gives the value of a specified property.
gives the value of a list of properties.
Sample Entity Classes
AbbreviationCode abbreviation code AlternateNames alternate names ASCIIDescription ASCII description Classes classes ConjecturedValueAssociation conjectured value association ConjecturedValues conjectured values Description description EntityClasses entity classes EqualMagnitudeConstants equal‐magnitude constants EquivalentForms equivalent forms ExternalLink external link LevyLeblondClass Lévy‐Leblond class Name name PrimarySource primary source Quantity quantity RelativeUncertainty relative uncertainty SeriesExpansionValueAssociation series expansion value association SeriesExpansionValues series expansion values StandardUncertainty standard uncertainty StandardYear standard year Symbol symbol Value value ValueAssociation value association Values values Variants variants VariantTable variant table
- "PhysicalConstant" entities include constants from physics, chemistry and astronomy whose values are characteristic of the universe, correspond to characteristics of the solar system, etc.
- "PhysicalConstant" entity classes include classifications based on physical quantity, standards authority and exactness of definition.
- Some properties are available for the "PhysicalConstant" entity type as a whole and can be given using the form EntityValue["PhysicalConstant",property]. Such properties include:
"Properties" the list of available properties "PropertyCanonicalNames" the standard names of available properties "SampleEntities" a sample list of available entities (typically of length 10) "SampleEntityClasses" a sample list of available entity classes (typically of length 10) "EntityCount" number of entities available "Entities" the list of available entities "EntityCanonicalNames" the standard names of available entities "EntityClasses" the list of available entity classes "EntityClassCanonicalNames" the standard names of available entity classes "PropertyClasses" the list of available property classes "PropertyClassCanonicalNames" the standard names of available property classes "PropertyCount" number of properties available
- The following annotations can be used in the third argument of EntityValue["PhysicalConstant",property,annotation]:
"Source" source information for the property "Date" the date associated with the entity-property value (if any) "EntityAssociation" an association of entities and entity-property values "PropertyAssociation" an association of properties and entity-property values "EntityPropertyAssociation" an association in which the specified entities are keys, and values are a nested association of properties and entity-property values "PropertyEntityAssociation" an association in which the specified properties are keys, and values are a nested association of entities and entity-property values "Dataset" a dataset in which the specified entities are keys, and values are an association of property names and entity-property values
- The following annotations can be used in the second argument of EntityValue[property,annotation]:
"Qualifiers" the list of possible qualifiers for the property "QualifierValues" the list of possible values that can be given to each qualifier "DefaultQualifierValues" the list of default values for the property's qualifiers "Description" a brief textual description of the property "Definition" a detailed textual definition of the property "PhysicalQuantity" the physical quantity associated with the entity-property value "Unit" the unit associated with the entity-property value
- A qualifier value of Automatic indicates that an applicable format of values can be used; e.g. for the "Date" qualifier, this includes a proper date or date span.
Examplesopen allclose all
Basic Examples (4)
Neat Examples (1)
Visualize the characteristic length and mass scales for various objects (cf. https://arxiv.org/pdf/1910.00481):
Plot the points in length-mass space. where the red line marks the quantum mechanical boundary, the green line marks the black hole boundary, the light blue line marks the boundary from the cosmological density, and the point of intersection of the black hole and cosmological lines is termed the cosmological-quantum (CQ) point: