因国内一些愚蠢的观念，理查德·费恩曼教授在国内不受推崇，知名度也不太高，虽然他在国际上是一位很出色的物理学家。他富有责任感，为人诙谐幽默，充满活力，遇到不好的事就会直接指出，而不是像国内学术界——绕来绕去四十分钟，其间充满自命清高，耍老资格，故弄玄虚，废话连篇，严重缺少实用内容……一提他们就气不打一处来。当初就因为这些原因，我把自己的志向从科学家改为科技商人，因为实在不愿与国内这种无聊透顶的家伙们为伍。费恩曼教授是我最喜欢的科学家之一。
___________________________________________
An Invitation to Enter a New Field of Physics
by Richard P. Feynman
This transcript of the classic talk that Richard Feynman gave on
December 29th 1959 at the annual meeting of the American
Physical Society at the California Institute
of Technology (Caltech) was first published in the February 1960 issue of
Caltech's Engineering
and Science, which owns the copyright. It has been made available on
the web at http://www.zyvex.com/nanotech/feynman.html
with their kind permission.
Information on the Feynman Prizes
Links to pages on Feynman
For an account of the talk and how people reacted to it,
see chapter 4 of Nano! by Ed Regis, Little/Brown 1995.
An excellent technical introduction to nanotechnology is
Nanosystems: molecular machinery, manufacturing, and computation
by K. Eric Drexler, Wiley 1992.
I imagine experimental physicists must often look with envy at
men like Kamerlingh Onnes, who discovered a field like low
temperature, which seems to be bottomless and in which one can go
down and down. Such a man is then a leader and has some
temporary monopoly in a scientific adventure. Percy Bridgman, in
designing a way to obtain higher pressures, opened up another new
field and was able to move into it and to lead us all along. The
development of ever higher vacuum was a continuing development
of the same kind.
I would like to describe a field, in which little has been done,
but in which an enormous amount can be done in principle. This
field is not quite the same as the others in that it will not tell us
much of fundamental physics (in the sense of, ``What are the strange
particles?'') but it is more like solid-state physics in the sense that it
might tell us much of great interest about the strange phenomena
that occur in complex situations. Furthermore, a point that is most
important is that it would have an enormous number of technical
applications.
What I want to talk about is the problem of manipulating and
controlling things on a small scale.
As soon as I mention this, people tell me about miniaturization,
and how far it has progressed today. They tell me about electric
motors that are the size of the nail on your small finger. And there is
a device on the market, they tell me, by which you can write the
Lord's Prayer on the head of a pin. But that's nothing; that's the most
primitive, halting step in the direction I intend to discuss. It is a
staggeringly small world that is below. In the year 2000, when they
look back at this age, they will wonder why it was not until the year
1960 that anybody began seriously to move in this direction.
Why cannot we write the entire 24 volumes of the Encyclopedia
Brittanica on the head of a pin?
Let's see what would be involved. The head of a pin is a
sixteenth of an inch across. If you magnify it by 25,000 diameters,
the area of the head of the pin is then equal to the area of all the
pages of the Encyclopaedia Brittanica. Therefore, all it is necessary to
do is to reduce in size all the writing in the Encyclopaedia by 25,000
times. Is that possible? The resolving power of the eye is about
1/120 of an inch---that is roughly the diameter of one of the little
dots on the fine half-tone reproductions in the Encyclopaedia. This,
when you demagnify it by 25,000 times, is still 80 angstroms in
diameter---32 atoms across, in an ordinary metal. In other words,
one of those dots still would contain in its area 1,000 atoms. So, each
dot can easily be adjusted in size as required by the photoengraving,
and there is no question that there is enough room on the head of a
pin to put all of the Encyclopaedia Brittanica.
Furthermore, it can be read if it is so written. Let's imagine
that it is written in raised letters of metal; that is, where the black is
in the Encyclopedia, we have raised letters of metal that are actually
1/25,000 of their ordinary size. How would we read it?
