Hypnosifl

It might be related to the fact that the Doc at the end of the movie is from an altered timeline and remembers Marty visiting him 30 years ago, while the Doc at the beginning of the movie, the one who mentions possibly going ahead 25 years, hadn't had that experience. The altered Doc might like the symmetry of going ahead 30 years just as Marty went back 30 years.

@RobertRapplean - But you haven't answered my question whether you think this model can accurately reproduce the input/output behavior of actual biological neurons, as opposed to some simpler system that is broadly neuron-like in the sense of using sodium channels etc.

@RobertRapplean "Mathematically" doing what exactly? Are you claiming this simple code can accurately replicate the actual input/output relations of real biological neurons, the way the much more complex simulation I linked does, or are you claiming that this isn't necessary, perhaps because you think neurons evolved to perform some much simpler "logic function" and that any additional complexity in their real-world behavior is just useless noise that plays no important role in their functional role in the brain, so it doesn't need to be captured accurately in an artificial substitute?

@RobertRapplean What do you mean by "essentially"? Do you mean a much simpler program simulating an "integer weighted moving average calculator" could accurately reproduce the input/output behavior of a real biological neuron, or that accurately reproducing this behavior wouldn't actually be necessary for a simulated brain that reproduced the higher-level behavior patterns of the biological brain it was based on (i.e. that an integer weighted moving average calculator would suffice for this even if inaccurate in its details), or something else?

@JBH "And the theorem is, at best, wishful thinking until we actually build something beyond a quantum computer prototype" A quantum computer is not actually necessary, since a classical computer can compute all the same functions as a quantum computer, it would just require a lot more time and components. Once we grant an exact physical simulation of any finite system would be possible in principle on a classical computer, one would expect it's likely that approximate solutions would suffice for reproducing high-level behavior, like the neuron simulation I mentioned in my other comment.

@JBH - von Neumann didn't say the only way to simulate a complex system is the system itself, rather that this might be the simplest way. Most natural scientists take it as a default hypothesis that the behavior of any system is in principle explainable in terms of the interaction of simpler components ultimately going down to the level of quantum physics, and there is a theorem that any finite quantum system can be simulated on a quantum computer.

@RobertRapplean - Why do you think we have the processing power to simulate a brain now? This article suggests the computational complexity needed to simulate the responses of a single neuron are actually fairly high, and looking at the paper, it looks like they were focused on input/output at the msec level, I don't think they tried to simulate further complexities like neuroplasticity due to changes in receptors/dendritic growth.

@ToddWilcox I think it's reasonably clear that the paragraphs on Star Trek and Dune were just meant to show analogous cases of sci-fi universes with advanced tech but which are missing some seemingly simpler classes of technology we have today. The question is whether there is anything similar in the Star Wars universe. Whether this question is too "opinion-based" seems to me to itself be pretty opinion-based, it seemed straightforward enough to me so I voted to reopen.

@AcePL When you say you added context, do you mean your own comments about salvaging supplies and about not going in a straight line at any enemy ship? If so I think it would be helpful to put in some quotes (from the section of the book involving that same 0.2c trip) that demonstrate this context with some explanation of how it relates to paths, as you said you're free to put this in spoiler tags or just say something like "the quotes below contain spoilers".

I just realized you weren't using the fact about the canon acceleration to conclude it takes 60 days to cross the solar system, you just took that figure of 287 light hours and divided by 0.2 light-hours/hour to get 1435 hours which is 59.8 days. But is 287 light hours stated as the distance they were traveling in that section of the book, or are you using it as the size of the real solar system? If the latter there are a variety of definitions that could be used for size of the solar system--were you defining it in terms of the diameter of the inner edge of the Oort cloud?

When you say "first example" do you mean the first quote in the OP (which doesn't mention stopping at planet or salvaging supplies), or other text in that section of the book (in which case it would be helpful if you would quote it), or something else? Likewise, could you quote what they say about max acceleration and time and distance? Are they talking about the time to travel 1 light hour if they start accelerating from rest? If so that doesn't mean subsequent light-hour intervals will take the same time to traverse, since the ship already has some large velocity when it starts them.

I don't think the scenario in the OP involved stopping at planets, did it? If we're just talking about gravity boosts during flybys, I don't see how "real life" is separate from physics here--if the physics here says that a gravitational boost from flying by a planet at 0.2c could only affect your speed by some miniscule fraction of that, say boosting it to 0.2001c, then presumably that would mean a similarly miniscule amount of fuel savings, no? Also, where do you get 33 days? Going from one side of Neptune's orbit to the other would take about 1.74 days at 0.2c.

