Theories about the universe

Theories about the universe

1. There are two different theories about the universe

   • The Big Bang Theory
     • Says that the whole universe started out as a tiny particle about 13.5 billion years ago. The universe expanded from this point in space. The universe is still expanding today.
   • The Steady State Theory
     • Says that the universe has always existed. It is expanding, and new matter is being created as it expands

2. Red Shift

   • If a vehicle with a siren goes past you. you can hear the sound change. The movement of the siren changes the frequency and wavelength of the sound waves that you hear
   • A similar effect happens with light. Black lines in the spectrum of light from a star are moved closer to the red end of the spectrum if the star is moving away from us. This is called red shift.
   • The further the lines are shifted, the faster the object is moving away
   • Light from distant galaxies shows red-shift. The more distant the galaxy the greater the red-shift. This shows that the universe is expanding. Red-shift supports both theories, as both theories say the universe is expanding