2. EARLY IDEAS ABOUT SPACE
• Until about 100 years ago
astronomers thought that
outer space was
unchanging.
• 1918-1929 Telescope
technology improved and
allowed astronomers to
observe many celestial
bodies that had never
been seen before.
4. • First astronomer to identify galaxies other than
our own (Milky Way)
• By 1929 Hubble had identified and estimated
distances of 46 galaxies
• He noted that the galaxies were not staying still,
but were moving away from each other
5. HUBBLE’S PROPOSAL
• Universe is expanding in all directions
• More distant galaxies are moving away faster
than near by galaxies
• Expansion is accelerating
• Path of expansion can be traced backwards and
galaxies appear to originate from the same
location
• Hubble based his proposal on evidence from red
shift analysis
6. RED SHIFT ANALYSIS
• Electromagnetic Radiation:
• Energy that is carried in the form of waves.
• Includes: Visable light, X-rays, radio waves, UV
radiation etc.
• Stars and galaxies emit different types of
electromagnetic radiation
7. SPECTRAL PATTERNS
• White light spits into bands of rainbow colours
when it passes through a prism
• The pattern of colours is called a spectrum
• Each colour of the spectrum represents a
specific wavelength
• A spectroscope is an instrument that allows the
observer to see the pattern of spectral lines
8. • Galaxies and stars emit characteristic spectral
patterns created by the elements they contain
9. COSMOLOGICAL RED SHIFT
• Hubble noticed that the spectrum from distant
galaxies appeared to have shifted toward the red
end of the spectrum.
• This change is due to a lengthening of
wavelengths as the galaxy move away from the
observer.
10. BIG BANG THEORY
• Hubble’s observations about galaxies
moving apart led astronomers to
hypothesize what the beginning of that
process must have been
• In 1927 Georges Lemaître proposed a
theory that stated the universe was
formed in a single dramatic moment of
expansion
• His theory was ridiculed and
sarcastically nicknamed the big bang
theory
• Evidence has since been collected to
support this theory and the name
stuck.
11. • Big Bang Theory: 13.7 billion years ago, a tiny
volume of space quickly expanded to a very
large size. In a short time, all matter and energy
were formed.
12. THE BIG BANG THEORY EXPLAINED
• http://youtu.be/DmUiCweDic4
13. EVIDENCE FOR THE BIG BANG THEORY
• Cosmic Background Radiation:
• Astronomers in the 60’s monitoring microwave
radiation in space picked up background noise or
interference. They concluded this was the left over
cosmic energy from the big bang
• Radiation: the transmission of energy in waves.
• As particles of gas were created in the early
universe, heat was produced in the form of
microwave radiation.
14. • Data gathered by the Cosmic Background Explorer
(COBE) and the Wilkinson Microwave Anistropy
Probe (WMAP) has helped corroborate the Big Bang
Theory.
15. WHAT WE KNOW SO FAR
• http://youtu.be/17jymDn0W6U
