# How can light be both a wave and a particle? **URL:** \ **Category:** Cecil's Columns/Staff Reports\ **Created:** [April 3, 2003, 2:37pm UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199 "2003-04-03T14:37:49Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![crywalt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crywalt/32/3224_2.png) [@crywalt](https://boards.straightdope.com/u/crywalt)\ **Post date:** [April 3, 2003, 2:37pm UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199/1 "2003-04-03T14:37:49Z")
Commenting on Chronos’ excellent explanation of wave/particle duality at [http://www.straightdope.com/mailbag/mlightwaveparticle.html](http://www.straightdope.com/mailbag/mlightwaveparticle.html) I can bring in good old Robert Heinlein to answer the question more fully. This is not a quote, but a paraphrase: Modern physics is inseparable from mathematics. You can’t talk about physics in English and have it make any sense at all, you have to speak the language of physics, and that’s math. So there you go. The wave/particle duality doesn’t make any sense in English, but the math works out. ---
**Author:** ![Moe](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/moe/32/2972_2.png) [@Moe](https://boards.straightdope.com/u/Moe)\ **Post date:** [April 3, 2003, 6:03pm UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199/2 "2003-04-03T18:03:58Z")
I still don’t get it 😕 Surely the mathematical explanations and language has to translate into something tangible eventually, no?? Afterall, we are talking about physical phenomena here (i.e. stuff that _really_ happens). ---
**Author:** ![crywalt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crywalt/32/3224_2.png) [@crywalt](https://boards.straightdope.com/u/crywalt)\ **Post date:** [April 3, 2003, 6:19pm UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199/3 "2003-04-03T18:19:17Z")
I think the point is, no, we’re not talking about stuff that \really\ happens, we’re talking about a \model\ of stuff that really happens. A mathematical model. It’s very important to keep in mind that light isn’t \really\ a wave OR a particle or really anything but itself. So the model, being mathematical, doesn’t make any sense at all when translated to a less detailed model involving the English words `wave'' and `particle.’’ ---
**Author:** ![user\_hostile](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/user_hostile/32/474_2.png) [@user\_hostile](https://boards.straightdope.com/u/user_hostile)\ **Post date:** [April 3, 2003, 6:21pm UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199/4 "2003-04-03T18:21:37Z")
**Arnold** , the following is more a question than a comment, so this posting may be more applicable to **General Questions** , but I’m hoping that this comment will at least provoke a different approach to the wave/particle duality paradox. First the background: In my college days, I was taking the first of a series of E & M classes in my major (EL – _Electronic_ Engineering _not_ Electrical). I remembered asking the teacher what the “Electric Field” was. He kept telling me that it was manifestation of the E field emanating from the charge. He was rather arrogant with me thinking that how could somebody not grasp this basic concept? Most everyone in the class assumed I was not one of the brighter students (and I wasn’t, by the fact my question was probably phrased pretty poorly, but it still seemed important to me that it be answered). I kept asking the question, and the professor became angry–Finally, someone grasp the essence of what I was saying. That peer of my said, “He’s not asking about what exist between two charges, he’s asking what the stuff between the charges is made of.” The teacher’s expression changed from one of anger to one of total befuddlement and said, “I don’t know!”. I was feeling pretty intimidated by then, so I just dropped the question. I finally found the answer in a physics book 10 years later written by Larry Gonick & Art Huffman **The Cartoon Guide to Physics**. In it, he describes the E field as a manifestation of “virtual” photons, which surround each charge. Each charge has a swarm of these invisible particles coming and going. The closer the virtual photon to the charge, the more energy it has; conversely the further away the less energy it has. The virtual photons are only indirectly detected. To enable them to appear, one needs to move the charge such that the virtual photon can’t return to home. Classic example: Medical X-rays. Slam an electron with 10 to 20 electron kV of