# The Nature of Light - Particle, Wave - both? **URL:** \ **Category:** Factual Questions\ **Created:** [January 2, 2003, 4:15pm UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216 "2003-01-02T16:15:28Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![scotth](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@scotth](https://boards.straightdope.com/u/scotth)\ **Post date:** [January 3, 2003, 5:27am UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216/21 "2003-01-03T05:27:42Z")
Maybe so, Ring. But, I have been right over Ph.D’s in their own field a number of times. That doesn’t necessarily mean that I am correct this time, but I am fairly certain that I am. It doesn’t mean he is correct simply because he has an Ph.D… If he is correct and has a Ph.D. in physics as you say, he will certainly be capable of demonstrating to me that he is indeed correct. Besides, there are many physicists that are not particularly strong in QED or QCD as they aren’t terribly relevant to what they are working on. I have been studying Feynman’s work for quite a while (about 7 years). I have read and followed all his popular stuff. I am working on the full treatment of QED now. When I say that I am working on it, I actually mean that I am finding out what I need to know in more detail to be able to get through it. The math is positively ass kicking. At the moment I am working my way through Max Born and Emil Wolf’s “Principals of Optics” to get a more solid grounding in the classical treatment of light. But, one thing that seemed quite appearent to me in most if not all the QED texts was the message to forget the dual nature of light. It is a nice stop on the way to understanding light, but looking at light strictly as particles is the way to really understand what is going on. One of the main purposes of the “sum over” business is to provide a means for explaining patterns that are consistent with inteference in a particle setting (single photons passing through the apperatus at a time) when wave like interference plainly could not be occuring. (see double slit experiment above) I’m no dummy either, and have enough background to likely follow any explanation that would demonstrate how/where my previous understanding is/was flawed. Hopefully Bonzer will return and correct me if I got it wrong, I always learn more when I lose an arguement than when I win one. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [January 3, 2003, 10:10am UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216/22 "2003-01-03T10:10:46Z")
Isn’t it simply that case, **scotth** , that you’re just saying the same thing in a different way; if **all** particles exhibit wavelike behaviour (interference, diffraction etc), then there’s nothing particularly special about photons (by which I’m supposing we mean a broader sense than just the visible spectrum). The way I heard it explained was (something like) that a single photon doesn’t actually pass through one or the other of the slits, it passes through the entire apparatus as (something like) a ‘probability wavefront’ (forgive me if I’m mangling terms here), thus each photon (or whatever it really is when it is in transit) displays the behaviour that we might expect at greater volumes. ---
**Author:** ![MC\_Master\_of\_Ceremonies](https://avatars.discourse-cdn.com/v4/letter/m/bb73d2/32.png) [@MC\_Master\_of\_Ceremonies](https://boards.straightdope.com/u/MC_Master_of_Ceremonies)\ **Post date:** [January 3, 2003, 10:24am UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216/23 "2003-01-03T10:24:16Z")
Interestingly you should be able to observe wave behaviour (e.g. diffraction) in tennis balls. Wave particle duality is governed by De Broglie’s equation, λ = h/mv ---
**Author:** ![Achernar](https://avatars.discourse-cdn.com/v4/letter/a/e274bd/32.png) [@Achernar](https://boards.straightdope.com/u/Achernar)\ **Post date:** [January 3, 2003, 10:45am UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216/24 "2003-01-03T10:45:28Z")
**MC** , I can’t quite read your formula, so I’m not sure what you put, but it may need a minor correction. For non-relativistic objects, the de Broglie wavelength is given by lambda = h / mv but more generally, it’s lambda = h / p ---
**Author:** ![WordMan](https://avatars.discourse-cdn.com/v4/letter/w/e8c25b/32.png) [@WordMan](https://boards.straightdope.com/u/WordMan)\ **Post date:** [January 3, 2003, 1:42pm UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216/25 "2003-01-03T13:42:17Z")
Well, I wasn’t quite expecting a debate, but I find the fruits of the discussion interesting, so no real complaints as long as you play nice. **Artemis** I appreciate your analogy - makes sense. **scotth** and **Bonzer** , your debate directly applies to my query (which would make sense, give the question heading up this thread). My intent with the post was more to work from the assumption that light exhibited both particle and wave behaviors (thanks to posters who steered me towards this language). Within that assumption, I wanted to see if