Example Sound
How Can We Know This?


The next few pages take us on a remarkable journey, far into space and far back in time – to an era when everything was different: there were no stars or galaxies, no planets or people, not even atoms were yet fully formed. At that time, the newborn Universe was pristine and formless – a brilliant expanding fireball of light and matter.

And yet within that sea of brilliance, the seeds for all that we now know were already present, latent, waiting to unfold. Most remarkable of all, perhaps, these seeds were sounds – pressure waves coursing through the fluid. A symphony of sorts, though not one that we would recognize as music. This symphony had three movements, each with its own form and character. The final movement built to a unique crescendo, unlike any other before or since: its final cacophonous chord dissolved to become the first generation of stars, whose light brought to a close the Universe's first cold dark night with a new dawn.

Even more remarkable: this story isn't fiction, or even myth; it is history.

Last sound first

Since this isn't a crime novel, let's skip to the final chapter and listen to one version of the cosmic sound: in this case the first million years, compressed to 10 seconds, shifted up by 50 octaves, and played at constant volume:

Click for sound

Not too musical, I know, but three movements nevertheless: a descending scream; a deep roar; and a final growing hiss, which ultimately spawns the first generation of stars.

How Can We Possibly Know This?

The extraordinary truth is that we can see the sound waves, exactly as they were, just 400,000 years after the Big Bang. We see them imprinted on a glowing foggy wall – caught, frozen in motion as they crossed the wall.

Because of cosmic expansion, we see the glowing wall not in its original brilliant orange light, but in faint microwaves. This is the famous Cosmic Microwave Background. It is our window on the infant Universe, and is one of nature's most generous and revealing gifts.

Our story, then, is set in ancient times – the era of sound sits firmly in creation's first million years. Let's start by getting a feel for the conditions of that remote time without, initially, any justification. Once the stage is set we can then introduce our main character, the cosmic microwave background, whose frozen sound waves reveal much that is now known about the ancient Universe.