The return of the vacuum tubes

Long ago, I took a class in eletronics. At the time, I had no mentor, no one to really encourage me to give serious consideration of the potential power of electronics. My teacher, Mr. Vallens, had a terrible lisp and he just didn’t do the subject justice. And in that class, I was working with vacuum tubes.

Vacuum tubes? You mean like in our old TV? I remember them well. Little bulbs of glass with pins on the bottom and little metal plates sealed in vacuum, inside. They would pop like a light bulb when you smash ’em. Obsolete, right? Do you know that there are people fitting out stereo systems with vacuum tubes to pass their digital music through tubes to give it that “analog” sound? You know, a sort of warm and fuzzy music?

Then I learned about integrated circuits and chips, but only superficially. I thought that with those chips, the vacuum tube was dead. I learned about Moore’s Law, the one that says that the number of transistors we can pack on a chip will double every 18 months. And for a long, long time, that has held true.

But there is talk about Moore’s Law coming to an end in 2025. There is just so much you can do with silicon. We can’t make it go much faster than 5 GHz without frying the chip. That’s 5 billion clock cycles a second. The latest i7 chips from Intel clock out around 5 Ghz.

So chipmakers got into parallel processing with multiple cores all working together. I think the big chips, the Xeons are coming out with 8 cores now. The latest gaming i7s are coming out with 8 cores, too.

There has also been a lot of talk about quantum computing. But that is going to be a 30 year quest. There are tons of problems with it that must be overcome to even make it work and apply it to every day devices that you and I use in our homes and at work.

So it was with some surprise that I read of an Australian lab that had built an Air Channel Transistor. There are many interesting things about this type of transistor, and we’ll call it an ACT for short. It doesn’t use silicon, it uses metal. It passes current through about 35 nanometers of air to work, so technically, it’s not really a vacuum tube, but it’s close.

But here is what caught my eye: The theoretical limits of such a device are in the terahertz range…