Talk:Reflection (physics)

message: Is this right: "Depending on the nature of the interface, i.e., dielectric-conductor or dielectric-dielectric, the phase of the reflected wave may or may not be inverted."?  I thought the phase inversion of reflected light depended on the relative refractive index of the interfacing materials.  Maybe both are right, but probably the article should be more clear.  --Chinasaur 05:42, 4 Aug 2004 (UTC)
replies: text: It is correct, but poorly written. We actually have an article on this topic.--Srleffler (talk) 15:32, 13 July 2019 (UTC)
thread_title: Phase inversion

message: A quantum mechanical description of reflection would be nice if someone had the ability to explain it, since this article doesn't reveal the reason for which light is actually reflected from a surface.
: Seconded!  There must be a reasonable/logical explanation for reflection in terms of QM.  As it is, the article just refers us to a Feynman book. For an article of high importance on a very common subject, someone with the knowledge needs to get this part up to scratch.  I seem to remember Feynman saying something about it in these lectures... [url]http://vega.org.uk/video/subseries/8[/url] but I can't remember if he address QM reflection specifically. David 218.143.30.1 (talk) 05:15, 30 July 2009 (UTC)
thread_title:  QM reflection 

message: "all non-shiny objects that are not black."
It's accurate; I just thought it sounded... amusing, probably because of the use of the word "shiny."  Not going to edit to "all objects that do not shine and are not black" because that's a tad verbose and there's no real point.  Just throwing that out there.  --165.134.132.122 22:26, 18 August 2005 (UTC)
thread_title:  Easily Amused 

message: I have some photographs on my userpage of the famous curved, reflective sculpture Cloud Gate that could be illustrative. Spikebrennan 17:30, 6 July 2006 (UTC)
thread_title:  Images 

message: I was thinking a little history could be added to this article such as the Euclid's contributions to the field (is his the earliest known studies? Who are the other people noted for their theories on reflection?) and maybe links to and expansion of the term Catoptrics. 69.72.93.142 14:11, 2 December 2006 (UTC)
thread_title: A little history?

message: If "part of the light is reflected and the remainder is refracted", then I guess a black surface does not absorb light. Does it turn all the light into non-visible electromagnetic radiation? (I doubt it). We all know that a black material heats up more quickly than a white material when exposed to solar lignt. Where does that thermal energy come from? Just from absorbed infrared or ultravioolet radiation? ... 
The paragraph about the quantic interpretation says that photons are sometimes absorbed. Do you mean that there are some cases in which the light does not produce heat when it strikes an opaque object, or passes through a transparent medium such as the air or water? Cases in which the light is completely "cold"? 
In my opinion, these are questions that one should be able to answer after reading this article, but the article is not clear enough with respect to this topic. I am not an expert in optics, I just wanted to give to the experts an advice for improving the article. Regards, Paolo.dL (talk) 22:26, 6 January 2008 (UTC)
thread_title:  What about absorption? 

message: I am trying to understand what happens when a surface gets smoother and smoother e.g., when it is polished, but the same idea applies to sound waves, I am sure. What happens to a surface's reflections as it gets smoother? A metal surface with a small-enough pattern of saw-toothed ridges will reflect sound crisply; if you make the pattern small enough, I think you will even get nice sharp specular reflection of light. But how small do they have to be to appear smooth acoustically? Optically? I assume it will be a function of wavelength... —Ben FrantzDale (talk) 00:05, 27 May 2008 (UTC)
thread_title:  Diffuse->specular 

