Higgs Boson and Other Subatomic Particles
Large Hadron Collider: Looking For The "God" Particle
The Higgs Boson has been in the news a lot recently, as physicists at the Large Hadron Collider or LHC at CERN (near Geneva) try to detect and study this illusive subatomic particle. I studied physics at the University of Oxford a few decades ago and had been fascinated by subatomic particles for years before that, but when someone recently asked me what all the fuss was about, concerning the Higgs Boson, I struggled to give a satisfactory answer, without the use of complex maths, so I decided to try to simplify the subject of sub-atomic particles and the physics required to understand or at least bluff your way through the subject.
What is a Higgs Boson (or for that matter any Boson) and why do scientists deep under the border of Switzerland and France collide lots of Hadrons (e.g. protons) into each other (at enormous cost)? Why is it sometimes referred to (some might say blasphemously) as the "God" particle?
4th July 2012: A particle 'consistent with the Higgs boson' has been detected today and Stephen Hawkin loses his $100 bet!
October 2013: Peter Higgs and Francois Englert awarded the Nobel Prize in Physics for their work in the theory of Higgs Boson
CERN: The Home of The Large Hadron Collider (LHC)
CERN and the Large Hadron Collider
Where is CERN? (just outside Geneva) - What is the LHC?
CERN and the enormous Large Hadron Collider lies deep underground under the border between France and Switzerland. The LHC is a 17-mile circular tunnel in which protons are accelerated in opposite directions to nearly the speed of light before colliding into each other. The two detectors, ATLAS and CMS analyze the debris emanating from the proton-proton collisions.
Subatomic Particles: Hadrons and Leptons
and how to detect them
We all know that (almost) everything is made up of atoms and they in turn are made up of protons, neutrons and electrons. And that electrons are indivisible "elementary" particles (probably) but protons and neutrons are themselves made up of smaller particles called quarks and there are other particles of various sizes and masses and each has an antiparticle. Many have been observed (although not in the conventional sense) by experiments such as those undertaken at CERN, but what is the Higgs Boson and why all of the media coverage?
Elementary particles and other subatomic particles are identified using particle accelerators or colliders (The Large Hadron Collider - LHC - at CERN is a huge underground circular tunnel 17 miles long). Charged particles, such as protons are accelerated up to almost light speed and collided into each other using powerful superconducting electromagnets. The energy released results in other particles being created whose mass, charge and interactions can be determined by the traces left in detectors mounted around the collider. You never see the particles themselves just traces left by their paths through the detectors. Their trajectory through magnetic fields determines the speed, mass and charge of the particles. The detectors used with the LHC are ATLAS (A Toroidal LHC ApparatuS), CMS (Compact Muon Solenoid), ALICE (A Large Ion Collider Experiment) and LHCb (Large Hadron Collider beauty)
There are a huge number of subatomic particles, far too many to get to intimately know all of them, so they are organised into families to aid understanding of their interactions and decays.
All matter particles are either Hadrons (affected by the strong force) or Leptons (unaffected by the strong force)
Protons and neutrons that can be found in the nucleus of all atoms are Hadrons and the electrons that surround them are Leptons.
Hadrons are made up of two or three quarks which are themselves bound together by particles called gluons.
Quarks come in six different varieties (or "flavors"): "Up", "Down", "Strange", "Charm", "bottom" and "Top". There are also six anti-quarks with opposite charge.
Collider - The Search for the World's Smallest Particles
What is a Boson?
Different Types of Subatomic Particle
Elementary particles are also divided into Fermions and Bosons as are composite particles depending on their constituents, although this describes their behaviour, rather than which family they belong to: A fermion is any particle that obeys Fermi-Dirac Statistics (and also the Pauli exclusion principle) whereas bosons obey Bose-Einstein statistics (and don't obey the Pauli exclusion principle) I shall come to that later.
