studiot

I didn't say you did. The model was proposed (and dismissed) by the OP, then reintroduced by the OP in the form of a quote from a Wiki article. Do photons not originate at a photon source? Can they actually originate anywhere else ? I repeat a slit is not a photon source. If it were you could remove any other photon source from the experiment. I also note that most sources have some form of conditioning device(s) to focus or spread or otherwise produce the desired light distribution pattern. Which is consistent with the wave model, not the photon model and does indeed make the space between the slit walls into new sources. But it does not say that photons constantly disappear and reappear as new photons as the light progresses. But I'm sure you know all this.

Apart from fan heaters designed by marketing departments just so they can offer something differenct, most are of the of the cylindical type. Mount a series of these one one top of the other with their axes vertical if you must and you have a ready made wall of generators that does not disturb the airflow in the way an airofoild blase does. Aerofoils produce jets, which involve turbulence. The energy of turbulence air is not avialable for extraction. If mounted one behing the other in the airstream obviously the each succeeding genertor, however it is mounted, will suffer reduced performance relative to its predecessor since the predecessor reduces the wind speed somewhat. That is where the energy comes from. It is recovery from this reduction of windspeed that requires the spacing of the turbines. As I understand the proposal the 'turbines' are of the vertical axis cylinder type, mounted one deep in the wall so this effect will not be evident. The main reason for the lower efficiency of vertical axis machines is that the diameter that can be supported is limited substantially compared to horizontal axis machines. And it is the diameter of the tip that determines the maximum speed and therefore output. I have already mentioned this in a previous post.

When I said everything I included the source. If you are going to propose a model where photon 'bullets' are fired through the slots then you have to demonstrate the complete path from start of the bullet to impact with the detector. The Wiki article was just poorly worded. The objectional word is originate, not appear or 'behaves as if'. WE all do it and bangstrom has already pointed out that my textbook has also done it in talking about polarisation. However with smart alec way every response is being presented, I don't feel inclined to continue developing the discussion further.

Perhaps you should revise your aerodynamic theory ? With laminar flow there is no interference between the units. A lot of smaller units have the advantage over one big one in the event of a unit breaking down / needing servicing electricity supply is hardly interrupted. One big one is an 'all your eggs in one basket' situation.

I don't agree. If that were the case then you could remove everything before the slit barrier and 'photons' would still 'originate' from the slits.

You don't seriously expect me to continue our conversation, following that reply do you ?

Wiki is not always accurate. Photons do not 'originate' from slits.

No thanks for several offers of help then with your editing problem. Goodbye and close the door on your way out.

I also meant to say that phase is one of the important basic characteristics of all waves, shape is another and strength is a third. Simple plane waves have the characteristic of not loosing strength they propagate because they don't spread out.

BLANK well who'd have thought that. Drag and drop works. But fine control (positioning within 3 lines) is impossible.

I will try that, I have never found a way to move down the top quote short of using cut, followed by typing something in, followed by pasting the quote back in below the new typing.

70 something posts into this thread an it sounds like you are actually asking a question, instead of laying down incorrect law. Progress. So you have been told that light is a transverse wave (swansont again). The point of using planar waves in the models is that they don't spread out. They are particularly simple to work with because the three dimensions can be separated mathematically. All segments of the wavefront have the same direction of propagation, and all the oscillatory action take place in planes that the line of direction is normal to. Each plane is a plane of constant phase. A

No one is being silly. My heat pump vanes can quite easily ice up when there is no snow or ice about, due to quite low speed air movements through them. Microgeneration. Yes, that is why the diameter of these huge wind tubine rotors is so large. I wonder how thick the 'wall' need to be to generate any electricity from any reasonable wind speed, after overcoming friction of course.

So press return before entering the quote to generate a blank line. That's what I do.

Since you have used equality in your definition of Mathematics, what is the Science that defines equality for us, to prevent your definition becoming self referential ?

