1) The Earth's core is hotter than the surface of the Sun.

2) The concept of campaign finance refers to the funding and financial resources required to support political campaigns, including donations from individuals, organizations, and political action committees (PACs).

3) The world's oldest living plant is believed to be a clonal shrub called "Old Tjikko" in Sweden, estimated to be over 9,500 years old.

4) The concept of 3D printing, also known as additive manufacturing, was first introduced in the 1980s and has since revolutionized prototyping and small-scale production.