Lecture - Professor Bob Lambourne - Contentious Cosmology

Cosmology is, the study of the universe as a whole - including its origin and evolution. It has been a major growth point in science for several decades. Its successes have been noteable, from Hubble's discovery of the recession of distant galaxies to the detection of Cosmic Microwave Background Radiation (CMBR) and the recognition of dark matter and dark energy. For the past thirty years there has been little doubt that the universe is in a state of expansion, initiated by a "Big Bang" that happened about 13 billion years ago. There have been disagreements about details; did the first galaxies appear before or after the first stars, what precisely is the current rate of recession of the universe, was the expansion faster or slower in the past, and what about the future - will it be endless expansion or a big crunch? Despite many challenges there has been broad agreement about the key facts, so astronomers and cosmologists have worked together to develop an agreed "Standard Model" in which increasingly precise answers have been provided for even the most challenging of questions. But all this may now be changing. In recent years the tension between astronomy and cosmology has started to increase. Precise measurements of the expanding universe, based on astronomical studies of supernovae and variable stars, are stubbornly refusing to come into line with expansion determinations based on cosmic background radiation. The ages of the most distant galaxies may now be too great to be accommodated within our relatively young universe, and the observed abundance of light elements, such as helium and lithium, may not be consistent with the "pressure cooker" of the Bg Bang. Are these 'tensions' real? Will they persist as new telescopes and new space probes provide even more precise data over the next few years? If so, something will have to give - but what? Will a few detailed tweaks save the Standard Model or is now the time for a fundamental reconsideration of our currently contentious cosmology?