Fluorescence is a phenomenon in which a molecule emits light of a specific wavelength when it is activated by light of another specific wavelength. We call these the emission and excitation wavelengths, respectively. For example, GFP (which you can read about here) emits green light when it is activated by blue or UV light.
Sometimes the activating or exciting light is from another fluorophore. When fluorophore 1 is excited, it emits a wavelength of light that excites fluorophore 2. This phenomenon is called Förster Resonance Energy Transfer, or FRET.
Fluorescence, specifically FRET, reminds me of the gospel because it is an analogy for how humanity needs Jesus to embrace good.
The gospel story begins at the beginning of all time. God brought the universe into existence, and eventually, humanity. Unlike the rest of creation, God made humanity to share in his good rule over the earth and to share a special relationship with him. But humanity didn’t agree to this. Humans wanted to rule, but they wanted to do it on their own terms. God was getting in the way of what they wanted to do. But apart from God, humanity had no source of goodness. Humanity entered darkness.
We can think of ourselves as fluorophores, and of the light we emit as goodness. We like to think that we can glow on our own. Surely we can be good people if only we figure out what is good, commit to doing it, and apply ourselves, right? Except in practice, we know this isn’t actually true. We struggle to identify good from evil, and even if we think we know what’s good, we struggle to choose good over selfishness, pride, anger and revenge. We don’t always choose the good, even when we want to.
The problem is that fluorescent molecules cannot just glow on their own. They fully depend on the energy of the excitation light to emit light themselves. A fluorophore cannot emit light in complete darkness. We also require energy from an exciting light. But what is our exciting light?
Fluorophores are always excited by a wavelength with higher energy than the one they emit. The blue and UV light that GFP absorb have more energy than the green light that GFP emits. So then, our exciting light must glow more than we glow. It must emit more goodness than we can. Another human fluorophore just like us cannot supply our exciting light. Green excitation cannot yield green emission.
Jesus of Nazareth demonstrated perfect goodness. He is God incarnate, that is, God in human form. While he walked on earth, Jesus had a perfect relationship with God the Father. He loved God and he loved humanity so much that he died for you and for me on a Roman cross. Jesus emits far more goodness than we ever can.
In FRET, fluorophore 1 connects fluorophore 2 to the ultimate exciting light source. Remember, a fluorophore cannot use just any wavelength of light to emit its own; excitation wavelengths are within a range. Apart from God, we are not able to use God’s goodness and power as exciting light. It isn’t in range for us. But Jesus intercedes. Jesus’ light makes our light possible. Jesus’ beautiful glow serves as the means for our own glow.
But there is one last critical thing to know about FRET: FRET only works when fluorophores 1 and 2 are close to one another. In fact, FRET is a method that scientists use to determine the distance between two molecules that are interacting. If fluorophore 2 is far from fluorophore 1, there is no energy transfer. Fluorophore 2 remains dead. But when the two fluorophores draw near, the energy transfer is able to take place and fluorophore 2 can be seen emitting its light.
Jesus got close to us. He came to this earth as a human to be close to us. He died on our behalf to place himself between us and God’s light, to connect us to the exciting light of God’s ultimate goodness. Then he rose from the dead to invite us near to him.
When we draw near to Jesus, when we accept him and seek him, when we place our faith in him, his perfect glow is able to activate us. Proximity to Jesus empowers us towards goodness. It empowers us to love God and experience God’s love, like a child and his father, for all eternity. It empowers us to release our need to rule in selfish ambition and to embrace ruling with God in selfless goodness. We are called “good” because he is good. We glow because he glows.
Science Magnifies 