Dark energy represents one of the most profound mysteries in modern cosmology—a hypothetical form of energy that permeates all of space and drives the Universe's accelerating expansion. Comprising approximately 68% of the Universe's total energy density, dark energy exerts a repulsive gravitational effect that counteracts the attractive pull of matter and dark matter.</p><p>The discovery emerged from groundbreaking observations in 1998, when two independent teams studying distant Type Ia supernovae found that these "standard candle" explosions appeared dimmer than expected. This dimness indicated the supernovae were farther away than predicted, revealing that the Universe's expansion was accelerating rather than slowing down as previously assumed. This shocking revelation earned the 2011 Nobel Prize in Physics.</p><p>Dark energy's influence becomes dominant at vast scales. For example, it prevents galaxy clusters from growing larger through gravitational attraction and will ultimately determine the Universe's fate—potentially leading to a "Big Rip" scenario where space expands so rapidly that atoms themselves are torn apart.</p><p>Despite decades of research, dark energy's true nature remains enigmatic. Leading candidates include Einstein's cosmological constant (a property of space itself) or dynamic quantum fields. Current missions like the Dark Energy Survey and future space telescopes continue investigating this cosmic enigma that fundamentally shapes our Universe's destiny.
Examples
**Example:** Dark energy accounts for about 68% of the universe's total energy. Discovered in 1998 through observations of distant supernovae, it's causing the universe's expansion to accelerate rather than slow down.