Entropy and life

Motivated by thoughts about the fate of the Jove, I seem to have dived deep into a rabbit hole. With the help of the Lamp’s library assistants, I have been digging up books about the physical constraints that would apply even to hyper-advanced civilizations. 

In that discussion, entropy plays an important role.

Entropy is a measure of missing information or chaos. That sounds like a vague concept, but physics manages to give it a mathematical definition that allows to put a number on it. The sort of chaos that can be captured by the physical concept of entropy is not about political chaos and not really about the mess of books and papers on my desk. Rather, it is chaos at a microscopic level, in the arrangement of atoms or other (sub)atomic building blocks of life.

Maximum entropy would occur when everything is completely mixed up, a uniformly mixed soup of all sorts of atoms. Low entropy, by contrast, occurs when these atoms are perfectly sorted, for example when they are arranged in a perfect, infinite crystal, frozen down to the lowest temperature.

Both extremes represent death. 

Life, with its complex arrangements of atoms, is neither maximum entropy nor extremely low entropy. It exists somewhere in between the two. It requires complexity and structure, which is neither maximal chaos nor maximal order at the microscopic level. 

The main and most intriguing property of entropy is that it always grows over time. That is known as the second law of thermodynamics. As you live your life and think your thoughts, the processes that occur while doing that will increase entropy. The atoms get knocked out of their original formation, and the chaos and loss of in-formation increases. If you get locked up in a closed box and one waits for a very long time, you will ultimately turn into a nasty, bloody, high-entropy structureless goo. 

This tendency of entropy to always grow certainly is depressing.

But there is also hope! The second interesting property is that entropy can be transported. To maintain your atoms in their formation, you must expel the entropy that is being generated by the processes in your body to somewhere else. Entropy is the ultimate waste that we will always need to get rid of, no matter how advanced we become.

As it turns out, we live on a big stream of entropy coming from our star and going off into space [*], and we can dump our little excess entropy waste into that big stream! As a civilization becomes more advanced, it can perhaps manage its energy consumption or harvesting in a more efficient way, but it will always have to get rid of its entropy. That is true even if we become virtual beings, as manipulating digital information also produces entropy. 

To clarify that, I’ll have to look at the entropy associated with manipulating data next.

[*] Technical details: The stream starts at Amarr's star, which sends us low-entropy radiation characteristic for 4436 K. The higher the temperature of a celestial body, the lower the entropy associated with some flux of energy coming from the celestial body (in fact the entropy is inversely proportional to this temperature). The light from our star powers life on Amarr, and gets re-radiated out back into space at the temperature of our planet, about 300 K. Incoming energy needs to balance outgoing energy to get a planet in thermal equilibrium, but that is not true for entropy. Our planet radiates out high-entropy, mostly infrared radiation. So, we have a low entropy stream coming in, and turning into a high-entropy stream as it moves out. Part of that higher entropy comes from us doing our thing on the planet, and maintaining our microscopic structure, by dumping waste entropy into that stream. 

Specifically, and perhaps just to prove that physics can put numbers on it: our star provides 450 Watt/m^2 of energy flux to Amarr prime, which must be radiated back out to space. This corresponds to about 1 J/K of entropy that is dumped into space per second, per square meter of planet surface.