Principle Definition and 1000 Threads

A principle is a proposition or value that is a guide for behavior or evaluation. In law, it is a rule that has to be or usually is to be followed. It can be desirably followed, or it can be an inevitable consequence of something, such as the laws observed in nature or the way that a system is constructed. The principles of such a system are understood by its users as the essential characteristics of the system, or reflecting system's designed purpose, and the effective operation or use of which would be impossible if any one of the principles was to be ignored. A system may be explicitly based on and implemented from a document of principles as was done in IBM's 360/370 Principles of Operation.
Examples of principles are, entropy in a number of fields, least action in physics, those in descriptive comprehensive and fundamental law: doctrines or assumptions forming normative rules of conduct, separation of church and state in statecraft, the central dogma of molecular biology, fairness in ethics, etc.
In common English, it is a substantive and collective term referring to rule governance, the absence of which, being "unprincipled", is considered a character defect. It may also be used to declare that a reality has diverged from some ideal or norm as when something is said to be true only "in principle" but not in fact.

View More On Wikipedia.org
Recent contents Top users
  1. S

    Does Lawrence Krauss believe in the anthropic principle?

    Summary: Does Lawrence Krauss believe in the anthropic principle? I have read a lot of texts both indicating that physicist Lawrence Krauss is against the anthropic principle. But I have read several texts indicating that Lawrence Krauss believes that this principle is true and has developed...
  2. T

    Uncovering the Motivation behind the Principle of Virtual Work

    Hello May I ask: "What is the guiding philosophy of the Principle of Virtual Work?" I do understand it an how to use it, in classical mechanics. (And I will openly admit that I do not entirely understand what I am looking for, or what I am asking.) But what is happening at this moment in...
  3. S

    Least Upper Bound Property ⇒ Archimedean Principle

    Hello! I was wondering if this proof was correct? Thanks in advance! Given: A totally ordered field, ##\mathbb{F}##. Claim: Least Upper Bound Property (l.u.b.) ⇒ Archimedean Principle (AP) --- Proof. I will show that the contrapositive is true; that is, if ##\mathbb{F}## does not have the AP...
  4. F

    I Huygen’s Principle in 2 Dimensions

    I’ve seen posts similar to this one, but I’m still struggling to understand this concept. Huygen’s principle is only valid with an odd number of spatial dimensions, yet it is often taught with the visual aid of 2 dimensional water waves. So why doesn’t Huygen’s principle apply in 2...
  5. S

    I Does the Strong Anthropic Principle have any equivalent specific model?

    The anthropic principle is a philosophical consideration that observations of the universe must be compatible with the conscious and sapient life that observes it. There are two main types of anthropic principle: Weak Anthropic Principle (WAP) and Strong Anthropic Principle (SAP) The Strong...
  6. W

    Bernoulli's Principle -- correct derivation

    In this scenario I'm assuming that there is a shared velocity of water within the pipes, as well as a shared pressure and that water is non-compressible. If I understand correctly when someone says that pressure at a point is P at some point, it is the same as saying that if I put a small cube...
  7. R

    Reverse reactions and Le Chateliers principle

    In acid-base reactions, the reaction never goes 100% toward the product, right? A reverse reaction will occur and eventually reaction toward product and reactant will reach equilibrium. In lab/industry conditions where yield is important, how does they push the reaction toward product? I am...
  8. Andy_K

    B Quantum Wave & Principle of Least Action

    Dear All, I would like to better understand how the Principle of Least Action applies in observations / measurements in quantum physics. Does the wave function of a particle correspond directly to the principle of least action, as in, the positions with higher probability of detecting the...
  9. S

    I Is the holographic principle based on fuzzy logic?

