GLOBAL KNOWLEDGE ARK

Reference library

Foundations

Explore concepts, laws, equations and methods, with clear explanations of their use and sources. Choose an area of study or find a specific entry.

More filters

Reference entries

Showing 301–330 of 1709 reference entries

BiologyDevelopment and cell differentiation

Regulated cell states, division and spatial organization produce multicellular form.

ModelEarth & cosmosMinerals, structure and diagnostic properties

Mineral identification combines structural and physical evidence.

MethodEarth & cosmosRadiometric ages and sample history

Isotopic measurements estimate an age only with a suitable geological model.

MethodEarth & cosmosSeismic constraints on Earth's interior

Wave travel, refraction and transmission constrain an interior model.

MethodEarth & cosmosThe geodynamo model

Fluid motion in the outer core maintains much of Earth's magnetic field.

ModelEarth & cosmosWater budgets and storage change

A defined area's water storage changes with total inflow and outflow.

ModelEarth & cosmosDarcy flux and hydraulic conductivity

Groundwater flow is often approximately linear in hydraulic-head gradient.

ApproximationEarth & cosmosOcean circulation and overturning

Wind, buoyancy changes and mixing contribute to ocean transport.

ModelEarth & cosmosGlobal atmospheric circulation

Unequal heating and rotation organize broad circulation patterns.

ModelEarth & cosmosClimate forcing and energy-budget perturbations

External changes can disturb climate's radiation budget.

DefinitionEarth & cosmosClimate feedback mechanisms

Climate responses can amplify or damp a change.

ModelEarth & cosmosClimate detection and attribution methods

Attribution compares observed changes with plausible drivers and variability.

MethodEarth & cosmosStellar evolution and fuel stages

Stellar structure changes as core fuel and conditions change.

ModelEarth & cosmosWhite dwarfs, neutron stars and stellar black holes

Different evolutionary outcomes leave different compact remnants.

ModelEarth & cosmosAnnual stellar parallax and distance

Changing observing position permits geometric distance inference.

MethodEarth & cosmosCosmological redshift and distance inference

Spectral stretching carries expansion information but is not one universal distance ruler.

MethodEarth & cosmosGalactic rotation and inferred mass

Measured motions constrain the gravitational mass distribution.

MethodEarth & cosmosPlanetary formation in young-star disks

Disk observations and competing growth mechanisms inform planet-formation models.

ModelEarth & cosmosCosmological parameters inferred from the CMB

CMB statistics constrain parameters within a chosen cosmological model.

MethodEarth & cosmosGravitational evidence for dark matter

Motions and lensing constrain mass beyond that accounted for by luminous material.

Empirical findingEarth & cosmosWhat constitutes dark matter?

Gravitational evidence does not yet settle the unseen component's physical identity.

Open questionEarth & cosmosWhat explains accelerated cosmic expansion?

Expansion evidence motivates competing physical descriptions with unresolved origin.

Open questionMathematics & logicIntermediate values and compact-domain extrema

A continuous real function on a closed bounded interval attains a maximum and minimum and takes every value between its endpoint values.

Mathematical statementMathematics & logicProduct, quotient and chain rules

Differentiable real functions satisfy (fg)′=f′g+fg′ and (g∘f)′=(g′∘f)f′.

Mathematical statementMathematics & logicMean value theorem

If f is continuous on [a,b] and differentiable on (a,b), a<b, some c∈(a,b) satisfies f′(c)=(f(b)−f(a))/(b−a).

Mathematical statementMathematics & logicDarboux intermediate-value property of derivatives

For f differentiable throughout an open real interval, its derivative takes every value strictly between f′(a) and f′(b) at some c∈(a,b), whenever a<b are points of that interval.

Mathematical statementMathematics & logicSubstitution in a definite integral

For g of class C¹ on [a,b] and f continuous on an interval containing g([a,b]), ∫ₐᵇ f(g(x))g′(x)dx=∫g(a)ᵍ(b)f(u)du.

