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Big Bang, Black Holes, No Math ASTR/PHYS 109 Dr. David Toback Lecture 19 Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 1 Was due Today – L19 • • • • • Reading: – (Unit 4) Pre-Lecture Reading Questions – Unit 1: If you received a ContactInstructorAgain, send me an email – Unit 3: Let us know if you were misgraded – Unit 4, Stage 1: Was due before class Today End-of-Chapter Quizzes: – Chapter 12, parts a&b Papers: – Paper 1 Revision: Let us know if you were misgraded – Paper 2 Revision (if desired), Stage 1: due Monday before Class – Paper 3, Stage 1: due next Wednesday before class • If you want feedback on a draft, submit before Sunday at 11:55PM Honor’s Paper: – Stage 1: Must be approved explicitly – Stage 2: Due Monday Nov 14th – Final paper due on the last day of class Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 2 Unit 4: Evolution of the Universe • Big Picture of the Evolution of the Universe: Temperature and Time • Collisions and how they explain what we see • The First Three Minutes • After the First Three Minutes Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 3 Getting Started We now have a basic understanding of the evidence for the Big Bang Lets look at the Evolution of the Universe after the Big Bang Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 4 The Big Bang •Ideally we’d start telling the story at the Big Bang itself and then move forward •Maybe even talk about what came BEFORE the Big Bang •Unfortunately, we don’t REALLY understand the Bang part or if there even was a bang Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 5 Best We Can Do • The best we can do with confidence is start describing the Universe a short time AFTER its beginning • Start there, then work our way forward and backward in time What happened RIGHT AFTER the Big Bang? Then what happened after that? Then what? Etc. Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 6 The Big Bang Theory • A Big Bang occurs and the early Universe has the same temperature with lots of high energy particles • Then the Universe gets – Bigger – Older and – Colder • As time goes by it changes over time – Often we use the word evolves Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 7 Universe cools down as time passes The History of the Universe 10 billion degrees 1 degree 1 second 10 billion years Bigger wavelengths Smaller energies The Evolution of the Universe Big Bang, Black Universe expands as time passes Smaller Temperature Topic 1: The Early Universe Holes, No Math 8 What happens at Different Times? Particles, nuclei and atoms interact in different ways at early times and later times – Early Times High Temperature High energy collisions – Later Times Low Temperature Low energy collisions The Evolution of the Universe Big Bang, Black Holes, No Math Topic 1: The Early Universe 9 Various Times Explain what happens during each of a number of different periods in time – The VERY early universe Chap 13 – The first three Minutes – The next 300,000 years Chap 14 – The next billion years – ~13 billion years later (now) } Chaps 15-17 – The ultimate fate } Unit 6 of the universe? • The first four will take a couple of lectures } } Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 10 What Happening? What happens to the particles at each of these times? Collisions! Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 11 Collisions In each collision a number of things can happen • Can create new particles » Only in high energy collisions – Particles can combine to form composite objects » Protons, neutrons, atoms etc. – Composite particles can get broken up – Collisions can transfer energy Thus, the energy of the particles and what particles CAN exist in nature has a HUGE impact on the evolution of the early universe Should also say that particles can decay Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 12 A Brief History of Time • Zero • The Big Bang (?) • Well before a trillionth of • Universe comes to have the a second same temperature everywhere • One millionth of one • Quarks and gluons combine to second form protons and neutrons • A few minutes • Protons and Neutrons combine to form deuterium and helium nuclei • A few hundred thousand • Protons and electrons combine years to form hydrogen atoms • 100 million to 1 billion • Stars and galaxies begin to years form • 9 billion years • Our solar system forms • ~13.5 billion years • You take ASTR/PHYS 109 Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 13 More detail Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 14 Confidence in this Story? • How do we know this is what happened back then? • What is the evidence for it? • Will walk through the reasons next… It’s all about the energy of the collisions… Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 15 The Evolution of the Universe Overview 1. The Early Universe 2. The First Three Minutes 3. The next 300,000 years 4. The next billion years 5. The next ~13 billion years, until today The particles have the same temperature everywhere – Once the Universe has the same temperature everywhere, it doesn’t really depend too much on what The Evolution Big Bang, Black 16 came before it of the Universe Holes, No Math Topic 1: The Early Universe Not exactly sure how it all starts… Call it a Big Bang Artists conception… Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 17 Before a Millionth of a Second Lots of free particles at VERY high energies • Quarks • Photons • Electrons • Others Back when the Universe was very small it had the same temperature everywhere… Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 18 Before a millionth of a Second Lots of free particles, all with the same temperature… Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 19 Quarks can combine in the Early Universe to make a proton, but are quickly broken apart by high energy photons in the Universe Quark qqq Proton Photon + Proton qqq Nuclear Reaction Quark Big Bang, Black Holes, No Math Proton High Energy Photon Quark The Evolution of the Universe Topic 1: The Early Universe 20 Particles in the Universe: The Bathtub analogy Before a millionth of a second