Chapter 20. Infinitesimal Machinery

Revisiting "There's Plenty of Room at the Bottom"

In 1960, about 23 years ago, I gave a talk called "There's Plenty of Room at the Bottom," in which I described the coming technology for making small things. I pointed out what everybody knew: that numbers, information, and computing didn't require any particular size . You could write numbers very small, down to atomic size. (Of course, you can't write something much smaller than the size of a single atom.) Therefore, we could store a lot of information in small spaces, and in a little while we'd be able to do so easily. And of course, that's what happened .

I've been asked a number of times to reconsider all the things that I talked about 23 years ago, and to see how the situation has changed. So my talk today could be called "There's Plenty of Room at the Bottom, Revisited."

As I mentioned in the 1960 talk, you could represent a digit by saying it is made of a few atoms. Actually, you'd only have to use one atom for each digit, but let's say you make a bit from a bunch of gold atoms, and another bit from a bunch of silver atoms. The gold atoms represent a one, and the silver atoms a zero. Suppose you make the bits into little cubes with a hundred atoms on a side. When you stack the cubes all together, you can write a lot of stuff in a small space. It turns out that all the books in all the world's libraries could have all their informationincluding pictures using dots down to the resolution of the human eyestored in a cube 1/120 inch on a side. That cube would be just about the size you can make out with your eyeabout the size of a speck of dirt.

If, however, you used only surfaces rather than the volume of the cubes to store information, and if you simply reduce normal scale by twenty-five thousand times, which was just about possible in those days, then the Encyclopedia Britannica could be written on the head of a pin, the Caltech library on one library card, and all the books in the world on thirty-five pages of the Saturday Evening Post . I suggested a reduction of twenty-five thousand times just to make the task harder, because due to the limitations of light wavelength, that reduction was about ten times smaller than you could read by means of light. You could, of course, read the information with electron microscopes and electron beams.

Because I had mentioned the possibility of using electron beams and making things still smaller, six or eight years ago someone sent me a picture of a book that he reduced by thirty thousand times. In the picture, there are letters measuring about a tenth of a micron across [ passes the picture around the audience].

I also talked in the 1960 lecture about small machinery, and was able to suggest no particular use for the small machines. You will see there has been no progress in that respect. And I left as a challenge the goal of making a motor that would measure 1/64 of an inch on a side. At that time, the idea that I proposed was to make a set of handslike those used in radioactive systemsthat followed another set of hands. Only we make these "slave" hands smallera quarter of the original hands' sizeand then let the slave hands make smaller hands and those make still smaller hands. You're right to laughI doubt that that's a sensible technique. At any rate, I wanted to get a motor that couldn't be made directly by hand, so I proposed 1/64 of an inch.

At the end of my talk, Don Glaser, who won the Nobel prize in physicsthat's something that's supposed to be good, right?said, "You should have asked for a motor 1/200 inch on a side, because 1/64 inch on a side is just about possible by hand." And I said, "Yeah, but if I offered a thousand-dollar prize for a motor 1/200 inch on a side, everybody would say 'Boy, that guy's a cheapskate! Nobody's ever going to do that.'" I didn't believe Glaser, but somebody actually did make the motor by hand!

As a matter of fact, the motor's very interesting, and just for fun, here it is. First look at it directly with your eye, to see how big it is. It's right in the middle of that little circleit's only the size of a decimal point or a period at the end of a sentence . Mr. McLellan, who made this device for me, arranged it very beautifully, so that it has a magnifier you can attachbut don't look at it through the magnifier until you look at it directly. You'll find you can't see it without the magnifier. Then you can look through the magnifier and turn this knob, which is a little hand generator which makes the juice to turn the motor so you can watch the motor go around [ gives the McLellan motor to the audience to be passed around].