Universe Formation Lecture 1 for HPU NCS2200 Earth Science for Elementary Education majors

1. Chapter 24 – Stars, Space,
and Galaxies
Earth Science and the Environment (4th ed)
Thompson & Turk

2. 24.1 In the beginning: The Big Bang
►Theory proposed by Georges Lemaitre in
1927 based on Einstein’s theory of general
relativity
 Derivation of the “Freidman equations” showed
that the universe was expanding – not static as
Einstein proposed
►In 1929 Edwin Hubble– observed that all
galaxies were moving away from one
another
 By plotting these motions, he surmised a
common starting point and time

3. Big Bang Theory con’t
► Theory was further supported by George Gamow
who introduced the Big Bang Nuecleosynthesis
 BBN explains the formation of the heavy
isotopes of hydrogen formed in the first
moments of the Big Bang
► Additional evidence was provided by Herman and
Alpher who predicted the presence of Cosmic
Microwave Background Radiation (CMBR)
 The presence of CMBR was confirmed in 1964 by Bell
Laboratories employees Penzias and Wilson.

4. Big Bang Theory
►Additional evidence was provided by the
presence of the elements Hydrogen, Helium
and Lithium in abundance throughout the
universe.

5. 24CO, p.607

6. 24.1 The Big Bang Timeline
►Just after T=0, temperature ~100 billion
Kelvin
 Universe about the size of a grapefruit
►A full second goes by and it cools to 10
billion K
 Still no atoms, just radiant energy and
subatomic particles
►Within a few minutes, nuclei as big as
Helium begin to fuse together (and fall back
apart)

7. The Big Bang Timeline
►By 10 minutes it had cooled so much that
fusion couldn’t occur, still only nuclei
 Helium stuck around – primordial
nucleosynthesis, and a trace of Lithium
►No nuclei any larger: no carbon, nitrogen, oxygen,
etc.
 By 300,000 years, all had cooled to a few
thousand degrees and electrons “stick” to nuclei
 Cosmic background radiation – the expected
“original photons” radiate at 2.7K

8. Fig. 24.1, p.609

9. 24.2 the Nonhomogenous universe
►Initial data suggested that since the CMBR
was uniform throughout space that the
Universe was homogenous at birth
►However, space is lumpier than one might
guess
 Galaxies, stars, etc. are clumps of matter
 The “really young” universe had waves of
energy that became clumps of mass during
cooling

10. Fig. 24.3, p.611
A three-dimensional, computer-generated drawing of a portion of the Universe

11. Support for Big Bang Theory
►Three pieces of evidence:
 Red shift of galaxies
 Cosmic Background Radiation CMBR)
 Abundant elements

12. Red Shift
► Doppler Effect states that – waves from a moving
object gather in the direction of motion, shifting
the wavelength
 Red shift – objects moving away from the observer
(position 2), the waves lengthen, move towards the red
end of the spectrum
 Blue shift – objects moving toward the observer
(Position 1) become shorter, or “bluer”

13. ► To understand red shift one must understand the
Eletromagnetic spectrum
 Wavelengths of energy emitted by a body
Red Shift

14. Red Shift: Spectra
►Visible light spectrum – an ordered array of
colors exhibited by light diverging through a
prism
 Two types of light spectra:
►Emission and absorption spectra
 Absorption spectrum – atoms in a stars exterior
absorb certain wavelengths, creating a pattern
of black absorption bands
 Emission spectra – when an atom absorbs
radiation, it must eventually reemit it as a
pattern of colored lines.

15. Fig. 22.31, p.577

16. Fig. 22.32, p.577

17. Fig. 22.33, p.578
Red Shift
► Emission spectra lines are shifted by
movement of the emitting body

18. Support for Big Bang Theory
►Cosmic background radiation – the expected
“original photons” radiate at 2.7K,
 In 1965, two young radio astronomers, Arno
Penzias and Robert Wilson, almost accidentally
discovered the CMB using a small, well-
calibrated horn antenna.

19. Support for the Big Bang:
Lighter Elements
► The wide distribution of
Helium (He), Hydrogen
(H) and Lithium (Li) is
also evidence that
supports the Big Bang
theory. These elements
are found in nearly
every part of our
universe – in stars,
planets, gas clouds
(nebulae) and even in
space dust!
Helium Hydrogen Lithium
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