Discovery of the Expanding Universe: Ptolemy to Big Bang - Prof. Kenneth E. Lulay, Papers of Materials science

Download Discovery of the Expanding Universe: Ptolemy to Big Bang - Prof. Kenneth E. Lulay and more Papers Materials science in PDF only on Docsity! In the Beginning… WOW! Detailed Overview for Today’s Talk • Short political statement • Some history mixed with some really cool pictures! • Really cool pictures mixed with some information What is this? Have you seen it? What is this? Have you seen it? Star Parties: a bunch of geeks staying up all night to look at the sky Visit Rose City Astronomer’s web page Stepping back a few years… Ptolemy (83-168AD): Greek philosopher, earth centered universe 1 \ 2, Venus Mars.» AJAT1996 1543, Nicolaus Copernicus moved the earth: the sun become the center of the universe. Kepler’s Laws • 1604 Kepler observed a temporary “new star” – The heavens were not immutable!? • 1605 Kepler determined the motion of planets around the sun 1610, Galileo provided evidence to support Copernicus … …oops Skipping ahead a few years… 1910’s • The Milky Way was the Universe • All fuzzy objects (nebula) were thought to be within the Milky Way. • The universe was “static” – not changing • Universe was eternal! • Einstein believed in a static, eternal universe – modified relativity to match that. Moon is superimposed, but the scale is correct in regards to apparent size. Andromeda: galaxy or nebulae? Andromeda is Big. Andromeda is the furthest “naked eye” object Galaxies are Far Far Away! • Cepheid variable stars: brightness increases and decreases periodically. • True brightness is a function of brightening cycle period • Used as “standard candles” – Determine true brightness – Measure apparent brightness – Calculate distance 100 Inch Hooker Telescope Mt. Wilson Observatory Construction of mirror: 1917-1948 Some nebula are extra- galactic: The Universe got a LOT BIGGER! NGC 6822 in Sagittarius Big but Semi-Static • The Universe became BIG with Hubble’s discovery • But it was still considered to be static – Maybe things move, but don’t really change • Eternal! – Possibly, new matter is created to fill in voids – Possibly, red shift is “tired light” • Or maybe… • Lemaitre…the “new Galileo”? • Considered “running the expansion clock backwards” which… • …challenged the norm of an eternal, static universe. • Replaced it with a universe that had a beginning. Fr. Georges Lemaitre 1927 paper: A homogeneous universe of constant mass and growing radius accounting for the radial velocity of extragalactic nebulae Ralph Alpher and Robert Herman • Run the “expanding universe” clock backwards • The universe compresses and gets very very very hot! • These conditions are replicated in particle accelerators. • 0.01 seconds after the “beginning” the universe was about 1010K (a.k.a. hot). • Neutrons, protons and electrons formed from quarks • 7 protons for every 1 neutron Race Against Time • For the next few minutes fusion combined protons and neutrons into atomic nuclei • After a few minutes, expansion cooled the universe such that no more fusion could occur. All matter was done forming! • Created 75% H and 25% He Bethe – every thing else? • Hans Bethe et al., showed elements such as oxygen, carbon and nitrogen are created inside stars. • What about other elements? (stay tuned) Two Successes! • By late 1950’s the “Big Bang” theory was supported by two significant observations: – Red shift shows the universe is expanding – Actual observed He/H ratio is what it should be if the “big bang” is real • Still, many physicists not convinced… Interesting coincedence • Three of the physisists involved with nuclear fusion were: • Ralph Alpher • Hans Bethe • George Gamow Penetrates Earth's : N N Atmosphere? Radiation Type Radio Microwa Infrared Visible Ultraviolet Gamma ray Wavelength [11 ig? io® ia§ os xio% ir? 10 wr me a Approximate Scala ae ot Wavelength At vi diy Buildings = Humans Bu ams Ataraic Nucla Frequency (Hz) 1 Temperature ot abjects at which ¢ this radiation is. the f | most intanse ° l | | 1K 1000 K 10,000 K 19,000,000 K wavelength emutted ayare wae g 727°C ~ 16,000,080 °C Persistence Pays Off… • 1964, Arno Penzias and Robert Wilson • Microwave work with Bell Labs • Observed “hiss” in their detector that they could not explain • Since it was isotropic – it seemed to be noise. • They persisted… oP] oD) OQ. © YO N oD) — oD) - Their One last problem: isotropy The temperature appeared to be perfectly uniform How could stars and galaxies form if mass was perfectly distributed? Wilkinson Microwave Anisotropy Probe (WMAP) Problem solved: Almost perfectly uniform…but not quite… High resolution cosmic background radiation image from WMAP (Wilkinson Microwave Anisotropic Probe) Temperature variations (∆Temp ~ 0.005°C) indicates “clumping” of matter which resulted in galaxy formation Big Bang Theory • Not an explosion in the universe • Universe itself started at a “singularity” – not static – expands “into itself” • Very firmly established theory (mid 20th) – only existing theory that explains the data • red shift, H/He ratio, Cosmic background radiation • Still being modified (ex. inflation) Big Bang - Events • Prior to 10-6seconds, no matter, only energy • 10-6 seconds - quarks formed • By 1 second - all matter created – Tuniverse=1010 K – 7 protons for every 1 neutron – This results in 75% H and 25% He The big bang — 10" second Formation 1-36 second Probable ere of pani from quires second 3 minutes 10- second tor! ‘Quantum gravily era nagnetic.are and gravitationa formes 300,000 yours First atoms fonm 100 million years First slar and qua 10 to 15 billion years. Modem galaxies appear There is more to life than hydrogen and helium! Thank your lucky stars! Elements lighter than iron are created inside stars by fusion. But how did it get here? Stellar Evolution • Stars convert H in to He at their core • When hydrogen is depleted – gravity overcomes thermal forces • core shrinks rapidly – outer shell expands 50X – Red Giant with helium core – Helium starts to “burn” (nuclear fusion) Planetary Nebula (Cat’s Eye Nebula - 3000 Light years away) Light elements: C, N, O Outer shell of star is cast out in to the universe. Star still burns at the center. Star will become a white dwarf. Cats Eye Nebula Stellar Death • Death of a very large star (> 8 solar mass): – fusion in the core ends (no more fuel) – no more thermal energy to prevent collapse – collapse occurs in 1/10 of a second! – Super Nova Explosion • For weeks the star is 109 brighter than the sun • Releases its heavy elements • Explosion energy fuses the heaviest elements Crab Nebula (Super Nova Remnant) Super Nova of 1054 AD, visible in daylight for 23 days, 6000 light years distant, now 10 light years across X-ray (Chandra) Infrared (Spitzer) Crab Nebula (Combined Images including optical wave lengths) * * or . CJ ” ° ¥ J ns cine ei Elec aig cee Cd a o ae « . - J pant eects eam Plea er aes 3 . > | - . * od a Palle) sah 2006 jz 2006kd PTs) PUG es) A eis lil 7 , os “ . ? - . Fotis ee as EAE eg ‘ eae oay EL PLT EL oet ere Supernova in many galaxies Supernova to be: Eta (η) Carinae GRB 080319B Gamma Ray Bursts: *brightest objects in universe *Thought to be collapsing stars (>30solar mass) March 19, 2008 – above GRB was a naked eye object But is over 7 Billion light years distant! 100 times brighter than all stars in Milky Way combined! Okay, stuff gets “blown out” Then what? Dust (C, Fe, etc.) Pillars of Creation In the Eagle Nebula Orion Nebula Pleiades (very tiny dipper) Star Clusters Double Star TlustenNGC+1 ee