UPSC Prelims 2012 · GS Paper I
Question 19: Science and Technology
Which of the following is/are cited by the scientists as evidence/evidences for the continued expansion of universe?
- 1.Detection of microwaves in space
- 2.Observation of redshift phenomenon in space
- 3.Movement of asteroids in space
- 4.Occurrence of supernova explosions in space
Select the correct answer using the codes given below :
AnswerUPSC’s answer is (a).
Two observations are cited for the expanding universe: the redshift of light from distant galaxies, which grows with distance (Hubble's law), and the cosmic microwave background, the relic radiation of a hot, dense early universe that fits an expanding model. The motion of asteroids is a local solar-system matter. Supernovae explode inside galaxies, so their mere occurrence says nothing about expansion.
- 1. The cosmic microwave background supports a universe that has expanded from a hot dense state.
- 2. Redshift of distant galaxies shows they are receding as space expands.
- 3. Asteroid movement concerns the solar system, not cosmic expansion.
- 4. The mere occurrence of supernova explosions is not evidence of expansion.
Why each option is right or wrong
- (a) Correct: microwave background and redshift are cited as evidence.
- (b) Incomplete: the cosmic microwave background is also cited.
- (c) Wrong: asteroid movement and the occurrence of supernovae do not show expansion.
- (d) Wrong: redshift and the microwave background are accepted evidence.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2012, General Studies Paper I, Series A. The paper on upsc.gov.in.