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Electromagnetic Spectrum. Different Types of Light . Light is a form of energy It travels in waves Also called Electromagnetic Radiation Some Electromagnetic Radiation we can see (Visible Light), but most we cannot (Radio, Microwave, Infrared, Ultraviolet, X-Ray and Gamma Rays) .
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Different Types of Light • Light is a form of energy • It travels in waves • Also called Electromagnetic Radiation • Some Electromagnetic Radiation we can see (Visible Light), but most we cannot (Radio, Microwave, Infrared, Ultraviolet, X-Ray and Gamma Rays)
Spectral Lines • http://www.youtube.com/watch?v=l4yg4HTm3uk&feature=related
Spectral Lines • White light can be broken into all the colours in the visible spectrum
Spectral Lines • When we look at the spectrum of stars, there are parts of the spectrum missing. • These parts are missing because of the gasses present • These gases absorb specific spectrum of light
Hubble’s Second Great Discovery • Hubble observed that galaxies are moving away from each other. • He made this observation using the spectrum (rainbow) of light from stars in distant galaxies. • He applied a basic property of waves (of light and sound) called the doppler shift or red shift.
Doppler Red Shift • The way we see light from stars is affected by their speed and direction of motion • Red shift – Moving away from us • Blue shift – Moving towards us. • Red Shift Video URL • Hubble used this idea to discover that most galaxies are moving away from us and that the universe is expanding.
Doppler Red Shift • When light is shifted towards red • The object is moving away • The amount of shift is related tothe speed • When light is shifted towards blue • The object is moving closer • The amount of shift is related tothe speed
The Doppler Effect • http://www.youtube.com/watch?v=Y5KaeCZ_AaY • http://www.youtube.com/watch?v=-t63xYSgmKE&feature=related
Hubble’s Second Great Discovery • Hubble observed that galaxies are moving away from each other. • He deduced that the universe is expanding (and that space itself is expanding like the surface of a balloon.) • He predicted that all galaxies must have been very close to each other at an earlier time in the history of the universe. • This prediction led to the “Big Bang Theory”.
Questions • Read • 372 to 375 • 377 to 380 • Questions • Page 376: #1, #3, #4, #7 • Page 379: #1, #3, #4
Questions • Read Pages 372 to 375 • What is the major evidence that confirms the big bang theory? What does this evidence mean? • Compare and contrast COBE and WMAP. Explain what they show. • According to the big bang theory, in what ways was the early universe different from today? • What does the big bang predict about the future of the universe?