Conversation so far:
what is meant by force at a distance
Forces can be divided into those that act by direct contact, and those that that act at a distance, where there is no apparent physical contact between the objects.
what is an example of force at a distance
Magnetism, and electrical charge, and gravitation are examples of forces that act at a distance.
what is another type of force besides magnetism, electrical charge, and gravitation
Nuclear force is a force that acts between the protons and neutrons of atoms.
how was nuclear force discovered
The discovery of nuclear force happened when the discovery of the neutron in 1932 revealed that atomic nuclei were made of protons and neutrons, held together by an attractive force.

Question: who discovered the particle
Self-contained rewrite: who discovered the neutron