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Science, engineering and technology

The distinction between science, engineering and technology is not always clear. Science is the reasoned investigation or study of phenomena, aimed at discovering enduring principles among elements of the phenomenal world by employing formal techniques such as the scientific method. Technologies are not usually exclusively products of science, because they have to satisfy requirements such as utility, usability and safety.

Engineering is the goal-oriented of designing and making tools and systems to exploit natural phenomena for practical human means, often (but not always) using results and techniques from science. The development of technology may draw upon many fields of knowledge, including scientific, engineering, mathematical,linguistic and historical knowledge, to achieve some practical result.

Technology is often a consequence of science and engineering — although technology as a human activity precedes the two fields. For example, science might study the flow of electrons in electrical conductors , by using already-existing tools and knowledge. This new-found knowledge may then be used by engineers to create new tools and machines, such as semiconductors, computers, and other forms of advanced technology. In this sense, scientists and engineers may both be considered technologists; the three fields are often considered as one for the purposes of research and reference.

The exact relations between science and technology in particular have been debated by scientists, historians, and policymakers in the late 20Th century, in part because the debate can inform the funding of basic and applied science. In immediate wake of World War II , for example, in the United States it was widely considered that technology was simply "applied science" and that to fund basic science was to reap technological results in due time.

Science:

• A body of knowledge
• Seeks to describe and understand the natural world and its physical properties
• Scientific knowledge can be used to make predictions
• Science uses a process--the scientific method--to generate knowledge

Engineering:

• Design under constraint
• Seeks solutions for societal problems and needs
• Aims to produce the best solution given resources and constraints
• Engineering uses a process--the engineering design process--to produce solutions and technologies

Technology:

• The body of knowledge, processes, and artifacts that result from engineering
• Almost everything made by humans to solve a need is a technology
• Examples of technology include pencils, shoes, cell phones, and processes to treat water

In the real world, these disciplines are closely connected. Scientists often use technologies created by engineers to conduct their research. In turn, engineers often use knowledge developed by scientists to inform the design of the technologies they create.

Science, engineering, and technology are all situated in a larger society that determines what science and engineering get done. Human values, needs, and problems determine in large part what questions scientists investigate and what problems engineers tackle. In turn, the technological products of science and engineering influence society and change human culture.

Technology

Technology deals with human as well as other animal species' usage and knowledge of tools crafts, and how it affects a species' ability to control and adapt to its natural environment. The word technology comes from the Greek technología — téchnē , 'craft' and the study of something, or the branch of knowledge of a discipline. A strict definition is elusive; technology can be material objects of use to humanity, such as machine, but can also encompass broader themes, including systems, methods of organization, and techniques. The term can either be applied generally or to specific areas: examples include "construction technology", "medical technology", or "state of the art technology".

The human species' use of technology began with the conversion of natural resources into simple tools. The prehistorical discovery of the ability to control fire increased the available sources of food and the invention of the wheel helped humans in travelling in and controlling their environment. Recent technological developments, including the printing press, the telephone, and the Internet, have lessened physical barriers to communication and allowed humans to interact freely on a global scale. However, not all technology has been used for peaceful purposes; the development of weapons ever-increasing destructive power has progressed throughout history, from clubs to nuclear weapons.

Technology has affected society and its surroundings in a number of ways. In many societies, technology has helped develop more advanced economies (including today's global economies) and has allowed the rise of a leisure class. Many technological processes produce unwanted by-products, known as pollution, and deplete natural resources, to the detriment of the Earth and its Environment. Various implementations of technology influence the values of a society and new technology often raises new ethical questions. Examples include the rise of the notion of efficiency in terms of human productivity, a term originally applied only to machines, and the challenge of traditional norms.

DIFFERENT SOURCE OF SOLAR ENERGY

While I have wandered from the main subject of the sun, to consider the source of stellar energy, the two topics are so intimately related that their solutions are identical. I consider that I have demonstrated the reasonableness of Jeans's theory by the manner in which it seems to fit the observed facts. There is, as I can see, no important objection to the hypothesis. It is too much to hope that the foregoing analysis is rigidly complete, but I confidently believe that the main points are established and that further modification will consist in the clearing up of details. The application of astrophysics and atomic theory to a new field appears to have met with considerable success. In spite of this success, however, caution is necessary. The present position of the theory advocated in this paper is somewhat analogous to the place once held by the theory of Helmholtz—i.e., it is the only one sufficiently elastic to stretch over the region of known facts. Our knowledge is yet limited and, with our vision thus impaired, we can not predict the future. Some unforeseen event may upset our present hypothesis as completely as that of Helmholtz; we have built as securely as possible upon observation, and it remains for the future to test the accuracy of this or any other theory so established.