If we had something written in such a way, we could read it
using techniques in common use today. (They will undoubtedly find
a better way when we do actually have it written, but to make my
point conservatively I shall just take techniques we know today.)
We would press the metal into a plastic material and make a mold of
it, then peel the plastic off very carefully, evaporate silica into the
plastic to get a very thin film, then shadow it by evaporating gold at
an angle against the silica so that all the little letters will appear
clearly, dissolve the plastic away from the silica film, and then look
through it with an electron microscope!
There is no question that if the thing were reduced by 25,000
times in the form of raised letters on the pin, it would be easy for us
to read it today. Furthermore; there is no question that we would
find it easy to make copies of the master; we would just need to
press the same metal plate again into plastic and we would have
another copy.
How do we write small?
The next question is: How do we
write it? We have no
standard technique to do this now. But let me argue that it is not as
difficult as it first appears to be. We can reverse the lenses of the
electron microscope in order to demagnify as well as magnify. A
source of ions, sent through the microscope lenses in reverse, could
be focused to a very small spot. We could write with that spot like
we write in a TV cathode ray oscilloscope, by going across in lines,
and having an adjustment which determines the amount of material
which is going to be deposited as we scan in lines.
This method might be very slow because of space charge
limitations. There will be more rapid methods. We could first make,
perhaps by some photo process, a screen which has holes in it in the
form of the letters. Then we would strike an arc behind the holes
and draw metallic ions through the holes; then we could again use
our system of lenses and make a small image in the form of ions,
which would deposit the metal on the pin.
A simpler way might be this (though I am not sure it would
work): We take light and, through an optical microscope running
backwards, we focus it onto a very small photoelectric screen. Then
electrons come away from the screen where the light is shining.
These electrons are focused down in size by the electron microscope
lenses to impinge directly upon the surface of the metal. Will such a
beam etch away the metal if it is run long enough? I don't know. If
it doesn't work for a metal surface, it must be possible to find some
surface with which to coat the original pin so that, where the
electrons bombard, a change is made which we could recognize later.
There is no intensity problem in these devices---not what you
are used to in magnification, where you have to take a few electrons
and spread them over a bigger and bigger screen; it is just the
opposite. The light which we get from a page is concentrated onto a
very small area so it is very intense. The few electrons which come
from the photoelectric screen are demagnified down to a very tiny
area so that, again, they are very intense. I don't know why this
hasn't been done yet!
That's the Encyclopaedia Brittanica on the head of a pin, but
let's consider all the books in the world. The Library of Congress has
approximately 9 million volumes; the British Museum Library has 5
million volumes; there are also 5 million volumes in the National
Library in France. Undoubtedly there are duplications, so let us say
that there are some 24 million volumes of interest in the world.
What would happen if I print all this down at the scale we
have been discussing? How much space would it take? It would
take, of course, the area of about a million pinheads because, instead
of there being just the 24 volumes of the Encyclopaedia, there are 24
million volumes. The million pinheads can be put in a square of a
thousand pins on a side, or an area of about 3 square yards. That is
to say, the silica replica with the paper-thin backing of plastic, with
which we have made the copies, with all this information, is on an
area of approximately the size of 35 pages of the Encyclopaedia.
That is about half as many pages as there are in this magazine. All of
the information which all of mankind has every recorded in books
can be carried around in a pamphlet in your hand---and not written
in code, but a simple reproduction of the original pictures,
engravings, and everything else on a small scale without loss of
resolution.
What would our librarian at Caltech say, as she runs all over
from one building to another, if I tell her that, ten years from now,
all of the information that she is struggling to keep track of---
120,000 volumes, stacked from the floor to the ceiling, drawers full
of cards, storage rooms full of the older books---can be kept on just
one library card! When the University of Brazil, for example, finds
that their library is burned, we can send them a copy of every book
in our library by striking off a copy from the master plate in a few
hours and mailing it in an envelope no bigger or heavier than any
other ordinary air mail letter.
