Constructive and Destructive Interference

1) One of the main arguments in favor of constructive and destructive interference is presented in a very understandable language by the Khan Academy.
The idea is as simple as it is powerful. Light rays, or rather waves, move towards a point, and for that they travel a different distance according to their start position.
The difference between two distances determine whether the waves reinforce or negate each other. If the difference is one wave length then we have constructive interference, and by one half-wave length, destructive interference, with all gradations in between.

2) There is something peculiar about light waves. Unlike water waves whose wavelength play no role in the crossing of a split, as long as the split is high enough, for light waves the height of the split is apparently essential.
The wave length is defined as the distance between two peaks two troughs.
Imagine now that the wave has to go through a split as high as the amplitude of the wave, that is the height of the wave. The only obstacle to the wave will be formed by the width of the split since its height is more than sufficient.
But the width of the wave has, as far as I can see, no relationship with its wavelength.
For two waves to go at the same time through a split they would have to have a width each at most half that of the split.
I have not found any indication that the width of the wave played any role in constructive or destructive interference.

3) Something else. Water waves go up and down, but that has nothing to do with any kind of interference per se. It is a simple matter of gravity. Whatever goes up must come down.
About two waves colliding with each other. I can certainly imagine that the water will go higher than any of the waves through the collision, just like flying debris when two cars collide, but that's it.
The whole, mathematical concept of wave is based on the dichotomy peak and trough whereby the first is a positive factor while the second one is negative.
But a trough, at least as far as water waves are concerned, is, once again, the result of the water coming back down. There is not somehow a movement opposite to the the one creating the peaks. In fact, all the energy goes into creating those peaks, the troughs being more of a secondary phenomenon.

The mathematical picture of waves may have its uses as far as calculations are concerned, but it certainly does not give a realistic image of reality.

4) According to the theory, different points, or different waves, go to the same location. Transposed to image formation it would seem that from every point on an object rays are propagated to all points of the image.
Each point of the image is therefore the final and random result of the combination of an infinite number of rays. Statistically speaking, each image should contain as many cases of constructive as destructive interference, especially if it is a monochromatic image. A red object could therefore never look entirely red.

Multiple Pinhole Cameras

If you google this expression, or search it on Youtube, you will find and see many examples of such an original device. I would say that a multiple split grating is something like that. It creates multiple images of the original scene, and that is what we see when we shine a laser beam to such a grating. Through every split a small image of the laser.

Thank you for your advice.

Well, I suppose we have come to what really separates us. Different metaphysical models. See, I do not believe that photons, whatever they are, go on indefinitely. I think it is just a very convenient thing to postulate. It might of course be true, still I prefer the following test which I presented in the other discussion. The one of two observers, one near earth, and the other on Mars, and how they could communicate with each other through telescopes.
Just to avoid any more misunderstandings: sending light or radio signals would happen at a speed lower or at the most equal to the speed of light.

I thank you for your patience and explanations, but I am afraid that we are just like two religious people with a different faith. However much we learn about the other faith, we still prefer our own.

There is hope though, my faith can easily be declared false, and for that the simple test I described is more than sufficient.

I wonder, what kind of test could possibly prove Quantum Physics wrong?


https://thephilosophyforum.com/discussion/comment/109157

While it's in wave or "photon" form there is no way to describe it as physical. It's a very mysterious thing we sometimes call a "particle-wave". — VagabondSpectre

We seem to have left the realm of Physics altogether.

the answer to your question is that individual photons will keep traveling until they encounter some obstacle or are absorbed by something — VagabondSpectre

I will ignore my mistake for now, and plod further. This is a moment of great mystery for me, photons that go on indefinitely unless they are stopped.
I also have great difficulties with the Maxwellian model of electric field creating or calling up a magnetic field, which in turn...
Both these phenomena reek of pepertuum mobile. Don't you think?

That is the explanation I expected. There are some things which I would like you to explain to me. I know it sounds rather simple, but we are trying to determine where our views diverge, and I hope this will help

The electric torch is shining forward, that is the direction of the beam. When the photons coming out of the torch hit the air particles light is produced that is reflected in all directions. My first question, and let us take it one step at a time, is: how far is the light reflected off the particles?

I meant simply an electric torch to light the way through the dark wood.