(though I should add that the relative size of the central star would be different if it were something like a red giant or blue giant/supergiant--it's predicted that when our sun goes into its red giant phase, its surface will expand at least as far as Earth's orbit)

Incidentally, on the issue of needing to plot a course around the sun/planets, the vast majority of a planetary system is going to be empty space so it's very unlikely a random path between two points in that system would intersect the sun/planets unless there was specific reason to expect it to (like a path between exact opposite sides of the sun). See this article--if the sun were scaled to the size of a basketball, the Earth would be a tiny pellet about 86 feet away, Neptune about half a mile away and less than half an inch wide.

Are you saying jump points are typically on directly opposite sides of the sun, so the shortest path would go through the inside of the sun? If not, just the fact that they are the same plane of the ecliptic wouldn't seem to be sufficient to conclude the shortest (geodesic) path between them would go through the sun. And while gravitational slingshots with planets may be useful for speeds of real space vehicles I doubt they would be much use for something moving at 0.2c, or shift its path to a degree noticeable by human eyes (see my comment on the OP about the tiny deflection of light by sun).

Is this answer based on things said in the text, or are you just arguing that realistically a ship would use curved paths to conserve fuel when getting to some destination in a planetary system? If the latter are you talking about gravitational slingshot maneuvers or saying curved paths would be needed to conserve fuel for other reasons? The part at the end about not traveling on straight line paths on Earth seems like a non sequitur, you go on curves because you're traveling along a curved 2D surface and can't burrow into the ground, how is that analogous to moving freely in 3D space?

@fredsbend - I agree with the OP that this issue is irrelevant to the question, but since you say "Banks didn't mean for it to be" utopian, see this interview where Banks said "it’s my secular heaven. It’s the best I can think of in terms of something as close to a genuine utopia as it’s possible to get, and in many ways it is a utopia. It’s not absolutely perfect, but it’s as close as you’re going to get with anything remotely like us, if not in charge, then involved."

@fredsbend - It's not a pacifist utopia (nor was Thomas More's original Utopia), and it didn't have anything like Star Trek's prime directive, but it seems to me that Banks largely did think of the Culture as a fairly ideal society that was actively trying to push other surrounding societies to rid themselves of various kinds of oppression and other causes of unnecessary suffering that weren't present in the Culture. And sometimes those "pushes" would be seen as requiring violence, and that was the type of scenario the books would tend to focus on for dramatic reasons.

@LogicDictates I entered the link into archive.ph and found that someone had archived it before it was paywalled: archive.ph/TCGgp

Descartes definitely wouldn't have draw any certain conclusion from the premise that he perceived something. What do you mean? Isn't the Cogito based on the fact that he consciously perceives his own thinking, so he thinks that leads to the minimal self-evident conclusion that a thinking "I" exists? Without conscious perception of thought it would not be self-evident that thinking is taking place.

To understand what people say, we start with the standard use of the language If a claim requires assumptions derived from "standard use" that are not self-evident from a more philosophical perspective, then the proposition cannot itself be self-evident. For example, in standard use if we read an "I" statement we assume that refers to a human being, but Descartes' Cogito is supposed to be stripping away everything that's open to doubt philosophically, so he wouldn't treat something like "I think, therefore a human being exists" as self-evident.

The fact that a term exists in natural language doesn't imply it's a coherent possibility (consider the term 'square circle' for example). There is certainly a widespread popular understanding that asserting that something exists is distinct from asserting that it is consciously perceived, but Berkeley's philosophy shows it's possible to doubt this is actually coherent, that we literally can't imagine anything that isn't a type of perception. So if Descartes' Cogito relies on the implicit assumption that existence and perception are distinct, it can't be seen as self-evident.

No, but the question I asked is whether the Cogito relies on the implicit presupposition that we know what words like "being" or "exists" mean distinct from perception, and if so whether Berkeley's argument shows that this is not actually self-evident, even if you grant that some kind of perception is self-evidently taking place when you have a thought.

Not sure what you mean by "different logical expression" here since logic deals only with the logical form of a statement, not the semantic meaning of the terms--would you say "John is an unmarried man" is a different logical expression than "John is a bachelor", even though "unmarried man" and "bachelor" are understood in English to be synonymous terms? Berkeley is making a philosophical argument about the meaning of the term "being", that it is implicitly synonymous with perception and that the belief that they are non-synonymous arises from failing to think carefully enough about them.

