Have you ever come accross somebody with a "Let There Be Light" reference followed by some weird looking formulas?
Here's the explanations what the reference and formulas are all about!
Text on T-Shirt You Have Seen
Here is the graphic on the t-shirt of what you have witnessed:
Let us find out what this t-shirt means. What did the person want to tell us?
Actual reference of "Let There Be Light"
It is quite common that the phrase actually stems from the book of Genesis , specifically 1:3, the third verse of the first chapter. The verse goes:
God said, 'Let there be light,' and there was light.
For Christians, these are the first devine words of God in the bible.
The meaning of these word may not get more spiritual! Over thousands of years, these words have inspired people. They were eager to find meaning in themselves, God and creation.
The theoretical description of light most likely had a likewise spiritual meaning. In fact there are a lot of references in academia for this important verse.
See for example the following inscription at Carnegie library in Edinburgh:
And this is the connection to the text on the t-shirt that we seek.
Meaning of Text on T-Shirt
The equations that you have seen are called "Maxwell's Equations"
These equations govern the theory of electromagnetism / electrodynamics. This site is about this very theory!
Using some basic mathematic tricks, Maxwell's Equations can be used to derive certain phenomena. One of these phenomena is the explanation of free-space electromagnetic radiation, also known as "light".
So the joke may be interpreted in the following way: If God was to create light, then he must have formulated Maxwell's Equations!
Now I don't know if this connection is actually some kind of blasphemy. I hope not.
We might simply interpret the t-shirt in a way that is honoring both Christianity and natural sciences as well. It might be interpreted as "look, we have understood this piece of nature that God has created for us".
Nevertheless, you have all the facts at hand. Decide for yourself what the true message of the t-shirt owner is!
You might have come accross the t-shirt in other forms, such as ∇·B(r,t) = 0. But they all refer to Maxwell's Equations in one form or another.
There are a couple of different formulations of the same story. Essentially, the message is all the same:
Maxwell's Equations provide a fundamental description of light.
If God created light, he must have formulated Maxwell's Equations!