Project overview
Understanding what the universe is made of has motivated humankind for thousands of years. The quest to find the answer has inspired the creativity and work of generations of scientists, so it may be a surprise that the nature of over 90% of the Universe is a mystery to us. But we do know that the universe is getting bigger with time and, very unexpectedly, is doing so at an ever faster rate. This presents one of the most exciting challenges to modern science: the quest to understand this unexpected acceleration. The unknown substance responsible is called dark energy; as the name suggests we know little about it. We think that it makes up about 70% of the Universe with an incredibly low density -- much less than a speck of dust in a volume of space the size of the Earth. Beyond that, there are only theories. This project uses cosmic explosions known as supernovae, violent thermonuclear explosions from dying stars that can outshine entire galaxies. These supernovae explode with about the same brightness every time, and are what astronomers call standard candles. They can act as cosmic rulers that can measure vast intergalactic distances, and help us understand how the universe has changed in size over its lifetime. This project makes use of two new astronomical mega facilities in which the UK has invested: The Vera C. Rubin Observatory and the 4MOST Telescope. Rubin surveys the night sky every three nights and can hunt out supernovae billions of light-years away, measuring their brightness as they appear to us on Earth. The 4MOST telescope measures their spectroscopic information, to measure the redshift of the supernovae and their chemical compositions. We will use these supernovae to conduct a defining measurement of the dark energy that makes up most of the universe, and investigate the physics of the standard candles that we take for granted. Though this project has limited practical application, there are fewer more fundamental questions about Nature that remain to be answered than the question of dark energy. Understanding the Universe we live in has challenged us ever since early humans became fascinated by the environment around them. Research such as this continues our exploration and understanding of the Universe that surrounds and intrigues us.
