1. Introduction to Cosmology

Cosmology is the scientific study of the origin, structure, evolution, and eventual fate of the universe. It combines physics, astronomy, and mathematics to understand large-scale properties and phenomena.

2. Historical Development

Ancient Views

  • Babylonian, Greek, and Indian cosmologies: Early models depicted the universe as a flat disc or layered spheres.
  • Geocentric Model: Proposed by Claudius Ptolemy (~150 CE), Earth at the center.
  • Heliocentric Model: Nicolaus Copernicus (1543), Sun at the center.

Modern Era

  • Isaac Newton (1687): Universal gravitation, infinite static universe.
  • Albert Einstein (1917): General relativity, introduced cosmological constant for a static universe.
  • Edwin Hubble (1929): Discovered universe expansion via redshift observations.

3. Key Experiments & Observations

3.1. Cosmic Microwave Background (CMB)

  • Discovery: Arno Penzias & Robert Wilson (1965), detected faint microwave radiation, evidence of the Big Bang.
  • Experiments: COBE (1989), WMAP (2001), Planck (2009-2013) satellites mapped CMB fluctuations.

3.2. Redshift Surveys

  • Hubbleā€™s Law: Galaxies move away from us; speed proportional to distance.
  • Sloan Digital Sky Survey (SDSS): Mapped millions of galaxies, revealing large-scale structure.

3.3. Gravitational Lensing

  • Einsteinā€™s Prediction: Massive objects bend light.
  • Observations: Used to map dark matter distribution.

3.4. Type Ia Supernovae

  • Standard Candles: Measure cosmic distances.
  • 1998 Discovery: Accelerating universe, led to concept of dark energy.

4. Modern Applications

4.1. Dark Matter & Dark Energy

  • Dark Matter: Invisible mass, inferred from galaxy rotation curves and lensing.
  • Dark Energy: Drives accelerated expansion, constitutes ~68% of universeā€™s energy.

4.2. Large-Scale Structure

  • Galaxy Clusters & Voids: Mapping cosmic web aids understanding of formation and evolution.

4.3. Cosmological Simulations

  • Numerical Models: Simulate universe evolution, test theories against observations.

4.4. Astrobiology & Extreme Life

  • Bacteria in Extreme Environments: Discovery of life in deep-sea vents and radioactive waste expands the search for extraterrestrial life.

5. Recent Breakthroughs

5.1. James Webb Space Telescope (JWST)

  • Launched: December 2021.
  • Findings: Observed earliest galaxies, challenged models of galaxy formation.

5.2. Fast Radio Bursts (FRBs)

  • Mysterious Signals: Detected from distant galaxies, origin still under investigation.

5.3. Mapping Dark Matter

  • 2023 Study: DESI (Dark Energy Spectroscopic Instrument) mapped millions of galaxies, refined measurements of dark energy (Nature, 2023).

5.4. Microbial Survival in Space

  • 2020 Study: Deinococcus bacteria survived 3 years on ISS exterior (Frontiers in Microbiology, 2020).

6. Data Table: Key Cosmological Parameters

Parameter Value (Latest) Source/Experiment
Hubble Constant (Hā‚€) 67.4 Ā± 0.5 km/s/Mpc Planck (2018)
Age of Universe 13.8 billion years Planck (2018)
Dark Energy Fraction ~68% Planck, DESI (2023)
Dark Matter Fraction ~27% Planck, SDSS
Baryonic Matter Fraction ~5% Planck
CMB Temperature 2.725 K COBE, Planck
Observable Universe Size ~93 billion light-years Planck, SDSS

7. Common Misconceptions

  • The Big Bang was an explosion in space: It was an expansion of space itself.
  • The universe has a center: Expansion occurs everywhere; no central point.
  • Dark matter is just regular matter we canā€™t see: It is a fundamentally different, non-interacting type.
  • Cosmology proves the universeā€™s fate: Models predict scenarios, but future observations may alter predictions.
  • All bacteria need mild conditions: Many thrive in extreme environments, such as deep-sea vents, Antarctic ice, and radioactive waste.

8. Recent Research Citation

  • DESI Collaboration (2023): ā€œThe Dark Energy Spectroscopic Instrument: Mapping the Universeā€™s Expansion,ā€ Nature, 2023.
  • Frontiers in Microbiology (2020): ā€œDeinococcus radiodurans Survival on the International Space Station,ā€ Frontiers in Microbiology, 2020.

9. Summary

Cosmology explores the universeā€™s origins, structure, and fate through observation, theory, and experimentation. Key discoveries include the expanding universe, cosmic microwave background, and the roles of dark matter and dark energy. Modern experiments like JWST and DESI continue to refine our understanding, while the survival of bacteria in extreme environments expands the potential for life beyond Earth. Common misconceptions persist, but ongoing research and technological advances drive cosmology forward, revealing new insights into the universeā€™s deepest mysteries.