Before Christmas, I raised the question, how could the ancients have proven the Earth goes around the sun? I guess it is about time to get started on answering it. The first task was to review the literature. It then becomes obvious that you have to overturn Aristotle. There are various places where one can start, but one is to decide why we have day and night. Let us use Aristotle’s own methodology, which is to break the issue down into discrete issues. Thus we say, either the Earth is fixed and everything rotates around it, or everything is more or less fixed, and the Earth rotates. Aristotle had reached that step, and had “proven” that the Earth did not rotate. Therefore the day/night must occur through the sun orbiting the Earth. The heliocentric theory, despite its advantages, is falsified.
 
At this point, we should examine the methodology of the experiment. It is important to recognize that Aristotle was very clear on one point, and he has been badly misrepresented on this ever since. Aristotle clearly asserted that logic must be applied to experimental observations, and that observation alone was critical. So, what was his experiment? Aristotle argued that if you threw a stone vertically into the air, it always came back to the same place. Had the earth been rotating, the path length of a rotation increased with height, in which case the stone should drag back westwards. It did not, so the earth did not rotate. Note that at this point, Aristotle was effectively arguing for the conservation of angular momentum, or even better, the principle of least action. I wonder how many of my readers would recognize that, and know why it is so significant? Before reading any further, what do you think about Aristotle’s experiment? What is wrong, and how would you correct it, bearing in mind you have only ancient technology?
 
In my ebook, Athene’s Prophecy, my protagonist dismisses the experiment by arguing that vertical is defined as the point where the stone falls back to the same place. By defining the point thus, if the stone does not come back to the same place, it was not thrown vertically. He then criticizes Aristotle by arguing that the correct way to do the experiment is to simply drop the stone from a high tower. The reason is that while Aristotle would be correct in that there should be a drag to the west going up, exactly the opposite should occur on the way back down. What should happen if dropped from a tower is that the stone would strike the ground slightly to the east of the vertical position, and in Rhodes, where this was being discussed, also slightly to the south. Can you see why?
 
What happened next is that my protagonist refused to carry out the experiment. This is a somewhat difficult experiment to carry out, but in my opinion, it might be of considerable interest to senior school students, and it introduces them to many of the issues of science that still apply. They need a high tower (or some equivalent), and the first problem is to define the exact vertical spot below it. This is difficult enough to do today with modern surveying equipment, but in those days, the error range is likely to exceed the effect. The school could set this up, with the help of external surveyors, or even physicists if they can find any. The students have to select the right material (a small lead cone, dropped point down without tumbling would probably be optimal) and correct for wind speed. This experiment, more than any other I can think of that is suitable for schools, introduces the concept of experimental error, and they can get illustrations of this because the experiment, in theory, besides proving the Earth rotates, with a little mathematics permits two measurements of the size of the Earth. The answers are likely to be hilarious, unfortunately, once the student confronts the issue of required accuracy. The problem is the difference between the height and the earth's radius, but it may give a new appreciation to the extreme requirements of the large hadron collider, where protons (look up their size) circle a 26 km loop and collide.

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? The short answer is, it was not possible for a Roman to do this directly from then current knowledge. This is a fine example of how you cannot get from A to B directly, but have to through some other places first. That would have been possible, but it did not happen. Why not? The question is of interest because it goes to the heart of what science is about, and that is a more difficult question to answer than you might think, because most scientists do not really have the time to consider it.
 
As an example, during my early working time in an institution, only too much was wasted writing proposals, trying to get funding, trying to keep funding, trying to get or get access to equipment, in other words, doing just about anything except science. Then when I was doing science, the most important thing was to get the material for another paper, because failure to produce enough papers meant failure with the funding, etc. What happened to me was exactly what Kuhn argued would happen: I always started a project that I thought had a very good chance of success.
 
So, back to the question of the title. The first problem would be, why bother? Aristotle was generally believed to be correct, and even if he were wrong in something, who cared? The important point was that the then current theory was splendidly capable of predicting everything of general interest, and, more to the point, it "proved" that the heliocentric theory was wrong. The Ptolemaic model was perfectly adequate for calculating and predicting the timing of things of astronomical, agricultural and religious interest. There was no apparent need to change it. This is where I disagree, because the problem lay in an incorrect understanding of dynamics. As a consequence, their wrong dynamics arguably inhibited progress. I believe that if you understand what is correct, you are more likely to make advances.
 
