One of the themes I have persisted with in these posts is that in chemistry, thinking about theory is either dead or in terminal decline. Prove me wrong!
 
In my last post, I offered a challenge to readers, specifically, can you provide answers to:
1.     Why did nature choose ribose for nucleic acids?
2.     How did homochirality arise?
So far, I have no guesses/inspired answers. Come on! Assuming someone is actually reading these posts, either they don't care or it is too difficult. Now, surely you are not going to concede that I can work out more than you can? So, is anyone going to try?
 
My first answer next week.

As I haven't updated for some time, there should be a lot of references summarized, however, many of them turned out to be only of partial interest. There were a few papers discussing the origin of chondrules. Up until recently, while the formation of these had been something of a mystery, the nearest there was to a conclusion was that they were formed in the plume formed by collisions of planetesimals. Fu et al. (Science 346: 1089 – 1092) found that chondrules in one meteorite formed at about 2 – 3 My after the first small bodies. This was supported by Palme, et al. (Earth Planet. Sci. Lett. 411: 11 – 19.) who found that chondrules behaved as if they were formed before any larger bodies, and were not formed by impacts. On the other hand, Johnson et al. (Science 517: 339 – 341) argued that chondrules in CB chondrites probably formed in a plume produce by an impact at a relative velocity of greater than 10 kilometers per second. If so, meteorites are a byproduct of planet formation rather than left-over building material. Of course there may have been more than one route that lead to their formation, but as can be seen, there is no clear answer to this question yet.
 
The landing on the Jupiter family comet 67P/Churyumov-Gerasimenko probably attracted as much recent public interest as anything in science, and some data are coming in. Examination of the comet's water (Altweg et al. Science 347: 126952-1 to 3) showed that the comet had a D/H ratio that is three times greater than Earth's water, and hence Jupiter family comets could not be a significant source of Earth's water. The reason this is important is that the water has to come from somewhere, and comets were once considered the obvious source. However, the usual distant comets were found to have too much deuterium, so Jupiter-family comets became the choice. The alternative is carbonaceous chondrites, but the problem with these is they are rather rare, and lie on the outer part of the asteroid belt. Had they been the source, why were there so many of them, and so few of what are now the more common asteroids? And if there were that many, why did they not accrete into a small planet? In my theory, neither comets nor chondrites are significant sources of water on earth.
 
 Meanwhile, spectral data of the surface of the comet was compatible with the presence of opaque minerals associated with non-volatile organic material with C-H and O-H bonds, but with very little contribution from N-H bonds (Capaccioni et al. 2015. Science aaao628 – 1 to 5.). There may have been small amounts of ice, but no ice-rich patches and the surface was generally dehydrated. Similarly, (Hassig et al. 2015 Science 347: aaa0276-1 to 4) showed the outgassing comprised water, CO and CO₂. The relevance here is the absence of significant amounts of nitrogen-containing compounds, as required by my theory of planetary formation, as long as the body did originate in the Jovian region. That is pleasant support, even though the supporters do not realize it.
 
Significant results are beginning to come in from Gale crater, on Mars. Of particular interest to me was that from Bridges et al. 2015 (J. Geophys. Res.: Planets: 10.1002/2014JE004757). The clays found at Gale crater was consistent with the basalt having reacted with a fluid of pH between 7.5 and 12, and further, the reactions did not occur in a setting where exchange with an overlying CO₂ atmosphere was possible because had it been so, there would have been deposits of carbonates, and there were not. My theory involved an early methane atmosphere with ammonia in the local water, although of course Gale crater may not be a good example of early Mars, as impact craters could have their own localized geology. Nevertheless, overall all these facts are in accord with what I published, and nothing has been found that contradicts it, so I am tolerably happy.
 
On a more personal level, on March 4 I have been asked by the Wellington Astronomical Society to give a talk, and include some chemistry. Accordingly, I chose "Origin of life" as a topic and have put out an abstract and issued two challenges, which readers here may as well join in.
1.     Why did nature choose ribose for nucleic acids?
2.     How did homochirality arise?
Put your guesses or inspired knowledgeable comments at the end of this post. The answers are not that difficult, but they are subtle. I shall post my answers in due course. In the meantime, I am offering serious discounts on my ebook "Planetary Formation and Biogenesis" from Amazon (US and UK only) from March 6 for about six days, the discount abating over time, so get in early. (Sorry about that commercial intrusion.)

Yes, this post will be controversial, but I am doing it for several reasons. The first is my wife was convinced there is, and she was equally convinced that I, as a scientist, would quietly argue the concept was ridiculous. However, as she was dying of metastatic cancer we had a discussion of this issue, and I believe the following theory gave her considerable comfort. Accordingly, I announced this at her recent funeral in case it helped anyone else, and I have received a number of requests to post the argument. I am doing two posts: this one with some mathematics, and one where I merely assert the argument for those who want a simpler account.
 
First, is there any evidence at all? The issue is complicated in that observational verification can only be answered by dying. If there is, you find out. What we have to rely on is statements from people who did not quite die, and there are numerous accounts from such people \, and they claim to see a tunnel of light, and relations at the other end. There are two possible explanations:
(1)  What they see is true,
(2)   When the brain shuts down, it produces these illusions.
The problem with (2) is, why does it do it the same way for all? There was also an account recently of someone who died on an operating table, but was resuscitated, and he then gave an account of what the surgeons were doing as viewed from above. One can take this however one likes, but it is certainly weird.
 
