Quoting Wavelength vs Frequency - Page 1
Forum section: electronics / rf-microwave

author: @rt
author_rank: Super Contributor
timestamp: October 31, 2019, 06:10:31 am
content: If radio waves don’t exist, why do we measure wavelength instead of frequency, like everything else? For anything below light, it occurs to me RF is the outlier here.

author: hamster_nz
author_rank: Super Contributor
timestamp: October 31, 2019, 06:21:39 am
content: Both are equally valid, but sometimes one is more handy than the other.In electronics the frequency is the important parameter (unless you get into GHz territory where things get real tricky... ). The formulas used all use frequency.If you are mostly building antennas, then wavelength is the important parameter, as it defines the approximate size of your antenna and associated structures.

author: @rt
author_rank: Super Contributor
timestamp: October 31, 2019, 06:25:01 am
content: I can certainly see the favour for an antenna, but historically amateurs had to build the whole radio, so there’s a VFO, mixer, filters, etc. all of which would require frequency as an input for equations.It occurs to me that an antenna design is the only useful place to make the conversion, and perhaps transmission lines, and feed systems, etc.

author: DaJMasta
author_rank: Super Contributor
timestamp: October 31, 2019, 07:55:56 am
content: Yep, antennas, transmission lines, feed systems, trace length, etc.Not sure if there's going to be one answer that is "correct", I think it's probably a combination of practical or historical reasons that pushed it a bit in the way we use today. Perhaps part is that wavelength has been constant but in the early days of radio it was Cycles per Second instead of Hertz. Maybe part of it is a crossover with light and others on the EM spectrum that are more typically wavelength than frequency. Maybe on a more fundamental level, the wavelength is a physical parameter of the wave while frequency is defined based on the wavelength - yes, you can convert back and fourth and frequency is often more useful, but when describing an electromagnetic wave, the wavelength is a more direct description.Maybe it's not a particularly compelling argument, but compounded as the de-facto for long enough, and that's plenty of an explanation for the convention to me.

author: hagster
author_rank: Frequent Contributor
timestamp: October 31, 2019, 08:23:50 am
content: Wavelength changes dependent upon the material properties. Frequencies remains constant. As such, I would say Frequency it the preferred measurement.We also only ever measure bandwidth in Hertz, so why make life difficult.

author: jadew
author_rank: Frequent Contributor
timestamp: October 31, 2019, 10:12:19 am
content: Quote from: @rt on October 31, 2019, 06:10:31 amWhat do you mean they don't exist?

author: @rt
author_rank: Super Contributor
timestamp: October 31, 2019, 10:28:24 am
content: Quote from: jadew on October 31, 2019, 10:12:19 amNothing more than that really. That a wave only exists on your scope because it’s graphed, but not in the air.

author: jadew
author_rank: Frequent Contributor
timestamp: October 31, 2019, 04:15:31 pm
content: Quote from: @rt on October 31, 2019, 10:28:24 amI see, so that's the source of the confusion. Well, it does exist in space too, if they wouldn't exist, they wouldn't propagate.

author: borjam
author_rank: Unknown
timestamp: October 31, 2019, 04:21:00 pm
content: The reasons are mostly historical.On HF and, in general, most ham bands at frequencies below several GHz, wavelength is used when speaking about a band (40 m band, 2 m band, etc) and frequencies when accuracy is needed "I will be listening on 7110 KHz". The same practice applied to short wave broadcasters when they said something like "We transmit daily on the 41 m band, 7250 KHz, 25 m band on 12350 KHz", etc.But you will never hear "on 41.379 metres" instead of 7250 KHz

author: AG6QR
author_rank: Frequent Contributor
timestamp: October 31, 2019, 05:04:34 pm
content: Quote from: borjam on October 31, 2019, 04:21:00 pmTrue. To underscore that, notice that the 40 meter band does not include the wavelength 40.000 meters, which is at a frequency of 7.4948 MHz.In practice, frequency is used for precision, wavelength for imprecise broad general ranges and dimensions of antennas and transmission lines.Oh, and radio waves most definitely DO exist.