into a Tungsten target, and the charges in the inner electron orbits (of W) get rattled. The virtual photons which stayed close to home (i.e., the high energy ones) have no place to go, and shoot on out to be absorbed by the air, tissue, or x-ray film. If it’s a microwave, start twisting a bunch of charges. If it’s a radio wave, start oscillating the charge. In each case, virtual photons of different energies find they’ve been “evicted.” It’s ironic that Larry & Art’s ‘toon book, which is equivalent to a 1st year college introduction to physics would provide me an answer. None of my actual college physics books (general, modern, solid-state, E & M) ever mentioned this. (Did anyone out there in Dope land learn this in college?) This of course brings up a duality the magnetic field. What then is the magnetic field? Is there an analogy to the virtual photon? Or a different state of the virtual photon? Does a moving virtual photon field manifest as a magnetic field? Or is there some other character? Now to the meat of the argument: I too, having studied that non-intuitive wave particle duality (not only with photons, but any particle in general–electrons, neutrons, protons). And while I’ve grasped it on the periphery, I’ve never been satisfied in the “gut” with it. That’s why I’ve often wondered if one were to describe the wave-particle duality in a “virtual photon” way, if that would provide a simpler, more graceful explanation of this paradox. Has anyone looked at this approach? Or is my approach going to win an **Ignoble** Prize in Physics along the lines of squaring the circle with a compass and a ruler? ---
**Author:** ![John\_W.Kennedy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_w.kennedy/32/1031_2.png) [@John\_W.Kennedy](https://boards.straightdope.com/u/John_W.Kennedy)\ **Post date:** [April 3, 2003, 6:24pm UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199/5 "2003-04-03T18:24:18Z")
Yes, it does. But the plain fact is that the subatomic world isn’t like the world as we know it. Light isn’t a wave _or_ a particle. It is something that behaves according to a certain set of equations, and that is totally unlike anything we have, or can have, practical experience of. Sometimes that behavior resembles the behavior of a wave; sometimes it resembles the behavior of a particle. But it isn’t either. We’re in the position of a child who, being told that sex feels something like a sneeze, wonders what all the fuss is about. ---
**Author:** ![BioHazard](https://avatars.discourse-cdn.com/v4/letter/b/3bc359/32.png) [@BioHazard](https://boards.straightdope.com/u/BioHazard)\ **Post date:** [April 3, 2003, 6:37pm UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199/6 "2003-04-03T18:37:40Z")
I read in a book somewhere that light (electormagnetic radiation) could be a bend in a higher dimension we have no way of seeing, similar to how gravity could be a bend in Space-Time. The book was an older one about String Theory. Don’t know if that helps anyone. ---
**Author:** ![crywalt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crywalt/32/3224_2.png) [@crywalt](https://boards.straightdope.com/u/crywalt)\ **Post date:** [April 3, 2003, 6:39pm UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199/7 "2003-04-03T18:39:08Z")
\> We’re in the position of a child who, being told that sex feels \> something like a sneeze, wonders what all the fuss is about. Well if that isn’t the best metaphor I’ve ever heard, I don’t know what is. ---
**Author:** ![Pedro](https://avatars.discourse-cdn.com/v4/letter/p/919ad9/32.png) [@Pedro](https://boards.straightdope.com/u/Pedro)\ **Post date:** [April 3, 2003, 7:29pm UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199/8 "2003-04-03T19:29:05Z")
> [@](#): > > In it, he describes the E field as a manifestation of “virtual” photons, which surround each charge. I really don’t like that image - and it’s all it amounts too, although virtual particles are becoming increasingly popular in modern physics, I believe. ---
**Author:** ![xenothrope](https://avatars.discourse-cdn.com/v4/letter/x/7ab992/32.png) [@xenothrope](https://boards.straightdope.com/u/xenothrope)\ **Post date:** [April 4, 2003, 2:13am UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199/9 "2003-04-04T02:13:48Z")
I really dont know a whole lot about light and how it works. However from my meager understanding, light is its own thing. We cant define it with other things, its like a primary color. In short light doesnt follow the rules, It MAKES the rules. Perhaps I am WAYYY off but the whole packet vs. wave debate really is silly imho due to the fact that it is neither and both. In other words its like a packet-carrying wave or something. Anyway I think I shall just leave that as my $0.02 and shut up. -x out ---
