Mysteries of the Universe: Key Unknowns

1. Dark Matter – The Invisible Mass

• Makes up ~27% of the universe but does not emit, absorb, or reflect light.

• Detected through gravitational effects on galaxies and cosmic structures.

• Leading candidates: Weakly Interacting Massive Particles (WIMPs), axions, and sterile neutrinos.

• Alternative theories: Modified Newtonian Dynamics (MOND) and emergent gravity.

• Ongoing searches: Large Hadron Collider (LHC), underground detectors (LUX-ZEPLIN, XENONnT), and astrophysical observations (gravitational lensing).

2. Dark Energy – The Force Behind Cosmic Expansion

• Composes ~68% of the universe, driving its accelerating expansion.

• Discovered through supernovae observations in the late 1990s.

• Possible explanations:

  • Cosmological Constant (Λ): A vacuum energy inherent to space.

  • Quintessence: A dynamic, evolving energy field.

  • Modified Gravity: The laws of gravity may differ on cosmic scales.

• Studied via cosmic microwave background (CMB), large-scale galaxy surveys (DESI, Euclid), and gravitational waves.

3. The Nature of the Early Universe & the Theory of Everything

• Unification of quantum mechanics and general relativity remains unresolved.

• Big Bang & Inflation: What caused inflation, and did it ever stop completely?

• Singularity & Black Holes: Do singularities exist, or does quantum gravity prevent them?

• Multiverse Hypothesis: Is our universe one of many?

• Baryon Asymmetry: Why does the universe contain more matter than antimatter?

• Probes include cosmic microwave background (Planck, JWST), particle physics experiments, and gravitational wave astronomy.