Final answer:
The Big Bang theory is supported by evidence such as the Cosmic Microwave Background Radiation, the redshift of galaxies, and the abundances of light elements like deuterium, helium, and lithium, which all indicate that the universe was hotter and denser in the past and has been expanding over time.
Step-by-step explanation:
Three forms of evidence that support the Big Bang theory are:
- Cosmic Microwave Background Radiation (CMB): The CMB represents the thermal radiation left over from the early universe and is considered the remnant heat from the Big Bang. Its blackbody spectrum is measured at a temperature of about 2.725 K and can be detected from any direction in space not obscured by another source. This is a compelling sign of the universe's creation in a massive explosion.
- Redshift of Galaxies: The observed redshift in the light from galaxies is an indication that the universe is expanding. The redshift is proportional to the distance of the galaxies from us, which means the farther away the galaxy, the faster it is moving away, thus suggesting that the universe has been expanding since the Big Bang.
- The abundance of light elements: In the early universe, the process of nucleosynthesis led to the formation of light elements such as deuterium, helium, and lithium. The relative abundances of these elements observed today match the predictions made by the Big Bang theory for a cooling and expanding universe.
Fossil records and plate tectonics are not related to the Big Bang and are used in other scientific fields such as biology and geology, respectively.