Now, the name of this talk is ``There is Plenty of Room at the
Bottom''---not just ``There is Room at the Bottom.'' What I have
demonstrated is that there is room---that you can decrease the size
of things in a practical way. I now want to show that there is plenty
of room. I will not now discuss how we are going to do it, but only
what is possible in principle---in other words, what is possible
according to the laws of physics. I am not inventing anti-gravity,
which is possible someday only if the laws are not what we think. I
am telling you what could be done if the laws are what we think; we
are not doing it simply because we haven't yet gotten around to it.
Information on a small scale
Suppose that, instead of trying to reproduce the pictures and
all the information directly in its present form, we write only the
information content in a code of dots and dashes, or something like
that, to represent the various letters. Each letter represents six or
seven ``bits'' of information; that is, you need only about six or seven
dots or dashes for each letter. Now, instead of writing everything, as
I did before, on the
surface of the head of a pin, I am going to use the
interior of the material as well.
Let us represent a dot by a small spot of one metal, the next
dash, by an adjacent spot of another metal, and so on. Suppose, to be
conservative, that a bit of information is going to require a little cube
of atoms 5 times 5 times 5---that is 125 atoms. Perhaps we need a
hundred and some odd atoms to make sure that the information is
not lost through diffusion, or through some other process.
I have estimated how many letters there are in the
Encyclopaedia, and I have assumed that each of my 24 million books
is as big as an Encyclopaedia volume, and have calculated, then, how
many bits of information there are (10^15). For each bit I allow 100
atoms. And it turns out that all of the information that man has
carefully accumulated in all the books in the world can be written in
this form in a cube of material one two-hundredth of an inch wide---
which is the barest piece of dust that can be made out by the human
eye. So there is plenty of room at the bottom! Don't tell me about
microfilm!
This fact---that enormous amounts of information can be
carried in an exceedingly small space---is, of course, well known to
the biologists, and resolves the mystery which existed before we
understood all this clearly, of how it could be that, in the tiniest cell,
all of the information for the organization of a complex creature such
as ourselves can be stored. All this information---whether we have
brown eyes, or whether we think at all, or that in the embryo the
jawbone should first develop with a little hole in the side so that
later a nerve can grow through it---all this information is contained
in a very tiny fraction of the cell in the form of long-chain DNA
molecules in which approximately 50 atoms are used for one bit of
information about the cell.
Better electron microscopes
If I have written in a code, with 5 times 5 times 5 atoms to a
bit, the question is: How could I read it today? The electron
microscope is not quite good enough, with the greatest care and
effort, it can only resolve
about 10 angstroms. I would like to try
and impress upon you while I am talking about all of these things on
a small scale, the importance of improving the electron microscope
by a hundred times. It is not impossible; it is not against the laws of
diffraction of the electron. The wave length of the electron in such a
microscope is only 1/20 of an angstrom. So it should be possible to
see the individual atoms. What good would it be to see individual
atoms distinctly?
We have friends in other fields---in biology, for instance. We
physicists often look at them and say, ``You know the reason you
fellows are making so little progress?'' (Actually I don't know any
field where they are making more rapid progress than they are in
biology today.) ``You should use more mathematics, like we do.''
They could answer us---but they're polite, so I'll answer for them:
``What you should do in order for us to make more rapid progress is
to make the electron microscope 100 times better.''
What are the most central and fundamental problems of
biology today? They are questions like: What is the sequence of
bases in the DNA? What happens when you have a mutation? How
is the base order in the DNA connected to the order of amino acids in
the protein? What is the structure of the RNA; is it single-chain or
double-chain, and how is it related in its order of bases to the DNA?
What is the organization of the microsomes? How are proteins
synthesized? Where does the RNA go? How does it sit? Where do
the proteins sit? Where do the amino acids go in? In
photosynthesis, where is the chlorophyll; how is it arranged; where
are the carotenoids involved in this thing? What is the system of the
conversion of light into chemical energy?
