My gut bacteria may be vital to my survival, but they are not me. I don't find placing that line to be difficult at all.
Is it? Identity is an interesting thing. To use a commonly-cited example-- if I swap out the muffler of my car and toss the original in the backyard, I think most would say I am still driving the same car. If I do the same with the front left tire, it's still essentially my car. Even if replace all four tires, same. But what if I swap one part a day with a replacement, after a while I'll have all my original car parts in the backyard-- and am in effect driving a car made of totally new parts, but is this still the same car? If not, when would you no longer say it's the same car? And, if I assemble the collection of gradually discarded parts sitting in the back yard into another car-- now what? Which is my car? The thing I'm driving or the car made of the old parts? Or are they both the same car?
Am I really the same person I was when I was 10 ...or 10 months? What is the "me"-ness, or are we talking about a different person? Where's the line...
Or... when Captain Kirk uses the transporter-- his molecules are disintegrated, and then a copy of him gets assembled on some planet (using local materials I believe)... So is "he" transported, or is he being killed and replaced with an exact copy? (I think this question made its way to a Breaking Bad episode)
Anyhoo. Is a zoo without animals in it still a zoo? I dunno.
But yeah, is a zoo without animals still a zoo? Hard to say. Even without animals, a zoo would retain its potential to be a zoo. Meaning that you could put animals in it and would be back to being a zoo. Same thing can't be said about a restaurant, for example. You can put animals in a restaurant, but regardless of how good you can lock them in it's still not a zoo.
A zoo isn't a collection of animals - it's a social, financial, and cultural structure with associated buildings, signage, web site, and staff, that usually houses animals.
If you lose the animals temporarily, you can keep the rest and still have a zoo. (This has actually happened during wartime evacuations.)
If you lose everything, you have a former zoo.
We have minds that put simple labels on complex relationships.
So my response to your car example is that both vehicles are "the same car" since both get you around and both are owned by you.
In that sense, as your behaviour changes so does your identity. If you were able to 100% accurately encode all the actions you could ever take into a Markov Chain, then I would argue that Markov Chain is what makes you "you" at that point in time.
For example, at work I may keep to myself and be very quiet - in that setting my actions would define me as an introvert. With my friends I may be more outgoing and talkative, which is more characteristic of an extrovert. So I have two identities depending on my behaviour. I am not my introverted self when with friends, and not my extroverted self when at work.
Though to answer your question, "I" am an emergent phenomenon resulting from the interactions of the atoms in my body. "I" am just a wave passing through the universe, with my body as the medium of transmission. Similarly, "wind" is merely a description of what the air is doing where you are. As the wind blows, the specific air molecules you're observing as "the wind" are completely different from moment to moment, but a breeze persisting through an afternoon is all perceived as being the same wind.
So it definitely comes down to the definition. You would also be you if your brain were just in a glass with wires and you could process input and give output through a computer maybe without all the gut bacteria.
Doesn't the Star Trek transporter use the _same_ atoms/materials without making a copy?
A bit like a Lego house, you can break it up and you have all the parts to make a house, so it is potentially a house but it could also be anything else.
Indeed it could ;)
Parasites can also alter your personality. Perhaps they can even turn you into a cat lady/man.
What about during anesthesia, or deep sleep? (disregarding the certainty that you will wake up)
You could imagine a Ship of Theseus style replacement of all the neurons in your head with artificial ones. At what point would you stop being you?
Seeing as at least one episode of Star Trek dealt with such a thing, I wonder if any ever dealt with the possibility of a single individual with access to a transporter creating a continuous set of copies from the original scan, perhaps saving at intervals and allowing the instantiation of variously youthful or experienced copies to be made. The divergences over time in such a branching consciousness would make for an interesting sci-fi thought experiment, I think.
Sounds like a Zoo-Wannabe to me.
Human myName = new Human(mother, father, environment, spacetime);
Location birthPlace = myName.mother.getCurrentLocation;
location bithTime = myName.myMother.getCurrentBirthTime;
AssertEquals(myName, myClone) //false
I couldn't believe this was true so I looked it up. Apparently it really is! Of course the bacteria are on average much smaller and lighter than human cells. Also this:
>The numbers are similar enough that each defecation event may flip the ratio to favour human cells over bacteria
It's not so hard to imagine that the rules of relativity are imposed and that outside of that imposition, they don't exist or are discontinuous to some degree. Indeed, it doesn't even take any imagination if one considers the theories and research related to what I linked above.
