a disaster is a lot like a revolution when it comes to disruption and improvisation, to new roles and an unnerving or exhilarating sense that now anything is possible.

We can imagine almost anything, but only a tiny fraction of what we imagine can become real. There is no easy way to verify how much change is possible. Hard-nosed realists may be right much of the time, but then, periodically, they become dramatically wrong. Wild-eyed visionaries may be wrong much of the time, but occasionally they become dramatic