The question of how planets form continued to attract attention. Everyone agrees the accretion starting position is the disk of gas falling into the forming star. The gas also contains "dust", ranging in size from a colloidal dispersion to pieces a few millimetres in diameter. It is possible some pieces could be bigger, but we would not see them. The question then is, what happens next? The standard theory is that by some undefined mechanism, this accretes into planetesimals, which are about the size of asteroids, and the resultant distribution of these, which is smooth and continuous with regards to distance from the star, gravitationally collide. The asteroid belt is therefore likely to be the remnants of this process. In my opinion, that is wrong, and the first stages were driven by chemistry, and the distribution of growing bodies is highly enhanced in certain zones of temperature appropriate for the specific chemistry.
 
There was an interesting paper in Nature 511: 22-24  that surveyed problems with the standard theory of planetary formation, and ends with the question, "Why is our system so different from so many others?" Unfortunately, no answer was provided. As my theory shows, the reason is very simple: the admittedly limited evidence strongly suggests that our star cleaned out its accretion disk very quickly after formation, and this stopped accretion. Other systems kept going, which leads to more massive bodies and stronger gravitational interactions, and this results in what is effectively planetary billiards takes place. Unfortunately, once gravitational interactions get big enough, the resultant system becomes totally unpredictable.
 
Another interesting problem involved the question of rubble-pile asteroids. One major question is how rocky planets accrete, and the standard theory seems to assume that somehow moderate sized objects form, and gravity makes these come together, and as they get more rubble, they become bigger objects. Eventually they become big enough that they heat up, partly through radioactivity and partly through the loss of potential energy when bodies pile up, and the heated body starts to melt together. Asteroids are often believed to be piles of such rubble. However, two papers were published that make this proposition less likely. In this context, my theory requires rocky bodies accreted while the accretion disk is still present to be joined together chemically, and in the case of the asteroids, by cements similar to those used by the ancient Romans, and which also come from certain volcanoes such as Vesuvius. Such asteroids can still be piles of rubble, but cemented together where the surfaces meet. Effectively, they are very poorly compacted concretes. Also, non-cemented rubble piles would exist if the pieces came together following the disk clean-out.
 
The first (Nature 512: 174 – 176) involved asteroid (29075) 1950 DA, which has a density of 1.7 0.7. Since the solids are believed to be similar to enstatite chondrite, it should have a density of 3.55, hence it appears to have about 50% space inside it.  However, the rotational velocity is such that if it comprised rubble, the rubble should peel off. The authors argued that it must be held together with van der Waals forces from fine grains between the larger pieces. I have a problem with this. If the spaces are filled, then the density should be higher. Note that van der Waals forces are very weak at a very short range, and according to Feynman's calculations, they fall off inversely to the power of 6 with distance. The second paper (Icarus 241: 358 -372) analysed the size/frequency distribution of small asteroids and compared these with computed collision frequencies, and they found that the assumption of rubble-pile asteroids leads to a significant worse fit with observation than the assumption of monolithic bodies, hence they conclude that the majority of main-belt asteroids are monolithic.
 
Finally, there is the question of global magma oceans. The standard theory has rocky planets finally accreting through massive collisions, which lead to massive generation of heat, which in turn converts the rocky planet to magma. However, evidence has been presented (Earth Planet. Sci. Lett. 403: 225 – 235) that the geology of Mars is incompatible with this picture. My mechanism for planetary formation does not forbid a magma ocean, but unless there is a giant collision between two massive bodies, there will not be, and planets can form without one. In fact, they probably have to, because the energy of collision of massive bodies is generally such that size reduction occurs as material is shed to space.

An interesting problem is how should scientists present their information to the public. The issue is more complicated because we have to assume that some of the public will be educated enough to understand what is presented, and if there are flaws, to pick on them. The problem then is, as other members of the public see the fallout, science itself gets discredited. One piece of news that I saw was a statement that from analysis of the decay products of heavy isotopes ¹⁸²Hf and ¹²⁹I, the gas and dust that formed the solar system was present in a dust cloud isolated from interstellar space for 30 million years before collapse to form the solar system took place. The news item stated that this was quite remarkable, because it only took about 1 My for the star to form once it got going (or so we think) and about 30 My for the rocky planets to finally form (this is almost certainly wrong – Mars took about 3My.)  What would be your reaction to seeing that?
 
My initial reaction, knowing something about the subject, was to say, "Hold on a minute. We date the early stages of solar system formation through the decay of ²⁶Al, and that has a half-life of about 73,000 years." If we take the half-lives through 30 My, it becomes obvious that there is essentially no ²⁶Al left. As it happens, with what we know to have been present initially, there is insufficient left to be useful for dating after about 3My at best. So, how do we resolve this?
 
