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PX389 Cosmology

Lecturer: Grant Kennedy
Weighting: 7.5 CATS

Questions about the origin of the Universe, where it is going and how it may get there are the domain of cosmology. One of the questions addressed in the module is whether the Universe will continue to expand or ultimately contract. Relevant experimental data include those on the Cosmic Microwave Background radiation, the distribution of galaxies and the distribution of mass in the Universe. The module discusses the implications of these in some detail. Starting from fundamental observations such as that the night sky is dark and, by appealing to principles from Einstein's General Theory of Relativity, the module develops a description of the Universe. This leads to the Friedmann equation, Hubble's law, the cosmological redshift and eventually to the Big Bang Model, with singular behaviour at the origin of the Universe. The module also discusses the evolution of the primeval fireball, the synthesis of Helium and the origin of structure.

To present the credentials of the Universe as we know it (via experiment) and introduce the simplest models which can describe it. The module should stress the role of experimental data and emphasize the need to distinguish between cosmology as a physical science, which makes testable predictions, and untestable pseudo-cosmologies which may claim to give appealing and all-encompassing accounts of the universe but are untestable.

By the end of the module, you should:

  • have a good qualitative appreciation of the current status of cosmology
  • recognise the importance of observations in constraining possible cosmological theories
  • understand the evolution of model universes, and how this evolution depends on their energy density components
  • be aware of some of the aspects of cosmology where more work is needed to reconcile theory and observations


  1. The history and foundations of modern cosmology: Olber’s Paradox, Hubble’s Law and the Cosmological Principle.
  2. Describing the evolution of the Universe: basics of space time and relativity, curvature, Friedmann equation, fluid and acceleration equations.
  3. Model universes: describing the evolution when dominated by single component and multiple-components - the standard cosmological (benchmark) model.
  4. Key properties of our Universe: tests of the standard cosmological model, evidence for dark matter; models for dark matter, origin of structure.
  5. The early Universe: the Big Bang, connection to elementary particle physics and grand-unified field theories (GUTS), inflation, Big Bang nucleosynthesis, formation of the cosmic background radiation.

Commitment: 15 Lectures

Assessment: 1.5 hour examination.

This module has a home page.

Recommended Texts: Please see homepage

Leads to: PX436 General Relativity