1. It seems the universe began with an explosion
Rainer Weiss
Newton Free Library
February 28, 2008

2. Churning of the milky ocean
Asuras
Shankha
Vishnu
Uchchaisravas
Surabhi
Vasuk
Turtles all the way
Mandan mountain churn
Devas

3. Olber’s Paradox Why is the sky dark at night?
Night sky in Arizona
All lines of sight hit a star

5. Geometric methods Eratosthenes measurement of Earth’s radius (240BC)
Parallax of comet Hyakutake

7. January
July

8. Distance from intensity
Types of stars : the HR diagram
Finding more powerful standard “candles”
Intensity of star at observer vs distance
Intensity ~ 1/distance 2

9. Henrietta Leavitt at Harvard Smithsonian (~1910)
Cepheid variables
important
Henrietta Leavitt at Harvard Smithsonian (~1910)

10. Supernova “standard candles”
Outshine an entire galaxy for a few days
Occur about once every 100 years in a typical galaxy

11. Spectroscopy of star light
Spectrometer placed at output of a telescope provides information about the composition of a distant object.
Spectrum of an atom is a unique signature
A hydrogen atom on the Earth is the same as one in a distant galaxy

12. Red (longer wavelength) shift of the spectral lines of atoms with distance
Dl/l G ly
Ursa Major
Corona Borealis
Bootes
Hydra

13. Hubble Diagram redshift vs distance
Edwin Hubble
More distant

14. Interpretation of the red shift with distance
CHARACTERISTICS
Dl/l independent of the wavelength
does not depend on direction in the sky
does not depend on the type of object
WHAT IT ISN’T DUE TO
Light becoming tired
Change in the fundamental constants of nature with distance (and time)
DOPPLER INTERPRETATION
Stretch or compression of waves by moving away from or toward source
One way
The other way

15. Profound implications of the Doppler Interpretation
Universal expansion – homogeneous and isotropic
Relative velocity proportional to separation
There is a beginning when it was very dense
The age of the universe is 13.7 G years
The expanding universe is a solution in Einstein’s General Relativity

16. The explosion was hot at the beginning
Holmdel, New Jersey antenna used by Penzias and Wilson in measuring noise from the universe ( )
Dicke radiometer
Temperature now 3K, 13G yrs ago 10000K

17. Spectrum of a hot thing --- thermal Planck spectrum

18. Scale should read 1/wavelength
Thermal spectrum curves progressively colder
Scale should read 1/wavelength
Cosmic background radiation spectrum from COBE (J. Mather, Nobel Prize 2006)
Universe was in thermal equilibrium until ~ years after the primeval explosion

19. Thermal equilibrium -- featureless homogeneity and isotropy

20. COBE sky COBE 7 angle deg 3K 3 milliK 10 microK 10 microK
Dipole due to our motion in the universe
3 milliK
10 microK
with galaxy in
10 microK
WMAP angle deg
Quantum fluctuations inside the primeval kernel frozen in by dark matter !!!!!

21. Dark matter (blue), atoms (red)
What is it?
WMAP modeling results
Colliding galaxies
W = 1
What is it?
Dark matter (blue), atoms (red)
Vera Rubin found dark matter in galaxies
Galactic cluster

22. History of the universe (2008)

23. Large Scale Structure of the Universe
Gravitation of dark matter – our version of the churn
Sloan survey large scale structure: grown from the seeds of the primeval quantum fluctuations. The population of the blue distance chart from the beginning of the talk.
Thank WGBH for “Whisper from Space”