A quick back-of-the-envelope calculation gives a total energy release for 2D->He on the order of 25 MeV. Even if it happens in two or three steps, we are still talking fairly hard gamma rays. Some will be absorbed, of course, but absorbing a 25 MeV photon just gives you a 25 MeV electron instead (the electron mass times c^2 is about half a MeV, so the electrons in question are going to be the next best thing to super-relativistic).

I seriously doubt that a perceptible fraction is released as vibrations in the lattice - at least initially: Ionisation energies are on the order of tens of eV, binding energies typically an order of magnitude less and excitation energies are maybe half that. If even one percent of the released energy is absorbed directly by the six nearest atomic bonds, there is a better than even chance that you no longer have a lattice.

Modelling what happens when you kick stuff that hard can get kinda messy, and nuclear physics was never really my thing, but I would definitely say that if they have fusion, then they will have more convincing indicators than heat.

Then again, I never much cared for the Kuhnian notion of paradigms either, although that may have more to do with overzealous disciples than the original, since I haven't found time to read it yet.

- Jake

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