Superluminality — Animation

Physics Beyond Our Senses

grb (230K)
Our reality is the end product of a cognitive process starting from the sensory inputs. Space and time, two aspects of reality, are just a part of the cognitive model created by our brain, much like sound and smell. Space is just a representation of the light inputs to our eyes. This is the reason for the speed of light is such a fundamental constant in our reality.

Assume that you are observing two particles moving away from each other at speeds close to the speed of light. For instance, you are standing close to the tunnel at CERN (not recommended!) where particles are whizzing by in opposite directions. Consider just two particles that are going in opposite directions. You know that in one second, the particles will be at a distance of 2c from each other. Or so it would seem to you, but Special Relativity (SR) says that if you were moving with one of the particles, the other particle wouldn’t be traveling at close to twice the speed of light, but still under the light speed barrier.

The Unreal Universe argues that the you would see the other particle going away from you slightly slower than the speed of light. In your perceived reality, the receding particle seems to obey SR, but this is a distortion to our reality brought about by the sensory modality.

SR (or at least the current interpretation of SR) insists that this has got nothing to do with our perception or the fact that we are sensing the receding particle using light. But I beg to defer. I know, this is very presumptuous. My argument is that if you are moving with one particle, the other particle is “in reality” moving away from you at twice the speed of light, but it just seems to be under the speed of light “in your reality.” This can actually be worked out using fairly simple algebra.

Once we accept that our perception of space (and consequently motion) is distorted by the finite speed of light, we can find compelling explanations for certain puzzling astrophysical phenomena. Let’s consider an object flying by at superluminal speed. How would we see it? This is what is shown in the animation. The object flies by across the rectangle and we are near the center of the bottom edge of the rectangle. The object emits light rays towards us at regular intervals. (Well, the object emits light rays in all directions at all times, but we are interested in only the ones are in our direction.) So we can propagate the light rays towards us. We see the object only when the first ray reaches us. As we can see from the animation, the first ray that reaches us is emitted somewhere near the center of the rectangle. Thus, we don’t see what the object is really doing. We see it appearing at the center of the rectangle (shown as a black dot, let’s call it the core) and then as two objects moving away from each other!

Now, let’s imagine that a bunch of objects (like a galaxy for instance) are moving together at a roughly constant superluminal speed. How would we see it? Following the same argument as in the animation, we can see that the group of objects would appear as a series of knots appearing in roughly symmetric jets. And roughly symmetric jets have been observed (mostly at radio frequencies) in the last few decades. They are called DRAGNs. (Images of DRAGNs are also available.)

Why do we see them in the radio frequency region? That brings us to the second part of the puzzle. In the animation, the change in the color of the two apparent objects (which I call phantoms) is supposed to represent the red shift of the object at the instant of it is observed. It is not really done to scale (as you will see from the Matlab function) here. It is a more involved calculation, and is shown in the article. The gist of it is that near the core, the objects appear with very high blue shift, and as they appear to move away from the core, the apparent emission becomes more red shifted. (Note that I have been careful to use “appear” and “apparent” all over the place.) The shift from blue to red does not represent a real shift in the energy of the emission, but is a part of our perception. And it is not just our human perception that gets fooled, all our measuring equipment (the Hubble telescope, for instance) operate using light or electromagnetic waves at the speed of light and are subject to the same distortions. The discussion is already more technical than I would have liked. A more thorough treatment is available in my book, and of course, all the technical details can be found in the article.

The evolution of the spectrum from heavily blue to heavily red shifts has fooled the astrophysicists for a while now. This is observed in what they call gamma ray bursts (GRBs). Due to the apparent change in the energy, these phenomena are associated with high energy, cataclysmic events like supernovae. In my opinion, they are much more likely to be artifacts of our perception.