Thousands of demonstrators took to the streets of Yokohama the weekend of Jan. 14-15 to show their support for a nuclear power-free world. Organizers of the Global Conference for a Nuclear Power Free World claimed 6,000 participants from some 30 countries on the first day and 5,500 on the second. Newspaper reports put the number closer to 2,000.

Whatever the actual numbers, including a no-doubt large Internet audience for the live broadcast, the conference showed that organized opposition to nuclear power has gained momentum in the wake of the Fukushima nuclear plant crisis.

The conference shows all the signs of turning into a coherent, focused movement. For a movement to have impact, though, it needs more than people in parks — it also needs viable ideas. This conference had both. Rather than calling the weekend a "protest" or "rally," they called it a "conference." And rather than demanding an immediate ban, they called for transitions toward a nuclear-free world. That softer, more sensible approach is more likely to succeed.