A climate activist cycles out to fix it. https://www.thenational.scot/news/19667986.stunt-cycling-star-danny-macaskill-wind-turbine-challenge-climate-change/

Agreed. But from the article. Nonsense. Even in the windiest place on Earth there are periods of calm. But why stand it on the ground ? A good safe place might be built into the gable end under a pitched roof. Or simple erected on top of a flat roof. Wherever it is placed there would need to be a store capable of holding the a predicted numbers of days usage in calm weather. In the UK building codes have maps showing isopleths that could be used for design purposes, as they already are for structural purposes. Final thought. What happens when they ice up ?

This might help

I have already confirmed that you understand I am referring to the wave approaching the slits from the source, by specifying in that space. As with diffraction and interference, there are differences between polarisation and planarity (plane waves), and coherence. Some waves cannot be polarised, but can still come in planar form, for example longitudinal waves. I'm suprised you respond to my specifying a plane wave by offering a laser, since as swansont has already noted, they are not plane sources. I agree that small optical lasers yield granular images on screen, though if you had an integrating screen over time you would achieve even illumination. True plane waves would indeed illuminate a detector screen evenly. In fact I do not know of any light sources that directly emit plane waves. Most light sources approximate to point sources (there are no true point sources). Such sources usually generate circular or spherical waves. A good guide to the type of wave is the shape of the wavefront - linear, circular, spherical etc. These have to be generated by special conditioning of the light from the source. So, if you do not know the reason for working with them, it would be suprising that you do not ask. The Arago experiment you referred to (the bright centre dot) is shown by Wiki to employ a point source. Do you think there would also be a dot if the waves were planar ? https://en.wikipedia.org/wiki/Arago_spot However Arago is also known for lots of careful experiments in collaboration with Fresnel using plane waves. All of this shows, as we have been telling you, that light has some wave character, some corpusucular character and some quantum character and possibly some additional characters as well.

Obviously you missed my response as it contained the answer to your original question.

So what ? How does that disagree with what I said and where exactly did I say you could ?

But we do call it yellow. yolk is Old English for yellow. (they spelt it geolca) pun intended.

I didn't think I'd ever give a +1 for cheating but there you go. You did however start correctly, hopefully you are not too drunk to finish it correctly.

Thank you for your answers to the questions. Yes I think from your answers you have correctly understood the questions. However you questions demonstrate that you need to understand the basics better. This is not a personal criticism but an attempt to help you. Diffraction and interference are different phenomena. Interference ony occurs when two separate waves overlap (occupy the same space). Changes of direction (spreading) of the waves is not involved. Diffraction is the result of a single wave interacting with a wave blocking object. It is the name given to the spreading of (single) waves when they pass through apertures or around objects. Until recently it has not been possible to show interference from two different light sources, but has been possible with other waves. That is way classical interference experiments split the light from a single source. The slit(s) experiment require a single plane wave in the space between the source and the slit(s) barrier. So interference is not possible or observable in that space. Insertion of an observation screen will show an even illumination. Insertion of a blocking object may show diffraction effects around its edges or in its shadow zone. With a single slit, the result of the passage of the wave depends upon the geometry of both the wave and the slit. Some results are also dependent upon the distances of the source and observing screen from the slits. For instance this distinguishes Fraunhofer and Fresnel diffraction. All of these phenomena are well tested experimentally, some have been known for hundreds of years. As regards the difference between the wave and photon models of light consider the quantity I, the intensity of illumination at any point on the screen. We have for photons [math]I = nh\nu [/math] And for waves [math]I = {\varepsilon _0}c{E^2}[/math] The key point here is that for either model the I must be equal as they refer to the same observable quantity.

Yes Markus has nailed it. I was wondering whether to recommend the Beiser book to you anyway but here is the contents page. Note carefully that his choice of chapters and their order. 1. 2. Particle properties of waves. 3. Wave properties of particles. 4. It really is a well thought out book. In particular it describes the observations and experiments that led to the 'quantum theory of light' really well. So let me ask you some simply physics question. In the single slit or double slit experiment, is diffraction or interference possible in the region before the slit barrier i.e. can diffraction or interference be observed ? Are both interference and diffraction possible in a) The single slit ? b) The double slit ?