author: @rt
author_rank: Super Contributor
timestamp: October 31, 2019, 05:42:18 pm
content: Quote from: borjam on October 31, 2019, 04:21:00 pmWell interestingly, the reason I thought to ask was because I have an old MW AM radio with wavelengths printed on the dial face instead of frequency,so if I had a friend in the 1930’s or so with the same radio, I would indeed tell him there’s some program on a particular wavelength (not talk about a band since there’s only one).It’s just incidental, that there’d probably only be one local station.Quote from: AG6QR on October 31, 2019, 05:04:34 pmNow I'm very interested, and have had this conversation more than once today.Please define a wave. Is that a mathematics model used to understand it,or a wave that has physical dimensions, and/or the appearance of a sinusoid if you could see it?Or something that really travels in a straight line that differs in amplidude along that line?

author: hamster_nz
author_rank: Super Contributor
timestamp: October 31, 2019, 06:13:47 pm
content: Regarding the existence of radio waves, there is most likely something cultural going on in this discussion. Of course they exist because light exists and radio works...Maybe for @rt 'exist' means 'directly observable' due to translation errors or misunderstanding ? As in light can be directly observed, but 101.7FM can't?That makes this discussion make sense...

author: borjam
author_rank: Unknown
timestamp: October 31, 2019, 06:14:54 pm
content: Quote from: @rt on October 31, 2019, 05:42:18 pmIt does exist, it's a disturbance. For anything to exist it doesn't need to be a physical object.Or it can be if you can describe it as photons

author: DimitriP
author_rank: Super Contributor
timestamp: October 31, 2019, 06:23:51 pm
content: Quote

author: ejeffrey
author_rank: Super Contributor
timestamp: October 31, 2019, 06:27:15 pm
content: Unless specifically qualified wavelength almost always means wavelength in vacuum anyway which makes it particularly annoying. It is just an awkward measurement of frequency.

author: radiolistener
author_rank: Super Contributor
timestamp: October 31, 2019, 06:34:06 pm
content: Quote from: @rt on October 31, 2019, 06:10:31 amradio wave exists. With no radio waves your cellphone and FM receivers won't workWe measure wavelength, because wavelength for the same frequency may be different. Because speed of light is different in different environment.The things even more diffucult, because speed of light also may depends on the frequency.

author: radiolistener
author_rank: Super Contributor
timestamp: October 31, 2019, 06:40:13 pm
content: Quote from: @rt on October 31, 2019, 10:28:24 amIn such way you also can say that voltage on the battery also doesn't exists, because it "only exists on your voltmeter"

author: @rt
author_rank: Super Contributor
timestamp: October 31, 2019, 06:48:43 pm
content: Quote from: radiolistener on October 31, 2019, 06:40:13 pmI don’t relate one to the other because I don’t deny radio works, and I do believe a field (or two) are radiated from an antenna, and that RF propagates into space. all of that.The key word is wave. I currently don’t believe that exists until you plot it on a graph of amplitude & time (as in a scope), and that actual RF radiates in straight lines from a source.PS. It’s also ok for me to be wrong, but I don’t think I’d chase down my sources until I’m understood.

author: radiolistener
author_rank: Super Contributor
timestamp: October 31, 2019, 06:53:43 pm
content: In short, frequency and wavelength are different things.And they have complex and very complicated dependency one from another. It is easy only for vacuum, because vacuum has no reactive component in it's impedance. But things are much more difficult for material which consists charge particles.And even for vacuum it is easy only if you don't take into account relativistic corrections. Because even vacuum properties is not constant, but the difference is so small, so you can just ignore it.

author: radiolistener
author_rank: Super Contributor
timestamp: October 31, 2019, 07:14:22 pm
content: Quote from: @rt on October 31, 2019, 06:48:43 pmDo you believe that water wave exists? Water waves are deformations propagation in the water.Do you believe that sound wave in the air exists? Sound waves are deformations propagation in the air.So, why you don't believe that radio wave exists? Radio waves are deformations propagation in the electric field.All these types of waves can be registered and measured. And all they can be verified that they have wave properties.What is the reason to not believe?

