A Principle in physics is a statement of the limits of intrinsic natural properties. It is different from a Law because it is not a statement of one type of observation but rather a statement of the patterns governing Laws and Theories. A Principle is a powerful statement; it can never be ignored; there are absolutely no exceptions to a Principle. A Rule can be ignored easily by changing conventions. A Theory can have exceptions, which often may indicate that the theory is incomplete but they won't necessarily disprove it.
A Law cannot be ignored or have exceptions within the limits established by the Principles of Nature remember, they are statements of nature's limits. Outside of these limits, all Laws are subject to the "Law of Exceptions" - every law has exceptions, no exceptions.
For example, consider the Heisenberg Uncertainty Principle. It describes the limits on the amount of information one can have about something. Within this limit, the Laws are immutable, however, if you consider for example distances or time scales less than the Heisenberg limit, processes that violate the Law of Conservation of Energy are allowed. It is only Principles that may never have exceptions. A Principle is usually of the form "All natural systems are subject to Given limits with respect to Given intrinsic property ".
The definition I gave for a Principle might seem a bit iffy. Let me clarify, an intrinsic natural property is not a direct observable; examples are the amount of information about a system, the Action of a process, etc. To state the principle of least action in the form I identified; "All natural systems are subject to a minimization with respect to the Action of that system ".
Having said all this, I realize I promised a brief answer It seems I failed at that. However, when explaining to someone else, it should suffice to take the first sentence of each of the 4 defining paragraphs. Hope this helps. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group.
Create a free Team What is Teams? Learn more. What sets a "Law" apart from a "Rule" or a "Principle"? Asked 8 years, 4 months ago. Active 2 years, 6 months ago. Viewed 15k times. Improve this question. Read more comments. Arabic English US Near fluent. See a translation. Highly-rated answerer. Rule- norm of behavior, an understood regulation. Law- a rule that government has made and citizens under the government must follow. Legal rule. Principle- fundamental idea, base of belief Principles are the reason we have rules and laws.
Ex: 1. Freedom of speech is a constitutional law. This fundamental feature of physical phenomena makes it a universalized law. Newton's third law illustrates these features as well. Newton's third law states that for every action, there is an equal and opposite reaction.
The statement means that in every interaction, there is a pair of forces acting on the two interacting objects. When the sun pulls the planets towards it as they orbit, the planets pull back in response, These laws of physics describe these features of nature as inherent within the universe.
Heisenberg's Uncertainty Principle can be described as "nothing has a definite position, a definite trajectory, or a definite momentum," but it also requires further explanation for clarity.
When physicist Werner Heisenberg tried studying subatomic particles with increased precision, he found it impossible to exactly determine a particle's momentum and position simultaneously. Heisenberg used the German word "Ungenauigkeit," meaning "imprecision" not "uncertainty" to describe this phenomena that we would call the Uncertainty Principle.
The momentum, the product of an object's velocity and mass, and position are always at a tradeoff between one another. The original German word describes the phenomena more accurately than the word "uncertainty" does. The Uncertainty Principle adds uncertainty to observations based on the imprecision of a physicist's scientific measurements. Because these principles depend highly on the context and conditions of the principle, they are more like guiding theories used to make predictions about the universe phenomena than laws are.
If a physicist studied the motion of an electron in a large box, she could get a fairly accurate idea of how it would travel throughout the box.
But if the box were made smaller and smaller such that the electron couldn't move, we would know more about where the electron is, but know much less about how fast it was traveling. For objects in our every day life, such as a moving car, you can determine the momentum and position, but there would still be a very small amount of uncertainty with these measurements because the uncertainties are much more significant for particles than everyday objects.
While laws and principles describe these two different ideas across physics, biology and other disciplines, theories are collections of concepts, laws and ideas to explain observations of the universe. The theory of evolution and the the general theory of relativity describe how species have changed over generations and how massive objects distort space-time through gravity, respectively.
In mathematics, researchers can refer to theorems , mathematical claims that can be proven or disproven, and lemmas , less important results usually used as steps to prove theorems. The Pythagorean theorem depends on the geometry of a right triangle to determine the length of their sides.
It can be proven mathematically. Other terms may not be as clear. The difference between a rule and a principle may be debated, but rules generally refer to how to determine the correct answer from different possibilities.
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