It is very easy to answer many of these fundamental biological
questions; you just look at the thing! You will see the order of bases
in the chain; you will see the structure of the microsome.
Unfortunately, the present microscope sees at a scale which is just a
bit too crude. Make the microscope one hundred times more
powerful, and many problems of biology would be made very much
easier. I exaggerate, of course, but the biologists would surely be
very thankful to you---and they would prefer that to the criticism
that they should use more mathematics.
The theory of chemical processes today is based on theoretical
physics. In this sense, physics supplies the foundation of chemistry.
But chemistry also has analysis. If you have a strange substance and
you want to know what it is, you go through a long and complicated
process of chemical analysis. You can analyze almost anything today,
so I am a little late with my idea. But if the physicists wanted to,
they could also dig under the chemists in the problem of chemical
analysis. It would be very easy to make an analysis of any
complicated chemical substance; all one would have to do would be
to look at it and see where the atoms are. The only trouble is that
the electron microscope is one hundred times too poor. (Later, I
would like to ask the question: Can the physicists do something
about the third problem of chemistry---namely, synthesis? Is there
a physical way to synthesize any chemical substance?
The reason the electron microscope is so poor is that the f-
value of the lenses is only 1 part to 1,000; you don't have a big
enough numerical aperture. And I know that there are theorems
which prove that it is impossible, with axially symmetrical
stationary field lenses, to produce an f-value any bigger than so and
so; and therefore the resolving power at the present time is at its
theoretical maximum. But in every theorem there are assumptions.
Why must the field be symmetrical? I put this out as a challenge: Is
there no way to make the electron microscope more powerful?
The marvelous biological system
The biological example of writing information on a small scale
has inspired me to think of something that should be possible.
Biology is not simply writing information; it is
doing something about
it. A biological system can be exceedingly small. Many of the cells
are very tiny, but they are very active; they manufacture various
substances; they walk around; they wiggle; and they do all kinds of
marvelous things---all on a very small scale. Also, they store
information. Consider the possibility that we too can make a thing
very small which does what we want---that we can manufacture an
object that maneuvers at that level!
There may even be an economic point to this business of
making things very small. Let me remind you of some of the
problems of computing machines. In computers we have to store an
enormous amount of information. The kind of writing that I was
mentioning before, in which I had everything down as a distribution
of metal, is permanent. Much more interesting to a computer is a
way of writing, erasing, and writing something else. (This is usually
because we don't want to waste the material on which we have just
written. Yet if we could write it in a very small space, it wouldn't
make any difference; it could just be thrown away after it was read.
It doesn't cost very much for the material).
Miniaturizing the computer
I don't know how to do this on a small scale in a practical way,
but I do know that computing machines are very large; they fill
rooms. Why can't we make them very small, make them of little
wires, little elements---and by little, I mean
little.
For instance, the
wires should be 10 or 100 atoms in diameter, and the circuits should
be a few thousand angstroms across. Everybody who has analyzed
the logical theory of computers has come to the conclusion that the
possibilities of computers are very interesting---if they could be
made to be more complicated by several orders of magnitude. If
they had millions of times as many elements, they could make
judgments. They would have time to calculate what is the best way
to make the calculation that they are about to make. They could
select the method of analysis which, from their experience, is better
than the one that we would give to them. And in many other ways,
they would have new qualitative features.
If I look at your face I immediately recognize that I have seen
it before. (Actually, my friends will say I have chosen an
unfortunate example here for the subject of this illustration. At least
I recognize that it is a man and not an apple.) Yet there is no
machine which, with that speed, can take a picture of a face and say
even that it is a man; and much less that it is the same man that you
showed it before---unless it is exactly the same picture. If the face
is changed; if I am closer to the face; if I am further from the face; if
the light changes---I recognize it anyway. Now, this little computer I
carry in my head is easily able to do that. The computers that we
build are not able to do that. The number of elements in this bone
box of mine are enormously greater than the number of elements in
our ``wonderful'' computers. But our mechanical computers are too
big; the elements in this box are microscopic. I want to make some
that are submicroscopic.