**Author:** ![The\_Ryan](https://avatars.discourse-cdn.com/v4/letter/t/7feea3/32.png) [@The\_Ryan](https://boards.straightdope.com/u/The_Ryan)\ **Post date:** [April 4, 2003, 7:06am UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199/10 "2003-04-04T07:06:28Z")
> [@](#): > > \*Originally posted by Moe \* > \*\*I still don’t get it 😕 > > Surely the mathematical explanations and language has to translate into something tangible eventually, no??\*\* Why? Can you explain how a microwave works in Latin? The English language simply wasn’t designed to explain light. As for the column, mostly good, but the response to Ed was a bit off. > [@](#): > > As for the directions of these fields, for a uniform beam of light traveling in some direction (usually referred to as a plane wave), the electric field will always be in one plane, and the magnetic field will always be in a different plane at right angles to the electric field plane. Both the electric and magnetic fields are perpendicular to the direction the wave is moving. Both the magnetic and electric fields extend throught all of space; they are not confined to a single plane (and even if they were, how could two planes both be perpendicular to the same line?). Perhaps Chronos is remembering that schematic of the wave that shows two waves at right angles to each other. It’s just that; a schematic. Each wave which is shown is a cross section of the entire wave. To see why this must be, put your thumb and forefinger in the shape of an L. Your thumb is the electric field, your forefinger the magnetic. If something happens to the base of your thumb, that can affect the base of your forefinger. But if something happens to the end of your thumb, how will that affect the end of your forefinger? Where this “right angles” stuff comes in is that in a plane wave, all the electric field lines are all parallel to each other, and the magetic field lines are parallel to each other. Moreover, every electric field line is perpendicular to every magnetic field line, and both of them are perpendicular to the direction of propogation. ---
**Author:** ![Desmostylus](https://avatars.discourse-cdn.com/v4/letter/d/c57346/32.png) [@Desmostylus](https://boards.straightdope.com/u/Desmostylus)\ **Post date:** [April 4, 2003, 7:48am UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199/11 "2003-04-04T07:48:02Z")
**user\_hostile** , the stuff you are looking for is Quantum Electrodynamics (QED). And, yes, it does get taught in college. ---
**Author:** ![monado](https://avatars.discourse-cdn.com/v4/letter/m/ee59a6/32.png) [@monado](https://boards.straightdope.com/u/monado)\ **Post date:** [April 4, 2003, 4:31pm UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199/12 "2003-04-04T16:31:05Z")
Light’s wave nature is demonstrated by interference patterns when light shines through two pinholes. Light’s particle nature means that a “pinhole” can be chosen that lets through one photon at a time. But a series over time of these single photons creates an interference pattern! The wave/particle duality of light simply doesn’t behave as we’d expect by “common sense” inspection of the macroscopic world. We have to resort to mathematics to bolster our necessarily imperfect understanding. I agree: Heinlein said it best. The language of physics is math. ---
**Author:** ![dsdtzero](https://avatars.discourse-cdn.com/v4/letter/d/45deac/32.png) [@dsdtzero](https://boards.straightdope.com/u/dsdtzero)\ **Post date:** [April 4, 2003, 5:08pm UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199/13 "2003-04-04T17:08:22Z")
user\_hostile, There is also a good elementary treatment of QED by one of the creators of the theory… QED The Strange Theory of Light and Matter by Richard Feynman ---
**Author:** ![crywalt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crywalt/32/3224_2.png) [@crywalt](https://boards.straightdope.com/u/crywalt)\ **Post date:** [April 4, 2003, 5:14pm UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199/14 "2003-04-04T17:14:42Z")
I have honestly tried to get through Feynman’s QED – and this after going to engineering school and taking a year of physics, two years of calculus, linear algebra, and so on. And I really still didn’t get it. I blame myself to some extent. I once found a great Website explaining the math you’d need to know to understand string theory. For the first few subjects I was like, okay, I learned that, yeah, I remember that; all right, I took that, um, well, I’ve heard of that… It rapidly progressed into WTF territory. Here’s a similar page: [http://superstringtheory.com/math/math1.html](http://superstringtheory.com/math/math1.html) ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 4, 2003, 5:41pm UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199/15 "2003-04-04T17:41:32Z")