Aristarchus challenged the "fixed earth" model, but he was hardly rewarded well for what he did, and even now, how many people realize he made more progress than Copernicus? The real problem lay in the proof of the fixed earth model, which relied on experimental proof, in which the observations were interpreted in terms of Aristotle's dynamics, and these were just plain wrong, oddly enough because in getting to them, Aristotle abandoned his own methodology and relied on "the obvious".
 
What Galileo did was to show the "proof" was wrong, he undermined Aristotle's dynamics, and further, he showed the satellites of Jupiter did not fit at all well with the model of Claudius Ptolemy. However, telescopes were not available to my Roman, so he had some work to do. In my next post I shall look at the actual problem in more detail, but in the meantime, how many scientists even now ask themselves whether the conclusions they reach from their experiments could be wrong because the theory they assumed in reaching it could be wrong? Obviously much of our theory is very well tested, but is all of it? Our understanding of electromagnetism is almost certainly correct, so our instruments should give us the correct results, but if we go deeper into our chemical interpretations, how much is actually dependent on a hypothesis that is difficult to test?

This update covers two months and focuses on some compositional issues. Why is composition important? In my theory, initial accretion is driven by chemical interactions, hence material that accretes at different temperatures may have different compositions. The mechanism of initial accretion in standard theory is undefined, but is usually considered to be due to gravitational interactions, in which case there should be no compositional differences, apart from outer bodies being icy. Unfortunately, the following does not show much light on this issue.

One paper involved the formation of the Moon (Nature 504: 27 - 29) The problems here are reasonably simple. Collisional dynamics suggest that which is flung off Earth comprises mainly material from the impactor, and this should have different isotope compositions from Earth, since it appears that certain isotopes varied in relative concentration by some radial function of their location in the accretion disk. However, isotope evidence indicates both bodies came from the same source. Thus the oxygen, chromium, titanium, tungsten and silicon isotope compositions of the two bodies are indistinguishable, which suggests common origin. The answers to this usually invoke extra processes, such as extensive mixing or a later gravitational resonance with the sun, but the feasibility of any of these as explanations is unclear. There are differences in composition between the Earth and the Moon. The Moon has less than 10% iron, and is poorer in volatile elements. The collision theory explains the former in terms of the iron core of the impactor merging with the earth's core, while the lack of volatile elements is consistent with these being lost from a hot disk.  It appears that refractory elements have similar abundance in both bodies. Seemingly, either the Moon formed from material from Earth's mantle, or that the Moon and the silicate portion of Earth each formed from an identical mix. My explanation is that both formed at the same radial distance and hence formed the same way from the same material, the Moon having come from either one or two bodies that grew at the Lagrange positions L4 or L5, and were dislodged when they became too big to remain in those positions. That concept is not original, but my theory makes accretion of solid bodies much more probable at our solar distance. Further, a late-forming body at L4 or L5 would have less iron, because the body, and the outer part of Earth, would form from material that started further from the sun (because it is the last part of material moving inwards).

The second major set of publications was the collection of papers in vol 343 of Science relating to results from Curiosity in Gale Crater, Mars. These results have already been announced, and as far as theories of planetary formation are concerned, these were not very interesting. One point that was of interest was the evidence of water flow and of aqueous leaching. The rover found sedimentary rock, smectites (clays, both Fe and Al rich being present) and calcium sulphate that had been precipitated from water. The evidence is in excellent agreement with the theory put forward some years ago that when an impactor struck Mars and formed a crater, it would also heat the ground beneath it and liquefy any ice. Calculations indicated this could remain in the liquid state for perhaps thousands of years. The water at Gale Crater was estimated to have been liquid for a minimum time of hundreds to tens of thousands of years. Such a short time is consistent with this impact theory, but of course since the measurements were taken inside an impact crater, it may not be relevant to Mars in general.

Finally localized sources of water vapour were detected by far infrared spectroscopy on the Herschel Space Observatory on the dwarf planet (1) Ceres (Nature 505: 525 – 527). This water vapour appeared to have been emitted from localized mid-latitude sources. The cause of the water evaporation could not be determined, but it could be due to either comet-like sublimation or to cryo-volcanism. The amount of water on Ceres is of interest because it might indicate that Ceres did not originate in the asteroid belt. More will be known about Ceres when the Dawn space craft reaches it.

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.