Like the mysterious grinning Cheshire Cat in Alice in Wonderland, only one aspect of the invisible ‘dark matter’ which dominates the universe is apparent: its gravitational effects. “We live in a universe that is completely dominated by invisible matter whose origin and nature are essentially unknown,” says Dr Allan Ernest, a physics lecturer with the School of Dentistry and Health Sciences at Charles Sturt University (CSU) in Wagga Wagga. In a lecture on Wednesday 28 April, Dr Ernest will examine the latest theories which attempt to answer the vexing questions: “What gravitational effects tell us dark matter exists? If it is really there, what could it possibly be? Are there alternative theories to dark matter?” The talk by Dr Ernest will also present work being conducted at CSU to address the questions surrounding the nature and origin of dark matter.