Kagan and Soai Win Chemistry Nobel for Solving Molecular Mirror Mystery

The Royal Swedish Academy of Sciences awarded the 2026 Nobel Prize in Chemistry to France's Henri Kagan and Japan's Kenso Soai on Wednesday. The 1 million USD prize recognizes their work explaining why living organisms use only one mirror-image form of molecules like amino acids and sugars, a phenomenon known as homochirality.

Kagan, 95, took the first crucial step in 1986 by discovering a way to amplify a tiny imbalance between mirror-image molecules during chemical reactions. Soai, 76, later demonstrated that this amplification could occur spontaneously through autocatalysis, where the product of a reaction catalyzes its own formation.

“This is the most exciting day in my life, I am very glad to share this prize with Professor Henri Kagan.”

Their combined discoveries solved a puzzle dating back to Louis Pasteur's 19th-century observation that tartaric acid exists in two mirror forms. The breakthrough allows chemists to design reactions that produce only the desired molecular "hand," which is critical for pharmaceuticals where the wrong version can be ineffective or toxic.

The thalidomide tragedy of the 1950s and 60s illustrated the stakes: one mirror form of the drug treated morning sickness while the other caused severe birth defects. Kagan and Soai's work provides the tools to prevent such disasters.

French President Emmanuel Macron and Japanese Prime Minister Sanae Takaichi congratulated the laureates. Soai said it was the most exciting day of his life, while Kagan's daughter praised the creativity of his lifelong research.