The Constant That Reveals

We have been building toward something, and now it is time to name what we are building toward. The question is simple. If time is a created thing, if God is unbound by time, if aevum proves that temporal existence without entropy is possible for created beings, then what bridges the gap between the eternal and the temporal? What connects God who is unbound and human beings who are bound?

The answer is light.

Not metaphorically. Not merely theologically. Light — the thing physicists measure, the thing that travels at 299,792 kilometers per second through a vacuum, the thing that every observer in the universe measures at exactly that speed regardless of how fast the observer is moving. Light is the constant. Light is the bridge. And understanding why light is constant in a way nothing else is constant opens the door to understanding why God can be both completely transcendent and completely intimate.

To understand this, we need to look at what happens at the speed of light. And to do that, we need to step into special relativity for a moment.

Einstein showed that space and time are not separate. They are woven together. One consequence is that time is relative. The faster you move, the slower your clock ticks relative to a stationary observer. If you accelerated to near the speed of light, your clock would tick very slowly. Years would pass for you while decades passed for people on Earth. This is not a theory. It is measured. Particles in accelerators live longer when they are moving at near-light speeds than when they are at rest, because time literally passes more slowly for them.

But there is something remarkable about light itself. Light always travels at exactly the speed of light. Always. No matter what. If you are standing still, light passes you at 299,792 kilometers per second. If you are moving toward the light at half the speed of light, the light still passes you at 299,792 kilometers per second. This makes no intuitive sense. But it is true, and it is the foundation on which relativity rests.

The consequence is strange. For a photon — a particle of light — time does not pass at all. From the photon's own perspective, the journey from a star across billions of light-years and into your eye happens instantaneously. Emission and absorption are simultaneous. The photon travels through time — through the duration of the universe — and experiences no duration. It lives in an eternal now.

Light, in other words, partakes of eternity while remaining physical. Light is the one physical thing in the universe that is not subject to time in the way we are subject to time.

This is not accident. This is revelation.

The reason light is constant is that it is massless. A massive particle requires energy to accelerate, and the energy required grows without bound as the particle approaches the speed of light. To accelerate a massive particle to the speed of light would require infinite energy. It cannot be done. Massive particles are bound by time. But light, which has no rest mass, is not subject to this limit. Light exists at the speed of light necessarily, the way God exists in eternity necessarily.

And this is where the theology lands. If light is the one thing that bridges the eternal and the temporal, if light is the physical reality that partakes of eternity without ceasing to be physical, and if God is light — then God is not in some parallel realm separate from the creation. God is the constant that makes the creation intelligible. The speed of light is written into the fabric of spacetime itself. It is the speed at which gravity propagates. It is the speed at which causality operates. This speed is constant for all observers because it is the constant that makes observation possible.

When John writes that God is light, he is not reaching for poetry to describe something inexpressible. He is identifying the deepest constant in the structure of creation with the nature of the Creator. God is light means God is the invariant. God is the one reality that does not change relative to the observer's motion. God is the ground of all constancy.

John makes two claims about God's essence in his first letter. God is light, in 1 John 1:5, and God is love, in 1 John 4:8. These are not two competing essences but one essence named from two angles. Light is what the constant is in its self-disclosing presence. Love is what the constant is in its motion toward those who cannot reach the constant by their own motion. This chapter has worked out light. The next chapter will work out the asymptote, and the asymptote is where the second anchor has to do its distinct work — because light by itself is not yet motion toward the one not yet present, and what makes the descent a descent rather than a continued constancy is that love does what light alone would not.

If God is light, and if light experiences an eternal now, then God's presence to every moment is not the presence of a distant observer. It is the presence of the constant that makes those events intelligible. You cannot remove light from the universe and have the universe remain. The universe would collapse into darkness and meaninglessness. In the same way, you cannot remove God from your moment and have your moment remain. God is not an addition to your moment. God is the constant that makes your moment coherent.