So personally I'd dismiss the conclusion given its predication on this idea. To me, time not being local is the controversial position.
As if some not widely accepted recent papers without empirical verification are the ultimate source of truth in physics? All kinds of bizarro ideas are a dime a dozen in papers...
Well, specifically, proper-time intervals are path-local in General Relativity (GR). There is a unique coordinate-invariant proper-time interval between two points on a timelike worldline.
I think that extending that to "time is a localized phenomenon" is harder than it seems, notably because worldlines depend on the full solution of the Einstein Field Equations. In a Big Bang cosmology (with a hyperbolization of the EFEs and ignoring constraints and diffeomorphism freedom), it's pretty brave to deny a relationship between the early boundary and the values of the fields at any point p on the manifold given that the causal cone at p of M contains the Big Bang.
> effect that local gravitational force has on the passage of time
It's the metric that leads to Lorentzian observables between observers at different points in the manifold. The metric near bodies like Earth closely approximates that of Schwarzschild spacetime in the way it generates geodesics including the null geodesics (among others) carrying information from one observer to another. Effects like gravitational redshift arise from the fact that in spacetime more-curved paths are shorter than less-curved paths (as opposed to how curved paths are longer than straight paths through Euclidean space).
The metric's generation of geodesics is difficult to relate to a classical force or potential in general. Two objects in vacuum free-fall can be at different gravitational potential while feeling no force whatsoever; the one at higher potential ticks faster. It's a bit easier in near-Schwarzschild. Consider two atomic clocks falling from different altitudes towards the same point on the (practically atmosphere-free) moon; almost all observers will agree that the higher clock runs faster than the lower clock until they are both smashed together on the surface. Yet if each clock is equipped with an vector accelerometer, both accelerometers will point nowhere in particular with a magnitude of zero from the start of their free-fall trajectory until collision with the moon's surface -- the first time force is reported by the accelerometers is when "lithobraking" starts.
However, properly considering gravitational potential as a 4-vector generally requires some choices which eat the redundancies in the Einstein Field Equations. In General Relativity one has only the metric and Christoffel symbols and tedious arguments about which mathematical objects correspond to a Newtonian notion of a gravitational field (answer: "it depends" or "none of them"). Gauge-fixing lets one set a "depends" condition such that one can recover a vector potential field and a scalar field strength at each point; this approach is taken very seriously in Fedosin's covariant theory of gravitation for instance.
> effect that local gravitational force has on passage of time
Even if one takes steps to model some aspects of the gravitational interaction as a force, the proper time interval of an object doesn't change with the force acting on it. But the frequencies, lengths and related quantities of an object at some distance does depend on the force the object feels compared to the force the observer feels. (Moreover, if observers are in vacuum free-fall then they will feel no force at all, and can only infer the gravitational interaction from either a deviation from a straight-line track on a choice of coordinates, or by comparing the ticking rates of their own wristwatch with the wristwatch of several observer at some distance -- from [Synge 1960] this would take a minimum of five freely-falling wristwatches in total).
Generally the complexities of setting down this kind of gauge-and-coordinate conditions leads relativists away from worrying about relating GR's mathematical objects and Newton's, and it's easier to say "gravitation is not a force" rather than "with some effort you can treat gravitation as a force in local coordinates and in a local gauge but you'll still find yourself returning to the Special Relativistic forms of physics equations because they genuinely are the simplest form and are always valid in the neighbourhood around a point on a geodesic".
