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space hard MCQ

The Sachs-Wolfe effect describes CMB temperature fluctuations caused by which phenomenon?

Doppler shift
Gravitational redshift/blueshift
Thomson scattering
Synchrotron emission

Answer: Gravitational redshift/blueshift

Photons climbing out of potential wells lose energy (redshift); falling in gain energy (blueshift), imprinting primordial density perturbations on CMB.

Topic Astronomy - Cosmology

Exam Relevance UPSC Prelims, General Science

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