The Mysterious Formation of Dark Matter Before the Big Bang.
Researchers at the University of Texas at Austin propose a revolutionary new theory that traces the origin of dark matter to an event that occurred just before the Big Bang. This discovery could revolutionize our understanding of the universe and its first moments of existence.
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A new theory to explain what was “before” the Big Bang
The Big Bang is the scientific theory that describes the origin of the universemarking the start of its expansion around 13.8 billion years ago. According to this theory, the universe began as an extremely hot and dense spot, which then exploded and continually expanded. Dark matter, on the other hand, is a hypothetical form of matter that neither emits nor absorbs light, making it invisible and detectable only through its gravitational effects on visible matter. It constitutes approximately 27% of the mass-energy of the universe and would have “exploded” according to classical observations, at the same time as the rest of the matter during the Big Bang, playing a crucial role in cosmic structures by influencing the formation and the movement of galaxies.
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The concept of cosmic inflation
Initiated by physicist Alan Guth in 1981, the theory of cosmic inflation suggests that the universe expanded rapidly, increasing its size by 10 to the power 26 times in just 10 to the power -36 seconds. This phenomenon played a crucial role in eliminating irregularities in the structure of the universe, which explains its uniform and homogeneous appearance despite its continuous expansion.
New theory on the origin of dark matter
The new study argues that inflation also contributed to the formation of dark matter through a process called “freeze-in.” Unlike existing models where particles created during inflation are quickly diluted, UT Austin researchers say dark matter was produced and preserved during this phase.
Two training scenarios explored
Scientists distinguish two potential processes for the formation of dark matter from the “thermal bath”, which brings together particles interacting at a given temperature during the formation of the universe.
Le “freeze-out”
Freeze-out suggests that dark matter was in thermal equilibrium with ordinary matter, freezing as the universe cooled. This is the vision “traditionally” shared by physicists but which was dismissed by the researchers of the study.
The 'Freeze-in' Model and Its Implications
The other scenario, the “freeze-in”, proposes that dark matter has never been in thermal equilibrium. It would be the result of rare energetic interactions, such as those involving UV radiation. During inflation, the quantum field responsible for inflation would have lost energy to this UV radiation, thus generating dark matter particles which then “froze” in the cooling universe.
A “disruptive” theory about the Big Bang
What distinguishes the model proposed by the UT Austin team is that these interactions would have occurred before the Big Bangduring the exponential expansion of the universe due to inflation. This perspective reverses the traditional idea that inflation and the freeze-in occurred after the Big Bang.
A new vision of the universe
This innovative theory offers a new window into the earliest moments of our universe and highlights the potential role of dark matter in early cosmic evolution. It also opens up perspectives for future research, particularly on the production of other particles which could have played a crucial role during the evolution of the universe.
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This article explores the bold proposal from researchers at the University of Texas, which suggests that dark matter could have been produced just before the Big Bang through a freeze-in process. This revolutionary idea challenges established theories about the timing of cosmic events and could have major implications for our understanding of the universe.
Source : Physical Review Journal
