If the cosmos are a slice of Swiss cheese, the Milky Way exists in one of its holes, and we, the Earth dwellers, reside deep, deep, deep within that empty nothingness.
That's a theory coming from researchers at the University of Wisconsin in Madison—a state famous for its cheese, funny enough—who've been trying to learn more about our neighbourhood's massive void for the past several years. In 2013, one study found that the region surrounding our own galaxy has far fewer galaxies, stars, and planets in it than was expected. Now, new research, which is being presented today at a meeting of the American Astronomical Society in Austin, Texas, has given further weight to this theory.
If these researchers are right, the void we call home is the largest void known to science, with a radius of about 1 billion light years.
Cosmologists are working to understand the structures that make up our universe, which looks to be composed of normal matter, like galaxies, stars, and planets, as well as dark matter and dark energy. Neither of those have been directly observed, but are thought to make up about 95 percent of the entire universe.
Scientists had originally expected more stuff to exist in our cheese hole because of the cosmological principle, lead author Benjamin Hoscheit, who is an undergrad, told me over the phone. This theory says that one random area in the universe should have roughly the same amount of stuff (ie. planets, stars) as another random part.
The realization that different techniques used by astrophysicists to measure the Hubble Constant—which describes the expansion rate of our universe—give different results left Hoscheit thinking that just existing in a void could solve this problem.
"It's a constant," he said. "You should have the same value no matter how you measure it."
In a void, matter on the outside will have a stronger gravitational pull, affecting the Hubble Constant value when it's measured with a technique using nearby supernovae. It has no effect, though, on a value that comes from a different technique—one using the cosmic microwave background, which is light leftover from the Big Bang, and a way to study the early universe.
According to Hoscheit, this allows for a comparison to be made, and may help resolve some of the discrepancies between the ways cosmologists measure the expansion of the universe.
So can we now say that without a doubt we live in an overwhelmingly empty sector of space?
Of course not, this is science. But, these new findings are a part of the much larger effort to better understand the structure of the universe.
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