelengthStefan-Boltzmann Law• Energy radiated by blackbody is proportional to the temperature to the 4th powerE = σ T4Energy vs. Temperat ure01000020000300004000050000600000246810121416TemperatureEnergyKepler’s Laws• Kepler’s First Law of Planetary Motion– planets orbit sun in an ellipse with sun at one focus• Kepler’s Second Law of Planetary Motion– planets sweep out equal areas in equal times• travel faster when closer, slower when farther• Kepler’s Third Law of Planetary Motion– orbital period squared is proportional to semi-major axis cubedP2= a3Newton’s Laws I• Newton’s First Law of Motion– body at rest tends to stay at rest and body in uniform motion will stay in straight line uniform motion unless acted upon by an outside force• Newton’s Second Law of Motion– the acceleration of a body is proportional to the force being appliedF = m aNewton’s Laws II• Newton’s Third Law of Motion– for every force there is an equal and opposite force (action and reaction)• Newton’s Law of Gravitational Attraction– force is proportional to masses and inversely proportional to the distance squaredF = (G m M) / r2Doppler Shift• A change in measured frequency caused by the motion of the observer or the source– classical example of pitch of train coming towards you and moving away3Maxwell’s Electromagnetism• Electricity according to Gauss– relates electricity to electric charge• Faraday’s Law– relates electric fields to magnetic fields• Magnetism according to Gauss– relates magnetism to electricity• Ampere-Maxwell Law– relates magnetic field to electricityEinstein’s Relativity Theories• Special Theory of Relativity– speed of light constant in all reference frames• time dilation and simultaneity• length and mass• addition of velocities• General Theory of Relativity– Principle of Equivalence– curvature of space-timeHubble’s Law• The further away a galaxy is, the greater its recessional velocity and the greater its spectral red shiftv = H0dThe value of the Hubble constant, H0, is not known with certainty but best value today is approximately 71 km/s/MpcThere is a linear relationship between the distance a galaxy is from the Earth, and, the redshift of that galaxy (which is a measure of the speed with which a galaxy is moving away from the Earth)Hubble’s Conculsion• From Hubble’s Law we can calculate a time in the past when universe was a point• Big bang occurred about 13-15 billion years ago– big bang formally proposed by Gamow based upon such evidence• Big bang theory progenitors existed in looser manner4Gamow’s Big Bang and Hoyle’s Steady State• Steady State Universe– universe looks same and will look same• continuous creation• Big Bang Universe– universe began in “big bang” or “ylem”• single point of creation“In The Beginning”• “In the beginning, God created the particles and the antiparticles. Now the temperature was high, and the particles and the antiparticles were in equilibrium…And God said, ‘Let there be light’…and He separated the photons from the particles and antiparticles. God called the photons “bosons” and the particles and antiparticles He called “fermions.” And there was pair production and there was photon creation -- the first 10-43seconds.”» Eric Schulmanfrom “A Briefer History of Time”Details of the Big Bang• The littlest of physics• The Big Bang & ensuing Cosmic Eras– The Vacuum Era• The Planck Epoch and The Inflationary Epoch– The Radiation Era• Light and Baryons• The Electroweak Epoch and The Strong Epoch• Decoupling and the creation of matter– The Matter Era• Transition to matter• Galaxy Formation Epoch and Stellar Epoch– The Degenerate Dark Era• Dead Star Epoch and Black Hole Epoch– Whither the future?The Littlest of Physics• Space, Time, Matter and Forces• Types of Matter– Quarks -> Baryons• protons, neutrons– Electrons -> Leptons• electrons, neutrinos, muons• Types of Forces– gravity, electromagnetism, strong, weakBack to the Beginning• The universe began as an infinitely dense cosmic singularity which began its expansion in the event called the Big Bang, which can be described as the beginning of time• During the first 10–43second after the Big Bang, the universe was too dense to be described by the known laws of physicsThe Vacuum Era• The Planck Epoch–<10-43sec. and about 1019GeV (1 GeV = ~1013K)– we just don’t know• The Inflationary Epoch–>10-43sec., < 10-10 sec.–