Browser Market Pollution: IE[x] is the new IE6 - <AUTHOR> http://paulirish.com/2011/browser-market-pollution-iex-is-the-new-ie6/ <comment><USER3> I saw this on paul's G+ and rolled my eyes.

Oh guffaw. The time has easily come where we are allowed to say "no" to several browser versions, or at least ignore them. Even Google has dropped support for IE6.

Supporting several browsers does not mean that a website has to look perfect in all those browsers. My sites will look good on the latest version of Chrome, IE, Opera, and Firefox.

Users of IE6/7/etc are already self-inflicting harm on their own web experience, why should we care to cater to them? They can have the website I display, but I'm not building the site for the past.

I don't care if previous browser users see the Best Of All Possible Websites, as long as they see something. And since I'm developing Canvas apps, I don't care if some of them see anything at all.

I imagine IE will reluctantly take the road of Chrome or FF and be more insistent about updates, especially outside of the corporate world. I also think that in the future the consensus will be that there isn't anything wrong with dropping support for aged browsers, and just displaying one "simple" site version to them.

<comment><USER4> I've never really understood the outward hostility Web developers display towards their clients, audience, customers, etc. Your job is to deliver the best experience you can for people viewing Web pages. If given all the information at your disposal, the costs don't outweigh the pros for your audience, that's one thing. But not doing it because it's hard or you just don't feel like it is a bit childish (please note I'm using "you" to mean the prototypical Web developer here -- not you as in simonsarris).

We all have to do things we don't like in our jobs, that's just part of it being a job. I can even accept a certain amount of healthy advocacy. Encourage people to upgrade if you'd like. But outright refusal to do your best because your customer doesn't run the browser you wish they did is just a very odd tactic to take.

<comment><USER5> In the real world time is limited and expensive resource, and the more of it you spend catering to a small fraction of users, the less you can spend on improving your service in other ways – possibly more beneficial to the end users.

It's a matter of trade-offs that have to be made based on intended audience and information available. No need to be offended.

<comment><USER4> Sure. Like I said, if you're actually measuring it, then that's one thing. But supporting older browsers usually isn't that hard if you know what you're doing. Obviously there are some features that you just can't backport and there's not much you can do there. But more often than not I read comments like "as a policy, I just won't support IE < 9."

In any event, the cost argument is the purview of the business owner perspective, not the Web developer. And it's hard to look at in isolation. I don't know that many sites that wouldn't love to have another 5% of traffic. Yeah, it may cost more to support older browsers, but driving traffic to a site costs money, whether through ads or spending time on inbound marketing. Trying to bump conversion rates on your existing traffic costs money and time as well.

There's obviously a balance to it. At the extreme end, I know of businesses that support anything with > 0.5% market share because at the volume they operate at, it's worth millions. At the other end, I see startups fight tooth- and-nail working on their funnels, while throwing away legitimate sources of revenue.

<comment><USER5> It's rarely all-or-nothing. For me "not supported" means that the site wasn't extensively tested on a given browser or it doesn't offer full experience, not that it doesn't work at all. Another issue is whether those enterprise IE6 users are really the target audience of your startup.

Anyway, it seems like we both agree that it should be a deliberate decision.

</comment></comment></comment></comment></comment><comment><USER6> > IE6 has been a source of pain for… I'd say four years.

We're in late 2011 right? That puts Paul's "IE6 being a pain" in late 2007, right after the original iPhone was released.

By that time, Firefox 2 was a year old, Firebug was 18 months old, and Safari 3 (the first version with acceptable Javascript support) had just been released, making Drosera (which would morph into the Webkit Developer Tools the next year) available.

Hell, by late 2007 _IE7 was a year old already_. And a significant reason why the IE project was restarted (and IE7 produced) is developers getting fed up with IE6, its bugs, its antiquated tools and its lack of progress, and Firefox had been getting more and more traction since its 1.0 release in late 2004.

IE6 has been a pain for at least 6 years now. 2005 was Firefox 1.5, the announce for the IE project restart and the grand opening of On Having Layout [0], the tail end of the long, slow and painful discovery of IE6's innumerable rendering bugs, DOM and javascript limitations (anybody else remembers Drip and Joel Webber's "DHTML leaks like a sieve"? That's January 2005), painfully slow runtime & al.

Of course it makes sense that 2005 would have been such a sticking point: the web community had been playing around with CSS since ~2003 (CSS Zen Garden released that year) and was wrapping up the IE6 CSS bugs compendium (see above-mentioned On Having Layout, pretty much the culmination of the effort).

Late 2004 and (especially) 2005 it started to turn its attention from styling to behavior, which lead to the rebirth of Javascript and the creation of modern javascript: AJAX coined (and seminal article on the subject published)? February 2005. Opera Desktop free and ad-free? April 2005 QuirksBlog? December 2004. The killing of "DHTML"? 2005[1]. <http://simonwillison.net/2005/Jan/5/swissMaps/> [http://www.mezzoblue.com/archives/2005/01/06/dhtml_05/index....](http://www.mezzoblue.com/archives/2005/01/06/dhtml_05/index.php), ... the javascript frameworks explosion was also 2004 (Dojo) through 2005 (Prototype, Mochikit) to 2006 (jQuery, YUI)

[0] <http://www.satzansatz.de/cssd/onhavinglayout.html>

[1] <http://adactio.com/journal/938>

<comment><USER7> Actually, by late 2003 Phoenix (which is what Firefox used to be called back then) was already an impressive little browser (it was little back then) and IE6 was already horribly outdated and clumsy for those of us who grew a penchant for alternative browsers (the others being Opera and the Mozilla Suite).

<comment><USER6> I completely agree, but developers-wise it was not a complete pain in the ass yet: it was the "looking forward to meeting you" browser for the development community (having just been renamed Firebird), the community was mostly in its IE5/Mac high and getting started on understanding CSS and trying to get rid of tables.

This would lead down a long and painful road re. IE6, but I think it was just getting started and not feeling it yet. On the Phoenix/Firebird/Firefox front, Chris Pederick's Web Developer Toolbar was still a year away.

(there were, of course, visionaries community wise: PPK published "Separating behavior and structure" in April 2004[0], and the "javascript prophets" were getting out their suggestions on getting event handler bindings out of HTML[1], it's a long gone time when Opera's javascript support was billed "poor" and the first version of Safari had little CSS support and no ability to execute any javascript worth running)

edit: after thinking about it a bit more, i still think 2003 is too early for the IE6 pain point, but my 2005 might be too conservative as well. So I'd put the early pangs in early to mid-2004 for the "wider" community of developers interested in web technologies.

[0] [http://www.digital- web.com/articles/separating_behavior_and_...](http://www.digital- web.com/articles/separating_behavior_and_structure_2/)

[1] <http://www.sitepoint.com/structural-markup-javascript/>

<comment><USER8> And BTW, the year 2003 was when MS said that future versions of IE would come only as part of OS upgrade/updates.

</comment></comment></comment></comment><comment><USER9> The 72 browser versions thing is an exaggeration. For _your_ websites, add this tag: <meta http-equiv="X-UA-Compatible" content="IE=edge" /> \- and you force IE to use that version's latest documents mode. So good point about IE's slow adoption, it really is annoying and holding back the web - but for _your_ websites, you can easily force the document mode of your choice, avoiding the crappy emulated modes.

<comment><USER10> Absolutely. That line is critical to avoiding pain. Library authors don't have that option, unfortunately. :/

But even if we ignore the compat versions for now (and quirks mode (and almost-quirks mode)), we still end up with up to 10 IEs in play simultaneously.

<comment><USER9> Good point about library authors... that's a headache!

</comment></comment></comment><comment><USER11> You kids these days don't know how good you have it. Back in the day, when applications ran on the computer instead of in the browser, we would have killed to have only 76 different configurations to support. (And I'm not joking, though I am smiling ruefully.)

<comment><USER12> Pshaw.

 _We_ had _one_ computer. And _one_ program that ran on it. And we _liked_ it that way.

(OK, but we had a gazillion VMs so we could all run our one program on our one computer, except that we could never schedule any CPU time).

</comment></comment><comment><USER13> > How many browsers would you like to support?

I don't support browsers. I support standards. I stopped performing hacky compatibility gymnastics long before Google made it cool to boast how you weren't supporting IE6 anymore, and my workflow and sanity has improved due to it.

<comment><USER13> To extend my point, I don't care if the user wants to use Firefox or Chrome or even IE. The rendering should be consistent across the board, and the browser should be about the user experience. Add ons, syncing, other such features.

Imagine if this applied to the world of televisions. If people didn't buy Sony TVs because they didn't display channels as well as Sharp or Panasonic. If you had to render your video with some hacky kludge so the colors displayed right on a Samsung and an LG. That would be insane.

<comment><USER14> Remember the "web-safe" 216-colour palette? :(

</comment></comment></comment><comment><USER15> This sounds terrible, but it seems to me that nobody will let it get that bad. It's infeasible to support 70+ browsers simultaneously; no dev shop can afford that. So they would either pick versions or choose some common set of features to support. If this meant that IE users got crappy experiences, despite developers' best efforts, people might finally start ditching IE. (A man can dream, can't he?)

But I think the IE team will find a way to prevent this.

</comment><comment><USER16> IE6's entrenched position came from the fact that (a) it was the latest version of Internet Explorer for a _huge_ amount of time and (b) its status as the IE dead end for Win2k and below.

When IE7 came out, any company that still had any Win2k machines had to keep designing with IE6 in mind if they wanted their new apps to work on all their computers. (I'm making the assumption that if they were relying on IE previously, they couldn't just switch to Firefox or something).

