Physics theories and experiments by

David Chalmers

The well known physicist Richard Feynman was fascinated by Young's double-slit experiment, often stating that the experimental results never could be explained in terms of any one or more understandable physical principles.

However if you click here you will receive an executable file (PC format) that proves Feynman wrong. The program represents a simple physical phenomenon. Exactly the same algorithms apply whether one or two slits are open, so the same physical principles apply in both cases. As will be seen, 1 slit open results in a no interference pattern, whilst 2 slits open results in a standard interference pattern, both just as in the actual experiment.

The simple physical phenomena used in this demonstration is not explained here, as its details are irrelevant to Feynman's argument, that no physical phenomena can be conceived that produces the same basic result as the actual 2-slit experiment. Such phenomena have been made up as the demonstration proves.

This one demonstration proves that the experiment can be explained in simple terms and has many ramifications. In particular, we can state now without reservation that quantum Mechanics needs at least a certain amount of reforming.

The experiments and demonstrations presented here show that both wave theory and quantum mechanics need revision.

Wave Theory

The intensity of a light beam measures the intensity of the energy of the beam. The amplitude of a beam is calculated from knowledge of the intensity, but amplitude is not a real entity. It is just a convenient mathematical device. If two beams have the same polarisation, another mathematical concept, then if the beams are mixed, the amplitudes have to be added, then the modulus obtained to find the new intensity of the combined beam. On the other hand, if the beams are orthogonally polarised, the intensities have to be just added together. This is all standard theory and not that of the site owner. After studying the experiments and demonstrations on this site, it will be obvious that observed intensity is NOT the same as wave or photon intensity.

Quantum Mechanics

Again there is a concept called Amplitude also known by several other names, which is treated in much the same way as above, but when the modulus is formed, it is said to represent the probability of finding a photon at a particular point in space. The photon probability is equivalent to the intensity, and as stated above is shown here to be proportional to the photon intensity.


Object of experiment. To show that in the interference pattern displayed on a screen, there is a smooth distribution of incident photons and energy. For the first and most important part of the experiment, only three pieces of equipment are required, and these usually can be found in any school physics laboratory or simply obtained elsewhere.
A low power laser, e.g. helium-neon, is set up with its beam impinging on a large screen about 3 to 4 metres away. The edge of a brand new razor blade, with the edge vertical, is introduced into the laser beam near it origin. It is set so that about two fifths of the beam is blocked. The arrangement is shown in Fig 1 below.

Light that passes very close to the edge of the blade is diffracted as shown in the figure. I prefer to use the word deflected since 'diffracted' gives the impression that the exact mechanism that causes the light to be deflected is understood - it is not understood. It is vital in the further understanding of the experiment, to appreciate that the rest of the beam, which is not blocked, passes the razor edge too far away to be affected or deflected by the edge.
On the screen, the undeflected light just produces a bright spot, whilst the light that has been deflected produces a continuous beam of light, extending equally on both sides of the bright spot.

A second razor blade edge is now introduced into the part of the laser beam about two inches further along the laser beam. It is introduced however, at the other side of the beam, but again so that it blocks about two fifths of the original beam. Thus, there remains one fifth of the beam that remains unaffected and undeflected. The second edge, being identical to the first edge has exactly the same light and energy deflecting characteristics. Its affect is not influenced by the first edge, and the first edge is unaffected by the second edge. This all follows from the fact that there is an undeflected one fifth of the original beam that passes both edges at the same distance - too far away from the edges to be affected. Note that the body of the second razor blade will block half the deflected light from the first edge. However, the second edge must cause the same distribution of light and energy on the screen as the first edge. When we examine the composite image on the screen, we see that at part A where deflected light arrives from only the second edge, the anticipated continuous line of light is seen. When we examine at the point where light arrives from both the edges (part B), a typical interference pattern is produced due to light from the two razor edges, as shown in Fig. 2.

