The Particle Adventure | Unsolved Mysteries

Eternal questions The search for the fundamental The atom Is the atom fundamental? Is the nucleus fundamental? Are protons and neutrons
fundamental? The modern atom model The scale of the atom What are we looking for? The standard model The standard model quiz

Quarks and leptons Matter & antimatter What is antimatter? Quarks The naming of quarks Hadrons, baryons and mesons Leptons Lepton decays Lepton type conservation Lepton decay quiz Neutrinos Quiz - What particles are made of

The four interactions How does matter interact? The unseen effect Electromagnetism Residual EM force What about the nucleus? Strong Color charge Quark confinement Quarks emit gluons Residual strong force Weak Electroweak Gravity Interaction summary Quantum mechanics The Pauli Exclusion Principle Fermions and bosons A lot to remember

What is decay? Radioactivity Radioactive particles Confusion about decays A look into the nucleus If it can happen, it will Half life Missing mass Particle decay mediators Virtual particles Different interactions Annhiliations Bubble chamber and decays Neutron beta decays Electron / positron annhiliation Top production

Beyond the standard model The standard model as a theory Three generations What about masses? Grand Unified Theory Forces and the Grand Unified Theory Supersymmetry String theory Extra dimensions Dark Matter

Testing a theory Searching for the atom's structure Rutherford's result Rutherford's analysis How physicists experiment Deflected probe

Detecting the world A better microscope Wavelength - The cave Wavelength - The moral Wavelength and resolution explained The physicists tool: The accelerator Waves and particles The world's meterstick Mass and energy Energy-mass conversion

Accelerators How to obtain particles to accelerate Accelerating particles Accelerating particles: Animation Accelerator design Fixed target experiments Colliding beam experiment A linear or circular accelerator What makes particles go in a circle? Advantages of accelerator design Major accelerators The event Detectors Detector shapes

Modern detectors Typical detector components Measuring charge and momentum Detector cross section Quiz - Particle tracks The computer reconstruction A quark/gluon event The end

Unsolved Mysteries - Three generations

There are three "sets" of quark pairs and lepton pairs. Each "set" of these particles is called a generation, or family. The up/down quarks are first generation quarks, while the electron/electron neutrino leptons are first generation leptons.

Why are there exactly three generations of matter?

The generations increase in mass and higher generation particles tend to decay into lower generation particles. In the every-day world we observe only the first-generation particles (electrons and up/down quarks). We do not know why the natural world "needs" the two other generations, and we do not know why there are exactly three generations in total.