If we wanted to make a computer that had all these marvelous
extra qualitative abilities, we would have to make it, perhaps, the
size of the Pentagon. This has several disadvantages. First, it
requires too much material; there may not be enough germanium in
the world for all the transistors which would have to be put into this
enormous thing. There is also the problem of heat generation and
power consumption; TVA would be needed to run the computer. But
an even more practical difficulty is that the computer would be
limited to a certain speed. Because of its large size, there is finite
time required to get the information from one place to another. The
information cannot go any faster than the speed of light---so,
ultimately, when our computers get faster and faster and more and
more elaborate, we will have to make them smaller and smaller.
But there is plenty of room to make them smaller. There is
nothing that I can see in the physical laws that says the computer
elements cannot be made enormously smaller than they are now. In
fact, there may be certain advantages.
Miniaturization by evaporation
How can we make such a device? What kind of manufacturing
processes would we use? One possibility we might consider, since we
have talked about writing by putting atoms down in a certain
arrangement, would be to evaporate the material, then evaporate the
insulator next to it. Then, for the next layer, evaporate another
position of a wire, another insulator, and so on. So, you simply
evaporate until you have a block of stuff which has the elements---
coils and condensers, transistors and so on---of exceedingly fine
dimensions.
But I would like to discuss, just for amusement, that there are
other possibilities. Why can't we manufacture these small computers
somewhat like we manufacture the big ones? Why can't we drill
holes, cut things, solder things, stamp things out, mold different
shapes all at an infinitesimal level? What are the limitations as to
how small a thing has to be before you can no longer mold it? How
many times when you are working on something frustratingly tiny
like your wife's wrist watch, have you said to yourself, ``If I could
only train an ant to do this!'' What I would like to suggest is the
possibility of training an ant to train a mite to do this. What are the
possibilities of small but movable machines? They may or may not
be useful, but they surely would be fun to make.
Consider any machine---for example, an automobile---and ask
about the problems of making an infinitesimal machine like it.
Suppose, in the particular design of the automobile, we need a
certain precision of the parts; we need an accuracy, let's suppose, of
4/10,000 of an inch. If things are more inaccurate than that in the
shape of the cylinder and so on, it isn't going to work very well. If I
make the thing too small, I have to worry about the size of the
atoms; I can't make a circle of ``balls'' so to speak, if the circle is too
small. So, if I make the error, corresponding to 4/10,000 of an inch,
correspond to an error of 10 atoms, it turns out that I can reduce the
dimensions of an automobile 4,000 times, approximately---so that it
is 1 mm. across. Obviously, if you redesign the car so that it would
work with a much larger tolerance, which is not at all impossible,
then you could make a much smaller device.
It is interesting to consider what the problems are in such
small machines. Firstly, with parts stressed to the same degree, the
forces go as the area you are reducing, so that things like weight and
inertia are of relatively no importance. The strength of material, in
other words, is very much greater in proportion. The stresses and
expansion of the flywheel from centrifugal force, for example, would
be the same proportion only if the rotational speed is increased in
the same proportion as we decrease the size. On the other hand, the
metals that we use have a grain structure, and this would be very
annoying at small scale because the material is not homogeneous.
Plastics and glass and things of this amorphous nature are very much
more homogeneous, and so we would have to make our machines out
of such materials.
There are problems associated with the electrical part of the
system---with the copper wires and the magnetic parts. The
magnetic properties on a very small scale are not the same as on a
large scale; there is the ``domain'' problem involved. A big magnet
made of millions of domains can only be made on a small scale with
one domain. The electrical equipment won't simply be scaled down;
it has to be redesigned. But I can see no reason why it can't be
redesigned to work again.
