SI second
E116185
The SI second is the base unit of time in the International System of Units, precisely defined by a fixed number of periods of radiation corresponding to a specific transition in the cesium-133 atom.
All labels observed (2)
How this entity was disambiguated
This entity first appeared as the object of triple T982976 — resolving that mention is where its identity was fixed. The disambiguator weighed these candidate entities and picked the highlighted one (or “None”, minting a new entity). This is how homonymy is resolved: the same surface form can point to different entities.
NED1
Entity disambiguation (via context triple)
gpt-5-mini-2025-08-07
Target entity: SI second Context triple: [International Atomic Time, definedBy, SI second]
-
A.
SI
SI is the abbreviation for Skeptical Inquirer, a magazine devoted to scientific skepticism, critical thinking, and the investigation of extraordinary claims.
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B.
SiR
SiR is an American R&B singer, songwriter, and producer known for his smooth, soulful sound and work with Top Dawg Entertainment.
-
C.
.si
.si is the country code top-level domain (ccTLD) assigned to websites associated with Slovenia.
-
D.
ISA
ISA (Industry Standard Architecture) is an early computer bus standard used in IBM PCs and compatible systems to connect expansion cards and peripherals to the motherboard.
-
E.
ISA
ISA is the acronym for the International Seabed Authority, the intergovernmental organization responsible for regulating mineral-related activities in the international seabed area beyond national jurisdiction.
- F. None of above. chosen
- G. Unsure - the case is ambiguous/there is not enough information to decide.
NED2
Entity disambiguation (via description)
gpt-5-mini-2025-08-07
Target entity: SI second Target entity description: The SI second is the base unit of time in the International System of Units, precisely defined by a fixed number of periods of radiation corresponding to a specific transition in the cesium-133 atom.
-
A.
SI
SI is the abbreviation for Skeptical Inquirer, a magazine devoted to scientific skepticism, critical thinking, and the investigation of extraordinary claims.
-
B.
SiR
SiR is an American R&B singer, songwriter, and producer known for his smooth, soulful sound and work with Top Dawg Entertainment.
-
C.
.si
.si is the country code top-level domain (ccTLD) assigned to websites associated with Slovenia.
-
D.
ISA
ISA (Industry Standard Architecture) is an early computer bus standard used in IBM PCs and compatible systems to connect expansion cards and peripherals to the motherboard.
-
E.
ISA
ISA is the acronym for the International Seabed Authority, the intergovernmental organization responsible for regulating mineral-related activities in the international seabed area beyond national jurisdiction.
- F. None of above. chosen
Statements (48)
| Predicate | Object |
|---|---|
| instanceOf |
SI base unit
ⓘ
coherent SI unit ⓘ unit of time ⓘ |
| baseQuantity | time ⓘ |
| belongsToCategory | base units of the SI ⓘ |
| category | time standard ⓘ |
| constantExactness | exact by definition ⓘ |
| constantExactValue | 9192631770 Hz ⓘ |
| constantName | cesium-133 hyperfine transition frequency ⓘ |
| constantSymbol | Δν(Cs) ⓘ |
| countInDayApprox | 86400 ⓘ |
| definedBy |
cesium-133 hyperfine transition
ⓘ
unperturbed ground-state hyperfine transition of the cesium-133 atom ⓘ |
| definedIn | 13th CGPM resolution 1 (1967) ⓘ |
| definingBody | General Conference on Weights and Measures ⓘ |
| definingBodyAbbreviation |
General Conference on Weights and Measures
ⓘ
surface form:
CGPM
|
| definitionEpoch | 1967 ⓘ |
| definitionText | The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the unperturbed ground state of the cesium-133 atom. ⓘ |
| dependsOnConstant | Δν(Cs) ⓘ |
| dimensionSymbol | T ⓘ |
| dimensionVector | T1 ⓘ |
| governingOrganization | International Bureau of Weights and Measures ⓘ |
| governingOrganizationAbbreviation |
International Bureau of Weights and Measures
ⓘ
surface form:
BIPM
|
| hasMultiple |
day
ⓘ
hour ⓘ microsecond ⓘ millisecond ⓘ minute ⓘ nanosecond ⓘ picosecond ⓘ |
| isBaseOf | SI derived units involving time ⓘ |
| isRealizedBy |
cesium atomic clocks
ⓘ
primary frequency standards ⓘ |
| note | no prefix is used with the second to form minute, hour, or day ⓘ |
| numericalValueOfTransitionFrequency | 9192631770 ⓘ |
| predecessorUnit | ephemeris second ⓘ |
| reaffirmedIn |
26th General Conference on Weights and Measures
ⓘ
surface form:
26th CGPM (2018)
|
| relatedStandard | ISO 80000-3 ⓘ |
| replacedDefinitionOf | mean solar second ⓘ |
| symbol | s ⓘ |
| system | International System of Units ⓘ |
| transitionFrequencyUnit | hertz ⓘ |
| usedFor |
measuring duration
ⓘ
measuring time intervals ⓘ |
| usedIn |
GPS timekeeping
ⓘ
International Atomic Time ⓘ atomic time scales ⓘ Coordinated Universal Time ⓘ
surface form:
coordinated universal time
|
How these facts were elicited
The pipeline generated the facts above by prompting gpt-5.1 with this entity's name + description and the instruction below.
Instruction
You are a knowledge base construction expert. Given a subject entity and a description of it, return factual statements that you know for the subject as a JSON list of dictionaries(triples), where keys must be "subject", "predicate" and "object". The number of facts may be very high, between 25 to 50 or more, for very popular subjects. For less popular subjects, the number of facts can be very low, like 5 or 10. # Requirements - If you don't know the subject at all, return an empty list. - If the subject is not a named entity, return an empty list. - Include at least one triple where predicate is "instanceOf". - Do not get too wordy. - Separate several objects into multiple triples with one object.
Input
Subject: SI second Description of subject: The SI second is the base unit of time in the International System of Units, precisely defined by a fixed number of periods of radiation corresponding to a specific transition in the cesium-133 atom.
Referenced by (5)
Full triples — surface form annotated when it differs from this entity's canonical label.
this entity surface form:
second