Universe Began 13.8 Billion Years Ago in Rapid Expansion, Not Explosion

Q: With dark energy accelerating our universe's growth, what invisible power makes up 70 percent of reality that scientists still cannot identify?

That invisible power is called dark energy. It is the name scientists give to whatever is causing the universe’s expansion to speed up, and current cosmology says it accounts for about 70% of the universe’s total matter-energy content. What dark energy actually is remains unknown. The simplest leading explanation is Einstein’s cosmological constant: a constant energy of empty space that exerts negative pressure, pushing space to expand faster over time. But researchers are still testing whether dark energy is truly constant or whether it changes over cosmic history. The evidence for it comes from several independent observations. In the late 1990s, astronomers studying Type Ia supernovae found that distant supernovae were dimmer than expected, showing the universe was not just expanding but accelerating. That result was later reinforced by measurements of the cosmic microwave background and baryon acoustic oscillations, which together fit the standard cosmological model very well. Recent challenges to dark energy have not overturned that picture. A 2026 reanalysis led by the University of Southampton found that claims the acceleration was an illusion came from errors in handling supernova and host-galaxy data. The broader evidence still supports an accelerating universe. So the “invisible power” is dark energy, but the honest scientific answer is that it is still a placeholder term for a real effect we observe much more clearly than we understand.

3 articles · Updated · Yahoo! Voices · Aug 15

Astronomers date the universe’s start to 13.8 billion years ago, describing the Big Bang as a rapid expansion that created space and time rather than a destructive blast.
Distant galaxies moving apart and the cosmic microwave background support that picture, showing the universe began extremely small and has kept expanding ever since.
That expansion is now speeding up, a trend scientists link to dark energy even though they still know little about what it is.
Researchers also say the universe is not expanding into anything, because space itself began with the Big Bang, and they still do not know what caused it.