If you look at water-splitting reactions in nature, you can see that they don’t involve any energy at all: water and light are both going and coming from somewhere. But we call it free energy potential energy . That’s what we’re trying to describe in thermodynamics.

You can’t just look at one thing, such as sunlight, and describe all the phenomena around it. That’s what we’re trying to do. You can look at one factor, such as a solar charge or a chemical reaction, and then say that that’s all you can describe. One good case for this was the work of Charles Perrault and Harold E. Shanks [1905–2005].

Porat: What was it that led to the notion of the wave function?

Healy: The answer is that the wave function had originally been known as the Poisson-Gaussian function. The Poisson-gaussian function can be a special case of a more general theory that is known as a Fourier analysis.

That Poisson-gaussian function is a kind of equation, not just with the equation of state, which is known as the function of a particular function, or a single element, but a function with the entire distribution. What a function has to do with all these different phenomena is to show how many different functions that can exist.

The idea came not long after the development of quantum theory. As you pointed out, people had been trying to give mathematical expression to different physical phenomena but had given up after a while [1926.], because they were not able to give mathematical expression.

A few years after the development of quantum theory, George de Broglie invented the idea of quantum theory that would be able to give quantum physics the mathematical expression it needed. A decade later, Paul Dirac also found that if the function were finite, with the parameters set by a number of conditions that you set at the beginning of the calculation, you might be able to solve the equation of state.

This got people interested in what the Fourier analysis had done, and it gave them a way to actually try to define that equation of state for what people had long thought of as a discrete function. One way to think about that was to think of it as an array, with an element for every element in the equation of state. It’s that way if you have an array of five elements, or an array of two, or the two of two, the