Now, IE8 I think most people can accept is going to end up in IE6's current place. It's the IE dead end for XP, a hugely popular OS. But IE7? None of those companies that don't upgrade upgraded to IE7. Home users that upgrade will also have installed the IE8 upgrade. So you're left with what? Unpatched Vista installations. These are much rarer than unpatched XP installations simply because Vista had a shorter lifespan, and Windows Vista to 7 is sufficiently undramatic an upgrade for the types of people who would take years to go from XP to Vista.

So so far we have:

      - IE6 will drag on as long as XP does.
      - IE7 won't last particularly long. While it's popular now,
      earlier Vista computers will be replaced in the close
      future (2-3 years), causing it to lose market share to IE8.
      - IE8 will have a long lifespan, although probably not as long as IE6.

IE9? IE9 has never been shipped by default with any version of Windows. That means anyone who installed it did decide to upgrade. These users will likely upgrade away, meaning in the future, IE9 will be even more of a non-issue than IE7.

IE10 will likely also go the way of IE7. While it will be installed by default on Windows 8, the amount of dramatic changes in W8 will scare off many of the companies that are slow to upgrade.

So in 5 years time, what versions of IE will realistically you need to support?

      - IE6 (maybe - probably, hopefully, enterprise only at this stage)
      - <USER2>
      - IE10 (enterprise will never use it because Win8 is scary and different to them
      so for home users only)
      - IElatest-1 So IE13 or something?
      - IElatest IE14 or something.

Needing to support IE6 and IE10 will likely be mutually exclusive, so that's 4 versions for sites targeted at home users and 5 for sites aimed at both enterprise and home users. Still ugly, but far from 72. And all those versions will be dead in the timescale that the article is using. Insofar as IE6 will ever die, anyway.

IE6 for home users will be dead at that point. Most of those old early XP computers will be "broken" and replaced, even if "broken" is just slow and annoying. Using XP in five years will be like using Win98/Win2k. Yes, people do use them. No, they aren't a large enough group for most to worry about. I even have a small amount of hits from Netscape 6. I haven't a clue what my page looked like for them, and don't care.

In theory, if even IE is aiming for at least yearly releases from now on, no future IE will end up in the position that IE6 is in, and that IE8 will find itself in, as upgrading your browser frequently becomes a fact of life. The compatibility modes will be much less important too, as the shorter lived the browser, the less likely that the compatibility mode for it will ever be used.

(Sidenote: Sorry for the kludgy lists. HN has no proper formatting for them, and they were causing horizontal scrollbars)

<comment><USER17> IE6 is down to 1.25% in North America. It's dead. Please stop supporting it so people really get the message.

IE7 is 5.25%. Probably slow moving corporations. Some of these guys won't upgrade to IE8/IE9 until they're forced to. So, let's stop supporting IE7 so they're forced to upgrade.

IE8 will be around for a couple of years.

IE9 is around 11.5%. Probably consumers who will gladly upgrade to IE10.

[http://gs.statcounter.com/#browser_version-eu- monthly-201008...](http://gs.statcounter.com/#browser_version-eu- monthly-201008-201108)

<comment><USER18> _IE6 is down to 1.25% in North America. It's dead. Please stop supporting it_

I wish. Our B2B ecommerce system has 34% IE6 usage, as of last week (although this has shrunk by half over the past year or so). I cannot tell 1/3 of our users to shape up -- especially since the ones that aren't upgrading are doing so because they're so big it's incredibly difficult for them. In other words, the ones still in IE6 are also the 800lb gorilla customers, to whom we can't make such demands.

<comment><USER19> How well would they respond to enticements instead of demands? I'm thinking something along the lines of "get these new features for free if you upgrade to an HTML5-capable browser."

<comment><USER20> Yep, progressive enhancement. Have features that only show up for modern browsers, and announce them separately or at the top of any upgrade/version announcement or changelog.

</comment></comment></comment></comment></comment><comment><USER17> "Doctor, doctor it hurts when I have to support 10 versions of IE"... errr... "Then don't that!"

Only support the last two version. Warn people who come to your site that they are using an outdated and unsupported browser. Point them to Chrome, Firefox and Opera, which are all free.

Cut the Gordian Knot:<http://en.wikipedia.org/wiki/Gordian_Knot>

<comment><USER10> As IE6 has died, I think we've kinda lulled into some sort of complacency and I don't see heavy campaigning for browser upgrades currently.

I'd be happy to see it, and like I mention, prompting a IE7 user to upgrade to IE9 is currently just irresponsible.

</comment></comment><comment><USER21> > Meanwhile, you won't have to worry about supporting Firefox 6 or Chrome 13 > in November.

You sure about that? Just because they're not officially supported doesn't mean a significant number of people won't still be using them.

<comment><USER22> As of about a week ago, when Firefox 6 was the current release, the Firefox numbers looked like this (source is [http://groups.google.com/group/mozilla.dev.planning/msg/d1d4...](http://groups.google.com/group/mozilla.dev.planning/msg/d1d4aead06dfe1bb) ):

      Firefox 5 is < 10% and dropping.
      Firefox 4 is < 5% and dropping.

Those are percentages of Firefox market share, not overall market share. So those correspond to somewhere around 2% and 1% of overall users respectively. Note that in November Firefox 6 will be in the position of Firefox 4 right now.

Also from the same post:

      The uptake curve got steeper between 5 and 6, which means
      more people are updating faster.

<comment><USER23> "The uptake curve got steeper between 5 and 6, which means more people are updating faster."

You have to wonder how much of that is a selection effect. Since there was a change in the upgrade tempo in firefox, you'd expect to see the uptake curve get steeper even if overall user behavior hasn't changed, because the users that were on 5 when 6 came out would tend to be the more adventurous ones.

Edit: in other words, ff 5 didn't have as much time to accumulate less- adventurous users as ff 4 did, so the 5->6 transition will appear faster than the 4->5 transition.

<comment><USER22> Yeah, that's a good question. It's hard to disentangle the effects given the available aggregate numbers. We'll see how things look going forward.

</comment></comment></comment></comment><comment><USER24> Honestly, IE doesn't worry me anymore. Chrome does. Seems like every month there's new Chrome-only experiments, and Google provides Chrome-only extensions like offline Docs. Is it too much to ask for cross browsers sites?

</comment><comment><USER25> FUD - you don't have to support every browser. And it's especially disingenuous to say that if you're developing websites/web applications you should care about, say, IE20 users running in IE 5 compatibility mode.

<comment><USER26> I had a similar thought, but as the author points out in a thread here, it _is_ still largely legitimate for library authors.

</comment></comment><comment><USER27> I think that this article puts a large amount of speculation that M$ will continue to operate the same way. While I dont think anyone wants to BET on them doing the right thing, the people upstairs do understand money, and they also understand two of their biggest competitors (Google and Apple) both put out better browsers than they have. IE9 showed that they at least understand the importance of the web browser, and I would hope they would continue along that path with 10. Another thing is that web browsers are rapidly changing and evolving, I know Google is involved with a program now that allows C++ to run natively in the browser. In 2019, browsers could be COMPLETELY different than they are now. Backwards compatibility could become a forgotten term by that point, or browsers could operate totally different than they do now. I think a lot of what was written is true as far as the pain of past browsers, but speculating on the future is often a fool's errand.

</comment><comment><USER28> I thought this was interesting.

<http://caniuse.com/#search=flexbox>

IE isn't going to have advanced CSS3 support until version 10! However, Chrome, Safari, Firefox, Mobile Safari, and Android browser all support it already. It just seems that Microsoft is incapable of staying on the edge.

<comment><USER29> The important part on that page is: Working Draft. Microsoft has committed to supporting standards, as soon as they are standards. It's certainly arguable whether it's a good idea to implement draft standards that people write HTML for that then change under them.

Also, this kinda seems like cheating: "While only recently a W3C specification, this system has been in use for some time by Mozilla and Apple for interface purposes." So they codified something that Mozilla and Apple were already doing, then said that older versions of the browsers already supported the non-existent standard. Impressive.

<comment><USER30> _"Working Draft. Microsoft has committed to supporting standards, as soon as they are standards."_

As you can see in the example pixelcloud cites, Microsoft does in fact implement features based on working drafts. They are already doing this with CSS3 transforms and will be doing so with CSS3 gradients, animations, transitions and flexbox. Therefore, that doesn't actually appear to be the issue at all.

 _"It's certainly arguable whether it's a good idea to implement draft standards that people write HTML for that then change under them."_

Well, we are discussing CSS here, and that's what vendor prefixes (which Microsoft uses, too) help avoid.

 _"So they codified something that Mozilla and Apple were already doing,"_

This is basically how the CSS3 standard progresses. Browser vendors implement a vendor-prefixed feature, and that feature works its way through the standards process. In fact, Microsoft does the same: <http://caniuse.com/css- grid>

</comment></comment></comment><comment><USER12> The thought that occurs to me is that the adoption graph has a lot less to say about the suckage of supporting IE6, and a lot more about the suckage of being a Microsoft user.

Users of other browsers are on systems and/or workplaces _which allow them to upgrade their browsers within reasonable time as new versions come out._

The MS-dedicated shops (and yes, I'm aware that most are large hidebound organizations, enterprises, and/or government entities) _are stuck in their own labyrinths of fragile, massively interdependent, legacy systems._

This suggests to me that the modern vs. legacy browser war may actually be a proxy for ossified vs. agile organizations. There's still a great deal of power in the ossified side, but it will be interesting to see how comparative advantage plays out over the next 5-10 years (assuming the zombie apocalypse doesn't strike first).

</comment><comment><USER31> IE is out of step with the other browsers and no longer has a majority market share.

So there's two options: 1\. Innovate quickly and have access to amazing new browser features, but only cater to 60% or so of the market. 2\. Support 100% of the market, but with considerable more effort (slowing you down).

