Origins of the Universe

What we know We know that stars are not fixed in place in the universe They are moving rapidly apart. This means the universe is expanding If something is expanding it must have come from somewhere. That somewhere is the Big Bang

But how can we tell how fast stars move? When something that emits waves moves the waves in front of the object get compressed and the waves behind get spread out You notice this when a car or train passes you. The sound has a higher pitch before it gets to you and a lower after it passes. This is called the Doppler effect

Ok but these are stars not cars? For light the colour of light depends on the length of the waves Red light has a long wavelength Blue light has a short wavelength

And?... If a star is moving away from us its waves are stretched and it appears more RED (RED SHIFT) If a star is moving towards us its waves are squished and it appears more BLUE (BLUE SHIFT)

And Finally the Point When we look into the sky all the stars we can see are red shifted. The farther a star is from us the more it is red shifted The only explanation for that is if everything is moving away from us. This means the universe is expanding

But where does it come from Since the universe seems to be expanding outwards it is logical to assume that it started at a point The Big Bang theory states that the universe began in a giant explosion 14 billion years ago

But the galaxies didn’t pop out like that right? Steps after the big bang 1)Energy cooled to form matter 2)First stars formed 3)Galaxies formed We are a second or third generation star

Proof of the big bang theory Expansion –We know from red shift the universe is expanding Leftover heat –Looking out at the sky we can still see that there is some heat left over from the giant explosion

Where next? Honestly we don’t know We could stop expanding and collapse back (big crunch) We could keep expanding till everything is so far away that there is no heat left (big chill) Or we could be eaten by a giant space duck…