Imagine you could go back 13.8 billion years to the dawn of time. What do you think you would hear during the Big Bang? We may not have time machines yet, but physicist John G. Cramer offers the next best thing. Here's his sonic simulation, which compresses 760,000 years of the early universe into about a minute and a half:
It's probably not the "bang" you expected. In fact, if you had actually been there, you would have heard nothing at all -- the frequencies were too low to have been heard by the human ear, and had to be boosted in this recording to be audible.
Why does the sound get deeper over the course of the recording? It's evidence of the Doppler shift, the same effect that distorts the sound of a passing siren.
"To put it another way," Dr. Cramer says on his website, "the expanding universe 'stretches' the sound wavelengths" and thereby lowers their pitch.
To create the simulation, Dr. Cramer used data collected by the European Space Agency's Planck spacecraft. The Planck mission recorded 15.5 months of ancient radiation released during and shortly after the Big Bang -- called the cosmic microwave background -- and Cramer used its temperature data to simulate how the cosmic event might have sounded.
It's pretty cool, but is there any practical application? Dr. Cramer thinks so.
"This 'sound fingerprint' allows us to learn a lot about the universe," he told the Huffington Post in an email, "including its age, its rate of expansion, and the fractions of its mass-energy represented by normal matter, 'dark matter' (about which we know very little), and 'dark energy' (about which we know even less)."