If we look at the actual paper, (Science 345: 650 – 653), what they actually say is that certain radioactive nuclei were formed 100 My and 30 My before the sun started forming. They then produce one of those "pretty pictures that implies just about everything important ended 30 My before star formation, and that is presumably what the writer of the public statement latched onto. This is not helped by the same being presented in an explanation (Science 345: 620-621) which states early on that the gas cloud was isolated for 30 My before stellar formation. However, at the end of the paper, the authors of the paper conceded that additional supernovae were required to put the ²⁶Al into the gas just before star formation. The problem is, such supernovae would also put in more of the other isotopes as well.
 
Thus the statement that the dust formed 30 My before star formation is just plain misleading. That does not mean it is wrong, and the authors have found something. The problem is, it has since been interpreted as something else by the media who do not have the skill to actually analyse what is there. So, what the story should have said is that the material used to form the solar system was a mix of material from a sequence of supernovae. The basic gas, hydrogen and helium, was, of course, there from the big bang.
 
This article could be written off as unimportant. The problem is, this sort of reporting is more widespread. Think of climate change. Why is there such a heated debate? Surely we can find some critical results and agree what they mean. Unfortunately, this does not seem to happen. I think that learned societies have a responsibility to present critical fact-stating documents, where everything within them is analysed and its reliability stated. Most topics have only a very limited number of really critical papers; the problem is to get these summarized so that the conclusion is not misleading.

One of the more unusual publications recently involved a theoretical computation of a hypothetical carbonium ion (or at least a very short-lived molecule-ion) C-(CH₃)₅ . (Angew. Chem. Int. Ed 53: 7875 – 7878.) Computations concluded that the structure was that of a trigonal bipyramid, which effectively had three methyl groups around the central carbon atom, which was in sp² configuration, and two other methyl groups bonded to the p orbital of the central carbon atom. All methyl groups were in sp³ configuration. The important point about such a computation is that the ion is argued to be sufficiently stable that it exists, albeit short-lived, as it has two computed decay modes. The question now is, is it right? The issue is important because it proposes a type of bonding that so far has not been recognized, or if it has, the recognition passed by me.
 
There is one important point to note. Computations indicate that the CH₅ ion does not follow the same structure. This ion can be considered as a distorted CH₃ system that bonds to a H₂ molecule. This gives three equivalent hydrogen atoms and two further equivalent, but different atoms. This is supported by the infrared spectrum (Science 309: 12219 – 1222) which shows a fluxional molecule consistent with that structure and with full hydrogen scrambling. Why does the replacement of hydrogen atoms with methyl groups make such a difference? Then again, does it?
 
The CH₅ ion is conceptually simple, in that it is really a carbenium ion making an electrophilic attack on a two-electron bond. Now, if it will do that to the hydrogen molecule bond, why does the same thing not happen with, say the (CH₃)₃ – C ion which could make an electrophilic attach on the C – C bond of ethane?
 
The next question is, does it matter? I think it does, because it calls into question a number of bond issues. The first is, where is the formal positive charge? In my view, it starts on the central carbon atom. I argued that the gas phase stabilities of the usual carbenium ions is given quite satisfactorily by assuming the positive charge is first located at the formal ion centre, and it then polarizes the substituents (Aust J. Chem. 26 : 301-310.) That makes the (CH₃)₃ – C ion considerably more stable than the CH₃ ion, and that ion would more readily polarize the bond in ethane. The issue then resolves itself to whether the formation of a two-electron C – C – C bond, plus the polarization energy is lower than the energy of the C – C bond in ethane, plus its polarization energy. A further question then is, is a two-electron C – C – C bond even possible? What we are asking, at least in conventional chemical thinking, is for the two methyl electrons that are separated over that distance to pair, and get the appropriate phase relationship. What disturbs me about this is that there are no other examples that I can think of where a vacant p orbital can bind two electrons in that way. My immediate thinking then makes me ask, is there any equivalent in boron chemistry? I am not sufficiently familiar to say there is not, but I am certainly unaware of any. Therefore the question is, does B-(CH₃)₅ exist? If the trigonal bipyramid structure for C-(CH₃)₅ is correct, one would think it should because the troublesome ionic character that leads to rearrangement is missing. If on the other hand, such an ion represents the (CH₃)₃ – C ion polarizing ethane, then there should be no B-(CH₃)₅.