Both approaches are legitimate. I prefer the first one, but the users who can't use my sites are going to want something equivalent for their outdated browser.

</comment><comment><USER32> Briefly: facebook timeline is terrible. Even Chrome can hardly cope with all the javascript and reflowing as you load a profile page. There's no way in hell IE6 on XP will be able to cope with it -- the rendering engine, OR EVEN the cpu. Maybe that's the whole idea - Facebook could be Microsoft's best way of forcing people to abandon IE6 (and so XP). Semi-seriously, semi-approvingly I ask: Conspiracy?

<comment><USER33> I don't think Facebook has supported IE6 for a long time, at least that was the case when I tested it 6 months ago.

<comment><USER32> you're probably right and I didn't know that. But all of what I said probably applies to ie7 or even 8.

</comment></comment></comment><comment><USER34> <http://www.sitepoint.com/browser-trends-september-2011/>

IE 7 is less than 5% market share now, almost the same as IE 6. I don't see how this predicts a future with 72 versions of IE. And how is this any different than Firefox? I am running Firefox 4 on my office computer - can't upgrade because of IT policy.

</comment><comment><USER35> You're wasting your time if you worry about legacy browser support. Period. For every legacy browser out there--a number which only grows in spurts when a browser becomes "legacy"--there are maybe a 1,000(,000) shiny new browsers being shipped daily. Which do you care about? A stagnant legacy count, or a growing demand of new, mostly compatible, mostly upgradable browsers?

</comment><comment><USER36> When I first read that there are 76 browsers to support, I was thinking... Hmm, yeah this versioning thing is going out of hand. But it was Chrome + FF + Opera + Safari + 72 versions of IE. Seriously? Projecting all the way to IE20 (2022) with a compatibility mode between any two versions of IE?

</comment><comment><USER37> Help me understand this, is the issue that IE users are not willing to upgrade to newer versions? or is it that Firefox/Chrome force users to upgrade while IE doesn't?

Why is the fast release cycle a problem for IE but not for Firefox and Chrome? why are the adoption charts different for IE than the rest?

<comment><USER38> The issue is mainly with the large companies, who primarily seem to be using IE. Due to their size, they can't auto-upgrade without incurring massive costs.

For the average consumer, it's not really a problem.

</comment></comment><comment><USER39> _So in a few years from now, you'll be supporting one version of Chrome, one version of Firefox, one of Opera, (probably) one of Safari, and ten versions of IE._

I think the nightmare scenario couldn't possibly play out this way. We've all seen what really happens when there are too many browsers to support; web developers drop all pretense of supporting the least popular browsers, which would in a case like this be Opera, Safari, and maybe Chrome. And sites put up banners telling users to upgrade to the latest version of IE.

</comment><comment><USER40> "Personally, I'm totally happy supporting the latest version of each of the five browsers."

Yeah, so would we all. That's not really an argument.

</comment><comment><USER41> The Google Chrome version adoption chart very much drives home the difference between chrome and IE!

</comment><comment><USER42> a dose of reality, and it's really a shame.</comment>


Ask HN: Is Ruby on Rails still worth learning? - <AUTHOR> I'm looking to learn more about web software. I like the all in one approach of the Rails framework, but fear it may be losing popularity. Any thoughts? If you were to advise someone today what the best approach to learning web development would be, what direction/resource/book would you recommend? <comment><USER2> The answer is probably that parts of Rails are worth knowing, and other parts aren't.

ActiveRecord and the Rails Controller/Model/Routing system are as good as anything in the serverside framework world. A few years back people might have started saying that AR was in danger of being obsoleted by "modern" databases, but SQL (and particularly Postgres) has come roaring back, and AR remains one of the best (arguably the best) SQL ORM.

At the same time, there's a lot of mechanism in Rails that is aimed at front- end work; templates, different template engines, helpers, the inscrutable asset pipeline. This stuff, not so much anymore. The energy you'd put into learning how to do idiomatic front-end in Rails, you should instead put into something like React (probably: into React).

People with a visceral "No" reaction to your question are probably thinking of what would happen if you started with a couple Rails books and tutorials and just went to town building a 2012-era idiomatic Rails application. Don't do that! But as an API server backend, Rails is fine, and does some things better than other platforms.

For whatever it's worth: we see a lot more Django today than Rails. 5 years ago, it was the opposite. People probably wouldn't recoil at the prospect of you doing an idiomatic Django application, even though it's not that much different than an idiomatic Rails application.

<comment><USER3> Why React over rails front-end? It seems like it adds undue complication. What's the real benefit? Basecamp works great and it's a rails front end. Rails make full stack development pretty easy.

<comment><USER4> React buys you two things: (1) reusable components (2) React Native

[https://thinkster.io/tutorials/what-exactly-is- react](https://thinkster.io/tutorials/what-exactly-is-react)

It's major criticism: there is a kernel of truth in the joke that React is a dressed-up PHP (in the sense of how you put the components together)

Some other options are Vue and Elm.

<comment><USER2> It's been a long time since I wrote or even had to look at PHP, but I have done work in PHP. I use React constantly. I do not see any similarities between the two, like, at all.

<comment><USER4> Yeah, I was shocked when I first heard of it. But when I thought it about it, it makes sense: [https://www.reddit.com/r/reactjs/comments/58wmnz/so_reactjs_...](https://www.reddit.com/r/reactjs/comments/58wmnz/so_reactjs_is_basically_just_clientside_php/)

<comment><USER4> Here's another comment from that reddit thread:

"If you're at all familiar with the history of React, there's actually some amount of truth to this. React grew out of an internal PHP extension at Facebook called XHP. See the recent post describing React's history at [https://facebook.github.io/react/blog/2016/09/28/our- first-5...](https://facebook.github.io/react/blog/2016/09/28/our- first-50000-stars.html) for more details."

"That said, the parallels only go so far. PHP is frequently rather unstructured, while React lends itself to some very specific structures. I don't think I'd necessarily say that PHP typically involves "recursively breaking down parts of the page". But sure, some similarities. (Then again, just about anything that involves template-ish work has some similarities... )"

<comment><USER2> That blog post section describes JSX, not React. JSX is just a notation.

</comment></comment></comment></comment></comment></comment></comment><comment><USER5> I started learning Ruby/Rails early last year. After building a couple projects in Rails for some clients, I switched to learning Elixir/Phoenix instead. Rails has a lot of magic and implicit behavior you need to learn to use effectively. I still love Ruby; the ecosystem is very mature and stable and the language is just so damn expressive.

I switched largely because of the applications I wanted to build were very 'Reactive' and message/event driven. Elixir being an Erlang/Actor-Model derivative with the expressiveness of Ruby was a perfect fit.

Elixir's ecosystem and community hasn't had as much time to develop as Ruby, but it's still very capable and you're not going to run into scalability problems.

If your goal is to skill up and get a job asap, maybe Elixir isn't ready yet, but I'd pick it over anything else to build a greenfield application in.

</comment><comment><USER6> If you want to

\- be very employable => JS/Express/[a-myriad-of-other-things]

\- be able to do anything (including trending AI/ML) => Python/Django (you won't be as productive as with Ruby/Rails and won't the same happiness experience [in regards to web])

\- be very productive in Web env & enojoy your time => Ruby on Rails

<comment><USER7> How does working with Django translate to being able to work in ML? Merely due to Tensorflow having a python interface?

<comment><USER2> It's a running joke at my company (we consult for startups) that no matter what stack they build on, they'll always have a small team of people writing in Python for data science. Which is presumably where that's coming from. It is indeed a sort of de facto standard.

But that's not at all to say that learning Django or Python will get you a data science job; the underlying domain-specific data-science stuff is much harder to learn and qualify for than the Python is.

</comment></comment></comment><comment><USER8> _Usual personal opinion caveats_

Ok, simply rails is a tool. It is a well worn tool. Can do a lot of things and a lot of people know how to use it. Learning how to use it has been done many many times before so the path to competence is really smooth and straight forward.

I think it is worth learning because: 1) the community, you would be hard pressed to find a more diverse, welcoming, non-neck beard programming community. 2) resources, there are a lot of them. You will not encounter a problem that someone hasn't solved for 3) fun, ruby is really nice and doesn't fight you. Some features are debatable (meta programming, everything is an object, it's GIL implementation etc) and I think all dynamic languages downsides are most noticeable in large code bases. But for your stated use case it's great.

I strongly recommend the hartle rails tutorial. I convinced a friend to drop out of his math PhD and go through it. Do I think he will stay a rails programmer? No, but picking up python is a cinch after rails and there is no equivalently good python tutorial for teaching technical fluency in web dev that I am aware of.

Best of luck!!

</comment><comment><USER9> Rails is a good framework and Ruby is a great language. I still use both. However, given limited time, I would advise someone new to learn Javascript / Typescript & a framework based on that instead. Why?

1\. You will need to learn it anyways

2\. It's powerful being able to use one language for both the front and back end. Context changes harm productivity.

3\. Javascript & Typescript are the future and both are evolving really fast.

4\. The Node.js ecosystem is already pretty mature with a lot of 3rd party libraries.

5\. Performance is really good compared to languages like Ruby, Python, or PHP. For near the same simplicity and terseness, you get something with way better performance.

The only downside for beginners is that while the Nodejs world has a ton of libraries and frameworks, there isn't really a dominant framework similar to Rails that provides everything and the kitchen sink as well as a single 'right way' to do everything. The closest thing is Express, but it's really lacking; it's similar to Sinatra. Having to deal with a ton of possible choices and directions for development is just terrible for beginners, which is why Rails is still worth it to learn as your first framework.

