Density and dense usually refer to a measure of how much of some entity is within a fixed amount of space. Types of density include:
Physics
Density of mass
- Density, mass per unit volume
- Bulk density, mass of a particulate solid or powder divided by the volume it occupies
- Particle density (packed density) or true density, density of the particles that make up a particulate solid or a powder
- Neutral density, mass density of seawater
- Area density or surface density, mass over a (two-dimensional) area
- Linear density, mass over a (one-dimensional) line
- Relative density or specific gravity, a measure of density in comparison to the density of something else
- Vapour density, a relative density used for gases
Densities of other entities
- Mass-specific quantity, the quotient of a physical quantity and mass
- Specific energy, energy per unit mass
- Volume-specific quantity, the quotient of a physical quantity and volume
- Charge density, the electric charge per volume
- Energy density, potential energy per unit volume
- Force density, force per unit volume
- Power density, power per unit volume
- Particle density (particle count), number of particles per unit volume
- Area-specific quantity, the quotient of a physical quantity and area
- Current density, the ratio of electric current to area
- Surface power density, power per unit area
Other:
- Number density, number of particles per unit volume, area, or length
- Optical density, the absorbance of a material
- Densitometry, measuring the optical density of photographic paper, photographic film and x-ray film
Mathematics
Probability and measure theory
- Probability density function, a function which maps probabilities across the real line and whose integral is 1
- Density estimation is the construction of an estimate of a probability density function
- Kernel density estimation, used in statistics to estimate a probability density function of a random variable
- Lebesgue's density theorem
Number theory
- Schnirelmann density
- Natural density (also called asymptotic density)
- Dirichlet density
Geometry
- Packing density
- Density (polytope)
- Density on a manifold
- Tensor density in differential geometry
Topology
- Dense set and nowhere dense set
- Dense-in-itself is a set that contains no isolated points
Other fields
- Density (graph theory), the fraction of possible edges that exist in a graph
- Dense order in order theory
- A coinitial subset in the mathematical theory of forcing, in set theory
- Dense submodule in abstract algebra
Other scientific fields
- Population density, population per unit land area
- Urban density, in urban planning and urban design
- Areal density (computer storage), bits (how computers store information) over an amount of area or volume
- Nutrient density, the proportion of any array of a single nutrient or nutritional factor, or of numerous nutrients in foods, often ordered by different scalar indices
Culture and arts
- Stupidity, a stupid person is sometimes referred to as being "dense"
- Dense (film), a 2004 film
- Density 21.5 – a piece of music for solo flute written by Edgard Varèse