2012 - neutrino chemistry chaos

Note: these articles have been published in InfoChem, the supliment to Education in Chemistry produced by The Royal Society of Chemistry.

2012 is a modern 1970's style classic disaster movie [1]. The movie scenario goes something like this; the energy process in the Sun are being effected by a very unusual planetary alignment. This has altered the Suns internal nuclear processes causing vast quantities of a new type of particle to be emitted, which on interaction with the Earth's core heats it up dramatically. This causes the Earth's tectonic plates to start to move rapidly causing vast earthquakes and tidal waves leading to unfolding chaos. In the film we see our heroes in a car (and later in a plane) speeding out of LA impossibly close to (but always just in front of) vast chasms splitting and swallowing up everything behind them! So how much, if any at all, does this agree with what we know about the science of the Earth and the nuclear chemistry going on in the Sun?

Our Sun is a fairly standard star with core temperatures able to fuse protons in a complex series of reactions known as the p-p cycle. Helium, gamma rays and lots of energy are produced in the fusion process ... and yes, neutrinos. Neutrinos were first postulated by Wolfgang Pauli and subsequently detected in 1956 [2]. Nuclear theory predicts that vast quantities of neutrinos are produced by the Sun but as they have no mass (or perhaps very little) and no charge their interaction with ordinary matter is tiny. 50 trillion solar neutrinos pass through a human body every second [2]!

In the 1970's a classic experiment was set-up in a mine in USA by an equally classic experimental scientist, Ray Davis [2,3,4]. It's aim was to detect these illusive neutrinos (νe) by their very slight interaction with chlorine to form argon. If the neutrinos have enough energy (νe > 814 keV) the following reaction is possible:

3717Cl + νe3718Ar + e

Using 100,000 gallons of cleaning fluid (a cheap source of Cl atoms) and some superb chemistry they were able to detect just ca. 12 Ar atoms being produced per month (that's 12 Ar atoms in a tank of ca. 1030 atoms!) [4]. This was about 1/3 of what was expected, causing considerable debate among the theoreticians. One explanation for the 'neutrino number discrepancy' was that neutrinos might come in three types, or 'flavours': electron, muon and tau neutrinos. As the Cl → Ar reaction requires electron neutrinos (νe) this explains why the signal was only 1/3 of the expected value [3,4].

The film seems to suggest that the planetary alignment is somehow changing the type of neutrinos produced, perhaps to one of the other two types. 'Flavour' oscillations, where the neutrinos change type, have been predicted and, of course, used to account for the neutrino number discrepancy [2,3,4]. But even if there was some astro-physical mechanism for this there is no reason given the tiny, tiny interaction, even of vast quantities of neutrinos, that this would have any realistic effect on the thermal process going on in the Earth, certainly not over such a small time scale of a few months, or years of the build-up in the film. In summary then; the science is shaky (as if you needed to be told!), so don't bother moving to the Himalayan high ground just yet ....

References and Links
[1] 2012, Columbia Pictures 2009.
[2] wiki page on neutrinos
[3] Project Poltergeist, BBC Horizon TV, 18th March, 2004
[4] Neutrino from the Sun, Frontiers in Astronomy, J N Bahcall, Scientific America, 1969.


How teachers can use these articles in a lesson

Why Hollywood Science

Open University Hollywood Science web site

Call for clips - do you have a film clip that needs investigating?


Dr Jonathan Hare, The University of Sussex
Brighton, East Sussex. BN1 9QJ.

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