author: radiolistener
author_rank: Super Contributor
timestamp: October 31, 2019, 07:33:25 pm
content: Quote from: @rt on October 31, 2019, 05:42:18 pmjust imagine water. Try to kick it's surface, do you see waves from your kick?The same thing happens in antenna, when you kick electron back and forth in the wire.Electron is a charged particle and has electric field which is actually infinite and extends to the infinity of the universe.So, when you kick electron, its electric field needs to be shifted.But since speed of light is limited, electron's field cannot be updated at single moment for infinite distance.When you kick electron, it's electric field is deformed, and this deformations propagates into universe infinity with a speed of light. This electric field deformation propagation is electromagnetic waveBut the speed of light depends on properties of environment. For example, in water and in air speed of light are different. It leads to reflections at the border between different environments. This is why light refracts at the border between air and water. The same thing happens with radio waves, because light is also radio wave, but with very high frequency.Since speed of light depends on environment, the wavelength for the same frequency will be different for different environment.For example wavelength in coax cable is about twice shorter than wavelength in the air for exactly the same frequency.Actually the things are more complicated, because wave propagation speed in coax cable depends on the frequency.

author: AG6QR
author_rank: Frequent Contributor
timestamp: October 31, 2019, 07:57:12 pm
content: Quote from: @rt on October 31, 2019, 05:42:18 pmI'd say a wave is anything that obeys the wave mechanics taught in first-year physics classes. It diffracts, it produces interference patterns, it reflects (though particles can also reflect sometimes), it refracts, etc.The dual-slit experiment proves that radio waves are waves, and don't just travel in simple straight lines from source to destination. I'm aware of their particle nature, as well, but I don't see that demonstrated at radio frequencies as often as I see the wave nature.The alternating nulls and reinforcements observed under multipath conditions are another phenomenon that is hard for me to explain without invoking the wave nature of radio waves.

author: radiolistener
author_rank: Super Contributor
timestamp: October 31, 2019, 08:08:33 pm
content: Quote from: AG6QR on October 31, 2019, 07:57:12 pmParticle nature is proven for interaction between particle and electromagnetic wave, not for electromagnetic wave itself. This duality is not a property of electromagnetic wave, this is a property of interaction between electromagnetic wave and particle. When there is no particle, electromagnetic wave has clean wave properties

author: hamster_nz
author_rank: Super Contributor
timestamp: October 31, 2019, 08:40:33 pm
content: A question to ponder:There are no waves in an empty pond. If you "tap your foot" into a vacuum, where you will create no ripples, as there is no medium to transfer the energy.How is it then that we see light from the sun? Through what medium does the energy flow?

author: jadew
author_rank: Frequent Contributor
timestamp: October 31, 2019, 08:52:56 pm
content: Quote from: hamster_nz on October 31, 2019, 08:40:33 pmI'm not a physicist, so I may be wrong, but the way I think the universe is understood at the moment, is that it's made up of many fields, and vibrations in those fields generate things, and some of the vibrations in some of the fields can interact with vibrations from other fields.In this case, RF energy is a vibration in the EM field.Edit: Not sure if "generate things" is the right choice of words there, but what I wanted to say is that some of those vibrations seem to have observable manifestations, like magnetism and matter.

author: ejeffrey
author_rank: Super Contributor
timestamp: October 31, 2019, 10:44:06 pm
content: Quote from: radiolistener on October 31, 2019, 08:08:33 pmThat is not correct. While the photoelectric effect (one of the key experiments motivating the development of quantum mechanics) can be described in terms of interaction of a purely classical EM wave interacting with a quantized detector, other experiments show the clear quantized quantum mechanical behavior of light. To most properly show the quantized nature of light you need to look at emission process not just detection. For instance a single atom in an excited state can decay back to the ground state, emitting a photon. When it does it always emits exactly 1 photon. If you try to describe the behavior of the emitted light with a classical wave you will get the wrong answer.

author: radiolistener
author_rank: Super Contributor
timestamp: October 31, 2019, 11:55:52 pm
content: Quote from: ejeffrey on October 31, 2019, 10:44:06 pmYou're wrong. Radiation does not consist of particles, and the classical, i.e., non-quantum, limit of Quantum Theory of Radiation is described by Maxwell's equations for the electromagnetic fields, which do not involve particles.Regarding to emission, you can read this article for example:- "Classical Laser" by M. Borenstein, W.E. Lamb, Jr.: Phys. Rev. A 5, 1298 (1972)it shows that a laser could be completely classical.Another example Quantum Theory of Radiation appeared in 1967, and no particles like "photons" appeared in it at all.There is a lot to talk about the wave-particle duality in discussion of quantum mechanics. This may be necessary for those who are unwilling or unable to acquire an understanding of the theory. However, this concept is even more pointlessly introduced in discussions of problems in the quantum theory or radiation.Here the normal mode waves of a purely classical electrodynamics appear, and for each normal mode there is an equivalent pseudo-simple harmonic-oscillator particle which may then have a wave function whose argument is the corresponding normal-mode amplitude. Note that the particle is not a photon. One might rather think of a multiplicity of two distinct wave concepts and a particle concept for each normal mode of the radiation field. However, such concepts are really not useful or appropriate.

