I finished re-reading Anathem last month. Unfortunately, AFAICT, the tiling problem depicted in the book is fictional. Though I keep wondering if it is possible to make a real puzzle conform to the (somewhat vaguely) specified problem in the book.
503 karma · joined October 13, 2020
I didn't realize that Start.ca was sold this year. TIL
One could argue that this is just a kind of trick so they can say the next "binary" is actually a "source" file because it happens to be written by a human in ASCII.
Still the phase distinction between what is a source and what is a binary becomes blurry at this low level. I believe the next stage of compiling is to, writing in ASCII represented machine code with comments, to allow for the existence of labels and then compute offsets for jumps to labels. And then more and more features are added until you have a minimal assembler letting you write somewhat machine independent code, and then continuing to work you way up the toolchain.
So at which point does the translation from "source" to "binary" become a real thing and not just a trick of semantics? Is it when we have a machine independent assembly code? Is it when we computed offsets for labelled jumps? It is when we started stripping comments out of the source code?
Still, that POSIX operating system bit is also being worked on.
[0]Requirement: Provide at least two 20-amp, 120-volt circuits to supply power to GFCI (Ground Fault Circuit Interrupter) electric receptacles for countertop and eating areas. -- https://www.thespruce.com/kitchen-electrical-code-basics-182...
I suppose every time one makes an account one can register the two on-site keys, and then rotate one of your on-site key to off-site and take the off-site key home with you, and then finally register it.
Maybe I should get a third key...
That said, it is clear to me that the fuel economy one will get with the Prius Prime will depend heavily on the relative frequency of the various trips one takes.
-- Russell and Norvig, Artificial Intelligence: A Modern Approach, 4th US ed.
Removing schemes like cap and trade or Pigouvian carbon taxes because money is involved is a great way to end up doing nothing about carbon emissions.
Then we bought some more to give to everyone for christmas because we liked ours so much.
Lot of other good answers in this thread: split keyboard, trackball, iron skillet, etc. These items also spark joy for me. And I should probably stop thinking about getting a bidet and actually get one.
Tarsnap does full deduplication across all backups for any given "machine", while still letting you independently remove any snapshots you like. i.e. no special "full snapshot" that must always be kept around, and no need for multiple full snapshots that have no deduplication between them.
My main machine is currently storing 1.6 TB (compressed) of total archives with tarsnap, but only 33 GB (compressed) of unique data within those archives. So if S3 is 50x cheaper, then not having deduplication would be a wash.
However other comments here suggest that S3 is only 10x cheaper.
With regards to duplicity, Tarsnap does full deduplication across all backups for any given "machine", while still letting you independently remove any snapshots you like. i.e. no special "full snapshot" that must always be kept around, and no need for multiple full snapshots that have no deduplication between them.
I've been musing on this subject all afternoon. I'm a user of Tarsnap, and I do find it expensive, in the sense that I would prefer to backup larger amounts of data for less amount of money. At the moment I backup photos separately from Tarsnap and in an adhoc way.
But I still cannot figure out a way to get all the benefits I get from Tarsnap from any other software solution.
* Must be usable under Nixos.
* Backups must be asymmetrically encrypted so that backups can be automated, yet a compromise of the system cannot immediately gain read authorization to arcived data.
* Backups must be append-only without further credentials, or otherwise prevent a compromised system from being able to delete existing archives.
* Deduplication between archives while still allowing archives to independently be deleted.
Using the ZFS snapshot functionality with rsync.net, for example, with Duplicity comes close. However, as I recall, duplicity wants to regular (typically monthly) full backups and then incremental backups from there. You cannot remove these full backups without deleting the entire month's worth of backups, and because the full backups are independently encrypted, there is (of course) no deduplication between full snapshots, even though the data is still likely largely the same. And because the snapshots are encrypted, it is impossible for the rsync.net storage to see or even know that large parts of the encrypted data is identical.
AFAICT there is really nothing else that does what Tarsnap does.
I just now need a deduplicating asymmetrically encrypted backup program.
I've tried duplicity in the past, and maybe I should try it again. But my recollection is that duplicity will just fail to do backups at the slightest hint of any problem. Like maybe if the last backup was interrupted then no more backups for you until you attend to it.
Edit: More memories returning of having to dig out my decryption key to resync the metadata when duplicity gets unhappy, and then since my target server was append-only, duplicity was upset when it wasn't allowed overwrite any of it's incomplete metadata files. I guess the ZFS snapshot technique would alleviate the latter issue.
