It has been long believed that 70 percent of the universe is composed of dark energy, which makes it expand at an ever-increasing rate. However, a new model by researchers from the University of Copenhagen (UCPH) suggests that the expansion is due to a dark substance with a magnetic force, indicating that dark energy does not exist.
For many years, scientists have believed that 70 percent of the ever-accelerating, expanding universe is due to dark energy. The mechanism has been associated with an unknown repellant cosmic power called a cosmological constant, developed by Albert Einstein in 1917.
However, scientists cannot directly measure the cosmological constant, so a number of researchers, including Einstein himself, have begun doubting its existence, without suggesting a feasible alternative.
Now, a new study by UCPH researchers presented a model that replaces dark energy with a dark substance in the form of magnetic forces.
"If what we discovered is accurate, it would upend our belief that what we thought made up 70 percent of the universe does not actually exist," explained Steen Harle Hansen, an associate professor at the Niels Bohr Institute’s DARK Cosmology Center.
"We have removed dark energy from the equation and added in a few more properties for dark matter. This appears to have the same effect upon the universe’s expansion as dark energy."
The common understanding of how the universe's energy is distributed is that it has five percent normal matter, 25 percent dark matter, and 70 percent dark energy.
However, in this new model, the 25 percent share of dark matter is given special qualities that make the 70 percent share of dark energy unnecessary.
Image: Dark matter, which is invisible to the naked eye, illustrated with a blue color. Credit: NASA
"We don’t know much about the dark matter other than that it is a heavy and slow particle. But then we wondered--- what if the dark matter had some quality that was analogous to magnetism in it?" said researcher Steen Hansen.
"We know that as normal particles move around, they create magnetism. And, magnets attract or repel other magnets-- so what if that’s what’s going on in the universe? That this constant expansion of dark matter is occurring thanks to some sort of magnetic force?"
Hansen's question served as the new model's foundation, so the team developed it from the assumption that dark matter particles have some sort of a magnetic force. They then investigated the effect this force would have on the universe.
"It turns out that it would have exactly the same effect on the speed of the university’s expansion as we know from dark energy," said Hansen.
"Honestly, our discovery may just be a coincidence. But if it isn’t, it is truly incredible. It would change our understanding of the universe’s composition and why it is expanding."
"As far as our current knowledge, our ideas about dark matter with a type of magnetic force and the idea about dark energy are equally wild. Only more detailed observations will determine which of these models is the more realistic. So, it will be incredibly exciting to retest our result."
"Consistency analysis of a Dark Matter velocity dependent force as an alternative to the Cosmological Constant" - Loeve, K., et al. - Cosmology and Nongalactic Astrophysics - arXiv:2102.07792
A range of cosmological observations demonstrate an accelerated expansion of the Universe, and the most likely explanation of this phenomenon is a cosmological constant. Given the importance of understanding the underlying physics, it is relevant to investigate alternative models. This article uses numerical simulations to test the consistency of one such alternative model. Specifically, this model has no cosmological constant, instead the dark matter particles have an extra force proportional to velocity squared, somewhat reminiscent of the magnetic force in electrodynamics. The constant strength of the force is the only free parameter. Since bottom-up structure formation creates cosmological structures whose internal velocity dispersions increase in time, this model may mimic the temporal evolution of the effect from a cosmological constant. It is shown that models with force linearly proportional to internal velocites, or models proportional to velocity to power three or more cannot mimic the accelerated expansion induced by a cosmological constant. However, models proportional to velocity squared are still consistent with the temporal evolution of a Universe with a cosmological model.
Featured image credit: NASA
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