Problems of lubrication
Lubrication involves some interesting points. The effective
viscosity of oil would be higher and higher in proportion as we went
down (and if we increase the speed as much as we can). If we don't
increase the speed so much, and change from oil to kerosene or some
other fluid, the problem is not so bad. But actually we may not have
to lubricate at all! We have a lot of extra force. Let the bearings run
dry; they won't run hot because the heat escapes away from such a
small device very, very rapidly.
This rapid heat loss would prevent the gasoline from exploding,
so an internal combustion engine is impossible. Other chemical
reactions, liberating energy when cold, can be used. Probably an
external supply of electrical power would be most convenient for
such small machines.
What would be the utility of such machines? Who knows? Of
course, a small automobile would only be useful for the mites to
drive around in, and I suppose our Christian interests don't go that
far. However, we did note the possibility of the manufacture of small
elements for computers in completely automatic factories, containing
lathes and other machine tools at the very small level. The small
lathe would not have to be exactly like our big lathe. I leave to your
imagination the improvement of the design to take full advantage of
the properties of things on a small scale, and in such a way that the
fully automatic aspect would be easiest to manage.
A friend of mine (Albert R. Hibbs) suggests a very interesting
possibility for relatively small machines. He says that, although it is
a very wild idea, it would be interesting in surgery if you could
swallow the surgeon. You put the mechanical surgeon inside the
blood vessel and it goes into the heart and ``looks'' around. (Of
course the information has to be fed out.) It finds out which valve is
the faulty one and takes a little knife and slices it out. Other small
machines might be permanently incorporated in the body to assist
some inadequately-functioning organ.
Now comes the interesting question: How do we make such a
tiny mechanism? I leave that to you. However, let me suggest one
weird possibility. You know, in the atomic energy plants they have
materials and machines that they can't handle directly because they
have become radioactive. To unscrew nuts and put on bolts and so on,
they have a set of master and slave hands, so that by operating a set
of levers here, you control the ``hands'' there, and can turn them this
way and that so you can handle things quite nicely.
Most of these devices are actually made rather simply, in that
there is a particular cable, like a marionette string, that goes
directly from the controls to the ``hands.'' But, of course, things also
have been made using servo motors, so that the connection between
the one thing and the other is electrical rather than mechanical.
When you turn the levers, they turn a servo motor, and it changes
the electrical currents in the wires, which repositions a motor at the
other end.
Now, I want to build much the same device---a master-slave
system which operates electrically. But I want the slaves to be made
especially carefully by modern large-scale machinists so that they
are one-fourth the scale of the ``hands'' that you ordinarily
maneuver. So you have a scheme by which you can do things at one-
quarter scale anyway---the little servo motors with little hands play
with little nuts and bolts; they drill little holes; they are four times
smaller. Aha! So I manufacture a quarter-size lathe; I manufacture
quarter-size tools; and I make, at the one-quarter scale, still another
set of hands again relatively one-quarter size! This is one-sixteenth
size, from my point of view. And after I finish doing this I wire
directly from my large-scale system, through transformers perhaps,
to the one-sixteenth-size servo motors. Thus I can now manipulate
the one-sixteenth size hands.
Well, you get the principle from there on. It is rather a
difficult program, but it is a possibility. You might say that one can
go much farther in one step than from one to four. Of course, this
has all to be designed very carefully and it is not necessary simply to
make it like hands. If you thought of it very carefully, you could
probably arrive at a much better system for doing such things.
If you work through a pantograph, even today, you can get
much more than a factor of four in even one step. But you can't
work directly through a pantograph which makes a smaller
pantograph which then makes a smaller pantograph---because of the
looseness of the holes and the irregularities of construction. The end
of the pantograph wiggles with a relatively greater irregularity than
the irregularity with which you move your hands. In going down
this scale, I would find the end of the pantograph on the end of the
pantograph on the end of the pantograph shaking so badly that it
wasn't doing anything sensible at all.
At each stage, it is necessary to improve the precision of the
apparatus. If, for instance, having made a small lathe with a
pantograph, we find its lead screw irregular---more irregular than
the large-scale one---we could lap the lead screw against breakable
nuts that you can reverse in the usual way back and forth until this
lead screw is, at its scale, as accurate as our original lead screws, at
our scale.