Each photon in the beam has it's own mass and it's own direction, although in such a beam all their individual directions happens to be the same or almost exactly the same. — VagabondSpectre

You are walking with a friend at night through a wood, she is holding a torch and you follow her a little from behind. She is directing the torch forward, in front of both of you. How come you see the torch?
edit: I mean the beam coming out of the torch.

4) In a beam, each photon has it's own electromagnetic field and it's own direction. The energy required to create and send them on their way must be expended when they are originally created (from a bulb, a star, etc...). The only "infinite movement" I can think of is newtons Idea that an object in motion stays in motion unless acted upon by an outside force. If photons could duplicate and diverge without losing energy then energy conservation laws would be broken (energy will have been created from nothing), which is impossible. — VagabondSpectre

I should have used the term wave instead of beam. After all, a beam is something we perceive, but the wave is what is supposed to explain the mechanics involved.
If I understand you correctly, each time we shine a light, we are in fact, as it were, using a bulb, and not a spotlight, as far as photons are concerned, since every photon has its own direction?

I will make another effort, but this time I will refrain from any controversial claim and simply express what I understood from the objections.
1) photons are in themselves invisible, they need to hit matter to create light.
2) When we are looking at a beam that is directed away from us, even if it is a collimated beam, photons are still propagated in all directions, and when they hit our eyes, we can see the beam, even if there is no visible line from the beam to us. That also explains why we can see someone in a bright place even if we are standing in complete darkness.

Here is what I understand of light in very general terms.
3) The Huygens principle states that everything goes in the same, forward direction, because each point is in itself a wave that drives the beam forward. On the sides, wavelets do the same thing, with a minimum loss of energy to lateral movements, contributing to the forward movement.
4) Maxwell states more or less the same thing, but the lateral movements have become magnetic and electric fields that stand perpendicular to the direction of the beam, one creating the other, producing an infinite movement.

Did I get it right?

it has nothing to do with Romers experiments or contradicting the finite speed of light. — VagabondSpectre

I've had it with you. I am not responding to anymore of your posts. You are just too dishonest. Read again what I said about the speed of light. End of discussion

The fact that we see a light beam that is directed away from us , should be a hint that we need something else but photons to explain vision. Unless you take the Maxwellian model and believe that when we are looking at a beam, say shining horizontally in front of us, we somehow perceive the magnetic and electric fields it is producing. After all, a collimated beam, like a laser beam, is not supposed to propagate any photons sideways. The fact that the beam hits dust particles which make it visible would of course explain the creation of new photons. But we do not see lines of light reaching out to us from the beam. We only see the beam itself.

It is funny that suddenly the number of photons has become insurmountable, when all scientific experiments concerning photons, among those the photoelectric effect, are aimed at controlling the number of photons emitted and received. I admit not being a scientist and I am sure I would get all kind of details wrong, but when I hear somebody as Richard Feynman speaking of a minimum of 5 photons to get a visual impression, and I hear your objections, then I am ready to take whatever figure will suit you. Just tell me which, approximate, minimum number of photons is necessary for a visual impression by one individual, and then explain to me then how so many people can get the same visual impression at the same time.

There is no such thing as photon multiplication. A single candle emits easily over a trillion photons per second. A single photon cannot magically duplicate itself. This would break the laws of thermodynamics — VagabondSpectre

That seems to me to be a hard truth, and I couldn't have said it better myself. So, if photons do not multiply, what are all the people seeing? You want to stick to the principle that photons make vision possible, then you must be ready to believe in miraculous photon multiplication.

You are now being dishonest. A handful of photons is not a scientific term because the post is not a scientific formula but expressing a concept. Take the minimum number of photons that would create a visual impression of any kind and ask yourself how many people would be able to see it at the same time. That is what the miraculous multiplication of photons is all about. It expresses the fact that, despite all your valiant efforts, you cannot explain vision by photons entering our eyes. At least, all your waving with pretty pictures did not convince me one bit.

The problem with such a picture is that even those weak photons are visible from all directions.
Allow me this link to something I wrote almost a year ago on the same subject.
https://philpapers.org/post/22794

The point is that however much light falls on you, it just never seems to be enough to make me visible to you, while you remain visible to me however weak the light becomes. To the point where maybe I will not be able to see you anymore, but still be able to see the light (figuratively speaking). — Hachem

This is of course not entirely correct. Within the same distance I will become visible to you at some point if the intensity of the light is raised high enough. I am assuming a limit to the maximum intensity of light reaching you so that I can still remain invisible. Then we must explain how I can remain invisible in such conditions.

