What is the densest thing on Earth?

Asked by: Georgia

Answer

Leaving aside the obvious political humor potential in your question, you did ask about the densest THING, not the densest material, on Earth. That would probably be a neutron. While many subatomic particles are considered points, and thus could be thought of as having an infinite density, the neutron has a measurable size (about 10^-15 m in diameter) as well as mass (about 1.7 x 10^-27 kg). Those numbers result in a density of about 10¹⁸ kg/m³.

That value matches the estimated density of neutron stars, the densest objects known in the Universe. (A black hole's mass is concentrated in an immeasurable singularity). A single neutron is a smaller (MUCH smaller!) version of a neutron star, and the Earth is loaded with neutrons.
Answered by: Paul Walorski, B.A. Physics, Part-time Physics Instructor