As I started wondering about how to distinguish a real from a virtual particle, I came across a theory called QED. I thought the education in India was pretty good, till I heard this name! This theory was developed in 1929, 70 years before something serious about light was thought during my higher schooling! Even though we had chapters on optics and light, to my surprise I had never heard about this theory till now. I don’t know whether my general knowledge is to take the blame or my education, but never the less I came to know about it by the grace of the internet. I bought a book on this theory of physics whose author is a person who has actually contributed a lot to it. He is a physicist himself, by the name Richard P Feynman. The book is titled “QED: The Strange Theory of Light & Matter” and costs around 170 INR.

The theory goes with the title and is very strange, but claims to explain every phenomenon of light and even more. Well that’s what a theory is after all, and is going to stay till we observe a phenomenon that this theory fails to explain, or how else will you be able to disprove it. By the way I forgot to tell you what QED means, it means Quantum Electrodynamics, and people who are familiar with quantum physics would already know that you need to lose your common sense in order to understand any quantum theory. I will not go into the details of the theory, but will mention some points that might be useful in the present context, i.e. to distinguish a real from a virtual particle.

Let me ask you a question before I start off with this theory. Is light a particle or a wave? If your answer is that light has a dual nature and behaves both as a particle and a wave, you are probably some 80 years back in time, which is where I was before I read this book. It’s high time that you change your thoughts now. “LIGHT IS A PARTICLE” and there is no duality associated with it! When I say light, I mean a particular point on the electromagnetic spectrum; a chain of increasing frequency. If light is a particle, what does the frequency associated with it have to do with it? This frequency concept remains intact and gives the energy to the photon, higher the frequency of the photon, higher is its energy. E = h*f. So the energy associated with the photon depends directly on its frequency, unlike the usual way in which the energy or the power associated a wave is dependent on its amplitude, like the AC signal coming to your house. This was the basis of the photo-electric effect; to prove that light is indeed a particle. The frequency associated with the particle is like a stop watch hand or a phasor, the higher the frequency, the faster it completes one circle. If the phasor is stopped at a particular time it points in a particular direction, which is the basis of QED. No, I am going to stop this here, because I am not able to compress the theory more than what is done in the book, and if I continue I will be reproducing the whole book here, which is against the copyright laws! The author has actually described the complete theory in mere100 small pages, so may be you can read it and come back here.

If you have read the book and this article from first, I think there is nothing that I have to write here, because only after reading till page 58 of the book you would know the answer yourselves. Anyway to make this article complete let me put it here. From now on remember that the diagrams contain the whole lens, even though only the boundary rays will be shown. The concept of a magic circle has already sunk.

If QED is going to work, you might now feel that all the different kinds of solutions I was trying to give have been a waste. If we are going to depend on QED for our answers there is absolutely no need for the magic circle in the lens that we were talking about all over this article! The part of the sensor that is of interest to us is the pixel that is in line with the optical axis of the lens. According to QED, objects form images at a point where all the photons have the same direction of the phasor (refer page 58 of the book). Now, if this were to be true, instead of having a magic circle as before, we can now have a magic central sensor. This sensor is going to keep track of the direction of the phasor, don’t ask me how, but let’s assume and see if it solves our problem. The reference direction is obtained by the photon that is traveling on the optical axis (axial photon). If all the photons collected by the central sensor are in the reference direction, you have a perfect focus. This is true only if all the photons coming out of E are of the same frequency. But as I have been mentioning from the start of this article I want a technique that is independent of frequency, so let’s see how we can fine tune this to eliminate this dependence. Since the time of travel between E and Ei is fixed, the phasor direction for each frequency photon falling at Ei is different but fixed. So at the most we would have to keep a table of frequency versus the phasor direction. The reference for the phasor direction will be obtained from the photon traveling on the optical axis, from which the corresponding phasor directions for other frequencies can be calculated. For a focused image the values obtained at Ei should not deviate from the table. We haven’t really analyzed if there is any chance that even for an out of focused image the table can match. To know this let’s look at how we are going to eliminate the virtual particle concept using this theory.

The above diagram shows a point in perfect focus; all the particles emanating from the point E are traveling for the same amount of time to meet at Ei. The phasor completes 36,000 circles for every inch it travels for red light and is even more for other visible frequencies. This creates periodicity in terms of the distance along the axis where virtual particles can be found. It is equivalent to sampling the optical axis with the frequency of the axial photon. If the same photon were to be placed on any of these samples they would end up at Ei with the phasor pointing in the same direction. Even though the virtual particles are found all along the axis, due to sampling we are able to eliminate a lot of them. Earlier a virtual particle could be formed by a photon coming from anywhere in space along the line that passes through the virtual particle at any angle. Now that doesn’t hold good either. To analyze this let’s consider a virtual particle on one of the samples between the point E and the lens, say ‘Ev’. For this to act as a virtual particle, depending on the frequency of the photon there are a fixed and periodic set of locations from where the photon can come from. So I assume that there is a high probability that there will at least be one photon that will go against the rules. For example lets assume that all the photons are of the same frequency. Consider the three heavily dotted lines that are passing through the point ‘Ev’. The dots mean that the photon can come from one of these places only. The dots are again nothing other than sampling, and changes for photons of different frequencies. So of the infinitely many photons passing through the point ‘Ev’ from all the directions, it is highly likely that at least one photon fails to lie on the dot. The same rule applies to all the virtual particles positions on the axis, even those that are beyond E.

        With all these assumptions in place, can we say that this new technique can be implemented? Well I already have a problem. Till now we have unknowingly made an assumption that the direction of all the phasors at the particle are reset, but in reality we never know if this is true. If this isn’t true, then pack your bags guys, there is no way to find out if the phasors are equivalently pointing in the same direction at Ei. This boils down to the same problem; there is no difference between a real and a virtual point.