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dawnofdusk

Re:Functions Are Asymmetric on Thursday October 16, 2025 @05:28PM (#45610894)
>Mathematicians are prone to taking words from elsewhere, either twisting their meaning or inventing wholly new meaning out of thin air, all according to their whimsy for their own particular needs.

True but one benefit of those guys is that they actually define what they mean in a formal way. "Programmers" generally don't. There is in fact some benefit in having consistent names for things, or if not at least a culture in which concepts have unambiguous definitions which are mandated.

>what this routing mechanism is (heating a substrate, maybe?)

You can engineer a waveguide if you understand the nonlinear theory they propose. There's no heat exchange involved, which is easy to get confused on because the writing in the article does not really understand "optical thermodynamics".

>if the routing is dynamically changeable

At this point probably not, it requires a finely engineered waveguide which has a well-defined "ground state"

>it works in reverse, eg light coming in can be routed to one of several output ports

In theory it works in reverse, as everything in this system is time-reversible (i.e., the "optical thermodynamics" is just an analogy and not real thermodynamics, which would break time reversibility). This is demonstrated via a simulation in the SI, but experimentally they did not achieve this (it may be difficult, I am not an experimentalist so cannot comment).

Re:An Illustrated Introduction to Linear Algebra on Tuesday October 07, 2025 @02:29PM (#45506883)
I really like the second part of the blogpost but starting with Gaussian elimination is a little "mysterious" for lack of a better word. It seems more logical to start with a problem ("how to solve linear equations?" "how to find intersections of lines?"), show its solution graphically, and then present the computational method or algorithm that provides this solution. Doing it backwards is a little like teaching the chain rule in calculus before drawing the geometric pictures of how derivatives are like slopes.
Re:An Illustrated Introduction to Linear Algebra on Tuesday October 07, 2025 @02:25PM (#45506830)
>My goal is to develop a practical, working understanding I can apply directly.

Apply directly... to what? IMO it is weird to learn theory (like linear algebra) expressly for practical reasons: surely one could just pick up a book on those practical applications and learn the theory along the way? And if in this process, you end up really needing the theory then certainly there is no substitute for learning the theory no matter how dense it is.

For example, linear algebra is very important to learning quantum mechanics. But if someone wanted to learn linear algebra for this reason they should read quantum mechanics textbooks, not linear algebra textbooks.

Re:A Thermometer for Measuring Quantumness on Friday October 03, 2025 @12:43PM (#45464918)
Although I am not an expert in quantum information, I think the problem you pose is resolved by the fact that the no-signalling theorem is about measurements of a quantum state, which is a microscopic state, and heat transfer is a measurement of a thermodynamic quantity, which is macroscopic. In much the same way that measuring the temperature of a classical gas doesn't give information on the location or momenta of the constituent particles, a thermodynamic probe of entanglement doesn't necessarily furnish precise information on how a state is entangled (e.g., Eq. 2 in https://arxiv.org/pdf/quant-ph/0406040).
I have some minor complaints but overall I think this is great! My background is in physics, and I remember finally understanding every equation on the formula sheet given to us for exams... that really felt like I finally understood a lot of physics. There's great value in being comprehensive so that a learner can choose themselves to dive deeper, and for those with more experience to check their own knowledge.

Having said that, let me raise some objections:

1. Omitting the multi-layer perceptron is a major oversight. We have backpropagation here, but not forward propagation, so to speak.

2. Omitting kernel machines is a moderate oversight. I know they're not "hot" anymore but they are very mathematically important to the field.

3. The equation for forward diffusion is really boring... it's not that important that you can take structured data and add noise incrementally until it's all noise. What's important is that in some sense you can (conditionally) reverse it. In other words, you should put the reverse diffusion equation which of course is considerably more sophisticated.

If it is factually wrong please tell me how.
The error in the OP is a typo that could never seriously confuse anyone, as the element Gr does not exist.

An interesting perspective is Terry Tao's on local vs. global errors (https://terrytao.wordpress.com/advice-on-writing-papers/on-l...). A typo like this, even if propagated, is a local error which at worst makes it very annoying to Ctrl-F papers or do literature review. Local errors deserve to be corrected, but in practice their importance to science as a field is small.

