There was a phase of rapid expansion in the early universe called inflation. Cosmologists previously believed this expansion was powered by a newly discovered entity in the universe known as the inflaton. However, new research suggests that it may have been possible for the universe to inflate without the need for anything new to fuel that inflation.
In the 1970s, physicist Alan Guth proposed a radical concept of the very early universe. Initially created to address certain problematic characteristics of high-energy physics in the young, dense, hot universe, Guth developed a model where a newly introduced quantum field called the inflaton drove a brief yet intense period of tremendously accelerated expansion, increasing the size of the universe by many orders of magnitude in less than a second.
Inflation has been a compelling hypothesis of the early universe as it resolves several issues simultaneously. It explains why the cosmos appears to be geometrically flat despite its overall curvature, why regions separated by vast distances are similar, and how large-scale structures were formed.
However, many mysteries remain unanswered, such as the identity of the inflaton, its power source, and why it ceased. Additionally, there is no definitive proof that inflation occurred.
Considering these challenges, a recent paper by astrophysicists proposes a model where inflation, leading to the large-scale structure of the universe, could occur without the need for an inflaton to drive it.
This model describes a universe expanding due to a cosmological constant, reminiscent of dark energy observed in the modern cosmos, where quantum fluctuations generate gravitational waves that trigger the right kind of deformations in space necessary for structure formation.
Although there are differences between the structures formed in this scenario and traditional inflation, further research is needed to explore the observational implications of this model.
While this model is not without its flaws and assumptions about the early universe, it presents an intriguing alternative to traditional models that rely on an inflaton to drive changes in the early universe.
The mysteries of the young cosmos continue to puzzle modern cosmologists, emphasizing the ongoing quest for a deeper understanding of the universe.
