changelog shortlog tags branches changeset files revisions annotate raw help

Mercurial > hg > plan9front / lib/plentyofroom

changeset 7241: 4b6277dd0535
parent: 911b689ab615
author: cinap_lenrek@felloff.net
date: Fri, 17 May 2019 01:51:28 +0200
permissions: -rw-r--r--
description: mkone: fix man target (thanks Amavect)

Amavect wrote:
> mkone and mkmany have backwards targets for installing man pages.
> This patch makes 'mk man' actually work for mkfiles that include mkone.
> mkmany is not easily fixed without breaking changes.
> It may go without saying that external repos should write their own mkfiles.
1 There's Plenty of Room at the Bottom
2 
3 An Invitation to Enter a New Field of Physics
4 
5 by Richard P. Feynman
6 
7 This transcript of the classic talk that Richard Feynman gave on December
8 29th 1959 at the annual meeting of the American Physical Society at
9 the California Institute of Technology (Caltech) was first published in
10 Caltech Engineering and Science, Volume 23:5, February 1960, pp 22-36.
11 
12 __________________________________________________________________
13 
14 I imagine experimental physicists must often look with envy at men like
15 Kamerlingh Onnes, who discovered a field like low temperature, which
16 seems to be bottomless and in which one can go down and down. Such a
17 man is then a leader and has some temporary monopoly in a scientific
18 adventure. Percy Bridgman, in designing a way to obtain higher pressures,
19 opened up another new field and was able to move into it and to lead
20 us all along. The development of ever higher vacuum was a continuing
21 development of the same kind.
22 
23 I would like to describe a field, in which little has been done, but in
24 which an enormous amount can be done in principle. This field is not quite
25 the same as the others in that it will not tell us much of fundamental
26 physics (in the sense of, "What are the strange particles?") but it is
27 more like solid-state physics in the sense that it might tell us much
28 of great interest about the strange phenomena that occur in complex
29 situations. Furthermore, a point that is most important is that it would
30 have an enormous number of technical applications.
31 
32 What I want to talk about is the problem of manipulating and controlling
33 things on a small scale.
34 
35 As soon as I mention this, people tell me about miniaturization, and how
36 far it has progressed today. They tell me about electric motors that are
37 the size of the nail on your small finger. And there is a device on the
38 market, they tell me, by which you can write the Lord's Prayer on the
39 head of a pin. But that's nothing; that's the most primitive, halting
40 step in the direction I intend to discuss. It is a staggeringly small
41 world that is below. In the year 2000, when they look back at this age,
42 they will wonder why it was not until the year 1960 that anybody began
43 seriously to move in this direction.
44 
45 Why cannot we write the entire 24 volumes of the Encyclopaedia Brittanica
46 on the head of a pin?
47 
48 Let's see what would be involved. The head of a pin is a sixteenth of an
49 inch across. If you magnify it by 25,000 diameters, the area of the head
50 of the pin is then equal to the area of all the pages of the Encyclopaedia
51 Brittanica. Therefore, all it is necessary to do is to reduce in size all
52 the writing in the Encyclopaedia by 25,000 times. Is that possible? The
53 resolving power of the eye is about 1/120 of an inch – that is roughly
54 the diameter of one of the little dots on the fine half-tone reproductions
55 in the Encyclopaedia. This, when you demagnify it by 25,000 times,
56 is still 80 angstroms in diameter – 32 atoms across, in an ordinary
57 metal. In other words, one of those dots still would contain in its area
58 1,000 atoms. So, each dot can easily be adjusted in size as required by
59 the photoengraving, and there is no question that there is enough room
60 on the head of a pin to put all of the Encyclopaedia Brittanica.
61 
62 Furthermore, it can be read if it is so written. Let's imagine that
63 it is written in raised letters of metal; that is, where the black is
64 in the Encyclopedia, we have raised letters of metal that are actually
65 1/25,000 of their ordinary size. How would we read it?
66 
67 If we had something written in such a way, we could read it using
68 techniques in common use today. (They will undoubtedly find a better way
69 when we do actually have it written, but to make my point conservatively
70 I shall just take techniques we know today.) We would press the metal
71 into a plastic material and make a mold of it, then peel the plastic off
72 very carefully, evaporate silica into the plastic to get a very thin film,
73 then shadow it by evaporating gold at an angle against the silica so that
74 all the little letters will appear clearly, dissolve the plastic away from
75 the silica film, and then look through it with an electron microscope!
