Rocks & Minerals [antikvár]

THE FORMATION OF THE UNIVERSE WHEN WE LOOK TODAY at rocks and minerals, and at the planet Earth formed from them, it is hard for us to imagine a time when none of this existed - a time even before there were chemical elements, the building blocks from which rocks and minerals are made. Yet ^^^^^ between 13,000 and 15,000 million years ago, the entire ^^ Universe consisted of one tiny dot of primordial energy. Then, in an instant, the Big Bang set in motion a chain of events that resulted in the creation of atoms and, over millions of years, in the formation of galaxies and stars. It was only within stars that the elements were formed that would make minerals, rocks, and planets. COSMIC BACKGROUND This image shows the Cosmic Microwave Radiation Bactiground, a faint heat radiation that emanates from all points in the sky. It is thought to be left over from the firebaii-iike conditions prevaient in the early Universe. PARTICLE TRACKS Studying the tracks of subatomic particles in a partidé accelerator gives scientists insight into the Big Bang's early stages. m iM THE BIG BANG According to the most widely held theor)' of how the Universe came into being, the physical Universe and all within it emerged from an infinitely small point of pure energ}' in a highly compressed state and at an extremely high temperature. The rapid expansion of this point of energy through the Big Bang resulted in a relatively rapid drop in its density' and temperature, and within a few seconds a number of elementar)' particles, such as electrons, photons, neutrons, and protons formed. This expanding mass of energy and particles was still far too hot for the formation of atoms, an event that required perhaps another 300,000 years of expansion and cooling. Only then did Ihe first atoms appear, chiefly of hydrogen and helium. AFTER THE BIG BANG In the first few bilUonths of a second after the Big Bang, the Universe consisted of a "soup" of enormously varied particles and radiation. "Up" quark , i/uo • A • ^ QUARKS BIND In the next seconds quarks started binding to form protons and neutrons One "down" and two "up" quarks made a proton, while one "up" and two "down" quarks made a neutron. EDWIN HUBBLE American astronomer Edwin Hubble (1889-1953) is famous for proving that we live in an expanding Universe. Hubble made his most important discoveries in the 1920s. He found that other galaxies exist beyond our own galaxy, the Milky Way. By analysing changes in the wavelength of light from these other galaxies, he showed that they are moving away from the Milky Way, and that the further away a galaxy is the faster it recedes. As a result, Hubble concluded that the Universe as a whole is expanding. His crucial observations led directly to the Big Bang theory. , Electron Single J proton Energy ( W j released by ^ collisions I Electron ^^ Helium nucleus, two proti and two NUCLEI FORM Between 1 and 180 seconds after the Big Bang, collisions between protons and neutrons formed the nuclei of light elements, mainly helium, though they did not yet capture electrons. ATOMS APPEAR Afier about 300,000years, helium nuclei began to capture pairs of electrons, Arming helium atoms. Protons captured one electron each, forming hydrogen atoms.