Science (from Latin scientia - knowledge) refers to a system of acquiring knowledge - based on empiricism, observation, experimentation, and methodological naturalism - aimed at finding out the truth. The basic unit of knowledge is the theory, which is a hypothesis that is predictive. The term science also refers to the organized body of knowledge humans have gained by such research. A scientist is a person whose work or career involves science.

Most scientists feel that scientific investigation must adhere to the scientific method, a process for evaluating empirical knowledge under the working assumption of methodological materialism, which explains observable events in nature by natural causes without assuming the existence or non-existence of the supernatural. Less formally, the word science often describes any systematic field of study or the knowledge gained from it. Particular specialized studies that make use of empirical methods are often referred to as sciences as well. This article concentrates on the more specific definition.

Science as defined above is sometimes termed pure science or fundamental science to differentiate it from applied science.

Applied science is applying knowledge from one or more natural scientific fields to practical problems. It is closely related or identical to engineering.

General types of science[]

Of course, science can be categorized into pure science or applied science as described above. Another way of categorizing science is to divide it into the general fields of natural science or social science. Social science has to do with how people behave or interact. Natural science covers science outside of the area of social science and is concerned with how matter, materials, energy, and other living organisms behave, although natural science also covers how things work inside the human body. In other words, natural science is concerned with how nature works. Natural science can be further broadly categorized into physical science or life science. Life science is concerned with living organisms including how things work inside the human body, whereas physical science is generally concerned with non-living things such as matter, materials, energy, etc. In any event, these distinctions are often rather artificial and arbitrary, and there is much overlap between these general areas and in the slightly more specific areas discussed below.

Examples of physical sciences include:

  • physics (practitioner called a physicist)
Example sub-areas of physics include:
  • chemistry (practitioner called a chemist)
  • geology (practitioner called a geologist)
  • material science - basically involves physical and chemical study of materials, sometimes neglected by mainstream physicists and chemists
Example sub-areas of material science include:
  • metallurgy (practitioner called a metallurgist)
  • ceramics
  • polymer science which particularly involves a lot of chemistry

Examples of life science include:

  • biology (practitioner called a biologist)
  • health science, the practice of which can be referred to as medicine

Examples of social science include:

  • psychology (practitioner called a psycologist)
  • sociology (practitioner called a sociologist)

Examples of how the above areas of science can overlap include the fields of biochemistry, biophysics, and physical chemistry (chemical physics).

Perhaps most closely related to mathematics is:

Engineering and Science[]

You see things; and you say "Why?" But I dream things that never were; and I say "Why not?"
—George Bernard Shaw

Engineering is concerned with the design of a solution to a practical problem. A scientist may ask why a problem arises, and proceed to research the answer to the question or actually solve the problem in his first try, perhaps creating a mathematical model of his observations. By contrast, engineers want to know how to solve a problem, and how to implement that solution. In other words, scientists attempt to explain phenomena, whereas engineers use any available knowledge, including that produced by science, to construct solutions to problems. This is no contradiction.

There is an overlap between science (fundamental and applied) and engineering. It is not uncommon for scientists to become involved in the practical application of their discoveries; thereby becoming, for the moment, engineers. Scientists may also have to complete engineering tasks, such as designing experimental apparatus or building prototypes. Conversely in the process of developing technology, engineers sometimes find themselves exploring new phenomena, thus becoming, for the moment, scientists.

In many cases, types of engineering may be closely related to fields of science, for example:

  • Chemical engineering and chemistry
    • Biochemical engineering and biochemistry can be thought of as subsets to the above.
  • Bioengineering and biology
  • Computer engineering and computer science are very closely related.
  • Materials engineering is very closely related to material science, such that one can say they are almost the same
    • Metallurgical engineering and metallurgy are very closely related and can be thought of as subsets to the above.
    • Ceramic engineering and the science of ceramics are also very closely related and can be thought of as subsets to the above.
    • Polymer engineering and polymer science are very closely related and can be thought of as subsets to the above.

In physics:

However, engineering research has a character different from that of scientific research. First, it often deals with areas in which the basic physics and/or chemistry are well understood, but the problems themselves are too complex to solve in an exact manner. The purpose of engineering research is then to find approximations to the problem that can be solved. Examples are the use of numerical approximations to the Navier-Stokes equations to solve aerodynamic flow over an aircraft, or the use of Miner's rule to calculate fatigue damage to an engineering structure. Second, engineering research employs many semi-empirical methods that are foreign to pure scientific research, one example being the method of parameter variation.

In general, it can be stated that a scientist builds in order to learn, but an engineer learns in order to build.

The main exception to calling the application of science to be engineering is for practitioners of applied health science, which are called physicians or medical doctors when treating humans or veteranarians when treating animals. They are not called engineers. However, they often use equipment designed by bioengineers or biomedical engineers.