From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Sun Jun 15 2003 - 17:18:44 MDT
On Sun, 15 Jun 2003, Kevin Freels wrote:
> If we had a computer with sufficient processing power,
> couldn't we have simulation software that could tell us pretty much
> every chemical compound/material that could be made?
There are three aspects of this question:
a) Can you design the molecule?
b) Can you determine its properties?
c) Can you actually assemble one of them?
The answers are probably something like;
a) Probably not, you cannot design every possible molecule, there are
just too many possibilities. Drexler (Nanosystems, pg 264) computes
that the number of possible atomic configurations in even a small
1 nm^3 volume, limiting yourself to only 30 atom times is 10^148.
That is a *huge* number. I'm not sure even an MBrain could touch it.
b) To determine its properties you (unless you do it from a "theory"
perspective you have to do a molecular simulation. Molecular
simulations EAT computer time because you have to run them at
something between femtosecond and picosecond time resolution.
I also don't think physicists and chemists have a good handle
on predicting physical properties yet -- quantum dots come to mind.
c) There will likely be physical chemical (molecular) designs which
there is no way to assemble.
> This would eleminate the trial and error approach and solve possible
> every disease!
However, "combinatorial chemistry" does work at small scales and does
generate a *lot* of nanoscale molecules -- many hundreds of thousands to
perhaps millions of combinations. And in fact Francis Collins et al (the
director of NHGRI and associates), in a recent Nature paper discussing
where does genomic/proteomic research go next actually suggested using
combinatorial chemistry to pre-screen for molecules that interact with
defective or maladapted proteins, particularly for rare disease gene
candidates, to speed up the development of candidates for treating the
disease. (So you are thinking along the right lines...)
> I estimated that there are so many possible chemicals out there in nature
> that we could probably never get to a point where we could try them all
> on everything.
The phase space of chemicals at the nanoscale is *very* large -- though
certainly Nature is complex -- it hasn't even begun to touch the
surface.
Interesting question though.
Robert
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