"The function of science is to reassure; the purpose of art is to upset. Therein lies the value of each."
Science, by definition, is anything can be observed, tested, and repeated. When people have questions about the world, then they use science for clarification, not reassurance. "Reassurance" assumes that a person was upset or lacked confidence, but then he or she regained his or her original peace of mind. Science does not reassure. It can frustrate and lead to further questions, but its main purpose is clarification.
Art is a creative expression of somebody's perspective on the world or current issues. It can be based on science, but it is subjective, while science should be objective. Art can certainly upset people, but can also soothe, encourage, and yes, reassure.
It can be agreed that science can upset people. If it does, then it is not real science. Evolution, for example, upsets people who believe that the world was created in six literal days and that man was created by an intelligent designer, not by chance or by millions of years. Evolution, however, is not a real science. It is only a body of theories that cannot be observed, tested, or repeated. These theories, indeed, are actually art forms, creative expressions of somebody's perspective.
In Medieval times, Copernicus and Galileo observed that the earth revolved around the sun, and it did upset the religious people of the day. These conclusions, however, were observable, testable and repeatable. Copernicus and Galileo did use proper science, and it clarified something that was not clear to them. It did not reassure anybody, however, that the world revolved around the earth.
There is more to art than controversy. The song, "Imagine" by John Lennon is upsetting. It has a beautiful tune, but its lyrics praise a world without heaven. This is very upsetting to people who long to see deceased loved ones and divine intervention to stop the wars and injustices of this planet. Art can be upsetting, but that is not its main purpose. A realistic painting of a little ship against a massive tidal wave is not upsetting, but majestic and awe-inspiring. Mary Cassatt uses paint to portray women in peaceful situations; some of these women are newly grown-up, causing bitter-sweetness, and others hold babies in their arms, displaying contentment.
Art and science are both valuable. Art is subjective, while science is objective. Science's very value is its objectivity. Something will be true no matter how many times someone experiments on it. Art's value is not in its controversy or subjectivity, but in its ability to free people to express their emotions.