The Universe

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Slide 1

The Universe

Slide 2

Cosmology

Cosmology is the study of the nature of the universe, how the universe began and how it will end, if it does

There is religious cosmology, and scientific cosmology

“Creation myths” from traditional cultures are a form of cosmology

Scientific cosmology is part of astronomy and physics

Slide 3

Newton’s Static Universe

Here’s what Isaac Newton thought:

The universe is static (unchanging) and made of an infinite number of stars that are scattered randomly throughout an infinite space

The universe is infinitely old and will exist forever without any major changes

This is also called the “steady state” model

Is this true?

Slide 4

Edwin Hubble’s Discovery

Hubble noticed that the further away the galaxy, the greater the redshift of its light

Redshift is the Doppler Effect for light waves from objects moving away from the observer

Slide 5

What does this redshift mean?

The greater a galaxy’s distance from the observer, the greater its speed moving away from the observer, based on its greater redshift

So, galaxies are getting farther apart as time moves forward, therefore the universe is expanding (getting bigger)

Slide 6

How old is the universe?

Hubble showed that the universe has been expanding for billions of years

The universe was denser in the past

If we “run the film backwards” to when the universe was a single point in space and infinitely dense, that happened about 13.7 billion (13,700,000,000) years ago

This was the “Big Bang”

Slide 7

The Big Bang

Most scientists believe the universe as we know it began with the big bang

This created space and time as we know them, so in a real sense, there was no “before the big bang,” and the big bang didn’t happen “in space”

Slide 8

The expanding universe

The space between galaxies expands, not the galaxies themselves

Example: raisins in a loaf of bread.

As the overall loaf of bread expands, the space between raisins increases but the raisins themselves do not expand.

Slide 9

Dark energy and dark matter