Geodesic motion
Free test motion follows the metric connection.
Key knowledge
In general relativity, an ideal force-free test particle follows a metric geodesic: d²x^μ/dλ² + Γ^μ_αβ(dx^α/dλ)(dx^β/dλ) = 0 for an affine parameter λ.
Values and equations
d²x^μ/dλ² + Γ^μ_αβ(dx^α/dλ)(dx^β/dλ) = 0
- x^μ
- Spacetime coordinates, all length units in this convention m
- λ
- Affine parameter chosen with length units m
- Γ^μ_αβ
- Levi-Civita connection coefficients in length coordinates m⁻¹
- μ, α, β
- Spacetime indices; repeated indices summed
Conditions and scope
- Use the torsion-free Levi-Civita connection and smooth coordinates; λ is affine, not arbitrary.
- Neglect self-force, extended-body and spin effects; geometric-optics light rays use null geodesics.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Equations 3.47 and 3.58–3.59: affine geodesics versus general parameterization.
2026-10-10 · Ideal metric geodesic equation only; physical test-particle scope is explicit.
Entry details
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- University reference