author: tomato
author_rank: Regular Contributor
timestamp: November 01, 2019, 02:02:08 am
content: Awesome thread; we've gone from "radio waves don't exist" to "radiation does not consist of particles." I can't wait to see what's next ...

author: @rt
author_rank: Super Contributor
timestamp: November 01, 2019, 02:13:11 am
content: Quote from: tomato on November 01, 2019, 02:02:08 amAnd I’m fine with it, because the other topic is far more important, and interesting to me than the original one.I don’t believe what I believe because I’ve experimented with it, or done some maths on paper,but because I was taught it by someone in authority, and then had the same information backed up by a Scientist, and maybe two (depending on how I interpret the second one's replies).So whether I’m right or wrong there’s a problem either way.Let me ask, is RF a wave of physical dimension when you send it through the core of your coax on the way to your feed point?and if so, how is it travelling on the surface of the centre conductor with the sheath surrounding it? or when it’s propagating on a copper trace on a PCB?

author: radiolistener
author_rank: Super Contributor
timestamp: November 01, 2019, 02:43:27 am
content: Quote from: @rt on November 01, 2019, 02:13:11 amEM wave traveling in the insulator of coax cable between center conductor and braid.It's very similar to the light which is traveling in the fiber of optical cable.Conductors of coax cable working like mirror for EM wave, they keep EM wave inside cable.Quote from: @rt on November 01, 2019, 02:13:11 amon a copper trace of PCB it is traveling almost the same as in coax cable - in the insulator between copper trace and ground (or between two copper traces for symmetric line).If you cannot imagine it, there is a nice visualization which may help you

author: hamster_nz
author_rank: Super Contributor
timestamp: November 01, 2019, 02:58:33 am
content: Quote from: @rt on November 01, 2019, 02:13:11 amI don't think it is a valid question. a bit like "What colour of dog is that fish?"

author: @rt
author_rank: Super Contributor
timestamp: November 01, 2019, 03:13:18 am
content: Ok, the video I get. I’d use, and have used a wave to describe radio myself, and have watched many videos about it (though not the particular video you linked).I might as well take an antenna that doesn’t exist as well, because we also use that to describe something.If it were a dipole we’d have introduced a distorted field loop shape depending on the antenna’s radiation pattern.So if the example can be isotopic, and the radiation pattern, a sphere, where is the wave there?If the GIF doesn’t animate, the thread it came from appears to very much contradict information in this thread (but actually isn’t one of my sources in the first place).https://electronics.stackexchange.com/questions/144326/do-we-know-what-a-radio-wave-looks-likeWhether or not you agree with this, do you see somehow a wave in there? or is it trying to illustrate an infinite number of lines from the point source? or something else?

author: CatalinaWOW
author_rank: Super Contributor
timestamp: November 01, 2019, 03:26:25 am
content: I find it difficult to visualize or understand the behavior of waveguides (particularly including stubs, forbidden modes and the like) without wave behavior. Same thing with reflections from discontinuities in coax. Do you have some non-wavelike way of understanding, predicting and analyzing such phenomena?You mention your difficulty in imagining a wave without a medium in the vacuum of space. This was one of the great conceptual breakthroughs of the 19th century. Most physicists of the era felt the way you do and even named the medium, the luminiferous aether. Much of experimental physics was directed at trying to measure the properties of this aether. Then Michelson and Morley proved with their famous experiment that such an aether could not exist.Nothing in Maxwell's equations requires a medium. They merely describe a relationship between the magnetic and electric fields, charge and current. The equations have similar form and behavior to equations describing sound and water waves so the wave description is very natural. But if you don't like calling them waves you don't have to. You won't convince the vast majority of us who find the description compelling and useful.

