What is this? PH1600: Introductory Astronomy Lecture 22: In the Beginning …

What is this?

PH1600: Introductory AstronomyLecture 22: In the Beginning …

PH1600: Introductory AstronomyLecture 21: The Beginning of Our UniverseStudy: Chapter 19 in The Cosmos book Next Lecture: Chapter 19: Early Forces & Inflation

School: Michigan Technological UniversityProfessor: Robert Nemiroff

Book: The Cosmos by Pasachoff & FilippenkoOnline Course WebCT pages:

http://courses.mtu.edu/

This class can be taken online ONLY, class attendance is not required!

You are responsible for…

Reading the book One chapter per “quiz period” Anything from that chapter can appear on

quizzes or tests, even if I never mention them during my lecture(s)

This quiz period covers Chapters 18 APODs posted during the semester

APOD review every week during lecture Completing the Quizzes

Chapter 1, 2, 4, 6, 7, 8, 10, 11, 13, 14, 15 & 18 quizzes already due

Chapter 19 quiz due next See WebCT at http://courses.mtu.edu/ for

details

Universe Beginning: Steady State of Big Bang?

Steady State Universe Perfect cosmological Principle: universe

does not evolve with time Big Bang Universe

Universe evolves in time Cosmological Principle: universe looks

the same from every location

Microwave Background Radiation

Penzias & Wilson try to map Galaxy radio emission with horn shaped antenna

Find strange hiss in all directions Can’t eliminate it

Not warm pigeon poop Can’t explain it

http://www.phys.lsu.edu/~tohline/astr1102/Pics/Fig28-05.jpg

Horn Antenna used by Penzias and Wilson to detect the cosmicmicrowave background radiation.

Microwave Background Radiation

Photons from when the universe was only 400,000 years old

Originally 3000 K, now only 2.7 K Show that Earth is moving with

respect to CMBR Spot distribution shows universe is

70% dark energy, 13.7 billion years old

CMBR Dipole: Speeding Through the UniverseCredit: DMR, COBE, NASA, Four-Year Sky MapAPOD: 2006 October 8

COBE All-Sky MapCredit: COBE Project, DMR, NASA APOD: 2006 October 7

Antarctica Hears Little Normal Matter in the Big BangCredit & Copyright: DASI, CARA, NSF APOD: 2001 May 1

The Race to Reveal Our UniverseCredit: BOOMERANG Project, NSF APOD: 2000 May 9

WMAP Resolves the UniverseCredit: WMAP Science Team, NASA APOD: 2005 September 25

The Big Bang

t<10-43 seconds Planck epoch Before Planck epoch, the general

relativity description of spacetime breaks down.

No one knows what happens before 10-43 seconds

The Big Bang: Energy Everywhere

10-43 < t < 10-6 seconds Universe expands and cools 1032 < T < 1013 Kelvin Radiation epoch

All particles have speed near light Nuclei not stable

Broken apart soon after forming

The Big Bang: Particles Freeze Out

10-6 < t < 1 second Universe expands and cools 1013 < T < 1010 Kelvin Protons, neutrons, electrons,

positrons now frozen in All particles have speed near light

Nuclei not stable Broken apart soon after forming

The Big Bang: Nuclei Freeze Out

1 < t < 100 seconds Universe expands and cools 1010 < T < 1013 Kelvin Nuclei become stable Primordial nucleosynthesis

Determines what nuclei remain in the universe

Universe mostly hydrogen & helium

The Big Bang: Nuclei Become Atoms

t = 400,000 years Universe expands and cools T = 3000 Kelvin Recombination

Atoms become stable Nuclei able to retain electrons

Photons fly free for first time Still flying – form microwave

background radiation today

The Big Bang: Formation of Stars and Galaxies

400,000 < t < 4,000,000 years Dark Ages Stars not yet formed

4 million years < t < 13.7 billion years

Stars form, galaxies form Universe cools to 3.7 Kelvin

http://en.wikipedia.org/wiki/Image:Universe_expansion.png

Inflating the UniverseCredit: WMAP Science Team, NASA APOD: 2006 March 23

http://en.wikipedia.org/wiki/Image:Cosmological_composition.jpg

The Big Bang: Epochs

Radiation dominated Photon-like energy most abundant t < 300,000 years

Except for brief inflationary epoch

Matter dominated Atoms, molecules, dark matter most abundant 300,000 < t < 5 billion years

Dark energy dominated Now (barely)

The Hubble Deep FieldCredit: R. Williams, The HDF Team (STScI), NASA

APOD: 2002 September 1

The Andromeda Deep FieldCredit: T. M. Brown (STScI) et al., ESA, NASA APOD: 2003 May 19

HUDF: Dawn of the GalaxiesCredit: R. Windhorst (ASU), H. Yan (SSC, Caltech), et al., ESA, NASA APOD: 2004 September 29