Dark Matter and Dark Energy: Current Understanding

TOPIC CLASSIFICATION

Subject: Science & Technology - Physics and Cosmology
Sub-topic: Dark Matter - Evidence (Galaxy Rotation Curves, Gravitational Lensing, CMB, Bullet Cluster), Candidates (WIMPs, Axions, Sterile Neutrinos, MACHOs, Primordial Black Holes), Detection Methods (Direct - XENON, LUX, DAMA; Indirect - Fermi GLAST, AMS-02; Collider - LHC), Dark Energy - Evidence (Type Ia Supernovae - accelerating universe), Cosmological Constant ((\Lambda)), Quintessence, (\Lambda)CDM Model, Hubble Tension
Mains GS Paper-III: Science & Technology - developments in physics and cosmology, their implications for fundamental science.

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EXAMINER REASONING

Dark matter and dark energy constitute 95% of the universe yet remain among the biggest open questions in physics. Prelims tests: evidence for dark matter (rotation curves, gravitational lensing, CMB), (\Lambda)CDM model, WIMPs, axions, dark energy evidence (Supernova Ia), cosmological constant, Hubble constant (H₀), LIGO India, India's contributions (INO, JAGUAR, TIFR dark matter lab). Mains demands: (a) the evidence for dark matter - Vera Rubin's galaxy rotation curves (1970s), gravitational lensing in the Bullet Cluster, Cosmic Microwave Background (CMB) anisotropy from Planck, (b) dark matter candidates - WIMPs (from SUSY), axions (from QCD), sterile neutrinos, MACHOs (brown dwarfs, black holes), (c) direct vs indirect detection - why dark matter has not been directly...