I started reading about entropy and the second law of thermodynamics.
Different sites give different definitions and meanings of this law.A few of them- 1.Disorder always increases 2.heat always flows from a hot to a cold object 3.Unusable energy of a system always increases.
In the first one,what is really meant by disorder?What is the true meaning of disorder?Does disorder depend upon the observation of a conscious mind,or does it have a meaning even without an observer?
Also, are all these three definitions actually interconnected?
The third definition made the most sense to me;but since it is a law,can it actually be proven or is it just accepted because of experimental evidence?Can human find ways to utilize this unusable energy in an efficient way and still not increase the entropy of the system? And what does "unusable" energy mean?Aren't usable and unusable energy only significant for humans?Why does the universe even care if energy can be used or not?
I have just started understanding this topic.An answer without maths and one which gives conceptual clarity would be appreciated.