Matter

In physical science, matter is anything that has mass and takes up space by having volume. All objects we can touch are made of tiny building blocks called atoms. Atoms are made of even smaller parts known as subatomic particles. Matter can be found in many forms, such as solid, liquid, and gas. For example, water can be ice, liquid water, or gaseous steam.

Hydrogen in its plasma state is the most abundant ordinary matter in the universe.

Atoms have a central part called a nucleus made of protons and neutrons. Around the nucleus is a "cloud" of moving electrons.

People have wondered about matter for a very long time. The idea that matter is made of tiny pieces appeared in both ancient Greece and ancient India. Early thinkers such as the Indian philosopher Kaṇāda and the Greek philosophers Leucippus and Democritus suggested this idea.

Related concepts

Comparison with mass

Matter is anything that takes up space and has weight. Long ago, people used "matter" to mean anything you could touch or see.

In science, mass is a property of matter. Scientists talk about mass in different ways, like rest mass, inertial mass, and relativistic mass. Tiny parts of matter, called particles, can act like small balls and like waves at the same time. This is called wave-particle duality.

Definition

Based on atoms

Matter is made of tiny building blocks called atoms. These atoms are the little pieces that make up everything around us, like the molecules in deoxyribonucleic acid (DNA). This idea of matter can also include things like plasmas and electrolytes, which are special types of gases and liquids.

Based on protons, neutrons and electrons

Matter can also be described as being made of smaller parts called protons, neutrons, and electrons. These tiny parts come together to form atoms and molecules. This way of looking at matter includes more than just atoms, like the beams of electrons in old cathode ray tube televisions.

Based on quarks and leptons

Matter is also made of even smaller parts called quarks and leptons. Quarks and leptons combine to form atoms and molecules. This means that matter can be described as anything made of these tiny building blocks.

Based on elementary fermions (mass, volume, and space)

A simple way to think about matter is that it is anything that has mass and takes up space, like a car. This idea goes back a long time, and scientists now understand that what makes matter take up space is related to how these tiny parts behave.

Structure

In particle physics, fermions are tiny parts of matter that follow special rules. Fermions can be simple, like the electron, or made of smaller parts, like the proton and neutron. The Standard Model describes two main types of simple fermions: quarks and leptons.

Quarks are heavy particles with a special kind of charge. They are part of the building blocks of larger particles.

Baryonic matter is the part of the universe made of particles called baryons, which include protons and neutrons found in atoms. This type of matter is different from other parts of the universe like dark energy or black holes.

Leptons are another type of particle that have a special kind of charge but do not act the same way in strong forces. They are affected by gravity.

Quark properties
name	symbol	spin	electric charge (e)	mass (MeV/c²)	mass comparable to	antiparticle	antiparticle symbol
up-type quarks
up	u	1⁄2	+2⁄3	1.5 to 3.3	~5 electrons	antiup	u
charm	c	1⁄2	+2⁄3	1160 to 1340	~1 proton	anticharm	c
top	t	1⁄2	+2⁄3	169,100 to 173,300	~180 protons or ~1 tungsten atom	antitop	t
down-type quarks
down	d	1⁄2	−1⁄3	3.5 to 6.0	~10 electrons	antidown	d
strange	s	1⁄2	−1⁄3	70 to 130	~200 electrons	antistrange	s
bottom	b	1⁄2	−1⁄3	4130 to 4370	~5 protons	antibottom	b

Lepton properties
name	symbol	spin	electric charge (e)	mass (MeV/c²)	mass comparable to	antiparticle	antiparticle symbol
charged leptons
electron	e⁻	1⁄2	−1	0.5110	1 electron	antielectron	e⁺
muon	μ⁻	1⁄2	−1	105.7	~200 electrons	antimuon	μ⁺
tau	τ⁻	1⁄2	−1	1,777	~2 protons	antitau	τ⁺
neutrinos
electron neutrino	ν _e	1⁄2	0			electron antineutrino	ν _e
muon neutrino	ν _μ	1⁄2	0			muon antineutrino	ν _μ
tau neutrino	ν _τ	1⁄2	0			tau antineutrino	ν _τ

Phases

Main article: Phase (matter)

Phase diagram for a typical substance at a fixed volume

See also: Phase diagram and State of matter

Matter can be in different forms, called phases. These depend on things like pressure, temperature, and volume. Each phase has its own special properties. The most common phases are solids, liquids, and gases. There are also unusual phases like plasmas and superfluids. When conditions change, matter can shift from one phase to another. These changes are called phase transitions.

Antimatter

Main article: Antimatter

Antimatter is made from special particles called antiparticles that are different from the particles in regular matter. When a particle and its antiparticle meet, they disappear in a flash of energy, often turning into high-energy light called gamma rays or other particles. This happens because of a rule in physics: E = mc².

We don’t find antimatter naturally on Earth except in tiny amounts made by radioactive decay, lightning, or cosmic rays. This is because any antimatter that appears would quickly meet regular matter and disappear. Scientists can create small amounts of antimatter, like antihydrogen, but only enough to study its basic properties.

One of the big questions in science is why the universe seems to be made almost entirely of regular matter and not antimatter. In the early universe, matter and antimatter were thought to be equal, so scientists are still trying to understand what caused this difference.

Conservation

In physics, matter is made of special building blocks. These blocks can come together or break apart, but the total amount of matter stays the same. When a baryon is created, an antibaryon is also created, keeping the balance. Even though these pieces can change, the overall amount of matter doesn't disappear or appear out of nowhere.

This idea helps us understand how matter behaves in big reactions, like in nuclear bombs, where tiny bits of matter change form but aren't destroyed. The total amount of matter stays the same, even if it looks different.

Dark

Main articles: Dark matter, Lambda-CDM model, and WIMPs

Most of the universe is made of things we cannot see. There are two of these: dark matter and dark energy.

Dark matter is material we cannot see because it does not give off or reflect light. We know it is there because of how it moves stars and galaxies.

Dark energy is a force that makes the universe grow bigger faster. We do not fully understand what it is, but it seems to come from space itself.

Exotic

Main article: Exotic matter

Exotic matter is an idea from particle physics. It might include things like dark matter and dark energy. It also talks about materials that could have unusual properties, such as negative mass.

Historical and philosophical study

The idea of what matter is has changed a lot over time as we learned more about the tiny parts that make up everything. Today, we think of matter as anything that has mass and takes up space. This includes all the things we can touch, like books, trees, and even the air we breathe.

Long ago, people had different ideas about matter. Some thought everything was made of just a few basic things, like water, air, or fire. Others believed that everything was made of tiny, unchanging particles called atoms. These early ideas helped shape how we think about the world today. Later scientists built on these thoughts, leading to our modern understanding of atoms and the even smaller parts inside them.