Ray was born on July 16, 1931, in Marijampole, Lithuania to Vincas and Genovaite Viskanta. In 1944 his family fled Lithuania, traveling west to Germany. Shortly after WWII, his family was moved to displaced person camps in West Germany. In 1949 the family immigrated to the United States, settling within a large Lithuanian-American community in Chicago.

He received his formal education in Mechanical Engineering, earning a Bachelor of Science degree from the University of Illinois (1955). He went on to complete a master’s (1956) and Ph.D. (1960) degrees from Purdue University.

Starting his career at Argonne National Laboratory, Ray joined Purdue's faculty as an Associate Professor of Mechanical Engineering in 1962. He became the W.F.M. Goss Distinguished Professor of Engineering in 1986. Ray taught at the undergraduate and graduate levels and conducted research in thermal sciences, heat, mass, and radiative transfer until his retirement in 2001.

Ray received recognition over his career not only because of the exceptional quality and productivity of his work, but because of its expansive breadth.  Most of his research was conducted jointly with students.  He guided the work of 64 doctoral, 48 master students and 39 postgraduate researchers. He developed over 540 publications in more than 50 journals in the U.S., Europe, and Japan and presented over 200 keynote papers and invited lectures at national and international conferences, universities, and research institutions.

Among many awards and international recognition, Ray received the U.S. Senior Scientist Award from the Alexander von Humboldt Foundations, was elected member of the U.S. National Academy of Engineering in 1987, and in 1990 as a foreign member of the Lithuanian Academy of Sciences.  He was awarded an Honorary Doctor of Engineering Degree from the Technical University of Munich in 1994 and an Honorary Doctor of Engineering Degree from Purdue University in 2007.

Ray enjoyed socializing with friends and his extended “family” of students. His house and dinner table were frequent venues for many who shared in his immigrant or academic experiences. He enjoyed travel with his wife and friends, a cold beer after mowing the lawn, following international news, and contributing to Lithuanian related cultural and academic causes.

"Ray was a giant in heat transfer," said Eckhard Groll, William E. and Florence E. Perry Head of Mechanical Engineering, and Reilly Professor of Mechanical Engineering. "His legacy lives on today -- not just in the heat transfer area, but in all the hundreds of students and faculty that had the pleasure of working with him."