In 2-3 sentences, summarize the evidence for the big bang theory. Include the following vocab words in your response: Redshift, Galaxies, Expansion, Cosmic microwave background.

The Big Bang theory is supported by experimental evidence obtained by astronomical observations. Scientists observing light emitted from galaxies did not match light spectra produced in experiments on earth - they were shifted to a longer wavelength, a phenomenon known as redshift. The only way that light could have been redshifted while it was traveling from the galaxies was if the galaxies were moving away from us by the universe’s expansion. Another observation is the faint electromagnetic radiation being emitted from the far reaches of the universe; this cosmic microwave background essentially provides a snapshot of the universe when the temperature dropped low enough for fundamental particles to form.

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