Was born in 1933 in Vilna .He was recognized from an early age as possessing extraordinary artistic talent. In 1941, Bak and his family were forced to move into the Vilna Ghetto. At the age of nine, he held his first exhibition inside the ghetto .In September 1943, with the destroying of the ghetto, they were deported to a forced labor camp, where the father was.
By the end of the war, Samuel and his mother were the only members of his extensive family to have survived.
Bak and his mother moved to Lodz, Poland and from 1945 they lived in Displaced Persons camps in Landnsberg, Germany and in 1948, they immigrated to Israel. In 1952, he studied art at the Bezalel Academy of Arts and Design .In the years 1953-1956 he served in the IDF.
In the beginning of the 1950's, he was the illustrator of the main article in the weekly paper "Ha'olam Haze" (this world) and was also a scenarios designer in the theater. Bak graduated the high school for beautiful arts (beaux arts) in Paris. In the years 1959-1966 he was living in Italy, where he developed his artistic style, "Figurative Surrealism".
In the years 1966-1974 he lived in Israel, in 1974-1977 in New York, and in 1977-1980 he returned to Israel. In 1980-1984 he was living in France, and in 1984-1993 in Switzerland. Then he immigrated to the U.S.A.
In the center of Bak's painting stands the conception of the past, of a painting related to the Jewish history.
"The organization of the theme and the lighting creates dramatic theatricality and not once also monumental, emphasizing the feeling of absurdity. Spectacular painting of accurate realism, inspired by the Renaissance art and by the genre of historical painting." (The curator, Carmela Rubin).
In December 2006, "Yad Vashem" opened a retrospective exhibition - "a journey and a load", presenting 115 of his art works, and with it an album by that name, with the editing of Yehudit Shen-Dar, the exhibition curator.
His art works can be found in many museums and collections in Israel and around the world.