Dark Energy - NASA Goddard

Roman will help illuminate the dark energy puzzle by using multiple methods to explore how the universe has evolved throughout cosmic history.

The universe is ballooning outward as space itself stretches, perhaps under the force of a mysterious cosmic pressure known as dark energy. 

Galaxies like our own are hurtling away from each other at an ever-increasing clip, swept apart by an unseen power. All the stars in our galaxy, the particles in our planet, and even the atoms in our bodies would immediately fly apart if they weren't held together by stronger forces. 

Though weak on small scales, dark energy dominates across vast stretches of the cosmos. It makes up about 68% of the universe's total contents, but so far we don't know much more about it. In some ways, the mystery has gotten even more confusing as we've learned more — the latest and most thorough observations seem to show that the strange pressure is shifting over time, holding the fate of the universe in the balance. NASA’s Nancy Grace Roman Space Telescope will usher in a new era of dark energy exploration, potentially solving the mystery of its true nature.  

Until the 20th century, most scientists believed the universe was static, remaining essentially unchanged throughout eternity. Gradually, astronomers discovered that not only is our universe expanding — its expansion is inexplicably speeding up, possibly due to a mysterious forced dubbed dark energy. The next wave of dark energy missions, including NASA's Nancy Grace Roman Space Telescope, will search for clues by mapping galaxies and watching how they move, grow, and bend light to track expansion more precisely over longer stretches of cosmic time.

NASA's Goddard Space Flight Center

Illuminating Dark Energy

To figure out whether dark energy truly exists (and, if so, what it actually is), scientists are studying how it behaves. But it seems the more we learn about the mystery, the more perplexing it becomes. Recent results hint that dark energy may be changing over time in ways we don't yet understand. 

The next wave of dark energy missions will search for clues by mapping galaxies and watching how they move, grow, and bend light to track expansion more precisely over longer stretches of cosmic time. 

Together, Roman, Rubin, and Euclid will usher in a new era of dark energy discovery 

When Roman opens its eyes to the cosmos, its large field of view and crisp infrared vision will help scientists collect a treasure trove of valuable data. The mission will use several different measurement techniques to test our model of the universe between early and modern periods, with each method cross-checking the others.  

The recent discovery that dark energy may be evolving could mean that dark energy began influencing the universe’s expansion earlier than scientists thought. Roman will explore cosmic expansion during earlier epochs, providing unique information that remains shrouded from other telescopes. 

This could confirm whether dark energy is really changing over time and offer clues to explain such unexpected behavior.  

Source: Dark Energy - NASA Science