What are the physical limits on miniaturization?

[Sofaspud]

Let’s start off with the assumption that money is no object. We’re not talking Bill Gates rich; we’re talking Money Doesn’t Matter At All rich. I’m not interested in the economic or practical limits on miniaturizing technology; I’m simply curious about where the line is drawn past which we physically cannot go.

For example: if we were to scale down a car, preserving with meticulous obsession the interplay between each and every part – perhaps we assemble it one atom at a time, who cares? – how small can it become before physical limits imposed by nature prevent us from going smaller?

Radios: I seem to recall that an antenna needs to be a certain length to function at a given frequency. However, if we were to connect a ultra-mini-micro-nano radio to an antenna that is properly sized, how small could it go?

Is there a size limit at which a material (steel, for example) stops behaving like we expect? If that’s the case, our mini-car might blow up… bad news for Adam Ant joyriding around in it. But if materials behave the same at all sizes, then what’s to stop us from constructing invisible nano-Fords?

Again, who cares about practicality? I’m wondering simply about the physics of the thing.

[Jurph]

@Sofaspud

For example: if we were to scale down a car, preserving with meticulous obsession the interplay between each and every part – perhaps we assemble it one atom at a time, who cares? – how small can it become before physical limits imposed by nature prevent us from going smaller?

The challenge will be reproducing things like the car radio, the alternator, or the wires at super subscale. If you want to make a Model A, then your limit shrinks to the smallest practical chamber in which gasoline molecules can interact with oxygen molecules on a large enough scale that the statistical average of interactions is predictable. You’re probably going to need a few thousand (million?) gasoline molecules so that the macro effects are what you’d expect.

[muttrox]

I would think Richard Feynman’s comments on minituarization would get you a long way.
http://www.zyvex.com/nanotech/feynman.html

[muttrox]

…which I’m rereading right now. Lookie here.

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.

[gotpasswords]

@Sofaspud

Radios: I seem to recall that an antenna needs to be a certain length to function at a given frequency. However, if we were to connect a ultra-mini-micro-nano radio to an antenna that is properly sized, how small could it go?

Funny that you mention radio. From today’s news, comes a radio made of a single carbon nanotube.

[Sofaspud]

@muttrox

I would think Richard Feynman’s comments on minituarization would get you a long way.
Feynman's Talk

Ooh, Feynman! That’s good reading, thanks Muttrox! This is exactly the sort of thing I was thinking of, but my search skills were/are apparently very much lacking.

gotpasswords: cool! Thanks for the link.

Re: the overall idea, I got as far as thinking about the fuel-air mix needed and how small a combustion chamber might be and realized that I had no idea how the materials actually behaved, hence the question.

Of course, that led to thinking about miniaturization in general, hence my OP. These articles ought to go along way towards answering my questions. THanks!