Dalo

Why I am a determinist
Descartes had his treacherous demon that tried to confuse him and lead him astray, and the only certainty Descartes then had was his cogito. Even confusion presupposes thought.

Modern physics has taken over the role of the evil demon and confusion is queen (or king?) again. With this huge difference: thought does not help anymore to create a rational world. You may think what you want, Reality does not seem to care.

Atoms and photons go through any slit they feel like going through and zombie cats rule.

There are many philosophical and metaphysical arguments in favor of determinism. I will give you only one.

Non-deterministic models presuppose that matter behaves randomly and that in turn presupposes a minimal intelligence of matter. Before reacting an element of matter would have to choose which line of action it should follow. Should it act like a wave, or like a particle? And how would it choose?
If it does not need to choose, then we are still within a deterministic model even if different courses of action are available.
A photon or electron acts as a wave in configuration A, and as a particle in configuration B. We may find it strange or even mystifying, but in the end we still have the same Principe of one cause to one effect.

1 minute ago, Strange said:

And if you block all the rays, then you can't see the light source at all. This is why you can't see then sun when you are down a coal mine. Or at night.

wrong arguments since in those cases the sun is not in the line of sight as the lamps would be.

My point is: when beams are blocked, we get to see the light source, here the sun, in my experiment the (laser) lamps. But please let's not restart the discussion. The authenticity of my previous picture of the sun had raised doubts which I could not take away, not having noted the conditions under which it was taken. So, today, I took another picture of the sun with the same filter.

1 minute ago, swansont said:

When you put on a pair of sunglasses, things don't disappear.

I am sad to say that I believe you.

Taken in the afternoon between 3 and 4 with filter cap normally used with a telescope to observe the sun. As you can see, the sky is completely dark, all the sun rays having been absorbed, leaving only the sun itself.

29 minutes ago, Strange said:

OK. Maybe we are getting somewhere now. This relates to the difference between your use of 5 lasers and photographing a general scene.

So you are comparing the loss of the background with the addition of the filter, to the loss of some of the lasers? 

This is not a valid comparison.

In the case of the Sun you have one bright source surrounded by an illuminated sky. Both the Sun and the sky radiate light in all directions. (Unlike the lasers.) The Sun is many times brighter than the sky (a few million times brighter, I think). This means that if you put a filter in the way, the sky will rapidly drop below the level of detectability, while the Sun is still visible. (This would be equally true if you achieved the same exposure by using a very short exposure time and a very narrow aperture - it is not related to the filter itself, just the relative brightness of the Sun and the background.)

In the case of your 5 lasers, there is almost no other source (I am assuming we are doing the experiment in the dark, as in the video you posted). Therefore the only beams are the (unidirectional) beams from each laser, creating the images of those sources. The brightness of these will all be changed equally by the filter. So there is nothing that will disappear or appear. It s just the brightness of the image that will change.

This is more of an analogy. And the difference is what makes the experiment meaningful in my eyes.

By reducing the intensity of the light, the laser lamp (the light source) itself becomes visible, just like the sun through a filter. Remember that when I used the term mini suns for the first time, I assumed that they propagated light in only one direction. This is I think the fifth or sixth time that you, and others, have tried to remind me that light is propagated in all directions, which is an undeniable fact.

That is why I am using unidirectional lasers (or lamp with slits).

Please stop repeating the same objections over and over again. It looked like my setup was finally clear to you. It is obvious that you do not agree with my prediction. You think an experiment is superfluous. What more could you possibly say that would make me change my mind?

I will tell you, hoping that it will all save us time and energy, and protect us from frustration:

only an experiment that would prove me wrong will convince me. 

There is no theory that, at least in principle, could not be falsified by an empirical experiment, how trivial it may seem.

