Georges LeMaitre theorized The Big Bang in 1927 two years before NOTES: Proofs of the Hot Big Bang (of Georges LeMaitre): 1. The red shift of distant galaxies. 2. The cosmic microwave background. Penzias and Wilson 1976. A black body curve at T = 2.7 K results from electrons combining with protons to make hydrogen. Ultraviolet stretched to microwave with the expanding universe. This has small lumps in different directions of about 1 part in 10,000 indicating early inflation. 3. Nucleosynthesis–Burbidge, Fowler, and Hoyle in 1960 calculated Big Bang made 75% He, 25% He–observed in unrecycled material. Georges LeMaitre theorized The Big Bang in 1927 two years before Hubble observed it.

Proofs of the Hot Big Bang: 1. The red shift of distant galaxies Implies Hubble’s Law

Proofs of the Hot Big Bang: 2. The cosmic microwave background. observed and identified by Penzias and Wilson in 1965. Predicted by Cosmologist George Gamov in 1948

A black body curve at T = 2.7 K results from electrons combining with protons to make hydrogen. Ultraviolet stretched to microwave with the expanding universe.

WMAP Satellite—observes the microwave Background. This has small lumps in temperature in different directions of about 1 part in 10,000 indicating early inflation.

Proofs of the Hot Big Bang: 3. Nucleosynthesis–in 1960 Burbidge, Burbidge, Fowler, and Hoyle calculated Big Bang made 75% H, 25% He–observed in unrecycled material.

For about a second, the Big Bang was hotter than 10 million K, and fused 25% of H into He.

The ‘primordial soup’ Was thus 75% H and 25% He by mass.

–A funny energy in space Post-1998 Cosmology –A funny energy in space At the present epoch the velocity of receding galaxies is given by Hubble’s Law: v = Ho d , where Ho is the Hubble constant. 1. This holds only for galaxies at moderately low distances.

In actuality, the straight line of Hubble’s law curves gently downward at greater distances as indicated by supernova Ia measurements of explosions up to about 11 billion years ago (Perlmutter’s and Schmidt’s groups --post 1998). Saul Perlmutter, Berkeley Brian Schmidt, Harvard (at first)

At first, it was East Coast vs West Coast!@*#!

a) The velocities are given by the redshifts of the galaxies they are in. b) The distances are given by standard peak luminosity of supernovae Ia, which is always the same.

The data implies the universe is speeding up.

The universal expansion is accelerating. It will expand forever in such a way that it implies: a) The mass in the universe is not sufficient to turn the expansion around, even with dark matter included, If I throw my keys up, they slow down. gravity normally decelerates!

b) There is a funny energy in space (usually called dark energy) driving the acceleration like a compressed sponge when released.

If Einstein’s General Theory holds, this energy may be in the form of Einstein’s cosmological constant, Λ. In 1917, he postulated that this constant outward force was necessary in a static universe to keep the galaxies from falling into each other. The universe was not found to be expanding until 1929.

Dark energy may also be a time varying component of space called quintessence--the fifth element. However, for now, data closely matches the cosmological constant.

Cosmic History

10-32 sec

1 second Big Freeze Out                                                                                                                               The First Atomic Nuclei

The decoupling era (recombination) Decoupling of light and matter. 380,000 years ABB (After Big Bang) D The decoupling era (recombination) H atoms can form, because light escapes.