The “Big Bang” Theory

Birth of the Universe

The Big Bang Theory

• First and foremost – THIS IS A THEORY!– It is up to you whether you want to believe it– However, you MUST learn it

• Any Questions??

The Big Bang Theory

– Most accepted scientific theory of creation of the universe– The universe began as a incredibly small concentrated point of energy

that was extremely dense and extremely hot.– From this point, called a singularity, the universe began to rapidly

expand outward.

The Big Bang Theory

•As the universe expanded, it began to cool down.•It is believed that protons, neutrons and electrons formed within minutes of the Big Bang.•As the universe continued to cool, matter began to form.•Gravity pulled atoms together.•Galaxies and stars were formed in this way.

The Big Bang TheoryEvidence for The Big Bang:• Red Shift:

– When light is moving towards or away from an observer, its wavelength changes. It shifts more toward the blue(shorter)wavelengths when it moves closer, and more toward the red (longer) wavelengths as is moves away. Edwin Hubble found that light from most galaxies undergoes a red shift, meaning that the galaxies are moving away from earth, supporting the idea of an expanding universe.

• Hubble’s Law: The speed at which a galaxy is moving away is proportional to its distance from us. The further the galaxy is from us, the faster it is moving away from us.

The Big Bang TheoryEvidence for the Big Bang:• Cosmic Background Radiation:

– Steady microwave radiation from space– Thought to be left over from Big Bang

The Big Bang Theory• Since astronomers know how fast the universe is expanding, they have

deduced that the universe is between 13 and 14 billion years old!• It is believed that the universe will continue to expand.• Scientists believe that the universe is expanding faster then before.