I hear a lot of comments about how entropy is related to aging and death but I was reading up about it and I cannot seem to fully understand it.

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Your body spends a whole lot of energy reversing entropy.

Entropy would really like to redistribute the salt evenly in your body, and remove the electrical charges from your brain, and pop your blood vessels.

Lots of the energy from the food you eat is just used to keep that from happening. It’s called “homeostasis”.

But that’s the only connection, aging and death (from aging) is more because your cells can only divide so often.

Every time your DNA gets replicated a little bit is snipped off. You come prepared though and the beginning and end of your DNA is just a long stand of useless code that you won’t miss. Eventually – after at most 120 years – the useless stuff is gone and your actual genes you need to live are snipped and you die.

Entropy is a measure of how many possible ways there are for a bunch of particles to be arranged in this particular way. Let’s take a million bricks and arrange them into a building. There is a certain number of ways these bricks can be rearranged while still comprising that same building. And now let’s push that building over and turn it into a pile of bricks. The number of ways a million bricks can be just a pile is much larger than the number of ways they can be a particular building. This means that the entropy of a pile of bricks is larger than the entropy of a building. In cause of a human body, the number of ways its molecules can be arranged so that the body is actually alive and functioning is rather limited. Conversely, a dead body can have its molecules arranged in pretty much any way and still stay a dead body. Therefore, the entropy of a dead body is larger than the entropy of a living body. The second law of thermodynamics says that in a closed system entropy never decreases. Therefore, constructing a building or growing a human – activities that decrease entropy locally – require using external energy and increasing entropy elsewhere.