Notable achievements in science?

“Notable” can mean a discovery that changed how we understand the world, or an invention that changed how we live. A few milestones stand out across different fields:

• Germ theory of disease: Evidence that microorganisms cause many illnesses transformed medicine, sanitation, and surgery.
• Vaccination: From smallpox vaccination to modern vaccines, immunization has prevented millions of deaths and, in smallpox’s case, helped eradicate a human disease.
• The periodic table: Organizing chemical elements by their properties gave scientists a powerful way to understand matter and predict relationships between elements.
• Relativity and quantum mechanics: These theories reshaped physics, explaining phenomena from gravity and the motion of planets to atoms and subatomic particles.
• The structure of DNA: Understanding how genetic information is stored and copied opened the way for modern genetics, biotechnology, and new approaches to medicine.
• Plate tectonics: The theory that Earth’s outer shell is divided into moving plates brought together evidence about earthquakes, volcanoes, and the formation of continents.
• Space exploration: Satellites, crewed missions, and robotic spacecraft have expanded our knowledge of Earth, the Moon, and other worlds while supporting everyday services such as communications and weather forecasting.
• Recent advances: Detecting gravitational waves confirmed a striking prediction of relativity, while mRNA vaccines showed how quickly a new vaccine approach can be developed and deployed.

These achievements were rarely the work of one person or a single moment. They grew from repeated observations, experiments, debate, and improvements by many researchers. Which milestone would you add to the list?