Any probe which crosses the horizon of a black hole should be absorbed. In
M(atrix) theory, for 0-brane probes of Schwarzschild black holes, we argue
that the relevant absorption mechanism is a tachyon instability which sets
in at the horizon. We give qualitative arguments, and some quantitative lar
ge-N calculations, in support of this claim. The tachyon instability provid
es an attractive mechanism for infalling matter to be captured and thermali
zed by a Schwarzschild black hole.