The Big Bang Theory https://vimeo.com/13974273 Big Bang Theory Video, W drive, Science, Grade 9 Science, Academic 9 Science

Think of crime scene investigations! Did the detectives see the explosion? No! They have to figure it out from evidence!

That is what astronomers do! They take evidence from space to figure out the science!

If the Universe is expanding, at some time it must have been concentrated in a single point.

Some sort of “event” occurred to cause the change that formed the universe we have today. Astrophysicists are struggling with this right now.

This event is what scientists call the "The Big Bang"

The Big Bang Theory states that universe formed in a single moment, when a dense point suddenly and rapidly expanded creating all matter and energy. That moment was the beginning of the universe. Approximately 13.7 billion years ago.

Not like an explosion where debris flies off into space!

expansion of space and time itself, Instead, it was the expansion of space and time itself, and therefore occurred everywhere at the same time. This is the really really hard part to understand.

Astronomers think that answer is yes. We just can’t see them. Are there galaxies beyond what we can see? Astronomers think that answer is yes. We just can’t see them. Of course you would not expect students to memorize “cosmic particle horizon” but it is such a cool term. Everything outside the horizon cannot be perceived by us.

What evidence do we have supporting the Big Bang?

Universal red shift

Red shift is is a form of the Doppler Effect. Sound shows Doppler effect too! Click on sound byte to hear effect. Click on the picture and have your sound on to here the Doppler effect!

Doppler Effect In the 1800s, Christian Doppler discovered that when the source of a sound wave is moving, its frequency changes. The change in sound you hear is caused by a Doppler shift. Doppler shift is related to the net change between the source of the waves and the observer.

What you just heard was the Doppler effect with sound What you just heard was the Doppler effect with sound. Red shift is the Doppler effect with light. If you are connected to the server, click on the hyperlink for an explanation of red and blue shift.

Notice that the line groupings are the same – only shifted red.

http://www.youtube.com/watch?v=Kg9F5pN5tlI http://www.youtube.com/watch?v=FhfnqboacV0

Doppler shift also occurs with electromagnetic waves, such as visible light, X-rays, and microwaves. This phenomenon is an important tool used by astronomers to study the motion of objects in space.

From our position in the universe, it looks like we are the center because everything appears to be moving away from us. But we are not in the center.

As a balloon gets larger every point moves away from every other point.

The second evidence is Cosmic Microwave Background Radiation!

This is energy “left over” from the Big Bang. -discovered in the early 1960’s.

This is like an oven that was used to make cookies This is like an oven that was used to make cookies. The cookies are not visible but the smell is there (evidence) and when you open the oven door there is just a little bit of heat still there (another piece of evidence).

Further Evidence for the Big Bang theory The proportion of hydrogen to helium is consistent with the physics of the Big Bang. If the universe were significantly older, there would be more heavy elements present compared with hydrogen and helium.

What Happens Next? Astronomers feel that the Big Bang theory leads to two possible futures for the Universe.

Open Universe Galaxies will continue racing outward (continue to expand). All of the stars will die off as the last of their energy is released. There will be nothing left, total emptiness.

Closed Universe Gravitational attraction between the galaxies will cause the movement away from each other to slow and, eventually come to a halt. The gravitational pull will begin to pull the galaxies back to the center of the universe.

Closed Universe continued All of the matter and energy will again come close together and end in a central area (possibly no larger than a dime). Then another Big Bang will occur and the formation of the universe will begin all over again.

Um… I think we may have been here before. This restructuring may occur once every 80 to 100 billion years