1) The universe is estimated to be around 13.8 billion years old.

2) The concept of proportional representation, used in some electoral systems, aims to ensure that political parties' representation in government aligns more closely with the proportion of votes they receive from the electorate.

3) Sushi is a traditional Japanese dish made of vinegared rice combined with various ingredients, such as raw or cooked seafood, vegetables, and nori (seaweed). It is known for its artful presentation and delicate flavors, and has gained immense popularity worldwide. Sushi can take many forms, including nigiri (hand-pressed rice topped with ingredients) and maki (rolled sushi wrapped in seaweed), and is often enjoyed with soy sauce, wasabi, and pickled ginger.

4) Michael Phelps, an American swimmer, has won a total of 28 Olympic medals, including 23 gold medals, making him the most decorated Olympian of all time.