The universe is filled with a staggering variety of phenomena, yet much of what we perceive can be categorized into two fundamental concepts: matter and everything else. Matter constitutes all the physical “stuff” that makes up the stars, planets, and every object we can touch or see. This tangible component is defined by a specific set of properties. The non-matter category encompasses the forces, dimensions, and capacities that govern how the physical world behaves and changes.
What Exactly is Matter
Matter is formally defined by two distinct physical properties: it must possess mass and it must occupy volume. Mass is a measure of an object’s resistance to acceleration, often called inertia. Volume is the three-dimensional space that substance takes up, preventing other matter from occupying the same location.
All ordinary matter is built from atoms, which are themselves composed of subatomic particles like protons, neutrons, and electrons. These particles fit the definition of matter because they possess a measurable rest mass and occupy a volume due to quantum mechanical effects. Establishing this boundary of mass and volume allows us to classify everything else—from light to gravity—as non-material.
The Realm of Energy
Energy represents the largest and most familiar category of non-matter, fundamentally defined as the capacity to do work or cause change in a system. Unlike matter, energy does not have a rest mass and it does not take up a specific volume. This is why forms like light and heat are not considered physical substances.
One of the most common forms is electromagnetic radiation, which includes visible light, radio waves, and X-rays. This radiation is carried by particles called photons, which are massless and always travel at the speed of light. Because photons lack rest mass, they fail the primary test for being considered matter, illustrating that light is a transfer of energy.
Thermal energy, or heat, is another ubiquitous form of non-matter. It represents the collective kinetic energy of the particles within a substance. While the particles themselves are matter, the heat is the energy being transferred due to their random motion. Similarly, sound is a form of energy that requires a material medium to travel, but the sound wave itself is merely the transfer of mechanical vibration, not a mass-possessing object.
Forces and Fields
The four fundamental interactions of the universe—gravity, electromagnetism, the strong nuclear force, and the weak nuclear force—are non-material. These forces are descriptions of how different particles and objects interact with one another. Each force is associated with a field, which is a region of influence extending through space.
Gravity is described by modern physics as a consequence of mass and energy curving the fabric of spacetime. The gravitational field is the distortion itself, acting as an influence that dictates the path objects will follow. Electromagnetism is similarly described by electric and magnetic fields, which are regions that exert influence on charged particles.
The electromagnetic interaction is mediated by the exchange of photons. The strong and weak nuclear forces, which operate only at the subatomic level, are mediated by gluons and W and Z bosons, respectively. These fields and the interactions they represent are considered non-matter because they are properties of space or particle exchanges, not substances with mass and volume.
Abstract Scientific Concepts
Beyond energy and forces, there are several foundational concepts in science that are non-material because they are best understood as dimensions, measurements, or properties.
Space
Space itself is considered the three-dimensional extent in which objects have relative position and direction. It is the stage upon which matter and energy operate, but it is not a substance that can be collected or measured in terms of mass.
Time
Time is the dimension that allows events to be ordered from the past through the present into the future. Time is a component of the spacetime continuum, but it is a measurement of duration and change, not a physical entity with volume. The measurement itself has no mass or volume.
Information
Information is an abstract concept that requires matter or energy to be stored or transmitted. Information is a pattern or a specific arrangement of states. While the physical storage medium, like the hard drive or the chemical bases of DNA, is matter, the meaning or content of the information is non-physical.