The expansion of the universe was discovered by separate theoretical and observational work in the 1920s. Since then, the expansion has become a core aspect of the astrophysical field of …

expanding universe, dynamic state of the extragalactic realm, the discovery of which transformed 20th-century cosmology.

Nov 10, 2025 · Now, a new study might upend that idea, suggesting the universe’s expansion is actually slowing down—and that dark energy is diminishing, rather than stable. These findings …

Nov 20, 2025 · A new study casts doubt on the universe’s accelerating expansion, suggesting dark energy might be weakening over time.

Nov 23, 2025 · Expansion operates on scales where speed-of-light limitations cease applying, permitting universe to expand faster than light at cosmic distances. This apparent paradox …

Aug 18, 2025 · By the end of the twentieth century, astronomers uncovered a revelation so unexpected that it shook the foundations of cosmology: the expansion of the universe is not …

Mar 11, 2024 · The puzzle, called the "Hubble Tension," is that the current rate of the expansion of the universe is faster than what astronomers expect it to be, based on the universe's initial …

Dec 18, 2024 · Initiated by the Big Bang, this expansion is accelerating due to dark energy, which comprises most of the universe’s total energy. The complexities of expansion challenge both …

Dec 9, 2024 · New observations from the James Webb Space Telescope suggest that a new feature in the universe -- not a flaw in telescope measurements -- may be behind the decade …

Dec 13, 2024 · Then, in 1998, scientists discovered the universe’s rate of expansion is accelerating. In the years since, researchers using the Hubble Space Telescope have …