The point is that however much light falls on you, it just never seems to be enough to make me visible to you, while you remain visible to me however weak the light becomes. To the point where maybe I will not be able to see you anymore, but still be able to see the light (figuratively speaking).

You are a real live textbook. So, let me take advantage of it. You reflect enough light back to me that I can see you, but not enough that you can see me. But my eyes could be anywhere. Light that enters my eyes could just as easily fall on any place of my face, or my whole body. And still, you cannot see me, while I would still be able to see you if the light illuminating you would become so weak as to only allow your silhouette to be visible.
Is that what you are saying?

very nice drawings. That is why it took you so long to answer.
The distinction between visible and invisible light is a nice touch. But tell me, when I am looking at you from my dark place, what is reaching my eyes, visible, or invisible light? After all, I am seeing you with my naked eyes, right?

I am glad you are back, let me understand it straight. If I am standing in darkness while you are standing somewhere illuminated, I cannot see you because you cannot see me?

Why is everybody so afraid?

I find it really curious that some issues are systematically ignored when it comes to the theory of light, while at the same time people try to prove me wrong at all costs, even to the point of making me sound ridiculous.

My challenge is very simple:
How come we can see illuminated objects while we are in a completely dark corner where no light reaches us?

If you are unable to answer this question, I cannot take your defense of the established theory of light seriously.

Please prove me wrong! It would make things much easier for me too!

can't win'em all
edit: I would like to thank you though for the opportunity you offered me to clarify some points. You did not make me change my mind, as I did not make you change yours. But that is is the risk and also the benefit of an open discussion.

I am afraid we cannot convince each other.

Again, differences of a second or two would have negligible impact on a demonstration involving minutes. Issues of resolution or parallax would not result in such large delays. — Banno

What you do not seem to accept is that those differences are based on observations. In other words on the fact that observers (or devices) are able to distinguish one object from another. And that in itself depends on distance and resolution, and yes, even parallax.
Your whole argumentation, as was Romer's, is to consider the fact of observation as beyond any discussion. Once you reject this premise the whole argumentation falls in the water.

So it is not at all " like looking at a large object slowly being drawn behind a curtain"; it is instantaneous. — Banno

I find it curious that you do not see the contradiction. Don't you find it strange that one moment Io is there and the other it is not? Isn't that what a snapshot is?

Simulations are very often, as in this case a pedagogical instrument.
Once again, I do not doubt that the speed of light is finite, even though I doubt that light, visible light, travels through space. I consider light as a local phenomenon caused by something which I will call, because I do not have any better alternative, electromagnetic waves, that probably travel through space.
I therefore believe that we see illuminated objects there where they are, and not because their light travels to us, which I find very improbable. We would have to explain how light turns visible, then invisible, and again visible. I still have to see convincing arguments for that which do not rely on my faith in science (which by the way remains strong).

It is in fact quite simple. If you see it happening, then it is not a matter of "snapshot". Let us say you are looking at Jupiter and you see the moon disappearing or appearing. In this case, it would be like looking at a large object slowly being drawn behind a curtain, or from behind a curtain. No snapshots involved. If that is more or less what you see then I can only say that you are completely right.
For Romer, the situation was different, the differences between one observation and the other where probably more snapshot like. One moment Jupiter was alone, the other, there was a moon beside it.
Like when you are looking at somebody approaching you and you suddenly recognize the person. It would be very difficult to pinpoint a moment where that happened. And that is made even more difficult when large distances are involved. I would certainly like to avoid the resolution-parallax discussion again, what matters is that it takes longer for two objects which are very far away to appear as two objects, and not as one.
That is why I consider his conclusion that the speed of light is involved not as irrefutable.
Just as for Bradley, nobody is really interested in the correctness of the argumentation, it would be considered more like a historical curiosity.
I have a vested interest in showing that the wave theory of light is not as impregnable as one thinks, that is why I took time to analyze old texts and experiments like that of Romer, Bradley and others.
The images I have taken are also completely on topic. They show that another interpretation is possible of light phenomena that have always been considered as strong proofs for the correctness of the wave theory.

