Particle physics

Particle physics, also known as high-energy physics, is the study of the tiny building blocks that make up everything in the universe, and the forces that act between them. These building blocks are called fundamental particles, and they combine to form the matter we see all around us, like the atoms in our bodies and the stars in the sky.

The universe is made up of two main types of particles described in something called the Standard Model: fermions, which are the particles of matter, and bosons, which carry forces between particles. Ordinary matter, like the stuff we touch every day, is made from just the first generation of fermions. These include particles called up and down quarks, which come together to form protons and neutrons—the pieces that make up the nucleus of an atom—and electrons, which orbit the nucleus.

Quarks cannot exist alone but can combine to form particles called hadrons. The most familiar hadrons are protons and neutrons, which make up almost all the mass of ordinary objects. Other hadrons, called mesons, are very short-lived and are usually created when particles crash into each other at very high speeds, such as in cosmic rays or in special machines called particle accelerators. Every particle also has a matching antiparticle, like the positron, which is like an electron but with the opposite electric charge. These antiparticles could, in theory, form a kind of matter called antimatter.

Scientists study these particles using huge machines like the Large Hadron Collider and also think deeply about their role in the universe using theories and models. One of the most exciting discoveries in recent years was the detection of the Higgs boson, a particle that was predicted by theory many years before it was found in experiments. Understanding particles helps us learn about the very beginning of the universe and how everything came to be.

History

Main article: History of subatomic physics

The idea that everything is made of tiny building blocks called elementary particles goes back to ancient times. In the 1800s, a scientist named John Dalton discovered that each kind of material is made of one special type of particle, which we now call an atom. Later, scientists found that atoms themselves are made of even smaller parts, like the electron.

In the early 1900s, scientists made big discoveries about how atoms work. They found out that atoms could split apart, a process called nuclear fission, and that smaller particles could combine to form bigger ones, called nuclear fusion. These discoveries helped scientists understand more about the tiny particles that make up our world.

Standard Model

Main article: Standard Model

The Standard Model helps us understand the tiny building blocks that make up everything around us. It explains how small particles called quarks and others work together through forces like the strong, weak, and electromagnetic forces. These particles can combine to form the matter we see and touch.

In 2012, scientists found a new particle called the Higgs boson, which was predicted by the Standard Model. While this model fits most of what we’ve observed, scientists think there might be more to discover about these tiny particles and the forces that guide them.

Subatomic particles

Modern particle physics studies tiny particles that make up everything around us, like electrons, protons, and neutrons. These particles can also include things like photons, neutrinos, and muons, as well as many other unusual particles. All of these particles and how they interact can be explained by something called the Standard Model.

Particles can act like both tiny balls and like waves, depending on how we look at them. Some particles, called elementary particles, seem to be the simplest building blocks and cannot be broken down any further.

Main articles: Quark and Lepton

Ordinary matter is made from tiny building blocks called quarks and leptons. Quarks and leptons are known as fermions because they have a special kind of spin and follow certain rules. Quarks come in different types and have fractional electric charges, while leptons, like the electron, have whole-number charges.

Main article: Boson

There are also particles called bosons that carry forces between particles. For example, photons carry the force of electricity and magnetism, while other bosons carry forces that hold atoms together. The Higgs boson is special because it helps give mass to other particles.

Main articles: Antiparticle and Color charge

Every particle has a matching antiparticle. When a particle and its antiparticle meet, they can disappear and turn into other particles. Some particles, like photons, do not have antiparticles.

Main article: Composite particle

Larger particles, like protons and neutrons, are made from smaller particles called quarks. These larger particles are called hadrons. Scientists are also studying some unusual particles that might solve mysteries about the universe, like what makes up dark matter.

Main article: Composite particle

Experimental laboratories

Some of the biggest places where scientists study tiny particles are around the world. One is Brookhaven National Laboratory in New York, United States, where they crash heavy particles together. Another is CERN near Geneva, Switzerland, home to the Large Hadron Collider, which smashes particles at very high speeds.

Other important labs include DESY in Germany, Fermi National Accelerator Laboratory (Fermilab) in Illinois, United States, and KEK in Japan. These labs help scientists learn more about the tiny building blocks that make up everything around us.

Theory

Theoretical particle physics tries to create models and tools to help us understand experiments and predict future ones. Scientists work hard to better understand the Standard Model, which describes the basic building blocks of nature. They also explore ideas about what might exist beyond the Standard Model, such as new types of symmetry or extra dimensions.

Another big area of study is string theory, where scientists try to combine two big ideas in physics—quantum mechanics and general relativity—by thinking of tiny strings instead of points. This could help create a complete theory that explains everything.

Practical applications

The study of tiny particles has led to many useful inventions in everyday life. For example, machines called particle accelerators help doctors treat illnesses and make special materials that can carry electricity without losing energy. Important technologies like the World Wide Web and touchscreen devices were first created by scientists working with particles at a special lab called CERN. These discoveries show how learning about particles can help people in many different ways.

Future

Scientists are working on new experiments to learn more about particles. Big projects like the Future Circular Collider at CERN and the Particle Physics Project Prioritization Panel in the US aim to discover things beyond what we currently know. These efforts include plans for experiments such as the Deep Underground Neutrino Experiment to explore the mysterious particles called neutrinos.