30 minutes ago, Strange said:

Just in case (and feel free to be offended by this) ... you do realise that the reason you can see the beams from the lasers in the video you posted is because they are shining on (and reflected from) the white surface that the experiment is being done on? You can't see laser beams in the air. But you knew that, of course...

yes I did. But what I mean goes beyond that: the beams are not projected on the screen anymore. Just like in the case of the picture of the sun with a filter. The sky is dark, and only the sun is visible.

27 minutes ago, Klaynos said:

Are you suggesting that the filter completely removed the lasers so they are not dominating the response of the sensor and then you are illuminating the scene with some other light (e.g. room lights) and can image the front of the laser sources?

No, when you use a gray filter the beams are mostly absorbed and are not visible anymore. Just like when you take a picture of the sun using a so-called sun-filter

4 minutes ago, Strange said:

No. Projecting five parallel laser beams through the system is NOT the same as "any other scene". 

when using the filter the beams are not visible anymore, only the light sources. In this sense, it is just like any other scene.

Your judgment expresses your confidence in the theory, and there is nothing wrong with that. That does not mean that an empirical confirmation would be superfluous.

19 minutes ago, Strange said:

Can you explain why you think adding the filter might make the blocked lights visible?

I already did, but I will say it again.

You have to imagine that the filter is being used, and that the diaphragm is completely open. In such a situation it is to be expected that all five light sources will be visible on the screen. Such a situation is comparable to any other scene being projected through a lens on a screen. Closing or opening the aperture should have no effect on the field of view, and all the five sources will remain visible whatever the aperture.

In other words, closing the aperture will have an effect on the number of beams passing through the aperture, but not on the number of light sources projected on the screen.

It is of course only an abstract prediction that must be confirmed, or infirmed, empirically.

I do not have a full fledged theory to justify my prediction, but I would like to know first what its value is.

When the diaphragm is completely open, five beams pass through the aperture, three when it is closed.

My prediction is, when the (neutral) filter is used, five light sources will be projected on the screen, even if the aperture would only let three beams through.

I am not a talented artist, and the way the beams are refracted is certainly not realistic.

2 minutes ago, Strange said:

You appear to have changed the question. From field of view to some nonsense about filters.

Not true. I cannot help it if you are unable to read texts without being blinded by your prejudices.

35 minutes ago, Strange said:

Although, as always, Dalo has changed what he is "really" interested in since the original question. Just a symptom of his chaotic thinking or a deliberate attempt to derail his own threads? I don't know.

Indeed. I have no idea if Dalo either understand or cares about that.

not true. I kept the same model the whole thread. Sometimes I used analogies to clarify what I meant. But if you read my posts carefully you will see that I remained consistent all along.

Concerning the 5 laser beams, they are essential to the experiment. 

Just now, Strange said:

I am assuming you mean a clear, neutral, photographic quality filter that just reduces the intensity but doesn't, for example, change the direction of the light.

of course.

It is now clear where we both stand. I think a further theoretical discussion will not bring up any new facts or make us change our respective mind.

7 minutes ago, swansont said:

Either you close (or move) the diaphragm, or you add a filter. Not both.

I do not see why.

1) The diaphragm must keep the same position for the whole experiment.

2) the aperture, opening of the diaphragm can be varied.

3) The filter is applied to the source of light, before they enter the lens.

There is only one layout, maybe I should have clearly indicated that the one with the diaphragm place on the focal length is completely uninteresting.

The diaphragm will therefore have to be at a position where all five beams can pass when it is completely open, and only three beams can pass when it is close.

edit: if you still think that a filter should have no effect on the number of sources projected on the screen, with the condition as stated concerning the position of the filter (before the beams enter the lens), then you prediction is exactly the opposite of mine. You may be already convinced that you are right, I would like to see it confirmed by an experiment.

14 minutes ago, Strange said:

Do you have any preference for the position of the diaphragm?

Let's stick with the simplest, and the most realistic: keeping it at the focal point.

Here it is with the diaphragm fully open:

And, as expected, we can see all 5 light sources on the film/sensor.