message: Reflection is described in detail in the article, via laws of reflection, Maxwell's equations, etc., but what I don't see is the reason that reflection occurs.
Maybe I just missed it.  But otherwise, I think this article would be distinctly enhanced by an explanation of why reflection occurs.  In other words, a ray of light strikes a certain medium.  There is something special about that medium -- in part its extreme smoothess, of course -- that causes the light to follow the laws of reflection.  Can someone enlighten us about why this happens?  This should include an explanation of why some materials make better mirrors than others.
Note:  One is tempted to say it's just like a ball bouncing off a hard surface.  But for one thing, a photon is much smaller than an atom, and from the point of view of the photon I would guess that what appears to us as a very smooth surface would be quite irregular -- after all, the photon could strike an atom at a relatively small or large distance from its nucleus.Daqu (talk) 07:42, 4 September 2008 (UTC)
replies: text: Although Compton scattering of photons can occur, classical reflection and refraction of electromagnetic radiation are explained by examining its behaviour as a wave, so there's no analogy with a ball. Electromagnetic radiation has both an alternating electric and an alternating magnetic field. These fields interact with the electrons in the medium they are passing through or into. The effect of this interaction on a macroscopic scale can be deduced from Maxwell's equations and - in the particular case of moving into a different medium - the Fresnel equations as noted in the article. As you can see, the "why" has not got much to do with smoothness, it's a result of the way a wave behaves in a transmittive medium. Obviously a non-smooth boundary between media allows multiple angles of reflection and refraction, allowing dispersion of the wave in all directions, which is why you don't get a clear reflection from a rough surface. --RexxS (talk) 04:32, 8 October 2008 (UTC)

text: See Correspondence principle. Maxwell's equations are just fine.--Srleffler (talk) 23:21, 20 August 2012 (UTC)

text: Complementarity (physics) is also relevant—there is little point in trying to gain an intuitive understanding of a wave-like property of light using a particle-like model.--Srleffler (talk) 23:33, 20 August 2012 (UTC)
thread_title: But '''why?'''

message: Removed from the article:
I have removed this text and the associated image because:
*the analysis of the image is original research, which is not permitted.
*the text is not supported by a citation to a reliable source as required by Wikipedia:Verifiability.
*the content is off-topic for this article. There are reflections, and there are mirages. It's not surprising that one can have a mirage of a reflection, but this isn't really a distinct effect, and doesn't really merit a section in the reflection article. Even if it were on-topic, it certainly wouldn't merit placement above the sections on "other types of reflection". 
*the image, while interesting, is not technically well-suited to Wikipedia. The features of interest are hard to discern, and the green and red rims described in the text are only visible if the full resolution image is loaded and zoomed in (~4× on my monitor).--Srleffler (talk) 04:58, 20 November 2008 (UTC)
replies: text: May I please ask what features of interest are hard to discern? The mirage, sun glitter? Even green upper edge is seen in thumbnail.User:Srleffler made it sound like it is very common to see a mirage of reflection The user writes:"It's not surprising that one can have a mirage of a reflection". In reality the mirage like this one is extrimly rare and is very much surprising, and IMO people, who lost the ablility to get surprised would never discover anything new. I am also not sure what original research the user is talking about. I took an image of a phenomenon that I saw with my own eyes. What is really in question in this image, sun glitter, mirage, green rim? I believe both sun glitter, mirage, green rim/flash were recearched long time ago and proven to be exist.IMO the image is good enoug and interesting enough, and on-topic enough to be in the article. We could leave alone (do not talk about green and red edges, if it is confusing), but I believe it is a great image to talk about reflection versus refraction.After all this image depicts one of a very few situations, which show both reflection and refraction together.--Mbz1 (talk) 15:55, 22 November 2008 (UTC)
replies: text: The fata morgana is, to the untrained eye, just an indistinct blur across the top of the photo. The colored edges are also not obvious. To understand what one sees in the image, one needs a more detailed understanding of atmospheric refraction than we should expect of readers of this article, nor should this article explain those phenomena in enough detail to make the image interpretable, because that explanation is off-topic. It would be fine for the article on fata morgana, but is not appropriate here. Basically, the image doesn't "say" much about reflection, but it does say something significant about fata morgana mirages.--Srleffler (talk) 17:25, 22 November 2008 (UTC)
thread_title:  Miraged reflection 