    Physicist Craig Hogan has proposed that the universe is based on holographic principle. To prove that the universe is a "hologram" he (and other physicists) have designed an experiment named "The Holometer" to measure quantum fluctuations that would become fuzzy at Planck scale...
  10. R

    I Hund's rules and Pauli's principle

    So as I can see from the literature there are two "methods" on how to apply Hund's rules to determine the ground state of an electron configuration. Method 1: One determines all possible states due to Pauli's principle (wave function must be totally antisymmetric) using angular momentum...
  11. clergy

    Fluids using Bernoullis principle

    Please help!
  12. W

    I Uncertainty Principle in the context of tracking particle paths

    I have a bit of confusion regarding the application of the uncertainty principle in the context of experiments. If a detector allows you to measure a particle's path through said detector, does that mean that you know a particle's position at all points in time, and are able to work out its...
  13. S

    A How does this study affect the holographic principle?

    In a recent study (https://phys.org/news/2018-08-flaw-emergent-gravity.html) it has been discovered an important flaw in Emergent/Entropic Gravity because it has been discovered that holographic screens cannot behave according to thermodynamics... But then, doesn't this also invalidate...
  14. E

    I About the Feynman Path Integral and Principle of Least Time

    I don't entirely get why we usually say that only the shortest path contributes in the path integral. If you calculate the volume of nth fresnel zones which is the locus where the path length is between n-1 and n wavelengths from the shortest path in 3 dimensions, they are the same I believe. So...
  15. J

    I Classicality and the Correspondence Principle

    Correspondence Principle states that the behavior of systems described by the theory of quantum mechanics (or by the old quantum theory) reproduces classical physics in the limit of large quantum numbers. In other words, it says that for large orbits and for large energies, quantum calculations...
  16. B

    B Measuring a circle and the Uncertainty principle

    I have been trying to see if my understanding of uncertainty principle is right. So I thought consider a circle. for this augment we will look at its diameter and it circumference. Suppose you get a length of string and make a exact measure of the circles circumference using this length of...
  17. D

    B Heisenberg's uncertainty principle - does it always apply?

    I am not too knowledgeable about QM, so please forgive me if this is a dumb question. I have outlined below an experiment setup for which Heisenberg's uncertainty principle seems not to apply: Imagine a particle for which we wish to collect the exact position and velocity. We have a detector d1...
  18. J

    A Can the Huygens-Fresnel principle be translated into path integrals?

    Wave optics, including diffraction, seems to be apt for path integral language. In fact, Feynman's double slit language is purely "diffraction". Also, the PDE for the wave equation results in a solution via Green's function, and the Green function is where "the path integral lives". I have...
  19. B

    I How does the Pauli exclusion principle work?

    Hello! I am a bit confused about the mechanism behind the Pauli exclusion principle. From what I read, it is motivated based on QFT arguments (for example if you don't impose antisymmetry of the fermionic wavefunction you get non-locality, or infinitely negative energies etc.) so mathematically...
  20. E

    How do adapters work? (SATA to USB, or VGA to HDMI)

    Does adapters (exp: SATA to USB or VGA to hdmi) work with special softwares for conversion or are they only electronic circuits which gets and directs input signals to correct output pins?
  21. J

    I Pauli exclusion principle and Hermitian operators

    http://vergil.chemistry.gatech.edu/notes/quantrev/node20.html "Postulate 2. To every observable in classical mechanics there corresponds a linear, Hermitian operator in quantum mechanics. " "Postulate 6. The total wavefunction must be antisymmetric with respect to the interchange of all...
  22. fluidistic

    A Non interacting Fermions satisfy the Pauli exclusion principle

    This question is more a question I'd ask in a chat rather than formally on paper/forum. If we take the free electron model, the electrons are considered as non interacting. It is essentially a 1 particle problem where the potential is constant through space. The electrons are not perturbed at...
  23. J

    A Is there a principle of stationary action for QFT?

    Classical mechanics (and classical field theory) has the principle of stationary action (Hamilton's principle) as main principle. The Euler-Lagrange equations are derived from that principle, by using calculus of variations, on functionals (functions of functions). Is there an equivalent...
  24. F

    Huygens' Principle for Sound Waves

    I have a basic understanding of Huygens principle, but I don't quite understand why sound waves follow huygens principle. When sound travels, particles travel back and fourth in one direction, so how do sound waves end up traveling in all directions after traveling through a slit? Do sound...
  25. F

    Can light always be treated as a physical object?