very high energy collisions • Lots of free quarks to make protons • Not many protons in the Universe because they are quickly busted apart Big Bang, Black Holes, No Math Protons-in-The-EarlyUniverse Bathtub The Evolution of the Universe Topic 1: The Early Universe 21 Time passes • The Universe Expands and Cools • Our story starts at a millionth of a second after the Big Bang • Cool enough that when quarks combine to form a proton or neutron they stay together – Said differently, other particles aren’t energetic enough to bust them The Evolution of the Universe Big Bang, Black apart 22 Holes, No Math Topic 1: The Early Universe A Millionth of a Second after the Big Bang The quarks have combined to form Protons and Neutrons Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 23 The Evolving Universe Early Universe Big Bang, Black Holes, No Math The Universe changes from this to this The Evolution of the Universe Topic 1: The Early Universe Later Times 24 Protons after a Millionth of a Second After a millionth of a second • No more free quarks to make more protons • Number of protons doesn’t decrease because they aren’t getting busted apart by high energy photons – Don’t exist Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 25 Very Early Universe is Still Very Complicated • The other fundamental and composite particles also have a big impact • One example is a Muon which is (for our purposes) just a heavier version of an electron –Discuss them more in Chapter 19 The Evolution of the Universe Big Bang, Black Holes, No Math Topic 1: The Early Universe 26 Photons and Muons At very high energies photons can also turn into Muon pairs + - Muon pairs can turn into Photons + Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 27 Muons are an Important Part of the Early Universe Electron Anti-Electron Photon Muon Anti-Muon Big Bang, Black Holes, No Math Muon pairs can always produce photon pairs If the photons are energetic enough they can interact and create muon pairs (or vice versa) muons, electrons and photons all have the same temperature The Evolution of the Universe 28 Topic 1: The Early Universe Why Aren’t They Around anymore? • Most particles, except protons, electrons and photons decay REALLY quickly – Some at 10-24 sec, some 10-10 sec – Muons can live for 10-6 sec • Can study lots of different types of particles here in experiments on Earth • Need an accelerator to produce most new ones if you want to study them • The photons in Today’s Universe aren’t energetic enough to produce new ones Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 29 Muon decay Electron - Muon Neutrino Neutrino Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 30 Muons in the Universe Early Universe Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe Later Times 31 Very Early Universe is Very Complicated What particles CAN exist determine what’s going on in the Very Early Universe Problem: We don’t know if we have discovered all the fundamental particles yet! • Good reasons to believe there are new ones out that we just haven’t found yet – Need bigger accelerators and/or Other tools – More on this later also The Evolution of the Universe Big Bang, Black Holes, No Math Topic 1: The Early Universe 32 Nuclei in the Early Universe Proton Proton + Proton Deuterium Deuterium + Photon Proton + Neutron Nuclear Reaction A high energy photon can break apart the Nucleus before it can find an electron to create an Atom or find another nucleon to form a bigger nucleus Proton Big Bang, Black Holes, No Math Deuterium High Energy Photon The Evolution of the Universe Topic 1: The Early Universe 33 What’s happening at about a millionth of a second after the Bang? • Lots of protons – photons can’t break them apart any more • Not many heavy nuclei: every time one forms a photon busts it apart • Not many atoms: every time one forms a photon busts it apart • Few “fancy” particles since most would have decayed already, new ones not being produced The Evolution of the Universe Big Bang, Black 34 Holes, No Math Topic 1: The Early Universe Moving towards later times… • Universe gets bigger, older and colder • By one hundredth of a second after the Big Bang there are basically no fancy particles left and the story is simpler to tell • Protons, Neutrons, Electrons, Photons etc. The Evolution of the Universe Big Bang, Black Holes, No Math Topic 1: The Early Universe 35 Where are we? Fancy particles gone by this time Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 36 Photons and Electrons at Later Times Electron Positron Low Energy photon Electron pairs interact and annihilate but photon pairs no longer turn into particle pairs Big Bang, Black Holes, No Math No easy way to produce more positrons The Evolution of the Universe 37 Topic 1: The Early Universe Approaching the Three Minute Mark • By three minutes after the bang the Universe is cool enough for Helium nuclei to form (4He) even though it doesn’t happen too much… • Complicated to produce 4He, lots of intermediate steps that are easier to break apart Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 38 Nuclei at Lower Temperatures Proton Nuclear Reaction Deuterium At these lower energies the photon can’t often break apart the Nucleus Amount of Deuterium in the Universe rises Proton Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe Photon 39 Lecture on Chapter 13 now complete Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 40 For Next Time– L19 • Reading: – (Unit 4) • Pre-Lecture Reading Questions – Unit 1: If you received a ContactInstructorAgain, send me an email – Unit 3 Revision (if desired), Stage 1: Due before class Monday – Unit 4, Stage 2: Due before class Monday • End-of-Chapter Quizzes: – Chapter 13 (if we finished Chapter 13, else just 12a & b) • Papers: – Paper 2 Revision (if desired), Stage 1: due Monday before Class – Paper 3, Stage 1: due next Wednesday before class • If you want feedback on a draft, submit before Sunday at 11:55PM • Honor’s Paper: – Stage 1: Must be approved explicitly – Stage 2: Due Monday Nov 14th – Final paper due on the last day of class Big Bang, Black Holes, No Math The Evolution of the Universe Topic 1: The Early Universe 41