What We Can Do Today

Now I'd like to talk about what we can do today, as compared to what we were doing in those days. Back then, I was speaking about machinery as well as writing, computers, and information, and although this talk is billed as being about machinery, I'll also discuss computers and information at the end.

My first slide illustrates what can be done today in making small things commercially. This is of course one of the chips that we use in computers, and it represents an area of about three millimeters by four millimeters. Human beings can actually make something on that small a scale, with wires about six microns across (a micron is a millionth of a meter, or a thousandth of a millimeter). The tolerances, dimensions, and separations of some of the wires are controlled to about three microns. This computer chip was manufactured five years ago, and now things have improved so that we can get down to about one-half micron resolution.

These chips are made, as you know, by evaporating successive layers of materials through masks. [Feynman uses "evaporating" as a generic term for all semiconductor process steps.] You can create the pattern in a material in several ways. One is to shine light through a mask that has the design that you want, then focus the light very accurately onto a light-sensitive material and use the light to change the material, so that it gets easier to etch or gets less easy to etch. Then you etch the various materials away in stages. You can also deposit one material after anotherthere's oxide, and silicon, and silicon with materials diffused into itall arranged in a pattern at that scale. This technology was incredible twenty-three years ago, but that's where we are today.

The real question is, how far can we go? I'll explain to you later why, when it comes to computers, it's always better to get smaller, and everybody's still trying to get smaller. But if light has a finite wavelength, then we're not going to be able to make masks with patterns measuring less than a wavelength. That fact limits us to about a half a micron, which is about possible nowadays, with light, in laboratories. The commercial scale is about twice that big.

So what could we do today, if we were to work as hard as we could in a laboratorynot commercially, but with the greatest effort in the lab? Michael Isaacson from the Laboratory of Submicroscopic Studies (appropriate for us) has made something under the direction of an artist friend of mine named Tom Van Sant. Van Sant is, I believe, the only truly modern artist I know. By truly modern, I mean a man who understands our culture and appreciates our technology and science as well as the character of nature, and incorporates them into the things that he makes.

I would like to show you, in the next slide, a picture by Van Sant. That's art, right? It represents an eye. That's the eyelid and the eyebrow, perhaps, and of course you can recognize the pupil. The interesting thing about this eye is that it's the smallest drawing a human being has ever made. It's a quarter of a micron across250 millimicronsand the central spot of the pupil is something like fifteen or twenty millimicrons, which corresponds to about one hundred atoms in diameter. That's the bottom. You're not going to be able to see things being drawn more than one hundred times smaller, because by that time you're at the size of atoms. This picture is as far down as we can make it.

Because I admire Tom Van Sant, I would like to show you some other artwork that he has created. He likes to draw eyes, and the next slide shows another eye by him. This is real art, right? Look at all the colors, the beauty, the light, and so forthqualities that of course are much more appreciated as art. (Maybe some of you clever lit guys know what you're looking at, but just keep it to yourselves, eh?)

To get some idea of what you're looking at, we're going to look at that eye from a little bit further back, so you can see some more of the picture's background. The next slide shows it at a different scale. The eye is now smaller, and perhaps you see how the artist has drawn the furrows of the brow, or whatever it is around the eye. The artist now wants to show the eye to us on a still smaller scale, so we can see a little more of the background. So in this next slide, you see the city of Los Angeles covering most of the picture, and the eye is this little speck up in the corner!

Actually, all these pictures of the second eye are LANDSAT pictures of an eye that was made in the desert. You might wonder how someone can make an eye that bigit's two and one-half kilometers across. The way Van Sant made it was to set out twenty-four mirrors, each two feet square, in special locations in the desert. He knew that when the LANDSAT passes back and forth overhead, its eye looks at the land and records information for the picture's pixels. Van Sant used calculations so that the moment the LANDSAT looked at a particular mirror, the sun would be reflecting from the mirror right into the eye of the LANDSAT. The reflection overexposed the pixel, and what would have been a two-foot square mirror instead made a white spot corresponding to an area of several acres. So what you saw in the first picture was a sequence of overexposed pixels on the LANDSAT picture. Now that's the way to make art! As far as I know, this is the largest drawing ever made by man.

If you look again at the original picture, you can see one pixel that didn't come out. When they went back to the desert, they found that the mirror had been knocked off its pedestal, and that there were footprints from a jack rabbit over the surface. So Van Sant lost one pixel.

The point about the two different eyes is this: that Van Sant wanted to make an eye much bigger than a normal eye, and the eye in the desert was 100,000 times bigger than a normal eye. The first eye, the tiny one, was 100,000 times smaller than a normal eye. So you get an idea of what the scale is. We're talking about going down to that small level, which is like the difference in scale between the two-and-one-half-kilometer desert object and our own eye. Also amusing to think about, even though it has nothing to do with going small, but rather with going bigwhat happens if you go to the next eye, 100,000 times bigger? Then the eye's scale is very close to the rings of Saturn, with the pupil in the middle.

I wanted to use these pictures to tell us about scale and also to show us what, at the present time, is the ultimate limit of our actual ability to construct small things. And that summarizes how we stand today, as compared to how the situation looked when I finished my talk in 1960. We see that computers are well on their way to small scale, even though there are limitations. But I would like to discuss something elsesmall machines.