76 
77 There is no question that if the thing were reduced by 25,000 times in
78 the form of raised letters on the pin, it would be easy for us to read
79 it today. Furthermore, there is no question that we would find it easy
80 to make copies of the master; we would just need to press the same metal
81 plate again into plastic and we would have another copy.
82 
83 How do we write small?
84 
85 The next question is: How do we write it? We have no standard technique
86 to do this now. But let me argue that it is not as difficult as it first
87 appears to be. We can reverse the lenses of the electron microscope in
88 order to demagnify as well as magnify. A source of ions, sent through the
89 microscope lenses in reverse, could be focused to a very small spot. We
90 could write with that spot like we write in a TV cathode ray oscilloscope,
91 by going across in lines, and having an adjustment which determines the
92 amount of material which is going to be deposited as we scan in lines.
93 
94 This method might be very slow because of space charge limitations.
95 There will be more rapid methods. We could first make, perhaps by
96 some photo process, a screen which has holes in it in the form of the
97 letters. Then we would strike an arc behind the holes and draw metallic
98 ions through the holes; then we could again use our system of lenses and
99 make a small image in the form of ions, which would deposit the metal
100 on the pin.
101 
102 A simpler way might be this (though I am not sure it would work):
103 We take light and, through an optical microscope running backwards,
104 we focus it onto a very small photoelectric screen. Then electrons
105 come away from the screen where the light is shining. These electrons
106 are focused down in size by the electron microscope lenses to impinge
107 directly upon the surface of the metal. Will such a beam etch away the
108 metal if it is run long enough? I don't know. If it doesn't work for a
109 metal surface, it must be possible to find some surface with which to
110 coat the original pin so that, where the electrons bombard, a change is
111 made which we could recognize later.
112 
113 There is no intensity problem in these devices not what you are used
114 to in magnification, where you have to take a few electrons and spread
115 them over a bigger and bigger screen; it is just the opposite. The light
116 which we get from a page is concentrated onto a very small area so it
117 is very intense. The few electrons which come from the photoelectric
118 screen are demagnified down to a very tiny area so that, again, they
119 are very intense. I don't know why this hasn't been done yet!
120 
121 That's the Encyclopaedia Brittanica on the head of a pin, but let's
122 consider all the books in the world. The Library of Congress has
123 approximately 9 million volumes; the British Museum Library has 5 million
124 volumes; there are also 5 million volumes in the National Library in
125 France. Undoubtedly there are duplications, so let us say that there
126 are some 24 million volumes of interest in the world.
127 
128 What would happen if I print all this down at the scale we have been
129 discussing? How much space would it take? It would take, of course, the
130 area of about a million pinheads because, instead of there being just
131 the 24 volumes of the Encyclopaedia, there are 24 million volumes. The
132 million pinheads can be put in a square of a thousand pins on a side, or
133 an area of about 3 square yards. That is to say, the silica replica with
134 the paper-thin backing of plastic, with which we have made the copies,
135 with all this information, is on an area of approximately the size of 35
136 pages of the Encyclopaedia. That is about half as many pages as there are
137 in this magazine. All of the information which all of mankind has ever
138 recorded in books can be carried around in a pamphlet in your hand –
139 and not written in code, but as a simple reproduction of the original
140 pictures, engravings, and everything else on a small scale without loss
141 of resolution.
142 
143 What would our librarian at Caltech say, as she runs all over from one
144 building to another, if I tell her that, ten years from now, all of the
145 information that she is struggling to keep track of – 120,000 volumes,
146 stacked from the floor to the ceiling, drawers full of cards, storage
147 rooms full of the older books – can be kept on just one library card!
148 When the University of Brazil, for example, finds that their library is
149 burned, we can send them a copy of every book in our library by striking
150 off a copy from the master plate in a few hours and mailing it in an
151 envelope no bigger or heavier than any other ordinary air mail letter.
152 
153 Now, the name of this talk is "There is Plenty of Room at the Bottom"
154 – not just "There is Room at the Bottom." What I have demonstrated
155 is that there is room – that you can decrease the size of things in a
156 practical way. I now want to show that there is plenty of room. I will
157 not now discuss how we are going to do it, but only what is possible
158 in principle – in other words, what is possible according to the laws
159 of physics. I am not inventing anti-gravity, which is possible someday
160 only if the laws are not what we think. I am telling you what could be
161 done if the laws are what we think; we are not doing it simply because
162 we haven't yet gotten around to it.
