Q&A: Carver Mead revolutionized computers. Can he do the same for physics?

Carver Mead isn’t impressed with complicated things. From his point of view, the bigger challenge is to take a complex system and find a way to simplify it without losing any of its core features.

In an era when integrated circuits for computers were painstakingly hand-painted by skilled lithographers, a microelectronics pioneer at Caltech came up with a plan that would allow anyone to easily fit thousands of transistors on a single microcontroller chip. His early 1970s innovation, called very large-scale integration, or VLSI, recently won him a prestigious award. Kyoto Prize 2022.

VLSI played a key role in the semiconductor revolution. This contributed to the exponential growth in the number of transistors that could be placed on a chip, reducing the size of computing devices and expanding their capabilities.

After studying the movement of electrons around a microchip, Mead became interested in the fundamental laws of physics that govern their movement. He took it upon himself to reformulate laws of electricity and magnetismwhich are taught now as they were when it was proposed James Clerk Maxwell in 1865.

Drawing on more than a century of modern physics experiments, Mead developed a more holistic picture of electromagnetic phenomena. His approach is based on quantum physics, which treats electrons, photons, and other building blocks of matter as waves and as particles.

Mead called the result “collective electrodynamics” and used the term as the title of a “little green book” on the topic, which he published in 2001. honorary professor at Caltech, he continues to work on this and other projects.

He told The Times about his journey from computer technology to fundamental physics.

Can you describe the basics of collective electrodynamics?

Think of an electron as a wave with a frequency corresponding to its energy and a wavelength related to its momentum. A superconductor contains a huge density of electrons bound together so they form a giant collective quantum state called a condensate. It’s like one huge electron.

When we make a wire from a superconductor, the propagation of the condensate wave through the wire is called electric current, and the frequency of the condensate wave is called voltage.

Thus, the components of electromagnetism are of quantum origin.

So you’re saying that it’s time to transform physics?

Quantum physics was not known at the time of Maxwell, so the quantum origin of electromagnetic interactions was not visible. Unfortunately, the electromagnetic theory is still taught in the old way.

What is the biggest difference between collective electrodynamics and the classical approach?

The importance of potential. Electrical engineering, of which our modern world is made, is built on the concept of potential. Many physicists don’t really understand the potential – they think it’s some kind of mathematical trick. But it’s actually a very, very deep concept.

In an electrical circuit, electronic condensation 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 provide new ideas that cannot be obtained using the standard theory of electricity and magnetism?

For standard stuff, you’ll get the same answer with both. But there are things that my approach makes easy to explain.

For example, take a quantized stream. It describes how something flows through a region in discrete quantities. In the 1970s, scientists noticed that magnetic flux around a tiny donut of superconductor behaved in this way. If you have a bunch of them, you will get a permanent magnet. That’s what a permanent magnet is – a collection of little superconducting loops, one in each atom. And they all lined up.

By extending this to two magnets, you can simply calculate what they’re doing to each other and you’ll get energy just fine. By thinking of it as a quantum system, collective electrodynamics gives the correct answer in a simpler way than the classical approach. And this is a deep fundamental thing that you can simply measure.

Some found it very interesting. But in retrospect, there is not enough explanation in the book, so it is very difficult for people to follow it. Once or twice a year, I get an email from someone that says, “I just grabbed what you wrote in your little green book and it changed my life.” And then it will be silent for another year or two.

Do you plan to expand it further?

Yes, I’m working hard on it.

Do you think it would be beneficial to educate the next generation of physicists in such a new, holistic way?

We are constantly developing new things in physics. Let’s just say that as an approximation, we have a doubling of knowledge every five or ten years. After a few of them it will no longer be possible to train people because there are too many new things.

So you really only have two options. First, you can get narrower and narrower, learning more and more about less and less, until you know everything about nothing. Or you can go back and realize that the new knowledge that we have allows for an incredibly deeper understanding of the field and its conceptual relationships.

It is widely believed that new science leads to new innovations. Is it always like this?

This is almost never true.

Most of what is happening is not at all in line with the spirit of the times. It’s something that people get creative and go and try, and most of it doesn’t work. Most of the things I did didn’t work, but sometimes I get what works. And it’s really good!

What other innovations are you working on?

I spent a lot of time working on the optimal organization of information systems. A conventional programmed computer, such as your laptop or smartphone that we use today, is very wasteful of its resources. He does one simple thing and spends a lot of energy doing every simple thing.

We’re starting to develop ways to use silicon technology with transistors to mimic what animal brains do. If you study the nervous system of animals, you will see that its organization is very different from that of a general purpose computer, and it is unusually energy efficient – our brain only needs about 20 watts to work.

As an emeritus professor, I have time to think deeply about things, to make efforts like a little green book, and to be interested in things like, for example, what is happening in the brain.

This interview has been edited for length and clarity.