The Big Bang occurred nearly 14 billion years ago, long before anyone was around to witness it. So how would we know what, if any, sound it made?

By Lola Gayle, Editor-at-large

This one’s from The Vault, but worth dusting off for the sake of those who may have missed it the first time around.

The Big Bang occurred nearly 14 billion years ago, long before anyone was around to witness it. So how would we know what, if any, sound it made? One researcher has spent over a decade trying to find out, resulting in several eerie recordings that he has since-remastered.

Experts have long believed that colossal sound waves were spawned by the expansion of the early Universe. This would have sent echoes throughout the dense plasma/hydrogen medium of the early Universe some 100 to 700 thousand years after the initial Big Bang.

In 2001, University of Washington physicist John Cramer wrote an article for Analog Science Fiction & Fact magazine that described what the Big Bang may have sounded like.

Several years later, the mother of an 11-year-old boy working on a science project for his class read the article and asked Cramer if the sound of the Big Bang had actually been recorded. Of course his answer was “no,” but her question caused him to consider the problem in more detail.

Cramer took data from a BOOMERanG balloon experiment and data from NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) and plugged it all into Mathematica, a symbolic algebra program. That work culminated in the creation of a 100-second recording (download WAV file) which represents the sound from roughly 380,000 years after the start of the Big Bang until about 760,000 years after, when it was just 18 million light years across.

Because the 2003 data lacked high frequency structure, in 2013 Cramer decided to re-master his recording using new data from the European Space Agency’s Planck satellite mission, which has detectors so sensitive that they can distinguish temperature variations of a few millionths of a degree in the cosmic microwave background.

As the universe cooled and expanded, it stretched the wavelengths to create “more of a bass instrument,” Cramer said in a statement at the time. The sound gets lower as the wavelengths are stretched farther, and at first it gets louder but then gradually fades. The sound was, in fact, so “bass” that he had to boost the frequency 100 septillion times (that’s a 100 followed by 24 more zeroes) just to get the recordings into a range where they can be heard by humans.

The effect is similar to what seismologists describe as a magnitude 9 earthquake causing the entire planet to actually ring. In this case, however, the ringing covered the entire universe -– before it grew to such gargantuan proportions.

“Space-time itself is ringing when the universe is sufficiently small,” Cramer said.

Click here to listen to the re-mastered version at varying lengths.

big bang sound 2
Timeline of the metric expansion of space, where space (including hypothetical non-observable portions of the universe) is represented at each time by the circular sections. On the left the dramatic expansion occurs in the inflationary epoch, and at the center the expansion accelerates (artist’s concept; not to scale). NASA
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