163 
164 Information on a small scale
165 
166 Suppose that, instead of trying to reproduce the pictures and all the
167 information directly in its present form, we write only the information
168 content in a code of dots and dashes, or something like that, to represent
169 the various letters. Each letter represents six or seven "bits" of
170 information; that is, you need only about six or seven dots or dashes
171 for each letter. Now, instead of writing everything, as I did before,
172 on the surface of the head of a pin, I am going to use the interior of
173 the material as well.
174 
175 Let us represent a dot by a small spot of one metal, the next dash by an
176 adjacent spot of another metal, and so on. Suppose, to be conservative,
177 that a bit of information is going to require a little cube of atoms 5
178 x 5 x 5 – that is 125 atoms. Perhaps we need a hundred and some odd
179 atoms to make sure that the information is not lost through diffusion,
180 or through some other process.
181 
182 I have estimated how many letters there are in the Encyclopaedia,
183 and I have assumed that each of my 24 million books is as big as an
184 Encyclopaedia volume, and have calculated, then, how many bits of
185 information there are (10^15). For each bit I allow 100 atoms. And it
186 turns out that all of the information that man has carefully accumulated
187 in all the books in the world can be written in this form in a cube
188 of material one two-hundredth of an inch wide – which is the barest
189 piece of dust that can be made out by the human eye. So there is plenty
190 of room at the bottom! Don't tell me about microfilm!
191 
192 This fact – that enormous amounts of information can be carried in an
193 exceedingly small space – is, of course, well known to the biologists,
194 and resolves the mystery which existed before we understood all this
195 clearly, of how it could be that, in the tiniest cell, all of the
196 information for the organization of a complex creature such as ourselves
197 can be stored. All this information – whether we have brown eyes,
198 or whether we think at all, or that in the embryo the jawbone should
199 first develop with a little hole in the side so that later a nerve can
200 grow through it – all this information is contained in a very tiny
201 fraction of the cell in the form of long-chain DNA molecules in which
202 approximately 50 atoms are used for one bit of information about the cell.
203 
204 Better electron microscopes
205 
206 If I have written in a code, with 5 x 5 x 5 atoms to a bit, the question
207 is: How could I read it today? The electron microscope is not quite good
208 enough, with the greatest care and effort, it can only resolve about 10
209 angstroms. I would like to try and impress upon you while I am talking
210 about all of these things on a small scale, the importance of improving
211 the electron microscope by a hundred times. It is not impossible; it is
212 not against the laws of diffraction of the electron. The wave length of
213 the electron in such a microscope is only 1/20 of an angstrom. So it
214 should be possible to see the individual atoms. What good would it be
215 to see individual atoms distinctly?
216 
217 We have friends in other fields – in biology, for instance. We
218 physicists often look at them and say, "You know the reason you fellows
219 are making so little progress?" (Actually I don't know any field where
220 they are making more rapid progress than they are in biology today.)
221 "You should use more mathematics, like we do." They could answer us –
222 but they're polite, so I'll answer for them: "What you should do in order
223 for us to make more rapid progress is to make the electron microscope
224 100 times better."
225 
226 What are the most central and fundamental problems of biology today?
227 They are questions like: What is the sequence of bases in the DNA? What
228 happens when you have a mutation? How is the base order in the DNA
229 connected to the order of amino acids in the protein? What is the
230 structure of the RNA; is it single-chain or double-chain, and how is it
231 related in its order of bases to the DNA? What is the organization of
232 the microsomes? How are proteins synthesized? Where does the RNA go?
233 How does it sit? Where do the proteins sit? Where do the amino acids
234 go in? In photosynthesis, where is the chlorophyll; how is it arranged;
235 where are the carotenoids involved in this thing? What is the system of
236 the conversion of light into chemical energy?
237 
238 It is very easy to answer many of these fundamental biological questions;
239 you just look at the thing! You will see the order of bases in the
240 chain; you will see the structure of the microsome. Unfortunately, the
241 present microscope sees at a scale which is just a bit too crude. Make
242 the microscope one hundred times more powerful, and many problems of
243 biology would be made very much easier. I exaggerate, of course, but
244 the biologists would surely be very thankful to you – and they would
245 prefer that to the criticism that they should use more mathematics.