I have no interest in explaining my position over and over again anytime someone new comes in.

I am sorry. I am out of patience. Nothing personal.

How are lasers made?

Look at this image and tell me what it reminds you of.
https://youtu.be/qkQo6gig3tQ?t=55

Destructive Interference?

Look at the image on the screen that the M.I.T professor uses as a proof of destructive interference.
https://youtu.be/RRi4dv9KgCg?t=94

His argument is that by pushing on the plate he changes the distances between the screen and the dark and bright rings of the image, making them alternate. Those black rings are according to him the result of destructive interference. The problem is that in my experiments bright rings did not suddenly black rings when I changed the position of the laser. So, what the professor might be showing is simply two alternate images in time and space that give the impression that black has turned red, and vice versa.

Yes, that is right. His argument is, as far as I can see, wrong. That does not mean that he is wrong about the idea of light speed being finite. I hope you can make the distinction between both positions.

Here is another example of bad argumentation that has always been considered valid while it is wrong logically.
https://philpapers.org/post/20762
https://philpapers.org/post/20890
https://philpapers.org/post/21002

I expect people to read carefully before they comment. And you are not doing that.

Why is everybody so keen in making me say that the speed of light is infinite? Did you even read what I wrote? It is about perception times!

I am afraid you are wrong. Romer's calculations were based on the average of observations made over 10 years! So it was a matter or seconds, or even less!

edit: it always looks instantaneous. One moment Io is indistinguishable from Jupiter, the next it is. That is the whole point in fact.

Here is an intermediary phase. This picture has been taken with 1/500s


And this one with 1/2000s.




edit: If you take a thin band of the central spot and the different rings, you will see that it is the same result as the one shown by two-split experiments and other images used to prove the wave theory of light.
edit2 The large oblique beam is I think the result of back and forth reflections of the prism that directs the image to the viewer. But I am not really sure.

Faster than the speed of light?

My theory, or rather my raw intuition, will be easily falsifiable. Imagine two observers, one near Earth, the other on Mars, looking at each other through powerful telescopes.

They can see when their colleague millions of kilometers away raises a board with a number on it. They must then raise a board, or type a number which shows up on an electronic board, a number that is one higher than the number they saw, or whatever formula they have agreed upon.

They will immediately be able to determine how fast the information has reached the other side. My prediction is that they will see it immediately, even though any other form of communication between Earth and Mars will be much slower than the speed of light.

edit: They could even play chess, like the characters in one of the sequels of Resident Evil. But they will have to acknowledge which move they have received from their opponent as soon as they see it.

3. We disagree on the differences and similarities between resolution and parallax, but we agree on the fact that resolution is involved when looking at the moons of Jupiter to determine the exact moment of their eclipse or reappearance. Maybe we should concentrate on that.

2: It means that there is a continuous flow of photons, and the "snap-shot" effect you're trying to describe is a mere consequence of us actually taking snap-shots. No such effect has been demonstrated to exist or to be the cause for the variations in eclipse duration of Jupiter's moon. — VagabondSpectre

You interpret "snap shot" as meaning a discontinuous flow of photons. I agree with you that it is highly unlikely. But then I do not think we see objects because of what had been called photons.

A central tenant of light theory is a straight beam carried by waves, and supported at the sides by wavelets. The Huygens Principle, fine tuned by Young, Fresnel, Maxwell and others is supposed to explain how light can go on indefinitely, and also how we see objects.

A simple refutation of the Huygens Principle I have dealt with in this discussion and the other one mentioned is the fact that we can see objects even when no visible light rays are entering our eyes.

We can see them from a completely dark corner, and therefore also from aside. I do not know how that is possible and what creates this "lateral" perception, but the Huygens Principle and the theory of light cannot account for it.

Maybe other electromagnetic waves than visible light are making it for us possible to see objects even when there is no light ray reaching our eyes. But then, if we can see objects whose light is directed away from us, the so-called wavelets that are supposed to sustain the main wave must use energy in all the other directions, weakening the main wave.

In fact, it is probably what is happening when we consider the fact that visible light weakens with distance until it disappears from sight altogether.

I have given many examples of this kind and I did not get any answer from all the objectors. But I have not lost hope yet.