| Abstract |
Observations of the cosmic microwave background radiation by the European Space Agency’s Planck
satellite have led to a standard model of cosmology with very precisely determined parameters. In this
model, known as LCDM , structure in the Universe arose from quantum fluctuations that were stretched in
scale during an early inflationary phase in the Universe’s history. At the present day most of the matter is
cold and invisible, but most of the energy is in an unusual form that is also dark and invisible. I will first
discuss, from a personal perspective, how we got to the LCDM model. I will then ask whether we have
actually learned anything, given that the three key ingredients of the LCDM cosmology – inflation, cold
dark matter and dark energy – are not understood at a fundamental level. I will then speculate on whether
there is likely to be a new paradigm shift in cosmology within the next few years.
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