Particle Physics

Understanding fundamental particles and the Standard Model

Topics

What are neutrinos?

Neutrinos are nearly massless, chargeless particles that interact only weakly with matter. They're produced in nuclear reactions, including fusion in stars and radioactive decay. Billions pass through your body every second, but they rarely interact, earning them the nickname 'ghost particles.'

What are quarks?

Quarks are fundamental particles that make up protons and neutrons. There are six types (flavors) of quarks: up, down, charm, strange, top, and bottom. Quarks combine in groups of two or three to form hadrons, and they're never found alone due to color confinement.

What are subatomic particles?

Subatomic particles are particles smaller than atoms, including protons, neutrons, and electrons that make up atoms, as well as many other particles discovered in particle physics. They include quarks (which make up protons and neutrons), leptons (like electrons), and force-carrying particles.

What is an atom?

An atom is the smallest unit of an element that retains the element's properties. Atoms consist of a nucleus (containing protons and neutrons) surrounded by electrons. The number of protons determines the element, while electrons determine chemical behavior.

What is antimatter?

Antimatter is matter made of antiparticles—particles with opposite charge to normal particles. Antielectrons (positrons) have positive charge, antiprotons have negative charge. When matter and antimatter meet, they annihilate, converting to energy.

What is dark matter?

Dark matter is invisible matter that doesn't emit, absorb, or reflect light, detectable only through its gravitational effects. It makes up about 27% of the universe's mass-energy, far exceeding visible matter. Dark matter's nature is unknown, but it's essential for explaining galaxy rotation, cosmic structure, and gravitational lensing.

What is nuclear fission?

Nuclear fission is the process where a heavy atomic nucleus splits into two or more lighter nuclei, releasing energy and often neutrons. Fission occurs when a nucleus absorbs a neutron and becomes unstable, splitting apart. Fission powers nuclear reactors and atomic bombs.

What is nuclear fusion?

Nuclear fusion is the process where two light atomic nuclei combine to form a heavier nucleus, releasing enormous energy. Fusion powers the Sun and stars, where hydrogen nuclei fuse to form helium. Fusion requires extremely high temperatures and pressures to overcome the repulsive force between positively charged nuclei.

What is the Higgs boson?

The Higgs boson is a fundamental particle discovered in 2012 that is associated with the Higgs field, which gives other particles mass. The Higgs field fills all space, and particles interact with it to acquire mass, explaining why some particles are heavy while others are light.

What is the standard model?

The Standard Model is the theory describing all known fundamental particles and three of the four fundamental forces (electromagnetic, weak, and strong). It organizes particles into quarks, leptons, and force carriers, and has been extremely successful in predicting and explaining particle behavior.