Planck mission will help achieve Planck's mission.

When Max Planck enrolled at the University of Munich in 1874, he planned to study mathematics. But then physics caught his attention and he changed his major, despite a professor's warning that everything worth knowing about physics had already been discovered.

But Planck persevered with physics. He wanted to understand the nature of the universe more deeply. And that is precisely the goal of the spacecraft soon to be launched bearing Planck's name.

Planck (the man) became an authority on thermodynamics. In 1900, while pondering disparities between theories of how hot bodies should glow and actual experiments, he arrived at a formula that revolutionized science, relating radiation's frequency to its energy by a mathematical constant that, like the new spacecraft, bears Planck's name.

Planck (the man, not the constant) quickly realized that his formula muddled the view of radiation (light and all its electromagnetic relatives) as smooth and continuously divisible. Instead, it was absorbed and emitted in chunks called quanta. Planck resisted the implication that light also traveled through space as quanta, but Einstein forced the world to accept the whole meaning of what Planck had perceived.

Back then, a century ago, nobody realized that Planck's quanta were the key to understanding the universe itself. But now cosmologists "know" (physics jargon for "strongly suspect") that quanta from the beginning of time generated seeds of matter that grew into the galaxies that populate the cosmos today. Explaining the origin of the galaxies, the stars, star products (such as people) and even, perhaps, the universe all depends on mapping the quantum signatures written in the radiation that the Planck spacecraft will scrutinize.

Ron Cowen's description of the Planck mission (Page 16) provides details of the science-the efforts to detect polarized radiation and infer the activity of gravitational waves, attempts to understand the immediate aftermath of the Big Bang and theories explaining it, the quest to identify the strange repulsive energy that accelerates the universe's expansion. These endeavors represent the pinnacle of human pursuit of answers to the deepest questions about existence, the sorts of things that drew Planck to physics. It was to the world's benefit that he didn't listen to the guy who said all the physics questions had been answered.

Tom Siegfried, Editor in Chief