> if one considers the theories and research related to what I linked above
General Relativity is in extremely precise accord with observation at many length scales and
direct experiment within the solar system. Deviations from General Relativity that are different in the limit of the parameterized post-Newtonian formalism (which applies at solar system scales) are almost entirely ruled out. Although it is perfectly reasonable to consider General Relativity to be an emergent theory, the theory it emerges from is (a) unknown (b) unobvious and (c) extremely difficult to take guesses at. Indeed, your offer of 1310.4691 is wholly rooted in this: canonically quantized GR conflicts violently with observations and experiments, and the usual workaround is to do some condition-fixing (which your referenced paper does) and then to try to get around the pseudo-forces brought in to describe local physics (in models like Page-Wooter these pseudo-forces appear as constraints in the theory (, which your authors reference in their first sentence and several times thereafter). The paper you point to also notes that the proposed experiment cannot select among a number of theories including General Relativity (where the Hamiltonian itself is a constraint).
> To me, time not being local is the controversial position.
I dunno, we do appear to live in an observable universe which admits an obvious equatorial 3+1 slicing in which there are an awful lot of Eulerian and nearly-Eulerian observers. Is the hill to die on the alignment of one's "natural" choice of timelike axis with the metric expansion or the way you put down coordinates on that axis? And how do you square either of those choices with the initial value formalism?
 This is implicitly fixing a gauge wherein the surface of the moon is special; this is analogous to having a set of tunable air-pressure gauges at a point at sea level and setting it to 0 there, then using the readings of the tuned pressure gauges in helicopters riding above one another over the 0 point in order to say things about the state of each helicopter. In particular, one would use the reading of the pressure gauge as the basis of a coordinate axis (e.g. in marking coordinates on the radial axis in spherical coordinates on the 0-calibration point, or on the z axis in a choice of Cartesian coordinates on the 0-calibration point).
 K. Kuchař, in G. Kunstatter, D. Vincent, and J. Williams (eds), Proceedings of the 4th Canadian Conference on General Relativity and Relativistic Astrophysics, (Singapore, World Scientific, 1992).
Indeed, you can consider the universe as this thing which is maybe boundless and has so much stuff and might go on forever but for some reason you think it's any harder than realizing that the street may be infinite in space as well, by virtue of continuous subdivision. Before trying to dive in on any estimate of the smallest thing, do remember that smart people once thought atoms were the smallest thing, and then particles, and so on. And remember that the street itself, even just the stretch you're concerned about, is composed of a ludicrously large number of the "smallest" things we current are aware of.
If we let go of this idea that at our own size, things are just some number of things that we can reason about (since that's clearly false, do you reason about the billions of living organisms in your own body right now? Could you?) then we can start to realize that smaller or bigger, we're merely consider a continuum at different scales and it's perfectly reasonable for the human mind to do so, it does so every day all the time.
Understanding is just a psychological phenomena. Its your brains who choose what ideas they mark as 'understood'. Thus its under your control what you understand and what you are not.
Once beeing a drunk teenager I felt myself understaning all the things in the whole Universe. Its pretty hard I'd say, because I never felt like this thereafter. Though I didn't tried to repeat it. Probably alcohol is not the best fit for it, maybe there are some drugs that can make you to understand.
I believe that somewhere in the brain there is some special spot, and all you need to understand everything is to thrust an electrode in that spot.
If you live your brain as I do and prefer not to control your brains in possible harmful way, than (I'm pretty sure) if one get some special training on this he could come eventually to everything-understanding state of mind. Maybe it even allow to switch by volition between that state of mind and state of mind of Socrates, who used to claim that he understands nothing. I didn't try it myself because I'm not sure about arbitrarily control option, and generally prefer Socrates' way of thinking.
But if you don't like to cheat, there is honest way to start understanding a very large distances. In general mind mark as understood all the things it is used to. You may train yourself at imagining large objects through some sort of succession. You should do all sorts of mental work with those objects in your imagination -- moving them, rotating, colliding, flying by or through them... Try to use different and constant kind of objects for every order of magnitude -- it might be really helpful. It will take time, but its still possible.
There is no physical barrier stopping you from moving in any direction, but due to the shape of the Earth you have reached the southernmost point.
It is likely the same with our universe, and its inherent morphology, too.
There's one at the Big Bang. You can go through contortions to try to remove it (Hartle & Hawking's "no boundary proposal"; Carroll & Chen's "two-ways-to-de-Sitter from arbitrary initial surface") but so far attempts have come at the cost of introducing a lot more conceptual baggage.
