What is life?

Question

We are essentially complex molecular machines. That's the hardware. What exacly is the software?

Let me explain the question a little more. Jack is alive at 10:24. By 10:30, he dies in his sleep. All the molecular machines are sill there. The energy is also there. What is different immediately after he dies? Yes, I know he's now dead. So, what happened?

Answer 1

The "software" is our DNA. Even if two people were exposed to exactly the same "input" (achievable only by simulated reality), they would still behave differently due to their genetic code.

When we die of old age, it is because the software is corrupted. Basically, chromosomes are not copied perfectly when cells divide - instead, a bit of genetic material on both ends of each chromosome is lost. However, when we are born we have useless DNA there, which can be wasted. After about 50 cell divisions these useless ends (called "telomeres") have worn down and upon further division vital DNA will be lost. (Cells have to divide; they cannot survive indefinitely because imperfections in cellular respiration lead to the leak of free radicals which damage proteins within the cell.) So - the energy is still there and the hardware is still there, but the software isn't. Just like your computer won't work if the master boot sector is corrupted.

But... not everyone would agree. Some people believe that if I made an exact copy of you, right down to the last electron spin, it would not be alive - that the living you has a "soul", that the soul is what allows life to exist. And we cannot prove them wrong - after all, scientists have not yet managed to explain how consciousness is possible. One day, we may know the truth. For now, we can only wonder.

Answer 2

The molecular machine broke. It's that simple. Let me give you an example: if something destroys a single transistor in your PC's CPU (and that would be one in a couple hundred million!), the machine wouldn't even boot. And there would be no way anyone on Earth could repair that one transistor. None. You would have to replace at least the whole CPU chip.

In a living being you have trillions (actually more than that) of molecular subunits. Most of those have to be working correctly. If a few in a thousand show a serious malfunction, you die. That ratio is much better than in a technical system, but life is evolved to last any longer than necessary to procreate. And that is just it... life breaks and then dies.

And is you want to drive the machine analogy further, even if you die, your organs don't have to. It's called an organ transplant. Most of your body would be reusable. We just don't because there is no demand, even if there is more demand than supply for some organs.