Jazzy D's Soul Notes

Rather than a big bang a recent theory has suggested that it was a big silence.
Despite a promising name, the Big Bang was silent — a sudden burst of energy in which time and space began, forming the Universe as it spread. With no space to expand into, there could be no medium around it into which sound waves could possibly propagate. But, in cosmic terms, the Universe was not silent for long — 380,000 years later (a mere 0.0003 per cent of its present age), it was filled with sound. And, this was not the random roar of white noise that one might perhaps expect — it was a sound with a pitch: it had a characteristic wavelength.

It would not, however, have been an audible sound to any eared creatures, could they have existed so far back in time, before even the stars were born: a vast object like the Universe makes a very low sound indeed — about one trillionth of a hertz.

The reason that there was such a vast deep tone in the infancy of space and time is closely connected to one of the most mysterious and important aspects of the Universe’s history: structure, of which sound is a signpost. If the Universe had remained as it began, a completely homogenous, smoothed-out volume of energy, then galaxies, stars, and people could not exist today. But, for reasons that are still unclear, there was a clumpiness in the early Universe — some areas were a little denser than others, and it was these denser areas that would eventually become stars and galaxies. Density means gravity, and gravity attracted nearby matter (then in the form of plasma — a ‘gas’ of ions). the motion of that matter caused compression, heating the plasma, which in turn increased its output of radiation. The force of this radiation counteracted the gravitational force, and so the compression became an expansion — and it is this cycle of compression and expansion that formed the primordial sound waves.