History of the Universe 19 6 The Beginning

History of the Universe 19. 6

The Beginning of the Universe Evidence suggests that the universe is expanding. The Big Bang Theory – an enormous explosion 13. 7 billion years ago that caused the expansion and cooling of everything in the universe. This cooling started the formation of atoms, stars, and eventually galaxies.

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How do we know the universe is expanding? • The Doppler Effect – As objects move toward the observer the sound waves and lights waves compress creating shorter wavelengths • Shorter wavelengths of light appear blue – As objects more away from the observer the sound waves and light waves decompress creating longer wavelengths • Longer wavelengths of light appear red

Hubble’s Law • In the 1920’s, Edwin Hubble discovered that the light coming from most galaxies was undergoing a red shift indicating that most were moving away from earth. – The farther away the galaxy the greater the red shift. • Hubble’s Law states that the speed at which a galaxy is moving away is proportional to its distance from us.

Hubble’s Conclusion • Most observed galaxies appear for show red shift, therefore the universe is expanding.

Technology that Aids Space Exploration • Telescopes – Visual – use visible light – Radio – use radio waves to retrieve information from space probes. – X-Ray – use shorter wavelength than visible light • Computers managing data. • Space Probes collect information and materials.

Hubble Telescope - 1990