Within ____ years from the Big Bang, temperature dropped to 4500K (Kelvin) and gave rise to atomic matter. The universe became transparent.
Show answer & explanation
Correct answer: A
Explanation
The correct answer is Option 1: 300,000.
Explanation:
- According to the Big Bang theory, within approximately 300,000 years of the universe's origin, a pivotal event occurred known as 'Recombination.'
- Drop in Temperature: During this period, the temperature of the universe dropped to approximately 4500 K (Kelvin).
- Formation of Atomic Matter: As the temperature decreased, electrons and protons were able to combine to form neutral atoms (primarily hydrogen and helium).
- The Universe Becomes Transparent: Prior to the formation of atoms, the universe resembled a 'hot fog' due to the presence of free electrons, which prevented light (photons) from escaping. Once atoms formed, light was able to travel unimpeded, and the universe became transparent. This very light is what we observe today as the Cosmic Microwave Background (CMB).
Key Stages of the Big Bang (Quick Revision):
- The Big Bang Event: Occurred approximately 13.8 billion years ago.
- The First 3 Minutes: During this period, the first atomic nuclei were formed (Nucleosynthesis).
- The Theory of Expansion: Edwin Hubble demonstrated that the universe is still expanding.
Important Questions for Upcoming Examinations:
Question: Who propounded the Big Bang theory?
Answer: Georges Lemaître.
Question: What is the evidence for the continuous expansion of the universe?
Answer: Redshift and Cosmic Microwave Background radiation.
Question: Which two elements are found in abundance in the universe?
Answer: Hydrogen and Helium.