I understand - in its simplest form - how light propagates without ether (I stated it was through its constant transitioning between energy states) and how its wave/particle duality played into that propagation - I didn’t state this in the OP, but I am curious as to whether any one discrete energy state could be thought of as a light particle - so if a photon is moving in a wave-like pattern, each point on the wave where it assumes a discrete energy state would “qualify” as a particle… Well, that was my going in thinking - the debate both supercedes it and clarifies (I think). If light is, as **scotth** asserts, particles, then my OP - or the intent behind it - is moot; if wave/particle duality holds sway, then it would be less correct to state that the each energy state qualifies as a particle and more correct to simply state that light can paradoxically exhibit particle and wave behaviors as it propagates - right? Carry on and thanks for the help. PS: **Scott Dickerson** , I couldn’t agree more about the unwieldy nature of words with regard to this and many other topics…but they are all we have on the ol’ SDMB, so I perservere. ---
**Author:** ![rampisad](https://avatars.discourse-cdn.com/v4/letter/r/858c86/32.png) [@rampisad](https://boards.straightdope.com/u/rampisad)\ **Post date:** [January 3, 2003, 1:54pm UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216/26 "2003-01-03T13:54:42Z")
> [@](#): > > by artemis > …under some observational conditions it may show the appearance of a particle, and under others it may show the appearance of a wave… I’m not going to get into arguments with PhDs here, but my understanding is that you’ll get the answer you expect. If you’re testing for particle-like aspects, you’ll get results that conform to a particle. If you’re testing for wave-like aspects, you’ll see waves. The _nature_ of the test is part of the universe being tested. The duality is so fundamental that it is meaningless to talk about one or other term as if they have independant meaning. As John Griffin explained (in In Search of Schrodinger’s Cat), you’ll be better off talking about slithy toves. So, my answer to the thread is … **yes** [hijack] is g8rguy a deliberately chosen name, or a mistype - should have been gr8guy (much more meaningful)??? [/hijack] ---
**Author:** ![artemis](https://avatars.discourse-cdn.com/v4/letter/a/91b2a8/32.png) [@artemis](https://boards.straightdope.com/u/artemis)\ **Post date:** [January 3, 2003, 3:16pm UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216/27 "2003-01-03T15:16:55Z")
> [@](#): > > \*Originally posted by scotth \* > \*\*Light is a particle. \*\* No, it is not. And it’s not a wave, either. The terms “particle” and “wave” have **no meaning** on the quantum level; that is, in fact, one of the most counter-intuitive aspects of quantum mechanics. To attempt to view quantum phenomena using the semiotic tools we’ve devised to describe the macroscopic world is an excercise in futility. Our everyday language doesn’t have terms to accurately describe the true nature of matter/energy. Ultimately, if you want to understand quantum dynamics, you’ve got to learn to think in mathematical terms, and not using linguistic metaphors. Language will mislead you in this area. ---
**Author:** ![andy\_fl](https://avatars.discourse-cdn.com/v4/letter/a/49beb7/32.png) [@andy\_fl](https://boards.straightdope.com/u/andy_fl)\ **Post date:** [January 3, 2003, 4:01pm UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216/28 "2003-01-03T16:01:27Z")
Neither. IMNA Physicist - IMHO One of the things common in Relativity and Quantum Mechanics is “observer created reality”. So the photon (or light) existence is meaningless unless and until you try to measure it or it has some effect on you. And the moment you detect it, its properties change. If you try to see it as a wave it appears as a wave and if you see it as a particle it appears as a particle. Why is light like that ? There comes the Anthropic Principle of Physics - If it were any different then we would’nt be here to ask that question 😃 Believe me or not, I have heard that answer to many of the questions. ---
**Author:** ![g8rguy](https://avatars.discourse-cdn.com/v4/letter/g/7cd45c/32.png) [@g8rguy](https://boards.straightdope.com/u/g8rguy)\ **Post date:** [January 3, 2003, 4:05pm UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216/29 "2003-01-03T16:05:49Z")
[response to hijack] No, g8rguy is delibarately chosen, as if there’s one thing I’m not, it’s great [/response] That said, for what it’s worth, I do know where **scotth** is coming from, and most of the field theorists I’ve talked to prefer to regard photons as particles, when pressed to choose particle or wave. Of course, what they would really rather do is simply say that light is an excitation of the Maxwell vector field, but most people don’t find that a very satisfying answer for some reason. 😉 ---