As any practicing scientist knows even good research papers may be littered with blatant but unimportant errors. There is unfortunately no good reason or system to "correct the record", and it is not clear to me if such a thing is a good use of human resources. Nonetheless, I think correcting the record is always appreciated!
Re:A visual introduction to big O notation on Monday August 25, 2025 @05:48PM (#45019459)
From what I read in the comments of the first post, the Pyon guy seems very toxic and pedantic, but the rebuttal by Ned isn't great. For example, nowhere in the rebuttal is the pedantic technical detail ever actually described. In fact the prose reads very awkwardly in order to circumlocute around describing it, just repeatedly naming it "particular detail". In my view, the author overreaches: he dismisses Pyon not only for the delivery of his criticism (which was toxic) but also the content of his criticism (why?).

Ultimately Ned is in the right about empathy and communication online. But as an educator it would have been nice to hear, even briefly, why he thought Pyon's point was unnecessarily technical and pedantic? Instead he just says "I've worked for decades and didn't know it". No one is too experienced to learn.

EDIT: I just skimmed the original comment section between Pyon and Ned and it seems that Ned is rather diplomatic and intellectually engages with Pyon's critique. Why is this level of analysis completely missing from the follow-up blogpost? I admit to not grasping the technical details or importance, personally, it would be nice to hear a summarized analysis...

Re:A visual introduction to big O notation on Monday August 25, 2025 @03:43PM (#45018105)
>This seems to be quite a bit of a strawman to me.

Not really, if you ever listen to CS undergrads or people in non-traditional schooling (bootcamps, etc.) talk about software engineering this opinion is essentially ubiquitous. People interested in ML are less likely to hold this exact opinion, but they will hold qualitatively identical ones ("do you really need multivariable calculus/linear algebra to do ML?"). It is precisely because people (primarily Americans) are scared to learn mathematics that they rationalize away this fear by saying the necessary mathematics must not be essential, and indeed it is true that many people get away without knowing it.

Re:A visual introduction to big O notation on Monday August 25, 2025 @03:39PM (#45018062)
It's reasonable but essentially every "common misconceptions about Big O" is because people didn't have the necessary notions in calculus. For example, the fact that O(x^2) can be practically faster than O(x), due to the size of constants/subdominant terms, is confusing only if you never properly learned what asymptotic behavior is.

The practical question is whether you think it's ok to continue propagating a rather crude and misunderstanding-prone idea about Big O. My stance is that we shouldn't: engineers are not business people or clients, they should understand what's happening not rely on misleading cartoon pictures of what's happening. I do not think you need a full-year collegiate course in calculus to get this understanding, but certainly you cannot get it if you fully obscure the calculus behind the idea (like this and uncountable numbers of blogpost explainers do).

Re:A visual introduction to big O notation on Monday August 25, 2025 @02:41PM (#45017382)
Whenever I read content like this about Big O notation I can't help but think the real solution is that computer science education should take calculus more seriously, and students/learners should not dismiss calculus as "useless" in favor of discrete math or other things that are more obviously CS related. For example, the word "asymptotic" is not used at all in this blog post. I have always thought that education, as opposed to mere communication, is not about avoiding jargon but explaining it.
Re:The contrarian physics podcast subculture on Thursday August 21, 2025 @05:52PM (#44978528)
Agree. Science communicators should stick to talking about well-established or at least peer reviewed results. They do not need to be peddling fringe crackpottery. I don't think Tim's prose is magnificent, but the work speaks for itself: he wrote a serious technical document which stands alone with no response. Serious, credentialed physicists should platform these types and not grifters.
Re:Is chain-of-thought AI reasoning a mirage? on Thursday August 14, 2025 @03:51PM (#44904843)
>but we know that reasoning is an emergent capability!

This is like saying in the 70s that we know only the US is capable of sending a man to the moon. Just because the reasoning developed in a particular context means very little about what the bare minimum requirements for that reasoning are.

