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There's Plenty of Room at the Bottom
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
Caltech Engineering and Science, Volume 23:5, February 1960, pp 22-36.
__________________________________________________________________
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 Encyclopaedia 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 ever
recorded in books can be carried around in a pamphlet in your hand –
and not written in code, but as 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
x 5 x 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 x 5 x 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 axially symmetrical? Why must
the field be stationary? Can't we have pulsed electron beams in fields
moving up along with the electrons? 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 sub-microscopic.
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 out 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 a 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.