The Cosmic Web of the Tarantula Nebula

Photo by: Josep Drudis

Josep Drudis

The Eeriest Place in the Universe

Imagine being completely, utterly alone. Surrounded by no planets, no stars, no galaxies. Not a single scrap of matter – not even a hydrogen atom – within hundreds of millions of lightyears. Welcome to the loneliest place in the cosmos: the great cosmic voids.

October 19, 2021

At the very largest scales, our universe is absolutely, breathtakingly beautiful. If you zoom out far enough – taking the biggest of big pictures – to the point where entire galaxies become nothing more than tiny dots of light, an amazing pattern emerges.

We call it the cosmic web.

Long, thin ropes of galaxies hundreds of thousands of lightyears long. Dense clumps, the clusters, home to thousands of galaxies. Vast, broad, imposing walls. The matter in our universe is arranged into this grand, weblike pattern that stretches from one end of the cosmos to the other. It is, by far, the largest pattern found in nature.

The Cosmic Web of the Tarantula Nebula

The Cosmic Web of the Tarantula Nebula.

Photo by: Damian Peach

Damian Peach

The Cosmic Web of the Tarantula Nebula.

And between all those glittering lights and impressive structures? Vast, empty expanses of almost absolutely nothing. The cosmic voids.

By sheer size, the cosmic voids are the largest objects in the universe. The smallest ones are already over 20 million light-years wide, while the largest stretch across a healthy fraction of the observable universe.

By volume, most of the universe is void. Only a small percentage of the universe is bound up inside the relatively thin walls, filaments, and clusters. No matter where your home galaxy lives in the universe, it’s never far from the abyss.

And what’s even worse: the voids are growing. You see, the cosmic web isn’t static, fixed, unchanging. It’s a dynamic, living entity that changes with time. Billions of years ago, our universe was pretty much even from place to place: roughly the same amount of matter wherever you went. But some places, by pure luck, had slightly more mass than others. That extra mass gave those regions an extra gravitational tug, causing even more material to pile up on those clumps.

This image from NASA's Hubble Space Telescope shows the inner region of Abell 1689, an immense cluster of galaxies. Scientists say the galaxy clusters we see today have resulted from fluctuations in the density of matter in the early universe.

This image from NASA's Hubble Space Telescope shows the inner region of Abell 1689, an immense cluster of galaxies.

Photo by: NASA/ESA/JPL-Caltech/Yale/CNRS


This image from NASA's Hubble Space Telescope shows the inner region of Abell 1689, an immense cluster of galaxies.

As structures began to grow and evolve over time, the voids emerged, expanded, and grew.

The evolution of the cosmic web isn’t finished. What we see now is a snapshot, a brief moment in time when the web is at its most magnificent. But as time marches on, our universe continues to expand, spreading itself apart and driving the cosmic web to get thinner and thinner.

Over eons, the filaments will stretch so thin they’ll vanish. The walls will dissolve. All that will remain will be the clusters, dense but small knots of galaxies.

In only 10 billion years, roughly twice the current age of the universe, the voids will merge together and grow, coming to dominate the universe and envelope it in darkness, with only the clusters acting as drifting life rafts of heat and warmth, adrift in an otherwise formless cosmic ocean of night.

Dive Deeper into the Cosmos

Journey Through the Cosmos in an All-New Season of How the Universe Works

The new season premieres March 24 on Science Channel and streams on discovery+.

Paul M. Sutter

Paul M. Sutter is an astrophysicist at Stony Brook University and the Flatiron Institute, host of Ask a Spaceman and Space Radio, and author of How to Die in Space.

Next Up

How Exoplanets Became the Next Big Thing in Astronomy

To date, we know of over 5,000 planets outside the solar system. And astronomers suspect that there may be *checks notes* around a trillion more in our galaxy alone. The search for exoplanets is one of the hottest topics in astronomy, with expensive telescopes and giant collaborations all searching for the holy grail of the 21st century: an Earth 2.0, a habitable world like our own.

How Astronomers Use a Trick of Gravity to See the Most Distant Objects in the Universe

Let’s say you’re an astronomer (work with me here) and you want to take a picture of something incredibly, deeply far away. You know, the typical business of astronomy.

South Korea Joins Space Race by Sending its First Spacecraft to the Moon

South Korea is launching its first lunar probe to the moon on August 4th. The Korea Pathfinder Lunar Orbiter (KPLO) or Danuri, developed by the Korea Aerospace Research Institute (KARI) is being launched to study moon carters, magnetic fields, and surface weathering.

NASA Launches CAPSTONE to Test Experimental Orbit Around the Moon

In preparation for future missions, NASA is testing a never-been-flown-before orbit around the Moon in search of the most efficient deep space route for space travel.

The Perseid Meteor Shower Reaches its Peak

Stargazers rejoice! The annual Perseid meteor shower is upon us. Here's what you need to know...(updated August 11, 2022)

A Guide to this August’s Best Astronomy Attractions

Learn more about the exciting things happening in the night sky this month! From the rings of Saturn to the most popular meteor shower of the year, August 2022 has us stargazing all month.

Scientists Have Discovered Enormous Balloon-Like Structures in the Center of Our Galaxy

There's something really, really big in the middle of our Milky Way galaxy — one of the largest structures ever observed in the region, in fact.

Why Astronomers Care About Super-Old Galaxies?

A long time ago, our universe was dark.It was just 380,000 years after the big bang. Up until that age, our entire observable cosmos was less than a millionth of its present size. All the material in the universe was compressed into that tiny volume, forcing it to heat up and become a plasma. But as the universe expanded and cooled, eventually the plasma changed into a neutral gas as the first atoms formed.

What We’ve Already Learned From James Webb? (Hint: it’s a lot)

That was worth the wait. Just a quick handful of months since its historic launch on Christmas Day, the James Webb Space Telescope has flown to its observing position, unfolded its delicate instruments and ultra-sized mirror, and run through a suite of checks and alignments and calibrations. The team at NASA behind the telescopes released their first batch of images from the science runs, and besides being gorgeous, they're powerful.

6 Months in Space Permanently Ages Bones by 10 Years

Astronauts on long-term space missions can experience bone loss equivalent to two decades of aging. New research suggests more weight-bearing exercises in space could help offset that decline.

Related To: