Dark Matter Created Before the Big Bang

Researchers from the University of Texas at Austin have introduced a groundbreaking model to explain the origins of dark matter, suggesting it was formed during the brief period before the Big Bang, when the universe underwent an extraordinary expansion known as cosmic inflation.

What Is Cosmic Inflation?

Proposed in 1981 by physicist Alan Guth, cosmic inflation describes a rapid exponential expansion of the universe, growing by a factor of 10²⁶ in just 10^-36 seconds. This event smoothed out irregularities in the universe’s structure, leaving it homogenous and uniform even as it continues expanding.

Dark Matter and the Freeze-In Scenario

The new model links cosmic inflation to the creation of dark matter, using a mechanism called the freeze-in scenario. According to Katherine Freese, the study’s lead author, “dark matter is successfully produced during inflation,” unlike other models where inflation wipes out anything created during this period.

Freeze-Out vs. Freeze-In

The study explores two possible scenarios for dark matter's formation:

Freeze-Out:

• Dark matter particles were once in thermal equilibrium with regular matter.
• As the universe expanded and cooled, these particles stopped interacting with regular matter, fixing their density.
• The researchers ruled out this theory, as thermal equilibrium would have been disrupted by the intense dynamics of inflation and the Big Bang.

Freeze-In:

• Dark matter particles were never in thermal equilibrium.
• Instead, they were produced through rare, high-energy interactions during inflation, such as those involving UV radiation.
• The team suggests that during warm inflation, the quantum field driving inflation lost energy to UV radiation, creating dark matter particles. These particles "froze in" as the universe cooled.

A Pre-Big Bang Twist

Unlike conventional theories, which place inflation and dark matter formation after the Big Bang, the WIFI (Warm Inflation via Ultraviolet Freeze-In) model proposes that dark matter originated before the Big Bang during the inflationary phase. This shift challenges traditional views of the universe's early evolution.

Implications for Future Research

The WIFI model opens doors for exploring the production of other particles during inflation that may have influenced the universe’s early development. According to co-author Barmak Shams, “WIFI suggests broader applicability,” offering new opportunities for theoretical and observational research.

While this model provides a novel perspective, it remains a theory. Observational validation of the WIFI model could take years, but its potential to reshape our understanding of the universe's origins is significant.