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The relativistic Universe

If you are interested in using quantitative physical methods to understand relativistic and high-energy processes in the Universe, and already have a good background in OU level 2 maths, physics and astronomy, then this is the module for you. This module comprises three parts that present, in turn, the theoretical basis for modern cosmology, described by Einstein’s special and general theories of relativity; cosmological observations of the local and distant Universe that are used to understand its structure and evolution; and high-energy phenomena in the Universe including interacting binary stars, active galactic nuclei and gamma-ray bursts.

What you will study

This module will give you a good understanding of relativistic astrophysics and cosmology, including both their theoretical underpinnings and their observational consequences. It is a mathematical module that builds on skills and concepts you will have developed by studying maths, physics and astronomy at a level equivalent to OU level 2 modules. The module makes full use of tools in the OU’s Virtual Learning Environment (VLE) and internet-based resources are used throughout.

Part 1, Relativity, Gravitation and Cosmology, is based around a book which allows you to develop an understanding of special and general relativity and apply this knowledge to the structure and evolution of the Universe as a whole. You will learn how a metric is used to describe mathematically a space-time (including unrealistic two- and three-dimensional models, as well as possibly more realistic four-dimensional space-times). You will then develop an understanding of Einstein’s theory of general relativity as a metric theory of gravity, including the role of the Einstein field equations, some examples of specific solutions and the current status of a range of ‘tests’ of general relativity. Finally you will learn about the existence, nature and implications of cosmological solutions to the Einstein field equations subject to the assumption of large-scale homogeneity and isotropy (including the effect of a cosmological constant/uniform dark energy density).

Part 2, Observational Cosmology, is based around a book which allows you to learn about the various observational techniques and measurements that provide a picture of the structure and evolution of the Universe on the largest scales. You will acquire knowledge and understanding of statistical cosmological techniques as well as current relativistic cosmological models and the observational evidence for them. You will learn about the bulk properties of local and distant galaxies and the physical inferences that can be made from them.

Part 3, Extreme Environment Astrophysics, is based around a book which focuses on the role of accretion in the presence of strong gravitational fields and the physics of relativistic objects, including white dwarfs, neutron stars and black holes. You will learn the physics of the main high-energy phenomena arising in compact and accreting systems as well as the main physical processes occurring in, and parameters of, accreting systems at small and large scales. You will study the astrophysics of interacting binary stars, active galaxies, accretion discs, their outbursts and outflows, and gamma-ray bursts, and will also discover the methods used in the measurement and characterisation of accretion flow properties. Your study of this part will allow you to develop basic concepts of hydrodynamics, thermodynamics and plasma physics.

Entry requirements

The relativistic Universe (S383) is an OU level 3 module. It builds on study skills and subject knowledge acquired at OU levels 1 and 2.

We’ve designed S383 to follow these four modules:

These parts are especially significant:
  • ‘Galaxies and cosmology’ in S284
  • ‘Ordinary and partial differential equations’ and ‘Matrices’ in MST224.

Check you’re ready for S383.

Talk to an advisor if you’re not sure you’re ready.

Preparatory work

As a result of taking the Are you ready for ...? test, you may find that you need to study a further module or modules before embarking on S383. If this is not possible, you may choose to spend time studying relevant background material. For this purpose we have produced a ‘Book 0’ for S383 (and the related module S382) entitled An introduction to astrophysics and cosmology, which you may download as a PDF. This document covers the recommended background knowledge and skills that we expect students to possess before embarking on S383. If you need to study all the maths, physics and astronomy background contained within this Book 0, we estimate it will require about 40–60 hours of study. It is not a replacement for taking the appropriate OU level 2 modules, but it will serve to fill the gaps in your knowledge in many cases.

What's included

You'll have access to a module website, which includes:

  • a week-by-week study planner
  • course-specific module materials
  • audio and video content
  • assignment details and submission section
  • online tutorial access.

You'll also be provided with three printed module books and a DVD-ROM.

You will need

Basic scientific calculator.

Computing requirements

You’ll need broadband internet access and a desktop or laptop computer with an up-to-date version of Windows (10 or 11). Any macOS is unsuitable with this module.

Any additional software will be provided or is generally freely available.

To join in spoken conversations in tutorials, we recommend a wired headset (headphones/earphones with a built-in microphone).

Our module websites comply with web standards and any modern browser is suitable for most activities.

Our OU Study mobile app will operate on all current, supported versions of Android and iOS. It’s not available on Kindle.

It’s also possible to access some module materials on a mobile phone, tablet device or Chromebook. However, as you may be asked to install additional software or use certain applications, you’ll also require a desktop or laptop as described above.

Teaching and assessment

Support from your tutor

Throughout your module studies, you’ll get help and support from your assigned module tutor. They’ll help you by:

  • Marking your assignments (TMAs) and providing detailed feedback for you to improve.
  • Guiding you to additional learning resources.
  • Providing individual guidance, whether that’s for general study skills or specific module content.
  • Facilitating online discussions between your fellow students, in the dedicated module and tutor group forums.

Module tutors also run online tutorials throughout the module. Where possible, recordings of online tutorials will be made available to students. While these tutorials won’t be compulsory for you to complete the module, you’re strongly encouraged to take part.


The assessment details for this module can be found in the facts box above.

You will be expected to submit your tutor-marked assignments (TMAs) online through the eTMA system unless there are some difficulties which prevent you from doing so. In these circumstances, you must negotiate with your tutor to get their agreement to submit your assignment on paper.

You will, however, be granted the option of submitting on paper if typesetting electronically or merging scanned images of your answers to produce an electronic TMA would take you an unacceptably long time.

There will be a mixture of online interactive computer-marked assignments (iCMAs) and short tutor-marked assignments (TMAs), with a total workload equivalent of three full TMAs.

Both the iCMAs and TMAs will focus strongly on learning through practice rather than on assessment. The feedback you receive on your answers will help you to improve your knowledge and understanding of the study material and to develop important skills associated with the module. The feedback on the iCMAs will be instantaneous and hints will be given so that you can refine any incorrect answers. Although your scores on all these assignments will not contribute directly to your module grade, they form an essential part of the learning process and you will be required to submit a proportion of them to complete the module.

Your overall module grade will be based on two examinable components. The first comprises an extended written assignment for Part 2 of the module which you submit at the end of this study period. The other is an end-of-module written examination based on Parts 1 and 3.

If you have a disability

The OU strives to make all aspects of study accessible to everyone and this Accessibility Statement outlines what studying S383 involves. You should use this information to inform your study preparations and any discussions with us about how we can meet your needs.

Future availability

The relativistic Universe (S383) starts once a year – in October.

This page describes the module that will start in October 2022.

It will start for the last time in October 2022. We plan to replace The relativistic Universe (S383) with a new module – Cosmology and the distant Universe (S385) – that will start for the first time in October 2023.

Course work includes:

4 Tutor-marked assignments (TMAs)
4 Interactive computer-marked assignments (iCMAs)
No residential school