Q&A: Carver Mead revolutionized computers. Can he do the same for physics?
Carver Mead is not impressed by complicated things. For him, the bigger challenge is taking a complex system and finding a way to simplify it without missing any of its essential characteristics.
At a time when computer integrated circuits were painstakingly hand-painted by skilled lithographers, Caltech’s microelectronics pioneer created a design that made it easy for anyone to fit thousands of transistors onto a single microcontroller chip. His innovation from the early 1970s – dubbed Very Large Scale Integration, or VLSI – recently earned him the prestigious 2022 Kyoto Prize.
VLSI played a crucial role in the semiconductor revolution. It fueled the exponential increase in the number of transistors that could be placed on a chip, shrinking computing devices and expanding their capabilities.
After Mead conjured up the motions of electrons around a microchip, he became interested in the fundamental laws of physics that govern their motion. He took it upon himself to restate the rules of electricity and magnetism, which are taught today as they were taught when they were proposed by James Clerk Maxwell in 1865.
Drawing on more than a century of modern physics experiments, Mead developed a more holistic view of electromagnetic phenomena. His approach is based on quantum physics, which treats electrons, photons, and other building blocks of matter as both waves and particles.
Mead dubbed the result “collective electrodynamics” and used that term as the title of a “little green book” on the subject that he published in 2001. As Professor Emeritus at Caltech, he continues to work on this and other projects.
He spoke to The Times about his journey from computer technology to fundamental physics.
Can you describe the basics of collective electrodynamics?
Think of the electron as a wave, with a frequency equal to its energy and a wavelength equal to its momentum. A superconductor contains an enormous density of electrons that are coupled together to form a huge collective quantum state called a condensate. It’s like a giant electron.
If we make a wire from a superconductor, the propagation of the condensate wave along the wire is called electric current, and the frequency of the condensate wave is called voltage.
The components of electromagnetism are therefore of quantum mechanical origin.
So you’re saying the physics need an overhaul?
Quantum physics was not known in Maxwell’s time, so the quantum origin of electromagnetic interactions was not visible. Tragically, electromagnetic theory is still taught the old way.
What is the biggest difference between collective electrodynamics and the classical approach?
The importance of potential. The electrical engineering that has shaped our modern world is based on the concept of potential. Many physicists don’t really understand potential – they think it’s a mathematical trick. But it’s actually a very, very deep concept.
In an electrical circuit, the electron condensate in a wire is like water flowing through a pipe. We call its flow electric current and its pressure electric potential or voltage.
Does collective electrodynamics offer new insights that you can’t get with the standard theory of electricity and magnetism?
For the standard stuff, you’ll get the same answer with either. But there are things that can be explained more easily by my approach.
Let’s take the quantized flow for example. This describes how something flows through a region in discrete amounts. In the 1970s, scientists observed that this is how the magnetic flux behaved around a tiny donut made of a superconductor. If you have a few of these, you will get a permanent magnet. That’s a permanent magnet — a bunch of little superconducting loops, one in each atom. And they are all lined up.
Expanding this to two magnets you can just calculate what they do to each other and you get the energy beautifully. By looking at it as a quantum system, collective electrodynamics gives you the correct answer in a simpler way than the classical approach. And that’s a deep, fundamental thing that you can easily measure.
Some found it very interesting. But looking back, the book doesn’t have enough explanations that people find it very difficult to follow. Once or twice a year I get an email from someone that says, “I just grabbed what you said in your little green book and it changed my life.” And then there will be another, be silent for two years.
Are you planning further expansion?
Yes, I am working hard on that.
Do you think it would be helpful to educate the next generation of physicists in this new, holistic way?
We are constantly developing new things in physics. Let’s just say, as an approximation, we have a doubling of knowledge every five or ten years. After a few of these it won’t be possible to enlighten people because there’s just too much new stuff.
So you really only have two options. One is that you can get narrower and narrower, where you learn more and more about less and less, until you know everything about nothing. Or you can go back and find that the new knowledge we have allows for an incredibly deeper way of grasping the field and its conceptual relationships.
It is a common notion that new science leads to new innovations. Is that always true?
It’s almost never true.
Most of what’s happening doesn’t fit the mainstream zeitgeist at all. It’s what people get creative about and go out and try, and most of it doesn’t work. Most things I’ve done haven’t worked, but occasionally I get one that does. And it feels really good!
What other types of innovations are you working on?
I spent a lot of time working on the optimal organization of information systems. The commonly programmed computer – like your laptop or a smartphone – that we use today is very wasteful of its resources. It does one simple thing and it takes a lot of energy to do each simple thing.
We’re starting to think of ways that silicon technology could be used with transistors to emulate things that animal brains do. When you study the nervous systems of animals, the organization is very different from a general-purpose computer and is extraordinarily energy efficient – our brains only need about 20 watts to run.
As a professor emeritus, I have the time to think more deeply about things, to pursue endeavors like The Little Green Book, and to wonder about things like what happens in the brain.
This interview has been edited for length and clarity.
https://www.latimes.com/science/story/2022-07-02/q-a-carver-mead-revolutionized-computers-can-he-do-the-same-for-physics Q&A: Carver Mead revolutionized computers. Can he do the same for physics?