    My understanding of light has been that it travels in a perfectly straight line unless reflected or refracted by some object. Treating light like physical objects (like pool balls bouncing off the sides of a table) has been useful for situations where geometry can be used to find things like...
  26. Bure

    A The uncertainty principle in quantum gravity

    The main role in quantum gravity can be played by the uncertainty principle , where is the gravitational radius, is the radial coordinate, is the Planck length. This uncertainty principle is another form of Heisenberg's uncertainty principle between momentum and coordinate as applied to the...
  27. T

    Question about the moment/torque principle

    Hi. We all know that example where they show you a balancing lever on a fulcrum, with 2 weights on each side. And you have the equation F1L1=F2L2. (F=force, L= distance) But my question is different... Does the total weight of the lever applied on the fulcrum changes with the distance of the...
  28. T

    Bernoulli Principle from a molecular scale

    Good evening everyone. Can you tell me if it is possible to mathematically derive the Bernoulli principle from a microscopic analysis? In particular, in the hypothesis of an incompressible stationary flow, at a constant altitude, it states that: P + 0.5ρV^2 = cost Well, in textbooks this...
  29. wrobel

    Insights A Pure Hamiltonian Proof of the Maupertuis Principle - Comments

    Greg Bernhardt submitted a new blog post A Pure Hamiltonian Proof of the Maupertuis Principle Continue reading the Original Blog Post.
  30. LarryS

    Principle of Least Action for optics?

    Fermat's Principle states that light always travels the path of least time. In Classical Physics, other than the above, is there a separate "Principle of Lease Action" for light? Thanks in advance.
  31. D

    I Requesting help with the uncertainty principle equation

    Hi For 2 Hermitian operators A and B using the Cauchy-Schwarz inequality and assuming the expectation values of A and B are zero I get (ΔA)2(ΔB)2 ≥ (1/4)|<(AB+BA)>|2 + (1/4)|<(AB-BA)>|2 Now both terms on the RHS are positive so why is this inequality usually just written with only the...
  32. J

    I Feynman-Heaviside formula and Mach's principle

    I was wondering if the [Feynman-Heaviside formula](http://www.feynmanlectures.caltech.edu/II_21.html) for the electric field of a moving charge could be used to write down the force/reaction force between charges ##q_1## and ##q_2## in a Machian purely relational way. The retarded electric...
  33. Radhika Ahuja

    What are the key mistakes in approaching this work-energy principle problem?

    Homework Statement : A skater with mass 70kg standing on ice throws a stone of mass 5kg with a velocity of 8m/s in the horizontal direction. Find the distance over which the skater will move back if the coeffcient of friction between the skates and the ice is 0.02[/B]Homework EquationsThe...
  34. Geofleur

    A Pathological example of a Principle Fiber Bundle?

    In Hassani's Mathematical Physics, a principal fiber bundle is defined as shown below. I wanted to see if there is a way to view a tangent bundle as a PFB, even if the resulting structure would have to be globally trivial, so I came up with this idea: Let ##P = {\rm I\!R} \times {\rm l\!R}##...
  35. TachyonLord

    B Whats the principle behind Schuster Focusing?

    I know its something related to the asymmentry in the i-d curve but its still not clear.
  36. P

    I Electrons and the Pauli exclusion principle

    electrons are repelled using the Pauli exclusion principle?
  37. solarmidnightrose

    Bernoulli Principle vs. Coanda Effect

    In the past couple of days I've been watching video demonstrations on YouTube that use the Bernoulli Principle to explain what is happening (e.g. the hairdryer and ball experiment) Then, I saw this one video using the Coanda Effect as the explanation (they were also using the hairdryer and ball...
  38. A

    A Uncertainty principle, removing infinity in the Fourier Transform

    I have come across a paper where it is stated that if the infinity assumption in the FT is removed, the uncertainty doesn't hold. Is this a sensible argument? Thank you.
  39. fando1234

    I What does Fermat's principle of least time mean for causality

    I have been reading some fairly mind bending stuff about the principle or least time (and those of least action) raising questions about causality and free will. Can anyone explain this to me? Is this total 'woo woo' psuedo science, or are these philosophical questions widely accepted? Thanks...
  40. J

    I Falling electric dipole contradicts the equivalence principle?