message: The article makes clear that a reflective surface may be solid "mirror" or liquid "water".
I'm curious, though, as to whether it is possible to create a reflective surface with an inert gas, such as argon.  And if so, how would one go about doing such? Pine (talk) 19:32, 13 February 2009 (UTC)
replies: text: Gasses can reflect, if there is a transition in index of refraction. It's hard to get a large, sharp change in index with gasses, though. This isn't the right place to ask this kind of question. Article talk pages are for discussion related to improving the article. You want the Science reference desk.--Srleffler (talk) 01:09, 14 February 2009 (UTC)
thread_title:  Creating a vapor reflective surface [?] 

message: I am wondering if the third law of reflection, light paths are reversible, should be added to the article? It is sort of important to reflection that people know of that and I do believe that it is a law of reflection. Mcfar54 (talk) 09:31, 25 March 2009 (UTC)
replies: text: Can you cite a source that refers to this as a "law of reflection"?--Srleffler (talk) 04:18, 15 May 2009 (UTC)
thread_title: Third Law of Reflection?

message: If the mirror or reflective surface is moving at very high speed, in the direction of its own plane, then do the angles of incidence and reflection still equal each other?  Is the frequency of the reflected light the same as that of the incident light?  Has this senario been tested either experimentally or via the equations?  Norman Sheldon (talk) 14:52, 7 January 2011 (UTC)
replies: text: I guess that if we describe this from the point of view of the reflective surface reference frame, we will see a (Doppler-shifted) light coming from a moving source, that will be reflected by the non-moving surface in the usual way, with equal incidence and reflection angles and with no shift in frequency. --GianniG46 (talk) 21:56, 7 January 2011 (UTC)

text: This isn't really the right place for this. Article talk pages are for discussions related to improving the article, not for general questions. The right place to ask a question like this is at the Science Reference Desk. If you post your question there, I'm sure you will get some enthusiastic discussion of it. It's an interesting question.--Srleffler (talk) 20:12, 9 January 2011 (UTC)
replies: text: I fully agree with Srleffler, and, moreover, your questions concern relativity, rather than optics. Anyway, just to avoid leaving matters pending, I suppose that the Lorentz transformations would affect in the same way the incident and reflection angles, which make the same angle (in absolute value) with relative velocity, so the two angles will stay equal, while the reflective properties of the surface will be "Doppler-shifted", if they depend on wavelenght. --GianniG46 (talk) 08:45, 10 January 2011 (UTC)
thread_title:  Does the speed of the reflecting surface make any difference? 

message: Is there anything at Abnormal reflection that's worth merging to this article?  That article has no content and looking at its references suggests that it's not a unique physical phenomenon but rather is a pair of words describing any observations of anomolous reflection effects. --Wtshymanski (talk) 22:02, 30 October 2011 (UTC)
replies: text: A short section here discussing abnormal reflection might be a better solution than a separate article covering a variety of disparate phenomena.--Srleffler (talk) 00:04, 31 October 2011 (UTC)
replies: text:  OK, but I'm at a loss to find something to merge; I suppose one could summarize the "abnormal reflections" in the several items referenced, but there doesn't seem to be any unity of those publications as they are describing different effects. --Wtshymanski (talk) 03:13, 31 October 2011 (UTC)
thread_title: Suggested merge

message: In the section about total internal reflection, shouldn't the example of X-ray actually be "Total external reflection"? --Cyferz (talk)  —Preceding undated comment added 19:39, 16 February 2012 (UTC)
thread_title: Total Internal Reflection