"more of mostly the same" unless you think that one metre or one light year or two hundred million light years beyond the Hubble radius the universe is vastly different from the stars and galaxies we have around here. What could have happened to early galaxies that 200 million years ago were in principle observable from the Milky Way, such that they wouldn't now resemble the descendants of early galaxies that are 200 million light years closer to us?
My high school physics prof had the best answer to "What is beyond the universe?" --> "Surely if we ever find something outside of the universe, we will be smart enough to call that the universe too"
He was referencing the idea that universe contains everything by definition.
Universe is our local observable space-time with the earliest event we can detect being the big bang.
So if we observe something beyond what is currently observable, would that not become observable and thus part of the universe?
For now we're stuck in our universe, we know it's expanding (in something, potentially). So we preemptively give the name "cosmos" to EVERYTHING. It's entirely possible that cosmos is equal to universe. But it's also possible there are other universes out there, or something entirely different.
Transitivit would say yes. If A implies B and B implies C then A implies C. That is, if you can observe A and that implies B, then you can observe B. Which makes it observable, no?
But you would still have something just as remarkable.
It seems to indicate that for a thought to happen, a signal must traverse the entire length (width?) of your brain.
That isn't how it works at all. Many thoughts are localised in the brain. Further, some signals don't need to get to the brain at all. And some functions of life don't even need signals to ever leave the localised region at all.
If you are cut, your blood cells spill out, clot, and prevent further bleeding from happening, all without anything outside of the immediate vicinity of the cut to be notified (although it's good to let other parts of the body nearby, say another finger, from exacerbating the wound).
If the organism were larger than say a planet, then why would not the brain become distributed, with the parts needed to deal with one quadrant of the planet located at that part of it?
Basically, this article is lazy. It makes a couple of very dubious assumptions, then runs full-forward on those assumptions, never stopping to think if those assumptions even make sense.
Yes, if we are to try to imagine a life form that looks exactly like a human (or other life-form that we find on Earth), but is the size of the galaxy, we start to laugh, because that couldn't work. But that thought experiment is pretty silly.
Don't humans to a degree fulfill this role; the mass behavior of the species (recently) acting as form of brain with emerging self-awareness of the galaxy/universe; since we study it, and are also part of it?
Behavior can be influenced by others, but will isn't superceded by a crowd.
It often is by governments though. Also judging by polling on small sample sets, which often match whole population elections they do coherently aggregate; and then those governments make laws which incarcerate or penalize going against them.
Also isn't that the nature of science to provide coherent aggregation of knowledge that is agreed upon (though testable hypothesizes). Which is generally different from government policy, which usually doesn't use evidence based decision making in the scientific sense.
So yes, a universe sized lifeform could not have evolved randomly since the big bang, but you can only be confident about that if you assume that nothing exists outside the spacetime bubble we call the universe.
It's fun to kick around crazy ideas on Saturday afternoon. It could be anything. Sadly, there's no way i'll ever know. But the idle speculation is still amusing.
Does it really make sense to talk about it as being a single organism? How could it do anything in a coordinated way?
Or how about an organism that grows at say 10m in diameter per year, but signals across its body only propagate at 1cm per year? Again, how can it be considered to be functioning as a discrete organism? Surely if such a being evolved, its parts would perforce do so independently of each other? There could be no cross-organism coordination. It would have to disintegrate or devolve into local functional or operational units if it were to do anything effective at all.
Ae could be in it's stomach, where processes slow down the speed of light by a factor of trillions so that we are easier to digest.
None of these are testable hypothesese of course. But one day they may be testable.
This particular nasty swipe is not only not ok on HN, there's a specific rule against it. Please (re)-read https://news.ycombinator.com/newsguidelines.html.
The size of the observable universe: ~93 billion light-years
Time since the big bang: ~13.7 billion years.
That doesn't mean he must be right, but I feel pretty comfortable citing him.
The whole article is predicated upon a bunch of faulty assumptions, it's like it was written by a simple minded child.
Your comment doesn't really give accurate credit to the current state of knowledge.
Yes, quantum entanglement doesn't seem to allow for transmission of information in the conventional sense. However...