246 
247 The theory of chemical processes today is based on theoretical physics.
248 In this sense, physics supplies the foundation of chemistry. But
249 chemistry also has analysis. If you have a strange substance and you
250 want to know what it is, you go through a long and complicated process
251 of chemical analysis. You can analyze almost anything today, so I am a
252 little late with my idea. But if the physicists wanted to, they could
253 also dig under the chemists in the problem of chemical analysis. It would
254 be very easy to make an analysis of any complicated chemical substance;
255 all one would have to do would be to look at it and see where the atoms
256 are. The only trouble is that the electron microscope is one hundred times
257 too poor. (Later, I would like to ask the question: Can the physicists do
258 something about the third problem of chemistry – namely, synthesis? Is
259 there a physical way to synthesize any chemical substance?
260 
261 The reason the electron microscope is so poor is that the f- value of the
262 lenses is only 1 part to 1,000; you don't have a big enough numerical
263 aperture. And I know that there are theorems which prove that it is
264 impossible, with axially symmetrical stationary field lenses, to produce
265 an f-value any bigger than so and so; and therefore the resolving power
266 at the present time is at its theoretical maximum. But in every theorem
267 there are assumptions. Why must the field be axially symmetrical? Why must
268 the field be stationary? Can't we have pulsed electron beams in fields
269 moving up along with the electrons? Must the field be symmetrical? I put
270 this out as a challenge: Is there no way to make the electron microscope
271 more powerful?
272 
273 The marvelous biological system
274 
275 The biological example of writing information on a small scale has
276 inspired me to think of something that should be possible. Biology is not
277 simply writing information; it is doing something about it. A biological
278 system can be exceedingly small. Many of the cells are very tiny, but they
279 are very active; they manufacture various substances; they walk around;
280 they wiggle; and they do all kinds of marvelous things – all on a very
281 small scale. Also, they store information. Consider the possibility that
282 we too can make a thing very small which does what we want – that we
283 can manufacture an object that maneuvers at that level!
284 
285 There may even be an economic point to this business of making things very
286 small. Let me remind you of some of the problems of computing machines. In
287 computers we have to store an enormous amount of information. The kind
288 of writing that I was mentioning before, in which I had everything down
289 as a distribution of metal, is permanent. Much more interesting to a
290 computer is a way of writing, erasing, and writing something else. (This
291 is usually because we don't want to waste the material on which we have
292 just written. Yet if we could write it in a very small space, it wouldn't
293 make any difference; it could just be thrown away after it was read. It
294 doesn't cost very much for the material).
295 
296 Miniaturizing the computer
297 
298 I don't know how to do this on a small scale in a practical way, but I do
299 know that computing machines are very large; they fill rooms. Why can't
300 we make them very small, make them of little wires, little elements –
301 and by little, I mean little. For instance, the wires should be 10 or 100
302 atoms in diameter, and the circuits should be a few thousand angstroms
303 across. Everybody who has analyzed the logical theory of computers has
304 come to the conclusion that the possibilities of computers are very
305 interesting – if they could be made to be more complicated by several
306 orders of magnitude. If they had millions of times as many elements,
307 they could make judgments. They would have time to calculate what is
308 the best way to make the calculation that they are about to make. They
309 could select the method of analysis which, from their experience, is
310 better than the one that we would give to them. And in many other ways,
311 they would have new qualitative features.
312 
313 If I look at your face I immediately recognize that I have seen it
314 before. (Actually, my friends will say I have chosen an unfortunate
315 example here for the subject of this illustration. At least I recognize
316 that it is a man and not an apple.) Yet there is no machine which,
317 with that speed, can take a picture of a face and say even that it is
318 a man; and much less that it is the same man that you showed it before
319 – unless it is exactly the same picture. If the face is changed; if
320 I am closer to the face; if I am further from the face; if the light
321 changes – I recognize it anyway. Now, this little computer I carry
322 in my head is easily able to do that. The computers that we build are
323 not able to do that. The number of elements in this bone box of mine
324 are enormously greater than the number of elements in our "wonderful"
325 computers. But our mechanical computers are too big; the elements in
326 this box are microscopic. I want to make some that are sub-microscopic.