message: This physics article presents itself as a general discussion of the physical phenomenon of reflection.  The two opening paragraphs give examples of reflection that include sound waves, water waves, electromagnetic waves, and seismic waves.  But what follows is a discussion almost exclusively limited to the reflection of visible light, and which includes no examination of the broader principle of reflection as a consequence of the behavior of waves as they encounter constraints on their motion.
The article states, "Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated."  This statement can be true, but a change of media is not necessary for reflection unless air at different temperatures or water of varying depth is considered different media.  Nowhere in the article is it pointed out that the characteristic that results in reflection and refraction is the change (or rate of change) in propagation speed (or phase velocity) of the wave in the medium.
The "Mechanism" section goes into a level of detail that could mislead the reader into thinking that Maxwell's equations are fundamental to an understanding of wave reflection.  It's a bit like using a description of gravity and the properties of water to explain reflection in ocean waves.  The truly remarkable thing, and something this article manages to miss, is that the reflection of light as it encounters changes in refractive index, and the reflection of ocean waves that encounter changes in depth are really two manifestations of the same thing.  Maxwell's equations do not explain reflection in any meaningful way.  Rather, they explain why electromagnetic waves obey the same laws as other kinds of waves.  --Alt Livingston (talk) 21:55, 3 June 2012 (UTC)
replies: text: These are very good points. If you are so inclined, feel free to try changing the article to present the topic in a more general way.--Srleffler (talk) 02:02, 4 June 2012 (UTC)
thread_title: General Comments

message: Bragg Reflection is either a different type/mechanism of reflection or an interesting special case of one - or just a different level of abstraction.
I've been studying it to understand play-of-color in precious opal - including contra-luz opal -- but the Braggs's discovery was for/with X-Rays.
It seems like this article could benefit a lot by including info on that somewhere.
PMH232 (talk) 18:12, 29 May 2015 (UTC)
thread_title: Bragg Reflection

message: This is among the worst technical articles I've had the misfortune to find on Wikipedia. Apparently, at some point it included some actual MODERN physics, but if so, it has been removed. (I came to this article expecting to find, at least, a reference to the quantum mechanics behind the 17th Century geometric optical "science". Nothing.) The first sentence insists that reflection must be defined in the optical media in which the "wavefront" travels. Really? OPTICAL media?? Wrong. In the 2nd paragraph, we learn "many" types of EMR reflect. Really? Not "all" but "many"? Rubbish. In the next paragraph we read:"In specular reflection the phase of the reflected waves depends on the choice of the origin of coordinates, but the relative phase between s and p (TE and TM) polarizations is fixed by the properties of the media and of the interface between them." Of course, no explanation, not even a definition, of s, p, TE, and TM is provided. GARBAGE. (Of course, if a reader has to spend 20 minutes somewhere else learning what a "phase" is, nevermind a "wavefront". The next paragraph informs us that a mirror is a model for specular light reflection. A model, not an example, but a model. Brilliant. I could go on, and on, and on, but if anybody thinks this article is useful, perhaps they could spend some time cleaning it up, personally, I think it is so bad that it is beyond redemption.40.142.182.216 (talk) 16:20, 20 March 2017 (UTC)
replies: text: Thank you for your suggestion. When you believe an article needs improvement, please feel free to make those changes.  Wikipedia is a wiki, so anyone can edit almost any article by simply following the edit this page link at the top. The Wikipedia community encourages you to be bold in updating pages. Don't worry too much about making honest mistakes—they're likely to be found and corrected quickly. If you're not sure how editing works, check out how to edit a page, or use the sandbox to try out your editing skills.  New contributors are always welcome. You don't even need to log in (although there are many reasons you might want to). --Srleffler (talk) 01:28, 21 March 2017 (UTC)
thread_title:  Status March 2017 

message: Bc  — Preceding unsigned comment added by 197.231.239.109 (talk) 08:37, 14 August 2022 (UTC)
thread_title:  The formation of image 

message: The redirect Reflection (physics has been listed at redirects for discussion to determine whether its use and function meets the redirect guidelines. Readers of this page are welcome to comment on this redirect at  until a consensus is reached.  Utopes (talk / cont) 18:28, 3 March 2024 (UTC)
thread_title:  "[[:Reflection (physics]]" listed at [[Wikipedia:Redirects for discussion|Redirects for discussion]]