Give an example of scientific theory?

Answer 1

Lay people often misinterpret the language used by scientists. And for that reason, they sometimes draw the wrong conclusions as to what the scientific terms mean.

Three such terms that are often used interchangeably are "scientific law," "hypothesis," and "theory."

In layman's terms, if something is said to be "just a theory," it usually means that it is a mere guess, or is unproved. It might even lack credibility. But in scientific terms, a theory implies that something has been proven and is generally accepted as being true.

Here is what each of these terms means to a scientist:

Scientific Law: This is a statement of fact meant to describe, in concise terms, an action or set of actions. It is generally accepted to be true and universal, and can sometimes be expressed in terms of a single mathematical equation. Scientific laws are similar to mathematical postulates. They don't really need any complex external proofs; they are accepted at face value based upon the fact that they have always been observed to be true.

Specifically, scientific laws must be simple, true, universal, and absolute. They represent the cornerstone of scientific discovery, because if a law ever did not apply, then all science based upon that law would collapse.

Some scientific laws, or laws of nature, include the law of gravity, Newton's laws of motion, the laws of thermodynamics, Boyle's law of gases, the law of conservation of mass and energy, and Hook's law of elasticity.

Hypothesis: This is an educated guess based upon observation. It is a rational explanation of a single event or phenomenon based upon what is observed, but which has not been proved. Most hypotheses can be supported or refuted by experimentation or continued observation.

Theory: A theory is more like a scientific law

than a hypothesis. A theory is an explanation of a set of related observations or events based upon proven hypotheses and verified multiple times by detached groups of researchers. One scientist cannot create a theory; he can only create a hypothesis.

In general, both a scientific theory and a scientific law are accepted to be true by the scientific community as a whole. Both are used to make predictions of events. Both are used to advance technology.

In fact, some laws, such as the law of gravity, can also be theories when taken more generally. The law of gravity is expressed as a single mathematical expression and is presumed to be true all over the universe and all through time. Without such an assumption, we can do no science based on gravity's effects. But from the law, we derived the theory of gravity which describes how gravity works, what causes it, and how it behaves. We also use that to develop another theory, Einstein's General Theory of Relativity, in which gravity plays a crucial role. The basic law is intact, but the theory expands it to include various and complex situations involving space and time.

The biggest difference between a law and a theory is that a theory is much more complex and dynamic. A law describes a single action, whereas a theory explains an entire group of related phenomena.

An analogy can be made using a slingshot and an automobile.

A scientific law is like a slingshot. A slingshot has but one moving part--the rubber band. If you put a rock in it and draw it back, the rock will fly out at a predictable speed, depending upon the distance the band is drawn back.

An automobile has many moving parts, all working in unison to perform the chore of transporting someone from one point to another point. An automobile is a complex piece of machinery. Sometimes, improvements are made to one or more component parts. A new set of spark plugs that are composed of a better alloy that can withstand heat better, for example, might replace the existing set. But the function of the automobile as a whole remains unchanged.

A theory is like the automobile. Components of it can be changed or improved upon, without changing the overall truth of the theory as a whole.

Some scientific theories include the theory of evolution, the theory of relativity, the atomic theory, and the quantum theory. All of these theories are well documented and proved beyond reasonable doubt. Yet scientists continue to tinker with the component hypotheses of each theory in an attempt to make them more elegant and concise, or to make them more all-encompassing. Theories can be tweaked, but they are seldom, if ever, entirely replaced.

A theory is developed only through the scientific method, meaning it is the final result of a series of rigorous processes. Note that theories do not become laws. Scientific laws must exist prior to the start of using the scientific method because, as stated earlier, laws are the foundation for all science. Here is an oversimplified example of the development of a scientific theory:

To answer your question here is a theory Darwin's theory of natural selection

If evolution was a car, the theory of natural selection would be the engine. The basic ideas of evolution were discussed long before there was any scientific research done to support them. The evolutionary concept was never able to gain any real steam because it lacked a mechanism. That is, scientists wanted to believe that species evolved from one form to another, but had no plausible process to make it happen. The theory of natural selection provides that reasonable method of evolution.

Natural selection essentially states that "the strong survive." The basic idea is that when change occurs, those organisms best suited to the new circumstances will thrive. Those who are not ideally suited will not be able to compete. Charles Darwin proposed this principle after observing some population variations in birds. He noticed that animals within a species often had slightly varied traits, and that those traits made some more suited to certain conditions. Darwin's theory was that, over time, the better suited animals would thrive and the others would die out completely. The resulting population would be entirely made up of those animals with the "better" trait. Over time, he reasoned, this could result in a species changing enough traits to eventually become a totally different creature, like a fish becoming a frog.

There have been some concerns expressed about the real meanings of the theory of natural selection. There is no doubt that variations within a single species make some members better suited to handle different circumstances. For instance, there's a popular story in science texts about moths. These moths lived in cities around the time of the industrial revolution and had to deal with increased pollution. Lighter-colored moths stood out on soot-stained buildings and trees, and thus, were easier targets for birds. The darker moths found it easier to survive, because they blended into the darkened environment. As a result, the population of light-colored moths dwindled over time, and the darker-colored moths increased. The dominance of the darker moths is used as an example of natural selection.

There is an important point to be made about the theory of natural selection, however. Once conditions return to "normal," the balance of that species will return to "normal" as well. Birds with unusually heavy beaks may become dominant during dry years, since they can more easily break open nut shells and tree bark. The "normal" birds, with regular beaks, will struggle and diminish. Yet, once the drought is over, the population tends back to normal-beaked birds. The darker moths who were more suited to the polluted times made up most of the moth population, but when the pollution began to fade, the moth population returned to its "normal" state.

Why does this happen? Species have shown to be genetically stable. In fact, genetic defects that change the form or function of creatures usually result in death. The examples of the moths and birds show that each species has some variations, and that those variations can favor different animals at different times. However, they also show that the same variations are possible generation after generation - which is why the populations can change right back to where they were. There are no new species or new variations being produced, just more or less of those that already existed.

There has been no scientific observation of any permanent change in species. There are plenty of proven cases of adaptation, which involves non-genetic changes. There are examples of natural selection changing the balance of populations within a species. Yet there are no known instances of a natural population experiencing a permanent, meaningful change. Observed genetic mutations are, in the natural world, crippling and usually fatal. While there is no doubt about the short-term function of natural selection, its long-term effects are not fully understood. While scientists prefer to point to the examples of birds and moths as proof of the theory of natural selection, they often refuse to see the same examples as contradictory to evolution itself