</comment><comment><USER10> Yes, of course it's still worth learning. Whether you learn Rails, Django, or anything else, the concepts will apply pretty well for any web framework.

I've been making screencasts for Rails developers at GoRails ([https://gorails.com](https://gorails.com)) showing how to build various features of websites in Rails.

If you're a beginner though, I would first recommend the Rails Tutorial - [https://www.railstutorial.org/book](https://www.railstutorial.org/book)

<comment><USER11> I mean, learning X is an opportunity cost. Not dismissing your answer, but I guess we could rephrase the question: "Is Rails worth learning instead of X", where X can be some other popular frameworks. Or said differently, both for newcomers or more experienced devs, why do you think Rails is worth learning instead of some other web framework?

<comment><USER12> Rails influenced some other popular web frameworks, and I feel it's still faster to build some types of web apps in Rails. I'd think you could cover more concepts sooner and then translate what you've learned to other frameworks as you need them.

</comment></comment></comment><comment><USER13> I was just talking about this with my co-workers. Rails has so much built in and has been refactored and cleaned up so many times that, if you are just trying to build a web application with a reasonable authentication system, it's a great platform to know.

It's very fast to first real web app request (not just a hello world response) and many of the concepts will translate to another platform.

</comment><comment><USER14> I'm always surprised I like Rails. It's my guilty pleasure. I find languages like Elm, Racket, and Elixir to be much more sane and exciting than ruby. And I find the design of frameworks like Phoenix and Yesod to be very elegant when compared with Rails. And at least in theory, I like the idea of composing a bunch of libraries together into an app rather than using a big 800 pound gorilla framework like Rails.

But in practice, I'm more productive will Rails than anything else. I've spent most of my time the past few years with other languages and frameworks, but I'm still more productive with Rails than anything else when making webapps.

Of course, there is a lot of understandable excitement these days around SPA tech like React, which you should probably use on the frontend. Just set Rails to API mode. The productivity of Rails is all of the useful backend features that have been packed in. Out of the box, you have database integration, migrations, data validation tools, email sending, web sockets, background jobs, file uploads, and a dozen other features, all wrapped up in a simple architecture. Simple to integrate gems can add pretty much any feature you need, like authentication, graphql, or search. On top of that, the wealth of documentation and example code is really incredible.

And since Rails projects all have the same core and architecture, most knowledge you gain on one Rails project is transferable to any other rails project. I wish I could say the same for my work in React projects, for example. React projects often use dozens of other libraries, and each project requires me to learn that project's unique set of libraries, their architectural decisions and so on.

If you want to get hired right now? Learn React, redux, and friends. But if you want to MVP a project and need something for the backend, Rails all the way.

</comment><comment><USER15> Depends:

* Do you like to be able to build things fast?

* Do you prefer not having to reinvent the wheel?

* Do you care if it's not the new hotness?

If you answered no to any of those, run away! Rails is mature-ish. It's boring now. Its ecosystem is stable. Your sanity won't be tested.

Reads...

* Michael Hartl's Rails Tutorial is probably the book you'll want to read to get a simple grasp on Rails (it can be overwhelming).

* 99 Bootles, POODR (Sandi Metz)

* some RSpec book

* Finish it off with [https://rebuilding-rails.com/](https://rebuilding-rails.com/)

<comment><USER16> Is "rebuilding rails" still relevant? The website has a 2010-ish design vibe and it seems to talk about rails 3 being cutting age while we're now at rails 5. One image has (c) 2012.

Didnt know about the book, so I'm interested, but I can't tell if it's worth buying because of the above.

<comment><USER15> It's very much still relevant. It won't give you very low-level details but it'll explain a lot of the metaprogramming (others call it magic) that Rails has.

</comment></comment></comment><comment><USER17> Yes, absolutely. It's a very mature and productive framework with a vibrant community built up around it. It integrates with webpack so you can have whatever frontend you like. There's plenty of work. Performance and scalability are big focuses for the future Ruby and Rails, respectively, which covers most people's gripes.

It never hurts to know a few tools, but at the end of the day if you need to crank out a webserver Rails is top notch.

</comment><comment><USER18> I'd definitely say no. Going from little knowledge straight into Rails teaches terrible habits imo, and indeed it doesn't tend to be used for new projects much any more.

When you're learning to find your feet with software engineering, I'd strongly recommend avoiding languages where the emphasis on everything being "magic". It doesn't help you learn how things actually work.

<comment><USER19> So, what actual book/tutorial would you recommend for somebody who wanted to learn web development? Regardless of the problems with Rails itself, what's a better learning path that the Rails Tutorial?

<comment><USER18> I wouldn't. Just need to get stuck in and keep Googling anything you don't understand. Best thing you can do is find a friend who knows a bit about programming to show you what they know.

</comment></comment></comment><comment><USER20> Yes. But any modern web framework would also work. The patterns and practices you will learn from any of them will be mostly comparative.

What will really help you the most is learning a second tool chain after the first. This will introduce you to new and differing patterns that allow you to see the pros and cons so many here are stating.

You'll find most people have changed frameworks and languages throughout their careers. You have to with ever evolving technology. So X vs Y doesn't matter too much. At some point both could be obsolete.

The goal you seem to be after is learning web development in general. While there could be any number of paths, I would recommend whatever one you have the most resources for.

If you know developers that you can have help mentor you and they use X... then use X. Because nothing beats having a 10 minute explanation when you are learning compared to a blog post.

If you don't have in person mentors, then find X framework that has the most resources. You'll find the more stable frameworks tend to have the most documentation, go figure.

I'd also start out with a full stack framework. This is because you will already be learning so much that it can be overwhelming. Don't lose motivation to continue learning programming by trying to learn every little piece of web development. Just get something simple working. Then use libraries to add functionality. You'll get more excited having built something. Then go start to see how the library works internally and start your deep dives into core functionally apps have to have. Like authentication, authorization, validation, databases, etc.

The biggest problem I see with new or prospective developers is analysis paralysis. Pick anything and build something. If you aren't having fun you won't keep at it.

As far as employability... it's the principles you learn from building something that matter more than the framework. At lots of companies you won't even find language or framework in the job posting. This is because they understand someone who had learned the strengths and weaknesses of patterns will be more valuable. Those are harder and take longer to teach than a second language to someone. While already knowing the toolset never hurts, it often isn't a requirement.

P.S. I'm biased... use Ruby and Rails

Update: corrected protective to prospective.

<comment><USER21> I would upvote this post twice if I could.

Rails is probably still the best implementation of a full-stack framework, and I agree that full-stack frameworks are are the best way to learn.

Despite working for a Rails shop for a long time, I would probably not recommend Rails itself for completely new programmers anymore, just because they would probably be better served learning Python than Ruby these days.

</comment></comment><comment><USER22> For early stage development, Rails is still the best. No ORM tool out there is as powerful as ActiveRecord. Front ends are nowadays built more with React/Redux, which is well supported via Webpacker. And for basic admin pages, regular controller calls with validations and ERB/Haml/Slim templates works great. And GraphQL is fully supported via gems.

When you look for performance for microservices, Go or Scala are better. But that's when you are beyond the first 2 years and 25 developers and have the cash to invest

</comment><comment><USER23> Yes. It's pretty useful for building most kinds of common web services. Lessons learned will translate well to othe tools, and in particular it will help you to avoid making some common mistakes while getting to grips with the nuts and bolts of web applications.

Don't panic about it "losing popularity." Tools and techniques learned using one framework are pretty generally applicable to others.

</comment><comment><USER24> I used to be a Rails developer, but in today's JS ecosystem I've found most of it can be replaced by full-stack JS.

In particular with an EmberJS front-end if you like the EmberJS convention over configuration methodology.

</comment><comment><USER25> Yep, absolutely. It's a very productive environment to build in. If you want to get something infront of a user quickly and not get stuck in configurations, webpack scripts and so on, go with rails.

</comment><comment><USER26> "Is Rails still relevant in 2018?"

306 points by bdcravens 49 days ago

333 comments

[https://news.ycombinator.com/item?id=17856314](https://news.ycombinator.com/item?id=17856314)

</comment><comment><USER4> RoR, for all of its flaws, influenced many other frameworks. It is still very popular, though I'd also say, it is on a slow decline. The takeaways are:

      1. How to create a good experience for developers

      2. Taking care to refine syntax, patterns, and architecture

      3. If you understand how the Rails is put together, you'd generally know how many frameworks are put together.

However, there are some other options.

      1. Many Rubyists and Rails developers had jumped over to using Elixir and Phoenix; that platform

      2. Others have started experimenting with Rust, Go, Crystal, etc. after knowing the flaws of the Rails platform

      3. However, the Rubyists who jump to a different platform often bring in the things they learned from Ruby to apply to the new platform. For example, Elixir is primarily built around a powerful macro system that allows for refining the syntax, while taking advantage of what the Erlang/OTP environment.

</comment><comment><USER27> I work daily in rails and have for years. It's a great platform to learn from.

Honestly, I don't _enjoy_ using the front end parts of Rails, and even on the back end side of things there's a lot of non-standard things that are good to do in order to make an actually scalable and long-lived app. But that doesn't mean it isn't worth using.

</comment><comment><USER28> Wow. Really going for a trigger with the title.(you should get a lot of activity)

The answer that you will unconditionally see to this question will be "it depends"... I would get more specific with your question so that you can extract a bit of wisdom from the answers.

Rails is and has been a dominant web framework for the last ~10 years, dhh and the people working on it have crafted a wonderfully useful tool, with all sorts of lessons hidden inside the code. Ruby is a great language... and all of these things provide wonderful reasons to learn it.