author: @rt
author_rank: Super Contributor
timestamp: November 01, 2019, 03:30:46 am
content: I should also ask if both of these could be considered a wave, or just the top one.The bottom one has no physical dimension to make a wave, but I might still call it a wave because something is changing and wave like.Forgive that the colours of both should gradually change, rather than hard change from one colour to the other.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: November 01, 2019, 03:53:05 am
content: Quote from: @rt on November 01, 2019, 03:13:18 amReading through the referenced stackexchange thread I was reminded of the story of 10 blind men describing an elephant. Each accurately described the piece he touched and felt (the trunk being like a hose, the tail like a brush and so on) while none really put together the whole picture. All of the descriptions are sound and all will help some visualize what is going on, but some integration is required to get the whole picture.The gif doesn't animate on my system, but I would assume that it either shows an expanding sphere or a color changing sphere of constant radius. It is really hard to to capture a four dimensional phenomena (x,y,z,t) in a two dimensional picture, even if you give it a time dimension. But you can get a good idea by analogy. If you take a shallow tray of water and put a steady stream of drops into the center, you will see a circular pattern of waves expanding from the point where the drops hit. If you could stop time and measured the height of the water along a radial path you would find a sinusoidal pattern. The water doesn't propagate, the only thing that moves is the location of the peaks. Which move outward over time. It is really worth setting up a cookie tray and duplicating the water wave experiments shown in many beginning physics texts. You can directly observe diffraction around obstructions of various shapes, the interference between two slits, conversion of a plane wave to a spherical wave by an aperture, the lack of lateral motion of the water in these waves and many other things that give a more intuitive understanding of the phenomena than most people can get from playing with the equations, and even today it is faster and easier to set up than most computer simulations.Now in the spherical rf source case (a thought experiment only since the you can only approximate this in reality), instead of the waves being vertical amplitude in a two dimensional space the waves are field strength in three dimensional space. The places where E or H fields reach their maximum in a specific direction (toward the source for example) at a specific point in time form spheres. If you plot the field amplitude at that time along a radial path you find a sinusoid. The peaks move outward over time (the spheres expand) at the propagation velocity, c. Wavelike behavior.

author: radiolistener
author_rank: Super Contributor
timestamp: November 01, 2019, 03:54:39 am
content: Quote from: @rt on November 01, 2019, 03:13:18 amyou can see how dipole antenna works on my avatarHere is animated gif (click to view).The dipole is placed vertically at the center of picture with very small size, so you can see a big picture around dipole.I think this video will be useful for you:

author: DimitriP
author_rank: Super Contributor
timestamp: November 01, 2019, 04:21:19 am
content: Quote from: @rt on October 31, 2019, 06:10:31 amIgnoring the existence of waves confusion for a moment (yours),anytime you see a frequency formula, substitute with 1/299792458 m/s after a couple of days come back and tell us how much fun that is

author: DimitriP
author_rank: Super Contributor
timestamp: November 01, 2019, 04:36:59 am
content: Quote...assuming elephants exist...

author: AG6QR
author_rank: Frequent Contributor
timestamp: November 01, 2019, 05:00:22 am
content: Quote from: @rt on November 01, 2019, 03:13:18 amIf you can show me a real-world isotropic antenna, then I'll concede that radio waves don't exist in the real world.But you can't and I won't. It's the isotropic antenna that doesn't exist except as a fictional idealized construct of a textbook writer, like a massless string threaded through a frictionless pulley.

author: @rt
author_rank: Super Contributor
timestamp: November 01, 2019, 05:00:58 am
content: Quote from: DimitriP on November 01, 2019, 04:36:59 amPlease refrain from creating a strawman, because I think everyone in the thread knows that I believe radio waves exist.I’m only talking about what that would look like if you could actually see the E&H, or for simplicity, just the E.I’m also not trying to antagonise anyone, or ignore anyone, even if it appears that way.It’s quite the opposite. I’ve received conflicting information, even throughout the course of this thread, from elsewhere.One would think after 10 years something so fundamental would be widely known, at least in amateur radio circles, but what I can state as fact is that it is not.

author: @rt
author_rank: Super Contributor
timestamp: November 01, 2019, 05:01:54 am
content: Quote from: @rt on November 01, 2019, 03:13:18 amOf course.

