November 21, 2018 at 4:18 pm #6697Ciprian BeguParticipant
In one of your first blog posts, you say that: “The central dogma in modern chemistry is that it can be reduced to the study of atoms, which are described using quantum theory. Since quantum equations cannot be accurately solved for any molecule that has more than a couple of subatomic particles, the dogma has hindered the development of a theory of reactions. Chemists use a wide variety of intuitions in chemical understanding but hardly any predictive laws exist.“
Could you please elaborate more on the point underlined? Everyone that has done Chemical experiments in the lab in high school for instance could be under the impression that everything happening in that lab is based on a very thorough understanding of molecules. But what is not seen in the lab, in terms of prediction? Also, what methods — if not predictive laws — are the chemical and pharmaceutical industries using to synthesize so many substances?
And, more broadly, what is the limit of our current understanding of chemistry?December 2, 2018 at 8:31 am #6712Ashish DalelaKeymaster
There are many problems of prediction in chemistry but the basic issue is that chemicals do not always produce a reaction. The “yield” of chemical experiments varies based on temperature, pressure, and sometimes the yield is so low that we have to add catalysts to improve the yield. So one can ask: if two chemicals are present why don’t they always react? Also, can one say which molecules will react to produce a chemical reaction? The short answer is that we cannot predict which molecules will react. We can say on aggregate that some molecules will react, and if we want more of them to react then we will have to find the conditions (such as a higher or lower temperature and pressure) or even inject catalysts to improve the rate of reaction.
So the reactants are the possibility of a chemical reaction but not the reality of a reaction. The conversion of possibility into a reality requires many additional factors, and generally, no condition guarantees a 100% reaction completion. Therefore, one large part of modern chemistry is how to improve the “yield” of reactions by improving the probability of a reaction.
Within the human body chemicals don’t automatically react, but need catalysts which are called enzymes. Many of the proteins transcribed from the DNA are enzymes and they catalyze the reactions. Therefore, simply by controlling the rate of enzyme production one can change the rate of the chemical reaction. The enzyme production is controlled by the hormones and these hormones are controlled by a variety of other things including mental/emotional states. The DNA transcription is also controlled by epigenetic factors which are changed by the environment.
So, at a very low level, it appears that chemistry is deterministic if we assume that the reaction involves some chemical reactants. But if you look at a slightly bigger picture, then you need enzymes. Looking at a slightly bigger picture, these enzymes are controlled by the production of hormones in the body which change with the mental state. And the production of these hormones is then influenced by epigenetic factors or our environmental conditioning.
So there are many levels of control in the body and the causal prediction becomes weaker and weaker as we rise higher up in the causal chain because we have to take more and more factors into account in order to explain the incidence of a chemical reaction. Owing to this fact, the simple picture of the body is that there are chemical reactions, but a more complex picture is that these chemical reactions are influenced by our mental and emotional state, the history of this mental and emotional state, and even the inherited mental and emotional state of our parents. Therefore, we cannot formulate a simple physical picture of the reaction.
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