**Author:** ![hajario](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hajario/32/171_2.png) [@hajario](https://boards.straightdope.com/u/hajario)\ **Post date:** [January 3, 2003, 4:08pm UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216/30 "2003-01-03T16:08:29Z")
> [@](#): > > \*Originally posted by g8rguy \* > \*\*[response to hijack] > No, g8rguy is delibarately chosen, as if there’s one thing I’m not, it’s great > [/response] > \*\* If you look at his location, the name makes perfect sense. Haj ---
**Author:** ![scotth](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@scotth](https://boards.straightdope.com/u/scotth)\ **Post date:** [January 3, 2003, 4:52pm UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216/31 "2003-01-03T16:52:51Z")
Not at all Mangetout. Stay with me a minute, and I will try to make my objections clear. Is gravity a force between two objects as Newton said or is it a distortion of space like Einstein says? In many instances, they give the same answer to a very high degree of accuracy. When things get hairy, Newtonian gravity begins to give increasingly wrong answers. Einstein’s gravity continues to work like a champ. Einstein’s view of world appears to be the correct one. But, that doesn’t make Newton’s view un-useful. Spacecraft are launched, eclipses are predicted, and they all happen as planned using nothing but Newtonian equations. It is much less time consuming and intuitive to work with Newtonian physics. But, the answers will be more accurate using Einstein’s methods. The point is that these systems are fundementally different from a “philosophical” point of view. The underlying mechanisms, the causes if you will, are different. Keep this idea in mind. Light has an interesting history in our understanding of it. It has gone through many revolutions. Our understanding of the fundemental nature of light has changed many times over the years. It was not too long ago when the light as waves became pretty much the universally endorsed theory. This came about when interference and other things were discovered with light that previously had only been understandable in terms of waves. That understanding held until around 1900. The photoelectic effect was a big problem, and led to the beginnings of quantum mechanics. QM forwards the idea of the dual nature of both light and matter. QM explained many more things, but still had its short comings. During the 40’s and 50’s QED got serious. QED completely explains every thing in nature except two things: Gravity and the forces at work inside the nucleus of atoms. Think about how much that encompasses. This includes all of chemistry, mechanics, optics, magnetism, and on and on and on. And within our ability to measure, it numerically predicts expected results for all of these things completely accurately. QED gets rid of the wave/particle duality. It is fundementally different philosophically. Light is particles. All the events that were previously understood as wave like are now understood in terms of particle action. Can you still get useful answers to questions with previous theories? Sure! But our fundemental understanding of what light **is** has changed. A guy designing a telescope generally uses nothing but classical optics and considers light in terms of waves. That isn’t what is really going on, but it is much simpler to work with and gives useful answers. Light as waves, and light as a wave/particle duality are useful steps on the way to understanding it more deeply and are still extremely useful for day to day engineering in the same way that Newtonian gravity is still what you will find implemented in any ballistic computer. Fundementally, it is a flawed understanding though. That doesn’t destroy its utility. QED says light is particles. Period. For at least 40 years, QED has provided answers that agree with experiment perfectly, and with no exceptions what-so-ever. ---
**Author:** ![WordMan](https://avatars.discourse-cdn.com/v4/letter/w/e8c25b/32.png) [@WordMan](https://boards.straightdope.com/u/WordMan)\ **Post date:** [January 3, 2003, 5:09pm UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216/32 "2003-01-03T17:09:12Z")
Jeez, **scotth** that came across as compelling - thanks for the analogies. I would appreciate other physicists or at least afficionado’s to comment if you get a chance. Obviously **Bonzer** it would be really helpful to get your perspective - I am hoping that this is more of a language thing than a philosophy thing, but “Light is particles” vs. “light exhibits wave/particle duality” seem pretty different. Is there a book regarding QED that a layman could read? ---
