> at some point there is really no difference between impossible and 'incredibly small probability'. This is not true. Using your air molecules example: Ever

> at some point there is really no difference between impossible and 'incredibly small probability'. This is not true. Using your air molecules example: Every microstate (i.e. location and speed of all the molecules) possible under the given macrostate (temperature, number of molecules, etc) has a probability of happening of 0, but aren't impossible, simply because the microstates are real variables and real numbers are uncountable. Impossible microstates also have 0 probability but are obviously not the same.