What is Analogy: Definition and 152 Discussions

Analogy (from Greek ἀναλογία, analogia, "proportion", from ana- "upon, according to" [also "against", "anew"] + logos "ratio" [also "word, speech, reckoning"]) is a cognitive process of transferring information or meaning from a particular subject (the analog, or source) to another (the target), or a linguistic expression corresponding to such a process. In a narrower sense, analogy is an inference or an argument from one particular to another particular, as opposed to deduction, induction, and abduction, in which at least one of the premises, or the conclusion, is general rather than particular in nature. The term analogy can also refer to the relation between the source and the target themselves, which is often (though not always) a similarity, as in the biological notion of analogy.

Analogy plays a significant role in problem solving, as well as decision making, argumentation, perception, generalization, memory, creativity, invention, prediction, emotion, explanation, conceptualization and communication. It lies behind basic tasks such as the identification of places, objects and people, for example, in face perception and facial recognition systems. It has been argued that analogy is "the core of cognition". Specific analogical language comprises exemplification, comparisons, metaphors, similes, allegories, and parables, but not metonymy. Phrases like and so on, and the like, as if, and the very word like also rely on an analogical understanding by the receiver of a message including them. Analogy is important not only in ordinary language and common sense (where proverbs and idioms give many examples of its application) but also in science, philosophy, law and the humanities. The concepts of association, comparison, correspondence, mathematical and morphological homology, homomorphism, iconicity, isomorphism, metaphor, resemblance, and similarity are closely related to analogy. In cognitive linguistics, the notion of conceptual metaphor may be equivalent to that of analogy. Analogy is also a basis for any comparative arguments as well as experiments whose results are transmitted to objects that have been not under examination (e.g., experiments on rats when results are applied to humans).
Analogy has been studied and discussed since classical antiquity by philosophers, scientists, theologists and lawyers. The last few decades have shown a renewed interest in analogy, most notably in cognitive science.

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  1. S

    I Analogy question for algebraists

    An "analogy question": Polynomials with one variable and coefficients in the field K are to finite dimensional K vector spaces as polynomials in several variables over the field K are to ....? As a teenager, I recall taking tests that had "analogy questions" on them. The format was: Thing A...
  2. S

    I Gravitational analog of electromagnetic force

    Is there a gravitational analog of electromagnetic force? [Apart from the obvious "static" forces, ie electrostatic between fixed charges and gravitational between fixed masses.] I am thinking of the classic situation of a moving charge (or current) creating a magnetic field which then...
  3. Delta2

    B What is the analogy for EM waves traveling in vacuum?

    So, is water for water waves, what is the vacuum for EM waves traveling in vacuum. I know the analogy can't be exactly perfect because water molecules oscillate in the presence of water waves, but in vacuum nothing seems to oscillate? Or the vacuum oscillates in some way? And no I am not trying...
  4. mohamed_a

    I Classical analogy approach to quantum mechanics

    I have read about several approcahes to bypass some classical restrictions to quantum facts such as the electron being in a torus-like shape to avoid ,the greater than speed of light, rotation paradox . Could you recommend websites , sources or books that give good classical analogy to quantum...
  5. R

    I Black Hole Waterfall Analogy & Light Speed

    Recently I have seen a number of General Relativity visualisations that show spacetime flowing towards any mass, similar to water flowing into a sink hole. ScienceClic's video is an example. That model is also used in the "waterfall model" to explain the event horizon of a black hole, as the...
  6. P

    Analogy between EM wave reflection and S-parameters

    It is well known that one can solve incident an reflective wave in homogeneous linear media by matching PDE boundary conditions. In the electrical engineering community, one solves similar problem using smith chart and scattering parameters for 1-dimensional propapation of TEM modes in...
  7. J

    Water analogy in Particle Physics

    There is something unusual about water. Without atmosphere, water can't exist. It's as if water is part of atmosphere. In vacuum, liquid water can't exist. What other things like water where it needs other aspects like atmosphere to exist? And what is the analogy of water in particle physics...
  8. C

    Is this analogy of the electrodes in a battery right?

