The information that scientists can gather about the early universe is in the form of light from distant galaxies. This light requires millions of light years to reach earth. If we can see the most distant galaxies, we can observe conditions in the early universe. Scientists analyze galaxy spectra to infer how the universe began. The current prevailing theory of the origin of the universe is called the big bang theory, which states that the universe began in a massive explosion of an extremely dense, hot ball of matter approximately 13.7 billion years ago.
1. Open the Shifting Light Spectra activity. When prompted, use the slider to move the galaxy as directed. Describe how the galaxy's spectrum changes as
it moves away from and toward the blue planet.
2. When prompted, explore further. Select each galaxy to see its spectrum. Select blue or red to indicate if the galaxy's spectral lines show redshift or blueshift. Then choose whether the change in spectral lines would indicate a
diverging and expanding universe or a converging and shrinking universe.