![]() ![]() - Accelerating Universe and Dark Energy.- The Expanding Universe and Hubble’s Law.- The Big Bang and the Big Crunch Introduction.Main Topics > The Big Bang and the Big Crunch > Antimatter Topic Index: Taken from Hofstätter 2012.A Few Random Facts Where in the universe is the Earth? How fast are we traveling through space? How fast does light travel? How far is it to space, the Moon, the Sun, the stars, etc? How many stars are there? How does the Sun shine? What different types of stars are there? What is the human body (and the Earth, the Sun, the Universe) made of? How many molecules/atoms are there in each cubic meter? What if the history of the universe were squeezed into the period of one year? What are the coldest and the hottest objects in the universe? What is the electromagnetic spectrum? What is a planet? What is a dwarf planet? Why do the planets orbit the Sun? Protons are composed of quarks (and antiprotons of antiquarks), so these collisions involve more-complicated particle interactions. When electrons and positrons annihilate each other, they make gamma rays. Matter-antimatter collisions create different products depending on the starting particles. ![]() But who knows what secrets a hypothetical antiuniverse might hold and what a collision between an elephant and an antielephant would produce! We live in a predominantly matter universe. In principle it is possible to have anti-anything - antihelium, antioxygen, anticarbon, antielephant, antiearth. In the same way particles make up matter such as chemical elements – for example, hydrogen is composed of a proton and an electron – antiparticles make up antimatter – so a positron and antiproton make antihydrogen. Particle accelerators, like the Large Hadron Collider at CERN in Geneva, smash particles together in order to create antimatter – but it costs billions of pounds to make tiny amounts which are very difficult to keep for any length of time because they are quickly destroyed in a collision with their matter counterpart. In fact, trying to artificially make and keep antimatter is a difficult and expensive business. But this positron is very quickly annihilated by a passing electron. This is because they contain a particular type of potassium (called potassium-40) which undergoes radioactive decay releasing a positron every 75 minutes. These new particles will have a lower mass than those in the original collision, due to the law of conservation of energy and Einstein’s very famous equation E=mc2 – some of the energy goes into heat and light, some into forming the new particles.Īntimatter is all around us – for example bananas emit antimatter. Depending on the colliding particles, not only is there a great energy release, but new, different particles may also be produced (such as neutrinos and various flavours of quark – see figure below). ![]() When matter and antimatter collide, the particles destroy each other, with a huge energy release. For example, an electron (negative charge) and a positron (positive charge), or a proton (positive) and an antiproton (negative). Matter and antimatter are collections of particles which form particle pairs with the same mass but opposite electric charge. CERN – Universe of Particles (Photo by Michal Matlon on Unsplash)
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