To be fair, if tarsnap gets confused it needs the keys to do its fsck command, but I recall this sort of thing happening regularly with duplicity and almost never with tarsnap.
The thing is that tarsnap deduplicates over arbitrarily long time periods, letting me make arbitrarily long staggered sequences of retained archives.
Perhaps I should really reconsider if I really need such long lived archives, but it is hard to bring myself to drop them.
This ability is critical to prevent a compromised system from having its data wiped and having all backups wiped as well.
I haven't been able to figure out how to do this in any other system. But if someone has a tutorial, I am all ears.
But my act of calling out a word isn't just mental, it is physical. It causes physical vibrations in the air, and choosing different words causes different physical vibrations. And according to physics we can trace back the events leading up to the vibration in the air, which are caused by vibrations in my larynx and the shape of my mouth, each pulled in turn by contractions of muscle fibres that are happen when they are bathed in acetylcholine released by neurons attached to those fibers. The neurons are in turn linked together by electrical and chemical connections, all in turn following the laws of electrical and chemical potentials though their interactions with each other, each in turn following the laws of physics.
If I had a free choice, then somewhere that free choice interacts with the physical environment. If the same situation were somehow to truly arise again, as in the state of my brain is the same, the wind touching my skin is identical, the radiation falling from the sun on my face is identical, and I have a free choice, then the evolution of the state of me and the entire worlds diverges at some point, the point at which I make a free choice.
Quantum mechanics does allow divergence similar to this. In the observation of measurements in quantum mechanics, quantum theory says that identically prepared experiments can yield different results in which the probability of each result following the Born rule. However these results are random, and not based on a free choice. If we try to use measurement as a way to cause the state of the world to diverge based on my free choice, then I could be using my free choice to violate the Born rule, which could then in turn let me freely violate the conservation of energy and conservation of momentum, etc.
I acknowledge that our understanding of quantum physics isn't complete. The so-called vacuum catastrophe remains unexplained as just one example. And what the heck is qualia anyways? So it may be possible that a later theory does, somehow, give an opening for free will.
But just as the theory of the earth being flat was refined to be a sphere and then later refined into an oblate spheroid, each refinement of physics theories cannot stray too far from the previous one, as all the previous experimental results have to be maintained. Thus any updated version of quantum physics will need to maintain something close to unitary evolution of quantum states and it will need something close to the Born rule to make quantum events that appear to follow a random distribution, and will want to at least nearly respect conservation of energy and momentum.
Thus I remain skeptical of any refinement of physics ever enabling free will. But yeah, maybe it isn't entirely impossible.
After reading his comment, I had the thought and an urge to type up a response to attempt to clarify that I indeed understand the idea that thoughts not under my control and my lack of free will are somewhat independent aspects (it is certainly possible to imagine both having free will at some subconscious level and also seeming to have no direct control over one's thoughts that appear in consciousness), and add that my primary reason for doubting free will is physics based.
No serious counter-thoughts or other considerations appeared, i.e. it didn't seem dangerous or harmful to reply. So I ended up succumbing to my urge type up a reply and in fact did so.
TL;DR: I couldn't help myself.
Free will or not, I don't see how I can change my belief system in such a way to exclude the possibility that I'm a brain in a vat, so in that sense I don't see how I can ever 100% believe my experiences match reality short of attempting to tautologically define my experiences as what reality is.
Since you claim have free will, I'd be interested in how you experience the sensation of freely choosing a movie or song title and where exactly your free will comes into play within those sensations, and of how your sensations of the task differ from mine.
That my thoughts are not under my control is the counter argument to the claim "But then how is it that you feel like you do have free will?" The answer to this is that, upon more careful introspection, it seems I don't even really feel like I have free will either.
Like, maybe the world is inhabited by leprechaun's holding up cardboard facades of the city when I'm walking through it always hiding themselves. Or maybe my brain is in vat, hooked up to a computer that is making me believe that I'm experiencing typing out this comment. Or maybe I have no brain at all and I'm just an improbably quantum fluctuation in unfathomably large dead universe that just for a fraction of a second creates an experience of typing on a keyboard and the sensation of having a history that never was, a Boltzmann brain.
I accept that all the above are possible, but I don't "believe in them". I do believe in determinism (plus randomness) with about the same conviction that I believe the keyboard that I am tapping on exists.
> It also fails to account for our mental lives, given the experience we all have.
