Big Bang

Lesson Objectives:

• Recognize that the universe is expanding.

• Identify a model that illustrates the Big Bang theory.

• Create a model that shows how the universe is expanding.

The Universe

All existing matter and space considered as a whole; the cosmos. The universe is believed to be at least 10 billion light years in diameter and contains a vast number of galaxies; it has been expanding since its creation in the Big Bang about 13 billion years ago.

What's This Big Bang All About?

The Big Bang Theory is how astronomers explain the way the universe began. It is the idea that the universe began as just a single point, then expanded and stretched to grow as large as it is right now—and it is still stretching!

Before the Big Bang

• Scientists believe that before the Big Bang space and time didn't exist and all that existed was energy

• The Big Bang occurred when all of this energy was concentrated into a single point called 'singlularity'

• Space began to expand quickly and the temperature was hot (an estimated 100 million trillion trillion degrees!)

A Tiny, Hot Beginning

• When the universe began, it was just hot, tiny particles mixed with light and energy. It was nothing like what we see now

•  As everything expanded and took up more space, it cooled down.

A Tiny, Hot Beginning

• The first stars created bigger atoms and groups of atoms. That led to more stars being born.

• At the same time, galaxies were crashing and grouping together.

• As new stars were being born and dying, then things like asteroids, comets, planets, and black holes formed!

Expanding Universe

• The universe is still expanding

• If things were moving apart, it meant that long ago, everything had been close together

• Everything we can see in our universe today—stars, planets, comets, asteroids—they weren't there at the beginning.

Cosmic Microwave Background Radiation

• Big Bang Theory suggests that the universe was a very hot place and that as it expands, the gas within it cools 

• As the universe began to cool, radiation began to fill the universe as a remnant of the heat left over - this is called 'Cosmic Microwave Background'

• The cosmic microwave radiation is like an 'afterglow' of radiation

Evidence: Cosmic Background Radiation