The mark, to me, of a constructive argument is one that looks at a specific problem and says, 'What shall we do about this?' And a nonconstructive one is one that tries to label people.Gloria Steinem
One of the major problems with long-term deep space human flight is the requirement for radiation shielding.Buzz Aldrin
The most creative people are motivated by the grandest of problems that are presented before them.Neil deGrasse Tyson