Take a universe full of particles, many of which are entangled with each other. If you consider the entanglement as primary you can think of the entangled particles as single entities that have "extensions" into space-time that can be widely separated. I don't think it's at all clear that "living" processes cannot be carried out on this "substratum" of interspersed non-local entities.
But I'm waaaay over my head here, so I'll stop waving my hands. :-)
If I send you to a junk yard and say "Find my old microwave" can you do it? You'll probably start by looking for things that look like what you think a microwave looks like, right? But what if mine looks different?
We know life is probably somewhat rare in the universe, at least compared to the raw number of planets. But we know that Earth ticks all the right boxes to generate life, despite that adversity. So we look for things like Earth because it's more likely to be productive than a blind search with no bounds.
Yes, see: http://www.xenology.info/Xeno.htm
Life on larger, slower scales rapidly hits the problem that 15 billion years turns out not to be all that long when you start dividing it by thousands or millions at a time. The problem is that if you're spread out that far, you're probably mostly running at the ambient temperature, which is very cold and much slower, so not only do you need to take 3-6ish orders of magnitude of speed off for dispersion in space, you need to take 3ish orders of magnitude off for being very cold and thus chemistry being very slow. And you may need to take another 3-6+ orders of magnitude off for waiting for your very dispersed, very cold molecules to encounter each other at all, in order to do whatever reactions are supposed to be supporting you. The problem you have there is that on that time scale, the galaxy is a very active and violent place, with supernovae popping off and galactic collisions and passages through the arms and all these stars flying about far faster than you can react to them (rather than the stately procession we think we see) and all kinds of things that tends to make a sensible person thinking about this problem starting thinking that even were some magical force to create such a life form, it wouldn't subjectively live very long before being violently destroyed from its point of view.
(And there are really quite a few more factors missing from the story of how one could have such an enormous life form, like how one forms from what are, to a first approximation, hydrogen atoms with trace contaminants. The biggest "contaminant" also happens to be helium, which you're not going to be doing much chemistry on. Seems difficult to imagine what "chemistry" would be going on here. (And if you want to say "energy being", be concrete about what sort of energy it is you are talking about, and how it manages to accomplish any sort of reaction or computation. It turns out that at least in our universe, "energy being" is probably just a nonsense phrase with no possible physical referent.))
I wouldn't write the idea off perhaps as entirely as some people here have, but if such large organisms or civilizations are going to ever exist, they're going to have to exist in a later epoch of the Universe, i.e., they're still many, many billions of years in the future. Right now the universe is too young and vibrant and explosive for anything like that to exist for very long.
If these sorts of things intrigue you, and you'd like a semi-realistic treatment of some of the similar ideas, you might consider https://www.youtube.com/watch?v=Pld8wTa16Jk . The boundary between "science fiction" and "the optimal possible engineering" is fuzzy but that video does a decent job of riding the line. One of the things I don't think he mentions is that some of the "slow" civilizations he mentions, where a thousand years literally pass like a single thought, is that they might be geographically dispersed, for at least some of their components, on this scale. As you hypothesize beings or civilizations (and honestly, from where we sit, there isn't necessarily that great a difference between the two things) that exist orders of magnitude more slowly than we do, the speed of light stops being such a bummer and "virtually" speeds up.
However, I see no limit to the size of zero-gravity organisms like the honey fungus. Fungi are filamentous, so there's no unsurmountable problem with heat dissipation.
And even for self-conscious organisms, I can imagine hierarchical organization, such as Rajaniemi's "metaself" or Watts' Bicameral Order.
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 much, much smaller (as it usually happens in biology) would be longer than the age of the universe.
Another one is that nerve impulses travel slower than the speed of light, and so, again, it would take forever for a signal to reach the central nervous system. One could argue that the creature can be "decentralized", i.e. look more like a large colony of smaller organisms, but then the question arises as to what makes it a single creature in the first place.
Yet another issue concerns what drives the evolution of this particular species, and, again, the time it takes.
So far, all these considerations unavoidably lead to the answer 'no'.
