Elementary particle

Everything is made of tiny bits.

Some bits are not made of anything else. We call these bits elementary particles. They are the smallest parts of all.

Some bits are made of even smaller things. These are called composite particles. A proton is a composite particle. It is made of tiny quarks.

There are many kinds of these tiny bits. Some help things stick together. Others help things move.

Scientists study these bits to learn about our world. It is amazing how much they make!

Everything in our world is made of tiny bits. Some bits are not made of anything else. We call these elementary particles. They are the smallest parts of all.

Scientists use a set of rules called the Standard Model to study them. This model lists seventeen different types of elementary particles. These are split into two main groups. The first group is called fermions. Fermions include things like electrons and quarks. The second group is called bosons. Bosons help carry forces between particles.

Quarks are very special. They are never found alone. Instead, they stick together to make bigger things. For example, two up quarks and one down quark make a proton. Protons and neutrons make up the center of an atom.

Some bosons also play big roles. Photons are bosons that carry light. The Higgs boson is a particle that helps give other particles mass. Scientists found the Higgs boson in 2012. It was found at a huge machine called the Large Hadron Collider. This machine helps us see how the smallest parts of our world work.

Everything in our world is made of tiny bits. Some of these bits are not made of anything else. We call these elementary particles. They are the most basic parts of nature.

Scientists use a set of rules called the Standard Model to study them. This model lists seventeen different types of elementary particles. These are split into two main groups. The first group is called fermions. Fermions include things like electrons and quarks. The second group is called bosons. Bosons help carry forces between particles. Together, these particles make up everything we see.

Particles work in very specific ways. All elementary particles are either fermions or bosons. Fermions follow rules called Fermi–Dirac statistics. Bosons follow different rules called Bose–Einstein statistics. You can tell them apart by something called spin. Fermions have a half-integer spin. Bosons have an integer spin. In the Standard Model, we treat these particles as tiny points. This helps scientists make predictions about how they act.

People have studied these tiny bits for a long time. Long ago, people thought atoms were the smallest thing. The word atom comes from a Greek word meaning uncuttable. For many years, people argued about if atoms were real. In 1905, Albert Einstein helped solve this mystery. He wrote a paper about how molecules move. Later, scientists found smaller parts inside the atom. They found the electron first. Then they found the proton in 1919. They found the photon in the 1920s. Finally, they found the neutron in 1932.

There are many different kinds of these particles. The twelve fermions are split into three generations. These include leptons like the electron and the muon. They also include six types of quarks. Quarks are very special because they are never found alone. They stay trapped in groups called hadrons. For example, two up quarks and one down quark make a proton. Protons and neutrons make up the center of an atom.

Some particles help the universe work through forces. Gluons carry the strong force to hold quarks together. Photons carry light through the electromagnetic force. There are also W and Z bosons for the weak force. One very famous particle is the Higgs boson. It helps give other particles their mass. Scientists looked for it for many years. On July 4, 2012, they finally found it. They used the Large Hadron Collider at CERN to see it.

An elementary particle is a subatomic particle that is not made of other particles. In the Standard Model of particle physics, these are the most fundamental building blocks of nature. While we often think of atoms as the smallest units of matter, atoms are actually composite particles. They are made of smaller parts like protons and neutrons, which are themselves made of elementary particles. The Standard Model identifies seventeen distinct elementary particles. These are divided into twelve fermions and five bosons. Because of different combinations of flavor, color, and antimatter, there are 61 total variations of these particles.

All elementary particles fall into one of two categories: fermions or bosons. Scientists distinguish these groups using quantum statistics. Fermions obey Fermi–Dirac statistics, while bosons obey Bose–Einstein statistics. You can also tell them apart by their spin, which is a fundamental property. Fermions have a half-integer spin. Bosons have an integer spin. In the Standard Model, physicists represent these particles as point particles to make mathematical predictions. This model is extremely successful, though it does not yet include gravitation.

The twelve fundamental fermions are organized into three distinct generations. Each generation contains four specific particles. The first group is the leptons, which includes the electron, the muon, and the tau. It also includes three types of neutrinos. Neutrinos are unique because they have no electric charge and no color charge. The second group consists of six quarks. Quarks are never found alone due to a process called confinement. They are always trapped inside larger particles called hadrons.

Quarks interact through a property called color charge. This is related to the strong interaction, not actual visual colors. There are three types of color: red, blue, and green. Quarks can combine to form color-neutral particles. For example, three quarks can form a baryon, such as a proton or a neutron. A quark and an antiquark can pair up to form a meson. Protons are made of two up quarks and one down quark. Neutrons are made of one up quark and two down quarks.

The history of discovering these particles is a journey from theory to measurement. For thousands of years, people believed atoms were indivisible. The word "atom" comes from the Greek word "atomos," meaning uncuttable. This idea changed in 1905 when Albert Einstein published a paper on Brownian motion. His work helped prove that molecules were real and not just mathematical illusions. Following this, scientists identified the electron, the proton in 1919, the photon in the 1920s, and the neutron in 1932.

Bosons play a different role by mediating the fundamental forces of the universe. There are four types of gauge bosons in the Standard Model. Gluons carry the strong interaction, which holds quarks together inside hadrons. Photons are massless particles that mediate the electromagnetic interaction. The W and Z bosons mediate the weak interaction, which is responsible for nuclear decay. For instance, a W− boson can convert a neutron into a proton. These four particles together form what is known as the electroweak interaction.

One of the most important particles is the Higgs boson. It is a scalar boson with a spin of zero. The Higgs boson is responsible for the intrinsic mass of other particles. This happens through a process called spontaneous symmetry breaking. This process also explains why the W and Z bosons are heavy while the photon remains massless. Scientists searched for the Higgs boson for many years. On July 4, 2012, researchers at the Large Hadron Collider announced they had likely detected it.

Understanding these particles helps us understand the composition of the entire universe. During Big Bang nucleosynthesis, the universe formed mostly from hydrogen and helium-4. Most of the visible mass in the universe comes from protons and neutrons. These are made of up and down quarks. While neutrinos are very numerous, they are so light that they do not contribute much to the total mass. Some theories, like supersymmetry, suggest there may be even more particles. These would include "sparticles," which are much heavier partners to the particles we know today.