How Do We Actually Know the Big Bang Happened?

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How do we actually know the Big Bang happened?
In this video, we follow the chain of evidence step by step, from measuring the distances to stars and galaxies, to redshift, cosmic expansion, and the discovery of the cosmic microwave background. This is the story of how light, physics, and careful observation revealed that the universe began in a hot, dense state.

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Sources, References and Further Reading:

Weinberg, S. The First Three Minutes: A Modern View of the Origin of the Universe. Basic Books. https://www.basicbooks.com/titles/steven-weinberg/the-first-three-minutes/9781668612149/

Singh, S. Big Bang: The Origin of the Universe. Fourth Estate / HarperCollins. https://books.google.com/books/about/Big_Bang.html?id=AWjLAAAACAAJ

Krauss, L. M. A Universe from Nothing: Why There Is Something Rather than Nothing. Simon & Schuster / Free Press. https://www.simonandschuster.co.uk/books/A-Universe-From-Nothing/Lawrence-M-Krauss/9781471112690

Gribbin, J. 13.8: The Quest to Find the True Age of the Universe and the Theory of Everything. Yale University Press / Icon Books. https://books.google.com/books/about/13_8.html?id=1v6oCwAAQBAJ

Pharaoh, L., Bishop, C., and Gidzewicz, C. AQA A-Level Physics Year 2 Student Book (includes Astrophysics). Collins. https://collins.co.uk/products/9780007597642

Liddle, A. An Introduction to Modern Cosmology. Wiley. https://www.wiley.com/en-us/An%2BIntroduction%2Bto%2BModern%2BCosmology%2C%2B4th%2BEdition-p-9781118502143

Olesen, P. An Introduction to Cosmology. Lecture notes / article. https://cds.cern.ch/record/366328/files/p220.pdf

Ryden, B. Introduction to Cosmology. Cambridge University Press. https://www.waterstones.com/book/introduction-to-cosmology/barbara-ryden/9781107154834

Reid, D. D., Kittell, D. W., Arsznov, E. E., and Thompson, G. B. “The Picture of Our Universe: A View from Modern Cosmology.” https://ned.ipac.caltech.edu/level5/Sept02/Reid/paper.pdf

Morison, I. Introduction to Astronomy and Cosmology. Wiley. https://books.google.com/books/about/Introduction_to_Astronomy_and_Cosmology.html?id=UVydyI8XKBgC

Roos, M. Introduction to Cosmology. Wiley. https://books.google.com/books/about/Introduction_to_Cosmology.html?id=EOI-MNHKWFsC