Albert Einstein’s theory of gravitational redshift was proven after a telescope in Chile observed a black hole.
Source
The Summer Olympic Games opening ceremony was held outdoors for the first time ever.
The US Postal Service was founded.
The opera 'Parsifal' by Richard Wagner premiered in Bayreuth, Germany.
Niger President Mohamed Bazoum was removed from office by a military coup.
President Harry Truman signed the National Security Act.
