Our Universe: what we think we know

In this course we tell the story of our Universe from when it was a millionth of a second old until the present day and consider how it might end.  

To do this we use light, which thanks to its finite speed, allows us to look back in time as we look deep in space, to the moment when the Universe was about 1/20 its present age. In the last few years our understanding of the Universe has been extended by the detection of gravity waves. We will follow the emergence of hydrogen and helium a few minutes after the Big Bang, through the first generation of stars, which may have been 1000 times the mass of the Sun, up to the present day. The story of the birth and death of stars is the story of the battle of matter against gravity, a battle that gravity always wins, with either a whimper or a bang. It is also the story of the origin of all the elements that make up everything we see around us, including ourselves.  

Low mass stars like the Sun enrich the Universe with lighter elements like carbon nitrogen and oxygen, while more massive stars end their lives in giant supernova explosions producing heavier elements such as iron and leaving behind sometimes nothing, sometimes neutron stars or black holes.  

Most stars are in double systems and when these evolve they can exchange matter and leave a variety of remnants including pairs of black holes or neutron stars or combinations of both. These eventually merge and in the case of neutron stars, this results in a pulse of gravitational waves and the production of the heaviest elements such as gold.  

Stars make up galaxies, which at their centres contain thousand million Solar mass black holes that govern their evolution. Galaxies form clusters, that are immersed in giant haloes of gas so hot they emit X-rays, as well as halos of mysterious dark matter, which outweighs all other matter. On the very largest scale, the evolution of the Universe is dominated by the even stranger vacuum energy, about which we know even less. Finally, we will consider if we are the only self-aware beings in our Universe and if so why this may be. 

Learning outcomes

The learning outcomes for this course are:

• To have a deeper understanding of the world around us  
• To better understand media reports of new astronomical discoveries  
• To have a broader perspective of our own significance and possible future, within in the context of the Universe  

Classes

1 The Scale and Contents of the Universe
We will look at the hierarchy of structures from star clusters to galaxies and clusters of galaxies. As we look at the Universe on ever greater scales and see the influence of dark matter and vacuum energy in shaping the past and future of the Universe. Visible light does not reveal all the matter in the Universe, which is only seen if we extend our use of the electromagnetic spectrum to the X-ray and infrared, revealing the hottest and coldest material in the Universe  

2. The Birth and Death of stars and Origin of the elements 1
We will see how hydrogen and helium were formed within the first few minutes after the formation of our Universe.  The force of gravity then counters the expansion of the Universe forming the first stars. These were massive and evolved more rapidly than future generations of stars, enriching the Universe with the first heavy elements.  After 9 thousand million years our Sun was born. We will then look in more detail at the evolution of solar mass stars and how they end their lives.  

3. The Birth and death of stars and Origin of the elements 2
In the second lecture we will see how stars more than five to eight times the mass of the Sun explode as super novae, creating more heavy elements. We will then look at the most massive stars and how they create black holes or neutron stars and be responsible for the bursts of gamma rays seen at random across the sky. Many stars form in close pairs and as they evolve they can exchange matter, causing them to evolve in quite a different ways including producing pairs of neutron stars that eventually merge creating the heaviest elements, including gold. We will end by showing how the material we see around us has been cycled through several generations of stars.

4. Solar Systems; Ours and Others
After considering the origin of our solar system we will take a tour of through it’s wide variety of  environments, ranging from the dry cold deserts of Mars, the lead melting environment of Venus and the icy wastes of Pluto. We will then see how our Solar System compares with the many solar systems we are currently finding around other stars.  

5. Are we Alone?          
In previous lectures, we have seen that we live in a Universe perfectly suited to our existence. On Earth, life is found in rocks, ice and boiling water, suggesting it would be impossible to destroy, before the Sun becomes a red giant. Yet space is silent, suggesting, that though simple life may be common, technologically advanced life might be very rare. We will present the evidence, then take a closer look at the development of life on Earth. We will consider how to detect life and in particular intelligent life elsewhere in the Universe and use the Frank equation to predict the probability that there is intelligent life elsewhere and if not why this might be.  

Typical week: Monday to Friday

For each week of study you select a morning (Am) and an afternoon (Pm) course, each course has five sessions, one each day Monday to Friday. The maximum class size is 25 students. Your weekly courses are complemented by a series of two daily plenary lectures, exploring new ideas in a wide range of disciplines. To add to the learning experience, we are also planning additional evening talks and events.

Evaluation and Academic Credit 

If you are seeking to enhance your own study experience, or earn academic credit from your Cambridge Summer Programme studies at your home institution, you can submit written work for assessment for one or more of your courses. 

Essay questions are set and assessed against the University of Cambridge standard by your Course Director, a list of essay questions can be found in the Course Materials. Essays are submitted two weeks after the end of each course, so those studying for multiple weeks need to plan their time accordingly. There is an evaluation fee of £65 per essay.

For more information about writing essays see Evaluation and Academic Credit.

Certificate of attendance

A certificate of attendance will be sent to you electronically within a week of your courses finishing.