The ultimate Babbage machine was described by K Eric Drexler in his 1987 book "Engines of Creation". This was a "rod logic" device about the size of a bacterium, and Drexler talks about it here: http://www.halcyon.com/nanojbl/NanoConProc/nanocon2.html

to give you an idea of where Drexler thought this could go:

> 10. Computers from Molecular Mechanical Components
These computing devices are smaller than the transistors that were commonly in use in computers a couple of years ago by a factor of 104 in linear dimension, which means 1012 in volume. Thus a device of the capability of a single chip microprocessor, like the Z80 or Motorola 68000 made with 3 micron technology, could be put into a volume of 1/1000th of a cubic micron.

>For random access memory, you should get nanosecond access times with 5 cubic nanometers per bit, or allowing for overhead, a density of about 1020 bits per cubic centimeter. That's more information in a cubic centimeter than people have written down since they started making marks on papyrus.

>Tape memory gives you another factor of 100 in memory density. Bits would be stored by the presence of a bulky or less bulky side group on a polymer chain, such as polyethylene. To read the tape, you would mechanically probe it to find out how bulky the side group was. The write operation would involve chemical transformation. A reasonable length for such a tape is several microns; a reasonable spooling speed is like a meter per second. To get from one end of the tape to the other is thus a matter of microseconds. We're talking here about tape systems that are far faster than present day hard drives.

>Estimates of power dissipation are relatively fuzzy. Making a gigahertz clock assumption and assuming a dissipation of 50kT per bit of a 32-bit word per cycle, we're talking of power dissipation in nanowatts. For a single device in good thermal contact with its environment that's a temperature rise of less than a thousandth of a degree Kelvin.

>Thus a large computer can be small on the scale of a mammalian cell, giving some plausibility if you also assume some other hardware and a lot of software development, to the notion of cell repair systems. Also, yesterday I estimated the computational capacity that you could get in one cubic centimeter using this crude mechanical technology - more computational power in a desk top than exists in the world today.

>There are a number of papers that discuss this and related topics. If you write to the Foresight Institute [Box 61058, Palo Alto, CA 94306] and send \$5, you can get a packet of papers that describes these things in more technical detail. For a donation of \$25, you can subscribe to the Foresight Institute newsletter "Foresight Update."

[For more up-to-date information, see the Foresight Institute home page. See also Chapter 12 of Nanosystems.]


So if you have the technology to make wormholes, I suspect making bacterium sized supercomputers wouldn't be a really big deal either. If such a device can be made "self aware" is a different question altogether.