In the beginning there was nothing.
The difficulty in defining it comes not from whether the lack was of matter or time or both. But from the fact the attempting to define it or even do as little as imagine it ends up destroying it due to the very nature of what an absolute nothingness is.
In fact, an old legend has been spoken amongst the most ancient civilizations of the universe, the ones that somehow managed to survive (or amongst the ruins of such). The legend goes on to say that a nothingness cannot withstand the tiniest attempt of being observed. Secondly another property of nothingness is that it's extremely unstable.
The legend is accompanied by a tale of a beings referred to as the Absolutes. The tale goes as such:
Before the currents of time, the fabric of space and before the galaxies and what we now refer to as the universe existed, there existed the Absolutes.
One thing that is universally true about any tale is that if told and repeated enough times, the fact and the fiction meld and it becomes impossible to tell where the fact ends and the fiction begins, given that there was any fact to begin with.
This tale is no exception to this rule.
The Absolutes, the story says, were people as in they had the ability to think and the power to act and change matter.
The story never goes into the details about what the Absolutes looked like, where they lived, what they ate etc.
Some local variations exist that vary by each version and mostly is done to make the absolutes the ancestors or distant relatives of the populace that it is told amongst.
As history researchers, we should treat such alterations to be of no consequence due to the understandable but inconsequential motive being to invoke racial pride.
Thus after deducing all the local modifications we can deduct certain common elements amongst all the variant.
Here, we will describe the story in as intact a form as can be told. What is considered the local modifications are taken out and no attempt to linearize the story for scholastic sake is made.
The Absolutes, it is said, had the ability to shape reality according to their will and did so whenever and however they desired.
Whether it was by accident or by intention, one amongst them conceived the notion of nothingness, the kind that cannot be imagined.
A few of them were deeply intrigued by the idea and while the story doesn't say whether they understood the implication, we can assume that they didn't or they wouldn't have done what followed.
They created a contraption that was designed to drain a portion of the reality from their dominion.
The contraption worked successfully and the success that it achieved was the doom of it's makers.
Nothingness is a highly unstable phenomena and while the creators celebrated their success and then took the instruments, attuning them towards the nothingness since they wanted to understand it's nature, it imploded.
The implosion was sudden and the absolutes disappeared with it.
Here we have two variants, each being equally popular.
The first version says that they were pulled into the implosion and destroyed.
The second version says that the side effect of the implosion was the beginning of time.
As the flow of time began, The Absolutes ceased to exist.
The rest of the story is lengthy and overly verbose.
It can be summarized into following:
The only thing remaining after the implosion was a tiny speck of dust in place where the nothingness had imploded.
The speck was infinitely small but was surrounded by an absolute nothingness.
The combination caused an explosion of incomparable scale.
Normally an explosion is scaled down by reality once the energy has dispersed from it.
However in this case, there was no reality to scale it down so it started expanding extremely fast.
The matter from whatever that speck contained poured out and the quick expansion caused it to reach the temperature of an extreme scale.
It ran hotter than the heat of a million suns and was denser than the centers of the all the galaxies combined.
As it poured out, portions of it collided with other portions.
It exploded, burned and within a few seconds since the flow of time had begun, formed the huge stars.
Those stars were the beginning of the universe.