**Author:** ![scotth](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@scotth](https://boards.straightdope.com/u/scotth)\ **Post date:** [January 3, 2003, 5:26pm UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216/33 "2003-01-03T17:26:41Z")
> [@](#): > > \*Originally posted by WordMan \* > \*\*Jeez, Is there a book regarding QED that a layman could read? \*\* I would enthusiastically endorse QED by Richard Feynman. As I am learning this stuff on my own, and not being guided by instructors or really have anyone to even ask questions of, I found this book to be simply invaluable. I would have never understood any of the stuff in the complete treatments that I have gotten so far without the mental framework provided by this book. One of the brilliant things about this book (IMHO at least) is that when he shows you how something works in a simplified manner, he goes to great pains to point out that what you are learning at that moment is a simplified (incomplete) explanation and that there will be a more detailed and better explanation coming later. Anyway, I have a number of books on QED and they fall into one of three categories. 1. A popularization that never really leaves feeling like you got it. 2. A detailed account of what is really going on, minus the mathmatically techniques to really perform useful calculations in a reasonable amount of time (Feynman’s QED is the only book I have found in this category). 3. College texts that teach almost entirely from the working the math point of view with very little (or not enough for me, at least) explanation of what the heck this juggling of figures really represents, or why exactly you should do it that way. The Feynman QED book really gives one an understanding of what is happening, and makes the books in category 3 tremendously more intelligible. ---
**Author:** ![g8rguy](https://avatars.discourse-cdn.com/v4/letter/g/7cd45c/32.png) [@g8rguy](https://boards.straightdope.com/u/g8rguy)\ **Post date:** [January 3, 2003, 6:23pm UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216/34 "2003-01-03T18:23:07Z")
**scotth** , be aware that the _reason_ that the books in category 3 are written with lots of math and little phyiscal interpretation is that what they are trying to teach you how to do is to use the theory; they make no claim on teaching interpretation of the theory. And it’s right that they don’t, because one of the dirty little secrets of QED is that while using Feynman diagrams and interpreting them and all the rest can provide some insight and really quite accurate numbers, the fact is that it’s not actually right. The reason we do it that way is that it’s all we can really do; it’s a matter of convenience and of getting good answers, not of actually solving the problem correctly. ---
**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\ **Post date:** [January 3, 2003, 6:40pm UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216/35 "2003-01-03T18:40:17Z")
John Baez and Greg weeks are physicists of some renown. Here is what they think with regard to the particle/wave concept of the photon in QED. > [@](#): > > The general conclusion is that the particle concept is only of limited validity in quantum field theory. (That doesn’t mean that the “wave” concept is superior. What is superior is the quantum field concept, which is neither wave nor particle but has aspects of both. In fact, in the Feynman Lectures, Feynman is careful to answer the question “Is light like a particle or a wave” with “It is like neither”.) ---
**Author:** ![artemis](https://avatars.discourse-cdn.com/v4/letter/a/91b2a8/32.png) [@artemis](https://boards.straightdope.com/u/artemis)\ **Post date:** [January 3, 2003, 6:55pm UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216/36 "2003-01-03T18:55:02Z")
> [@](#): > > \*Originally posted by scotth \* > \*\*QED says light is particles. Period. For at least 40 years, QED has provided answers that agree with experiment perfectly, and with no exceptions what-so-ever. \*\* You keep saying that QED says that light is particles - it does not. That is a simplification used in popular books that attempt to “explain” quantum theory to laypersons (generally unsuccessfully). It’s no more accurate than saying “an electron is a negatively-charged particle orbiting an atom’s nucleus” (a phrase you’ll often see in introductory chemistry textbooks), when in fact, an electron in an atom is better described as a vector field centered on the atomic nucleus. **g8rguy’s** statement “light is an excitation of the Maxwell vector field” **is** accurate, but that phrase doesn’t conjure up an image in people’s minds the way "particle’ or “wave” does. The reason those textbooks in your category 3 don’t attempt to tell you “what is going on besides the math” is because in fact nothing IS going on besides the math. Quantum theory is **purely** a mathematical construct, and when you try to use visual or verbal analogies to “make sense” of it, you will be mislead. Our primate minds, which were designed to solve the problems encountered while swinging in trees, are not constructed to intuitively “get” quantum mechanics in the same way we can “get” Newtonian physics (to offer just one example). What you’re doing is the equivalent of asking “how much candy can we mine from the Big Rock Candy Mountain?”; the question is meaningless, even though it LOOKS like it should have a sensible answer. The “stuff” of the universe examined on the quantum level doesn’t fit into any categories that we are familiar with on the macroscopic level, such as “particle”, “wave”, “matter”, or “energy”. ---
