(CNN)Here's a look at the life of former US Secretary of Defense Ashton B. Carter.
Birth date: September 24, 1954
Birth place: Philadelphia, Pennsylvania
Birth name: Ashton Baldwin Carter
Father: William Stanley Carter, a psychiatrist and neurologist
Mother: Anne (Baldwin) Carter
Marriages: Stephanie (DeLeeuw) Carter; Clayton Spencer (divorced)
Children: with Clayton Spencer: William, Ava
Education: Attended Edinburgh University, 1975; Yale University, B.A. in physics and medieval history, 1976 (summa cum laude); Oxford University, Rhodes Scholar, Ph.D. in theoretical physics, 1979
Carter has been awarded the Department of Defense Distinguished Service Medal on several occasions.
"He's also a physicist, which means that he's one of the few people who actually understands how many of our defense systems work," said US President Barack Obama during his nomination announcement.
Regarding his academic interests in both physics and medieval history, Carter once said, "There was no relationship between them in my mind except that both fascinated me." He continued, "It has become a joke among all my friends that, intellectually, I have somehow managed to mix physics and medieval history. It might be an unorthodox combination, but it is an absorbing one."
Carter has served as a member of the Secretary of State's International Security Advisory Board, the Defense Policy Board, the Defense Science Board, and the National Academy of Sciences Committee on Science and Technology for Countering Terrorism.
1980-1981 - Analyst in the Office of Technology Assessment, International Security and Commerce Program, US Congress.
1981-1982 - Analyst in program analysis and evaluation, Office of the Secretary of Defense.
1982-1984 - Serves as a research fellow within the Center for International Studies at the Massachusetts Institute of Technology.
1984-1986 - Assistant professor at the Center for Science and International Affairs (now the Belfer Center for Science and International Affairs), John F. Kennedy School of Government, Harvard University.
1986-1988 - Associate professor, Harvard University.
1988-1990 - Professor and associate director of the center at Harvard University.
1990-1993 - Serves as director of the Center for Science and International Affairs (now the Belfer Center for Science and International Affairs), John F. Kennedy School of Government, Harvard University.
1993-1996 - Serves as assistant secretary of defense for international security policy, US Department of Defense.
1998 - Recipient of the Defense Intelligence Medal.
April 2009-October 2011 - Under Secretary of Defense for Acquisition, Technology and Logistics
August 2, 2011 - President Obama nominates Carter to replace Deputy Secretary of Defense William J. Lynn III.
September 23, 2011 - The US Senate unanimously confirms Carter as the deputy secretary of defense.
October 6, 2011-December 3, 2013 - Deputy Secretary of Defense.
December 5, 2014 - President Obama nominates Carter to succeed Secretary of Defense Chuck Hagel. Hagel's resignation was announced November 24, 2014.
February 12, 2015 - Is confirmed by the Senate, 93 to 5, to be the new secretary of defense.
February 17, 2015-January 19, 2017 - Serves as the 25th secretary of defense.
July 12, 2016 - Makes an unannounced visit to Afghanistan to meet with the country's leaders and visit with US forces who are battling a resilient Taliban. Carter's trip comes a week after President Obama's announcement 8,400 troops will remain in Afghanistan through the end of 2017, a higher number than the 5,500 troops originally planned.