  The Brownian web is a random variable consisting of a Brownian motion
starting from each space-time point on the plane. These are independent until
they hit each other, at which point they coalesce. Tsirelson mentions this
model in his paper "Scaling limit, Noise, Stability", along with planar
percolation, in suggesting the existence of a two-dimensional black noise. A
two-dimensional noise is, roughly speaking, a random object on the plane whose
distribution is translation invariant and whose behavior on disjoint subsets is
independent. Black means sensitive to the resampling of sets of arbitrarily
small total area.
  Tsirelson implicitly asks: "Is the Brownian web a two-dimensional black
noise?". We give a positive answer to this question, providing the second known
example of such after the scaling limit of critical planar percolation.
