The Universe is defined as the summation of all particles and energy that exist and the space-time in which all events occur. Based on observations of the portion of the universe that is observable, physicists attempt to describe the whole of space-time, including all matter and energy and events which occur, as a single system corresponding to a mathematical model.

## Big Bang Theory

- Define
- Evidence

- LeMaitre
- Hoyle elements form in stars
- Doppler Effect - Red shift
- Penzius and Wilson- Cosmic Background Radiation

## Inflation Theory

## Open-Closed Universe debate

- Entropy -
- Omega -
- Open -
- Closed -

## links

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