    In a zinc / copper danielle cell could we say that the Zinc electrode is like a glass of water (water molecules are electrons) The full glass of water reprenst the charge of the zinc electrode and when you try to fill it with more water it overflows (electrons leave the zinc electrode)
  9. S

    I Superposition Analogy: Ceiling Fan Spin Beyond 15,000 RPM

    Thank you to the very helpful forum leaders for their aide in comprehending entangled particle detection last week. With regards to superposition, would an analogy be: (which involves a thought experiment): a ceiling fan, at rest, has four distinct blades with four known positions...
  10. W

    B Struggles with the geometrical analogy

    {Moderators note: thread split from https://www.physicsforums.com/threads/a-geometrical-view-of-time-dilation-and-the-twin-paradox-comments.842793 } I am a novice about relativity, but I found this convoluted and very difficult to follow. I think the lengths in the different coordinate systems...
  11. MichPod

    I Why Not Develop Relativistic Gravitational Theory Analogy to Electromagnetism?

    How can it be easily shown that it's a bad idea to develop relativistic gravitational theory in full analogy with electromagnetism? I.e. why not to introduce 4-potential for gravitation in analogy with 4-potential in covariant form of Maxwell equations and get something fully analogous to...
  12. F

    Polarization of Light Analogy Question

    Homework Statement Hi everyone, I'm a high school teacher and every time I teach the concept of polarization, students ask me the same question and I can't answer it. I show students this picture. The red lines show the electric field vibrations. After passing through polarizer 1, the...
  13. B

    Analogy for Electrical potential

    When the eletctric field was defined I could totally relate to E is like g in mechanics. But for the electric potential I don't know. What would be equivalent analogy?
  14. Souhardya Nandi

    B Balloon Analogy - 3D universe on a 2D plane

    This has been a real famous analogy and I understand it, except the fact that the balloon surface is a 2D structure. How is it possible to depict a 3D universe on a 2D plane ? What happens when we work with stars at multiple planes ?
  15. L

    I Can a Circular Function with Complex Variable Represent a 3D Graph?

    Does a circular function with complex variable represent a three-dimensional graph? For example cosiz
  16. learn.steadfast

    I Classical mass vs. relativistic mass for electronic analogy

    I'm working on semiconductor physics and cyclotrons. There's an article that I am trying to understand, but am having difficulties matching with experiment. I asked a question on an electronics site, but apparently the physics is too advanced. The relativity article which sparked my interest...
  17. M

    I Matrix Mechanics and non-linear least squares analogy?

    I have some experience with non-linear least squares curve fitting. For instance, if I want to fit a Gaussian curve to a set of data, I would use a non-linear least squares technique. A "model" matrix is implemented and combined with the observed data. The solution is found by applying well...
  18. G

    Comparing inductance and capacitance: Analogy to charge

    Hi. Inductance and capacitance have many analogies, both conceptually and formally. A capacitor connected to a voltage source carries the charge ##Q=C\cdot V##. The analogous equation for inductance is ##n\cdot \Phi=L\cdot I##. Charge is physical, it's proportional to the number of excess...
  19. SteveSA

    B Perhaps a silly analogy - hologram light source retreating?

    Hi everyone I would love to get some feedback on this silly idea I had when thinking of the balloon analogy. Another way to achieve the same effect - at least in 2 dimensions - is to move a projector further away from a screen - everything expands relatively. If the universe is a 2d hologram...
  20. D

    Voltage vs Resistance. (Temperature analogy for metals)

    Hello everyone, From what i know electrical resistance for metals is a constant, but in fact it varies with temperature but not voltage. Explanation for metals and temperature is something like "heat, which is in fact average speed of electrons, does obstruct tranmission of other electrons...
  21. G

    B The rubber sheet analogy in Relativity

    Can anyone here settle(or contribute to ) a question that is ongoing at another forum? Who came up with the idea of the rubber sheet analogy in Relativity? Some there have wondered if it was the "rubber sheet geometry" as topology was described as ,apparently that may have ,perhaps...
  22. B

    A Analogy of counterterms of gauge in GR

    In gauge theories, the counterterms in the equation to balance the gauge freedom (like the phase in electrodynamics) produce the forces of nature. In GR.. what is the equivalent of the counterterms and what is the equivalent of the phase or isospins freedom in electroweak)?
  23. B

    B Is General Relativity Merely a Classical Framework for Calculations?

