Invariant spacetime interval
Lorentz transformations preserve a combined space-time separation.
Key knowledge
Between two events in flat spacetime, Δs² = Δx² + Δy² + Δz² − c²Δt² is invariant under Lorentz transformations between inertial frames, using the spatial-positive sign convention.
Values and equations
Δs² = Δx² + Δy² + Δz² − c²Δt²
- Δs²
- Squared spacetime interval in the stated sign convention m²
- Δx, Δy, Δz
- Spatial coordinate differences between the same two events m
- Δt
- Time coordinate difference between those events s
- c
- Speed of light in vacuum m s⁻¹
Conditions and scope
- Coordinates are inertial Cartesian coordinates in special relativity.
- The opposite overall sign is also a common convention; remain consistent.
- Curved-spacetime geometry is outside this formula's global scope.
Sources · 2
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
OpenStax 5.5, spacetime interval and Lorentz invariance.
2026-10-10 · Flat-spacetime interval with explicit sign convention and units only; no general-relativistic metric is supplied.
Foundational review
2026-10-10 · Fresh primary-source inspection of the complete compact record, including every statement, equation, quantity and material condition, followed by independent AI editorial review. This check does not certify all linked lessons or every passage of every cited publication.
Sources from other places
Agreement within this scope
The flat-space interval with spatial-positive metric is invariant under Lorentz transformations.
Multiplying the metric by an overall minus sign is an alternative convention.
University of Oxford · Department of Physics
- Relativity · invariant quantities United KingdomEnglish
3.4.2 equations3.36–3.41, pp38–40
- Relativity · invariant quantities
Entry details
Permanent link to this entry ↗- Record identity
- physics-spacetime-interval
- Revision
- core.1
- Structured reference record
- Essential core · first collection · University core expansion