 

And now here it is with the diaphragm closed down.

And, not surprisingly, we can still see all 5 light sources on the film/sensor.

Are you happy with that? 

(No one is going to do the experiment for you, so this will have to do.)

OK. You like the idea that some beams that should be blocked. Lets move the diaphragm adjacent to the lens:

Here it is with the diaphragm fully open:

As expected, we can see all 5 light sources on the film/sensor.

 

And now here it is with the diaphragm closed down:

Now we can see just the 3 light sources that are not blocked (shadowed) by the diaphragm.

So, is there anything else to say?

Now you start with the second phase of the experiment. The dimming of the beams with a filter or otherwise.

It is obvious that when the diaphragm is completely open, we will see projected on the screen five spots representing the five sources.

The question now is: will we still see five sources with the diaphragm at the same position, the one in which it blocked two beams, or only three sources projected on the screen?

4 hours ago, Strange said:

Can you confirm if zero, one, or more of the following illustrate the experiment you wish to perform. And if none, why not.

From up to down.

1) The first drawing should have a diaphragm as well, open all the way. That would be the initial situation.You could use the third drawing, but then the opening is smaller than the opening of the second drawing where only 3 beams pass through. That would be confusing.

2) The second drawing would correctly show three bright spots on the screen, representing the three beams which have gone through the diaphragm.

3) The third drawing needs to make clear that the lines do not represent the beams (which have been dimmed), but their sources, which I called lamps or mini suns. The  five projections on the screen would represent the fact that even though the position and size of the aperture is equal to the previous drawing, where only three beams passed, we can nevertheless see five spots representing the sources.

It is therefore imperative that the same position of the diaphragm be used for all situations, the only difference being the size of the aperture and the number of beams going through it.

I hope I will not need to confirm once again that a change of aperture does not affect the field of view, but only the number of beams that can pass through the aperture. That is what makes this experiment interesting in my eyes: three beams, five lamps/mini suns.

I do not know if the result will be as I predict, that is why I hope to see it done one day, by me, or by somebody else.

1 minute ago, swansont said:

Then this is trivial. Parallel beams hitting a lens all go through the focal point. Closing down the aperture has no effect on the number of beams.

Do you even read what has been written, or do you just react to isolated sentences?

9 minutes ago, Strange said:

Then why introduce "suns" and filters?

This shows your inability to read posts carefully instead of reacting to your own ideas.

Filters are needed to reduce the intensity of the beams and show the "mini suns" as objects that can be reflected on a screen.

I agree completely that aperture does not change field of view... except in the case of beams. That you ignore this shows how little you have understood my proposal. Denigrating it won't change this fact.

If you think it is pathetic to wait for somebody to perform the experiment instead of doing it myself, why don't you do it yourself and prove me wrong once and for all. Put your money where your mouth is.

I know I do not have the proper gear to do the experiment in a professional way. Maybe you do, or do not care? After all, it is only $10, right?

26 minutes ago, swansont said:

Again: claimed, but not demonstrated.

agreed. That is why I proposed the experiment.

28 minutes ago, swansont said:

Light does not follow just one path. "another path than the beam" makes no sense.

Light hits an object and light reflects off of it at many angles. All of the points on the lens are hit with it, and these form an image. There is no "beam" in this situation. Blocking part of the lens makes it dimmer but has no effect on the formation of the image.

You are changing the premises. We are talking about uni-directional beams, like lasers.

2 hours ago, Strange said:

And don't complain about me introducing omnidirectionallity; you did that when you moved the goal posts from lasers to suns.

11 hours ago, Dalo said:

Imagine 5 small suns which happen to shine in only one direction.

1 hour ago, Strange said:

What is the difference between seeing the sun and seeing the light from it?

I am sure you know that you cannot observe the sun directly.

1 hour ago, Strange said:

Putting a filter in the way will just reduce the amount of light. It won't change the path of the rays and hence it won't change what is visible.

