Four forces in nature
There are 4 fundamental forces that have been identified.
In our present Universe they have rather different properties.
Properties of the Fundamental Forces
- The strong interaction is very strong, but very short-ranged.
It acts only over ranges of order 10-13 centimeters.
It is responsible for holding the nuclei of atoms together.
It is basically attractive, but can be effectively repulsive in some circumstances.
- The electromagnetic force causes electric and magnetic effects such as the repulsion between like electrical charges or the interaction of bar magnets.
It is long-ranged, but much weaker than the strong force.
It can be attractive or repulsive, and acts only between pieces of matter carrying electrical charge.
- The weak force is responsible for radioactive decay and neutrino interactions.
It has a very short range and, as its name indicates, it is very weak.
- The gravitational force is weak, but very long ranged.
It is always attractive, and acts between any two pieces of matter in the Universe since mass is its source.