**Author:** ![Scott\_Dickerson](https://avatars.discourse-cdn.com/v4/letter/s/f04885/32.png) [@Scott\_Dickerson](https://boards.straightdope.com/u/Scott_Dickerson)\ **Post date:** [January 3, 2003, 7:15pm UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216/37 "2003-01-03T19:15:38Z")
Artemis: “To attempt to view quantum phenomena using the semiotic tools we’ve devised to describe the macroscopic world is an excercise in futility. Our everyday language doesn’t have terms to accurately describe the true nature of matter/energy.” Yup! Everyone: One little point I don’t want to let slip by is the question of the relevance of “interpretation”, which really addresses the relevance of metaphysical philosophy. “It’s undoubtedly tempting to believe (the hope has ocurred to most of us) that all the philosophical arguments about quantum mechanics might be resolvable merely by focussing on field theory instead…” sayeth Bonzer; and I would guess the “us” is the community of active physicists. It would be an error to suppose, however, that metaphysical philosophers are in the position of having put their money on one horse or another. The dominant “it’s both, and neither” view is philosophically delicious and quite elegant, to such a degree that philosopher Hilary Putnam has suggested that we revise our standard treatment of basic logic in light of wave/particle duality, rather than force the universe into the Procrustean bed of our own preconceptions. If one interprets QED as denying that light has, necessarily, a wave nature as well as a particle nature–I’d be interested in learning how the interference-pattern phenomenon is explained, and on what basis the “particle-ists” discount the possibility that some ultracomplex field kinematics might give a particle-like appearance to what could also be interpreted as wave-overlays. But set all that aside– have we established PRECISELY what is to be meant by the terms “particle” and “wave”? ---
**Author:** ![bonzer](https://avatars.discourse-cdn.com/v4/letter/b/45deac/32.png) [@bonzer](https://boards.straightdope.com/u/bonzer)\ **Post date:** [January 4, 2003, 3:20am UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216/38 "2003-01-04T03:20:38Z")
> [@](#): > > \*Originally posted by scotth \* > This is Feynman in 1985 (20 years later). This is just a couple paragraphs before he begins explaining sum over histories. Damn, that’s a nice piece of late-Feynman exegesis - certainly better than my quote. On the other hand, I’m trying not to be dogmatic here. The fact that he changed his mind on the matter is largely irrelevant - the key point is that these issues are _arguable_. This isn’t **Great Debates** ; **WordMan** wanted clarification on his understanding and, in those circumstances, it’s hardly useful to present an extreme position as the final word, at least without some explanation. > [@](#): > > The problem is, that was discussing things in the simpler quantum mechanics framework, not the more complete QED framework. Actually, I think this is irrelevant. The argument that particles are detected as particles, full-stop, (be they photons, electrons or whatever) can be made in vanilla quantum mechanics. One might even argue that Einstein’s position in 1905 was just this. It’s also a position that’s certainly been held by a minority in the years since. For instance, there’s the example of the de Broglie-Bohm pilot wave interpretation. This is a purely quantum mechanical theory (it’s notoriously difficult to generalise to QFT) in which particles are just that that, always. And it’s utterly consistent. But that doesn’t meant that it’s a remotely popular position. Incidentally, I certainly second the suggestion that **WordMan** read as much Feynman (of whatever date) as he can lay his hands on ---
**Author:** ![scotth](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@scotth](https://boards.straightdope.com/u/scotth)\ **Post date:** [January 4, 2003, 4:09pm UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216/39 "2003-01-04T16:09:20Z")
> [@](#): > > \*Originally posted by bonzer \* > \*\ ***WordMan** wanted clarification on his understanding and, in those circumstances, it’s hardly useful to present an extreme position as the final word, at least without some explanation. > \*\* I quite agree here. My problem is that I couldn’t figure out how to summarize the 70 odd pages of text that really convinced me of this into something that I could type in here in a reasonable amount of time. In fact, I can’t see a way to condense the material hardly at all. I will offer another quote from the same book (QED, by Richard Feynman) that reinforces the light as a particle view and a couple others that will answer some of the other concerns. This one comes after the first run through of sum over histories. He is about to get into them in more detail. For example he demonstrates why/how figuring partial reflections with sum over histories gets the exact same answer when only