Is This What the Big Bang *Sounded* Like?

Is there any more primal curiosity than the desire to know how the Universe began? Cosmologists devote their lives to piecing that puzzle together, but the evidence they have to work with -- the remaining traces of those early hundreds of thousands of years (to say nothing of the early minutes or seconds) -- is scant: radiation know as cosmic microwave background (CMB) that permeate the universe. By mapping tiny variations in these waves, scientists can work backwards to describe the composition and structure of the early universe.

They can also imagine what that early time may have sounded like.

This is the side project of John G. Cramer, a professor emeritus at the University of Washington, Seattle. Cramer has taken the new, highly detailed data from the European Space Agency's Planck mission, which measures CMB, and run them through Mathematica software to convert the CMB measurements into an audio simulation of the universe's first 760,000 years (an extremely brief period on a cosmological scale). Here's what he got:

This is not to say this is what you would have heard had you been present in the years following the initial explosion (if through some weird wormhole magic that were even possible *and* you managed to live for the entire 760,000 years). Cramer calls the early universe a "bass instrument," because its expansion stretched out the sound wavelengths, making their frequencies lower and lower -- far too low for a human to hear. In order to make the simulation audible, he had to scale up the sound frequencies by an enormous factor: 10²⁶. As you listen, you can hear a distinct rise and fall of the CMB emissions' intensity, peaking at 379,000 years.

The simulation is part science, part art -- the conversion of data into something you can experience and explore. Those initial years of existence are obscured by the noise of the intervening 13+ billion years, and a sonic trip to hear them is a tool more for provoking the imagination than it is for representing any sort of early reality. But even if we have no real clear picture of that very first beginning, we should be grateful for the small evidence we do have -- these faint microwaves -- before they too disappear. As Ross Andersen wrote in Aeon, "In a trillion years' time [the CMB] is going to slip beyond what astronomers call the cosmic light horizon, the outer edge of the observable universe. The universe's expansion will have stretched its wavelength so wide that it will be undetectable to any observer, anywhere. Time will have erased its own beginning." So for now, let's explore them every which way we can -- including with our ears.