In my last post of 2013, I gave a problem that provides part of the plot of my ebook novel Athene's Prophecy: how could a Roman prove the heliocentric theory? Before doing that, however, I have to go on a diversion to discuss how you actually prove a theory. Yes, I know, you usually see people write, you can never prove a scientific theory; all you can do is falsify it. That is actually wrong. Let us suppose you have a theory A that predicts the set of observations P if experiment E is carried out. Equally, we could have theory B that predicts the set of observations Q if experiment E is carried out. We carry out E and observe O. There are several possibilities: O can be an element of either P or Q, or of both, or of neither. If both, the experiment is irrelevant in terms of being definitive, if neither both theories are wrong, and if one but not the other, the other is wrong. Under this circumstance, no theory is proven. To prove a theory, it must be of the form, if and only if theory A is correct, then we shall see the set of observations P if experiment E is carried out. The problem, of course, is to justify the "only if" part, so that is what has to be done by my Roman to prove the heliocentric theory.
 
In practice, there is more to it. The first step to overturning a theory, which is what had to be done here, is to review the literature. Personally, I find classical science to be quite interesting because it shows some very interesting issues that apply today just as then, and further, if you look carefully, what we read today about the ancients is really not fair to them, and in the next series of posts, I hope to illustrate that point.
 
Now, there are two ways of reviewing the literature. The first is to read what is there, accept it, and try to work out how to develop what from it. I believe that is the common practice today and most scientists are quite happy to accept the literature explanations and use them to solve more puzzles, in the spirit of Kuhn's "normal science". The second way is to deeply question certain issues, to be sure the theory is on sound ground. In my opinion, this is done only too infrequently. How many current scientists have ever really questioned something of fundamental nature given by authority? Throughout history, everybody seems to think "they are on the right track". We know classical science was not, but how many think we are currently more or less correct? Quantum electrodynamics is regarded by many as the most accurate theory ever in science, but it can be regarded as a subset of quantum field theory. The vacuum energy predicted by quantum field theory appears to be wrong by a factor of at least 10^107. That is an enormous difference, in fact one could say it is well outside any experimental error! But how many scientists actually think quantum field theory might be wrong in some way? More importantly for you, how many theories or explanations in chemistry have you ever thought could be wrong? If the answer is more than zero, what did you do about it? Why not?
 
That last question gets to the heart of the matter: the reviewer has to have an urge to overturn something. The "official" line is, that urge is provided by observations that do not fit the theory, however I think that is wrong. The vacuum energy error mentioned above is an example. The fit with theory is appalling but there is no attempt to overthrow the theory because quantum electrodynamics makes some absolutely remarkably accurate predictions elsewhere. When the theory works much of the time, as Kuhn noted, awkward results tend to be placed in the drawer and forgotten. The average scientist does not wish to overturn the apple cart. The reason for not wishing to do this are clear: most of the time he believes he will not get anywhere, and spend a lot of time not getting there. Einstein spent over fifteen years trying to get relativity in order, and how many scientists have his ability? With promotions, funding and general standing in the scientific community at stake, who wants to spend years not getting anywhere, getting publications rejected, or being regarded as a curiosity? In classical times, the problem would have been worse because if you succeeded, who would care? People work for reward, and for most scientists, reward means, acknowledgement by your peers. You do not get that by trying to show they are wrong. In classical times, most of the time you had no peers. Archimedes made his discovery not to unravel nature, but to solve a problem given to him. There would be no reward for a Roman to prove the heliocentric theory, because current theory did everything that was required of it.
 
Finally, I promise I shall get to the issue, but not next post, because it is time for a review of planetary formation theory.

A Happy New Year to you all. In my last post of 2013, I gave a problem that provides part of the plot of my ebook novel Athene's Prophecy: how could a Roman prove the heliocentric theory? I shall give the answer in due course, but in the interim I commented on another post that I would start a discussion on how to get an idea so here goes. I should mention that I intend to follow the procedure of my first ebook, Elements of Theory 1, and the example I am going to use, that of the 2-norbornyl cation, had a chapter in that devoted to it, and I suggested an answer. The example has gone on through my chemical career: the non-classical carbenium ion.
 
What is the first step in having an idea? In my view, identifying a reason to have one. If you are satisfied that all is well, your brain will not devote time to the problem of what if it is not well. So, let me start on this non-classical ion. In Chemistry World (August, p 20, and January 2014, p 26) we see that a German group had isolated the ion and found that it was symmetrical. As Chemistry World put it, "Case closed!" Or is it? Recall that in "The Hitch-hiker's Guide to the Galaxy" the final answer was given, but what was the question? My first point is, if you accept the "Case Closed" situation, you will never have a contrary idea because you are not looking for one. The first step is to recognize you need it. This must be closely followed by the asking of questions of what you know.
 
The original question regarding the non-classical 2-norbornyl ion was clear: why did the exo 2-norbornyl derivatives solvolyse much more rapidly than the endo derivatives? Accordingly, the first question is, is this symmetrical ion pertinent to the original question? It is reasonably obvious that Chemistry World thinks so, but let us ask a further question:  if the activated state is the fully developed carbenium ion, then how does exo and endo give dramatically different rates of solvolysis, because the substituent is now lost? If the activated states for exo and endo derivatives are different (which they must be to get different reaction rates, unless our concept of reaction rates is entirely wrong), then in what way, and why? The why would appear easiest: in the activated state the anion has yet to fully leave. Another question: how can a species on an energy maximum be isolated and live long enough to have its nmr spectrum measured? The answer to that question, surely, is that the carbenium ion must be in an energy well, not at an energy maximum. If so, under standard activation theory, the energy maximum is before the fully developed ion forms, in accord with the previous conclusion that the anion is still present.
 
Thye next question is, was there any pertinent evidence to question whether the activated state was a partially developed symmetric ion? The answer is, yes there is. In the symmetric ion, C1 has an equal exposure to the positive charge, but Brown had shown by substitution that in the activated state there was no particular positive charge at that site, and that was his biggest point against the "non-classical ion". Now, back to the question, how to have an idea? The activated state is now defined as having the leaving group to have partially left. What does that mean? Surely there is a significant dipole between C2 and the leaving group, along the bond axis. The partial positive charge is located at C2, not at C1 (by substitution data) with C6 unclear at this point. The next question is, what mechanism can conceivably stabilize this system and not be available to the endo substituent? That requires you to think about all the possibilities available, and list them. There are not that many. The answer to that, in my view answers, the question, and the case is not closed by the existence of a symmetric ion, as previously claimed. That does not mean the determination of the symmetric ion is wrong, but rather that while it exists, it does not actually answer the original question.