x86 has (not counting the system-management mode stuff) 4 major modes: real mode, protected mode, virtual 8086 mode, and IA-32e mode. Protected mode and IA-32e mode rely on the bits within the code segment's descriptor to figure out whether or not it is 16-bit, 32-bit, or 64-bit. (For extra fun, you can also have "wrong-size" stack segments, e.g., 32-bit code + 16-bit stack segment!)
16-bit and 32-bit code segments work almost exactly in IA-32e mode (what Intel calls "compatibility mode") as they do in protected mode; I think the only real difference is that the task management stuff doesn't work in IA-32e mode (and consequently features that rely on task management--e.g., virtual-8086 mode--don't work either). It's worth pointing out that if you're running a 64-bit kernel, then all of your 32-bit applications are running in IA-32e mode and not in protected mode. This also means that it's possible to have a 32-bit application that runs 64-bit code!
But I can run the BCD instructions, the crazy segment stuff, etc. all within a 16-bit or 32-bit code segment of a 64-bit executable. I have the programs to prove it.
> The problem with extremely smart people is not many people understand them.
I know this is a common trope in many media portrayals, but it's really not my experience. The "insufferable genius" stereotype tracks most not for the extremely smart people but the kinda-smart people who are absolute jerks but try to defend their jerkassery on the basis of their intelligence.
The few very brilliant people I've known devoted themselves to master a subject, at the cost of neglecting others, like socialization. They were not autists by any measure of the condition, just very socially undeveloped. Some embraced the awkwardness, but others chose to be jerks because it is easier than rescuing an atrophied skill. The jock equivalent of wearing baggy pants because they skipped leg days.
I've also known a handful of artists, and some seemed to adopt the tortured artist stereotype out of style, not fate. They were convinced no one would take them seriously artistically if they weren't interesting and eccentric. In their case, being a jerk is a fashion.
I guess my point is, we choose what skills we want to develop, and also if we accept the skill exchange, or make excuses like "I'm bad at X", "I am this way and can't change", etc. Leave that to people that are actually diagnosed with a limiting condition; they usually put a great deal of effort and still need help to succeed.
I understand where you're coming from. I wasn't meaning from the context of the pseudo-smart person portraying that (which is obviously a thing, probably more obvious nowadays), but a person that is the real article. You meet all walks of life in your lifetime and that unattainable-ness of very smart people can come across as inaccessible, unexplainable or arrogant.
The kind of person that has spent much time chiselling their belief system or is simply fascinated by a field of study that not many people can relate to on that depth. Feynman was a great communicator, but I can think of a few people that may have Asperger's syndrome that have that exceptional insight into things that sometimes results in collateral damage in relationships.
What I mean is there are exceptional people, and sometimes people fail to understand what is exceptional and take exception themselves.
The political narrative of the time obviously was extra cynical about declarations of which team you're playing for, or non-declaration. That's what I meant about non-conformist, they're not interested in the politics.
> The "insufferable genius" stereotype tracks most not for the extremely smart people but the kinda-smart people who are absolute jerks but try to defend their jerkassery on the basis of their intelligence.
Autism plays a lot into this. You'll get people who can seem condescending or unaware of different social norms, and it's genuinely not from a bad place, just a complete inability to understand their own communication style (especially in the moment).
> Autism plays a lot into this. You'll get people who can seem condescending or unaware of different social norms
Recently "autism" is a scapegoat for everything, both claiming to be autist to get a free pass to be a jerk, or calling someone autist because they do something unexpected.
I have been called autist after a meeting just because I said something could not be done in the timeframe proposed. Acording to social norms, the correct thing to do was to lie, say it could be easily done, and deal with expected missed deadlines with even more lies.
Another "autism" trait I have is to say a dry "no" to invitations I don't want to attend, apparently the social norm is to say "yes" and then fake an excuse a couple of hours ahead, or even worse, just don't go.
The point is the word "autism" (or even jerk) is being used as a synonym of "direct", "sincere" or "no bullshit" too often. And I am not talking about calling people fat or ugly out of the blue (that's a real jerk), but saying "no" when it is enough.
> misogynistic behaviors were cultural at the time, I agree they're abhorrent but people are embedded in their culture.
