A Universe dominated by dark energy?

Abstract Observations of our Universe have led to a current consensus model which has a number of unexpected and, some would say bizarre characteristics. These include two epochs in time when it exhibits a ‘strange’ behaviour, namely the Big Bang moment of creation itself and the subsequent period of initial inflation. In addition the models now require two unseen and dominant constituents of the Universe to explain its dynamics, which are known as ‘dark matter’ and ‘dark energy’. Having said that, once these four features are included the model is very successful in explaining a vast range of astronomical observations, spanning virtually the whole lifetime of the Universe. This paper focusses on dark energy, starting from an historically much simpler model and then building up to the present day understanding with reference to the key observations which have driven changes in paradigm. Possible suggestions as to the nature of dark energy are considered and finally a section is included concerning how future observations may lead to a better understanding.