Dark Energy in the Universe and the Largest Telescope Ever

A nontechnical talk by Dr. Robert Kirshner, Jan 28, 2026.One hundred years ago, Edwin Hubble showed that the universe is expanding. In the 1990s, astronomers found that the expansion is not slowing down, as expected, but speeding up. This led to a Nobel Prize in Physics (for our speaker's students) and a consensus that we live in a universe that is made up of invisible dark matter, mysterious dark energy, and only a pinch of the atoms we, and everything we can see in the Universe, are made of. Dr. Kirshner explains this history in everyday language and reviews recent observations indicate that even this picture may be too simple to account for all the evidence. He also discusses the status of building the largest telescopes ever planned in Earth's Northern and Southern hemispheres. Robert Kirshner is Emeritus Professor of astronomy at Harvard and Research Professor at the California Institute of Technology. He was the Head of Science at the Gordon and Betty Moore Foundation, and now serves as the Executive Director of the Thirty-Meter Telescope International Observatory.