Is science sometimes in danger of getting tunnel vision? Recently published ebook author, Ian Miller, looks at other possible theories arising from data that we think we understand. Can looking problems in a different light give scientists a different perspective?

Update On Planetary Accretion

You announce an alternative theory and further papers come forwards. There is a natural tenseness: are you falsified already? At the end of each month I shall report on progress of which I am aware, good, bad or indifferent. For April, the most relevant papers I came across were as follows.
 
Smith et al. (Science 336: 214-217): Mercury has a relatively high moment of inertia (0.353 + 0.014). Since a uniform sphere has a moment of inertia of 0.4, this indicates that Mercury has a relatively thin crust. What was postulated was a silicate crust ca 300 km thick, 100 km of iron sulphide, then an iron-rich liquid core, possibly over a solid interior core, all of which was claimed to be consistent with Mercury having considerably more reduced components, similar to those of enstatite chondrites. How does that sit? I made a prediction that Mercury would have more reduced components, and specified phosphides, nitrides and carbides, which are found in enstatite chondrites. A higher sulphide content for Mercury had previously been proposed, and I never considered a separate layer of iron sulphide because iron sulphide is usually considered to dissolve in an iron core.
 
Kleine et al. (Geochim. Cosmochim. Acta. 84: 186-203): a number of Angrites (a small but diverse group of refractory mafic to ultramafic meteorites from a body that had differentiated) were shown to have originated from one body and that body apparently differentiated twice, both within 2 My of the formation of calcium aluminium inclusions. Actual accretion of the parent body must have occurred within 1.5 My. This is harder to judge. I require the rocky planets other than Mercury to accrete between 1 and 2 My, with Mercury essentially complete after 1 My, although there would be numerous later crater-forming strikes. Since we do not know what the parent body was, standard theory might argue that it was one of the planetesimals, although standard theory has no mechanism by which planetesimals form; they are the assumed starting place.
 
Fastook et al. (Icarus 219: 25-40): evidence was found for subglacial meltwater channels in the south circumpolar Dorsa Argentea (Mars) dating from the Noachian/Hesperian. The authors state these data require a local temperature in the range of -50 to -75 oC, the data are consistent with basal melting but not "top-down" melting, and this contradicts the concept of a warm and wet early Mars. My explanations for the Martian fluvial systems assumed temperatures never averaged much above -60 oC, and were probably generally about -80 oC, which equally contradicts the early "warm and wet" Mars. I also provided a mechanism for basal melting to explain the great chaotic flows, and the same mechanism would apply here, except that the fluid could escape, hence the channels.
 
Yaoling Niu (RSC Advances 2: 3587-3591): Zr-Hf and Nb-Ta are effectively elemental twins in their standard valence states (+4 and +5 respectively), and standard theory argues they should not separate during geological processes. The assumption also is that the Earth has always been basically "oxidized", as shown by the distribution of vanadium and chromium in various ancient and modern magmas. As Niu shows, perhaps they should behave similarly, but seemingly they do not. My proposed mechanism for Earth's formation requires the original material to be reduced, more like enstatite chondrites. These pairs do not have equivalent redox potentials, and hence would behave differently under certain reduced conditions.
 
Readers will have to form their own opinion as to the relative success of the theory, but I feel that so far it is very much still alive.
Posted by Ian Miller on Apr 26, 2012 3:26 AM Europe/London

Share this |

Share to Facebook Share to Twitter Share to Linked More...

Leave a comment?

You must be signed in to leave a comment on MyRSC blogs.

Register free for an account at http://my.rsc.org/registration.