Thanks @photon_lines! In your temperature diagram, you mention that every point will take the average of the neighboring points. However, the equation is not a constraint on the temperature but on the "change of the slope (or gradient) of the temperature". The bigger the slope (in space), the faster (in time) the temperature changes at that point!
'The bigger the slope (in space), the faster (in time) the temperature changes at that point!' - Sorry but I'm not really reading you here. If the points around an 'atom' a symmetrically and equally far away when it comes to the point in question but are opposite in magnitude (i.e. imagine having a point with temperature 12 degrees Celsius which is surrounded by a neighboring points which have temperatures of 8 degrees and 16 degrees (so the delta is +4 and -4) then the temperature here will stay the same. The slope of the temperature field has nothing to do with this - unless maybe you're alluding to the slope of something else? I think I should have maybe explained this equation in terms of 'concavity' instead of using the methodology which I used - you can get a good grasp of this in this link: https://www.youtube.com/watch?v=b-LKPtGMdss
Thanks for taking the time to respond and analyze my comment! - The bigger the slope (in space), the faster (in time) the temperature changes at that point -
I have to confess that I got it wrong, indeed: the right side of the equation is a Laplacian. But, rather than describing an average in temperature, it describes the divergence of the temperature field.