So this is what got me quite recently.
I remember a while back Henk Barendregt remarked something to the effect that everything that happens either follows deterministically from past event or happens randomly, and in neither case is there any free will.
I remember accepting that from what I know of physics this does seem to be the case. I'm not aware of any violations of the Borne rule that would allow for any event to be neither random nor deterministic. But, that the time, I remember thinking that it did seem strange that I feel like I have free will.
But recently, I've been listening to Sam Harris's Waking Up app, and, in addition to meditation practices, he has a section where he argues, convincingly in my opinion, that if you pay attention, there isn't actually any feeling of free will either.
For instance, if I am sitting and meditating and I am trying to pay attention to my breathing, or trying to pay attention the the bird chirping outside my window, then often, usually only after a few seconds, I suddenly find myself thinking about what I'm going to make for dinner, or remembering that time I was talking with my aunt about her birdwatching hobby, or any number of a million possible intrusive thoughts.
I certainly do not freely will these thoughts into existence. My will is supposedly to be paying attention to what I am hearing, or the experience of breathing. Yet inevitability I eventually end up distracted by whatever pops into my head at any given moment.
And after spending some time paying attention to my experience, I cannot help but see that Harris is right. He suggests taking the example of picking a movie, any movie. Just pick one and pay attention to the experience of freely choosing a movie title. For me, just now, I picked "Ghostbusters". But it was simply the first title that popped into my head.
Is this free will? The title popped into my head the same way that thoughts intrude into my meditation, just appearing in consciousness with no source in sight. No particular explanation as to why one title appears and not another.
Try again and think up three songs and choose one of them. Take as much time as you want. Make this choice as freely as you like. But also watch as the titles just appear in your consciousness from nowhere to be seen. Watch as you /deliberate/ about which one to pick. Reasons, like all thoughts, just start popping into one's head from nowhere to be seen. "I really enjoy X song" or "X song is quite popular" or "I haven't listened to X in a while, maybe I'll pick it then go listen to it". All these reasons for freely picking a title are just popping into consciousness in just the same way that the titles appeared in the first place. Maybe the thought pops into your head that you should just roll a die to choose one of the three.
Upon examination, my experience of deliberation is just the same as my experiences of other kinds of thoughts. I simply experience reasons popping into my head relating to the choice at hand, but I have no real control over which reasons will appear. They all just start to show up. Maybe eventually a thought appears, "Ah, that is a good reason to do X". Did I just freely come to a choice? Am I in control of that thought? That last thought just popped into my head in the same way that every other thought did, and I don't recall choosing to come to a final conclusion.
Anyhow upon this recent introspection on my own mental life, it now feels completely compatible with the lack of free will. While it doesn't conclude that I for sure have no free will, it doesn't actually look like I have it. The thoughts that enter my consciousness don't directly appear to have any origin. They just appear in consciousness in a way not so different from the appearance of the sound of a bird chirping outside my window does. I don't have any direct control over what thoughts will appear in my consciousness. And what type of thoughts that do appear in my head seem to be at least somewhat influenced from past experiences. i.e. they do kinda look like something that is offered up based on some combination of determinism and randomness.
Minor correction. Goedel's theorem applies to decidable (a.k.a. computable) sets of axioms. e.g. Peano's axiom, when written in first order logic, contain an infinite set of induction axioms that follow a specific and recognizable (i.e. decidable) pattern.
In fact, Goedel's theorem applies even beyond that including any set of axioms whose syntax can be specified by some (first order) mathematical predicate, even if that predicate is not computable in any way.
> Meaning there could be another set of axioms under which the limitation to prove that such a statement is true disappears. But it doesn't make math any less true.
Indeed, when studying logic it is common to consider the set of all true first-order (arithmetic) statements, which necessarily forms a complete and consistent set of axioms. Of course, given Godel's incompleteness theorem it must be the case that such a set of axioms isn't computable. Not only that, but it cannot be even defined in a first-order (arithmetic) way, which leads the the corollary of Tarski's undefinability theorem[0].
[0] https://en.wikipedia.org/wiki/Tarski%27s_undefinability_theo...
P.S. There is no free will and one's thoughts are indeed out of one's control. I'm not certain that implies one should never trust one's thoughts. Though it does make sense to take them with a grain of salt. See for example, "The past is not true" (https://news.ycombinator.com/item?id=36798854).
P.P.S I'm not saying your argument is invalid. It can both be the case that materialism is contradictory and there is no free will.