Reasoning about much large systems than our own is difficult. Imagine a bacteria attempting to reason about a human - the existence of fluid transport and centralized heating may seem a bit odd, as bacteria have developed to solve an entirely different class of problems at the organism level.
I don't get why nervous systems should be brought into the discussion. Most living beings on Earth do not have any kind of nervous system, and I don't see any obvious reason for why fungi or plant-like life forms could not be as big as galaxies.
> Ctenophores have no brain or central nervous system, but instead have a nerve net (rather like a cobweb) that forms a ring round the mouth and is densest near structures such as the comb rows, pharynx, tentacles (if present) and the sensory complex furthest from the mouth
Ctenophore nerve cells and nervous system evolved separately from other animals and have a different biochemistry.
> From a physics perspective, living beings are thermodynamic systems with an organized molecular structure that can reproduce itself and evolve as survival dictates. ... A major strength of this definition is that it distinguishes life by the evolutionary process rather than its chemical composition.
Incidentally, a galaxy-size dense environment (and the creature itself) would collapse into a bunch of stars and black holes "in no time".
What makes you say that, though? I don't see any reason for it. Some ethereal galaxy-scale lifeform might be thinking as well that "life cannot exist in the extremely hot, hyperdense environment of a planet" for example. This is pure speculation from your part.
"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 survive you are no longer alive and thus not living. We've then defined a state where a living being must continue living to be living, well sure - I agree.
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 more for lower level life forms, where is not clear (see viruses).
Higher forms of life could be defined differently - agency, ability to sustain/repair itself, opposition towards environment. But then you might encounter difficulties with classifying a self repairing (non-sentient) robot as "alive".
According to Darwin, it does. A giraffe got its long neck not by stretching it but by dying if the neck was not long enough to survive and letting the ones with (accidentally) better genes to live on and - importantly - reproduce.
I don't know what is left, but I have a hard time using such an embattled definition.
A multi-cell organism is an emergent phenomenon that helps protein-based molecular structures to do their thing ("life").
I've said this elsewhere, but proteins are not required, in any regard, for life. They are an emergent phenomenon of the Earth's chemistry, not a rule for life. I mean, what is a cell even - "A fluid filled, membrane enclosed thing"? The reason cells are structured as they are is because of water, so a non-water based organisms would likely look much, much different.
I am not sure I understand the drive to redefine life beyond the life as we know it (i.e. what it actually is, as a fact), the drive that leaves one in what can only be seen as the domain of fiction at best (and pseudo-science at worst).
Does intelligence imply life? I'd say no.
Signals in the human body do not arrive instantaneously. A life form at the galactic scale would either be decentralized as others have suggested, or it would operate at a much longer time scale.
Personally, the last few years, I have felt that working to understand how all phenomena can be sketched out on the log scale has helped me gain a deeper understanding of the world. Of course, this goes hand in hand with related ideas, such as having a generally skeptical mindset, seeking first principles, etc.
These ideas has been very powerful for me, and I thought it might be worth sharing.
P.S. the book "The Black Cloud", mentioned in the article, is a really fun and quick read. I recommend it for any sci-fi fans.
From Star Maker by Olaf Stapledon, Chapter 11, Stars and Vermin
Perhaps certain parts of the brain too "think" they are conscious but can't individually experience the same consciousness we as people experience.
It doesn't make much sense for a creature the size of the galaxy. If it did, it would be extremely slow and alien to us.
A more plausible way would be if a human-scale civilization would create self replicating probes that would spread in the galaxy and bootstrap some sort of large biological or AI civilization.
If yes, the next question might be:
> Imagine a creature that is as big as the galaxy, imagine its organ that is analogous to our brain is as efficient and big as is possible, what is the most complex concept that that brain can fully comprehend?
Given the nature of evolution, and that one subscribes to it, life on Earth started with a single organism that replicated. From that point until a replication modified the organism into a different species, there would have been one species. But was it necessary to have multiple species in order to sustain life?
It's a kind of feedback loop in low-entropy systems that given enough time can produce interesting phenomena, including this message board.
I would tend to ponder that life in it's simplest form is not singular and never has been and this is the cause of evolution.
This doesn't mean it was the only origin of life on Earth, but it is the only surviving line.
