Can a Living Creature Be as Big as a Galaxy?

Post by alextheparrot » Sat, Aug 05, 2017, 9:01 PM UTC

21 wrote: post #75

alextheparrot wrote: post #73

Earlier quoted context omitted.

Is a sterile human not alive by this definition? I find that life needing to reproduce is a questionable condition. If we say reproduction is not requisite, then neither is evolution as evolution requires generations. "Evolve as survival dictates" is a bit pointless, as if you don't change to survive (Assuming the change is requisite) you do not survive. Survival is defined as still being alive, so if you don't survi…

If you remove reproduction, remove evolution, what else is left? Evolution doesn't necessarily involve reproduction. A sufficiently advanced human (or computer) could enhance itself technologically, continuously replace it's organs (Ghost in the Shell), even change it's form and this would count in my book as a form of (non-biological) evolution. You could say the same thing about culture. I think that definition is…

Post by Falling3 » Sat, Aug 05, 2017, 9:04 PM UTC

alextheparrot wrote: post #70

Koshkin wrote: post #62

Since proteins cannot exist in space, then, using the currently accepted definition of "life" at the basic level as the complex of processes that allow protein molecules to exist, then the answer must be 'no'. On the other hand, it is an interesting mental exercise to also consider other reasons why such creature might be impossible. One reason could be because the time needed for such creature to grow from something…

Proteins (Or the ability to make them) is not requisite for life, nor are nerve impulses, nor is evolution. If we encountered an immortal (Does not evolve), sterile (Does not reproduce), silicon-based alien (No proteins), that would most certainly be heralded as finding extraterrestrial life. Reasoning about much large systems than our own is difficult. Imagine a bacteria attempting to reason about a human - the exis…

Post by alextheparrot » Sat, Aug 05, 2017, 9:17 PM UTC

Koshkin wrote: post #78

alextheparrot wrote: post #73

Earlier quoted context omitted.

Is a sterile human not alive by this definition? I find that life needing to reproduce is a questionable condition. If we say reproduction is not requisite, then neither is evolution as evolution requires generations. "Evolve as survival dictates" is a bit pointless, as if you don't change to survive (Assuming the change is requisite) you do not survive. Survival is defined as still being alive, so if you don't survi…

Well, your sterile human appears to be a strawman. Obviously, a person may be sterile, but the organism cannot stay alive if the continual process of reproduction (of cells, their organelles, and molecules) inside it ever stops. A multi-cell organism is an emergent phenomenon that helps protein-based molecular structures to do their thing ("life").

Post by alextheparrot » Sat, Aug 05, 2017, 9:20 PM UTC

Falling3 wrote: post #83

alextheparrot wrote: post #70

Earlier quoted context omitted.

Proteins (Or the ability to make them) is not requisite for life, nor are nerve impulses, nor is evolution. If we encountered an immortal (Does not evolve), sterile (Does not reproduce), silicon-based alien (No proteins), that would most certainly be heralded as finding extraterrestrial life. Reasoning about much large systems than our own is difficult. Imagine a bacteria attempting to reason about a human - the exis…

I'm not necessarily disagreeing, but what's the definition of life you're saying that would satisfy?

Post by Koshkin » Sat, Aug 05, 2017, 9:29 PM UTC

laumars wrote: post #68

Koshkin wrote: post #62

Since proteins cannot exist in space, then, using the currently accepted definition of "life" at the basic level as the complex of processes that allow protein molecules to exist, then the answer must be 'no'. On the other hand, it is an interesting mental exercise to also consider other reasons why such creature might be impossible. One reason could be because the time needed for such creature to grow from something…

There are animals on Earth with a decentralised nervous systems (most famously the octopus) and there isn't any confusion about whether they're classed as one animal or multiple ones.