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RICHARD P. FEYNMAN - HERE IN 1981
There's Plenty of Room at the Bottom
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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
Britannica 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 Britannica. 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 Britannica.
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 Britannica 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
twohundredth 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.
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