Around 1850, a scientist, Sir George Stokes, was amazed that Fluorite was green in the shade and strong blue in direct sunlight. This ability to change color under a different light source, he named “fluorescence”. Fluorescence is the light-emission by certain substances when they are activated by ultraviolet (UV) light. The emission disappears when the activation is removed.
While patiently waiting for the shortwave UV lamp I ordered to be shipped, I read that history on their web site, ultraviolet-tools.com. I have a collection of minerals that fluoresce under both longwave (aka blacklight UV-A) and shortwave (UV-B and UV-C), but they usually have much more brilliant colors under shortwave UV radiation. So why do objects fluoresce? I had to learn more about light and its wavelengths.
The color of an object is determined by the frequency (wavelength) of the electromagnetic radiation that reflects back. If a substance absorbs all the wavelengths except red, we see red light reflecting back, and the object appears to be red. So this is crucial to understand about fluorescence: when an invisible lightwave in the ultraviolet bandwidth irradiates a particular mineral such as fluorite, that mineral’s electrons are excited such that they reflect back the color blue in the visible spectrum rather than the shaded color of green.
In Paul Doherty’s article “Fluorescent Probing“, he also discusses the related phenomenon of phosphorescence, which is the “glow-in-the-dark” effect of certain chemicals commonly infused into plastic toys. Here he compares fluorescence and phosphorescence:
A simple definition of fluorescence is that it is light emitted by an object excited by light, where the emitted light is of a different color, i.e. lower energy, than the exciting light, and where the emitted light stops immediately after the exciting light is turned off. The light will turn off in as little as 10-8 seconds.
In phosphorescence, on the other hand light continues to be emitted after the exciting light is turned off. The light will continue to be emitted for seconds or even hours.
A more advanced definition of phosphorescence is that it is temperature dependent while fluorescence is independent of temperature. Hot phosphorescent objects will glow more brightly for a shorter time than cold ones.
And here I thought that holding a phosphorescent toy under a light bulb was “storing up” glow power, when it is actually just absorbing the heat of the bulb!
Further, Doherty states that liquid detergents such as Tide also fluoresce:
It is a cultural phenomenon that we in the United states correlate cleanliness with the bluish-white appearance of white fabrics. Detergent manufacturers know this and add a colorless dye to the liquid detergents. This dye absorbs ultraviolet and emits blue light.
A typical fluorescent whitening agent for North American laundry detergent is [C50H44N2] 1,4-bis(styryl) benzene. That is quite odd to me, that a company would secretly stain your clothes with UV-absorbing dyes to make them look “whiter!”
In my Exodus reading for today, 34:29-35 says:
29 It came about when Moses was coming down from Mount Sinai (and the two tablets of the testimony were in Moses’ hand as he was coming down from the mountain), that Moses did not know that the skin of his face shone because of his speaking with Him. 30 So when Aaron and all the sons of Israel saw Moses, behold, the skin of his face shone, and they were afraid to come near him. 31 Then Moses called to them, and Aaron and all the rulers in the congregation returned to him; and Moses spoke to them. 32 Afterward all the sons of Israel came near, and he commanded them to do everything that the Lord had spoken to him on Mount Sinai. 33 When Moses had finished speaking with them, he put a veil over his face. 34 But whenever Moses went in before the Lord to speak with Him, he would take off the veil until he came out; and whenever he came out and spoke to the sons of Israel what he had been commanded, 35 the sons of Israel would see the face of Moses, that the skin of Moses’ face shone. So Moses would replace the veil over his face until he went in to speak with Him.
So, when Moses’ face became phosphorescent when he was in the presence (or radiation) of the Lord God, and I would venture to say that anyone’s face might do that. I knew that I had read in the bible that Moses’ glowing face began to fade after a certain period of time apart from the Lord’s presence, but I couldn’t remember where. I found it in the 2nd letter of Paul to the Corinthians, 3:12-13:
12 Therefore having such a hope, we use great boldness in our speech, 13 and are not like Moses, who used to put a veil over his face so that the sons of Israel would not look intently at the end of what was fading away.
So using the principle of scripture interpreting scripture, I know that Paul is clarifying the passage in Exodus, giving me the understanding that Moses knew he had the most authority to teach God’s law while his face was phosphorescent, and when the glory faded, he would veil himself to “save face” until the next meeting with God in the tabernacle. If I were Moses, I would have dyed my veil with 1,4-bis(styryl) benzene!
Continuing with 2 Cor. 3:14-18;
14 But their minds were hardened; for until this very day at the reading of the old covenant the same veil remains unlifted, because it is removed in Christ. 15 But to this day whenever Moses is read, a veil lies over their heart;16 but whenever a person turns to the Lord, the veil is taken away. 17 Now the Lord is the Spirit, and where the Spirit of the Lord is, there is liberty. 18 But we all, with unveiled face, beholding as in a mirror the glory of the Lord, are being transformed into the same image from glory to glory, just as from the Lord, the Spirit.
So the cool thing is that if as a Christian I turn to the Lord and respond to His leading, the unfading fluorescence of the Holy Spirit will reflect back out from my heart for all to see. Indeed, when I act as a servant and not a star, people around me recognize this glow and praise God. This is why I desire to abide in Christ, so that I remain in His will.
Too often I am tempted to hide under a Tide-whitened religious veil, and inevitably I sound stupidly pious. So I pray that with an unveiled face, I would let God speak to me through scripture like He did to Moses in Exodus 33:11,“Thus the Lord used to speak to Moses face to face, just as a man speaks to his friend.” That way I would instead fluoresce with the glory of Christ through my works.
I think about how I fear the sun so much more than I fear the Lord! I am vigilant to wear the covering of a wide-brimmed hat outside, because UV light exposure quickly sunburns my face. And I know that continued ultraviolet definance will result in a shortened life through skin cancer. In Proverbs 9:10-11, God says:
The fear of the Lord is the beginning of wisdom,
And the knowledge of the Holy One is understanding.
11 For by me your days will be multiplied,
And years of life will be added to you.
How much more can the Lord imperil my life when I try to live outside the covering of the blood of our Lord Jesus Christ? This fluorescence metaphor is starting to sound a little corny, but I think there’s a lesson here.
The invisible light of God’s holiness shines on us all. If we have been changed into a fluorescent mineral through the finished work of Jesus on the cross; then when we abide in the UV light of the Spirit we will reflect a special, visible wavelength back out that is hallowed, and we have the liberty to walk in the heat of the day. If we don’t, then the fiery heat of his holiness naturally induces us to cower in the darkness, or risk exposing the nakedness of our sin and being burned with unquenchable fire.