Correct Option
The correct option is 1 and 3 only.
Explanation
The Big Bang Theory is the prevailing cosmological model for the universe from the earliest known periods through its subsequent large-scale evolution. It describes how the universe expanded from an initial state of high density and temperature.
Statement-wise Analysis
- Statement 1 is Correct: The Big Bang Theory is popularly known as the expanding universe hypothesis. It suggests that the universe is not static but is constantly expanding in all directions.
- Statement 2 is Incorrect: Edwin Hubble provided evidence for the expansion of the universe in 1920 (specifically 1929), not 1850. He observed that the redshift of distant galaxies increased with their distance from Earth, implying they were moving away.
- Statement 3 is Correct: The theory posits that the space between galaxies is stretching, which increases the distance between them. However, the galaxies themselves (and the solar systems within them) are held together by gravitational forces and do not expand in size.
Key Takeaway: While the universe expands, causing the distance between galaxy clusters to increase, individual gravitationally bound structures like galaxies, stars, and planets do not expand.