MethodMathematics & logicIntegration by parts

For u,v of class C¹ on [a,b], ∫ₐᵇuv′dx=[uv]ₐᵇ−∫ₐᵇu′v dx.

MethodMathematics & logicDarboux sums and Riemann integrability

For bounded real f on [a,b], lower and upper Darboux sums use each subinterval's infimum and supremum.

Mathematical statementMathematics & logicContinuity and the Riemann integrability criterion

A bounded real function on [a,b] is Riemann integrable exactly when its discontinuity set has Lebesgue measure zero.

Mathematical statement
Empirical findingSource checked

Gravitational evidence for dark matter

Earth & cosmos

Motions and lensing constrain mass beyond that accounted for by luminous material.

Key knowledge

Galaxy and cluster dynamics and gravitational lensing indicate mass distributions that are not accounted for by observed luminous material under standard gravitational modelling. In colliding clusters, comparisons of lensing-derived mass with X-ray-emitting gas provide a further spatial test of the mass interpretation.

Conditions and scope

  • Lensing infers mass through a model; coloured composite images are not direct photographs of dark particles.
  • The evidence constrains a gravitational component and does not itself identify its microscopic composition.
Sources · 1

References

Sources retain their recorded scope. A source link alone does not establish verification of every statement.

  1. Dark Matter — Discovering and Studying Dark MatterChelsea Gohd — NASA Jet Propulsion LaboratoryTeaching resourcescience.nasa.govRead source

Evidence and review

NASA's source-documented dynamical and colliding-cluster lensing/gas comparisons.

2026-10-10 · Checked observation versus mass interpretation; no new lensing measurement or particle discovery claimed.

Related reference entries

Explore relationships within this area of study and its connections to other areas.

Showing 1–5 of 5 relationships

Scientific relationships · 5 / 5

The relationship type describes the connection. Its linked statements, sources and conditions define the scope.

  1. Related to
    Relationship sources · 1

    Linked statements

    • Galaxy and cluster dynamics and gravitational lensing indicate mass distributions that are not accounted for by observed luminous material under standard gravitational modelling. In colliding clusters, comparisons of lensing-derived mass with X-ray-emitting gas provide a further spatial test of the mass interpretation.

    Galactic and cluster motions are among the documented gravitational evidence.

  2. Related to
    Relationship sources · 1

    Linked statements

    • The physical composition of the dominant dark-matter component remains unresolved. Candidate descriptions must account for gravitational observations and structure formation while surviving other observational and experimental constraints. Distinguishing candidates requires evidence beyond a successful gravitational mass fit.

    The unresolved composition question is motivated by gravitational and structure observations.

  3. Related to
    Relationship sources · 1

    Linked statements

    • A thin gravitational lens relates a source's unlensed angular position to observed image positions through a mass-dependent deflection. Nonlinearity can produce multiple images. Lens-to-source and observer distances are angular-diameter distances; cosmological lens–source distance is not generally their simple difference.

    Lensing supplies mass evidence independently of emitted light.

  4. Related to
    Relationship sources · 1

    Linked statements

    • A point mass in the weak-field geometric-optics limit deflects light by magnitude α̂=4GM/(c²b). For a single thin lens, θ_E²=4GMD_ls/(c²D_lD_s). An ideal point source in perfect source–lens alignment produces a ring with this angular radius in the bounded point-mass model; interpreting observed images requires a lens and distance model.

    Lensing constrains gravity-producing mass independently of luminosity.

  5. Related to
    Relationship sources · 1

    Linked statements

    • Gravitational evidence constrains additional matter or modified gravitational descriptions under declared assumptions; it does not name a particle. Candidate production and interactions face distinct cosmological, astrophysical and laboratory constraints, so failure of one search does not eliminate every dark-matter model.

    Conceptual association supported by the recorded research scope; this relation does not assert a proven derivation or mandatory prerequisite.

Entry detailsPermanent link to this entry ↗
Record identity
cosmos-dark-matter-evidence
Revision
university-reference.1
Structured reference record
University reference