In a previous post, I commented that life is like porn. We know it when we see it… or at least we thing we do. It’s really astonishing how arrogant we humans can be. There’s a dedicated group of believers who think that the entire universe (all 4.077 x 10^32 cubic light years of it) exist just for them. We have trashed our planet because some moldy old book of legends says we get “dominion over the Earth”.
Yet, we, in all of thousands of years of sentience, can’t define something that we see around us all day. Porn… I mean… life.
When I was in high school, we were taught that there were some specific characteristics of life. We were taught six of them.
- Made of cells
- Grows and Develops
- Homeostasis
- Reproduction
- Metabolism
- Responds to the environment and movement
Well, that’s really eight. Another version of this list also has “adapts”. But let’s be skeptical for a minute. If we define life as it must have all of these things, then we are immediately leaving out computer systems. They are not made of cells. They don’t reproduce… well computers don’t, but software can. They don’t metabolize… well, they take in energy. They don’t adapt… except some software does (even going so far as to develop logical functions that weren’t programmed into it). They don’t maintain homeostasis… except for my computer which has a fan tied to the motherboard which increases speed as the CPU works harder.
So, is a computer alive? Of course not… I think.
Here’s another interesting question. An organism, say a parrot, dies. It’s dead…
“He’s not pining, he’s passed on. This parrot is no more. He has ceased to be. He’s expired and gone to meet his maker. He’s a stiff, bereft of life, he rests in peace. If you hadn’t have nailed him to the perch he’d be pushing up the daisies. He’s rung down the curtain and joined the choir invisible. This is an ex-parrot!”
Yet, everything I’ve read has stated that there is a lot of cellular activity that continues after death. Muscles can twitch, cells can divide, all kinds of things. I understand ‘brain death’, but there is still life left in the body.
I think I can make things even weirder. Ready? What about an apple that has fallen from a tree? Is it alive?
Well, let’s look at our list. Does the apple reproduce? No. It is part of the reproductive system of the tree, but it doesn’t reproduce. Does the apple adapt. metabolize, respond to the environment, grow, develop, or maintain homeostasis? No, the apple does none of these things, so is it not-alive? Of course it’s alive… I think.
There are cells in the apple that are alive and kicking. And individual cells may be doing the things listed, but the apple as a whole is not. So why is an apply considered to be ‘alive’ while a dead parrot (that has cells doing at least some of those things) considered ‘not alive’?
This isn’t just an academic question. This is a real puzzler and greater minds than myself have thought about this for decades and are no closer to an answer. I’m reminded of a story I read. It seems there was a big conference and a bunch of scientists and philosophers got together and tried to define life. Every single time someone came up with a definition of life, someone could provide a counter example of something that was considered alive, but didn’t meet that requirement. Finally, they narrowed it down to one thing. The ability to reproduce. if something could reproduce, then it was alive. Everyone congratulated themselves, until a small voice from the back piped up, “Then one rabbit by itself is not alive. Only two rabbits together can be alive.”
I don’t know how true this is, but it was reported to me as being true.
I don’t know if we’ll ever have an actual answer, but as we get closer and closer to things that science fiction writers dreamed up decades ago, it’s something we need to think about. Can a computer system or program ever be ‘alive’? Is a silicon-based intelligence alive or not?
