Re: Moore's law

Dan Clemmensen (
Fri, 26 Jun 1998 22:08:13 -0400

Michael Nielsen wrote:
> Storing stuff in 3-d gives rise to a large dissipation problem.
> Heuristically, the problem is that the heat generated goes like length
> cubed (total number of components), while heat dissipated goes like
> length squared (proportional to the surface area). As I've stated
> elsewhere, the reversible compution solution to this problem has a large
> potential hurdle to overcome, in the form of heat generated by error
> correction, which suffers the same probelm re dissipation.
I was referring to storage density, not storage speed. Nanomechanical
storage systems should require no power unless bits are being read or
written, so power dissipation is a function of I/O speed. Three-dimensional
storage in a nonomechanical system, using 100 atoms per bit alllows
a fair number of extra atoms for "overhead" functions such as support
and heat-conduction. The energy dissipated to read or write a bit
nanomechanically should be very small compared to that needed by current
technology, and diamondoid should be able to operate at much higher
temperatures than silicon-based devices. Diamondoid is a much better conductor
of heat than silicon, also.

Reversable computation may be useful for logic functions, subject to the
problems you describe. As I understand it, it's not relevant for storage.