327 
328 If we wanted to make a computer that had all these marvelous extra
329 qualitative abilities, we would have to make it, perhaps, the size of
330 the Pentagon. This has several disadvantages. First, it requires too
331 much material; there may not be enough germanium in the world for all
332 the transistors which would have to be put into this enormous thing.
333 There is also the problem of heat generation and power consumption; TVA
334 would be needed to run the computer. But an even more practical difficulty
335 is that the computer would be limited to a certain speed. Because of its
336 large size, there is finite time required to get the information from one
337 place to another. The information cannot go any faster than the speed of
338 light – so, ultimately, when our computers get faster and faster and
339 more and more elaborate, we will have to make them smaller and smaller.
340 
341 But there is plenty of room to make them smaller. There is nothing that
342 I can see in the physical laws that says the computer elements cannot
343 be made enormously smaller than they are now. In fact, there may be
344 certain advantages.
345 
346 Miniaturization by evaporation
347 
348 How can we make such a device? What kind of manufacturing processes
349 would we use? One possibility we might consider, since we have talked
350 about writing by putting atoms down in a certain arrangement, would
351 be to evaporate the material, then evaporate the insulator next to it.
352 Then, for the next layer, evaporate another position of a wire, another
353 insulator, and so on. So, you simply evaporate until you have a block
354 of stuff which has the elements – coils and condensers, transistors
355 and so on – of exceedingly fine dimensions.
356 
357 But I would like to discuss, just for amusement, that there are other
358 possibilities. Why can't we manufacture these small computers somewhat
359 like we manufacture the big ones? Why can't we drill holes, cut things,
360 solder things, stamp things out, mold different shapes all at an
361 infinitesimal level? What are the limitations as to how small a thing
362 has to be before you can no longer mold it? How many times when you are
363 working on something frustratingly tiny like your wife's wrist watch,
364 have you said to yourself, "If I could only train an ant to do this!"
365 What I would like to suggest is the possibility of training an ant to
366 train a mite to do this. What are the possibilities of small but movable
367 machines? They may or may not be useful, but they surely would be fun
368 to make.
369 
370 Consider any machine – for example, an automobile – and ask about
371 the problems of making an infinitesimal machine like it. Suppose, in the
372 particular design of the automobile, we need a certain precision of the
373 parts; we need an accuracy, let's suppose, of 4/10,000 of an inch. If
374 things are more inaccurate than that in the shape of the cylinder and
375 so on, it isn't going to work very well. If I make the thing too small,
376 I have to worry about the size of the atoms; I can't make a circle out of
377 "balls" so to speak, if the circle is too small. So, if I make the error,
378 corresponding to 4/10,000 of an inch, correspond to an error of 10 atoms,
379 it turns out that I can reduce the dimensions of an automobile 4,000
380 times, approximately – so that it is 1 mm. across. Obviously, if you
381 redesign the car so that it would work with a much larger tolerance,
382 which is not at all impossible, then you could make a much smaller device.
383 
384 It is interesting to consider what the problems are in such small
385 machines. Firstly, with parts stressed to the same degree, the forces go
386 as the area you are reducing, so that things like weight and inertia are
387 of relatively no importance. The strength of material, in other words,
388 is very much greater in proportion. The stresses and expansion of the
389 flywheel from centrifugal force, for example, would be the same proportion
390 only if the rotational speed is increased in the same proportion as
391 we decrease the size. On the other hand, the metals that we use have a
392 grain structure, and this would be very annoying at small scale because
393 the material is not homogeneous. Plastics and glass and things of this
394 amorphous nature are very much more homogeneous, and so we would have
395 to make our machines out of such materials.
396 
397 There are problems associated with the electrical part of the system –
398 with the copper wires and the magnetic parts. The magnetic properties
399 on a very small scale are not the same as on a large scale; there is the
400 "domain" problem involved. A big magnet made of millions of domains can
401 only be made on a small scale with one domain. The electrical equipment
402 won't simply be scaled down; it has to be redesigned. But I can see no
403 reason why it can't be redesigned to work again.
404 
405 Problems of lubrication
406 
407 Lubrication involves some interesting points. The effective viscosity of
408 oil would be higher and higher in proportion as we went down (and if we
409 increase the speed as much as we can). If we don't increase the speed so
410 much, and change from oil to kerosene or some other fluid, the problem is
411 not so bad. But actually we may not have to lubricate at all! We have a
412 lot of extra force. Let the bearings run dry; they won't run hot because
413 the heat escapes away from such a small device very, very rapidly.
