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Science’s best guess at how the universe came into being includes the Big Bang followed by a moment of rapid inflationary expansion.
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However, this theory left a few mysteries and quirks in its wake, including the existence of dark matter and conundrums like “the flatness problem.”
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A fringe theory known as non-singular matter bouncing cosmology claims to answer these issues by suggesting that the universe “bounces” between a hot big bang era and the kind of universe we see today.
Answering the question of how everything began was always going to be a difficult one, but humans have made incredible progress—especially considering that, in the cosmological blink of an eye, we’ve gone from writing on cave walls to carrying handheld computers around in our pockets.
The prevailing theory is that the modern universe formed after a cosmological Big Bang, followed by a period of rapid inflation. The expansion of the universe, the cosmic microwave background (CMB), and even the ages of the oldest stars supports this widely accepted theory. However, it’s also left a few nagging mysteries in its wake, and it’s these mysteries—such as dark matter and the “flatness problem,” which involves questions around why the observable universe appears to be flat—that have sent some scientists in search of other possible answers.
In a new paper published in the Journal of Cosmology and Astroparticle Physics, an international team of scientists explore the concept of a “non-singular matter bouncing cosmology.” Unlike the current model—which the paper refers to as the Hot Big Bang (HBB)—this proposed theory “bounces” between a hot, dense universe like the one seen during the Big Bang, and the much colder universe. In a way, according to the theory, the observable universe today is recycle from a previous universe.
Although this isn’t a new idea, the team explored the concept further by analyzing the existence of primordial black holes (PBH) in this controversial cosmological model.
“We found a novel natural model-independent mechanism for PBH formation during the HBB radiation-dominated era, within the context of non-singular matter bouncing cosmologies,” the authors wrote. “In particular, the enhancement of super-horizon curvature perturbations, during a matter contracting phase in combination with a short transitory period from the matter contracting to the HBB expanding Universe, can lead to enhanced curvature perturbations on small scales during the HBB phase, collapsing to form PBHs.”
According to IFLScience, this effectively suggests that primordial black holes—which are hypothetical and thought to have occurred not long after the Big Bang—could actually be observable remnants formed from disturbances during the chaotic transition phase of the early universe. These black holes have been suggested as a possible explanation for dark matter (though recent studies have shown that they’re likely too scarce to explain the mysterious phenomenon), but the researchers are adamant that this cosmological model solves both the flatness problem and the need for dark matter at all.
“Interestingly,” the paper reads, “the primordial black hole masses that we find can lie within the observationally unconstrained asteroid-mass window, potentially explaining the totality of dark matter.”
Although an intriguing idea, the Big Bang + Inflation model of the universe is still the modern cave man’s best bet at understanding what shaped our universe. But the researchers say it should be possible to figure out if this non-singular matter bouncing cosmology holds any merit as “enhanced curvature perturbations, collapsing to primordial black holes, can induce as well a stochastic gravitational-wave background.”
While it’s certainly possible that the Laser Interferometer Space Antenna (LISA) mission—which will essentially be a more powerful LIGO, but in space—could find something unexpected, this “bouncing” idea has a long way to go to prove itself against a cosmological model that’s served us well for decades.
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