Does the claim presuppose that we have some meaningful notion of what it means for something to "exist" separate from it being consciously perceived? Berkeley's idealist philosophy seems to collapse the distinction between existence and conscious perception ('esse est percipi', to be is to be perceived), and he argues we cannot even assign meaning to any notion of non-perceptual existence when we examine the notion carefully, so I wonder if the cogito would just become a tautology like "the thought is perceived, therefore it is perceived".

@FlatterMann - I never said anything about the state of the universe being "knowable", just that there is some truth about the state even if it is unknowable by any conscious entity. This is a straightforward assumption of most materialists, it seems like a far more "supernatural" concept to imagine that the only truths are those which are known by conscious beings (in philosophical terms this would seem to be a form of idealism).

@FlatterMann -- So you disagree with the common theoretical idea that there is some complete state of the world at any given time, even if we humans don't know it? If so what reason would you give for thinking the idea is wrong? Think in terms of the hypothetico-deductive mode of evaluating theories--under the hypothesis that there was such a complete state, would your human observation of experimental results under incomplete information be any different? If not you can't really take these observations as evidence against the hypothesis?

BTW, I think @AnduinWilde is misstating the conclusions of the authors in saying Newtonian mechanics is "near Markovian", in Newtonian mechanics one can have instantaneous velocity vectors that are viewed as intrinsic parts of the state of the universe at a single moment in time, and this is what the authors are alluding to when they say "all of our best physical theories are compatible with being Markovian, perhaps subject to debates about whether certain vector quantities are intrinsic to a time or not".

And note that although this issue may have philosophical implications, the problem as I stated it in terms of conditional probabilities is a physical one, we could dream up hypothetical laws of physics where P(E | S1 and S2) actually was different from P(E | S2), but our best physical theories so far don't have this property, they are fully "Markovian" in the sense the authors of the paper use the term.

@FlatterMann - The question is whether the state of the world five minutes ago changes your prediction of future dynamics if you already know the state of the world right now. In other words, if you want to know the probability of some future event E and know both the complete state S1 of the world five minutes ago, and the complete state S2 of the world now, is P(E | S1 and S2) ever going to be different from P(E | S2)? If not, that shows S1 is only causally relevant in terms of its influence on the later state S2, there can be no causal effects on E that are due to S1 but "leap over" S2.

This argument seems to be based on the contingent linguistic fact that "free will" is both a term for a A) subjective feeling of decision-making power, and B) a metaphysical doctrine that one's decisions have no prior causes. There is no logical connection between the two (why shouldn't a deterministic being have a feeling of decision-making power?), nor any good argument that "free will" in the experiential sense should be considered evidence for "free will" in the sense of the abstract metaphysical doctrine.

@user4894 - Also, the Seth Lloyd paper you link to is talking about a different issue--if we have multiple algorithmic formulations of the exact same laws making the exact same predictions, can we know if a given formulation is the shortest possible algorithm in this class? But if you don't care about the concision of the formulation, only about making correct predictions, his paper presents no obstacles to that.

@user4894 - The evidence Deutsch gives is that in quantum theory, any system whose state can be described with a finite amount of information can be computed perfectly by a quantum computer, and on p. 13 he says it's an open question whether every system in a finite volume does have a finite quantum state, but mentions a strong theoretical argument that this is the case: the Bekenstein bound which is needed for black hole thermodynamics to work (and there are other lines of theoretical argument that also converge on this bound).

@user4894 - The laws of physics themselves are likely computable, meaning the behavior of all physical systems follows laws that could in principle be simulated on a sufficiently powerful digital computer. If this is correct, then humans, like any other system, could be said to be "programmed" by the laws of physics plus physical conditions in the distant past (shortly after the Big Bang, say).

Compatibilist free will is often understood more in consequentialist terms--categories of situations where some kind of social disapproval or punishment is more likely to change behavior are considered to involve greater free will, categories where they're less likely to change behavior are considerd to involve less free will. For example, disapproving of behavior people do when suffering delusions that impair their rationality, or behavior they do when someone is making terrible threats (holding a gun to their heads etc.) would be seen as involving less free will for this reason.

Are you asking specifically about libertarian free will, rather than compatibilist free will? If so you might want to specify that in the question.

@MoziburUllah And it also quotes Plutarch clarifying what Democritus meant by "necessity": "Democritus says that it is impact and motion and a blow of matter." And Eusebius derides Democritus for his rejection of free will, saying that Democritus "has it in mind to show that the noblest of human things [i.e., free will] is a slave."