414 
415 This rapid heat loss would prevent the gasoline from exploding, so an
416 internal combustion engine is impossible. Other chemical reactions,
417 liberating energy when cold, can be used. Probably an external supply
418 of electrical power would be most convenient for such small machines.
419 
420 What would be the utility of such machines? Who knows? Of course, a small
421 automobile would only be useful for the mites to drive around in, and I
422 suppose our Christian interests don't go that far. However, we did note
423 the possibility of the manufacture of small elements for computers in
424 completely automatic factories, containing lathes and other machine tools
425 at the very small level. The small lathe would not have to be exactly like
426 our big lathe. I leave to your imagination the improvement of the design
427 to take full advantage of the properties of things on a small scale, and
428 in such a way that the fully automatic aspect would be easiest to manage.
429 
430 A friend of mine (Albert R. Hibbs) suggests a very interesting possibility
431 for relatively small machines. He says that, although it is a very
432 wild idea, it would be interesting in surgery if you could swallow the
433 surgeon. You put the mechanical surgeon inside the blood vessel and it
434 goes into the heart and "looks" around. (Of course the information has
435 to be fed out.) It finds out which valve is the faulty one and takes a
436 little knife and slices it out. Other small machines might be permanently
437 incorporated in the body to assist some inadequately-functioning organ.
438 
439 Now comes the interesting question: How do we make such a tiny
440 mechanism? I leave that to you. However, let me suggest one weird
441 possibility. You know, in the atomic energy plants they have materials
442 and machines that they can't handle directly because they have become
443 radioactive. To unscrew nuts and put on bolts and so on, they have a set
444 of master and slave hands, so that by operating a set of levers here,
445 you control the "hands" there, and can turn them this way and that so
446 you can handle things quite nicely.
447 
448 Most of these devices are actually made rather simply, in that there is
449 a particular cable, like a marionette string, that goes directly from
450 the controls to the "hands." But, of course, things also have been made
451 using servo motors, so that the connection between the one thing and the
452 other is electrical rather than mechanical. When you turn the levers,
453 they turn a servo motor, and it changes the electrical currents in the
454 wires, which repositions a motor at the other end.
455 
456 Now, I want to build much the same device – a master-slave system
457 which operates electrically. But I want the slaves to be made especially
458 carefully by modern large-scale machinists so that they are one-fourth
459 the scale of the "hands" that you ordinarily maneuver. So you have
460 a scheme by which you can do things at one- quarter scale anyway –
461 the little servo motors with little hands play with little nuts and
462 bolts; they drill little holes; they are four times smaller. Aha! So
463 I manufacture a quarter-size lathe; I manufacture quarter-size tools;
464 and I make, at the one-quarter scale, still another set of hands again
465 relatively one-quarter size! This is one-sixteenth size, from my point of
466 view. And after I finish doing this I wire directly from my large-scale
467 system, through transformers perhaps, to the one-sixteenth-size servo
468 motors. Thus I can now manipulate the one-sixteenth size hands.
469 
470 Well, you get the principle from there on. It is rather a difficult
471 program, but it is a possibility. You might say that one can go much
472 farther in one step than from one to four. Of course, this has all to be
473 designed very carefully and it is not necessary simply to make it like
474 hands. If you thought of it very carefully, you could probably arrive
475 at a much better system for doing such things.
476 
477 If you work through a pantograph, even today, you can get much more
478 than a factor of four in even one step. But you can't work directly
479 through a pantograph which makes a smaller pantograph which then makes
480 a smaller pantograph – because of the looseness of the holes and the
481 irregularities of construction. The end of the pantograph wiggles with
482 a relatively greater irregularity than the irregularity with which you
483 move your hands. In going down this scale, I would find the end of the
484 pantograph on the end of the pantograph on the end of the pantograph
485 shaking so badly that it wasn't doing anything sensible at all.
486 
487 At each stage, it is necessary to improve the precision of the
488 apparatus. If, for instance, having made a small lathe with a pantograph,
489 we find its lead screw irregular – more irregular than the large-scale
490 one – we could lap the lead screw against breakable nuts that you
491 can reverse in the usual way back and forth until this lead screw is,
492 at its scale, as accurate as our original lead screws, at our scale.
