The Cosmic Web
Graphic representing the cosmic web of galaxies and the void of dark matter in between. Credit: NASA, ESA, and E. Hallman (University of Colorado, Boulder)

The most recent measurements of what makes up the universe has shown that normal matter come in at just 4.9%. To be clear, this means that planet, stars, and everything that we see around us is less than 5% of the universe.

So, where is the rest of it?

Well, dark matter comes in at 26.8% and there’s 68.3% dark energy. Now, new measurements add to our understanding of the scale of the universe and what it is made of.

A team of scientists from the Institute of Astro- and Particle Physics at the University of Innsbruck, Austria has published a paper in the Monthly notices of the Royal Astronomical Society that finds that enormous voids which galaxies are stretched around comprise about 20% of the mass of the universe, with galaxies making up just 1/500th of its volume.

The team did this with the help of data from the Illustris cosmological simulation project, which simulates the evolution and formation of galaxies. The simulation shows that galaxies are like filaments stretched around large voids, resembling a “cosmic web.” The researchers used this data to measure the mass and volume of these galaxies.

In the simulation, the universe is portrayed as a cube that measures about 350 light-years on all sides, and is roughly 12 million years old. I

The researchers found that, while 50% of the universe’s total mass resides within the galaxies, it is compressed into a volume that’s only 0.2% of the universe. 44% of the mass is found in the enveloping filaments, which means the remaining 6% of universal mass resides in the vast voids that make up 80% of the volume.

Into the Void

The team of researchers also found that about 20% of normal matter may have been transported into the void. They suspect this may have been caused by supermassive black holes. In other words, 20% of the universe may rest in expansive, unpopulated black voids—proverbial dead zones.

When matter that falls into the black holes, it gets converted into energy, that energy is then transferred to surrounding gas, leading to a massive outflow of matter that stretches out for thousands of light-years past the host galaxy.

Research team leader Dr. Markus Haider explains that the “simulation, one of the most sophisticated ever run, suggests that the black holes at the centre of every galaxy are helping to send matter into the loneliest places in the universe. What we want to do now is refine our model, and confirm these initial findings.”

Illustris is continuing to run new simulations as researchers seek to understand black hole output and the matter in the void.

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