Often, we call the stages of a star its “life cycle”, and I’ve been thinking about this for a bit.
Stars meet many of the requirements for living organisms: they can consume matter, they can react to stimuli (sort of, does gravity count? e.g. binary systems), they can reproduce (they expel gas clouds on death that can eventually create new stars), they can grow and change size over their lifespan, and they maintain equilibrium (between gravity and radiation pressure from fusion)
What stops stars from being considered living objects?
edit: as it turns out, the formation of new stars after death doesn’t really count as reproduction, and gravity shouldn’t count as stimuli (a rock experiences gravity too, but it doesn’t react to stimuli)
The generalization of the concept of “life” beyond earth-style carbon-based biochemistry is still in active debate. As far as I’m aware, the most consensual definition is the one called “lyfe” (to distinguish from the aforementioned carbon-based chemistry, a concept formulated by Stuart John Bartlett and John L Wong in 2020). It has four characteristics:
- dissipation : the ability to use/convert energy sources (arguably a thing that stars do)
- autocatalysis : the ability to grow exponentually (I guess you could argue it happens during the initial star formation before it reaches an equilibrium… Maybe)
- homeostasis : the ability to compensate for small disturbances in environment (unclear to me what those disturbances and what this adaptation would be in the case of stars)
- learning : the ability to record, process and adapt to information (no such thing in stars as far as I know)
they can reproduce (they expel gas clouds on death that can eventually create new stars)
I wouldn’t consider being eaten by a pregnant predator who then gives birth to be a form of reproduction even if I supplied resources to the born creature.
they can grow and change size over their lifespan
So can oceans but I don’t think it should count as growing.
They don’t react to stimuli like gravity any more than a completely inanimate object.
They also don’t reproduce. Dying and reforming is not reproduction. I’m not aware of anything already considered living that will die and reanimate.
I’m not aware of anything already considered living that will die and reanimate.
Tardigrades? They can cease any metabolic activity and then wake up years later as if nothing happened.
But that isn’t really reproduction, and not comparable to the death of a star
True I just wanted to mention these fascinating creatures because they are the closest we have to revival from death.
You’re already considering it, so the trivial answer is: yes.
The harder questions are: what do you mean by living? What do other people mean or understand by living? How does any particular definition of living help someone understand, communicate about and predict events?
Do they pay taxes? Do they dread the amount of trivial tasks to time ratio? Do they dream of electric sheep? Those are the three questions you should ask any entity claiming “life”
I believe them to be another type of “locally anti-entropic self-regulating systems” (for lack of a better term) which are parallel to life but not alive perse, just other type of emergent behavior. Stars do not have a metabolism nor a way of reprodution without destruction of the system.
My personal definition of life includes the propagation of latent information—meaning that a “child” inherits something from its “parent” that isn’t visible to an observer but that nevertheless affects its potential behavior.
Assuming we can see the size and chemical composition of the gas cloud out of which a star condenses, our current theory is that this completely determines the future behavior of the star. If that’s so, then the star wouldn’t be alive by my definition. But if there’s some unobservable quality that the star inherits from its parent and that does affect its behavior, I’d be willing to reconsider.
But why does it have to be unobservable? And if it is unobservable, how do you know that it is there?
We know pretty well and can observe that children inherit the DNA of their parents. And nowadays we also know that it is not only the DNA, but the epigenetic postprocessing that gets (at least partially) inherited. So according to your definition if we ever fully understood how bacteria propagate and behave, it would not be alive anymore?
Specifically, an organism has to keep latent information that’s unobservable to anything it interacts with (i.e., its ecosystem)—or at least, anything with an interest in predicting and controlling it. Otherwise, it has no guarantee of independent behavior, and it’s effectively part of a colony organism (or an organ of another organism). It also has no differential behavior for natural selection to act on, so it can’t evolve in a Darwinian sense.
To take your example of bacteria, we don’t observe and control the entirety of each individual bacterium’s behavior, but it has happened: it’s how mitochondria ceased to be independent organisms.
No.