We know that both edges must have the same even distribution of light and energy on the screen at B, therefore there must be the same energy distribution at the bright fringes as at the dark fringes. At first thought this seems impossible, but we must remember that experimental results must always take precedence over theories, no matter how well and how long these theories have existed and been believed by multitudes of university students. In the two remaining figures, methods are shown that confirm that the presence of any one edge has no affect on the other. No detailed explanations of the figures are made, since the methodology will be self-evident to anyone familiar with optical laboratory procedures.

Conclusions

Although standard theories assert that there is little light nor energy in the dark fringes, this experiment shows that is not so, and there is the same amount of energy incident at both dark and bright fringe areas. There is however, a well-known standard "proof" that almost all the energy is in the bright fringes and hardly any in the dark areas, but it is a 'proof' dependent on the standard theories. Since here these theories are in question, they cannot be cited against the experimental results, otherwise we would have a circular, and therefore meaningless, argument.

Here I propose no detailed explanation of the observed effect, other than to say I use my personal explanation for all the experiments, and also in the demonstration of Young's two-slit experiment that you may download if you have not already done so. I call it the Accumulator Effect. Since both wave theory and quantum theory contain this error, regarding the distribution of photons in an interference pattern, it will be necessary to modify them if they are to continue to be taught in schools and universities. First, it will be necessary to overcome the prejudice and narrow-mindedness. Secondly the stress and fear associated with the career prospects of all teachers of these flawed theories will have to be overcome.

Object of experiment. To show that a beam of photons can be invisible and therefore almost undetectable.

This experiment is a modified form of Michelson's interferometer. It has two added parts. First, an additional mirror (mirror 3 in the diagram) is added to reflect back into the interferometer the light that usually forms the main output of the interferometer. The second addition is that of a second beam-splitter, placed between the laser's output and the interferometer proper. This second beam-splitter directs half the light from the single output that is heading back towards the laser, from the interferometer onto a screen. Its function is to provide a means of conveniently monitoring the interferometer's light output. A lens widens the image on the screen and again is present just for convenience. All the mirrors of the interferometer are set-up to be perfectly aligned. The means of ensuring this alignment are obvious to those familiar with working with interferometers, so no explanation here. The actual experiment is now done by moving one or more of the mirrors, 1 through 3, so that the light seen on the screen is a minimum. Of course, these adjustments are carried out with aid of specialised manipulators. Given that no matter how precisely the optical components are manufactured, there will be some imperfection in the image, so that zero light on the screen will be unlikely, nevertheless the minimum will normally be very close to zero. The question is; What has become of all the light and associated energy which enters the interferometer?

Interpretation: - Two professors have analysed this result using wave theory and their conclusions are illuminating. First, they add all the components of light that are reflected back towards the laser and screen. They agree that for certain positions of the three mirrors, these components sum to zero in accord with the experimental result. However when asked where the light and energy has gone, the answer is given that it has been dissipated at the surfaces of the mirrors, because there are multiple reflections occurring. There are however two problems with this "explanation". First, if the light is dissipated in the mirrors, how is it that its components heading towards the laser can be added? How can light that is lost in the three mirrors, also exist on its way towards the screen when it has been dissipated in the mirrors? The second way to show that this interpretation is wrong, is to use mirrors that transmit a very small proportion of the light hitting their surface. This transmitted light need be only 1%, so that the rest, minus losses, is all reflected. This transmitted light can be monitored with light sensitive detectors. The transmitted light is of course a small part of the light in the three arms of the interferometer. When this is done, the total transmitted light is found to be virtually constant whatever the settings of the mirrors. Thus we can set the light intensity on the screen to a maximum or a minimum (zero), and observe that the light intensity in the three arms and therefore the losses in the three arms are the same in both cases. Now when there is a bright light on the screen and the losses are the same as when there is nothing on the screen, it follows that losses cannot account for the disappearing light.

Of course the correct interpretation is simple and easily understood, provided that one dismisses the previous indoctrination that we all have undergone at one time or another. There is nothing wrong with indoctrination provided that we realise it is just that, and that we are prepared to discard it when a better explanation or an original experimental result is available:- as here.