What I told Claire arises from my interpretation of quantum mechanics, which is significantly different from most others', and I shall give a brief outline now. If anyone is interested in going deeper, I have an ebook on the subject (http://www.amazon.com/dp/B00GTB8LJ6) I start by considering the two-slit experiment, and consider the diffraction pattern that is obtainable. Either there is a wave guiding the particles or there is not. Most physicists argue there is not. They just happen to give that distribution. You ask, why? They tend to say, "Shut up and compute!" For the fact is, computations based on what is a wave equation give remarkably good agreement with observation, but nobody can find evidence for the empty wave. For me, there must be something causing this behaviour. Accordingly, my first premise is:
The wave-like distributions found in quantal experiments are caused by a wave. (1)
This was first proposed in de Broglie's pilot wave theory, but modern quantum theory does not assert this.
 
As with general quantum mechanics, the wave is represented mathematically by
 ψ = Aexp(2πiS/h)    (2)
where A is the amplitude, S is the action, and h is Planck's quantum of action. Note that the exponent must be a number. As a consequence, it is generally held that the wave function is complex, but this is not entirely true. From Euler's relation
exp(πi) =-1         (3)
it follows that, momentarily, when S = h/2, or h, the wave becomes real.
My second premise is
The physics of the system are determined when the wave becomes real.   (4)
This is the first major difference between my interpretation and standard quantum mechanics. The concept that the system may behave differently when the wave function is real rather than imaginary has, as far as I know, not been investigated. This has a rather unexpected benefit too: the dynamics involve a number of discrete "realizations", and the function is NOT smooth and continuous in our domain. If you accept that, it immediately follows why stationary states of atoms are stable and the electron does not radiate when it accelerates as required by Maxwell's laws. The reason is, the position of realization does not change in the stationary state, and therefore the determination of the properties shows no acceleration. From that, it is very simple to derive both the Uncertainty Principle and the Exclusion Principle, and these are no longer independent propositions.
 
Now, if (1) and (4), it follows that the wave front must travel at the same velocity as the particle; if it did not, how could it affect the particle? The phase velocity of the wave is given by
v = E/p        (5)
Since p is the momentum of the particle, and if the phase velocity is the same as the particle velocity (for the particle, consider expectation velocity), then the right hand side must be mv²/mv = v. (Recall that the term v must equal the article velocity.) That means the energy of the system must be twice the kinetic energy of the particle. This simply asserts that the wave transmits energy. Actually, every other wave in physics transmits energy; just not the textbook quantal matter wave, which transmits nothing, it does not exist, but it defines probabilities. (As an aside, since energy is proportional to mass, and mass is proportional to probability of finding it, in general this interpretation does not conflict directly with standard quantum mechanics.) There are obvious consequences of this that lie outside this post, but what I find strange is that nobody else seems to have considered this option. For this discussion, the most important consequence is that both particle and wave must maintain the same energy. The wave sets the particle energy because the wave is deterministic; the particle is not and has to be guided by the wave. There is now a further major difference between this interpretation and the standard interpretation: waves are both linear and separable, as in standard wave physics. There is no need for a non-divisible wave for the total state of an assembly because there is no renormalization due to probabilities.
 
Now, what is consciousness? Strictly speaking, we do not know exactly, but examination of brains that are conscious appear to show considerable electrical activity. Furthermore, this activity is highly ordered. While writing this, my brain is not sending random pulses, but rather it is organising some reasonably complicated  thoughts and setting out action. To do that, and overcome entropy, there is a serious expenditure of energy in the body. (The brain uses a remarkably high fraction of the body's energy.) I leave aside how this happens, but I require consciousness to be due to some matrix that remains undefined but evolves and is superimposed on the brain, and it orders the activity. Without such a superimposed entity, simple entropy considerations would lead to the decay of the order required for conscious thought. Such order must involve the movement of electrons an since this is quantum controlled, then the corresponding energy must be found in an associated wave. It therefore follows that when we are conscious and living "here", there is a matrix of waves with corresponding energy "there".
 
Accordingly, if this Guidance Wave interpretation of quantum mechanics is correct, then the condition for life after death is very simple: death occurs because the body cannot supply the energy required to match the Guidance Waves that are organizing consciousness, but if at that point the energy within the Guidance Wave matrix can dissociate itself from the body, and maintain itself "there", and recall that the principle of linearity is that other waves do not affect it, then that wave package can continue, and since it represents the consciousness of a person, that consciousness continues. That does not mean there is life after death, but it does in principle appear to permit it.
 
Is the Guidance Wave interpretation correct? As far as I am aware, there is no observation that would falsify my alternative interpretation of quantum mechanics, while my Guidance Wave theory does make two experimental predictions that contradict standard quantum mechanics, and these could be tested in a reasonably sophisticated physics lab. It also greatly simplifies the calculation of some chemical bond properties.
 
Is there life after death? In my opinion, you only find out when you die, but interestingly, this interpretation gave Claire surprising comfort as her death approached. If it gives any comfort to anyone else, this post will be worth it to me.