This artist’s impression pinpoints many cosmic voids –– relatively empty bubbles of space.
The universe is home to trillions of galaxies, each chock full of smaller cosmic objects like stars and planets. Since galaxies gravitate together in a web-like pattern, there are also immense open spaces called cosmic voids in between. In those growing, gloomy places, dark energy dominates.
Galaxies in this animation are structured a bit like a Hoberman sphere (a lattice-like toy ball that expands and collapses), growing farther apart as the universe expands.
Zoomed out maps of the universe show that galaxies often cluster together in bright city-like regions. Each cosmic metropolis is connected to others by interstate highways – vast filaments of dark matter, gas, and dust, along which additional galaxies can be found. This large-scale structure is called the cosmic web.
Way out in the boondocks – far from the galaxies and filaments – are the cosmic voids. They’ve been growing larger for billions of years, emptying out as gravity pulls matter elsewhere.
This animation visualizes the early universe, when the cosmic was full of a hot plasma soup.
Cosmic voids were born when the universe looked extremely different than it does today. Instead of being speckled with stars and galaxies, the cosmos was filled with a sea of plasma (charged particles) that formed a dense, almost uniform fluid.
There were slightly denser kernels of matter, like a single ounce of cinnamon sprinkled into about 13,000 cups of cookie dough! Since the clumps had more mass, their gravity attracted additional material. Those areas grew and grew, drawing more matter together to form stars, galaxies, and galaxy clusters as the universe expanded over billions of years. Meanwhile, the spaces in between became ever emptier.
A simulation of large-scale structure forming under the influence of gravity.
Cosmic voids aren’t completely empty, though. They do have sparse galaxies, though they seem to have delayed development. Since there’s less matter, there’s weaker gravity pulling things together so stars and galaxies form more slowly. And those galaxies are isolated so they’re less likely to interact with others, which fuels growth in denser places like galaxy clusters.
But voids are mostly filled with things we can’t see. They contain a thin mist of dark matter along with a relatively larger amount of WIMPS (weakly interacting massive particles) like ghostly neutrinos than we find elsewhere in the universe. Since there’s not very much stuff in voids to create gravity, a different force reigns supreme: dark energy, the mysterious cosmic pressure that seems to be speeding up the universe’s expansion. Since cosmic voids are influenced primarily by dark energy, they offer clues about its behavior.
Astronomers haven’t thoroughly studied cosmic voids yet, but our upcoming Nancy Grace Roman Space Telescope will be wide-eyed enough to reveal those desert patches of space like we’ve never seen them before. Studying them will show how the universe is put together and how dark energy is pushing galaxies apart.
If you could fly through the cosmic web at hyperspeed, you might see a view like this simulated one!
So far, scientists have found around 1,000 cosmic voids. Roman’s 3D surveys should find tens of thousands more, both large and small, scattered throughout earlier cosmic eras than previous large sky surveys could see. That means we’ll be able to watch how the most vacant places get even emptier over billions of years. And astronomers can trace any changes in dark energy’s might by seeing how it stretches voids, where dark energy dominates, across cosmic time.
Follow along with Roman’s journey to launch at nasa.gov/roman.
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so today a public health official guy came into my class to give a lecture on disaster awareness and he was talking about house fires and mentioned that the reason people most likely die during a house fire is because they refuse to leave their pet inside or they go back to get their pet. and right when he said this my friend immediately turned his head and looked at me and in that moment I had the most complete and genuine acceptance take over my body. I would 100% in front of my family and Jesus himself walk straight back into some raging inferno that was once my house to go get my fat cat. I nodded back
the best part of this post is reading all the tags from animal people who would also go back to save their pets. like no hesitation. walk backwards from heaven straight back into hell. someone even said they would go back for their fish. amazing
If you are a person who would walk into a blazing inferno for your animal, and your pet has free movement around the house, here’s a training exercise that could help save you both:
1) Set off your smoke alarm or play the sound on your phone (if your home has no smoke alarms, pease get some!)
2) stand BY THE FRONT DOOR to hand out treats
Do this a couple times and then keep it up NO EXCEPTIONS. Accidentally set the alarm off cooking? Treats by the door. Smoke alarm sound on TV? Treats by the door. Changing your smoke alarm batteries twice a year like you’re supposed to? Give them a test run and your pets get treats by the door.
Most dogs and cats will clue in VERY quickly that hearing that specific sound means go to the front door and wait for treats.
If there’s an emergency and even if you leave by another way, you will still know the most likely place your pet(s) is and can direct first responders to help.
You can also do this for any other kind of emergency alarm. My friend had both her cats trained to go to the front door for a tsunami siren.
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