UPSC CSE Prelims
Question 74
Which of the following is/are cited by the scientists as evidence/evidences for the continued expansion of universe?
- Detection of microwaves in space
- Observation of redshift phenomenon in space
- Movement of asteroids in space
- Occurrence of supernova explosions in space
Select the correct answer using the codes given below:
View correct answer and explanation
Correct answer: A
Correct Option: A
Explanation: Cosmic redshift supplies direct observational evidence of expansion; the cosmic microwave background supports the expanding Big Bang framework.
Statement/Item-wise Analysis:
1: Correct - The cosmic microwave background is relic radiation predicted by the early expanding universe.
2: Correct - Distant-galaxy redshift shows systematic recessional expansion.
3: Incorrect - Asteroid motion reflects local Solar System gravitational orbits, not universal expansion.
4: Incorrect - Supernova events alone are not generic evidence of expansion without redshift/distance measurements.
Option-wise Analysis:
A: Correct - includes exactly the valid statements/items and excludes the invalid ones.
B: Incorrect - omits correct item 1.
C: Incorrect - includes incorrect items 3, 4; omits correct item 2.
D: Incorrect - omits correct items 1, 2.
Review Note: Microwave background is evidence for Big Bang cosmology, whereas galaxy redshift directly establishes continuing expansion.