With that being said, I don't use it anymore. and I'm not going to ever go back to it unless there something out of my control. ¯\\_(ツ)_/¯

Do I recommend it? ... It depends

<comment><USER29> Curious as to whether you have found a better Rails-type framework or have moved on to a different type of dev work that you prefer. Any recommendations?

<comment><USER28> In a "philosophical" move I've gone into the micro-framework realm for web stuff, and of late that means mainly a Serverless Node.js (w/ ES7) set up which is similar to the OpenAPI/swagger (w/ koa) stuff I was doing a bit ago. Also some flask.

I'm mainly trying to do things with as little code as possible that are lightweight with almost no devops. Things like static site generators, Vue w/ Serverless Framework, Flask... which do have limitations... but they are tradeoffs that I'm comfortable with, and I know the work arounds.

At work for my last two W2/Employee gigs our main codebases were Laravel and Rails. Lots of advantages, but they come with tradeoffs.

My main recommendation is that you need to find what fits for your situation. Frameworks, IMO, are more than a set of technical choices they are cultures and shared sets of values. Which is why Rails didn't really fit for me. I'd argue that I'm a fair to mediocre developer... and I care more about the thing I am building rather that what I am building with. So I try my best to keep the code out of my way. JS kind of helps me do that because I don't need to flip my brain around so much between syntax, and it has arguably the most resources for getting over challenges. What I lose is speed (compared to Go, Java, C) and that I have to be really good at evaluating resources/ repos (Rails/ Laravel pretty much do this for you).

</comment></comment></comment><comment><USER30> I think you should give it a try. Rails made me a better software architect and showed my the importance of writing expressive elegant code. It might have lost some market share to other techs (Node / Elixir) but it's still the original.

</comment><comment><USER31> I think you should as your first web framework. Ruby is fun to write, and it's easy to find and understand examples for Rails (even across versions). Rails is more opinionated so allows you to think less about project structure and more about actual business logic (might be seen as a benefit for a beginner)

The big ideas from any of the popular web frameworks (rails, django, express, etc) will be shared between the rest of them. It's really more of a question about which language do you want to use.

If you already had experience with web MVC, I would recommend something more exotic like elixir phoenix instead (1.4RC released today)

</comment><comment><USER32> I was a Rails dev for the past 7 years, switched to a React position a couple months ago.

There was a lot of hand wringing a few years back that Rails was quickly losing popularity, but gauging by my recent time on the job market it is still very hot. It seems like I had just as many recruiters contacting me for Rails positions as they did React. I somewhat suspect this is because many people transitioned to other things and it's harder to find experienced devs.

As many others have stated it's a mature ecosystem and there's plenty of great learning material out there.

<comment><USER33> But job market varies in every market. Rails aren't seen much anymore in EU, SEA Tech Hub and China, No idea on Canada or AUS. Japan seems to use Ruby much more in non Rails application.

</comment></comment><comment><USER19> I would say yes, because I don't know of a better learning resource for "learning web develeopment", especially for somebody starting at zero, teaching oneself, than the Rails Tutorial: [https://www.railstutorial.org/book](https://www.railstutorial.org/book).

Rails aside, what would be the best tool for "learning web development" starting from zero?

I ask because people ask me and so far I've been sending beginners to the Rails Tutorial.

</comment><comment><USER34> I don't have as detailed an answer as several of the other commenters here, but as someone in the job market at the moment I see a decent amount of Rails work floating around.

Another framework that seems to have been burgeoning in enthusiasm lately is Phoenix, built in Elixir which is a Ruby like syntax. The neat thing there is that it introduces a ton of interesting OTP concepts borrowed from Erlang (both Erlang and Elixir compile down to bytecode for the same virtual machine, the beam).

</comment><comment><USER35> I'm still most productive in Ruby on Rails, I learned it after previously using Go, PHP, and Python (Django and Flask) for web development. Far and away Rails allows me to be more productive, and it's still being actively developed. I've used Node.js and some other frameworks since, but personal projects always come back to Rails.

It's up to you, what I will say, is Rails is (in my opinion) the easiest to get started with and easiest to maintain.

</comment><comment><USER36> The question is why do you want to learn something - because it is marketable or because you will learn good practices in software development?

</comment><comment><USER37> The question isn't "is it worth learning" it's "is it worth learning next". What do you already know?

Focus on learning theory and standards (e.x. HTTP, websockets, MVC, security principals) and learning tools becomes easy enough you won't bother asking us if it's worth the time investment.

</comment><comment><USER38> Pretty much every programming language community has server side framework(s) which is better or close to the features provided by RoR.

[https://en.wikipedia.org/wiki/Comparison_of_web_frameworks](https://en.wikipedia.org/wiki/Comparison_of_web_frameworks)

</comment><comment><USER39> No. It already has a large number of experienced enthusiasts chasing a diminishing amount of work.

</comment><comment><USER40> It's not directly related, if I have the same question but change ruby and rails with php and laravel. What's your answer? I saw many early stage startups build their MVP using laravel.

<comment><USER41> I use laravel daily... normally as a backend to SPA style apps, with Vue on the frontend. It's a great workflow. I've tried and tried to move to nodejs as a backend, but there's just too many options, and I feel like there's no best practices there.

Basically it feels like php did back in 2012. There wasn't really a 'framework'... there were a few popular ones: codeigniter, symfony, zend -- but until the entire dev base flocked to laravel you really didn't have that community.

Then laravel kept just becoming stronger and stronger, and then vue came about and fit perfectly along side laravel. JS has no real backend that the entire community has adopted. I mean a large part of the js community doesn't even use backends they use serverless or BaaS like firebase, and there's definitely no really good full-stack frameworks esp since you now need to choose one that fits your 'flavor' (vue/react/angular).

Whatever you do, you WILL probably want to learn react or vue, I prefer vue, but that's just my preference. Vue/react are very employable skills right now. React more so, but vue is rising in popularity and I think will surpass react (I hope)...

</comment></comment><comment><USER42> I feel that rails is still a good framework to prototype, and grow a business from scratch.

[https://www.rubycademy.com/](https://www.rubycademy.com/)

</comment><comment><USER43> I feel like I see a post like this every 6 months.

</comment><comment><USER44> Yes.

</comment><comment><USER45> No. That ship has sailed. The new runtime is in the browser. Learn about wasm and matrix-multiply-add.

</comment><comment><USER46> crystal

[https://crystal-lang.org/](https://crystal-lang.org/)

<comment><USER47> question asked about web software, is this not more of 'cutting edge language experiment'?

</comment></comment><comment><USER48> No.

</comment><comment><USER49> Yes.

</comment><comment><USER50> Yes.

</comment><comment><USER51> Go take a look at OutSystems. Www.outsystems.com</comment>


The robot will see you now: could computers take over medicine entirely? - <AUTHOR> https://www.theguardian.com/technology/2018/jul/29/the-robot-will-see-you-now-could-computers-take-over-medicine-entirely <comment><USER2> Once they can prescribe opioids, then yes.</comment>


Surprises of the Faraday Cage - <AUTHOR> https://sinews.siam.org/DetailsPage/TabId/900/ArtMID/2243/ArticleID/757/Surprises-of-the-Faraday-Cage.aspx <comment><USER2> Feynman wrote " _The method we have just developed can be used to explain why_ electrostatic _shielding by means of a screen is often just as good as with a solid metal sheet. Except within a distance from the screen a few times the spacing of the screen wires, the fields inside a closed screen are zero. "_

Feynman is writing about _electrostatic_ shielding, not RF shielding.[1] Electrostatic shielding involves a _static_ electric field, as from a Van de Graff generator or other high voltage DC source. RF shielding is quite different. For one thing, it's wavelength-dependent. This is well known; you can block RF with a mesh only where the holes are much smaller than the wavelength. This is in the ARRL Handbook. If this were not the case, wire screens would block light.

JPL's paper mentioned by someone else [2] has a simple formula for a plate with a uniform pattern of holes, derived from waveguide theory. Inputs are spacing between holes, size of hole, and wavelength. They tested this against a range of perforated metal samples. There's a note that if the hole size approaches the spacing, corrections need to be applied. But they didn't, apparently, have to do that for the samples they tested.

The misconception may have arisen because Feynman was writing in the 1960s, before RF in the gigahertz range was a common thing. Other than radar, everything used long wavelengths by modern standards. Treating RF as an electrostatic problem works if the wavelength is much greater than the hole size, because the electric field will be nearly uniform over the area of interest.

(I'm not an RF guy, but I used to work in an R&D facility that did a lot of RF work and had various Faraday cages, some solid metal, some mesh. A big practical problem is leakage at slots - covers, doors, etc. - that don't have RF-tight gaskets or where the gasket has been damaged. Slots can be longer than a wavelength, and thus no longer block RF. Microwave ovens, if they leak RF, usually do so at the door seals, not the window.)

[1] [http://www.feynmanlectures.caltech.edu/II_07.html](http://www.feynmanlectures.caltech.edu/II_07.html) (Section 7.5) [1] [http://ipnpr.jpl.nasa.gov/progress_report2/II/IIO.PDF](http://ipnpr.jpl.nasa.gov/progress_report2/II/IIO.PDF)

<comment><USER3> But the OP is writing about _electrostatic_ shielding too... What makes you think the below section from the OP does not apply to _electrostatic_ shielding?

"The error is that Feynman's wires have constant charge, not constant voltage. It's the wrong boundary condition! I think that Feynman, like me and most others beginning to think about this problem, must have assumed that the wires may be taken to have zero radius. The trouble is, a point charge makes sense, but a point voltage does not. (Dirichlet boundary conditions for the Laplace equation can only be applied on sets of positive capacity.) Since the correct boundary condition cannot be applied at points, I'm guessing Feynman reached for one that could, intuiting that it would still catch the essence of the matter. This is a plausible intuition, but it's wrong."

