The Sound of the Big Bang
If a universe explodes into existence, and no one is around to hear it, does it still make a sound? The answer, according to physicist John Cramer, is a resounding yes.
“The early universe was like a hypersphere of space that was resonating with frequencies rollicking around in it,” said Cramer, a University of Washington physics professor who also conducts research at Brookhaven’s Relativistic Heavy Ion Collider (RHIC). He used temperature fluctuation maps of the early universe to create a recording of the Big Bang as it might have sounded 14 billion years ago.
“There’s that saying from the Alien movie franchise: In space, nobody can hear you scream. The logic is that it’s a vacuum and sound waves can’t propagate, but in the early universe, someone could hear you scream. The medium was a lot more dense than even the atmosphere of today’s Earth,” Cramer said.
“The special thing about the early universe is that because it was so small, sound waves could propagate and come back around on themselves. As it opened up, as the universe expanded, the sound got Doppler-shifted to higher and higher frequencies,” he said.
The Big Bang was a bass singer to rival all others. The frequencies of the volatile birth of the universe were so low, they were out of range of human hearing. Just to get the recording to a frequency humans can hear, Cramer had to increase the frequency of the universe’s big debut by 100 septillion times.
So, yes, the Big Bang made a sound, but even if we were around to hear it, we couldn’t have done so without the help of modern technology.