Moral relativism is a thing, but I think a more useful way to think of it rather than just saying "misogyny was a thing back then, should we care he was a misogynist then?" is to ask "if he were to have lived and worked in the 2000s, would he associate with Epstein?" And to be honest… Feynman does strike me as the kind of person to have the intellect to attract Epstein's attention and also the, for lack of a better term, party attitude to go to a couple of Epstein's parties that would result in him having awkward press releases trying to explain that he just had no possible idea that Epstein was doing anything sexual with children and conveniently forgetting all the times he was on the private island for some party or another...
That's the real strong vibe I get from Surely You're Joking. He's the kind of person who wants to be seen as someone who gets up to wacky hijinks, to be seen as "cool," and he specifically interprets "cool" in a way that's misogynistic even at a time (when he was dictating the stories that led to Surely You're Joking) when misogyny was starting to become a professional hindrance.
(And one of the things that really worries me about Surely You're Joking is that it's often recommended as a sort of "look at the wacky hijinks you can get up to as a physicist," so recommending the book is a valorization of his wacky hijinks and... well, that's ultimately what Angela's video is about, that's a thing we need to stop doing.)
> That's the real strong vibe I get from Surely You're Joking. He's the kind of person who wants to be seen as someone who gets up to wacky hijinks, to be seen as "cool," and he specifically interprets "cool" in a way that's misogynistic even at a time (when he was dictating the stories that led to Surely You're Joking) when misogyny was starting to become a professional hindrance.
In my experience, everyone who says this is talking about exactly one chapter in Surely You're Joking, but they don't appear to actually have paid close attention to the story. It's a story that Feynman recounts about trying to pick up girls when he was younger. He was advised by an older, "cooler" man to be mean. Feynman tries it and it works, but he feels bad about it and says that he never did it again. People calling Feynman a misogynist for this story seem to have just skipped the end of the chapter.
It's been decades since I read Surely You're Joking, and I've completely forgotten about that chapter. It plays no part in my conscious recollection of the book.
The episode that really stuck in my mind was the episode about his competition with the abacus-user, who was better at math, which essentially ends with him giving up trying to explain how he could mental math a cube root faster, because the abacus-user was just someone who couldn't understand a math explanation.
I remembered enjoying the book, so having not read it in a long time, I tried sharing Surely You're Joking with my kids at bedtime.
That chapter wasn’t the only thing I ended up skipping or heavily editing.
* Picking a room at Los Alamos with a window facing the women’s housing, but being disappointed that a tree or something blocked his view. (Wasn’t he also married at this point?)
* Starting a new Uni faculty position and hanging out at student dances, dismayed that girls would stop chatting & dancing with him when they learned he was a prof and not a fellow student.
* Hanging out at strip clubs to practice his drawing skills.
* Considering a textbook sales rep’s offer to help him find “trouble” in Vegas.
So maybe that one chapter turns around some at the end, but it’s not the only cringe-worthy moment in the book, and I can see why some people may have an overall negative opinion.
If I were going to do this with my kids now that they are teens, I wouldn’t filter as much and use the more questionable events as points of discussion.
This is from Lawrence Krauss[0]'s email to Epstein[1]:
> ps. I have decided that Feynman would have done what I did... and I am therefore content.. no matter what... :)
> On Apr 6, 2011, at 3:56 PM, Jeffrey Epstein wrote:
> what evidence? no real sex.. where is she getting her so called facts
Krauss's letter is obviously horrible in its implications. What's interesting to me is his interpretation of what Feynman would have done. Is it his delusional justification of what he'd done with Epstein, or is it based on a certain reputation of Feynman in the science community?
> The fundamental laws of chemistry have not been changed much by quantum physics, they just became better understood and less mysterious. Quantum mechanics has explained various cases of unusual chemical bonds that appeared to contradict the simpler rules that were believed to be true before the development of quantum physics, but not much else has practical importance.
Um, false? The fundamentals of chemistry are about electron orbitals (especially the valence ones) and their interactions between atoms to form molecules. All of my college chemistry courses delved somewhat into quantum mechanics, with the biggest helping being in organic chemistry. And modern computational chemistry is basically modeling the QED as applied to atoms.
> If our unit of charge had been set when we knew about quarks, we would have chosen those as fundamental, and the charge of the electron would instead be -3.
Actually, I doubt it. Because of their color charge, quarks can never be found in an unbound state but instead in various kinds of hadrons. The ways that quarks combine cause all hadrons to end up with an integer charge, with the ⅔ and -⅓ charges on various quarks merely being ways to make them come out to resulting integer charges.
