Why in the news?

• Gamma-ray bursts emitted from tiny remnants of black holes could provide crucial insights into the nature of quantum gravity.

Quantum Gravity

• What is it?:
  • Quantum Gravity is the theoretical framework that seeks to unify General Relativity (gravity) with Quantum Mechanics.
  • It attempts to describe gravity according to the principles of quantum physics, where space-time itself becomes quantized at the smallest scales.
• Core Idea:
  • At the Planck scale, spacetime is not smooth but has a “quantum foam” structure- fluctuating and probabilistic.
  • The gravitational field, like other forces, should have quantum excitations called gravitons (hypothetical, massless, spin-2 particles).
  • These gravitons would mediate gravity in a quantum-mechanical way, similar to photons in electromagnetism.
• Significance:
  • Advances here contribute to fundamental physics, cosmology, and space research, with indirect implications for India’s astrophysics & ISRO’s cosmological missions.
  • Explain Big Bang singularity and early universe evolution.
  • Describe black hole information paradox.
  • Develop a unified theory of nature.
  • Inspire quantum computing and cosmology models.
• Challenges:
  • No experimental proof yet- effects appear at energies far beyond current technology.
  • Difficult to quantize spacetime because gravity acts on the very fabric that defines quantum fields.
  • Competing theories make differing predictions that lack consensus.
  • Bridging between macroscopic smoothness and microscopic discreteness remains unresolved.
• Indian Contributions:
  • IUCAA (Pune), TIFR, IISc, and Institute of Mathematical Sciences (Chennai) conduct research in quantum cosmology, loop quantum gravity, and black hole thermodynamics.
  • India participates in global collaborations like LIGO-India to study gravitational waves, a potential testing ground for quantum gravity theories.