Cosmic inflation would not explain the ultra-rapid expansion of the early Universe: this could suggest that the cosmos was not born from an initial burst.

A new study suggests that cosmic inflation, a point in the infancy of the Universe when space-time expanded exponentially and which is crucial to the Big Bang theory, could quickly be ruled out as a possibility by new discoveries. These findings would be possible in the coming decades, hand in hand with a great technical and scientific challenge.

Astrophysicist Sunny Vagnozzi of the University of Cambridge in the United Kingdom and her colleague Avi Loeb of Harvard University in the United States postulate in a new study recently published in The Astrophysical Journal Letters that the theory of cosmic inflation would be impossible to test and, therefore, could be quickly ruled out as a possibility to explain the expansion of the Universe in its early moments.

initial inflation Initially developed by the American physicist and cosmologist Alan Guth in 1981, cosmic inflation is one of the bases that support the idea of ​​the Big Bang: almost immediately after the initial burst, the Universe “inflated” rapidly and exponentially. This accelerated expansion would explain, among other things, why the current cosmos is so different from the primitive Universe.

Although this idea seems elegant at first and solves various enigmas about the initial moments of the cosmos, some scientists, including Avi Loeb himself, raised their concerns about cosmic inflation and the real possibility of verifying it, after the Planck satellite of The European Space Agency (ESA) will publish its first measurements of the cosmic microwave background (CMB), that is, the oldest light in the Universe. On that occasion, the results were presented as proof of the theory of cosmic inflation, but for Loeb and other scientists they were just the opposite: in their view, the Planck data showed that cosmic inflation posed more puzzles than they thought. resolved, and that it was time to consider new ideas about the beginnings of the Universe.

This would indicate that if the Universe did not expand rapidly at its inception, it probably did not arise from a primordial outburst, and therefore the Big Bang could also be ruled out. How then would the cosmos have arisen? For example, Loeb thinks it may have started by “rebounding” from a previously contracting cosmos.

Reference The Challenge of Ruling Out Inflation via the Primordial Graviton Background. Sunny Vagnozzi1,2 and Abraham Loeb. The Astrophysical Journal Letters (2022). DOI: https://doi.org/10.3847/2041-8213/ac9b0e