considering the surfaces of the glass as when considering that the light interacts with the entire thickness of the glass. > [@](#): > > This strange phenomenon of partial reflection by two surfaces can be explained for intense light by a theory of waves, but the wave theory cannot explain how the detector makes equally loud clicks as the light gets dimmer. Quantum Electrodynamics “resolves” this wave-particle duality by saying that light is made of particles (as Newton originally thought), but the price of this great advancement of science is a retreat by physics to the position of being able to calculate on the _probability_ that a photon will hit a detector, without offering a good model of how it actually happens. This quote really tells the reader what exactly QED is (Maxwell’s theory made compatible with Quantum Mechanics). > [@](#): > > Because the theory of quantum mechanics could explain all of chemistry and the various properties of substances, it was a tremendous success. But still there was the problem of the interaction of light and matter. That is, Maxwell’s theory of electricity and magnetism had to be changed to be in accord with the new principals of quantum mechanics that had be developed. So a new theory, the quantum theory of the interaction of light and matter, which is called by the horrible name “quantum electrodynamics,” was finally developed by a number of physicists in 1929. This is particularly for some of Artemis’s objections, and I found the book quite lived up to this quote. > [@](#): > > In those days, only a few Maya priests could do such elaborate calculations. Now, suppose we were to ask one of them how to do just one step in the process of predicting when Venus will next rise as a morning star–subtracting two numbers. And let’s assume that, unlike today, we had not gone to school and did not know how to subtract. How would the priest explain to us what subtraction is? > > He could either teach us the numbers represented by the bars and dots and the rules for “subtracting” them, or he could tell us what he was really doing: “Suppose we want to subtract 236 from 584. First, count out 584 beans and put them in a pot. then take out 236 beans and put them to one side. Finally, count the beans left in the pot. That number is the result of subtracting 236 from 584.” > > You might say, “My Quetzalcoatl! What tedium–counting beans, putting them in, taking them out–what a job!” > > To which the priest would reply, “That’s why we have the rules for the bars and dots. The rules are tricky, but they are a much more efficient way of getting the answer than by counting beans. The important thing is, it makes no difference as far as the _answer_ is concerned: we can predict the appearence of Venus by counting beans (which is slow, but easy to understand) or by using the tricky rules (which is faster, but you must spend years in school to learn them).” > > To understand _how_ subtraction works–as long as you don’t have to actually carry it out–is really not so difficult. That’s my position: I’m going to explain to you what the physicist are _doing_ when they are predicting how Nature will behave, but I’m not going to teach you any tricks so you can do it _efficiently_. You will discover that in order to make any reasonable predictions with this new scheme of quantum electrodynamics, you would have to make an aweful lot of little arrows on a piece of paper. It takes seven years–four undergraduate and three graduate–to train our physics students to do that in a tricky, efficient way. That’s where we are gointg to skip seven years of education in physics: By explaining quantum electrodynamics to you in terms of hwat we are _really doing_, I hope you will be able to understand it better than do some of the students! Of course, none of that settles the OP. But, in my opinion, the first two chapters of QED gives the most lucid answer to WordMan’s original question that I have ever seen. I strongly encourage him to pick that book up. This is asking alot, but… It would be of great interest to me to get Bonzer to read the first 70 pages of this book and point out any specific failings for me. This would be of great value in selecting more material to learn. ---
**Author:** ![Scott\_Dickerson](https://avatars.discourse-cdn.com/v4/letter/s/f04885/32.png) [@Scott\_Dickerson](https://boards.straightdope.com/u/Scott_Dickerson)\ **Post date:** [January 4, 2003, 7:41pm UTC](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216/40 "2003-01-04T19:41:06Z")
In addition to my earlier questions, which seem to me ever more urgent, there’s this: Why is it particularly important to establish exactly what the talented Mr. Feynman really thought–as opposed to trying to establish more directly what sort of consensus presently obtains in the relevant portion of the community of physicists, and why? [Previous page](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216.md?page=1) [Next page](https://boards.straightdope.com/t/the-nature-of-light-particle-wave-both/146216.md?page=3)