The smallest and heaviest thing in the world is a neutron star. Neutron stars are incredibly dense celestial objects that are formed when a massive star collapses under its own gravity. The resulting explosion creates an extremely dense and compact object, which is usually no larger than 10 kilometers in diameter.
Neutron stars are composed almost entirely of neutrons, hence their name. These neutrons are so densely packed that a single sugar-cube-sized sample of neutron star material would weigh more than a mountain on Earth. As such, neutron stars are the densest known objects in the universe, with a density that is estimated to be around one to two orders of magnitude greater than that of an atomic nucleus.
Neutron stars can also be incredibly massive, with a mass of 1.4 to 2.1 times that of our sun. This means that, for something so small, it has an extremely high mass-to-volume ratio and is the heaviest object in the universe.
Neutron stars also have incredibly strong magnetic fields, which can be up to 1,000 times stronger than Earth’s magnetic field. This magnetic field creates a powerful gravity force that pulls in material from the surrounding space, making the star even denser, and making it the smallest and heaviest thing in the universe.
Neutron stars can also rotate very quickly, spinning at rates of up to several hundred times per second. This rotation combined with their incredibly strong magnetic fields, creates a powerful source of energy, which can be detected as radio waves and can be seen as pulsars in the night sky.
The incredible density, mass and rotation of neutron stars make them the smallest and heaviest thing in the universe. These incredibly dense objects are fascinating to study and can give us insight into the nature of the universe.