    I want to ask this in the Relativity forum but thought there are more quantum experts here. So most of you Bhobba, Neumeier, etc believe the world is really classical and all the quantum things are just for calculation purposes or aids. Can you take the analogy to General Relativity? Can we say...
  24. M

    A Is this a valid physical analogy for the Riemann Hypothesis?

    http://arxiv.org/abs/1202.2115 I know Arxiv isn't a real journal, but this caught my eye. Is this a meaningful physical interpretation of the Riemann hypothesis? From what I understand, the zeta function can be modeled as a wave, but attempting to solve for the real part requires infinite...
  25. M

    Heat and mass transfer analogy to find average Nusselt no.

    I am trying to find an expression for the average Nusselt number corresponding to heat transfer from an isothermal disk. Given: ShD≡hm(r)D/DAB=Sho[1 + a (r/ro)n] (1) Sho=hm(r=0)D/DAB=0.814ReD1/2Sc0.36 (2) Relevant equations: Average nusselt number is defined as Nuav=havD/k where k...
  26. G

    I Is Maxwellian Gravitoelectromagnetism a useful analogy?

    I'm referring to the stuff in here: https://en.wikipedia.org/wiki/Gravitoelectromagnetism Is it a good analogy to conceptualize for beginners who have just started GR?
  27. Erebus_Oneiros

    I Angular Momentum, classical vector analogy?

    If one can't ever know all the three components of (QM) angular momentum, then can it even be considered as a "vector"? Is it only cause it transforms as a vector in a coordinate transformation?
  28. T

    B Brian Greenes' Tornado Analogy

    On his book of the elegant universe when he was explaining the warping of spacetime he use an analogy of a toy called tornado. Basically a spinning machine like a merry go round. Anyway he said, let's give one ruler to the slim who is at the wall of the tornado,to measure the circumference...
  29. alw34

    Does this dynamic model complement the Balloon Analogy?

    This is a kind of cooperative problem solving post. But don't be too terribly 'focused' because likely I have missed important issues. I had not seen a dynamic illustration like this before: maybe I am over impressed, weak-kneed, like seeing Kate Hudson the first time?? In Wikipedia at...
  30. Rob Haskell

    Questions about the balloon analogy

    I've been thinking about the balloon surface analogy and I want to ask some questions. Perhaps I am pushing it too far. But in that case it seems important to find its limits. My understanding is that the this analogy is used to illustrate the expansion of the universe and in particular how it...
  31. K

    Column analogy (Hardy Cross) - Carry Over Factor and stiffness

    Hi all, 1. Homework Statement Book example: Determine using the column analogy method, the carry over factor from A to B and the stiffness at A for a propped cantilever. (Propped end is defined as A, and fixed end is defined as B) 2. Relevant principles 1. Moment at any point M = M_{s} -...
  32. kostoglotov

    A reasonable analogy for understanding similar matrices?

    I don't really feel that I understand what it means for two matrices to be similar. Of course, I understand the need to understand ideas on their own terms, and that in math analogies are very much frowned upon. In asking if you know of any "reasonable" analogies for what it means for two...
  33. phinds

    Insights The Balloon Analogy .... the Good, the Bad, and the Ugly - Comments

    phinds submitted a new PF Insights post The Balloon Analogy ... the Good, the Bad, and the Ugly Continue reading the Original PF Insights Post.
  34. Rapier

    Quantum Theory of Earth Satellite Analogy to Bohr Model

    Problem: In analogy to the Bohr Theory of the hydrogen atom, develop a quantum theory of Earth satellites, obtaining expressions for the orbit radius (r) and the energy (E) in terms of the quantum number (n) and the other relevant parameters. A satellite of mass 1000 kg is in a circular orbit of...
  35. S

    What Happens When a Street Urchin Walks Into the Higgs Boson Analogy?

    i was thinking about the Higgs Boson analogy that was put forward to help describe how it works/interacts to produce mass, of a very famous person walking into a party, everyone gathers round impedes progress, high interaction with Higgs field and particles therefore high mass, and then a less...
  36. Logan Johnston

    How Is This Quantum Analogy Incorrect?

