I'm not sure if this is asked anywhere else before, but so far my search isn't fruitful.
I'm in my second bachelor of physics and mathematics, and currently taking a thermodynamics course. We just got introduced to the second law and entropy, but I am confused by its deeper meaning. I understand that entropy always increases and in our course text (An introduction to thermal physics by Daniel V. Schroeder) this is explained by microstates of a system. I understand that systems with more 'disorder' have a higher chance of occuring than systems with a lower disorder. The thing that bothers me right now is why nature obeys this statistical argument. Just because combinatorics says a certain configuration is more likely doesn't imply that nature will develop to that situation.
My question is: why does a system tend to a configuration with more disorder.
I've read on several pages that this is because 'energy flows downhill'. I can see how this solves my question, because if the energy flows downhill, then it's quite easy to see that the result is a system with energy more spread out, a system with more disorder. But then again why does energy flow downhill? What drives the fluid of energy between systems? On some internet pages, the answer to this question is 'because entropy increases', but this brings us back to the original problem.
In conclusion: why does energy flow downhill or why does entropy increase, explained on a fundamental level.
I thank you in advance.