The Johns Hopkins University Applied Physics Laboratory (Applied Physics Laboratory, or APL) is a not-for-profit university-affiliated research center (UARC) in Howard County, Maryland. It is affiliated with Johns Hopkins University and employs 8,000 people as of 2022. The lab serves as a technical resource for the Department of Defense, NASA, and other government agencies. APL has developed numerous systems and technologies in the areas of air and missile defense, surface and undersea naval warfare, computer security, and space science and spacecraft construction. While APL provides research and engineering services to the government, it is not a traditional defense contractor, as it is a UARC and a division of Johns Hopkins University. APL is a scientific and engineering research and development division, rather than an academic division, of Johns Hopkins.
Hopkins' Whiting School of Engineering offers part-time graduate programs for Lab staff members through its Engineering for Professionals program. Courses are taught at seven locations in the Baltimore-Washington Metropolitan Area, including the APL Education Center.
APL was created in 1942 during World War II under the Office of Scientific Research and Development's Section T as part of the Government's effort to mobilize the nation's science and engineering expertise within its universities. Its founding director was Merle Anthony Tuve, who led Section T throughout the war. Section T was created on August 17, 1940. According to the official history of the Office of Scientific Research and Development, Scientists Against Time, APL was the name of Section T's main laboratory from 1942 onward, not the name of the organization overall. Section T's Applied Physics Laboratory succeeded in developing the variable-time proximity fuze that played a significant role in the Allied victory. In response to the fuze's success, the APL created the MK 57 gun director in 1944. Pleased with the APL's work, the Navy then tasked it with the mission to find a way to negate guided missile threats.