The idea
The evidence points to a universe that began in an extremely hot, dense state about 13.8 billion years ago and has been expanding ever since.
Three independent lines of evidence
- Redshift. Light from distant galaxies is stretched toward red, and the farther away a galaxy is, the more it is stretched. Space itself is expanding.
- Cosmic microwave background. A faint glow at the same temperature in every direction — the leftover heat of the early universe, cooled by expansion to about .
- Abundance of light elements. The proportions of hydrogen and helium we measure match what the theory predicts should have formed in the first few minutes.
Why three matters more than one
Redshift alone could have other explanations. Redshift and a uniform background glow and the exact element ratios, all predicted in advance by the same model, is a different level of evidence entirely.
A common misunderstanding
The Big Bang was not an explosion into empty space. There was no outside. Space itself expanded — and still does, everywhere, all at once.
Diverse ways of knowing
Cultures around the world, including First Nations, Métis, and Inuit peoples, have long traditions of observing and explaining the night sky. Many encode real observational knowledge — seasonal star positions used for navigation and timing. Understanding how different knowledge systems record and pass on observations is part of what this course asks of you.
Curriculum connection
E2.3
summarize observational evidence used to support theories about the origin and evolution of the universe and the solar system, considering diverse ways of knowing
Link to original
A2.5
analyse contributions to science by people from various communities, including communities in Canada
Link to original