Quoth **The Ryan** : > [@](#): > > Where this “right angles” stuff comes in is that in a plane wave, all the electric field lines are all parallel to each other, and the magetic field lines are parallel to each other. Moreover, every electric field line is perpendicular to every magnetic field line, and both of them are perpendicular to the direction of propogation. How is this different that what I said? ---
**Author:** ![user\_hostile](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/user_hostile/32/474_2.png) [@user\_hostile](https://boards.straightdope.com/u/user_hostile)\ **Post date:** [April 4, 2003, 5:56pm UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199/16 "2003-04-04T17:56:00Z")
**dsdtzero** I read Feynmans QED book. I don’t recall a discussion of “virtual” photons; but that was five years ago. Good book, though. **Desmostylus** Whew! Well, I glad to here that–but, does QED deal with my paper tiger breakthrough in duality? **The Ryan** What about elliptical polarization? Isn’t that a case of less then a right angle with respect to E & M planes. Someone needs to talk about the _Poynting_ [spelling?] vector as a descriptive example of an E&M plane wave structure ---
**Author:** ![Pedro](https://avatars.discourse-cdn.com/v4/letter/p/919ad9/32.png) [@Pedro](https://boards.straightdope.com/u/Pedro)\ **Post date:** [April 4, 2003, 6:03pm UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199/17 "2003-04-04T18:03:12Z")
> [@](#): > > I have honestly tried to get through Feynman’s QED – and this after going to engineering school and taking a year of physics, two years of calculus, linear algebra, and so on. And I really still didn’t get it. I blame myself to some extent. That was his only book I didn’t enjoy. Maybe because I have a translated version. But what is there not to get? He doesn’t use any math at all, calls vectors “arrows” and feels the need so explain such complicated technical terms as “probability”. You just have to believe that what he says is true. ---
**Author:** ![Pedro](https://avatars.discourse-cdn.com/v4/letter/p/919ad9/32.png) [@Pedro](https://boards.straightdope.com/u/Pedro)\ **Post date:** [April 4, 2003, 6:05pm UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199/18 "2003-04-04T18:05:25Z")
…and feels the need to explain such complicated technical terms such as “probability”. Sorry. ---
**Author:** ![crywalt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crywalt/32/3224_2.png) [@crywalt](https://boards.straightdope.com/u/crywalt)\ **Post date:** [April 4, 2003, 6:16pm UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199/19 "2003-04-04T18:16:31Z")
> [@](#): > > \*Originally posted by Pedro \* > \*\*…and feels the need to explain such complicated technical terms such as “probability”. Sorry. \*\* I think it was better the first way, actually. No, what I’m saying is that Feynman’s explanations on How the World Works made no more sense than the explanations for particle/wave duality have. Take the good old slit experiment: Fire two electrons through two slits, get interference pattern. Fire on electron through two slits, get interference pattern. One electron interferes with itself? It doesn’t make any sense at all – in English. But the math, I am told, checks out. For a layman like myself, QED is like the Catholic Holy Trinity: It doesn’t make sense, you just take it on faith. I don’t, of course, but that’s another argument. ---
**Author:** ![Pedro](https://avatars.discourse-cdn.com/v4/letter/p/919ad9/32.png) [@Pedro](https://boards.straightdope.com/u/Pedro)\ **Post date:** [April 4, 2003, 10:23pm UTC](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199/20 "2003-04-04T22:23:25Z")
Hehe the second “such” was not supposed to be there but a third post was too much. I know, I understand what you mean but Feynman does not offer an explanation, no one has one. Math has a beauty of its own and maybe that would count for a lot, seeing the math check out. [Next page](https://boards.straightdope.com/t/how-can-light-be-both-a-wave-and-a-particle/166199.md?page=2)