Comparing cooling temperature changes at different stages of the universes life provides evidence of the radiation generated by The Big bang expansion

Answer 1

The cooling temperature changes throughout the universe's history provide significant evidence supporting the Big Bang theory, particularly through the study of cosmic microwave background radiation (CMB). Here's how these cooling changes align with the Big Bang expansion theory:

Early Universe

• Initial Conditions: The universe began as an extremely hot and dense singularity. As it expanded, the temperature was incredibly high, allowing for the formation of elementary particles like quarks.
• Cooling Phase: As the universe expanded, it cooled rapidly. A few microseconds after the Big Bang, temperatures fell enough for quarks to combine into protons and neutrons.

Nucleosynthesis

• Formation of Light Nuclei: Around three minutes after the Big Bang, temperatures dropped to about a billion degrees Kelvin, allowing protons and neutrons to fuse, forming light nuclei (like hydrogen, helium, and trace amounts of lithium).
• Decreased Temperature: As the universe continued to expand, temperatures decreased further, leading to a transparent universe where photons could travel freely after approximately 380,000 years.

Cosmic Microwave Background

• Formation of CMB: When the universe cooled to around 3000 K, electrons combined with protons to form neutral hydrogen, allowing photons to decouple from matter. This event is known as "recombination."
• Radiation Emergence: The radiation released during this epoch has now cooled to about 2.7 K and is observed as the CMB, uniformly distributed across the universe.

Current Observations

• Redshift and Temperature: As the universe continues to expand, the wavelengths of the photons from the CMB are redshifted, which is evidence of the universe's ongoing expansion and cooling.
• Thermal History: The temperature fluctuations and anisotropies in the CMB provide insights into the structure formation of the universe, confirming predictions made by the Big Bang model.

Conclusion

The cooling temperature changes throughout the universe—especially as evidenced by the CMB—strongly support the Big Bang theory by illustrating a gradual decrease in thermal energy and providing a relic signature of the universe's hot and dense beginnings. Through this framework, scientists can analyze and estimate the age, composition, and evolution of the universe.