Many models have been used to predict the existence of invisible strings stretching across space. In new research, scientists find how these cosmic strings might snap and how we could feel the fallout.
What are Cosmic Strings?
Cosmic strings refer to the hypothetical leftover from the universe's earliest moments. This idea was first envisioned by quantum field theorist Tom Kibble in 1976.
As the universe cooled within the first second of the Big Bang, it underwent intense rounds of phase transition, breaking the unified electromagnetic and weak forces into the distinct forces we observe today. Scientists believe that since these transitions were imperfect, each one left flaws in space-time itself.
Such defects could have taken on different shapes and properties, depending on the physics details that happened in those early days. Cosmic strings are likely one of the most common of these defects.
Experts have yet to find clear evidence for cosmic strings' existence; they will manifest as truly exotic objects if they do exist. As one-dimensional objects, cosmic strings have a thickness no wider than a proto and would stretch from one end of the cosmos to the other. These wrinkles would be so dense that a mile of string would outweigh Earth's entire planet. Other scientists also suggest that cosmic strings would also be nearly indestructible.
Understanding the Cracks of the Universe
Scientists used to believe that cosmic strings are stable. Once they form, they exist from the earliest moments of the Big Bang to the present time.
It is assumed that the only way to diminish a cosmic string would be to intersect them or if one string looped over on itself. Once it happens, the ensuing vibrations would force the cosmic string to decay into a shower of particles and high-energy radiation.
However, no such signals from cosmic strings have been found yet, and scientists have not uncovered evidence of their existence. This presents a challenge for cosmology since many models of the early universe predict the existence of quantum strings. If these one-dimensional wrinkles were made in abundance during the Big Bang, where they all went remains a mystery.
In a new study, researchers from the Kavli Institute for the Physics and Mathematics of the Universe in Japan suggest that the cosmic strings are perhaps not as stable as they were once thought. Instead of being stable, they might be "metastable". Metastability refers to a phenomenon found throughout the physical realm and occurs when a system finds itself in a stable position, remaining there indefinitely. However, any shift from that position could cause the system to find a new arrangement.
The researchers discovered that other exotic entities, like the magnetic monopoles, can destabilize cosmic strings. Near cosmic strings, monopoles can be created with anti-monopoles where they will promptly annihilate each other. During this process, the energy released can cut a cosmic string in half and trigger a destabilization process that would force the cosmic string to dissolve.
As the cosmic string dissolves, it causes a vibration that triggers the formation of gravitational waves. This explains why there may not be many cosmic strings left in the universe and why we have not found any so far.
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