The Beginning of the Universe 8/11/09 Astronomy 101
Astronomy Picture of the Day Astronomy 101
Outline for Today Astronomy Picture of the Day Return Lab 11 Astro News Q&A Session Dark Energy Cosmic Microwave Background Radiation The Early Universe -- Inflation The Early Universe Nucleosynthesis The End of the Universe Minute Writing Break Astronomy 101 Lab 13 -- Nucleosynthesis
Questions for Today What does Dark Energy mean for the past and future of the Universe? How can we observe the Big Bang? Why does the Universe look the same everywhere? How did matter and elements form? What will happen eventually? Astronomy 101
Astronomy 101
The Problem... There are globular clusters older than the calculated age of the Universe Astronomy 101
Type of universe determines distances to galaxies at a given redshift The point where any of the models intersects the pink line occurs at the same redshift Open universe Longer distance Dimmer! Closed universe Shorter distance Brighter! Astronomy 101
Use Supernovas to Figure Out What Distance Equals What Redshift-> Find How H has Changed Astronomy 101
Astronomy 101
Astronomy 101
If H is measured to be larger at great distances, then the A) Universe must be older than we suspect B) Matter in the Universe is not important to its motion C) Expansion is slowing D) All of the above Astronomy 101
If H is measured to be larger at great distances, then the A) Universe must be older than we suspect B) Matter in the Universe is not important to its motion C) Expansion is slowing D) All of the above Astronomy 101
The Edge of the Observable Universe How far away can we see? What do we see and what is its redshift? Astronomy 101
At a redshift of z 1300 Universe was very smooth! Sea of very hot, ionized gas and energetic photons. Photons are continually scattering off of free electrons. Universe is opage Has thermal spectrum Similar to the interior of the Sun 14
As the Universe expands, the photons all redshift to lower Starts here energies But at slightly lower redshifts the photons wind up here Like the atmosphere of cool stars, the gas can no longer stay ionized; Univers is transparect 15
These photons never interact with matter again! They were emitted at redshift ~ 1300, with a thermal spectrum of 3000K 16
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Penzias & Wilson at Bell Labs, 1965 18
The Cosmic Microwave Background (CMB) radiation. A perfect thermal spectrum at 2.7K! (3000K spectrum redshifted from z~1300) The same in every direction Density of the Universe was uniform to better than 0.01% 19
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What do the Fluctuations Mean and What Can They Tell Us Size of Ripple Before Expansion = Quantum Fluctuation Size of Ripple After Expansion = Very Big! 25
Mass (Desity) Curves Space Low Density Critical Density High Density 26
Geometry in flat spaces: But matter curves space -Can we measure that curvature? 27
Geometry in curved spaces: Positive Curvature 28
Geometry in curved spaces: Negatively Curved 29
Fluctuation s size (Mpc) fixed by theory Flat _ + Apparent angular size reveals which geometry is right for our universe! 30
Close to Black Hole, How Would You Expect Space to Be Curved? A) Positively Curved (globe) B) Flat C) Negatively Curved (pringels) 31
The bumps in the CMB say that the Universe is flat (density = critical)! Real Data Prediction for closed, flat, and open universes! 32
Why is the Universe Flat? Dark Matter and Baryonic Matter aren't enough to make the Universe flat Dark Energy (remember E = mc2) provides extra mass 33
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Why is the Universe Flat? Dark Matter and Baryonic Matter aren't enough to make the Universe flat Dark Energy (remember E = mc2) provides extra mass Still why is it so flat? 35
Furthermore Why is it so Flat? Smooth? Big? 36
Furthermore Why is it so Flat? Smooth? Big? Inflation 37
Inflation 10-36 seconds after the Big Bang, for 10-34 seconds, the universe expanded in size by >1043 times! Increasing time Scale of Universe 38
Inflation makes the Universe flat! 39
Inflation makes the Universe Smooth Opposite sides of the Universe are exactly the same temperature (within 0.00003K)! 40
Inflation makes the Universe Smooth 41
Inflation makes the Universe Big 42
What would H have been during Inflation? A) Much Higher B) Somewhat Higher C) The Same as Now D) Much lower 43
What would H have been during Inflation? A) Much Higher B) Somewhat Higher C) The Same as Now D) Much lower 44
Then What Happens? Inflation ends after ~10-34 seconds (or so). Universe goes back to a normal pokey rate of expansion. Temperature and energies are incredibly high! Weird physics takes over, but gradually shuts down as the Universe expands and cools. 45
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Forces Unite at High Temperatures Four known forces in universe: Strong Force Electromagnetism Weak Force Gravity Yes! (Electroweak) Maybe (GUT) Who knows? (String Theory) Astronomy 101
GUT Era Lasts from Planck time (~10-43 sec) to end of GUT force (~10-38 sec) Astronomy 101
Electroweak Era Lasts from end of GUT force (~10-38 sec) to end of electroweak force (~10-10 sec) Astronomy 101
E = mc2 Astronomy 101
Particle Era Amounts of matter and antimatter nearly equal (Roughly 1 extra proton for every 109 protonantiproton pairs!) Astronomy 101
Era of Nucleosynthesis After antimatter is annihilated ~ 0.001 sec Nuclei begin to fuse Proton to Neutron Ratio Set Astronomy 101
Era of Nuclei Helium nuclei form at age ~ 3 minutes Universe has become too cool to blast helium apart Astronomy 101
Era of Atoms Atoms form at age ~ 380,000 years Background radiation released Astronomy 101
Era of Galaxies Galaxies form at age ~ 1 billion years Astronomy 101
If the Universe had cooled down faster, there would be A) Less Helium B) The same amount of Helium C) More Helium Astronomy 101
What will the future be like? 58
Minute Writing What are the main points of this lecture? Astronomy 101
Assignments Read Chapter 24 Read Lab 14 NO News Article due next Tuesday Lab 12 due Thursday Final Exam is a week from today Astronomy 101