author: radiolistener
author_rank: Super Contributor
timestamp: November 01, 2019, 05:17:09 am
content: Quote from: @rt on November 01, 2019, 05:00:58 am

author: CatalinaWOW
author_rank: Super Contributor
timestamp: November 01, 2019, 05:24:52 am
content: Quote from: @rt on November 01, 2019, 05:00:58 amI would love to help, but am a little confused as to what you are looking for. Part of the problem may be that while the visualization is fairly simple in a couple of ideal cases, it really is complex in the much of the real world. In the distant far field, or for the ideal isotropic radiator of an unmodulated carrier it really is expanding spheres. Showing how the fields change over time is tough because of the number of dimensions, but a simple view could use one color for peak E and another for peak H, and the expanding spheres would alternate colors. Expand that to show one color fading sinusoidally into the other and you are closer yet. Modulating the carrier adds to the fun. In all of these cases visualization requires taking a cross section or slice or making the transparency of each wave vary. Those attempts to look into what is a space filling set of fields is where much of the confusion comes from.The other simple case is the first mode in a waveguide. Texts such as Ramo, Whinnery and Van Duzer or Plonsey and Collins show good illustrations of this simple case and some of the higher modes and variations.As soon as you look at multipole antennas, multipath, distributed apertures and the like it gets very messy. Just as real waves in the ocean don't march in nice straight lines or simple circular expansions. They are pretty chaotic.

author: radiolistener
author_rank: Super Contributor
timestamp: November 01, 2019, 06:33:32 am
content: I think these animations will help to understand what happens with E and H fields around dipole antennaThe purple arrows are electric field vectors, blue arrows are magnetic field vectors.More close:

author: ejeffrey
author_rank: Super Contributor
timestamp: November 01, 2019, 02:39:23 pm
content: Quote from: @rt on November 01, 2019, 03:30:46 amBoth of those are representations of waves. Transverse variation is not an important quality of waves.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: November 02, 2019, 09:11:54 am
content: Bit late, but There is clear evidence of waves at RF frequencies behaving as particles too. Just look at masers or atomic/molecular clocks. These all rely to some extent on the particle-nature of waves, and can work well into the millimeter-wave and RF frequency ranges.And single-mode optical fiber is a clear indicator of the wave-nature of EM in the IR/visible spectra. You can't explain waveguide modes purely with particle behavior.

author: radiolistener
author_rank: Super Contributor
timestamp: November 02, 2019, 03:21:15 pm
content: Quote from: TheUnnamedNewbie on November 02, 2019, 09:11:54 amof course you cannot explain it with purely particle or purely wave behavior, because it involves interaction between both - particles and EM wavesJust remove particles from experiment and try to explain why EM wave itself needs to have particle behavior and where did you seen such particle behavior of EM wave in the vacuum? I mean, when there is no interaction with particles.EM wave has pure wave nature and described with Maxwell's equations, which don't involves particles at all.

author: tomato
author_rank: Regular Contributor
timestamp: November 02, 2019, 04:28:02 pm
content: Quote from: radiolistener on November 02, 2019, 03:21:15 pmDouble slit experiment shows particle behavior.

author: radiolistener
author_rank: Super Contributor
timestamp: November 02, 2019, 05:06:27 pm
content: Quote from: tomato on November 02, 2019, 04:28:02 pmYes, and this confirms that EM wave has pure wave behavior.Double slit experiment is interaction between EM wave and particles. EM waves don't interacting with each other, particles do.When you experimenting with interaction between particles and EM waves this is pretty obvious that you will get properties of both behaviors.You cannot discard Maxwell's equations with any kind of experiment

author: tomato
author_rank: Regular Contributor
timestamp: November 02, 2019, 05:46:16 pm
content: There are many experiments that establish the wave-particle duality of electromagnetism. Yes, they all involve interaction of electromagnetism with "particles", i.e. matter, because that is the only way we can get information about the nature of electromagnetism. Your argument that, in the absence of these interactions, there is no evidence for the particle nature of electromagnetism is hollow; in the absence of these interactions there is also no evidence for the wave nature of electromagnetism.

author: radiolistener
author_rank: Super Contributor
timestamp: November 02, 2019, 06:16:19 pm
content: Quote from: tomato on November 02, 2019, 05:46:16 pmWave-particle duality concept is pointlessly. Discussion about wave-particle duality may be necessary for those who are unwilling or unable to acquire an understanding of the theory.EM wave is described with Maxwell's equations and it doesn't involves particles at all.It works well and I'm sure, there is no even one experiment which can discard it.Just because such experiment will cancel all classic electrodynamics

author: tomato
author_rank: Regular Contributor
timestamp: November 02, 2019, 06:23:36 pm
content: Quote from: radiolistener on November 02, 2019, 06:16:19 pmThere are a lot of physicists (including several Nobel Laureates) working in the field of quantum optics that will be very disappointed to hear that they don't understand the theory.

