The universe is flying apart faster and faster every second

Space · Published 22 October 2026 Swipe more like this →

In short: For decades, scientists assumed gravity would eventually slow down the expansion of our universe. They were wrong. Since about five billion years ago, an invisible force has been pushing galaxies apart at an accelerating rate, making up roughly 70% of everything in existence.

The discovery of dark energy fundamentally shifted our understanding of the cosmos. While the universe began with a rapid expansion during the Big Bang, gravity was expected to act as a cosmic brake, pulling matter together over billions of years. However, in the late 1990s, observations of distant supernovae revealed a shocking reality: galaxies are not just receding; they are accelerating away from one another. This led astrophysicist Michael Turner to coin the term 'dark energy' in 1998 to describe the unknown force driving this expansion.

Because dark energy has never been directly seen or measured, it remains a 'catchall' term for a mystery. Scientists have proposed several competing theories to explain its behavior. The 'cosmological constant' represents a primary idea, proposing that cosmic acceleration stems from the energy inherent in empty space. Alternatively, 'quintessence' describes a changing field that functions as a force of 'anti-gravity'. More radical theories suggest that our current understanding of gravity might be fundamentally flawed, or that dark energy involves hypothetical particles like tachyons that travel faster than light.

Despite the lack of a definitive answer, we know dark energy possesses specific properties: it must be a substance or fluid that overcomes gravity's attractive nature and is spread uniformly across all of space-time. It currently dominates the universe's energy budget, accounting for approximately 68% to 70% of all matter and energy. Until we can identify its true nature, we remain unable to sensibly speculate on the ultimate destiny of the universe.

The path to this discovery relied on foundational work from the early 20th century. In 1912, Henrietta Swan Leavitt established a relationship between the brightness and periods of Cepheid variables, allowing astronomers to measure vast distances. This, combined with Vesto Slipher's early observations of 'redshift'—the stretching of light waves as objects move away—provided the essential tools for modern cosmology to eventually identify this accelerating trend.

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