When you take a picture with a camera the diaphragm is wide open. Imagine that when you preset  the diaphragm at, say, f/8, two of the five beams are blocked. Before pressing the button, the image is bright because all beams are let through.

Keeping the camera at the same position, you now use a gray filter in front of the beams. Even through the open diaphragm, the scene is much darker. But you can now see all five mini suns.

Since the field of view must remain unchanged, you should be able to see all five mini suns, whatever the aperture.

But f/8 lets only three beams through when no filter is used.

According to your rule, using a filter would change nothing except the amount of light (and therefore the shutter time). That would mean that we should see only three mini sun.

Both possibilities are contradictory.

7 minutes ago, Strange said:

YOU CAN'T SEE THEM. See the diagrams I provided previously.

You can't see the lasers that are blocked by the diaphragm. As shown in the diagrams I provided.

By the way, when the beams are blocked by the diaphragm, you can't see them. I provided a diagram to show why.

No, you can't see the beams that are blocked. That seems pretty obvious.

Imagine 5 small suns which happen to shine in only one direction. Two are blocked by the diaphragm. Only three spots will be visible on the screen. So far I think that we agree with each other.

Let us now reduce the intensity of the beams by dimming or by using a gray filter. It would make the suns visible while before all we could see were the beams of light.

The question now is: imagine that we are still using the same setup, with the diaphragm at the same position as before, where it let 3 beams through and blocked 2.

How many mini suns will be projected on the screen?

If it is 3, then we have no discrepancy with the number of beams.

If it is 5, then we do have a discrepancy.

1 hour ago, Strange said:

It affects the case of 5 laser beams parallel to one another.

It doesn't affect the case of light coming omnidirectionally from a normal photographic scene, and therefore it doesn't change the field of view.

Yes and yes. What is not explained, and I am repeating myself, is, considering only the first case (of 5 laser beams parallel to one another) how it is possible that even when two beams are blocked, we still can see all 5 lamps from which they originate. Somehow they must emanate rays that go through the diaphragm, while they are at the same time time the sources of the beams that are blocked by the same diaphragm.

If that is the case, images of illuminated objects are not projected the same way as images of beams, because if that were the case, we would, under the same conditions, be able to see the same number of beams and lamps.

What would make perfect sense is that when beams are blocked, the lamps from which they originate should remain invisible even if we reduce the intensity of the beams. After all, what we are seeing is supposed to be light reflected from the lamps whose beams are blocked.

I still hope somebody will perform the experiment and make a video of it.

edit: I don't know who downvoted me, and I really do not care. It is obviously someone who has no idea what the meaning of the experiment is. I think that Strange understands it perfectly, but is victim of what is called cognitive dissonance. That is is why he tries so very hard to make it sound like I am the one who is unclear.

1 minute ago, Strange said:

What do you mean by "the one case" and "the other case"? Do you just mean "aperture open" and "aperture closed"? If so, my diagram explains why the light from the outer lasers gets blocked.

Again, not sure what you mean by "one way" and "the other".

It affects the case of 5 laser beams parallel to one another.

It doesn't affect the case of light coming omnidirectionally from a normal photographic scene, and therefore it doesn't change the field of view.

I have tried to explain the reasons for this. I'm not sure why the explanation isn't satisfactory.

What is your assumption? And what is the discrepancy?

Your posts are so vague it is very hard to understand exactly what conditions you are talking about, what you think will be the result and why you think there is a problem.

 

goodbye.

You are playing dumb, and it certainly does not suit you.

In one case the image contains 5 elements when the aperture is completely open, in the other case it contains only three after the aperture has been closed.

So, even if you want to be a purist, you will have to admit that closing the diaphragm affects what comes through the lens in one way, but not in the other.

Also, if my assumption is correct, then we still do not have an explanation for this discrepancy.

You may of course withdraw from the discussion at any time.