The Milky Way Schroedingers Cat and You Galaxies

The Milky Way, Schroedinger’s Cat, and You Galaxies, the Building Blocks of the Universe Raja Guha Thakurta (in collaboration with Sandra Faber) UCO/Lick Observatory University of California at Santa Cruz Thursday, September 23, 2004 Kresge Town Hall Astronomy 2 (ASTR – 002 -02) Overview of the Universe

Your Cosmic History (an astronomer’s perspective) You! molecules: Earth and Sun: Protein Sun’s ancestral stars: Basic building blocks of life Home of the C, N, O atoms from which Galaxy: Their nuclear fusion reactions these protein molecules were assimilated Large family produced these C, N, O atoms of stars You are here!

Relatives of the Milky Way 3

Where did the Milky Way Come From? The Answer Will Take Us Back to the Earliest Moments of the Universe 4

The Cosmic Web of Galaxies 5

Formation of Cosmic Structures Under the Influence of Gravity A Computer Simulation + - 6

Points to Ponder • Our bio-chemical history links us to galaxies • The Milky Way and other galaxies • Galaxies like to live near one another • The formation of galaxies: The growth of primordial density fluctuations under the influence of gravity 7

But Where Did the “Seeds” of Cosmic Structure Come From? 8

Number Energy of of radiactive kernels density popping decays of the per Universe perminute 0. 9995 0. 5 1. 0000 1. 0 0. 995 1. 000 00 0. 99995 20 1. 00000 40 Quantum Noise 0 10 20 Time Position in Space 30 9

Schroedinger’s Cat (a “thought experiment” by Erwin Schroedinger) …or… . P. I. R ? ? ? 10

Inflation A rapid and dramatic phase of expansion shortly after the Big Bang blows up these quantum fluctuations and “freezes” them into the fabric of the Universe. These are the seeds of cosmic structure. 11

Points to Ponder • The Universe is Nature’s ultimate example of Schroedinger’s cat • Inflation is a very, very brief period of extremely rapid expansion in the infancy of the Universe • We have quantum mechanics and gravity to thank for the existence of galaxies like our Milky Way and indeed for our own existence 12

Prediction #1 Galaxy collisions should be common and easily visible 13

Computer Simulation of Colliding Galaxies 14

And This Is What We See…. . 15

Prediction #2 “Infant” galaxies should look different from mature galaxies 16

Zooming into Deep Space, Looking Back in Time 17

Zooming into Deep Space, Looking Back in Time 18

Distant Galaxies Are Small and Ragged Infant galaxy Young galaxy Mature galaxy 19

Deepest Image of Distant Galaxies 20

The Hubble Space Telescope is in orbit above the Earth’s atmosphere and so is able to take sharp pictures……but…. . it is prohibitively expensive to build telescopes that are based in space A new method called “Adaptive Optics” allows us to sharpen the vision of telescopes that are on the ground, by correcting for the blurring caused by the Earth’s atmosphere 21

Prediction #3 The farthest things we see should be the early seeds of galaxies 22

Early Seeds: Fluctuations in the Microwave Background Radiation Maps 23

Points to Ponder • Galaxy cannibalism is a common phenomenon in which small serve as building blocks from which larger galaxies are assembled • Telescopes are time-machines that enable us to peer into the Universe’s distant past • The after-glow from the Big Bang and early hot phase of the Universe is visible today and indeed even the wrinkles on the face of the early Universe are visible 24

Completing the Cycle…… Infant galaxy Spiral galaxy like our own Sun’s stellar ancestors You!planet & star Our Protein molecule 25