It also took a few days for complexity to arise. About a trillion of them.
"Available evidence", because there are no extant lifeforms which diverge from the known set of amino acids, no prokaryotic life which doesn't have (or at least didn't once have) mitochondria, utilisation of the Krebs Cycle, and numerous other elements.
Again, other variants might have emerged. But they haven't survived, suggesting the extant line out-competed (or possibly out-lucked) any challengers
It is certainly more insightful (again imho) than this article.
(Geoffrey Landis, the Melancholy of Infinite Space)
First off, single organisms can have pretty advanced local processing of control. An octopus has a nerve cluster for each tentacle that can operate independently of the main brain . So in at least one case, biological brains delegate work out to another region of the body. An argonaut octopus actually detaches part of it body, which as far as i can tell, keeps living for a while. it's kind of creepy. The only thing i can't find an example of, is remote control. A detachable body part, with a nerve cluster, that responds to light or sound seems like what would be needed for the base creature. Evolution hasn't stumbled on that trifecta here on earth. But it sure seems like something that could have come about.
The latency argument isn't compelling. If i can send one message, i can send another hundred billion messages along with it. So, sure only a few thousand round trips, but a fabulous amount of information transferred. There's no actual biological equivalent to a semi autonomous drone, so i'm not sure what that would look like before the creature took to the stars.
There's also no real obvious way for this lone detatched tentacle to consume the resources of a planet. But whatever. I think one entity with those three features might have a chance.
Also, is the creature smart? Does it get to genetically engineer itself? do cyborgs count? That greatly simplifies things as well. The detachable parts could have detachable parts, and recurse down to whatever arbitrary degree is useful.
Alternatively if you admit superorganisms, then everything is much easier.
So anyway, you don't really need to send many messages when the message is "here are the latest designs for industrial architecture to dismantle a solar system and send the resources back" It's up to the billions of lone tenticles and their machines to execute the will of the super brain.
On the other hand, yeah, there's not going to be a galaxy sized amoeba or panther or anything like that. maybe an incredibly fine mist of fungus or mold, but i think it'd be too hard to keep a system like that from collapsing in on itself from too much mass. a galaxy sized ring of spider silk orbiting a black hole sounds like great science fiction. but i can't imagine that working.
So no, you could not have a living creature as big as a galaxy.
Sometime go look up the amount of space between the protons, neutrons, and electron cloud in an atom.
Superluminal, or faster than light, communication is said not to work because it allows information to be sent into the past. There is however non-locality which is not the same thing. Sorry not an expert on this, but this seems to apply to the exact discussion.
There's no such thing as "quantum phenomenon" that is distinct from any other phenomena. All phenomena are quantum. You're using that word the same way any other woo-peddler uses it: to worship ignorance and preserve the 'majesty' of the unknown.
This sounds rather reductionist. (I am not sure if all "physicists" are prone to making this mistake.) Surely, the French Revolution was not a quantum phenomenon.
The article here is the one that is making an unfalsifiable claim that "a living creature cannot be as big as a galaxy", but offers no definitive proof of nonexistence of such creative.
The classic example of white swans and black swans adheres to the problem of making universal generalizations because we simply have not yet observed a black swan, and we cannot use the continued observation of white swans as empirical evidence. However, we are not attempting to make a universal generalization based on inductive reasoning.
We have, available to us, a schema for enforcing the testability of this claim, which the article and its references explore in detail. The square-cube law and our current model of physics both make it impossible for a "living creature" to be as large as a galaxy, for any definition of "living" and "creature" that is reasonably agreeable.
The normal processes of life; including temperature regulation, metabolism, energy expenditure and movement would all be severely impeded in a single discrete organism of that size. Moreover, it would have severely limited cognition even if signals traveled at the speed of light, which handicaps both its own sophistication and potential evolution.
It doesn't seem appropriate to characterize something that cannot have these functioning traits as "living"; the only way forward seems to be to broaden our definition of "living" or "creature" to some sort of aggregated, abstract consciousness that makes organisms like ourselves analogous to bacteria. But that can hardly be called a discrete organism in the same way that our brains are cognitively independent of the life around them.