WHY WILL LIGHT CHANGE DIRECTION IN LIGHT EXPERIMENT OF ALICE LAW? Han Erim November 3, 2010  Copyright 2009 © Han Erim All Rights Reserved SUMMARY   The velocity and behavior of a light beam moving towards a target in motion have not been measured or investigated under laboratory conditions. Light experiment of Alice Law gives us this opportunity. The experiment is carried out by reflecting the light between rotating mirrors in parallel with each other and having it on a target. The target of the light changes depending on the rotation velocities of the mirrors. In this essay, I will tell you the reason why light changes its direction. I have also prepared a big surprise for you in the forthcoming chapters. I leave the significance of the issue to your discretion. Lets use the mechanism in figure 2 in order to have a simpler view. We reflect the light between mirrors in parallel with each other for a couple of times. The light source is mounted on the mechanism and we can move the mechanism towards left or right.   When we think according to the reference system of the mechanism, we immediately have this idea: Moving the mechanism never changes the route of the light between the mirrors. This is a natural outcome, as physics laws are unchangeable in systems that move in a uniform movement. Such information is already enough for understanding that light will change direction in light experiment of Alice Law. The more we dilate the time that light stays between the mirrors, the further or the nearer we can move the arrival point of light. For this reason, it is obvious that light will change direction in light experiment of Alice Law. Figure 3 However, there is a detail here which must be dwelled upon. This question comes up here: How does light know that mirrors move? Indeed, if we approach the situation according the ground reference system, it is obvious that light behaves depending on the reference system of the mechanism. Classical mechanics answers that question this way: Depending on the velocity of movement of the mechanism, light is emitted with an extra momentum, in addition to its normal movement direction, as the light source is mounted on the mechanism. This momentum maintains that the route of light between mirrors does not change. It is not that important whether the light source is mounted on the mechanism or not, since light will gain this momentum once first refraction occurs.  As you see, it is meaningless to debate whether light will change direction or not in light experiment of Alice Law. Light will change its direction. However, it is necessary not to overlook and to discuss an important issue here, because light can not carry momentum.  Lets see how interesting and important the issue will become from this point on. Can light carry momentum? Lets think of an A and a B as two objects moving bilaterally in space. Assume that there is a torch on B as light source and the position of the torch is perpendicular to X axis (Figure 4). Lets think that we are on one of these objects. Let it be A. Question: Can we tell the velocity of Object A on which we are? Answer: No, we cant. We can only tell our velocity relative to Object B. Question: Can we accept A reference system, on which we are, as inert? Answer: Yes, we can. We dont know whether we are going or not, anyway. We can say that A is inert while B is in motion. These questions and answers are our reference points.         We think that we have chosen A as our reference system and we watch the instance from A. Here is our question: When should the torch be lit so that torch-light will reach A? There are two answers to this question: 1) If we consider that light should carry momentum, relative to the coordinate system of A the torch must be lit before it reaches X=0 point and light must travel on blue-colored Y axis, which belongs to B (this is the approach adopted by classical mechanics while explaining the instance of two parallel mirrors given above). Figure 5. 2) If we consider that light should not carry momentum, then relative to the coordinate system of A torch must be lit when it reaches X=0 point and light must travel on red-colored Y axis, which belongs to A. (This is the view of Alice Law. I can also say that it is partially this way according to Einsteins physics, as according to Einsteins Universal Velocity of Light postulate, velocity of light must be independent from the velocity of the source. I said partially because Einsteins physics does not have a clear answer for the question above). Figure 6. As we can see, there are two options before us. What is strange here is that none of these two views has been clearly acknowledged to be correct yet. I need to say that I find this quite surprising. Words fail to express the importance of this detail. It is extremely important to know this detail. How can we measure whether light carries momentum or not? I will answer this question using the example of two objects above once more. Now, let our reference system be B this time and lets regard B as inert. In this respect, A will be in motion relative to B. As changing our reference system cannot change what happens, both options we have written are valid also here. 1) If we consider that light should carry momentum, relative to the coordinate system of A the torch must be lit before it reaches X=0 point and light must travel on blue-colored Y axis, which belongs to B. Figure 7 2) If we consider that light should not carry momentum, then relative to the coordinate system of A torch must be lit when it reaches X=0 point and light must travel on red-colored Y axis, which belongs to A. Figure 8 Now, lets see what kind of an outcome we have obtained from this analysis: When the reference system of B is taken into consideration, light follows a straight way if it carries momentum, while it changes it direction if it does not. (Figure 9) Now we can say with what kind of an experiment we can determine this detail. How can we experimentally determine whether light carries momentum or not? We place a rotatable disc in the center of a square-shaped plate. We dont need to use any mirrors here as we will not reflect light. Our aim is to take the photo of light on the plate. If we adopt the approach above, B becomes the light source, while A becomes the rotating disc. Figure 10 As the disc rotates, we radiate light on the whole plate from a place as far as possible in the form of a very thin line and take its photo. This is what Light Experiment of Alice Law actually is and this is what should be conducted. 1) If light carries momentum, we have to see in our photo that the line of light we have radiated on the plate has not gone astray. The lines both on the plate outside and on the disc inside will create an uninterrupted, straight line. Figure 11 2) If light does not carry momentum, then as light has to change its direction according to the rotation speed of the disc, we have to see in the photo that the line of light on the disc has slipped forwards in rotation direction of the disc. Figure 12 Conclusion and Discussion I havent explained the connection between this experiment and Alice Law here, as it is not necessary for now. It is also not sensible to discuss what Alice Law has said, classical mechanics has proposed; it is also meaningless to debate what is what according to Einsteins physics. This experiment is extremely fundamental and significant. This experiment regulates the general theory of physics. I also should say that this experiment will result in favor of Alice Law.   Now, I should ask the final question: Who will conduct this experiment?     Han Erim I have prepared the animation below so that you can examine the details and make analysis more easily. You can download the source codes here (Flash CS3 Actionscript 3.0). Establish: December 2001 Copyright © 2000-2010. Han Erim. All Rights Reserved.