As in the first experiment, we see that it is possible to have a beam of waves/photons that are not visible, but exist.

This experiment shows that the two principal theories of light phenomenon, wave and quantum theories, are flawed and should be recognised as such, so that modified versions can be formulated. To continue teaching theories that are proved by experiment to be wrong is anti-scientific.

It has always been argued that when a change occurs in the intensity of interfering beams, due to the phase relationship between the beams being altered, then a increase in intensity at one point is compensated by an decrease in intensity at another point. In the experiment described below at one point the intensity changes from dark to bright, by .0736, whilst the only other point to change intensity does so by only .0032. Thus the usual assertion is shown wrong and it follows that postulates, theories and mathematical processes based on this wrong belief must be flawed to some extent.

The experimental arrangement is very similar to the well known Michelson Interferometer. However instead of the usual 50/50 beam splitter a thick glass plate is used. Its actual thickness is not important as long as it is thick enough to allow separation of certain of the various reflections. The part of the figure labelled "First reflections" shows how the laser beam is split into three beams when it first encounters the glass plate. A reflection of 4% of the intensity occurs at the front surface of the plate and is absorbed by a optical stop (1) as it is not required in the remaining parts of the experiment. A further 4% approximately is reflected from the internal surface of the plate most of which leaves the plate heading for mirror M1. The remaining 92% of the laser beam leaves the far surface of the plate heading for mirror M2. The part of the figure labelled "Second reflections" shows what happens to the two beams after reflection from M1 and M2. The beam from M1 is reflected twice just as the original beam from the laser was reflected, so that 4% of it is reflected first to a stop and and a second 4% reflected back towards the laser. These intensities are so small that for our purposes they can be neglected. The remaining 92% (of the 4% from M1) leaves the plate heading for the screen. Meanwhile the beam reflected from M2 reflects 4% (of its 92%) towards the screen, coaxial with that from M1. It also passes 92% of 92%, which equals 84.64%, back towards the laser. Thus there are two sets of beams that can interfere constructively or destructively, according to the phase relationship set by the position of M2. The Table in the figure sets out the resultant intensities of the two beams for the two extreme positions of M2. These positions are for maximum and minimum intensity on the screen. It is seen that the variation of intensity of the beam heading towards the laser is only .0032 whilst that on the screen is .0736, a ratio of 1 to 23. Thus moving M2 from one position to the other changes the intensity on the screen from bright to dark, whilst there is no corresponding intensity change in the beam heading towards the laser. Later this can be monitored conveniently by replacing a third stop by a screen, because the light at this point is a simple fraction of that heading back towards the laser. Note that there are some other reflections that have not been mentioned, but they are of very low intensity and more importantly do not give rise to any interference effects. The experiment shows, in a very simple way, that two beams can interfere to give an invisible beam (darkness) without there being any other compensating effect.

Object of experiment To show that at an area corresponding to a dark fringe, the energy and photons that are "invisible", can be re-constructed as a visible image.

Although the apparatus, like that of the other experiments, is simple and easily accessible, it does incorporate one special piece of apparatus - a mirror. This mirror is somewhat unusual in so far as it is specially shaped to correspond with the shape of just one interference fringe. To produce the fringes, a Michelson interferometer, in which the reflection mirrors are very slightly mis-aligned, is used in conjunction with a short focal length lens. The arrangement and the fringe pattern is shown in the diagram.

A screen is used to help set the interference pattern so that about four fringes are produced within a circle of 3 inches diameter. It would be possible to select just one of the fringes, bright or dark, by making an appropriate shaped slit in the screen, but this would have the unfortunate effect of producing, at the same time, a lot of diffracted light, caused by the slit's edges. To overcome this difficulty,the specially shaped mirror is used to select and reflect the fringe to be used by simply placing it just infront of the screen at a dark or bright fringe area. Diffraction effects still occur, but none of the diffracted light is reflected into the path of the remaining optical components, which consist of a set of suitable lenses (3 in my case). These are selected and positioned to produce a much enlarged, in-focus image of the two virtual light sources which give rise to the interference. The images of the two sources should be spaced about 1cm apart and appear on a screen, which can be conveniently observed in subdued lighting conditions during the rest of the experiment.