I'm not an expert in electrical field theory, but a constant voltage boundary condition seems very reasonable to me (and a constant charge one seems less reasonable), also in the _electrostatic_ case.

</comment></comment><comment><USER4> > L1. There are gaps out there.

I had a similar experience. At one point I decided that I wanted to understand, step by step, how Ada Lovelace's Bernoulli program works[1]. There was a few steps that didn't seem right to me but I was sure if there were any bugs in there they would be well-known and mentioned somewhere I could find. This being one of the most iconic and historically significant programs ever written. Indeed I found more than one person claiming that the program was known to be correct.

It took a long time before I could believe that it wasn't just me not getting it, there were indeed a few things out of place and apparently there was just no mention of it anywhere on the web or in any of the research into the analytical engine I could get my hands on.

[1]: [http://h14s.p5r.org/2012/12/bernoulli.html](http://h14s.p5r.org/2012/12/bernoulli.html)

<comment><USER5> Reminds me of Alan Kay's frequently mentioned nugget about Kepler, that he waited for _years_ to try and fit orbits to ellipsis, because, being so close to circles and ovals, _surely_ all the people doing this stuff before had tried ellipsis, and found them wanting? (No, they hadn't).

<comment><USER6> I've been lead to understand that some issues may have been before Tycho Brahe no one had made accurate measurements, especially of the entire tracks across the sky, not just 'interesting' places.

<comment><USER5> True, but according to eg (random Google hit):

[http://galileoandeinstein.physics.virginia.edu/lectures/tych...](http://galileoandeinstein.physics.virginia.edu/lectures/tycho.htm)

"Kepler realized that Tycho's work could settle the question one way or the other, so he went to work with Tycho in 1600. Tycho died the next year, Kepler stole[sic] the data, and worked with it for nine years.

He reluctantly concluded that his geometric scheme was wrong. In its place, he found his three laws of planetary motion"

</comment></comment></comment></comment><comment><USER7> Pretty interesting read. I'd like to know the answer to the 3rd question at the end as well, microwave manufacturers must have known about this all along since the doors embed a chunky piece of metal with small holes and not a lightweight grid of thin wire as one might expect with the "traditional" understanding of the Fraday cage effect.

So did they figure out the theory independently ? Did they design the screens based on measurements ? Maybe there's a patent somewhere that may shed some light on this.

<comment><USER8> Radio propagation is quite a bit like magic, and if you're an engineer making a microwave, you probably really don't care that much about the theoretical underpinnings. The thought process goes something like this:

I have a loud radio source I want to keep contained in a box. I want people to be able to see into that box while it's on. I know that radio waves are blocked as long as the holes are smaller than some multiple or fraction of the wavelength of the radio source.

So what do I do? I think about what's easy and cheap to manufacture while being reliable. I try out a few things and measure the radio leakage. I pick the best solution out of the few I tried.

None of that really has anything to do with the subtleties of theory, the practice is you want something good at shielding that's good for the guys building it.

<comment><USER9> Your post is a great description of the phenomenon that Tableb describes in his book Antifragility, as "Lecturing Birds how to fly" [1] Essentially the argument is: we learn by doing and formalize that knowledge in research. Birds don't need to be lectured on fluid mechanics(drag,lift,etc) to understand how to fly.

[1][http://www.yourparttimehrmanager.com/lecturing-birds-to- fly-...](http://www.yourparttimehrmanager.com/lecturing-birds-to-fly- overreliance-on-formal-education/)

<comment><USER10> And it seems to me a trivial step to then say that formalized knowledge churned through the science leads us to things that are impossible for birds.

</comment></comment></comment></comment><comment><USER11> I, perhaps naively, thought it was a well understood phenomenon. With random references in sci-fi, and a quick appearance in Enemy of The State (movie), I thought it had all been locked down.

It's somehow inspiring to learn how much is there for us to learn.

<comment><USER12> What does "well understood" mean exactly? Ask the average inhabitant of Hacker News and he will tell you that "Faraday Cage the name of a phenomenon whereby a box of metal prevents electromagnetic fields inside", or something like that. But ask him how the strength of the electromagnetic field depends on the wire radius and mesh size, and he might not know the answer.

That said, the answer was known to Maxwell, as the author remarks, although not to the author himself. As is often the case, the problem is in the details. So in a sense, it is a well understood problem to people who know the details well enough.

I'm a physics graduate I did not know the answer, and I can assure you that the average physics graduate doesn't know the answer. In the year 2000 a graduate course in physics contains so much "advanced" physics that you end up learning a bit of a lot instead of a lot of a bit. My contemporaries and I know a lot of physics superficially, unfortunately. Time is limited, and in university you learn what you're fed.

But yes, I agree with the sentiment of your post, of course :-)

<comment><USER13> A second-year Physics student can work out RF shielding using Kirchhoff's diffraction formula, or just looking at the wave equation in the k domain (spatial frequencies). Electrostatic shielding is the hard bit addressed in the article.

<comment><USER12> You didn't really read the post, did you? Keep on winging it mate.

<comment><USER13> I did. Where am I mistaken?

</comment></comment></comment></comment></comment><comment><USER14> > Intuitively, sinusoidal oscillation in one direction corresponds to > exponential decay in the direction at right angles in the complex plane. A > contour integral estimate of Fourier coefficients exploits this decay to > prove exponential accuracy.

I couldn't get past this part. What is the author saying here?

<comment><USER12> Some aspects of electromagnetism are better discussed in terms of complex analysis. I believe the first sentence is referring to this: [https://en.wikipedia.org/wiki/Euler%27s_formula](https://en.wikipedia.org/wiki/Euler%27s_formula) The function e^(i x) is a (complex) sinusoidal oscillation when x is a real number, but is a (complex) exponential funciton when x is an imaginary number. The phrasing "in the direction at right angles in the complex plane" refers to the fact that the real and imaginary axis are perpendicular to each other.

I'm not sure about the second phrase. A contour integral is an integral over a closed path on the complex plane, and there's a theorem that says that if the function and the path have certain properties, the result of this path integral is just some coefficients (called residues). But I'm not sure how that's connected to the rest of the conversation. [https://en.wikipedia.org/wiki/Residue_theorem](https://en.wikipedia.org/wiki/Residue_theorem)

<comment><USER15> The residue theorem implies that you can compute some integrals on the real line by closing up the contour in the complex plane and accounting for any poles that you've enclosed. The trick is to choose your contour so that the contribution to the integral of the new piece goes to zero as the contour gets larger and larger (think of a real piece which goes from -R to R, and a semicircle in the upper half-plane connecting those two points; as R->infty, the real part of the integral goes from -infty to infty). One reason the new piece may go to zero is that oscillating functions on the real line turn in to exponential decay as you go up or down along the imaginary axis (as you point out), so as the new piece of the contour moves up or down, its contribution to the integral gets exponentially smaller.

(This is hard to explain without pictures and formulas, but you can find some examples here: [http://web.williams.edu/Mathematics/sjmiller/public_html/302...](http://web.williams.edu/Mathematics/sjmiller/public_html/302/coursenotes/Trapper_MethodsContourIntegrals.pdf)).

<comment><USER12> I know what it is, how to use it and all that. I just don't know how to make sense of the specific phrase that the parent asked about.

</comment></comment></comment></comment><comment><USER16> I'm still reading the article, so perhaps I am missing something. But it seems to me that Feynman was perfectly entitled to think in terms of point (really line) charges.

By Guass' law, an isolated cyclinder with constant voltage will look to the outside world exactly like a line of constant charge-density. One cylinder among many will be slighly different, because the corresponding line charge will have external voltages superposed. But as the radius of the cylinder approaches zero, those will vanish in proportion to the 1/r voltage from the central charge.

Now the author might have some other way of getting to the same result. But that doesn't mean Feynman's argument was wrong -- it was just different.

<comment><USER12> Let me tell you how I understand this.

I think the most important part of the question is whether the field inside decreases exponentially or linearly with the distance between wires. To the extent that Feynman didn't incorrectly answer with "exponentially", he wasn't wrong.

However, whether the wires have constant charge or constant voltage (across the cross section) is not just a matter of the argument being "different". As the author explains, if you take the wires to have be point-like (in cross section) then Feynman is right in taking the charge to be constant. However, if you want to discuss the scenario where the wires are not point-like, then you have to pick: do you impose that your wires have constant charge or constant voltage? You take ideal conductors to have constant voltage across, and the charge distribution is whatever comes from solving the relevant equations.

But I'm open to be shown to be mistaken though :-)

<comment><USER16> It's absolutely true that fat wires will behave at least a little differently from the point-like wires.

But if you are looking for a physical intuition behind the general mathematical form, then the thin-wire limit where you start. Big-wire deviations are an advanced topic, fit for engineers.

N.B. there's a difference between "thin wire" and "point like". I am saying that _real_ wires, with constant-voltage surfaces will _behave_ like point- like charges as they get smaller.

<comment><USER17> Perhaps I read this wrong, but isn't the opposite story the case? As wires become more point-like, the effective shielding drops to zero. However, when wires become _precisely_ points, shielding becomes perfect?

<comment><USER16> It dosen't drop to zero. It is worse than for fat wires -- but the maths is easier.

It's intutively obvious that fat wires should shield better (there's just more shielding). But the original author is right that it the explanation of _why_ this works is lacking from the Feynman point-like appraoch.

</comment></comment></comment></comment></comment><comment><USER18> Analysis of such problems is usually done using numerical electromagnetic tools, based on finite element method (FEM), finite difference time domain method (FDTD), method of moments (MOM) or hybrid methods. Use of such tools is not a straightforward task, and it takes a lot of effort to create accurate models. Numerical methods are used because apart from very few problems almost all problems of practical interest (such as microwave ovens mentioned in the article) can only be solved numerically.

