Mind Bending Science Simply Explained

brain-baffling ideas

Apparently, US physicist Richard Feynman used to say that “nobody understands quantum physics”. Phew! There we all were thinking that if we couldn’t get our heads round General Relativity, string theory or multiverses that we were destined to never win another pub quiz again. And Feynman even won a Nobel prize. But, while hard physics topics like these can bend the mind, in this special issue of BBC Focus, we’ve enlisted the experts to explain in no-nonsense, down-to-earth, jargon-free lingo exactly how the Universe works, from the most minuscule of subatomic particles to the biggest of cosmological concepts. We’re not saying it’s easy to understand. Indeed, Danish physicist Niels Bohr (who won the 1922 Nobel prize in Physics) also reportedly said: “If anybody says he can think about quantum theory without…

atom smasher

The Large Hadron Collider (LHC) is the world’s largest and most powerful particle accelerator. It sits in a 27km-circumference tunnel at CERN, 100m below the France-Switzerland border. Inside the tunnel, two beams of protons moving within a whisker of the speed of light collide head-on, recreating the conditions that existed around the time of the Big Bang. The beams are made to smash together at four different particle detectors around the ring: ATLAS, CMS, ALICE, LHCb. MICHAEL HOCH/CERN, GETTY, CDS/CERN…

how do we know what matter is made from?

Matter. Stuff. Everything we can see is made from atoms, each with electrons surrounding a tiny nucleus. And inside the nucleus are protons and neutrons, each made of quarks. Add a horde of neutrinos flying around us, elusive and insubstantial, and that’s where it stops. So says the Standard Model of particle physics, the best theory we currently have for explaining what all the visible matter in our Universe is made from. But how do we know this? Much of our knowledge comes from scattering experiments – that is, bouncing one thing off another. We have discovered new elements, and new fundamental particles, by carrying out scattering experiments at high-energy particle accelerators around the world. But scattering isn’t the only way to find out what the Universe is made of… our…

timeline

1897 JJ Thomson shows that the ‘rays’ emitted in a cathode ray tube are tiny particles, 2,000 times lighter than a hydrogen atom. The subatomic particles are electrons. 1909 Physicist Theodor Wulf discovers more charged particles at the top of the Eiffel Tower than the bottom, due to ‘cosmic rays’ from space. He developed one of the first detectors for atmospheric radiation. 1910 New Zealand-born physicist Ernest Rutherford investigates the scattering of alpha rays and the inner structure of the atom which caused the scattering, leading to his idea of a ‘nucleus’ – his greatest contribution to science. 1928 Paul Dirac devises an equation capable of describing electrons moving at ‘relativistic’ speeds – close to the speed of light. The equation predicts the existence of antimatter. 1956 Chinese-American physicist Chien-Shiung Wu observes that the weak force has ‘handedness’ –…

standard model of elementary particles

These are the elementary particles, which together make up the Standard Model of particle physics. All of the atoms in the Universe are built using only the electrons and the ‘up’ and ‘down’ quarks. These interact with each other and stick together with the help of gluons and photons. Gluons transmit what is known as the ‘strong force’ that binds together quarks to make protons and neutrons, the building blocks of atomic nuclei. Photons transmit the electromagnetic force that acts between electrically charged particles, like electrons. The other particles in the table are also important, but for less evident reasons. For example, around 60 billion electron neutrinos stream through every square centimetre of your body every second. These neutrinos are made inside the Sun, as a by-product of the process…

the rules of the game

Like them or not, rules govern our lives. Some we make, and some we break. But zoom out, and there’s one set of rules that overrides them all. These are the rules of particle physics, and if we get to grips with them, we can understand what everything in the Universe is made from, and why everything behaves as it does. The basic rules are not complicated: each particle can hop around, and in doing so can emit or absorb other particles. For example, an electron can hop from one place to another, emitting or absorbing particles of light (photons) as it goes. Once we know the rules governing how electrons move around, we can understand the behaviour of atoms and molecules. There’s a nice analogy between particle physics and chess that…