We can make flats by rubbing unflat surfaces in triplicates
together---in three pairs---and the flats then become flatter than the
thing you started with. Thus, it is not impossible to improve
precision on a small scale by the correct operations. So, when we
build this stuff, it is necessary at each step to improve the accuracy
of the equipment by working for awhile down there, making
accurate lead screws, Johansen blocks, and all the other materials
which we use in accurate machine work at the higher level. We have
to stop at each level and manufacture all the stuff to go to the next
level---a very long and very difficult program. Perhaps you can
figure a better way than that to get down to small scale more
rapidly.
Yet, after all this, you have just got one little baby lathe four
thousand times smaller than usual. But we were thinking of making
an enormous computer, which we were going to build by drilling
holes on this lathe to make little washers for the computer. How
many washers can you manufacture on this one lathe?
A hundred tiny hands
When I make my first set of slave ``hands'' at one-fourth scale,
I am going to make ten sets. I make ten sets of ``hands,'' and I wire
them to my original levers so they each do exactly the same thing at
the same time in parallel. Now, when I am making my new devices
one-quarter again as small, I let each one manufacture ten copies, so
that I would have a hundred ``hands'' at the 1/16th size.
Where am I going to put the million lathes that I am going to
have? Why, there is nothing to it; the volume is much less than that
of even one full-scale lathe. For instance, if I made a billion little
lathes, each 1/4000 of the scale of a regular lathe, there are plenty of
materials and space available because in the billion little ones there
is less than 2 percent of the materials in one big lathe.
It doesn't cost anything for materials, you see. So I want to
build a billion tiny factories, models of each other, which are
manufacturing simultaneously, drilling holes, stamping parts, and so
on.
As we go down in size, there are a number of interesting
problems that arise. All things do not simply scale down in
proportion. There is the problem that materials stick together by the
molecular (Van der Waals) attractions. It would be like this: After
you have made a part and you unscrew the nut from a bolt, it isn't
going to fall down because the gravity isn't appreciable; it would
even be hard to get it off the bolt. It would be like those old movies
of a man with his hands full of molasses, trying to get rid of a glass of
water. There will be several problems of this nature that we will
have to be ready to design for.
Rearranging the atoms
But I am not afraid to consider the final question as to whether,
ultimately---in the great future---we can arrange the atoms the way
we want; the very
atoms, all the way down! What would happen if
we could arrange the atoms one by one the way we want them
(within reason, of course; you can't put them so that they are
chemically unstable, for example).
Up to now, we have been content to dig in the ground to find
minerals. We heat them and we do things on a large scale with them,
and we hope to get a pure substance with just so much impurity, and
so on. But we must always accept some atomic arrangement that
nature gives us. We haven't got anything, say, with a
``checkerboard'' arrangement, with the impurity atoms exactly
arranged 1,000 angstroms apart, or in some other particular pattern.
What could we do with layered structures with just the right
layers? What would the properties of materials be if we could really
arrange the atoms the way we want them? They would be very
interesting to investigate theoretically. I can't see exactly what
would happen, but I can hardly doubt that when we have some
control of the arrangement of things on a small scale we will get an
enormously greater range of possible properties that substances can
have, and of different things that we can do.
Consider, for example, a piece of material in which we make
little coils and condensers (or their solid state analogs) 1,000 or
10,000 angstroms in a circuit, one right next to the other, over a large
area, with little antennas sticking out at the other end---a whole
series of circuits. Is it possible, for example, to emit light from a
whole set of antennas, like we emit radio waves from an organized
set of antennas to beam the radio programs to Europe? The same
thing would be to beam the light out in a definite direction with very
high intensity. (Perhaps such a beam is not very useful technically
or economically.)
