Spacetime curvature effect on chemistry Do current chemistry / astrophysics / stellar chemistry calculations include the effects of the curvature of spacetime on chemical reactions?
For example, the heat transfer from a point closer to the center of the Sun would be influenced by the gravity well, regarding relativistic time distortion, as the energy moves up the well. 
 A: What you're talking about are the so-called post-Newtonian effects of general relativity:  those effects of gravity that are not predicted by Newtonian gravity.  As you might be aware, general relativity has Newtonian gravity as a limit:  if a particle's velocity is small compared to the speed of light, and the sources of gravity are not moving quickly either, then the predictions of Newtonian gravity are recovered to a very good approximation.  
Now, when I say "a very good approximation", I mean that there are very small corrections that do exist to the Newtonian predictions.  These corrections are governed by two dimensionless parameters:


*

*The speed of the particles moving in the potential, divided by $c$;  and

*The Newtonian gravitational potential divided by $c^2$.  


Any corrections to the effects of Newtonian gravity will generally be on the order of one of these two parameters.  So, for example, in the center of the Sun the gravitational potential is on the order of
$$
\Phi \propto \frac{G M_\odot}{r_\odot} \approx 6 \times 10^{7} \, \text{J/kg},
$$
which means any corrections due to general relativity will be on the order of 
$$
\Phi/c^2 \approx 7 \times 10^{-10}.
$$
Similarly, the thermal velocities of the hydrogen nuclei in the center of the Sun ($T \approx 15 \times 10^6$ K) will be on the order of
$$
v \propto \sqrt{kT/m} = 350,000 \, \text{m/s}
$$
and so the corrections due to general relativity due to the motions of these particles will be on the order of
$$
v/c = 1 \times 10^{-3}.
$$
So for a star like the sun, the effects are probably pretty negligible, and easily swamped by our imperfect understanding of things like nuclear cross-sections, magnetic fields, and so forth.  
If you want something where relativistic effects do matter and are taken into account, you have to look at things like the hydrodynamics inside a neutron star, for which $\Phi/c^2 \lesssim 1$.  But you can't really call the processes inside a neutron star "chemical" by any stretch of the imagination.  Really, almost any situation in which you're doing something that could be called "chemistry" is almost by definition non-relativistic, and to the extent that you need to include gravity, the Newtonian approximation to the full laws of general relativity will work just fine.
