Dark energy may be the most mysterious substance ever proposed, but many scientists are certain it exists. Why?

The term “expanding universe” is often misunderstood, even by people familiar with astronomy. This explanation breaks down what actually expands and what does not, using modern cosmology rather than ...

The shape of the universe is not something we often think about.

The rapid acceleration of the universe’s expansion continues to challenge our understanding of fundamental physics. Why the universe is expanding faster and faster remains one of the most intriguing ...

The universe is expanding, and while that fact is fascinating, it also creates a question that trips people up: if it’s growing, what exactly is it expanding into? Our brains are used to picturing ...

An expanding universe complicates this picture just a little bit, because the universe absolutely refuses to be straightforward. Objects are still emitting light, and that light takes time to travel ...

The expansion of the universe may be slowing down rather than accelerating, according to a new study that challenges the Nobel Prize-winning theory of dark energy. “If confirmed, this would have ...

AUSTIN (KXAN) — A commonly held belief that the universe is rapidly expanding may be wrong. A new paper published this month suggests the universe’s expansion might be slowing down and it could mean ...