I came across something on the internet about ‘respirocytes’, which are man made red blood cells (still on the drawing board as far as I know, but feasible). Some designs, if successful, would allow people to function on one lungful of air for 4 hours and sprint for minutes without taking a breath.
Imagine if someday technology could produce a replacement for every piece of say, an alligator, and we took one biological specimen, and began replacing everything, the claws, muscular fiber, nerves, gi tract, etc with its man made counterpart. At what point does the thing stop being “alive”? Is a totally man made machination that looks eats, shits, creeps around in slow muddy rivers, thinks and otherwise totally *is *an alligator still not “alive”? If we were to create such a counterpart to homo sapiens, do we give it rights? How about a desktop computer with the software equivalent of the human brain that has the exact same kind of logical processing and emotional responses as any one of us do? Could you marry an absolutely charming, deep, funny as hell software program that you just can’t not fall in love with?
If this is a little too 17-year-old-just-read-his-first-good-science-fiction-and-he-thinks-he’s-profound for you guys, you’re kind of right. That’s mostly why I didn’t put this in GD or something, for fear of being totally shut down. So lets hear it people, what do you think?
I’d say that life is a particular style of organization and processes. So, if you did take an alligator or a human and replace their natural tissue with artificial replacements that fulfilled the same functions, it would still be alive. And I’d consider the result just as deserving of rights as anyone.
I’d call a sufficiently sophisticated simulation of life alive as well; just not alive on the same physical level we are. A program that thinks is another matter; I don’t think enough is known about the details of how the mind and organic life works to say if they belong in the same category. But even if they are, a program could easily be different enough to not qualify. That being said, there’s no reason that it couldn’t be unliving but a person.
Physics shows us all things tend to simpler and simpler form, until the universe reaches an equal distribution of everything everywhere, “heat death,” entropy.
“Life is the force that organizes matter into more complex forms.”
Yeah, but we’re self-organized organic compounds. Try teaching a bottle of ammonia cleaner the nuances of Alekhine’s Defense.
We can pretty readily establish some minimum criteria for life (metabolism, reproduction, excretion) that allow one to determine that a system is not alive, but qualifying life itself is somewhat more complex; for instance, crystalline and some protein structures can self-catalyze replication (albeit of structures far more simple than those found in cellular organisms), and under suitable conditions RNA will replicate and even form spontaneously given biological precursors like polycyclic aromatic hydrocarbons. All of these perform life-like functions, including the moderation of thermodynamic gradients (i.e. they use energy to build structures, which then use more energy to build more structures, et cetera) but would not be recognized as being “alive” by any accepted standard on the basis that they don’t have any kind of cellular or individual organization, have no mechanism for positive robustness versus replication errors, and don’t fulfill the requirements as an autocatalytic set. This leads to Francis Crick’s central dogma of molecular biology: that genetic information travels only from genes (encoded in DNA) to proteins via a transcription to an intermediate nucleic acids that act as a template for protein production (in addition to other editing and replicating functions).
If you were able to make a construction that was sufficiently indistinguishable on a molecular level from living organisms (i.e. cells had individual metabolism and replication capability), I think we’d have to consider it to be alive even if the in toto organism itself is a non-reproducing construct like the manufacture allegator in the o.p.'s example. On that basis, a humanoid robot like Star Trek’s “Data” coulud not be considered to be living in any technically biological sense, as he is manufactured from discrete electrical and mechanical components that presumably are not self-replicating. However, the character of Lt. Data clearly demonstrates sentience, on which basis he may be accorded rights even though he does not fulfill the requirements of being alive. The real likelyhood is that a constructed system that is sufficiently complex to be demonstratably sentient will probably be some inseperable mix of identifibly organic and manufactured, and the issue will be less of questioning whether it is alive but rather whether and how much it has free will and autonomous thought; a question one might as well ask of evolutionarily-derived organisms as well.
Now here’s where I differ. I think that if it acted alive; was capable of metabolism and self replication and so forth, but not at the molecular level, it would still be alive. It would just be alive at a larger, coarser scale than we are.
As I see it, bodies are living things, made of smaller living things ( cells ), which are made of unliving things ( molecules ). If you made a creature whose individual “cells” couldn’t reproduce etc on their own, but whose body in it’s entirety could replicate, grow, heal, metabolize, etc; you’d have a living thing, made of unlving things ( pseudo-cells ), made of unliving things ( molecules ). They just wouldn’t qualify as alive until a higher organizational scale compared to us.
Has a consensus been reached about whether viruses are alive, or not? While they certainly exhibit some of the characteristics of life, they lack many others. Last I’d paid any attention to the issue, the debate was still going strong.
It would not be alive under any definition that would be recognizable to biologists. Cellular organization and all that stems from it (functional specialization, discretized replication, robust self-repair, internal metabolism, selective adaptation and inheritance, et cetera) aren’t just convenient; they’re essential to any system we could clearly define as being alive. You could hypothetically construct a mechanical robot that could construct identical robots. Would it be alive? No; it would still be a designed machine that might simulate some characteristics of being alive, and it might even display sentience (albeit by means programmed into it) but it would not be living in any accepted technical definiton.
Now it is possible that a system constructed of other than organic carbon-based macromolecules might fulfill the prerequisites of life, but it would still have to be built with a cellular architecture in which the code for construction and operation is physically transmitted to future generations. Cellular and intra-cellular organization is the key to reducing the complexity of life to managable, reproducible blocks.
Viruses are certainly not alive by any reasonable definition; they have no metabolism nor means of self-replication outside of the cells of living organisms. This isn’t to say that viruses just emerge fully formed from the hinterlands; they are widely thought to be derived from other organisms which have ‘learned’ evolutionary success (from a gene-centric point of view) by shucking all of the extra mechanics required for self-replication and autometabolic processes, and instead adapting to a parasitic lifestyle. This is of course a very successful strategy for them and the genes within. It also may be a very successful strategy for some living organisms to play host to them, especially simple asexual prokaryotes with whom viruses may easily exchange genetic material, allowing the hosts a wider range of genetic variation and dispersal that would otherwise occur by genetic drift alone.
No real answer to the meat of your question, but I just wanted to comment on this bit.
-there isn’t sufficient oxygen in a single lungful of air to sustain you for hours, no matter how it’s processed - I imagine they must be talking about artificial cells that simply have far greater storage capacity than ordinary natural ones - which may or may not be plausible, but it’s going to require many lungfuls of air to absorb 4 hours worth of O2.
-It sounds incredibly dangerous. Walking around with that much concentrated oxidiser in your system - if something went wrong, you could quite easily catch fire or explode.