More on “Will you acknowledge your mistake?”

In response to yesterday’s post, a very smart scientist-friend of mine sent in this:

Brian, I just read the “Q & R: will you publicly acknowledge and correct your mistake?” item on your blog. Much ado about very little, in my view, but I’m happy you took him/her seriously and addressed the questions.
That said, I think you need to know that both of you are incorrectly understanding the second law of thermodynamics….
First, some terminology:
An open system is one which is completely open to passage of matter and energy across the system’s boundaries. The Earth is an open system
A closed system is one which is open to the passage of energy but closed to the passage of matter across the boundaries. The Earth is approximately a closed system, but not completely, as several tons of meteoroids strike the atmosphere each day and we lose a bit of atmosphere due to sunlight pressure on molecules in the upper reaches of the atmosphere.
An isolated system is one which is completely closed to the passage of both energy and matter across its boundaries. The Earth is not an isolated system
The second law of thermodynamics says that the total entropy of an isolated system cannot decrease. A reduction of entropy is what happens when something gets more ordered, less random (speaking informally — a precise definition is too technical).
The second law says nothing about open or closed systems, and that’s where you’re right in spirit, but not in wording: As the Earth is not an isolated system, the second law does not pertain, so it is perfectly okay to see increasing order in the Earth.
That stale old second law argument against evolution has been around for many years …

If you can’t know everything, it’s great to have constructive critics and smart, helpful friends.