    Homework Statement "Sometimes the idea of the quantum is compared to the units we use for money. A dollar can be divided into smaller units, where the cent is the smallest possible unit. How is this analogy incorrect? Homework Equations E=nhf The Attempt at a Solution My thought is that...
  37. E

    Geometry as the Classical Limit: Examples and Analogies in Physics

    Can anyone give other examples where the geometry is the classical limit of another theory? I can give one. For example. The body curves of a woman is geometric.. so the geometry is the result of the bones and internal structure of the physical body. Likewise, in General Relativity, could the...
  38. G

    Higgs field and my non-physicist friend

    I have heard many physicists in the media attempt to describe the Higgs boson in terms of analogies. Many seem to my amateur physicist mind to fall down immediately. One such analogy is that particles with mass interact with the Higgs field as if swimming through treacle. This is particularly...
  39. DaveC426913

    "Speed limit of light" analogy

    Thought of this while driving home from the lofters. As if we need one more analogy for relativistic speed limits, but here goes... Q: How is c a speed limit? Why can't we just go a little faster and exceed it? A: Behold an analogy as to how geometry can limit movement, no matter how fast you...
  40. PWiz

    Explaining Energy in Cosmological Expansion: A Balloon Analogy

    Sorry to bother you all with another-of-its-kind (most probably unsatisfactory) analogy that I came up with myself (error detection sirens should be blaring now) to better understand "energy" in cosmological expansion, but I just can't rest until I find out how (in)accurate it is from you all. I...
  41. osotou

    Analogy for recession of galaxies > the speed of light

    For a lay person such as myself, it's very easy to get confused and stumble around a bit, trying to understand how galaxies can be receding greater than the speed of light when the speed of light is the cosmological speed limit. It's easy to make the mistake of saying 'Ha! There are whole...
  42. Abtinnn

    Rubber Sheet Analogy: How Mass Bends Spacetime

    I have a question on GR. To what extent is the rubber sheet analogy correct? To be more specific, in that analogy, an object with mass M bends the 2-D space (the sheet) into a third dimension (the sheet goes downward). Does this imply that in out universe, an object with mass bends the spacetime...
  43. A

    Trampoline analogy for gravity

    The trampoline analogy tries to explain gravity in terms of space time curvature the orbit of objects around a massive object can be understood, but what about centre of gravity of the massive object, the images of trampoline is generally shown as seen from top where the massive object is making...
  44. B

    Can Quantum Mechanics Explain the Expansion and Contraction of Space-Time?

    People often use the expanding balloon with galaxies on the surface to represent the expansion of space. But this view doesn't show how this expansion works in 3d and it doesn't show how gravity comes into play. Instead of putting the galaxies on the surface of the balloon all we have to do is...
  45. G

    Is blowing up a balloon a great analogy for Avogadro's Law?

    Hello, I was learning about Avogadro's Law and trying to find some real-life example of it. It mainly states that: For a given mass of an ideal gas, the volume and amount (moles) of the gas are directly proportional if the temperature and pressure are constant. So let's say I have a balloon...
  46. P

    A festive analogy for interpreting quantum mechanics

    While browsing this festive morning I came across Peter Woit's "(his Oct. 3rd 2011 'Not Even Wrong') statements that: "the fundamental problem of the interpretation of quantum mechanics (is): why don't we see superpositions " and that: "the confusing question is ...how classical behaviour...
  47. T

    Challenging Verbal Analogy Puzzle: Can You Solve It?

    There it is. I'll congratulate the solver upon discovering the solution. Hint: the answer is not a one-, two-, three-, or four-letter solution. Good luck.
  48. gfd43tg

    Mass balance for diffusion and analogy to heat conduction

    Hello, I just began learning mass transfer, and I am trying to use analogies from heat transfer to help me solve problems. For example, if you have one dimensional heat transfer through a plane wall, I would start with a general energy balance. $$\frac {dE}{dt} = \dot Q_{x} - \dot Q_{x + \Delta...
  49. A

    Raynolds Analogy: Use & Application for Convection HX Coefficient

    What is Raynolds Analogy and its use/application in convection heat transfer coefficient?
  50. liometopum

    Looking Again at the Balloon Analogy

    Has anyone here ever asked these questions about the balloon analogy? 1. If the universe actually was the 3D surface volume of an expanding 4D hypersphere, how big would the radius be? (let the radius of the observable universe be 46.25 billion light years) 2. How fast is it expanding...