translated_content> The critical density of the universe: cosmological balance

La densité critique de l'univers : équilibre cosmologique

IN BRIEF Critical density : key value characterizing the energy of the Universe. Relationship between the density of the Universe and its curvature. Impact of a density lower than critical density: eternal expansion. Consequences of a density higher : possibility of a Big Crunch. Standard cosmological model based on general relativity. Measurement of critical density: … Read more

Cosmic filaments: structure of the universe

Les filaments cosmiques : structure de l’univers

IN BRIEF Cosmic filaments: thread-like structures made up of galaxies and galaxy clusters. Comprise the cosmic web, a complex network of empty spaces surrounded by walls of matter. Filaments can extend for hundreds of millions of light-years. First observed, they reveal the largest cosmic structures in rotation. Organize the matter of the Universe on a … Read more

Numerical simulations in cosmology: creating the universe in the laboratory

Les simulations numériques en cosmologie : créer l'univers en laboratoire

IN BRIEF Numerical simulations to study the Universe. Used by physicists to simulate the inflation of the Universe. Objective: to create a model of the entire observable Universe. Analysis of stars, galaxies, black holes, etc. Essential tool for understanding cosmological processes. Simulations aiding in retracing the history of the Universe. Illustration of the ongoing expansion … Read more

The fundamental forces that govern the universe

Les forces fondamentales qui régissent l'univers

IN BRIEF Four fundamental forces: gravitation, electromagnetism, strong nuclear force, and weak nuclear force Gravity: governs weight and the trajectories of celestial bodies Electromagnetic force: regulates interactions between charged particles Strong nuclear force: holds protons and neutrons together in the atomic nucleus Weak nuclear force: responsible for nuclear transformations Standard model: theorizes the fundamental interactions … Read more

The influence of quasars on the evolution of galaxies

L'influence des quasars sur l’évolution des galaxies

IN BRIEF Quasars: Immense black holes at the heart of galaxies. Energy emission: They produce significant amounts of energy by devouring matter. Cosmic evolution: Help in understanding the evolution of the Universe. Interaction with galaxies: Influence the formation and evolution of galaxies. Quasar winds: Produce jets of radiation altering the galactic environment. Energy role: Among … Read more

The fluctuations of the cosmic microwave background

Les fluctuations du fond diffus cosmologique

IN BRIEF Cosmic Microwave Background (CMB): fossil radiation of the universe Fluctuations: temperature differences, indicating anisotropies Blue regions: cooler, indicating areas of low energy Red regions: warmer, signaling areas of high energy Inflation: early period of the universe explaining certain fluctuations Measurements by satellites WMAP and Planck CMB reveals characteristic B modes Temperature dipole: origin … Read more

The large ground-based telescopes for cosmology

Les grands télescopes terrestres pour la cosmologie

IN SHORT Gran Telescopio de Canarias: Primary mirror with a diameter of 10.4 meters. European Extremely Large Telescope (ELT): Expected to open in 2027 with a mirror of 39 meters. Very Large Telescope (VLT): Flagship equipment of European astronomy. Southern African Large Telescope (SALT): Mirror of 11.1 meters. Schmidt Telescopes: Used for photographic astrometry. Large … Read more

The formation of the first atoms after the Big Bang

La formation des premiers atomes après le Big Bang

IN BRIEF Primordial nucleosynthesis: Formation of the first atoms after the Big Bang. Timing: Approximately 380,000 years after the Big Bang. Elements formed: Mainly hydrogen and helium. First molecule: The ion HeH+, possibly the first molecule. Conditions: Initial temperatures around 10^9 K. Electrons and atoms: Electrons combine with nuclei to form atoms. In the vastness … Read more

The great discoveries of the Planck satellite

Les grandes découvertes du satellite Planck

IN BRIEF Satellite Planck launched in 2009 by the European Space Agency. Objective: to map the anisotropies of the cosmic radiation. Discovery of a supercluster of galaxies through its imprint on the cosmic background radiation. Analysis of the cosmic microwave background, light emitted 380,000 years after the Big Bang. Onboard instruments: Low Frequency Instrument (LFI) … Read more

The concept of time in cosmology

Le concept de temps en cosmologie

IN BRIEF Cosmic time: central concept in cosmology to model the universe. History of objects: each element of the universe has its own temporal journey. Cosmological models: assume uniformity and isotropy of the universe. Coordination of events: necessary interaction between time and space to structure the universe. General relativity: revolutionized the perception of time in … Read more