Biological waste = entropy + mass

Here is a cool question I recently answered on Physics Stack Exchange about how organisms "work" on the most fundamental level.    

Q. From reading Nick Lane's "The Vital Question", I recently learned that biological processes and the formation of biologically organized structures (cells, organisms, metabolism, etc.) generate a large amount of waste heat (entropy) that gets emitted into the environment. What connection does this "waste heat" have with biological wastes (poop etc.) arising from metabolic processes? Are they equivalent? 

A. They are similar. The key thing to understand is that organisms are constantly engaged in a life-and-death, literally, battle against the forces of chaos. That might sound like a line from a fantasy novel, but it's true. The second law of thermodynamics dictates that disorder (entropy) constantly increases, and if an organism doesn't do something about this, its systems will quickly succumb to disrepair. 

Luckily, even though entropy must increase, physics allows one system to decrease its entropy by transferring it to another, for example to its surroundings. And this is exactly what organisms do in order to fight increasing disorder within them. Except it's not super easy to expel entropy, it's much trickier than expelling matter. 

What's the problem? Basically, the surroundings most of the time are close to being at capacity, they don't want to absorb more disorder because they are already in a very disordered state. The most disordered state is called the thermodynamic equilibrium, and most of the time the natural environment is pretty close to equilibrium. A more precise statement would be that the deviations from equilibrium are hard to make use of. A familiar manifestation of that is that it's quite a tough technological challenge to generate a lot of useful energy from stuff around us, like wind, the sun, and almost everything else.

The solution that organisms found is to find a part of the environment that is in a relatively low entropy state, absorb it, increase its entropy while lowering their own entropy, and then expel the high entropy waste products. Pooping, urinating, breathing out are all examples of this fundamental process.

So how does expelling these material waste products compare to just expelling heat (which is a byproduct of many processes in an organism)? Both expel extra entropy into the environment (i.e. reduce the organism's entropy while increasing the environment's entropy). Also, both expel extra energy. But in addition to that, the biological wastes also expel extra mass, whereas losing heat to the environment doesn't.

Here's a great video explaining the role of entropy in powering the whole Earth's ecosystem:

Q. Does this entropy increase meaningfully make the environment more difficult for biological processes to sustain themselves?

A. No, because the biosphere expels the extra entropy into space. On the planetary scale, the Earth receives low entropy photons from the Sun, and expels high entropy photons into space. 

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