How many elementary particles are there

Improve this answer. CuriousOne CuriousOne Still point taken. One should always keep an open mind. One can still consider atoms elementary for the purposes of chemistry and we will probably continue to consider quarks and electrons as elementary for sub-TeV physics purposes, so the definition is not just a matter of history, but also one of the hierarchy of models to describe reality in increasing level of detail.

Anna basically gave you the correct answer to that Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. Featured on Meta. Now live: A fully responsive profile. The empty space in the protons, neutrons, and the atom still remains.

So, where does mass come from? Learn more about untangling how quantum mechanics works. Everything is made of atoms, and everything has a mass. However, the atom is essentially empty space. Protons and neutrons have almost the same mass and are called nucleons, in general. If the mass is rounded up to , the electrons can be ignored. But the nucleons also have a considerable empty space inside. The gluons are massless, so each quark must have a mass equal to one-third of the nucleon, but they do not.

The speed of the quarks is close to the speed of light, which means they contain considerable kinetic energy. Quarks zoom around in the space of 10 m across, and keeping such a fast object in such a small place requires enormous forces, hence, creating massive potential energy. Learn more about untangling what quantum mechanics means. There is more in the atom: virtual particles of matter and antimatter that last only a moment.

They add to the complexity of the image, as they appear everywhere in the universe, from the deep space to the core of atoms. The final image of an object would be mainly energy held together by force fields in the protons and neutrons, nuclei, atoms, and molecules creating the object. This is explainable in the quantum realm.

Since normal matter does not contain these particles it may seem that they are an unnecessary complication. However during the first one to ten seconds of the universe following the Big Bang, they had a crucial role to play in establishing the structure of the universe in which we live — known as the Lepton Epoch.

The up and down quarks stick together to form the protons and neutrons which lie at the heart of every atom. There are six force particles in the standard model, which create the interactions between matter particles. They are divided into four fundamental forces : gravitational, electromagnetic, strong and weak forces. A photon is a particle of light and is responsible for electric and magnetic fields , created by the exchange of photons from one charged object to another.

The gluon produces the force responsible for holding quarks together to form protons and neutrons, and for holding those protons and neutrons together to form heavier nuclei. A sixth force particle, the graviton, is believed to be responsible for gravitation, but has not yet been observed. We also know of the existence of anti-matter.

This is a concept much beloved by science fiction writers, but it really does exist. Anti-matter particles have been frequently observed. For example, the positron the anti-particle of the electron is used in medicine to map our internal organs using positron emission tomography PET.

Famously when a particle meets its anti-particle they both annihilate each other and a burst of energy is produced. A PET scanner is used to detect this. Detailed studies of quarks and leptons at accelerator experiments will provide the clearest insight into these issues. Physicists have so far identified 57 species of elementary particles.

In particular, the Standard Model contains quarks and leptons, grouped into three families that differ only in their masses. Why the pattern of particles is repeated three times with enormous variations in mass but with other properties seemingly identical is an open question. Quantum physics has shown that three families are the minimum necessary to accommodate CP violation in the Standard Model. Such CP violation is necessary for matter to predominate over antimatter in the universe, but its effects observed so far are insufficient to explain this predominance.

The current program of experiments focuses on developing a detailed understanding of the existing patterns and searching for signs that the patterns of the three families are not identical. Even through the Tevatron was shut down, the CDF and DZero experiments at the Tevatron , which recorded collisions until September , continue to provide information on the top quark and check if its enormous mass gives it a special role in the particle world.