</comment><comment><USER19> Another example in science that you'd think is well understood, but isn't is water. We still don't know why and how clouds form or why ice is slippery, we don't even know whether liquid water is strictly speaking a liquid and not a crystal some of the time.

<comment><USER20> We don't know why ice is slippery? I thought that was understood as hydroplaning (small amounts of ice melt and then you have a low-friction scenario where water separates the two surfaces). I've read that when ice is cold enough and the other surface (a rubber tire for example) is also below freezing point there is good traction.

Is there a description of this that a layman such as myself with a college degree in mathematics (heavy undergraduate physics) could understand?

<comment><USER21> It may be too basic for you, but I liked this 2005 overview from Physics Today: [http://www.chemistry.northwestern.edu/documents/about/Rosenb...](http://www.chemistry.northwestern.edu/documents/about/RosenbergPhysicsToday.pdf)

The problem with the popularly held "pressure melts the ice" theory is that ice can still be very slippery even at temperature-pressure points that are not explained by that explanation.

It may be misleading to say that ice's slipperyness is "not understood", but it still is definitely an area of active research, with the understanding and theories evolving more rapidly than one might expect for something "obvious".

<comment><USER20> Thank you!

</comment></comment></comment></comment><comment><USER22> There will be a live chat with the author of the article, Nick Trefethen, on Thursday, August 18 from 12 noon - 1:00 p.m. ET through the comments page on the SIAM News site: [https://sinews.siam.org/DetailsPage/TabId/900/ArtMID/2243/Ar...](https://sinews.siam.org/DetailsPage/TabId/900/ArtMID/2243/ArticleID/757/Surprises- of-the-Faraday-Cage.aspx) Be sure to join us and ask any questions of the author regarding this topic!

</comment><comment><USER23> So, intuitively speaking, why does the field decreases with increasing wire radius?

I also don't understand the factor epsilon*log(r). Doesn't that contradict the above statement? (smaller radius should lead to a larger field, not smaller)

<comment><USER12> epsilon log(r) is the "shielding". I suspect that the field inside will be attenuated by a factor of 1/(epsilon log(r)).

<comment><USER23> epsilon is the gap, so either way it should be on opposite side of the log(r). Smaller gap, stronger shielding but smaller radius weaker shielding. Am I going nuts?

<comment><USER12> Hm I guess you're right. I don't know what to tell you. I guess we'd have to have a look at the exact definitions they use in the paper :-)

</comment></comment></comment></comment><comment><USER24> I distinctly remember a conversation with a friend when we were both working together around 1989 which was about the propagation of microwaves and the shielding in microwave ovens. He was an Electronics graduate from Durham University and he said that it wasn't properly understood.

Well, it looks like it is now!

I do find it interesting that my friend knew this, but many senior scientists, even at Oxford University, were not aware of it.

A good illustration of the split between theoretical science and its practical application!

</comment><comment><USER25> This is a fantastic paper. Truly shows a deeper intuition can be gained if a rigorous mathematical description is made. Upon reading it, it seems so obvious how treating wires as point charges would give flaws, and the surprise that the radius is more important than the interwire distance, after seeing the results make sense. Remarkable work.

</comment><comment><USER26> I'm just saying _" Intuitively, sinusoidal oscillation in one direction corresponds to exponential decay in the direction at right angles in the complex plane. A contour integral estimate of Fourier coefficients exploits this decay to prove exponential accuracy."_

Isn't particularly intuitive to me :-). But the answer to the three questions is that engineers are not generally mathematicians, and once something meets the requirements they move on to the next problem. Shielding with wire mesh can be tested with a field strength meter and no math, so if the cage isn't shielding enough you adjust it until it does, and then move on.

</comment><comment><USER27> So, is there a good foundational course on RF? It is more and more important but I have almost no intuition (nor it seems the maths) to approach it beyond "ohh look, three bars of strength, I can rely on IP now"

<comment><USER28> RF is a really big field and it depends on whether you want to approach it from a theoretical or practical direction.

I have a physics background, and all I can say about EM from that point of view is that learning EM without basic vector calculus is a bit like learning mechanics without basic integral calculus: it's more complicated than it would be with the more advanced math background.

One simple example is just maxwell's equations; compare the two forms in this table from wikipedia[1]. With about one semester extra of college math you can use the form on the right rather than the left.

1: [https://en.wikipedia.org/wiki/Maxwell%27s_equations#Formulat...](https://en.wikipedia.org/wiki/Maxwell%27s_equations#Formulation_in_SI_units)

</comment></comment><comment><USER29> I tried to build a faraday cage out of a big tube of aluminium (~10mm thick) with similar caps. Machined so very thin gaps, and I even taped them up with copper tape. The weird thing is it doesn't work. I put a BLE transmitter in there and it reduced the signal strength by maybe 40 dB, but I was expecting perfect containment.

Can anyone explain that?

</comment><comment><USER30> The Faraday cage shields perfectly against electrostatic fields, not electromagnetic fields. That's where the skin depth is important.

<comment><USER12> Very not static

[https://upload.wikimedia.org/wikipedia/commons/c/c0/Cage_de_...](https://upload.wikimedia.org/wikipedia/commons/c/c0/Cage_de_Faraday.jpg)

<comment><USER30> I suppose we have a different notion of shielding. If you look at this page, you'll see the shielding effectiveness dropping with frequency, hence the skin depth.

[http://www.ets-lindgren.com/iSeries-71](http://www.ets- lindgren.com/iSeries-71)

</comment></comment></comment><comment><USER31> next time someone suggests a faraday cage for rf work, I think I'll suggest a maxwell array instead :)</comment>


Ask HN: Start formal group to peer review climate code? - <AUTHOR>

Wanted to see if some people had interest in forming a formal group to vet algorithms used to calculate climate data. In the wake of the CRU emails that included questionable programs written to interpolate temperature data, I think there will be a need for an independent review by coding experts.
Maybe a wiki style project with everything laid out in the open.
For the record, I'm impartial and agnostic about climate change because I haven't seen the raw data or the programs used to make future predictions. I think this whole "consensus of scientists so its right" is BS and goes against the scientific method. Plus, climatologists may be incentivised to spread FUD b/c it brings fame and more grant money - plus their expertise is not statistics and writing code.
A software engineer reviews CRU source code - http://www.youtube.com/watch?v=q_buKNBrpcM
I'm sure some funding would not be difficult to find, given the magnitude of all this.
ClimateCodeReview.org? ClimateHackers.org? ClimateCrunchers.org?... <comment><USER2> One thing I don't get is how people always seem to follow the pattern "I'm unbiased. #{strong_opinion_here}."

Unbiased... really, hop?

For the record: I think that open source + code cleanup + code review is a great idea, and not just for climate science. But it's important to keep in mind that ugly code isn't the same thing as wrong code, and that mistakes in the code aren't automatically become mistakes in the science.

(For example, a poorly written data parser with lots of bugs will not affect the science one bit, if none of the data triggers those bugs.)

So what's your purpose here:

\- To contribute to a community, finding and fixing bugs, making things more readable and robust, etc?

\- To do a little audit to "prove" what you already believe? (I suspect a hint of witch-hunt in the air...)

Edit to fix formatting and add a side comment: This "climatologists may be incentivised to spread FUD b/c it brings fame and more grant money" bit doesn't pass the smell test for me. If this is the true motivation of climatologists, then why aren't more of them going for the fame and think-tank money available to them by expressing dissent? I can't believe that all these scientists are dishonest and greedy enough to lie about the science, but not suitably dishonest/greedy to sell out their peers.

<comment><AUTHOR> I am biased - not about climatology, but having been in grad school and seen it first hand, I am biased about scientists motives, especially when you are competing for millions of dollars of grant money. I also know its easy to fit big data sets to a desired conclusion.

I care about being confident that the data supports the conclusion. I want all the data in the open and open to scrutiny. Whether the Earth is cooling, heating, staying the same - I just want it proven with open source code, not on a consensus of people I don't know using data hidden from the public, with code that I haven't read.

Edit: I am sure the vast majority of scientists are true to the data. And this project will only help reinforce their work.

<comment><USER3> Even if you could get ALL the data in an open and transparent format and were able to scientifically prove that "Global warming is (100% real/fake)" it wouldn't matter because the political/corporate/celebrity forces on the other side would claim that you are "using bad science, corrupt, in the pocket of (liberal elites/big corporations)". Even if you proved that there isn't enough data to prove anything, both sides would say you are wrong.

<comment><USER4> It's still worthwhile.

</comment></comment></comment></comment><comment><USER5> I think you miss the fact that to figure out what scientific code does, you also have to know the science. Yeah, you can look for dumb bugs like the one they show in that clip, but you have no way of knowing whether calculations are correct without knowing what's going on.

I found it disingenuous how they flashed a line of code that says "fudge factor" as if that makes the code incorrect. Unless you know what that fudge factor is for, you can't make that judgement.

<comment><USER6> Climatologists should articulate what adjustments are necessary and why. Popularizers can then make it accessible to laypersons if need be - there is certainly enough interest.

The whole point is that up until now we've been trusting the details to climatologists, and that trust has been broken.

Layer on top the stakes, and also consider that this issue really lies at the intersection of many fields: climatology, computer science, economic, politics; opening this up is the only sensible next step.

<comment><USER5> Oh, I totally agree that it all should be public. I'm just saying that the OP's take that "let's get some professional programmers in there and clean it up" won't work unless they work in close collaboration with the scientists themselves.

</comment></comment></comment><comment><USER7> I'd like to start a formal group to bring back the glaciers and arctic ice cap.

