What Is Diffusion? Explain the Various Form of Diffusion.

Diffusion is one of several transport phenomena that occur in nature. A distinguishing feature of diffusion is that it results in mixing or mass transport, without requiring bulk motion. Thus, diffusion should not be confused with convection, or advections, which are other transport mechanisms that utilize bulk motion to move particles from one place to another. In Latin, "diffundere" means "to spread out".
There are two ways to introduce the notion of diffusion: either a phenomenological approach starting with Fick's laws of diffusion and their mathematical consequences, or a physical and atomistic one, by considering the random walk of the diffusing particles.
Diffusion is the process by which a characteristic spreads across space from one place to another over time. It is the process of dissemination. Diffusion causes ideas and different cultural customs to be spread from one place to another. This makes the world more culturally diverse. There are many types of diffusion: contagious, hierarchical, stimulus, and relocation. These types of diffusions are seen in trends, ideas, transportation, and communication systems. For example, it allows the world to watch events on television and transportation to travel and spread ideas from place to place.

Forms of Expansion Diffusion

Expansion diffusion is idea or innovation spreads outward from the hearth.

Contagious Diffusion
Contagious diffusion is the rapid, widespread diffusion of a characteristic throughout the population. Ideas that are spread through contagious diffusion are spread throughout the population like the flue would. It starts with one person or place and it keeps spreading until it is worldwide. Ideas that spread through contagious diffusion start in a populated area, then other cities adopt the idea and it keeps spreading from there. Unlike hierarchical diffusion, everyone picks up on the trend and idea around the same time causing it to become contagious, like a wave on the crowd. It starts from a “center” or hearth and diffuses out from there to the rest of the population. Contagious diffusion goes along with many ideas that relate to popular culture each year.

Hierarchical Diffusion
Hierarchical diffusion is the spread of an idea from persons or nodes of authority or power to other persons or place. This type of diffusion usually results in import authority figures in a community such as a political leader or socially elite people. Also, the trend or idea starts in a major city, then the other cities follow a while after. This type of diffusion usually starts in a populated early and slowly diffuses to less and less populated areas. An example of this would be architecture. This is because it may start in a certain area of the world, then someone from that country moves and builds that same style in another area which spreads through the rest of that area and so on and so forth. Another example is hip hop and rap. It started from low-income African Americans in urban areas and diffused from there. Another example is “command centers” in New York, Tokyo, and London employ modern telecommunications to send out their orders to factories, shops, and research centers.

Stimulus Diffusion
Stimulus diffusion is the spread of an underlying principle, even though a characteristic itself apparently fails to diffuse. Also, an idea or innovation sparked by an idea that diffused in from another culture. The specific trait may be rejected, but the underlying concept is accepted. The concept is often rejected for cultural reasons. This diffusion occurs when an idea or product aren’t being completely diffused throughout the population. Also, this it is when the basic idea or trend is being diffused, but not the exact idea or trend is spread because of the region it spread to. An example of this would be McDonald’s diffusing to India. This is because Hindus don’t eat cows because they believe they are holy, so they replace the meat in the burgers and make them veggie burgers.

Relocation Diffusion
Relocation diffusion is the spread of an idea through physical movement of people from one place to another. Also, it’s movement of individuals who carry an idea or innovation with them to a new, perhaps distant locale. This is caused when people migrate from place to place and bring their culture with them. This is the cause for many different languages being in one area, such as the United States. Not only is language is diffused, but religion and ethnicity as well. An example of this would be the spread of AIDs. This is because it was an outbreak in one area and a person in that area moved to another and continued to spread it.