493 
494 We can make flats by rubbing unflat surfaces in triplicates together
495 – in three pairs – and the flats then become flatter than the thing
496 you started with. Thus, it is not impossible to improve precision on
497 a small scale by the correct operations. So, when we build this stuff,
498 it is necessary at each step to improve the accuracy of the equipment
499 by working for awhile down there, making accurate lead screws, Johansen
500 blocks, and all the other materials which we use in accurate machine
501 work at the higher level. We have to stop at each level and manufacture
502 all the stuff to go to the next level – a very long and very difficult
503 program. Perhaps you can figure a better way than that to get down to
504 small scale more rapidly.
505 
506 Yet, after all this, you have just got one little baby lathe four
507 thousand times smaller than usual. But we were thinking of making an
508 enormous computer, which we were going to build by drilling holes on
509 this lathe to make little washers for the computer. How many washers
510 can you manufacture on this one lathe?
511 
512 A hundred tiny hands
513 
514 When I make my first set of slave "hands" at one-fourth scale, I am
515 going to make ten sets. I make ten sets of "hands," and I wire them to
516 my original levers so they each do exactly the same thing at the same
517 time in parallel. Now, when I am making my new devices one-quarter again
518 as small, I let each one manufacture ten copies, so that I would have
519 a hundred "hands" at the 1/16th size.
520 
521 Where am I going to put the million lathes that I am going to have? Why,
522 there is nothing to it; the volume is much less than that of even one
523 full-scale lathe. For instance, if I made a billion little lathes, each
524 1/4000 of the scale of a regular lathe, there are plenty of materials
525 and space available because in the billion little ones there is less
526 than 2 percent of the materials in one big lathe.
527 
528 It doesn't cost anything for materials, you see. So I want to build a
529 billion tiny factories, models of each other, which are manufacturing
530 simultaneously, drilling holes, stamping parts, and so on.
531 
532 As we go down in size, there are a number of interesting problems that
533 arise. All things do not simply scale down in proportion. There is the
534 problem that materials stick together by the molecular (Van der Waals)
535 attractions. It would be like this: After you have made a part and
536 you unscrew the nut from a bolt, it isn't going to fall down because
537 the gravity isn't appreciable; it would even be hard to get it off the
538 bolt. It would be like those old movies of a man with his hands full of
539 molasses, trying to get rid of a glass of water. There will be several
540 problems of this nature that we will have to be ready to design for.
541 
542 Rearranging the atoms
543 
544 But I am not afraid to consider the final question as to whether,
545 ultimately – in the great future – we can arrange the atoms the
546 way we want; the very atoms, all the way down! What would happen if we
547 could arrange the atoms one by one the way we want them (within reason,
548 of course; you can't put them so that they are chemically unstable,
549 for example).
550 
551 Up to now, we have been content to dig in the ground to find minerals.
552 We heat them and we do things on a large scale with them, and we hope
553 to get a pure substance with just so much impurity, and so on. But we
554 must always accept some atomic arrangement that nature gives us. We
555 haven't got anything, say, with a "checkerboard" arrangement, with the
556 impurity atoms exactly arranged 1,000 angstroms apart, or in some other
557 particular pattern.
558 
559 What could we do with layered structures with just the right layers?
560 What would the properties of materials be if we could really arrange the
561 atoms the way we want them? They would be very interesting to investigate
562 theoretically. I can't see exactly what would happen, but I can hardly
563 doubt that when we have some control of the arrangement of things on a
564 small scale we will get an enormously greater range of possible properties
565 that substances can have, and of different things that we can do.
566 
567 Consider, for example, a piece of material in which we make little
568 coils and condensers (or their solid state analogs) 1,000 or 10,000
569 angstroms in a circuit, one right next to the other, over a large area,
570 with little antennas sticking out at the other end – a whole series
571 of circuits. Is it possible, for example, to emit light from a whole
572 set of antennas, like we emit radio waves from an organized set of
573 antennas to beam the radio programs to Europe? The same thing would be
574 to beam the light out in a definite direction with very high intensity.
575 (Perhaps such a beam is not very useful technically or economically.)
