Since the dawn of modern cosmology, dark matter has intrigued researchers with its fundamental role in the structuring of the universe while remaining practically elusive. This mysterious substance, which accounts for about 85% of the total mass of the invisible universe, profoundly influences the movement of galaxies and the evolution of large cosmic structures. Yet, … Read more
In the vast universe, the rotation of galaxies continues to fascinate astronomers who seek to understand the mechanisms behind this fundamental movement. The orientation of galaxies, often perceived as random, actually reveals a more subtle organization. The alignment of galactic spins – the preferred direction in which galaxies rotate – has become a key area … Read more
In the vastness of the universe, beyond the twinkling of galaxies, lie enormous regions practically devoid of visible matter, the cosmic voids. These areas, true depressions in the large-scale structure of the cosmos, offer a striking contrast to the dense filaments and galactic clusters that compose the cosmic web. Their characteristics, formation, and role in … Read more
In the vast field of cosmology, topological defects emerge as silent witnesses of the first fractions of seconds of the primordial universe. These unique structures, often stable, would have formed during cosmic phase transitions, crucial moments when the universe saw its fundamental symmetries break. These breaks left behind singular configurations of matter and energy, which, … Read more
Primordial nucleosynthesis, a fundamental phenomenon marking the chemical genesis of the universe, unfolded during the very first minutes following the Big Bang. It was during this intense phase that the first light atomic nuclei appeared, giving birth to elements that will constitute the fundamental building blocks of cosmic matter. This crucial step conditioned the cosmic … Read more
The cosmic microwave background, often referred to as fossil radiation, is an extraordinary witness of the primordial universe. Originating from the time when the first atoms could form, this radiation reveals the state of the Universe approximately 380,000 years after the Big Bang. However, far from being perfectly uniform, it presents small temperature variations known … Read more
In the depths of the cosmos, at a time when the Universe was in a state of transformation, a crucial phenomenon changed the very shape of everything that would become our cosmic environment. This phase, known as the cosmological recombination epoch, marks a decisive turning point in the history of the primordial Universe. Several hundred … Read more
Since the end of the 1990s, contemporary astronomy has revealed an unsuspected facet of our cosmos: a mysterious force, dubbed dark energy, which represents about 70% of the total energy density of the Universe and is responsible for the acceleration of its expansion. This phenomenon is intimately linked to the cosmological constant, a notion introduced … Read more
The cosmological horizon problem embodies one of the major challenges in modern cosmology, questioning the very foundations of our understanding of the observable universe. This conundrum raises a fascinating question: how can extremely distant regions of the universe, seemingly without any causal contact, exhibit such surprising homogeneity, particularly seen in the cosmic microwave background radiation? … Read more
In short: Contemporary cosmology, at the crossroads of theoretical advances and astrophysical observations, develops models where our universe, far from being unique, could coexist with a multitude of others. These cosmological theories of the multiverse, fueled by quantum physics and string theory, open a groundbreaking perspective: instead of an isolated Big Bang, the emergence of … Read more