Light waves travel in empty space but what medium transmits them? There is no sound in space because no air molecules transmit it, but light still comes from the sun and stars. How can light travel in space that has no matter?
Waves travel on a pool when water moves, but a cork floating on it just bobs up and down as waves pass it. The waves don’t push the cork along because water doesn’t move in the wave direction, it moves up and down. What moves as a wave isn’t the water, but it’s up-down surface displacement, so when a pebble drops on a still pool, that disturbance spreads as ripples. Waves are vibrations spreading in a medium, so why is light different?
A transverse wave vibrates at right angles to its movement direction. Water waves are transverse waves because the water moves vertically as the wave spreads horizontally. Light is also a transverse wave but in three dimensions not two. It is said to have no medium because it moves in empty space but if space is a three-dimensional surface, then light could vibrate on space.
Current physics allows this because relativity lets our space curve, and quantum theory lets light vibrate into a dimension outside space. If space is something not nothing, it can host light as a transverse wave. Light travels in a vacuum, so it either vibrates nothing at all, which denies how waves work, or it vibrates space itself. The simpler option is that light is a vibration on space itself.
Why then don’t we see light waves moving up and down as water waves do? We know that light vibrates, but a ray of light seen from the side can’t be seen to move up or down. The answer is that everything we see is based on light, but a transverse wave can’t leave the surface it vibrates on, so light is sequestered to our space (Randall, 2005). A transverse wave can’t move in its amplitude direction, so light vibrates into a dimension that we can’t see. This might seem unacceptable, but reverse engineering lets us deduce unseen causes.
What then moves when light moves? According to physical realism, nothing does, but in quantum realism, the quantum network does. Quantum theory describes it as a three-dimensional rotation orthogonal to space. In simple terms, it sets a circle of values that are positive or negative displacements on space. If this circle completes at one point, it is empty space, but divided over more points it becomes a wave of light (Figure 2.7). Chapter 3 gives more details, but essentially light waves are positive-negative displacements on a surface, just as water waves are. What moves when light moves are quantum wave displacements.
Light waves are simple quantum waves but what is vibrating? Schrödinger called them matter density waves because high values make matter more likely to exist there, but quantum waves aren’t made of matter. Born called them probability waves because their amplitude squared at a point is the probability that something exists there, but a probability is just a number. We expected the ultimate reality to be matter, but it isn’t. The quantum waves that predict physical events aren’t based on mass, momentum, velocity or any other property of matter. The position taken here is that they are waves of existence, generated by the quantum network, that can manifest as space, light, or matter.