Minkowski space is shown to be globally stable as a solution to the massive Einstein-Vlasov system. The proof is based on a harmonic gauge in which the equations reduce to a system of quasilinear wave equations for the metric, satisfying the weak null condition, coupled to a transport equation for the Vlasov particle distribution function. Central to the proof is a collection of vector fields used to control the particle distribution function, a function of both spacetime and momentum variables. The vector fields are derived using a general procedure, are adapted to the geometry of the solution and reduce to the generators of the symmetries of Minkowski space when restricted to acting on spacetime functions. Moreover, when specialising to the case of vacuum, the proof provides a simplification of previous stability works.
ContentsDate: November 7, 2017. 1 6. The Einstein equations 51 6.1. Weak L ∞ decay estimates 52 6.2. The sharp decay estimates for the first order derivatives 55 6.3. The commutators and Lie derivatives 59 6.4. The sharp L ∞ decay estimates for higher order low derivatives 62 6.5. The energy estimate 63 6.6. Higher order L 2 Energy estimates 64 7. The continuity argument and the proof of Theorem 1.2 68 References 701 Note that the Einstein equations (1.1) are equivalent to Ric(g) αβ = T αβ − 1 2 g αβ trg T .
4where Γ α βγ are the Christoffel symbols of the metric g with respect to a given coordinate chart (t, x 1 , x 2 , x 3 ). Define X(s, t, x, p ) 0 = s and P (s, t, x, p ) 0 = 1. The notation X(s), P (s) will sometimes be used for X(s, t, x, p ), P (s, t, x, p ) when it is clear from the context which point (t, x, p ) is meant, and the notation X (s) = (s, X(s)) will sometimes be used.It follows that the Vlasov equation (1.3) can be rewritten as,for all s. The notation (y, q) will be used to denote points in the mass shell over the initial hypersurface, P| t=0 . In Theorem 1.2 it is assumed that f 0 has compact support; |y| ≤ K and |q| ≤ K ′ for (y, q) ∈ supp(f 0 ), for some constants K, K ′ . Under a relatively mild smallness assumptions on h = g − m, see Proposition 2.1, it follows that there exists c < 1, depending only on K ′ , such that solutions of the Vlasov equation satisfyfor |I| ≤ N . Here the constants D k depend only on C ′ N , K, K ′ and c, and ε 0 depends only on c.Remark 1.4. The proof of Theorem 1.3 still applies when a ≥ 1, though the theorem is only used in the proof of Theorem 1.2 for some fixed 1 2 < a <1. The case of a = 1 is omitted in order to avoid logarithmic factors. The proof of an appropriate result when a > 1 is much simpler, although, when Theorem 1.3 is used in the proof of Theorem 1.2, one could not hope for the assumptions (1.17) to hold with a > 1, see Section 1.5.2.Remark 1.5. In Section 5 a better L 2 estimate in terms of t behaviour, compared with the L 2 estimate of Theorem 1.3, is shown to hold for Z I T µν , which involves one extra derivative of Γ. See Proposition 5.8. It is important however to use the L 2 estimate which does not lose a derivative in t...