The Hobby-Eberly Telescope Dark Energy Experiment

A scientific revolution is underway. It will tell us more about the universe than we have ever known before, because it will tell us what makes up almost three-quarters of all the matter and energy in the universe. It will tell us if the laws of gravity are correct, and reveal new details about the Big Bang in which the universe was born.

The subject of this revolution is dark energy, a mysterious force that is causing the universe to expand faster as it ages. And one of the leaders in the revolution is HETDEX — the Hobby-Eberly Telescope Dark Energy Experiment — at The University of Texas at Austin McDonald Observatory. HETDEX will be the first major experiment to probe dark energy. Its observations will narrow the list of possible explanations for dark energy, and may even provide the final answer.

HETDEX will combine the immense light-gathering power of the Hobby-Eberly Telescope, the world’s third largest, with an array of new instruments for analyzing the light from distant galaxies.

During three years of observations, HETDEX will collect data on at least one million galaxies that are 9 billion to 11 billion light-years away, yielding the largest map of the universe ever produced. The map will allow HETDEX astronomers to measure how fast the universe was expanding at different times in its history. Changes in the expansion rate will reveal the role of dark energy at different epochs. Various explanations for dark energy predict different changes in the expansion rate, so by providing exact measurements of the expansion, the HETDEX map will eliminate some of the competing ideas.

More information, as well as videos, podcasts, and high-resolution images related to this project are available at its dedicated website,

HET at Twilight