</comment><comment><USER8> The neat thing about being a professional programmer is that you are always working in somebody else's problem domain.

So I wouldn't take the naysayers too seriously. If you can't peer review climate code, you can't peer review financial code, or medical code, or astronautics code.

Sure, you'll need problem domain expertise. But that's a given with any kind of programming. Climate science is no different than any other kind of work programmers do.

I think it's a great idea -- if you can pull it off. But that's a really big "if".

</comment><comment><USER9> I'm definitely interested, not sure about the time.</comment>


A Long Goodbye To Facebook - <AUTHOR> https://om.co/2018/09/01/the-long-goodbye-to-facebook/ <comment><USER2> > I left because it was making me someone I am not — someone who lives life > through the eyes of others.

I agree so much. I was never an avid Facebook user who posts personal life but I was reading over other's lives and that affected who I am, what I should do with my life. Even though I feel I have full control over my life, what I read from FB about my friends changed what I should be doing to be in the current "trend" to belong to the group.

<comment><USER3> Yeah, I agree with that quote so much. I was a pretty avid user, and only very slowly realized that I'd begun carrying around "The Audience" in my head, which judged what I did and how I looked at all times.

Becoming disenchanted with that mode of consciousness was a very long journey, I'm humbled to say. A key moment for me was realizing that if I was in the city where some "friend" or another lived, I wouldn't try to contact them.

That's not a real friend. I'm not being a real friend. In fact, everything in the whole domain is mislabled, and who wins? The company and it's advertisers. Value is leeched from real-life existence.

Glad to be gone from it -- unknown, away, without apparent value!

</comment></comment><comment><USER4> I don't know why people take FB so seriously. I use it to post funny anecdotes about my life, like funny shit my kids say, funny photos, etc. I don't post vacation photos, or enhance my own self-opinion. I have a "small" group of 300 Facebook friends, and I use it to keep in touch. If someone is posting fake or annoying posts on it, then I'll unfollow them. That's it.

I do get sucked into an hour or more of videos though, which is a habit I need to break. Especially Graham Norton videos, I've never seen his show but the clips are always extremely entertaining.

</comment><comment><USER5> Quick note: Total number of people who use FB every single day of their lives in the US stayed steady Q1 to Q2 at 183 million people. This was through all the Cambridge and privacy stuff. The HN bubble is very different than reality.

<comment><USER6> It was growing exponentially.

<comment><USER5> US has been stable a long time (at least 6 quarters). International is still growing fast.

</comment></comment></comment><comment><USER7> Is the reason this is on the front page because he's an investor? Can HN not feature these "I am quitting facebook" every month? Let's get back to real news and real thoughts. Oh btw, I have quit facebook too because I was mentally unstable. AMA time but I bet no one would because I ain't Om.

<comment><USER8> > I have quit facebook too because I was mentally unstable.

I think this very effectively distills the essence of his blog post, too. His perception is that everyone is fronting. The fact of the matter is, not everyone is. Some people just post the highlights because they understand that the minutia is boring and not what people want to see. That he sees this as "fronting" is more a commentary on his own lack of self confidence. Well, that and the fact that he had to throw out how many followers he had.

<comment><USER9> I'm not sure I agree with this analysis.

I don't have a lack of self confidence and I consider the vast majority of Facebook posts to be fronting, even if the person actually posting is not actively aware of the fact that they are fronting. A lot of the time the awareness of "fronting" is absent, when it is in fact the main purpose driving the person to upload. Why else would people post very personal things about their lives to an audience they don't even want to reach out to on a regular basis? Even when they are in the same city, etc? Because those are not friends, and if they are not friends, the uploader is an actor presenting their daily demo real.

Of course there are exceptions to this, but I don't think that saying that a vast majority of people on Facebook are fronting is a reflection on our own personal lack of confidence, as much as it is barely a generalization.

</comment></comment></comment><comment> shady-lady Deleting facebook & twitter and de-gamifying as many other websites as I can (via tampermonkey scripts) is great.

reddit (my) karma score, & poster usernames -> hidden

HN (my) karma score -> hidden

slimming down everything to just content without any influencing factors(poster name, comment points) gives me a much better experience.

i find web forums which i frequent are so much better without karma & reactions.

</comment><comment><USER10> )

</comment><comment><USER11> I don't share most of the concerns people have about Facebook (including Om's here about sharing inauthentic life through photos)--I mostly just post text updates--but I wonder if their efforts over the last few years to move from people sharing political links etc to engaging more on original text posts have been working. I feel like when I posted stuff to FB some years ago I got more responses than when I post now.

Seems like the main activity that people I know are into on FB is Groups, which again takes it away from personal update territory. Good thing they bought Instagram/WhatsApp or they could have ended up in a decline phase already...

</comment><comment><USER12> "My excuse for not lecturing against the use of tobacco is, that I never chewed it; that is a penalty which reformed tobacco chewers have to pay; though there are things enough I have chewed, which I could lecture against. If you should ever be betrayed into any of these philanthropies, do not let your left hand know what your right hand does, for it is not worth knowing.

-Henry David Thoreau

(Never had Facebook account because it seemed something I didn't want all along. Was a "wacky" opinion for a long time and is now amusing to see all the noise).

</comment><comment><USER13> What I've done is deleted a majority of the amount of content I had on FB previously. I went back and deleted most of the content I had posted, and kept only a handful of posts. I still use FB for some groups that are only on FB and use Messenger for contacting some friends, so I can't really delete the account completely. But I've tried to clean out my account as much as possible.

I plan to do the same with Twitter as well. If anyone has links to good tools that can enable me to delete old Twitter content, please share!

<comment><USER14> I forget whether it was Twitter or Instagram but one of them, maybe both, make it incredibly difficult to bleach or eject from the platform.

20 per day deletion/unfollow limits, etc.

</comment></comment><comment><USER15> I think he really boils it down to the fundamental question everyone should be asking themselves: do you want to define yourself through the eyes of others, or not?

<comment><USER9> You need more upvotes

</comment></comment><comment><USER16> I'm not sure what to take away from posts like this. On the one hand, I have only a few hundred friends (and practically no followers) that I would be walking away from. On the other hand, I don't have a well-read blog and twitter following to fall back on.

So is it harder or easier for a nobody like me to quit Facebook? And is the main point of this post to migrate FB followers to Twitter followers?

<comment><USER9> Why is there even a need to fall back onto something? Migrating to another platform he considered less fronting and superficial was his choice, but I don't see the need nor appeal in that, personally.

</comment></comment><comment><USER17> I am like 90% sure Facebook still keeps track of you indirectly. So as far as Facebook is concerned, you definitely still exist after quitting.

[https://spideroak.com/articles/facebook-shadow-profiles-a- pr...](https://spideroak.com/articles/facebook-shadow-profiles-a-profile-of- you-that-you-never-created/)

<comment><USER18> Ghostery. Privacy Badger. To name two.

<comment><USER17> Do you believe tracking in websites is the only mechanism by which they collect information about you? Hint: it is not. At all.

</comment></comment></comment><comment><USER19> These days I use FB to follow events and participate in groups whose topic interests me. There is no other platform that comes close in terms of variety or critical mass for this.

</comment><comment><USER20> The sad truth is most people's friends are boring

<comment><USER21> There's nothing sad about being boring.

<comment><USER22> _May you live in exciting times._

</comment></comment></comment><comment><USER23> What is your "circle of happiness?"

</comment><comment><USER24> >I'm quitting fb for real this time.

>Oh, and look at all these thousands devoted followers I'm walking away from

>I just don't want to always put up a front of my existence for others to see

>I don't want to live for how others perceive me.

>Better share this transcendental experience on my blog.

k.

<comment><USER25> People often complain about being downvoted but your post actually adds nothing to the discussion. In fact, you just reframed everything Om said negatively.

<comment><USER26> What he's paraphrasing is "I have had a revelation about Facebook being bad, I'm better without it and you will be too. Rather than sharing this on Facebook where I'll reach hundreds of thousands of people that are using Facebook and might be helped, I'm sharing it on my blog where few will see it."

</comment></comment></comment><comment><USER27> Coming to YC Winter Batch 2019 - Squeezr, an on-demand masseuse app. For when you pull a muscle while patting yourself on the back for quitting Facebook.

</comment><comment><USER28> How do you spot that someone has quit Facebook? They'll tell you.

<comment><USER29> Well there's "quitting" and "stop using". I have friends who've quit and told me, etc. I also have friends who just went dark. I don't have updated non-FB contact info, because all our comms had collapsed onto FB - or were only ever FB. Their last post was in 2015 or 2016, and they obviously don't reply to Messenger. They just stopped participating one day.

</comment></comment><comment><USER30> Should I know who this guy is?

<comment><USER31> Maybe not, but please don't post unsubstantive comments here.</comment></comment>


MIT OCW: How and Why Machines Work (Spring 2002) - <AUTHOR> http://ocw.mit.edu/OcwWeb/Mechanical-Engineering/2-000How-and-Why-Machines-WorkSpring2002/CourseHome/index.htm

<comment><USER2> i'm delighted to see that solidworks (cheap) was used while other unis were still using pro-e/i-deas/catias (expensive)

maybe it's a stretch to say that schools which use cheaper, alternative resource tend to be of better quality compared to those which use more expensive, 'proven/best practice' resource</comment>


Report of working 3D printed gun - <AUTHOR> http://boingboing.net/2012/07/28/report-of-working-3d-printed-g.html

<comment><USER2> There was a small discussion about this here on HN previously where someone was effectively calling people terrorists for downloading these files.

Ill have to go back and look for the conversation, but we knew this was coming very soon after these files were built.</comment>