The concept of matter is one of the most important foundations of our modern understanding of the world around us. Matter is traditionally considered a chemistry and physics term, originally defined as any object or substance that was made up of atoms. The definition of matter has expanded as the scientific understanding of the world around us has grown. An understanding of matter in all its forms, including exotic matter, is an important facet of the study of chemistry, and science in general, particularly in terms of our surrounding environment.
The most basic definition of matter is along the lines of: whatever physical objects are made out of. The matter that makes up a pillow would be the stuffing inside of it. The matter that makes up a book is the paper of the pages, and so on. Scientifically, matter has been defined more specifically as anything that is made up of atoms, and therefore anything that has a mass, mass being defined as the property of a physical object that determines how it reacts to gravity. Objects with larger mass have a stronger gravitational pull, while objects with a smaller mass exert a weaker gravitational force on other objects. Atoms are the fundamental units that make up matter. Atoms can be broken down into several parts known as subatomic particles, including the central nucleus, negatively charged particles called electrons, positively charged particles called protons, and neutrally charged particles called neutrons. Almost everything you can think of, more particularly anything that has mass, is composed of atoms on a structural level.
Categories of Matter
Matter can take a variety of forms, and as a result it is often categorized into four basic groups, commonly referred to as states of matter. The four states of matter are solid, liquid, gas, and plasma, and each state has a particular set of characteristics that distinguish it from the other three. Solids are objects in which particles, including atoms, are packed so closely together, with such rigidity, that those particles cannot move on their own. Solids are characterized by their definite shape and definite volume, which are stable and cannot be changed without the use of extreme pressure or force. A solid that changes its shape or volume is usually doing so when it is forcibly broken apart. Liquids, on the other hand, do not have a definite shape. They adjust to the shape of the container in which they are held. The molecules in liquids are densely packed as they are in solids, but the molecules are not arranged in a particular or rigid order. It is very difficult to compress a liquid, and though liquid’s shape is variable, its volume remains the same unless the temperature or pressure exerted on the liquid is altered. For example, liquid water’s volume and shape changes when extreme temperatures turn it into a solid, ice, or a gas, water vapor. These changes are referred to as phase transitions, because a substance is transitioning from one matter phase to another. Gases consist of molecules that are very far apart from one another. Unlike liquids, gases have no definite volume, and unlike solids, they have no definite shape. They can fill a container like liquids, but they will expand to fill the entire container, which liquids will not. The fourth fundamental state of matter, and also the most abundant in the universe is plasma. Plasma is created when gases are ionized. Ionization is the process by which an atom or a molecule’s number of electrons changes, resulting in that atom acquiring a negative or positive charge. The most common example of plasma creation due to ionization is the ionization of gases that takes place inside of stars. Gases, most often hydrogen and helium, are heated and ionized, creating plasma, matter that is full of positively and negatively charged molecules. These charged molecules usually balance each other out, so plasma tends to have an overall neutral charge. Plasma can conduct electricity very well, and can only be created at very high temperatures, such as the temperature within burning stars.
As scientific observation of matter has further developed and advanced, many more categories have been established in terms of states in which matter can exist. Many of these fall under the umbrella of exotic matter.
Exotic matter is defined as matter that has exotic properties, or characteristics that deviate from the accepted physical properties of matter. Some additional kinds of exotic matter have normal physical properties, but are not commonly encountered in nature. Types of exotic matter include both real and hypothetical objects or molecules, though most exotic matter remains hypothetical, unobserved and unproven as of yet in our universe.
One hypothetical example of exotic matter is a particle with a negative mass. As of now, modern scientists have never discovered a particle with negative mass, but they have speculated and theorized as to the properties that such a particle would possess. A particle with negative mass would behave in the opposite way that most particles behave when it comes to positive and negative attraction. Typical particles with negative charges are attracted to particles with positive charges, and repelled from other particles that share their negative charge. If one of these hypothetical particles were negatively charged, it would repel from positively charged particles, and be attracted to negatively charged particles. Similarly, the existence of wormholes, or tunnels that connect two separate locations in space-time, would be made far more plausible if these negative-mass particles could reach a level of stability to form one.
Tachyons are another hypothetical example of exotic matter. A tachyon is a particle with an imaginary mass. The existence of tachyons is an interesting possibility because, according to Einstein’s E=mc^2 equation, these particles would be able to travel faster than the speed of light. Since time and space are interconnected, and theoretically outrunning the speed of light could mean moving forward or backward in time, a particle such as a tachyon could have the ability to time-travel.
Though technically hypothetical, dark matter is a kind of exotic matter that scientists believe can explain some aspects of the behavior of our universe. Astronomers often observe effects of matter in the universe in areas where matter is not visibly present. Specifically, objects in the universe are often seen reacting to the gravitational pull of unseen matter. A popular theory suggests that these effects are caused by dark matter, a kind of matter that does not emit light or electromagnetic radiation, making it invisible to observers. Since astronomers have been able to determine the approximate size of the universe, it has been calculated that around 85% of the matter in the universe is this unidentifiable dark matter.
The Bose-Einstein condensate was, until recently, a hypothetical state of matter predicted by Albert Einstein and Indian physicist Satyenda Nath Bose, and commonly referred to as the fifth state of matter. This state of matter is characterized by particles that stop moving and behaving independently, collapsing into a collective state. This change is the result of very cold temperatures, especially temperatures that approach absolute zero.
Now that you’ve developed a sense of what matter is, how it is categorized, and what constitutes exotic matter, you can move forward with your study of matter, chemistry, and other categories of science, such as physics or biology. The study of science, particularly in terms of matter and its properties, can lead to a better understanding of the world around us, how it is organized, and how different substances interact within it.