Einstein concluded that the speed of light is constant from how our world behaves, but couldn’t explain why light has that speed and no other. Why then does light travel at a constant speed in space? If light is particles moving, why can’t we nudge them to go at the speed of light plus one? What sets the speed limit of our universe? The answer, according to physics, is that:
“… the speed of light is a constant because it just is, and because light is not made of anything simpler.” (Laughlin, 2005), p15
Yet “because it just is” has never been a very satisfactory answer in science. The speed of a particles depends on its mass, but photons have no mass, so why can’t they go at any speed? In contrast, if light is a wave, its speed will depend on the medium that transmits it. Light as a processing wave on a network must move at the rate if that network, so how fast does the quantum network run?
A 5GHz computer network runs at 5,000,000,000 cycles per second. That seems very fast but Planck time suggests that the quantum network cycles at an astonishing 1045 times a second! Planck time is the smallest possible time scale in our universe, and Planck length is the smallest possible distance, and sure enough, dividing this distance by this time gives the speed of light (Note 1). The speed of light then, like every wave, is limited by the speed of the medium that transmits it.
Note that even the term “speed of light” betrays a particle bias, as it assumes that light particles set their own pace. Waves don’t do that. They can only move as fast as their medium allows, so if space is that medium, what we call the speed of light is actually the speed of space.
Why then does light slow down when it moves in water? Again it is our particle bias. If light moves in water, we assume the medium is water, and if it moves in glass, we assume the medium is glass, but if it moves in space, we say it has no medium and is a wave of nothing, which is inconsistent! Surely light has the same medium in every case. If the quantum network transmits light in space, then when it travels through water, it will be the same. Light then slows down in water because the network has other things to do, namely generate water matter. Light slows down when the quantum network is busy for the same reason that a game slows when the computer is busy.
Does light moving at different speeds according to local load cause problems? Fortunately, the quantum network still processes photons in strict sequence, one after the other, like cars in a queue. Each point handles the photon it has, then accepts the next in line, so even if it runs slower, say in a gas nebula, they still arrive in lock-step order. This maintains causality, as if one photon could overtake another, we might see an object arrive before it left! Causality requires photons to stay in sequence and the quantum engine rigorously maintains this.
Note 1: The speed of light c = LP/TP, where LP is a Planck length of 1.616×10−35meters and TP is Planck time of 5.39 × 10−44 of a second. This gives the speed of light as 299,792,458 meters per second (see here).
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