New Physics Model Challenges the Big Bang Story We Thought We Knew

Scientists propose that gravitational waves shaped the universe. Their model challenges inflation theory.

How exactly did the universe start, and how did these processes determine its formation and evolution?

A recent study published in Physical Review Research takes on this challenge, as researchers from Spain and Italy introduced a new model to explain what happened immediately after the universe’s birth. Their work has the potential to question long-accepted ideas about the universe’s earliest moments and how those events influenced its later evolution.

To investigate, the team ran a series of computer simulations designed to test alternatives to the “inflation” theory, which proposes that the universe underwent a rapid expansion during the first fraction of a second after it formed. According to the inflation model, multiple factors must align to make such an expansion possible, making it a complex and still-debated explanation.

A new role for gravitational waves

The researchers instead suggest that gravitational waves, a phenomenon predicted by general relativity, could account for the formation of the universe and everything within it, from galaxies and stars to planets and life itself. They place these waves within the framework of De Sitter space, a mathematical model named after Dutch mathematician Willem De Sitter, who collaborated with Albert Einstein in the 1920s to explore the structure of the cosmos.

“For decades, we have tried to understand the early moments of the Universe using models based on elements we have never observed”, said Dr. Raúl Jiménez, who studies experimental sciences & mathematics at ICREA in Spain and is a co-author on the study. “What makes this proposal exciting is its simplicity and verifiability. We are not adding speculative elements but rather demonstrating that gravity and quantum mechanics may be sufficient to explain how the structure of the cosmos came into being”.

Gravitational waves through history

First proposed in 1893 and 1905 by Oliver Heaviside and Henri Poincaré, respectively, gravitational waves received a huge boost in attention in 1916 when Albert Einstein proposed them to be ripples in the space-time continuum as part of his general theory or relativity.

Despite myriads of sources, including supernovae, black holes, and neutron stars, gravitational waves are incredibly difficult to detect and require very sensitive instruments. This is potentially why gravitational waves were not detected until September 2015 by the Laser Interferometer Gravitational-Wave Observatory (LIGO) observatory, which have locations in Washington and Louisiana.

The origin of the universe remains one of the biggest mysteries in science, as the Big Bang has long been theorized to have been the catalyst for the origin of the universe. Despite ongoing scientific breakthroughs and advancements, scientists remain puzzled regarding the origins of the universe, and especially what might have happened before the Big Bang.

Searching for cosmic understanding

Carl Sagan famously said, “The cosmos is within us. We are made of star-stuff. We are a way for the universe to know itself.”

We may never know exactly how the universe began and the processes responsible for you reading this article right now. But like the simplicity this study presents, perhaps this study is simply a way for us to know the universe itself a little bit better.

What new discoveries about the origins of the universe will researchers make in the coming years and decades? Only time will tell, and this is why we science!

As always, keep doing science & keep looking up!

Reference: “Inflation without an inflaton” by Daniele Bertacca, Raul Jimenez, Sabino Matarrese and Angelo Ricciardone, 8 July 2025, Physical Review Research.
DOI: 10.1103/vfny-pgc2

Adapted from an article originally published on Universe Today.

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