3 days ago · The most widely accepted explanation for the origin of the universe is the big-bang theory, which proposes that the universe began approximately 13.8 billion years ago in an extremely hot, …

Discoveries in the early 20th century lead to the Big Bang theory with a hot fireball, cooling and becoming less dense as the universe expanded, allowing the first subatomic particles and simple …

Jul 17, 2025 · For the first time, light streamed freely through the cosmos. The light released at that moment is the oldest cosmic event that we can measure. Scientists discovered this “cosmic …

Jul 26, 2025 · The story of how the universe began is the story of how everything came to be. It is not just the domain of physicists and philosophers, but a tale that pulses in the blood of every human …

Nov 18, 2025 · Together, NASA’s Astrophysics missions are helping humanity understand not only where we came from, but how the universe continues to evolve—revealing the grand narrative of …

The Big Bang was the moment 13.8 billion years ago when the universe began as a tiny, dense, fireball that exploded. Most astronomers use the Big Bang theory to explain how the universe began.

May 14, 2024 · Origin of the universe: This article explores various theories about how the universe got started and how it will end.

Oct 19, 2023 · Throughout history, countless myths and scientific theories have tried to explain the universe's origins. The most widely accepted explanation is the big bang theory. Learn about the …

Jan 18, 2017 · How did the universe begin—and what were its early days like? The most popular theory of our universe's origin centers on a cosmic cataclysm unmatched in all of history—the big bang.

In the first moments after the Big Bang, the universe was extremely hot and dense. As the universe cooled, conditions became just right to give rise to the building blocks of matter – the quarks and …