In science and mathematics, an open problem or an open question is a known problem that can be accurately stated, and has not yet been solved (no solution for it is known). Some questions remain unanswered for centuries before solutions are found. Two notable examples in mathematics that have been solved and closed by researchers in the late twentieth century are Fermat's Last Theorem and the four color map theorem. An important mathematics open problem solved in early 21st century is the Poincare Conjecture.

Important open problems exist in many fields, such as Physics, Chemistry, Biology, Computer science, and Mathematics. For example, one of the most important open problems in biochemistry is the protein structure prediction problem – how to predict a protein's structure from its sequence.

It is common in graduate schools to point out open problems to students. Graduate students as well as faculty members often engage in research to solve such problems.

Frederick Antony Ravi Kumar Zacharias (born 1946) is an Indian-born, Canadian-American evangelical Christian apologist. Zacharias is the author of numerous Christian books, including Gold Medallion Book Award winner Can Man Live Without God? and bestsellers Light in the Shadow of Jihad and The Grand Weaver. He is the founder and chairman of the board of Ravi Zacharias International Ministries, host of the radio programs Let My People Think and Just Thinking, and visiting professor at Wycliffe Hall of Oxford, where he teaches apologetics and evangelism. Zacharias studied as a visiting scholar at Cambridge University and held the chair in Evangelism and Contemporary Thought at Alliance Theological Seminary from 1981 to 1984. Commentator Chuck Colson referred to Zacharias as "the great apologist of our time."

Zacharias was born in Madras, India. Zacharias claims descent from a woman (of the Nambudiri Brahmin caste) and a low caste Boatman. Missionaries spoke to one of his ancestors about Christianity and thereafter the family was converted. Zacharias grew up in a nominal Anglican household, and he himself was an atheist until the age of 17, when he unsuccessfully tried to commit suicide by swallowing poison. While in the hospital, a local Christian worker brought him a Bible and instructed his mother to read to him out of John 14. Zacharias says that it was John 14:19 that touched him and caused him to commit his life to Christ.

Stephen John "Steve" Nash, OC, OBC (born 7 February 1974) is a South African-born Canadian professional basketball player who plays point guard for the Phoenix Suns of the National Basketball Association (NBA). Nash enjoyed a successful high-school basketball career, and he was eventually given a scholarship by Santa Clara University. In his four seasons with the Broncos, the team made three NCAA Tournament appearances, and Nash was twice named the West Coast Conference Player of the Year.

After graduating from Santa Clara as the team's all-time leader in assists, Nash entered the 1996 NBA Draft and was selected as the 15th pick by the Phoenix Suns. He made a minimal impact, and was traded to the Dallas Mavericks in 1998. By his third season with the Mavericks, he was voted into his first NBA All-Star Game and had earned his first All-NBA selection. Together with Dirk Nowitzki and Michael Finley, Nash led the Mavericks to the Western Conference Finals the following season. However, he became a free agent after the 2003–04 season and returned to the Phoenix Suns.

Max Volume is an American musician, radio personality and voice-over talent. Volume has had remarkable success in his career, as a popular Northern Nevada disc jockey and helped pioneer specialty programming, highlighting then emerging genres like alternative rock and new wave. Volume is a respected studio producer/engineer, with seven albums to his credit, and an accomplished guitarist and solo acoustic artist. Either solo or with The Max Volume Band, he has opened shows for Y&T, UFO, Thin Lizzy, Dave Mason, Pat Travers, Les Dudek, Steve Morse, Mickey Thomas, Foghat, Edgar Winter and Reo Speedwagon, Cosmic Free Way, among others. For three consecutive years (1989,1990 and 1991) Volume was voted "Best Ears In America" by noted industry publication Friday Morning Quarterback (FMQB). In 2001, Volume was inducted into the Nevada Broadcasters Association Hall of Fame. Volume is the Afternoon Drive DJ Mondays through Fridays on Reno, Nevada Classic rock station KOZZ.

Born Glenn Bailey on February 19, 1956, Volume was raised in Glendale, California. He graduated from Crescenta Valley High School in La Crescenta California in 1974. (Volume earned his Associate Degree from Truckee Meadows Community College in 2006.) Volume developed an interest in music at an early age after receiving a guitar from his aunt Christine at age nine. He soon began teaching himself to play. By age 12 Volume was performing and recording. His father, Ralph, the Chief Deputy Coroner of Los Angeles County, did not support his musical aspirations, due to the amount of dead young guitar players in the L.A. County Morgue. His mother Joni was the International President of Sweet Adelines International and often bought him song books with guitar tablature, in which he studied his heroes Jimmy Page, Pete Townshend and Neil Young.