Archive for the ‘My Ideas’ Category

Science vs. Religion?

November 25, 2009

Science does not seem to have a firm position on miracles. There are lots of different ways scientists can legitimately look at miracles and explanations that depend on miracles.

Each of these progressions starts from statements that seem clearly true, and shades gradually into gray areas. At what point, in these slippery slopes, would you draw the line?
1) It is the job of a scientist to…

… try to understand how things would work if there were no miracles involved.

… assume that what they are studying does not involve miracles.

… assume that the natural world works entirely without miracles.

… disbelieve in miracles.

2) It is the job of a scientist to…

… increase the world’s stock of scientific knowledge.

… educate people about science.

… promote awareness of scientific explanations of things.

… promote belief in non-miraculous explanations for things.

… promote unbelief in miracles.

3) The theory of evolution is fundamental to biology, and…

… a non-miraculous explanation for life’s diversity.

… an adequate theory to replace the previous, miraculous explanation.

… a theory that should replace the previous, miraculous explanation.

… a theory that proves God did not create the species.

4) Therefore, scientists should…

… try to educate people about evolution.

… try to convince people that evolution is the best theory we have.

… directly attack creationist (miraculous) explanations


Digital Copies Needed

November 10, 2009

Reading Darwin gets my own brain working, and I’ve been thinking about the necessity of accurate copying in lifelike self-replicators.

While googling Stuart Kauffman, I came across a concept of “Lipid World” which proposes that life arose by the development of lipid vesicles. Lipids can self-assemble into cell-like enclosures with lipid bilayer walls. This is highly suggestive. But the Lipid World FAQ points out that lipid vesicles “give rise to somewhat imperfect copies of themselves” and concludes that “Life then moved on an axis of increasing FIDELITY rather than increasing complexity.”

It seems to me that in any given environment, it will either be the case that a large proportion of possible structures are “fit” – that is, self-sustaining through stability and/or replication – or only a few possible structures are “fit.”

If a large proportion of possible structures are fit, then those structures will arise easily, and each spontaneously appearing structure will evolve (without even needing replication) to a very fit state; then they will persist in that state, acting as an energy sink that precludes further advances and probably precludes the development of self-replication. Note that this is not intended as a description of life as we know it; rather, it is a description of non-living “natural processes.”

If only a small proportion of possible structures are fit, then any given accumulation of random variation from a fit structure is likely to be unfit. Thus, in a population reproducing by imperfect copying, the population’s fitness will tend to devolve.

Therefore, self-replicators, from the start, must have been based around a high-fidelity copying process – indeed, a digital copying process. Covalent chemistry is digital. If I understand correctly, lipid vesicle copying is not digital, even though it can transmit information.

To put this theory into concrete terms, it seems to me that the Lipid World would quickly converge to a sea of optimal vesicles, and then improvement would stop. These vesicles would be as “natural” and as non-living as clay particles. Either vesicles or clay particles might then have provided a substrate for the development of self-templating covalent polymers.

Since covalent chemistry is digital, self-replicating polymers would be able to explore thin and perilous pathways in the space of all possible molecules. As long as a sufficient number of “offspring” were identical to the parents, an arbitrarily large fraction of the variants could be less fit; competition would remove the less fit ones, and preserve the good-enough ones until the rare improvement came along.

For another writeup of this theory from a slightly different point of view, see my post on the origins of life on my “Responsible Nanotechnology” blog.