When we look out into space beyond the borders of the Milky Way, we see a lot of people.The universe is full of galaxies, There were specks like stars in the darkness. If we stop here, it would be easy to assume that the distribution of galaxies is more or less uniform throughout space and time.
But there are ways to this madness. Rather than moving around freely, galaxies are drawn to matter by their mutual gravitational pull and tend to concentrate into clusters, clumps, and filaments in the cosmic web. highwaysuperhighways and nodes.
The opposite is a void, a region with relatively few galaxies and much lower density.
A growing body of evidence suggests that the Milky Way galaxy is drifting through one of the edges of one of these cavities in a small corner of the universe, a bubble of space apparently known as a local cavity.
previous measurements Researchers estimate the size of the cavity to be about 60 megaparsecs, or about 200 million light years. But that’s only part of the picture.
The local void may be swallowed by a much larger, lower density, about 600 megaparsecs in diameter, known as a local hole or Keenan-Berger-Cowie (KBC) supervoid.
This supervoid is a big problem because according to the standard model of cosmology, matter is more or less evenly distributed throughout the universe.
This standard model cannot account for such huge underdensities.
But now a new study led by astrophysicist Sergizh Mazurenko of the University of Bonn has found that perhaps local holes could solve the problem. hubble tensionincompetence Solve various measurements The rate at which the universe is expanding.
You just need to find a way around the standard model.
The rate of expansion of the universe is known as the Hubble constant, or H0. The exact percentage is not known because different measurement methods give different results.
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One way is to look at relics of the early universe, such as the light from the Big Bang, that remain in the universe. space microwave backgroundor Sound waves frozen in time. This gives it a speed of approximately 67 kilometers (42 miles) per megaparsec.
Another method is to measure the distance to a Type Ia supernova or a more recent, closer object of known brightness. Cepheid variable star. This works out to a speed of approximately 73 kilometers per second per megaparsec.
“Thus, the universe appears to be expanding faster near us, at distances of up to about 3 billion light-years, than as a whole.” says astrophysicist Pavel Krupa. PhD from the University of Bonn. “And actually, it shouldn’t be.”
The researchers found that this problem could be solved by considering local holes.
Matter attracts other matter through gravity. A galaxy moving away from us in local space can be locally accelerated by the concentration of matter around the edge of the supercavity.
It’s the same way of thinking as 2020 Papers This suggests that local voids have the same effect, but on a much larger scale.
The problem that remains is that cumbersome standard model. But if we use a different model for how gravity works, this becomes less of a problem.
It is called modified Newtonian mechanics (Mondo), and it was proposed 40 years ago as an alternative explanation to the dark matter theory, which was devised to resolve a discrepancy in the gravity measurements of the universe.
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“The Standard Model is based on Albert Einstein’s theory of the nature of gravity.” Kroupa says.
“But gravity may behave differently than Einstein predicted.”
MOND makes resolving local holes much easier. To be clear, Serious issues with MOND, too. But it’s worth using it as a tool to figure out where the holes are in our current understanding of the universe.
The real answer may lie somewhere closer to a blend of both theories. It doesn’t mean we need to abandon Einstein; we need to expand on it.
“Einstein is thought to have said that you cannot solve problems with the same thinking that created them in the first place.” Physicist Indranil Banik writes As stated in an article in The Conversation from the University of St. Andrews.
“We may well see the first reliable evidence in more than a century that our theory of gravity needs to change, even if the changes needed are not radical.”
This study Royal Astronomical Society Monthly Notices.