Three quarks for muster mark! Sure he hasn't got much of a bark And sure any he has it's all beside the mark. —James Joyce, Finnegans Wake

As he later explained in his 1995 book The Quark and the Jaguar, physicist Murray Gell-Mann had the sound of his theorized particle in mind before discovering the spelling he would eventually adopt from a book James Joyce published in 1939. “The number three fitted perfectly the way quarks occur in nature,” Gell-Mann wrote, referring to how three quarks make up a proton, itself a component, along with the electron and neutron, of atoms. Although George Zweig, who also theorized this fundamental particle in 1964, preferred the term “ace,” quark eventually stuck.

Not so, perhaps, the quark's shared preeminence with the lepton as the most fundamental component of matter. Tantalizing hints in various experiments point to still smaller constituents, dubbed preons, in the particle zoo known to physics. You will learn from “The Inner Life of Quarks,” by Don Lincoln, beginning on page 36, that each quark could, in turn, be made of three preons—or perhaps five, depending on which theory you prefer. By 2014 or 2015, after successive upgrades to CERN's Large Hadron Collider near Geneva, scientists hope to find out.

Mysteries drive a lot of science, but we prefer our policy leaders' intentions to be clear. That—and an evidence-based belief that the support of research and innovation has powered humanity's current levels of prosperity—is why Scientific American is serving as media partner for an important public discussion.

We worked with and a host of the nation's preeminent scientific organizations, such as the American Association for the Advancement of Science, to secure answers to 14 top scientific questions from presidential candidates Mitt Romney and Barack Obama. You can read their full answers at (We also sent a subset of the questions to legislators who have key roles in science policy.)

See our Science Agenda “Future Jobs Depend on a Science-Based Economy,” on page 12, for a further discussion of the economic importance of science and turn to “America's Science Problem,” by science writer Shawn Lawrence Otto, starting on page 62, to learn about a troubling issue that could impede our nation's progress and to see a report on how well the candidates answered the questions. We hope you find the results as useful as they are thought-provoking.