Slightly less than five billion years ago, when the Sun began illuminating the still shapeless mass of what would become the planets of its system, the universe was already old. It had been created from seven to ten billion years earlier. It was the dawn of time, when there were no galaxies or stars, and not even life, but merely a very thick darkness. A "primeval atom" floated within this dark and ageless void, a sphere of extremely dense matter with a temperature of around one hundred billion degrees. Suddenly, perhaps due to some internal instability, the fireball exploded, projecting its fragments in all directions with inconceivable violence. Scientists have called this explosion the "big bang", and for several years, using all the laws known to physics and mathematics, they have been trying to discover what happened immediately afterwards: they have calculated that only one second later the temperature of the sphere, which had expanded to more than ten times its radius, dropped from one hundred to ten billion degrees. After one hundred seconds, the sphere was already one hundred times bigger and the first atoms of the lighter elements, namely hydrogen and helium, already had begun to form within its interior. While the expansion continued, scattering this mixture of the two gases into space, the temperature continued to drop until reaching 10 000 degrees after ten thousand years and 600 degrees after one million years. This is when something else took place: randomly in the darkness following the huge explosion, more than normal quantities of gas began to accumulate. These slightly thicker clouds, irregular chunks growing imperceptibly to the detriment of the area that surrounds them, are the proto-galaxies: through the force of gravity, they soon attracted greater and greater quantities of gas and, as their mass increased, they contracted, and became more compact and began to rotate faster and faster. Small fragments of denser matter then began to condense within these cosmic "pinwheels". The compact size of these clumps cause the atoms in their center to collide violently, increasing the temperature: all the hydrogen is transformed into helium and the excess energy, filtering through the gas spheres, reaches the surface and is irradiated outward. This is how the first star was born and illuminated the face of the heavens.
Slightly less than five billion years ago, when the Sun began illuminating the still shapeless mass of what would become the planets of its system, the universe was already old. It had been created from seven to ten billion years earlier. It was the dawn of time, when there were no galaxies or stars, and not even life, but merely a very thick darkness. A "primeval atom" floated within this dark and ageless void, a sphere of extremely dense matter with a temperature of around one hundred billion degrees. Suddenly, perhaps due to some internal instability, the fireball exploded, projecting its fragments in all directions with inconceivable violence. Scientists have called this explosion the "big bang", and for several years, using all the laws known to physics and mathematics, they have been trying to discover what happened immediately afterwards: they have calculated that only one second later the temperature of the sphere, which had expanded to more than ten times its radius, dropped from one hundred to ten billion degrees. After one hundred seconds, the sphere was already one hundred times bigger and the first atoms of the lighter elements, namely hydrogen and helium, already had begun to form within its interior. While the expansion continued, scattering this mixture of the two gases into space, the temperature continued to drop until reaching 10 000 degrees after ten thousand years and 600 degrees after one million years. This is when something else took place: randomly in the darkness following the huge explosion, more than normal quantities of gas began to accumulate. These slightly thicker clouds, irregular chunks growing imperceptibly to the detriment of the area that surrounds them, are the proto-galaxies: through the force of gravity, they soon attracted greater and greater quantities of gas and, as their mass increased, they contracted, and became more compact and began to rotate faster and faster. Small fragments of denser matter then began to condense within these cosmic "pinwheels". The compact size of these clumps cause the atoms in their center to collide violently, increasing the temperature: all the hydrogen is transformed into helium and the excess energy, filtering through the gas spheres, reaches the surface and is irradiated outward. This is how the first star was born and illuminated the face of the heavens.
