The Universe begins to resemble a city at night when you peer long enough into the heavens. Galaxies adopt the characteristics of streetlamps cluttering up neighborhoods of dark matter linked by gas pipelines that run along intergalactic nothingness.
After the Big Bang launched into space and time around 13.8 billion years ago, this Universe map was preordained and laid out in the faintest of shivers of quantum physics.
Yet, what exactly were those fluctuations and how they set in motion the physics that would allow us to see atoms pool into the huge cosmic structures we see today are still far from clear.
A recent mathematical examination of the moments following an inflationary epoch suggests that some sort of structure might have existed even within the shocking quantum furnace that blanketed the infant Universe, and it might help us better understand its structure today.
Astrophysicists from the University of Gottingen in Germany and the University of Auckland in New Zealand combined particle movement simulations and a sort of gravity/quantum modeling to anticipate how structures might evolve as a result of inflation.
The size of this type of modeling is something that's mind-blowing. At a time when the Universe was just 10-24 seconds old, we're talking about masses of up to 20 kilograms squeezed into a space barely 10-20 meters across.
"Our simulation's physical space would be a million times smaller than that of a single proton," said university of Gottingen researcher Jens Niemeyer.
"It is probably the most extensive investigation of the universe's tiny space that has been carried out."
The majority of what we know about this early stage of the Universe's existence is based on this kind of mathematical sleuthing. The oldest light we can still see flickering through the Universe is the Cosmic Background Radiation (CMB), and the entire show had already been on the road for around 300,000 years by then.
Despite the faint echo of ancient radiation, there are still traces of what was going on.
Basic particles combined into atoms out of the hot, dense energy soup of the CMB, in what's known as the epoch of recombination.
Our Universe already had some sort of structure by a few hundred thousand years ago, according to a map of this background radiation across the sky. There were little cooler bits and slightly warmer bits that might nudge matter into areas that would eventually see stars ignite, galaxies spiral, and masses pool into the cosmic city we see today.
This raises a question.
The universe's space is expanding, implying that the universe must have once been a lot smaller. Everything we see around us now was once crammed into a volume too small for such warm and cool patches to develop.
There was no way for any component to cool down before it heated up again, as a cup of coffee in a furnace.
The inflationary period was proposed as a way to remedy this problem. Within trillionths of a second of the Big Bang, our Universe exploded in size by an unbelievable amount, effectively halting quantum fluctuations.
To say this happened in a blink of an eye would still not do justice. It would have begun around 10-36 seconds after the Big Bang, and ended by 10-32 seconds. However, it was long enough for space to break into proportions that prevented small variations in temperature from resolving.
The researchers' calculations focus on this brief moment after inflation, demonstrating how elementary particles congealing from the foam of quantum ripples at that time might have created tiny halos of matter large enough to rip apart spacetime itself.
"The formation of such structures, as well as their movements and interactions, must have generated a background noise of gravitational waves," according to University of Gottingen astrophysicist Benedikt Eggemeier, the study's first author.
"We can calculate the strength of this gravitational wave signal, which might be measurable in the future," says the simulations.
The enormous amounts of such objects may have pushed matter into primordial black holes, objects thought to be involved in the mysterious pull of dark matter.
The fact that these structures behave as big-scale clumping of our Universe today doesn't necessarily mean they're directly responsible for today's star distribution, gas, and galaxies.
Nevertheless, the complex physics that emerges among those freshly baked elements might still be visible in the sky, among the mysterious landscape of twinkling lights and dark voids we refer to as the Universe.
This research was published in Physical Review D.
This version of this article will be published in March 2021.