Scientists Say: Big Bang

This is the current theory about how our universe began

This image shows how the universe might have come to be, from a small dense point at left, through “quantum fluctuations” and then to the Big Bang. That time of rapid inflation left behind the light pattern that scientists see today — called cosmic background radiation. After a period called the “dark ages,” matter condensed and cooled, and stars and planets began to form. 

WMAP Science Team/NASA

Big Bang (noun, “Big Bang”)

This theory explains how our universe began. About 14 billion years ago, all the matter — and energy — that makes up the universe was squashed into an incredibly small point. Because the matter was so condensed, it wasn’t in any form we would recognize today. There were no atoms or even particles. Suddenly, though, it all went through a rapid expansion — an explosion, in a way. That’s the Big Bang. The result was a super-hot, super-dense “cosmic soup” of matter and energy. Over tiny fractions of time, light and charged particles such as protons emerged. Only a few minutes after the Big Bang, the element hydrogen formed. Later, over millions of years, matter began to clump into what would become stars and planets. The universe kept on cooling and expanding, and forming more complex structures, such as galaxies. And it continues to do so today. 


In a sentence

The best evidence for the Big Bang is the remnants of the light — called cosmic background radiation — released from the original explosion.

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Bethany Brookshire was a longtime staff writer at Science News Explores. She has a Ph.D. in physiology and pharmacology and likes to write about neuroscience, biology, climate and more. She thinks Porgs are an invasive species.

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