Creative ideas are not always solo strokes of genius, argues Ed Catmull, the computer-scientist president of Pixar and Disney Animation Studios, in the current issue of the Harvard Business Review. Frequently, he says, the best ideas emerge when talented people from different disciplines work together.

This week, Nature begins a series of six Essays that illustrate Catmull's case. Each recalls a conference in which a creative outcome emerged from scientists pooling ideas, expertise and time with others — especially policy-makers, non-governmental organizations and the media. Each is written by someone who was there, usually an organizer or the meeting chair. Because the conferences were chosen for their societal consequences, we've called our series 'Meetings that Changed the World'.

This week, François de Rose relives the drama of the December 1951 conference at the UNESCO headquarters in Paris that led to the creation of CERN, the European particle-physics laboratory based near Geneva (see page 174). De Rose, then France's representative to the United Nations Atomic Energy Commission, chaired the meeting. He had got caught up in the process after becoming friends with Robert Oppenheimer, one of CERN's earliest proponents. De Rose said in a separate interview with Nature that CERN was the result of the capacity of scientists such as Oppenheimer to propose grand ideas, and worry about obstacles later.

Although this approach does not always work, the next few weeks will show that it really has changed the world. In the ensuing half-century, CERN has revolutionized our understanding of the subatomic world; with the switching-on this week of the Large Hadron Collider (see page 156) it promises to scale new heights.

When we began to think about commissioning this series, several difficulties arose. First, we were looking for more than the traditional scientific conference, and it was notable how few of the twentieth century's world-changing meetings had involved scientists taking a lead. As a list emerged, we were faced with another problem: time had sadly depleted the pool of writers. This week's author, for example, is among the few surviving members of a group that met 57 years ago.

The six events that made the final cut took place on three continents and span five decades, from 1951 to the dawn of the new millennium. They represent the twentieth century's promise, and two of its greatest threats. And they illustrate a period in history when scientists felt they should raise a collective voice to advance the public good. The six meetings have something else in common. In wanting to change their world, the scientists involved needed and obtained the support of governments and, in some cases, the media.

In two of the conferences — those related to CERN and the Human Genome Project — scientists organized themselves and others to create new and exciting research endeavours. But the other meetings considered in our series had very different aims. At a 1975 conference held in Asilomar, California, for example, geneticists felt compelled to sound an alarm over DNA modification, then a new technology of uncertain impact. At a meeting in Bellagio, Italy, in 1969, plant scientists were among those who convinced governments and philanthropic foundations to invest in technologies to take the green revolution to the developing world.

As in any series of this nature, some caveats are in order. First, global initiatives are a process in which many decisions are made over many years. In the case of CERN, the Paris 1951 event was not the first official meeting in the institution's history. It was, however, an occasion where private disagreements between governments became public, and where a consensus was eventually found to move the project forward. Without such a consensus, it is debatable whether CERN would have taken the direction it did.

Second, our list is not the final word. There are other candidates for the title of Meetings that Changed the World. And our illustrious attendees' opinions are, of course, personal and often provocative. Readers are invited to have their say at http://network.nature.com/forums/naturenewsandopinion/2359.