There is Plenty of Room at the Bottom
Richard Feynman（1959）
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
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
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 Venice
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.
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