Overall I am not a fan of this blogpost. It's telling how long the author gets hung up on a paper making "broad philosophical claims about reasoning", based on what reads to me as fairly typical scientific writing style. It's also telling how highly cherry-picked the quotes they criticize from the paper are. Here is some fuller context:

>An expanding body of analyses reveals that LLMs tend to rely on surface-level semantics and cluesrather than logical procedures (Chen et al., 2025b; Kambhampati, 2024; Lanham et al., 2023; Stechly et al., 2024). LLMs construct superficial chains of logic based on learned token associations, often failing on tasks that deviate from commonsense heuristics or familiar templates (Tang et al., 2023). In the reasoning process, performance degrades sharply when irrelevant clauses are introduced, which indicates that models cannot grasp the underlying logic (Mirzadeh et al., 2024)

>Minor and semantically irrelevant perturbations such as distractor phrases or altered symbolic forms can cause significant performance drops in state-of-the-art models (Mirzadeh et al., 2024; Tang et al., 2023). Models often incorporate such irrelevant details into their reasoning, revealing a lack of sensitivity to salient information. Other studies show that models prioritize the surface form of reasoning over logical soundness; in some cases, longer but flawed reasoning paths yield better final answers than shorter, correct ones (Bentham et al., 2024). Similarly, performance does not scale with problem complexity as expected—models may overthink easy problems and give up on harder ones (Shojaee et al., 2025). Another critical concern is the faithfulness of the reasoning process. Intervention-based studies reveal that final answers often remain unchanged even when intermediate steps are falsified or omitted (Lanham et al., 2023), a phenomenon dubbed the illusion of transparency (Bentham et al., 2024; Chen et al., 2025b).

You don't need to be a philosopher to realize that these problems seem quite distinct from the problems with human reasoning. For example, "final answers remain unchanged even when intermediate steps are falsified or omitted"... can humans do this?

It's not that troubling because we should not think that human psychology is inherently optimized (on the individual-level, on a population-/ecological-level is another story). LLM behavior is optimized, so it's not unreasonable that it lies on a Pareto front, which means improving in one area necessarily means underperforming in another.
Optimizing for one objective results in a tradeoff for another objective, if the system is already quite trained (i.e., poised near a local minimum). This is not really surprising, the opposite would be much more so (i.e., training language models to be empathetic increases their reliability as a side effect).
Basically the same as decrying why we should have to learn foreign languages instead of everyone speaking Esperanto.
Re:Ultrathin business card runs a fluid simulation on Friday August 08, 2025 @12:34PM (#44838955)
Essentially all physics simulations are either particle based or based on integration of differential equations (although in a computer both approaches involve a discretization which makes them somewhat computationally similar). You can consider reading through Numerical Recipes which is sort of the bible for this stuff for physicists, but it is aimed at scientific audiences with weak CS background. Something like Computer Simulation of Liquids by Allen could be a good start too. Let's be clear that the approach I'm talking about here is focused more on physical correctness: if you are a game designer it's not important that your fluid simulations are physically correct and more that it looks physically correct to a player, and there are a variety of more heuristic techniques for something like that.
Re:Hopfield Networks Is All You Need (2020) on Thursday August 07, 2025 @05:06PM (#44830356)
Yann LeCun (Meta AI head) is still all-in on energy based models, which are basically Hopfield-like. Not sure if there are any major developments in that direction, but the hype/optimism is still there. https://iopscience.iop.org/article/10.1088/1742-5468/ad292b/...
Re:Historical Tech Tree on Thursday August 07, 2025 @04:29PM (#44829932)
Pretty cool. Makes me think if we're overdue for another 1960s era tech boom?
Re:Why MIT switched from Scheme to Python (2009) on Friday July 25, 2025 @09:21PM (#44690458)
>FWIW our CS program mandated a programming languages class and the first third of the class was taught in Scheme.

This is important but doesn't replace having a dual-track intro sequence. The reason one has "physics for physics majors" isn't because physics majors need to learn some of this complicated stuff ASAP. They definitely don't, and I don't doubt students in the program will eventually get a well-rounded education. But it's a good idea to give incoming students a taste of what the field is like as soon as possible, so they can see if they like it or not. (Essentially it's a "weeder", but for the students' sake so they can self-select on interest and not just instructional staff's sake of being elitist.) Probably some (but not all) professors/postdocs/grad students would scramble to teach the more advanced sequence as it is likely more engaging for them than the current intro curriculum.