If I were targeting Rust for compilation, I wouldn't do lifetimes, instead everything would be unsafe Rust using raw pointers.
I'd have to do an actual project to see how annoying it is to lower semantics to unsafe Rust to know for sure, but my guess is you'd be slightly better off because you don't have to work around implicit conversions in C, the more gratuitous UBs in C, and I think I'd prefer the slightly more complete intrinsic support in Rust over C.
> Now, if a and b are already float, then it's equivalent.
Not necessarily! Floating-point contraction is allowable essentially within statements but not across them. By assigning the result of a * b into a value, you prohibit contraction from being able to contract with the addition into an FMA.
In practice, every compiler has fast-math flags which says stuff it and allows all of these optimizations to occur across statements and even across inline boundaries.
(Then there's also the issue of FLT_EVAL_METHOD, another area where what the standard says and what compilers actually do are fairly diametrically opposed.)
The first mention of contraction in the standard (I'm looking at N3220 draft that I have handy) is:
A floating expression may be contracted, that is, evaluated as though it were a single opera-
tion, thereby omitting rounding errors implied by the source code and the expression evalua-
tion method.86) The FP_CONTRACT pragma in <math.h> provides a way to disallow contracted
expressions. Otherwise, whether and how expressions are contracted is implementation-defined.
If you're making a language that generates C, it's probably a good idea to pin down which C compilers are supported, and control the options passed to them. Then you can more or less maintain the upper hand on issues like this.
The magic here with the word-ese is that a floating point expression may be contracted. In C, you write things like:
float a = /*expression*/
float b = /*expression*/
float c = a * b;
Contraction can only happen within the expressions on the right hand side, not mutually between a and b. This makes inlining, and even variable substitution not legally permitted by the C spec to be equivalent to the actually written out inlined version. Ie you can't transform:
float a = v1 * v2;
float b = v3 * v4;
float c = a + b;
Into
float c = (v1 * v2) + (v3 * v4);
As they aren't semantically equivalent, and compilers do follow these rules. The same applies for inline functions. Its one of the reasons why macros can sometimes perform better than force-inline functions
In practice, the big 3 compilers all perform floating point contraction according to the spec, and this is a major issue if you want to get good gpgpu performance because this extends to OpenCL and C-style languages in general (like CUDA)
If you allow contraction after inlining, whether or not an FMA will get contracted becomes subject to the vicissitudes of inlining and other compiler decisions that can be hard-to-predict. It turns out to be a lot harder of a problem to solve than it appears at first glance.
Chomsky is very well known for the fact that his anti-US imperialism stance is strong enough that he becomes a standard bearer for any malodorous regime the US is against, starting from his denial of the Cambodian genocide and attempted habilitation of the Pol Pot regime through to, most recently, his denial of any Russian atrocities in Bucha, Ukraine (his last major public commentary before his stroke).
It is entirely in line with Chomsky's historical pattern that Epstein could walk up to him, say "the US government hates me and claims I'm a pedophile" and for Chomsky to then treat him like his best friend. It is also worth noting that when he eventually recanted his Cambodian genocide denial, he basically said something along the lines of "how could anyone have possibly known just how bad the regime was?" which is... essentially what this response is attempting to be, "how could we have possibly known that Epstein was actually a pedophile?"
I always got the feeling Chomsky went for "the big picture" so to speak, and ignored the details. At least, that would be consistent between his political and his linguistic work. In the latter, he built systems that were simply too complex to be representative of the human mind. I can imagine that he saw himself as a kind of continuation of Marx and Hegel, where the system matters, and human life is just a detail.
16-bit and 32-bit code segments work almost exactly in IA-32e mode (what Intel calls "compatibility mode") as they do in protected mode; I think the only real difference is that the task management stuff doesn't work in IA-32e mode (and consequently features that rely on task management--e.g., virtual-8086 mode--don't work either). It's worth pointing out that if you're running a 64-bit kernel, then all of your 32-bit applications are running in IA-32e mode and not in protected mode. This also means that it's possible to have a 32-bit application that runs 64-bit code!
But I can run the BCD instructions, the crazy segment stuff, etc. all within a 16-bit or 32-bit code segment of a 64-bit executable. I have the programs to prove it.
reply