In an attempt to discover a reasonable explanation of the origin and duration of the solar radiation, all possible sources of energy are examined. The following hypotheses are reviewed and discarded, the arguments against their validity being too well known to necessitate a review at this place;

(1) Original Heat;

(2) Chemical;

(3) Gravitational,

(a) Meteoric, (b) Contraction;

(4) Radioactive.

THE SOURCE OF SOLAR ENERGY

The source of all energy radiated by the Sun lies in its core, a central region comprising only 1.5% of the total solar volume. This is a very large thermonuclear reactor where Hydrogen atoms are fused together to form Helium, releasing energy at the rate of 3.86 x 1026 Joules per second. The fusion reactions in the solar core take place because of the very high temperatures and very large pressures present in this region of the Sun. Although there is no way of measuring these quantities directly, physical models of the Sun suggest that the core temperature is around 15 million degrees and the central pressure is about 250 billion atmospheres (250 billion times the pressure on the Earth at sea level).
It is the massive gravity of the Sun that compresses the core to such a high pressure and resultant high temperature, which then is sufficient to ignite the fusion reactions which take place. The overall result is to convert 4 Hydrogen atoms into one Helium atom (see below). For every 1 kilogram of hydrogen that is consumed, most is turned into Helium but a small portion, 0.007 kg, is turned into pure energy. Using the famous energy-mass equivalence formula (E = m c2) developed by Einstein, we can calculate that this mass amounts to a little over 600 trillion Joules (6 x 1014 J). When related to the total energy output of the Sun, this means that the solar fusion reactions are consuming mass at almost 5 million tons per second!
There are two distinct reactions in which 4 H atoms may eventually result in one He atom. The first of these is:
(1) 1H + 1H → 2D + e+ + ν
then 2D + 1H → 3He + γ
then 3He + 3He → 4He + 1H + 1H
This reaction sequence is believed to be the most important one in the solar core. The total energy released by these reactions in turning 4 Hydrogen atoms into 1 Helium atom is 26.7 MeV.
The second reaction generate less than 10% of the total solar energy. This involves carbon atoms which are not consumed in the overall process. The details of this "carbon cycle" are as follows:
(2) 12C + 1H → 13N + γ then 13N → 13C + e+ + ν then 13C + 1H → 14N + γ
then 14N + 1H → 15O + γ then 15O → 15N + e+ + ν
then 15N + 1H → 12C + 4He + γ
All the energy that is generated in the solar core escapes mostly in the form of very high energy gamma rays. This energy is absorbed and re-emitted many many times by the layers overlying the core, as the photons (bits of electromagnetic energy) diffuse out toward the surface. In doing so, the energy is degraded; gamma photons are turned into X-ray photons, and then into UV photons, and finally into visible light and infrared photons. And so it is light and heat that is finally radiated from the surface of the Sun into interplanetary space. This same heat and light has a flux density of 1370 watts per square metre by the time it arrives at the upper atmosphere of the Earth. It is this energy that makes life possible on the surface of the Earth, that produces our terrestrial weather, and that photovoltaic cells can convert into electrical energy. Solar energy is, in actuality, nuclear energy.

Solar water heating

Solar water heating, where heat from the Sun is used to heat water in glass panels on your roof. This means you don't need to use so much gas or electricity to heat your water at home. Water is pumped through pipes in the panel. The pipes are painted black, so they get hotter when the Sun shines on them. The water is pumped in at the bottom so that convection helps the flow of hot water out of the top.

This helps out your central heating system, and cuts your fuel bills. However, with the basic type of panel shown in the diagram you must drain the water out to stop the panels freezing in the winter. Some manufacturers have systems that do this automatically. Solar water heating is easily worthwhile in places like California and Australia, where you get lots of sunshine.