576 
577 I have thought about some of the problems of building electric circuits
578 on a small scale, and the problem of resistance is serious. If you build
579 a corresponding circuit on a small scale, its natural frequency goes up,
580 since the wave length goes down as the scale; but the skin depth only
581 decreases with the square root of the scale ratio, and so resistive
582 problems are of increasing difficulty. Possibly we can beat resistance
583 through the use of superconductivity if the frequency is not too high,
584 or by other tricks.
585 
586 Atoms in a small world
587 
588 When we get to the very, very small world – say circuits of seven
589 atoms – we have a lot of new things that would happen that represent
590 completely new opportunities for design. Atoms on a small scale behave
591 like nothing on a large scale, for they satisfy the laws of quantum
592 mechanics. So, as we go down and fiddle around with the atoms down
593 there, we are working with different laws, and we can expect to do
594 different things. We can manufacture in different ways. We can use, not
595 just circuits, but some system involving the quantized energy levels,
596 or the interactions of quantized spins, etc.
597 
598 Another thing we will notice is that, if we go down far enough, all of our
599 devices can be mass produced so that they are absolutely perfect copies
600 of one another. We cannot build two large machines so that the dimensions
601 are exactly the same. But if your machine is only 100 atoms high, you
602 only have to get it correct to one-half of one percent to make sure the
603 other machine is exactly the same size – namely, 100 atoms high!
604 
605 At the atomic level, we have new kinds of forces and new kinds of
606 possibilities, new kinds of effects. The problems of manufacture and
607 reproduction of materials will be quite different. I am, as I said,
608 inspired by the biological phenomena in which chemical forces are used
609 in a repetitious fashion to produce all kinds of weird effects (one of
610 which is the author).
611 
612 The principles of physics, as far as I can see, do not speak against the
613 possibility of maneuvering things atom by atom. It is not an attempt
614 to violate any laws; it is something, in principle, that can be done;
615 but in practice, it has not been done because we are too big.
616 
617 Ultimately, we can do chemical synthesis. A chemist comes to us and says,
618 "Look, I want a molecule that has the atoms arranged thus and so; make
619 me that molecule." The chemist does a mysterious thing when he wants to
620 make a molecule. He sees that it has got that ring, so he mixes this
621 and that, and he shakes it, and he fiddles around. And, at the end of
622 a difficult process, he usually does succeed in synthesizing what he
623 wants. By the time I get my devices working, so that we can do it by
624 physics, he will have figured out how to synthesize absolutely anything,
625 so that this will really be useless.
626 
627 But it is interesting that it would be, in principle, possible (I think)
628 for a physicist to synthesize any chemical substance that the chemist
629 writes down. Give the orders and the physicist synthesizes it. How? Put
630 the atoms down where the chemist says, and so you make the substance. The
631 problems of chemistry and biology can be greatly helped if our ability to
632 see what we are doing, and to do things on an atomic level, is ultimately
633 developed – a development which I think cannot be avoided.
634 
635 Now, you might say, "Who should do this and why should they do it?"
636 Well, I pointed out a few of the economic applications, but I know that
637 the reason that you would do it might be just for fun. But have some
638 fun! Let's have a competition between laboratories. Let one laboratory
639 make a tiny motor which it sends to another lab which sends it back with
640 a thing that fits inside the shaft of the first motor.
641 
642 High school competition
643 
644 Just for the fun of it, and in order to get kids interested in this field,
645 I would propose that someone who has some contact with the high schools
646 think of making some kind of high school competition. After all, we
647 haven't even started in this field, and even the kids can write smaller
648 than has ever been written before. They could have competition in high
649 schools. The Los Angeles high school could send a pin to the Venice
650 high school on which it says, "How's this?" They get the pin back,
651 and in the dot of the 'i' it says, "Not so hot."
652 
653 Perhaps this doesn't excite you to do it, and only economics will do
654 so. Then I want to do something; but I can't do it at the present moment,
655 because I haven't prepared the ground. It is my intention to offer a
656 prize of $1,000 to the first guy who can take the information on the
657 page of a book and put it on an area 1/25,000 smaller in linear scale
658 in such manner that it can be read by an electron microscope.
659 
660 And I want to offer another prize – if I can figure out how to phrase
661 it so that I don't get into a mess of arguments about definitions – of
662 another $1,000 to the first guy who makes an operating electric motor –
663 a rotating electric motor which can be controlled from the outside and,
664 not counting the lead-in wires, is only 1/64 inch cube.
665 
666 I do not expect that such prizes will have to wait very long for
667 claimants.
668