    Consider an electric dipole consisting of charges ##q## and ##-q##, both of mass ##m##, separated by a distance ##d##. If the dipole is given an acceleration ##a## perpendicular to its moment the total electric force on it, due to each charge acting on the other, is given approximately by...
  41. Y

    Le Chatelier's Principle: Equilibrium Shift with Pressure Change

    Homework Statement Homework Equations - The Attempt at a Solution I know that the equilibrium will shift to the side with fewer moles of molecules when the pressure is increased according to le Chatelier's principle, so I thought in this case it would shift to the left as there is only 1...
  42. alijan kk

    Find the resultant using the principle of moments

    Homework Statement Homework EquationsThe Attempt at a Solution problem number 10
  43. S

    I The Uncertainty Principle - question within Griffiths' Text

    Hello, In Griffiths (2nd edition) pgs 110-111 - deriving the uncertainty principle I have 2 questions 1) I am stuck on a point ... (h = ^ hat ) <f | g > = < ( Ah - <A>) ψ | ( Bh - <B>) ψ > = <Ψ | ( Ah - <A>) ( Bh - <B>) Ψ> FOIL = <ψ | AhBh ψ> - <B><ψ | Ah ψ> - <A>< ψ | Bh ψ> +...
  44. A

    I Calculating the resolution limit using Fermat's principle

    Hi, I read the Feynman Lectures Volume 1, Chapter 27, section 27-7, which can be here. In the lecture he describes the fundamental limits of resolution and provides a criterion. Here is the diagram I am referring to, figure 27.-9: There are two light sources, ##P## and ##P'## There is an...
  45. bland

    I Accuracy of time dilation measurement *in principle*

    Sorry that's the best wording for a title I could come up with. Anyhoo my question is one that I have wondered about for a long time, and I am prompted to post now after seeing this article on the new atomic clock. Let's assume that we have clocks that can measure time to an arbitrarily...
  46. S

    Using the angular momentum principle for 2 pucks

    Homework Statement Two pucks are lying on ice where they can slide and rotate with almost no friction. A string is tied to both pucks but it is tied to the middle of the first puck and wrapped around the second puck. You pull on both strings with the same force, F. The first puck moves without...
  47. L

    Buouyancy force and Archimedes' principle

    How much more will the volume of a fishingboat go under water, if I load the boat with 3.0m^3 fish with the density 0.90kg/dm^3? Fish : 3.0m^3 Density of fish: 0.90kg/dm^3? Homework Equations Archimedes principle: density * volume * g[/B]The Attempt at a Solution Tried setting upward force...
  48. QuasarBoy543298

    I Variation principle - holonomic constraints

    in order to extend hamilton's principle to include holonomic constraints, out lecturer did the following : when we are under constraints, we cannot consider the variations of the coordinates as independent of each other. we know that the constraint equations are fa = 0. we can multiply each...
  49. M

    I Photons and Heisenberg's Uncertainty Principle

    To summarize, my current understanding of how Heisenberg's uncertainty principal works suggests that there would be a contradiction (somewhere down the line) with any way that it applies to (or doesn't apply to) photons, due to the fact that they must always travel the speed of light. I...
  50. Umaxo

    I Limits of the variatonal principle

    Hi, I got curious on the limits of variatonal principle. As far as i know all of the theories can be reformulated as problem of finding extremum of some action. Not only that, but it seems to be most convenient method for looking for new theories in a lot of cases. So my question is, what are...
Back
Top