As for email clients, just use whatever Netscape comes with.
"But there is a way of turning this logic around. We can begin to do things not in spite of death, but because of it. More and more, we can lean into the truth of impermanence. And rather than make us morbid, it can make us appreciate just how beautiful life is. You're alive! What do you get to do today? You can go for a walk. You can make pancakes for someone you love. You can read a good book.
"When you do these things, in spite of death, everything can seem ultimately pointless. But when you truly embrace impermanence, the point is always now. You get to make full contact with the reality of life... now! What other point or purpose could you hope for?
— Sam Harris (Waking up App)
---
In the Summer of 1951, Professor G. Uhlenbeck gave his
famous course on Statistical Mechanics at Stanford, and fol-
lowing the lectures I had many conversations with him, over
lunch, about the foundations of the theory and current progress
on it. I had expected, naively, that he would be enthusiastic
about Shannon's work, and as eager as I to exploit these ideas
for Statistical Mechanics. Instead, he seemed to think that
the basic problems were, in principle, solved by the then
recent work of Bogoliubov and van Hove (which seemed to me
filling in details, but not touching at all on the real basic
problems)--and adamantly rejected all suggestions that there
is any connection between entropy and information.
His initial reaction to my remarks was exactly like my
initial reaction to Shannon's: "Whose information?" His
position, which I never succeeded in shaking one iota, was:
"Entropy cannot be a measure of 'amount of ignorance,' because
different people have different amounts of ignorance; entropy
is a definite physical quantity that can be measured in the
laboratory with thermometers and calorimeters." Although the
answer to this was clear in my own mind, I was unable, at the
time, to convey that answer to him. In trying to explain a
new idea I was, like Maxwell, groping for words because the
way of thinking and habits of language then current had to be
broken before I could express a different way of thinking.
Today, it seems trivially easy to answer Professor Uhlen-
beck's objection as follows: "Certainly, different people
have different amounts of ignorance. The entropy of a thermo-
dynamic system is a measure of the degree of ignorance of a
person whose sole knowledge about its microstate consists of
the values of the macroscopic quantities Xi which define its
thermodynamic state. This is a completely 'objective' quantity
in the sense that it is a function only of the Xi, and does not
depend on anybody's personality. There is then no reason why
it cannot be measured in the laboratory."Entropy isn't a property of an object, or a system or things in physics. Entropy is a property of our _description_ of systems. More precisely it is a measure of how poorly a given specification of a physical system is, i.e. given description of a systems, typically the pressure / volume / temperature of a gas or whatnot, how many different physical systems correspond to such a description.
In particular, _thermodynamic entropy is Shannon entropy_.
In the case where the description of state specifies a volume of phase space wherein a physical state lies within, then the entropy is the logarithm of the volume of this fragment of phase space. If we take this collection of states and see how they evolve in time, then Liouville’s theorem says the volume of phase space will remain constant.
If we want to build a reliable machine, i.e. an engine, that can operate in any initial state that is bounded by our description, and ends up win a final state bounded by some other description, well, in order for this machine to preform reliably, the volume of the final description needs to be greater than the volume of the description of the initial state. Otherwise, some possible initial states will fail to end up in the desired final state. This is the essence of the second law of thermodynamics.
I want to emphasis this: entropy exists in our heads, not in the world.
E.T. Jaynes illustrated this "5. The Gas Mixing Scenario Revisited" in https://www.damtp.cam.ac.uk/user/tong/statphys/jaynes.pdf where two imaginary variants of Argon gas are mixed together. If one engineer is ignorant of the different variants of Argon gas, it is impossible to extract work from the gas, but armed with knowledge of the difference (which must be exploitable otherwise they wouldn't actually be different) work can be extracted.
Knowledge _is_ power.
Taking an extreme example, suppose we have two volumes of gas at different volumes / pressures / temperature. We can compute how much work can be extracted from those gases.
But, suppose someone else knows more than just the volume / pressure / temperature of these gases. This someone happens to know the precise position and velocity of every single molecule of gas (more practically they know the quantum state of the system). This someone now gets to play a the role of Maxwell's demon and separate all the high velocity and low velocity molecules of each chamber, opening and closing a gate using their perfect knowledge of where each particle is at each moment in time. From this they can now extract far more work than the ignorant person.
In both cases the gas was identical. How much useful work one can extract depends on how precise one's knowledge of the state of that gas is.