I have thought about some of the problems of building electric
circuits on a small scale, and the problem of resistance is serious. If
you build a corresponding circuit on a small scale, its natural
frequency goes up, since the wave length goes down as the scale; but
the skin depth only decreases with the square root of the scale ratio,
and so resistive problems are of increasing difficulty. Possibly we
can beat resistance through the use of superconductivity if the
frequency is not too high, or by other tricks.
Atoms in a small world
When we get to the very, very small world---say circuits of
seven atoms---we have a lot of new things that would happen that
represent completely new opportunities for design. Atoms on a
small scale behave like
nothing on a large scale, for they satisfy the
laws of quantum mechanics. So, as we go down and fiddle around
with the atoms down there, we are working with different laws, and
we can expect to do different things. We can manufacture in
different ways. We can use, not just circuits, but some system
involving the quantized energy levels, or the interactions of
quantized spins, etc.
Another thing we will notice is that, if we go down far enough,
all of our devices can be mass produced so that they are absolutely
perfect copies of one another. We cannot build two large machines
so that the dimensions are exactly the same. But if your machine is
only 100 atoms high, you only have to get it correct to one-half of
one percent to make sure the other machine is exactly the same
size---namely, 100 atoms high!
At the atomic level, we have new kinds of forces and new
kinds of possibilities, new kinds of effects. The problems of
manufacture and reproduction of materials will be quite different. I
am, as I said, inspired by the biological phenomena in which
chemical forces are used in repetitious fashion to produce all kinds of
weird effects (one of which is the author).
The principles of physics, as far as I can see, do not speak
against the possibility of maneuvering things atom by atom. It is not
an attempt to violate any laws; it is something, in principle, that can
be done; but in practice, it has not been done because we are too big.
Ultimately, we can do chemical synthesis. A chemist comes to
us and says, ``Look, I want a molecule that has the atoms arranged
thus and so; make me that molecule.'' The chemist does a mysterious
thing when he wants to make a molecule. He sees that it has got that
ring, so he mixes this and that, and he shakes it, and he fiddles
around. And, at the end of a difficult process, he usually does
succeed in synthesizing what he wants. By the time I get my devices
working, so that we can do it by physics, he will have figured out
how to synthesize absolutely anything, so that this will really be
useless.
But it is interesting that it would be, in principle, possible (I
think) for a physicist to synthesize any chemical substance that the
chemist writes down. Give the orders and the physicist synthesizes
it. How? Put the atoms down where the chemist says, and so you
make the substance. The problems of chemistry and biology can be
greatly helped if our ability to see what we are doing, and to do
things on an atomic level, is ultimately developed---a development
which I think cannot be avoided.
Now, you might say, ``Who should do this and why should they
do it?'' Well, I pointed out a few of the economic applications, but I
know that the reason that you would do it might be just for fun. But
have some fun! Let's have a competition between laboratories. Let
one laboratory make a tiny motor which it sends to another lab
which sends it back with a thing that fits inside the shaft of the first
motor.
High school competition
Just for the fun of it, and in order to get kids interested in this
field, I would propose that someone who has some contact with the
high schools think of making some kind of high school competition.
After all, we haven't even started in this field, and even the kids can
write smaller than has ever been written before. They could have
competition in high schools. The Los Angeles high school could send
a pin to the Venice high school on which it says, ``How's this?'' They
get the pin back, and in the dot of the ``i'' it says, ``Not so hot.''
Perhaps this doesn't excite you to do it, and only economics will
do so. Then I want to do something; but I can't do it at the present
moment, because I haven't prepared the ground. It is my intention
to offer a prize of $1,000 to the first guy who can take the
information on the page of a book and put it on an area 1/25,000
smaller in linear scale in such manner that it can be read by an
electron microscope.
And I want to offer another prize---if I can figure out how to
phrase it so that I don't get into a mess of arguments about
definitions---of another $1,000 to the first guy who makes an
operating electric motor---a rotating electric motor which can be
controlled from the outside and, not counting the lead-in wires, is
only 1/64 inch cube.
I do not expect that such prizes will have to wait very long for claimants.