author: radiolistener
author_rank: Super Contributor
timestamp: November 02, 2019, 06:40:16 pm
content: Quote from: tomato on November 02, 2019, 06:23:36 pmThey don't saying that EM wave consists of particles, so I don't see reason why they should be disappointed.If you're talking about quasi-particles which are used to simplify model of complex interactions, that is okay. But waves and particles are completely different things. For example phonon (quantum of sound wave in the crystal) is not equals to atom or molecule. This is just a property of complex interactions between atoms in the crystal.

author: tomato
author_rank: Regular Contributor
timestamp: November 02, 2019, 07:04:31 pm
content: Quote from: radiolistener on November 02, 2019, 06:40:16 pmThe field of quantum optics is based on electromagnetic waves consisting of particles (photons).

author: radiolistener
author_rank: Super Contributor
timestamp: November 02, 2019, 07:55:14 pm
content: Quote from: tomato on November 02, 2019, 07:04:31 pmPhoton is a quantum of EM wave energy. The same as phonon is a quantum of sound wave energy in solid-state body. You can use quasi-particles to simplify model of very complex particle interactions. That's okay. Just an abstraction. To be more clear, phonon is not equals to an atom. These are different things.Talking that EM wave consisting of particles is something like to say that a car consisting of kilometers (miles) of road

author: tomato
author_rank: Regular Contributor
timestamp: November 02, 2019, 08:54:21 pm
content: Quote from: radiolistener on November 02, 2019, 07:55:14 pmPoorly conceived analogies do not make for a good argument.

author: radiolistener
author_rank: Super Contributor
timestamp: November 03, 2019, 12:56:34 am
content: Quote from: tomato on November 02, 2019, 05:46:16 pmthat's not true. You can check EM wave behavior by monitoring what happens with light in a free space. Yes, it requires interaction with matter, but only at some point, so you can take it into account.There is no evidence that EM wave has particle behavior in absence of matter. We can see that the light from very far stars has pure wave behavior. And it pretty well corresponds with Maxwell's equations.Even for interaction with matter, photon is not required, these things can be explained with using only a classical time-dependent electromagnetic field.

author: tomato
author_rank: Regular Contributor
timestamp: November 03, 2019, 01:22:45 am
content: Quote from: radiolistener on November 03, 2019, 12:56:34 amActually, the light from distant stars is so faint that individual photons can be detected.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: November 03, 2019, 01:23:59 am
content: Viewing of stars does not resolve the wave-particle duality question. Photoelectric effect and photon anti-bunching are two phenomena that are hard to resolve with a purely wave viewpoint. But the truth of it is, none of us knows the underlying reality. We as a species are still very much in the dark on how the universe works. We have unexplained things like dark matter and dark energy which are fudge factors to make the equations match the observations. One or both of these may turn out to be much like the epicycles of medieval astronomy, a mathematical trick which sort of works but is not close to the real answer. Same thing applies to our wave and particle descriptions of EM radiation.I'm an engineer and like to use the easiest tool to answer a particular problem. I'll leave the questions about what is "real" to the philosophers. And the particle view is the easy path for one class of problems. The wave path for another. Both belong in your toolbox.

author: radiolistener
author_rank: Super Contributor
timestamp: November 03, 2019, 01:38:23 am
content: Quote from: tomato on November 03, 2019, 01:22:45 amYou can detect just some properties of EM wave energy absorption by matter particle. Nothing moreQuote from: CatalinaWOW on November 03, 2019, 01:23:59 amG. Wentzel and G. Beck in 1926 showed that the new quantum theory could describe the photoelectric effect correctly, without any use of "photons" or light quanta, using only a classical time-dependent electromagnetic field. More detailed calculations on the atomic photoelectric effect is done in H. Fearn, W.E. Lamb, Jr.: Phys. Rev. A 43, 2124 (1991)Near the end of his life Albert Einstein wrote, "All the fifty years of conscious brooding have brought me no closer to the answer to the question: What are light quanta? Of course today every rascal thinks he knows the answer, but he is deluding himself."