Fermions are usually matter particles such as electrons (an elementary particle) and protons (a composite particle made up of quarks) and have half integer-spin and cannot occupy the same quantum state as another fermion - i.e. to occupy the same space they must have different properties (e.g. different spin directions - This is referred to as the Pauli exclusion principle)
Bosons have integer spin and can occupy the same point in space even with the same properties and are usually force carrying particles (forces between objects are transmitted by the transfer of virtual sub-atomic particles). One exception is pairs of electrons that join together at low temperatures in metals to form Cooper's Pair which has Bosonic behaviour which explains superconductivity at low temperatures.
The Standard Model of Elementary Particles (i.e. Particles that cannot be broken into smaller particles) includes a total of 24 different elementary fermions of two different types, quarks and leptons: 6 quarks and 6 leptons and their corresponding anti-particle.
The Quarks are:Up, Charm, Top - (all with spin=1/2 and charge= 2/3)Down, Strange and Bottom - (all with spin=1/2 and charge= -1/3)
The Leptons:Electron Neutrino, Muon Neutrino, Tau Neutrino - (all with spin=1/2 and charge=0)Electron, Muon and Tau - (all with spin=1/2 and charge= -1)
The four Bosons in the Standard Model all have a spin of 1 and are:photon - (force carrier of the electromagnetic force and light - zero mass)gluon - (the exchange particle that causes the Strong Force between quarks - zero mass)Z Boson - (responsible for the weak interaction)W Boson - (also responsible for the weak interaction)
Big Bang Theory
At last a comedy show about us Physicists
The Higgs Boson (or "God" Particle)
What is the Higgs Boson and Why is it Important?
Why is the Higgs Boson referred to as The God Particle?
The Higgs particle is a Boson: a short-lived force carrying particle that decays rapidly after being created in a high energy proton-proton collision. It cannot be observed directly, but the traces of the decay products may be detected. Evidence so far suggests the Higgs particle to be about 126 times the mass of a proton.
The reason the Higgs particle is of so much interest is that physicists love symmetry and the existence of a Higgs particle helps to explain the lack of symmetry in the universe: Some particles have mass whereas others do not and different particles are acted on by difference forces. The Strong Force, Weak Force, Electromagnetism and gravity. Each force is the result of the exchange of particles. Physicists want to unify these forces; to find a single relationship that describes them all. Electricity and magnetism have been unified since the times of Maxwell and Lorenz over 150 years ago and more recently relationships between electromagnetism and the weak force have been proposed (the electroweak force)
Peter Higgs proposed a mechanism for breaking the universe's initial symmetry, which requires the existence of a Higgs field which extends across the whole of space and sets the lowest energy state for a vacuum. A true vacuum would have a lowest energy state of zero, but a false vacuum would have a higher energy level. As Einstein postulated E=mc2 (energy = mass x speed of light squared) so that energy would exist as particles with mass e.g. the particles that result in the weak force. At very high energies the Higgs field value is blurred, but at lower temperatures it dictates a single value that results in mass existing for the exchange particles of the weak exchange, whereas photons (particles of light) remain massless. The Higgs field requires the existence of a Higgs particle and its ability to cause other particles to acquire mass resulted in the name "God Particle" (Hence, perhaps the media interest) Finding the Higgs particle does not prove or disprove the existence of a God.
Better explanation for the name:
Actually that explanation is probably complete rubbish and was invented after the Higgs Boson had already acquired it's unfortunate nickname.
Higgs is actually an atheist, and doesn't like the boson being called the "God particle". He believes this "might offend people who are religious". The nickname is attributed to Leon Lederman, the author of the book The God Particle: If the Universe Is the Answer, What Is the Question? - Lederman had intended to refer to the HIggs particle as the "goddamn particle" (goddam illusive), but Lederman's publisher insisted he change the title.
Peter Higgs and Francois Englert Won Nobel Prize in Physics
In October 2013 Peter Higgs (UK) and Francois Englert (Belgium) shared the Nobel Prize in Physics for their work in the Higgs Boson theory: In the 1960s they worked on a theory to explain why the existence of mass. The theory required the existence of a particle, the Higgs boson, which discovered in 2012 at the Large Hadron Collider at Cern, in Switzerland.