PART 2 OF SESSION 2 OF COURSE 1

What we are about to discus now is DISTINGUISHABILITY. Let us say that you had ten thousand golf balls. Each of them were identical to one another. Let's say that each of the golf balls were placed with the exact same orientation in terms of where their up, down, and side-to-side were. Let us now say that the golf balls were evenly spaced into five rows and two columns. Let us say that each of these balls rested in their hollows, respectively. Choose any two golf balls. Switch their spots. You would not be able to tell that they were now in a different arrangement, except that you were the rearranger. Now, choose any number of golf balls and switch their spots. You still will not be able to see a change in how these appear. This is considering that you obeyed the initial rules. Yet, the fact of the matter remains, each golf ball is a different golf ball, even though these all look the same. Now, if the golf balls were not of themselves completely homogeneous in appearance, or, in other words, smooth and evenly spread in arrangement, and you did not position all of the golf balls in the same relative orientation per spot, where these balls were in their respective hallows, you would be able to distinguish a difference in how the golf balls appeared. Thus, the array of ten thousand golf balls would not be homogeneous, and you would notice differences in parts of the array. Thus, in this case, switching where the golf balls would be would certainly be able to alter the appearance of the array. If this type of orientation per spot in the array were maintained, then, although the array wouldn't be homogeneous, the appearance of the array would appear the same no matter which golf balls were switched. Now, if you didn't switch which hollows the golf balls were in, yet you were to alter the orientation of some of the golf balls, then the appearance of the array were to alter.
In the prior paragraph, the golf balls were said to be "indistinguishably different" when switched with no apparent change. In the next circumstance described above, in certain circumstances, it would cause the golf balls to be indistinguishably different, while certain related circumstances would cause noticeable differences when the golf balls switched places. The last incident described is one where there is distinguishable difference, even though the balls were not relocalized to different hallows.
Inside of an atom, and throughout our planet, electrons are switched in a process that is indistinguishable different. When two identical atoms switch positions, the difference is not one that you can detect a difference from unless you were analyzing those atoms right as they switched places through the extrapolation of physical evidence. Furthermore, if a molecule had a certain polar bond, and there was another molecule of the same type nearby, and the two molecules had reverse orientation, it would be easier to distinguish these when these were in the process of switching location.