what is meant is a simple external energy source such as radiation or a simple chemical source of energy.
I do not see how this answers the objection. All you did was add the qualification ‘simple’ to the existing ‘external’. Is this meant to exclude fire, or include it? If the former, how does it do so? Presumably plant matter is a sufficiently “simple” source of energy, since otherwise you would exclude human digestion; plant matter also burns.
The chemistry that goes on inside a star is very much in equilibrium conditions.
Again, which equilibrium? The star is nowhere near equilibrium with its surroundings.
Viruses are not self-sustaining systems,
Neither are humans… in a vacuum; but viruses are quite self-sustaining in the presence of a host. You are sneaking in environmental information that wasn’t there in the original “simple” definition.
Look at my reply to kalium. To reiterate, the problem is that people confuse objects with processes. The definition I gave explicitly refers to processes. This answers your final point.
All you did was add the qualification ‘simple’ to the existing ‘external’. Presumably plant matter is a sufficiently “simple” source of energy, since otherwise you would exclude human digestion; plant matter also burns.
I already conceded that it’s a fuzzy definition. As I said, you are correct that ‘simple’ is a subjective property. However, if you look at the incredibly complex reactions that occur inside human cells (gene expression, ribosomes, ATP production, etc), then yes, amino acids and sugars are indeed extremely simple in comparison. If you pour some sugars and phosphates and amino acids into a blender you will not get much DNA; not nearly in the quantities that it is found in cells. This is what is meant by ‘far from equilibrium’. There is much more DNA in cells than you would find if you took the sugars and fatty acids and vitamins and just mixed them together randomly.
Again, which equilibrium? The star is nowhere near equilibrium with its surroundings.
Ok, chemical equilibrium. This does not seem to me like a natural boundary; why single out this particular equilibrium and energy scale?
As I said, you are correct that ‘simple’ is a subjective property.
I think you’re missing my point, which is that I don’t see how your definition excludes fire as a living thing.
The definition I gave explicitly refers to processes. This answers your final point.
I don’t think it does. A human in vacuum is alive, for a short time. How do you distinguish between “virus in host cell” and “human in supporting environment”?
why single out this particular equilibrium and energy scale?
Because the domain of chemistry is broad enough to contain life as we know it, and also hypothesized forms of life on other planets, without being excessively inclusive.
I think you’re missing my point, which is that I don’t see how your definition excludes fire as a living thing.
I tried to answer it. The chemical species that are produced in fire are the result of equilibrium reactions http://en.wikipedia.org/wiki/Combustion . They are simple chemical species (with more complex species only being produced in small quantities; consistent with equilibrium). Especially, they are not nearly as complex as compared to the feedstock as living chemistry is.
I don’t think it does. A human in vacuum is alive, for a short time. How do you distinguish between “virus in host cell” and “human in supporting environment”?
They are both part of living processes. The timescale for ‘self-sustaining’ does not need to be forever. It only needs to be for some finite time that is larger than what would be expected of matter rolling down the energy hill towards equilibrium.
I do not see how this answers the objection. All you did was add the qualification ‘simple’ to the existing ‘external’. Is this meant to exclude fire, or include it? If the former, how does it do so? Presumably plant matter is a sufficiently “simple” source of energy, since otherwise you would exclude human digestion; plant matter also burns.
Again, which equilibrium? The star is nowhere near equilibrium with its surroundings.
Neither are humans… in a vacuum; but viruses are quite self-sustaining in the presence of a host. You are sneaking in environmental information that wasn’t there in the original “simple” definition.
Look at my reply to kalium. To reiterate, the problem is that people confuse objects with processes. The definition I gave explicitly refers to processes. This answers your final point.
I already conceded that it’s a fuzzy definition. As I said, you are correct that ‘simple’ is a subjective property. However, if you look at the incredibly complex reactions that occur inside human cells (gene expression, ribosomes, ATP production, etc), then yes, amino acids and sugars are indeed extremely simple in comparison. If you pour some sugars and phosphates and amino acids into a blender you will not get much DNA; not nearly in the quantities that it is found in cells. This is what is meant by ‘far from equilibrium’. There is much more DNA in cells than you would find if you took the sugars and fatty acids and vitamins and just mixed them together randomly.
I feel like we’re talking past each other here. I explicitly (and not once, but twice in the definition) referred to chemical processes: http://en.wikipedia.org/wiki/Chemical_equilibrium
Ok, chemical equilibrium. This does not seem to me like a natural boundary; why single out this particular equilibrium and energy scale?
I think you’re missing my point, which is that I don’t see how your definition excludes fire as a living thing.
I don’t think it does. A human in vacuum is alive, for a short time. How do you distinguish between “virus in host cell” and “human in supporting environment”?
Because the domain of chemistry is broad enough to contain life as we know it, and also hypothesized forms of life on other planets, without being excessively inclusive.
I tried to answer it. The chemical species that are produced in fire are the result of equilibrium reactions http://en.wikipedia.org/wiki/Combustion . They are simple chemical species (with more complex species only being produced in small quantities; consistent with equilibrium). Especially, they are not nearly as complex as compared to the feedstock as living chemistry is.
They are both part of living processes. The timescale for ‘self-sustaining’ does not need to be forever. It only needs to be for some finite time that is larger than what would be expected of matter rolling down the energy hill towards equilibrium.