To be clear I don't think an advanced intro CS can't be in Python on principle, but such a class probably introduces multiple languages to some degree: they could be toy assembly languages or real ones in addition to the majority of the course content in Python.

Re:Why MIT switched from Scheme to Python (2009) on Friday July 25, 2025 @02:36PM (#44686642)
I think the solution is to have, as is the case in math/physics, an honors intro CS sequence compared to the regular intro CS class. The latter would be the recommendation for all non-CS majors, and the former would be for CS majors. I've always thought that those who are focusing on more vocational training should not be in what is called the CS program, maybe there are other majors called "software development" or "data science" or the like. Undeniably most prospective CS students are not aiming to go into academia, but we shouldn't adapt to this majority and then leave behind those who do want to do more academic things.

My background is in physics, where this sort of dual-track curriculum is well-established, and the physics taught to physics majors is very different from that taught to engineers. Unfortunately the difference is often boiled down to rigor or difficulty (and this will be reinforced if it's physics professors that have to teach both of the tracks), but in reality it is a value-neutral split which is based on pragmatism. CS should have one too.

Re:How to increase your surface area for luck on Wednesday July 23, 2025 @07:03PM (#44664959)
Another take along similar lines can be found in the book The Drunkard's Walk: How Randomness Rules Our Lives, by Leonard Mlodinow. Highly recommend.
Re:Trying Guix: A Nixer's Impressions on Friday July 18, 2025 @04:54PM (#44609726)
I mean they get evaluated in a weird way: for example you cannot use the `rec` keyword when declaring inputs.
I think the more interesting observation here, although the OP doesn't originally point it out, is that the spread of technology is associated with some sort of utility. Fashion and language seem more subjective: there's not a reason to prefer one over another. But with technology the idea is often that there are better or more productive tools. For example, the steam engine is more productive than the water wheel.

The point of "hype", on the other hand, and the reason to be "hype-optimistic" as the OP is, is that it can result in the spread of technologies that are not necessarily better. In other words, tech hype or marketing will not necessarily spread technologies in a meritocratic way. But actually what many cultural anthropologists know, such as by studying the spread of early human tools, is that there is a wisdom of the crowd effect where large social adoption of suboptimal technology tends to improve that technology unintentionally.

Those who decry "hype" are operating from an engineering background, where good tools are designed from the top down. But "hype" is more like a social force, which can emergently produce better tools from the bottom-up. The latter dynamic is robust yet uncontrollable, but it's definitely a real thing.

Re: on Tuesday July 15, 2025 @02:59PM (#44574644)
At this point I use AI primarily to write docstrings and to do annoying refactors. The value add in other situations is decent but not great, and IMO most of the agentic things are trying to iterate and implement way too much at one time. I prefer aider for this reason because it does very little.
Re:Perplexity Launches Comet for Pro Subscribers on Thursday July 10, 2025 @02:38PM (#44524122)
Is Apple supposed to be one of the kind and benevolent megacorporations?
Re:Perplexity Launches Comet for Pro Subscribers on Thursday July 10, 2025 @02:37PM (#44524113)
Not sure if it's the perfect example. Pretty sure Arc was shady before it had any AI stuff.
Re:Mercury: Ultra-Fast Language Models Based on Diffusion on Tuesday July 08, 2025 @01:41AM (#44497405)
Actually in most deep learning schemes for science adding in the "laws of nature" as constraints makes things much worse. For example, all the best weather prediction models utilize basically zero fluid dynamics. Even though a) global weather can be in principle predicted by using the Navier-Stokes equations and b) deep learning models can be used to approximately evaluate the Navier-Stokes equations, we now know that incorporating physics into these models is mostly a mistake.

The intuitive reason might be that unconstrained optimization is easier than constrained optimization, particularly in high dimensions, but no one really knows the real reason. It may be that we are not yet at the end of the "bigger is better" regime, and at the true frontier we must add the laws of natures to eke out the last remaining bits of performance possible.

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