@MoziburUllah Some of the support for this given in the book is Aristotle's comment (p. 93) that "Democritus neglects the final cause, reducing all the operations of nature to necessity." That page also quotes Cicero saying Democritus "preferred to accept that everything happens of necessity, rather than to deprive the indivisible corpuscles of their natural movements, as Epicurus did."

@MoziburUllah The earlier atomists like Leucippus and Democritus also seemed to have believed everything happened by "necessity", ruling out "chance" as well as later concepts of "free will" (though Lucretius introduced the notion of an unpredictable 'swerve' in atomic motion, in part to allow for free will, an idea adopted by Epicurus). The evidence for this doctrine is discussed at length in a section starting on p. 188 of Taylor's book "The Atomists: Leucippus and Democritus".

@MoziburUllah Presumably "soul" would just refer to the animating element of living organisms and wouldn't involve any dualistic Cartesian notions of mind as metaphysically distinct from matter--if Democritus learned of later results of electrochemical impulses in nervous tissue leading to bodily motion, he might well say that this just pins down the "soul atoms" as being the ions and neurotransmitters whose motions make up these impulses.

he says that that the spherical ones compose fire and the soul (like the so-called motes in the air, which are seen in sunbeams coming through windows)".

@MoziburUllah According to contemporaries Democritus did not say each of us has an individual "soul atom", rather that the soul was composed of atoms. For example Aristotle said "some say that the soul is chiefly and primarily the cause of motion, and as they believed that what was not itself in motion could not move anything else, they conceived of the soul as something in motion. Which is why Democritus says that it is hot, a sort of fire; for while there are infinitely many shapes,

@MoziburUllah "Your idea that real physicists take any serious notice of timelike loops and acausality is frankly not true" It depends what you mean by "serious notice". Obviously many physicists might have strong intuitions that such things will not turn out to be possible in a final theory of quantum gravity (I share such intuitions myself), but that's not the same thing as taking a non-mathematical "principle of causality" as some sort of a priori truth that rules them out absolutely.

@MoziburUllah "The ADM formulation of Hamiltonian GR relies on time evolution" The ADM formulation is a way of reformulating GR only in the case of "globally hyperbolic" spacetimes, see here for example. But there are valid solutions the field equations of GR that are not globally hyperbolic so the ADM method can't be used, and spacetimes with CTCs are examples.

@MoziburUllah "I've already pointed out that Hawkings Chronology Conjecture is based upon a long-standing implicit physical principal of causality" I've already pointed out that Hawking's paper describing the conjecture makes no reference to a "principle of causality", only to specific results in quantum field theory in curved spacetime, and that he himself treats CTCs as a viable possibility, and you presented no counterargument, so this claim is clearly completely unfounded.

@MoziburUllah In other words, if we use the hypothetico-deductive method, both a hypothesis that says reductionist explanations of behavior are not possible and a hypothesis that says they are possible in principle (but not in practice with current limited computing power) would lead to the same consequence that we need distinct ways of understanding human behavior in everyday life, so that fact can't be taken to prove one hypothesis over the other.

@MoziburUllah "No, its not possible to derive peoples behaviour and that of life from physics. This is another myth from the physicalists stall." That's just an assertion, not an argument. Note that I didn't assert it was definitely possible, I just said "in light of the assumption that all behavior is in principle derivable from physics, this can be viewed as a useful approximate model".

@MoziburUllah "Still, I note that nothing in your quotes bu Democritus mentions mathematics as the only way to understand the universe" I only provided one quote by Democritus, and others by contemporary philosophers who would have had access to writings by him that are now lost, like Aristotle. Aristotle literally said that the atomists "make everything into numbers or composed of numbers", do you dismiss that?

@MoziburUllah "After all, he made fun of mathematicians who thought using the Banach-Tarski paradox to describe matter as a good idea" He was making the point that the construction has no physical meaning in current theories, if someone proposed a new mathematical theory of physics in which it did have physical consequences, his attitude expressed in "The Character of Physical Law" makes clear he wouldn't dismiss it based on "physical intuitions" prior to experimental testing.

@MoziburUllah "You are relying on Feynman as an authority" I already explained that I was relying on him for his experience of what approaches have been more or less successful in developing new theories in the 20th century, as well as to counter your specific claim that physicists rely on some non-mathematical notion of "causality" in their thinking.