by Dr. Shadab Alam, TIFR Mumbai

Abstract:

The universe is not just expanding - it's accelerating! This surprising discovery revealed the presence of a mysterious cosmic component we call "dark energy." Like an invisible force pushing galaxies apart, dark energy makes up most of the universe's energy content, yet its true nature remains one of the biggest puzzles in modern physics.

How do we study something we can't directly see? The answer lies in the cosmic web - the intricate pattern formed by millions of galaxies across space. Using the Dark Energy Spectroscopic Instrument (DESI), we are creating the most detailed three-dimensional map of these galaxies ever made. This map serves as a cosmic laboratory, allowing us to measure how the universe grows and changes over time.

In this colloquium, I will take you on a journey through our expanding cosmos. We'll explore how galaxy surveys like DESI act as our cosmic rulers and compasses, helping us measure the influence of dark energy. By studying how galaxies cluster together on the largest scales, we can decode the fundamental properties of dark energy and better understand the fate of our universe. I will share the latest discoveries from this exciting frontier of cosmology, showing how observations of the visible universe are helping us understand its invisible driving force.