Ranges & Force Carriers of the Four Fundamental Forces of Nature

Instructor: Matthew Bergstresser

Matthew has a Master of Arts degree in Physics Education. He has taught high school chemistry and physics for 14 years.

There are four fundamental forces in the universe: gravitational, electromagnetic, weak nuclear and strong nuclear. In this lesson, we will focus on the range of these forces and their force carriers.

Range of Force Carriers

Let's do a thought experiment. Pretend you go outside with a friend and move a certain distance apart and call to them. They then call to you what you said. If you can hear each other, you increase the distance between the two of you and repeat the process. Keep doing this until you can no longer hear each other. The distance you are apart at this time is the range of the sound you make. This experiment is an analogy for how far the force carriers operate creating the four fundamental forces of nature. A force carrier is an object on the atomic scale that when expelled from a particle and absorbed by another particle, transmits a force. Each of the fundamental forces of the universe has a specific charge carrier. Let's go through each of them.

Gravity Force Carrier

The weakest fundamental force in the universe is the gravitational force. It is solely an attractive force between masses. According to Newton's law of gravitation, the magnitude of the gravitation force can be calculated by multiplying the masses, the universal gravitational constant 'G' and dividing by the square of the distance between the centers of the masses.

Gravity between a probe and a planet

There is no limit to the range of the gravitation force, and the force carrier is the hypothesized particle called the graviton. This particle hasn't been observed in nature, but it must exist in order for gravity to exist. Since this force acts at infinite distances, it must have no mass itself.

Weak Nuclear Force Carrier

The weak nuclear force is about 1010 stronger than the gravitational force. The weak nuclear force may be stronger than the gravitational force, but it only acts at a distance within the size of a proton, which is around 10-18 meter. The force carrier for the weak nuclear force are weak vector bosons, which have the symbols W+, Z0, and W-. The exchange of these particles causes one type of charged particle to turn into another type of charged particle. For example, when the nucleus of an atom has too many neutrons compared to the quantity of protons, an interaction occurs between weak vector bosons. This causes a neutral neutron to turn into a positively charged proton. To keep with the conservation of mass and electrical charge, a mass-less negatively charge particle called a beta-minus particle is ejected from the atom's nucleus. This process is known as radioactive decay. Let's now move to the next strongest fundamental force, which is the electromagnetic force.

Electromagnetic Force Carrier

The electromagnetic force is almost 1040 times stronger than the gravitational force. An easy way to show the electromagnetic force is stronger is to hold a magnet and put a paperclip on it. Gravity is pulling down on the paperclip, but the electromagnetic force easily counters it.

The interaction of magnets is due to the electromagnetic force

The magnitude of the electromagnetic force that exists between charged particles follows the same equation structure as the gravitation force, but the constant is Coulomb's constant 'k'. This means the range of this force is also infinite, but it only exists between charged particles. Since there are two types of charge, this force can be repulsive between like charges or attractive between opposite charges. Photons are the charge carriers that transmit the electromagnetic force. The last fundamental force we need to discuss is the strongest and is called the strong nuclear force.

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