Ali Akbar Salehi and Ernest Moniz

Diplomats received much of the credit for this year’s historic nuclear deal between Iran and world powers. Yet it was two physicists who negotiated the science required to advance the big-picture politics. Ali Akbar Salehi of the Atomic Energy Organization of Iran and U.S. Energy Secretary Ernest Moniz joined the talks in 2014, employing their expertise to resolve a debate over what limits to place on the Islamic Republic’s centrifuge program. This year, they ironed out an innovative and breakthrough agreement — limiting not only Iran’s production of uranium but also plutonium, which provides a much quicker path to a bomb — and contributed to the deal’s provisions for more robust scientific cooperation in fields from nuclear fusion to cancer therapy.

“Occasionally, a scientist drops into the government at just the right time, with just the right expertise,” former CIA Director John Deutch told the New York Times, speaking of Moniz. The same, it seems, can be said of Salehi.