Experimental method

1) The special mirror is placed exactly where a bright fringe occurs, in front of the screen, and the lens system is adjusted to produce clear images of the two light sources. Now the mirror is moved into a position where previously there is, on the screen, a dark fringe. It is observed that the two images remain substantially the same. This is in contradiction with standard teaching, which insists there is very little energy in the dark fringe area in comparison with that in a bright fringe area.

2) Now the lens system is adjusted to de-focus the images so that they overlap, whereupon the overall brightness of the images is much reduced. If the small mirror is placed to reflect a bright fringe then the overlapping will give a brighter image than when a dark fringe is reflected. It is obvious that the energy passing though the lens system is the same irrespective of whether the images are in or out of focus yet the intensity changes dramatically. Standard theories do not predict or acknowledge this effect.

3) In the final part of the experiment, a small piece of dark card is used to block, in turn, the path of the light within the interferometer which is responsible for one of the light sources. Under this condition there remains only one light source so that no interference can possibly occur. This means that where there was a dark fringe area there now must be an intermediate light intensity. This intensity is uniform over the 3 inch diameter area of the original fringes. Thus at a dark fringe, this area will increase in brightness when any one of the light sources is blocked. It is observed that the only effect on the image screen is that one or other of the two images disappears/reappears. That is, the total image brightness is halved/doubled whilst at the same time the intensity at the selected dark area decreases/increases. Again this could not possibly be anticipated according to standard teaching.

Conclusion:- Each of the three variations of the experiment proves, by demonstration, that just because it is not possible to see light at a particular place, it does not mean that there is no light energy there, and that in at least some situations it is possible to re- transform this hidden energy back into observable light.

The object of the experiment is to show by a simple argument, based on classical wave analysis, that the assertion by Dirac that each photon passes, in some unspecified way, through both / in / and interferes with itself.

The apparatus of the experiment is shown here and could be classed as an Eraser type experiment due to the last polariser. The eraser is applied to the polariser just in front of the screen. A laser supplies the light, and the output beam is plane polarised at 45 degrees by a sheet polariser. The light then enters an arrangement that is basically a / First the light is split by a beamsplitter and later recombined by a second beam splitter. There are two outputs from the second beam splitter but only one is used, the other is incident on a stop and therefore plays no further part in the experiment. One of the two paths has a vertically orientated polariser through which the photons pass, whilst in the other path a horizontal polariser is positioned. The eraser polariser is positioned in the path of the operative output beam oriented at 45 degrees. In both cases photons that pass along the top / must be vertically polarised and therefore cannot at the same time pass through the lower / Without the eraser polariser in posion there would be no interference pattern produced since it is well known that orthogonally polarised beams cannot interfere. However with the eraser polariser in position, set at 45 degrees, the two beams reaching the screen are both the same polarisation and therfore an interference pattern will be produced on the screen.

Analysis

It is impossible that a photon can, in any way, pass along both the top and bottom paths because of its specific polarisation. Therefore each photon passes through only one / yet interference still occurs. The interference is therefore between photons that have passed through opposited / This is in contractiction the the Dirac assertion. This assertion however is at the heart of modern quantum mechanics which therefore must have some modification made to it if it is to be taken seriously in the future.

Below are some of the more frequent reasons given so far as to why some of the experiments are flawed.
Also I give the fundamental reason why these type of arguments are invalid.
1) The experimental results must be wrong because they are not in accord with standard theories.

2) The primary experimental observations are just as would be forecast by a standard theory.

3) The experiments can be explained by the following [ad hoc] theory.

4) Objections based on not having read the explanations of the experiments carefully enough.

5) Sheer prejudice based on long years of indoctrination and an unwillingness to admit being wrong.