1986: The Chernobyl nuclear disaster (Ukraine), the most severe in history. In December 2016, the UN proclaimed 26 April as the "International Chernobyl Disaster Remembrance Day". This event marked a turning point in the global monitoring of radioactivity and transboundary atmospheric pollution.

1994: Physicists at the Fermi National Accelerator Laboratory (Fermilab) announce the first evidence of the top quark's existence. This elementary subatomic particle is the most massive of the six known quarks. Its discovery confirmed the structure of the Standard Model of physics—an essential theoretical framework for understanding the birth of the Universe.

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