Let’s say we have a number line from negative ten to positive ten, where negative ten is black, zero is grey, and ten is white. On this number line is a point whose initial position is random, and whose position at every time step is random. The absolute value of the point constitutes the entropy of the system you describe.
We can see now that a point on the leftmost position, -10, has a 19/21 probability of becoming “more grey” or “less entropic” at the next step, and a 2/21 probability of remaining at the same distance from grey or of having no change in entropy. So does a point on the rightmost position. Here are the other values (you may need to switch forum themes at the bottom left of the page):
Position to Entropy
Pos | Less | Same | More
-10 | 19/21 | 2/21 | 0/21
- 9 | 17/21 | 2/21 | 2/21
- 8 | 15/21 | 2/21 | 4/21
- 7 | 13/21 | 2/21 | 6/21
- 6 | 11/21 | 2/21 | 8/21
- 5 | 9/21 | 2/21 | 10/21
- 4 | 7/21 | 2/21 | 12/21
- 3 | 5/21 | 2/21 | 14/21
- 2 | 3/21 | 2/21 | 16/21
- 1 | 1/21 | 2/21 | 18/21
0 | 0/21 | 1/21 | 20/21
1 | 1/21 | 2/21 | 18/21
2 | 3/21 | 2/21 | 16/21
3 | 5/21 | 2/21 | 14/21
4 | 7/21 | 2/21 | 12/21
5 | 9/21 | 2/21 | 10/21
6 | 11/21 | 2/21 | 8/21
7 | 13/21 | 2/21 | 6/21
8 | 15/21 | 2/21 | 4/21
9 | 17/21 | 2/21 | 2/21
10 | 19/21 | 2/21 | 0/21
Total all of those probabilities together and we can see that after one instant, there is a 200/441 probability that the system will move to a less entropic state, a 41/441 probability that the entropy will not change, and a 200/441 probability that entropy will increase. In percentages, that’s about 45% for entropy to decrease, 9% to stay the same, and 45% to increase.
And this is after assuming the equiprobability of microstates at each measure of entropy, which I do not wish to assume.
~Max