thumb|right|upright|Groves at his desk, 1945 Meanwhile, Groves had met with J. Robert Oppenheimer, a physicist at the University of California, Berkeley, and discussed the creation of a laboratory where the bomb could be designed and tested. Groves was impressed with the breadth of Oppenheimer's knowledge. He had a long conversation on a train after a meeting in Chicago on October 15, when Groves invited Oppenheimer to join Marshall and Nichols on the 20th Century Limited train returning to New York. After dinner on the train they discussed the project while squeezed into Nichols's one-person roomette, and when Oppenheimer left the train at Buffalo, Nichols had no doubt that he should direct the new lab. Groves saw that Oppenheimer thoroughly understood the issues involved in setting up a laboratory in a remote area. These were features that Groves found lacking in other scientists, and he knew that broad knowledge would be vital in an interdisciplinary project that would involve not just physics, but chemistry, metallurgy, ordnance, and engineering.
thumb|right|upright|Groves at his desk, 1945 Meanwhile, Groves had met with J. Robert Oppenheimer, a physicist at the University of California, Berkeley, and discussed the creation of a laboratory where the bomb could be designed and tested. Groves was impressed with the breadth of Oppenheimer's knowledge. He had a long conversation on a train after a meeting in Chicago on October 15, when Groves invited Oppenheimer to join Marshall and Nichols on the 20th Century Limited train returning to New York. After dinner on the train they discussed the project while squeezed into Nichols's one-person roomette, and when Oppenheimer left the train at Buffalo, Nichols had no doubt that he should direct the new lab. Groves saw that Oppenheimer thoroughly understood the issues involved in setting up a laboratory in a remote area. These were features that Groves found lacking in other scientists, and he knew that broad knowledge would be vital in an interdisciplinary project that would involve not just physics, but chemistry, metallurgy, ordnance, and engineering.