author: tomato
author_rank: Regular Contributor
timestamp: November 03, 2019, 02:37:55 am
content: Quote from: radiolistener on November 03, 2019, 01:38:23 amIndividual photons can be detected from distant stars. Your sentence is non-sensical.QuoteThe ability of semiclassical theory to explainsomequantum effects does not imply quantum theory is incorrect.QuoteEinstein's comment does not imply photons do not exist.

author: radiolistener
author_rank: Super Contributor
timestamp: November 03, 2019, 03:13:39 am
content: Quote from: tomato on November 03, 2019, 02:37:55 amWhen "photon" word was invented by G. N. Lewis in 1926, he think that the transmission of radiation from one atom to another was carried by a new particle, for which he coined the name "photon". This was to Lewis a real particle which could be bound to an atom. He specifically denied that it was the "light quantum" of Planck, Einstein and Bohr. In his meaning photon be the source, and sink, of Maxwellian radiation.Did you mean that "photon" or something else?Quote from: tomato on November 03, 2019, 02:37:55 amI didn't said that quantum theory is incorrect. You can use quasi-particles for abstraction of something more complex and it works. But this is just an abstraction.For example, quasi-particle "phonon" is used for quantized vibrations in a solid. You can use such model and it works pretty well. But there is no particle "phonon" in reality. This is just an abstraction.Quote from: tomato on November 03, 2019, 02:37:55 amyes, he didn't talked about "photons", he talked about "light quanta".And quantum effect for emission and absorption really exists. But it doesn't means that EM wave consists of particles. EM wave itself is pure wave and described by Maxwell's equations. And it don't needs to involve particles.

author: tomato
author_rank: Regular Contributor
timestamp: November 03, 2019, 03:27:19 am
content: Quote from: radiolistener on November 03, 2019, 03:13:39 amI use photon as it is used everyday by physicists working in quantum optics. The meaning given to the term in a paper written more than 90 years ago has little relevance.QuoteYou keep drawing analogies with phonons, but the analogy is meaningless. Phonons have little in common with photons -- they just have similar names.QuoteWhat he called light quanta are what modern physicists call photons. Regardless of the terminology, his statement did not imply the particles did not exist.

author: radiolistener
author_rank: Super Contributor
timestamp: November 03, 2019, 03:37:51 am
content: Quote from: tomato on November 03, 2019, 03:27:19 amso, when you said "photon" you're mean quantum of electromagnetic wave energy which can be emitted or absorbed by matter particle. Is that correct?

author: tomato
author_rank: Regular Contributor
timestamp: November 03, 2019, 04:08:25 am
content: Quote from: radiolistener on November 03, 2019, 03:37:51 amThere's a bit more to it than that. Do you have a good book on quantum optics?

author: radiolistener
author_rank: Super Contributor
timestamp: November 03, 2019, 04:35:11 am
content: Quote from: tomato on November 03, 2019, 03:27:19 amQuote from: tomato on November 03, 2019, 04:08:25 amI read some interesting article of known American physicist who worked in quantum optics and won the Nobel Prize in Physics.His specialization is Laser Theory, Quantum Optics, etc.Here are quotes from Abstract and Summary sections of his article.Just interesting, what is your thoughts about it?

author: tomato
author_rank: Regular Contributor
timestamp: November 03, 2019, 05:20:29 am
content: Quote from: radiolistener on November 03, 2019, 04:35:11 amWillis Lamb was a great man, and his contributions to the world of physics were enormous. I met him briefly, at a conference in Santa Fe in 1991, where we were lecturing in the same session. I remember feeling a great sense of sadness during his talk, as it was pretty obvious his best years were behind him. I will never say anything negative about him.

author: hamster_nz
author_rank: Super Contributor
timestamp: November 03, 2019, 07:02:06 am
content: Quote from: radiolistener on November 03, 2019, 04:35:11 amI feel that there are two perspectives from which to view the same underlying process. I am not surprised that thay can agree nearly all the time.I liken it to using epicycles for calculating the position of the planets in the night sky. It works, and can be made to be as precise as needed by adding more and more cycles on cycles and finer tuning of constants.However mapping the problem of the position of planets in the night sky into a 3D space, then using Newtonian gravity to give you the answer you are seeking, and then projecting back to the viewer's nights sky is a far more general solution, and can predict much more, like the paths of comets and asteroids. When Newtonian Gravity was giving wrong answers it was used to discover unknown planets, something epicycles couldn't do.If today an astronomer was to do great work while using epicycles as their framework it doesn't make the epicycle model any more valid...