Our universe has an antiuniverse twin, new research suggests

[May 20, 2023: Staff Writer, The Brighter Side of News]

Physicists in Canada propose that our universe could be a reflection of an antimatter universe that existed before the Big Bang, preserving the CPT symmetry, a fundamental law of physics. Their new cosmological model suggests the presence of an "antiuniverse" that mirrors our own universe.

According to conventional cosmological models, the universe, which includes space, time, and mass/energy, originated from an explosion about 14 billion years ago. Subsequently, it has been expanding and cooling, resulting in the gradual development of subatomic particles, atoms, planets, and stars.

Neil Turok, a researcher at the Perimeter Institute for Theoretical Physics in Ontario, suggests that current models of the universe's origin, such as inflation, rely too heavily on arbitrary parameters and are reminiscent of Ptolemy's description of the solar system.

Turok argues that the approach of inventing new particles or fields to explain new phenomena may be misguided. Instead, he and his colleague Latham Boyle sought to develop a model that explains all observable phenomena using only known particles and fields. They sought to extend the universe beyond the singularity of the Big Bang, where general relativity breaks down, and found a natural way to do so.

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Turok and Boyle's approach focused on extending the universe beyond the Big Bang singularity and out the other side using only known particles and fields. According to Turok, their model can explain all observable phenomena, without relying on ad-hoc parameters such as inflation.

Turok criticizes the approach of explaining new phenomena by inventing new particles or fields, suggesting that it may be misguided. Instead, he and Boyle developed a natural way to extend the universe beyond the Big Bang singularity using only known particles and fields, resulting in a model that can explain all observable phenomena.

Turok proposed a solution to the issue by postulating that the entire universe adheres to CPT symmetry. This fundamental principle states that any physical process remains unchanged if particles are replaced with their antiparticles, space is inverted, and time is reversed. However, Turok claims that the universe we observe violates this principle since time progresses forward as space expands, and there is an asymmetry between matter and antimatter.

According to Turok, the universe that upholds this symmetry is a pair of a universe and an antiuniverse. The antiuniverse would stretch back in time from the Big Bang and expand as it goes, dominated by antimatter with its spatial properties inverted in comparison to our universe. Turok likens this scenario to the creation of electron-positron pairs in a vacuum.

In collaboration with Kieran Finn from Manchester University, Turok acknowledges that their model still requires significant improvements and may face criticism from various detractors.

The paper was reviewed by referees for Physical Review Letters, and Turok mentions that they had a prolonged discussion over the temperature fluctuations in the cosmic microwave background. The referees insisted on an explanation for the fluctuations, while Turok's team stated that it was a work in progress. After much debate, the paper was eventually published.

In explaining the fluctuations, Turok suggests that they are a result of the quantum-mechanical nature of space-time close to the Big Bang singularity. While the far future of our universe and the distant past of the antiuniverse are fixed classical points, all possible quantum-based variations would exist in between.

Turok and his colleagues tallied the number of instances for each configuration of the CPT pair and determined the most probable existence. According to Turok, their findings indicate that the most likely universe is one that bears resemblance to our own.

According to Turok, the existence of quantum uncertainty implies that the universe and antiuniverse are not perfectly symmetrical to each other, thereby avoiding complex issues such as free will.

Despite the challenges, Turok suggests that the new framework presents a possible explanation for dark matter. A "sterile" neutrino, an extremely elusive and massive particle, is considered a natural contender to account for the finite mass of the more prevalent left-handed neutrinos.

Turok has proposed that CPT symmetry can be used to calculate the abundance of right-handed neutrinos in the universe based on observable data. Using the density of dark matter, he has determined that the mass of the right-handed neutrino is approximately 5×108 GeV, which is 500 million times greater than the mass of a proton.

Interestingly, this mass is similar to the one derived from anomalous radio signals detected by ANITA. The experiment, which usually observes cosmic rays travelling down through the atmosphere, detected particles travelling up through the Earth on two occasions with masses between 2 and 10×108 GeV.

Weiler and his colleagues have suggested that these particles were decaying right-handed neutrinos, as ordinary neutrinos would likely have interacted before reaching that distance.

However, Turok has pointed out that the CPT symmetric model requires these neutrinos to be completely stable, which poses a challenge. Nevertheless, he remains hopeful and notes that some adjustments to the model could allow for their decay over the age of the universe.

Although the team has not yet demonstrated whether their model can account for certain observations explained by the inflation scenario, it provides a natural explanation for dark matter. In a CPT-symmetric Universe, large numbers of superheavy sterile neutrinos would be produced. These neutrinos could also explain the high-energy cosmic-ray showers recently observed.

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