From the chemistry behind dazzling colors to the psychology of awe and the history of patriotic celebration, CAS faculty explain why fireworks have become one of America’s most enduring Fourth of July traditions.

What makes fireworks such a compelling sensory experience for the brain?

“Each burst is unpredictable, so the brain can’t adapt the way it does to a familiar view. The extreme contrast—sudden brightness against a dark sky, sharp bangs against silence—is exactly what our sensory systems are tuned to detect. So the mix of unpredictability, intense contrast, and multisensory stimulation, paired with emotional weight of the celebratory moment, makes vivid imprints in our memory banks.”—Sam Ling, associate professor, Psychological & Brain Sciences

Why are fireworks so central to the American experience?

“In a nation shaped by ongoing debate over what it means to be American, public rituals like fireworks have offered a way for people to express attachment to the country’s founding ideals—even as those ideals, and who belongs within them, remain contested.” —Bruce J. Schulman, William E. Huntington Professor of History

What happens chemically when fireworks light up and explode?

“Fireworks get their colors from the different metal salts. When heated to very high temperatures by burning gunpowder, electrons in the metals are quickly excited and then relax, and energy is emitted in the form of light. Each element has a different electron configuration, so it emits different wavelengths of light. To work, the metals must be precisely packed, there must be enough gunpowder to get them into the air, and they must explode at precisely the right time with enough heat to cause the metal to glow.” —Eric Cueny, assistant professor, chemistry

Why have fireworks become such an enduring part of public celebration?

“As a part of periodic rites of celebrationas—on July 1st in Canada, July 4th in the U.S., or July 14th in France—or as a part of individual events—as in weddings—fireworks impart a feeling of importance for the occasions and a sense of shared participation and belonging to observers. They can also represent, like gift-giving in some societies, an act of generosity that enhances or confirms the status or prestige of the providers.” —Parker Shipton, professor of anthropology and African studies