1) The coldest known temperature in the universe was achieved in a laboratory in 2019, reaching a fraction of a degree above absolute zero (-273.15 degrees Celsius).

2) The ozone layer, located in the Earth's stratosphere, protects us from harmful ultraviolet (UV) radiation.

3) Serena Williams, an American tennis player, has won a total of 23 Grand Slam singles titles, making her one of the most successful players in the history of the sport.

4) The Eiffel Tower can be 15 cm taller during the summer due to thermal expansion.