Filter all ICMP and watch the world burn - <AUTHOR> https://rachelbythebay.com/w/2015/05/15/pmtud/ <comment><USER2> For those who are new to this issue: ICMP is the sort of 'signalling' protocol related to IP itself. ICMP provides a few services (eg. classic ping), but critically when issues within the IP layer occur elsewhere on the internet while attempting the delivery of a packet, ICMP messages are usually sent in response. However, recently (~last 15-20 years) badly configured firewalls block all ICMP or certain types of ICMP, which can result in difficulties in communication. In this case, type 3 code 4 was blocked. More info @ [http://en.wikipedia.org/wiki/Internet_Control_Message_Protoc...](http://en.wikipedia.org/wiki/Internet_Control_Message_Protocol)

<comment><USER3> Thanks. Why does the source host sets the Don't Fragment flag?

<comment><USER2> According to the original IPv4 RFC @ [http://tools.ietf.org/html/rfc791](http://tools.ietf.org/html/rfc791) page #25...

 _If the Don 't Fragment flag (DF) bit is set, then internet fragmentation of this datagram is NOT permitted, although it may be discarded. This can be used to prohibit fragmentation in cases where the receiving host does not have sufficient resources to reassemble internet fragments.

One example of use of the Don't Fragment feature is to down line load a small host. A small host could have a boot strap program that accepts a datagram stores it in memory and then executes it._

What it seems to mean is things like PXE[1] or BOOTP[2].

Basically, DF was built to allow the sender to optionally force zero fragmentation by intermediate hosts en-route that are connected to networks with a smaller MTU than the packet size originally emitted by the sender. This was _originally_ intended to be of use because the sender was somehow made aware of limitations in the recipient's network stack.

 _Probably_ 20 or more years ago it was used for awhile as a latency-related hack for certain applications (VOIP, video, low-latency finance, certain scientific experiments generating vast amounts of data, etc.) mostly on UDP[3], though we have better methods for those now that operate through other IP headers (QoS).

Theoretically, intermediate nodes could also use it as part of path selection during routing, though I have no idea if this has been done or is encouraged - eg. a packet from node A reaches node B en-route to node C. Node B has two routes to node C. The lower-cost route is available with a smaller MTU than the packet size, and a higher-cost route is available with a large enough MTU to accommodate the packet size. The DF flag could be used by routing logic at node B to automatically shuffle the packet across that higher-cost route.

I believe the _Path MTU discovery_ [4] feature of modern Linux kernels also probably uses this mechanism combined with short TTLs (ie. maximum hop counts, which also cause ICMP errors to be returned on their failure, and are the basis of _traceroute_ [5], itself an unintended hack based on unrecognized capabilities of the IP protocol's specification) to optimize long-lived traffic flows.

There must be other edge-case or optimization-related wishy-washy reasons to set it, too. The main thing to remember is: none of these were really intended by the authors of IPv4. This whole historic pile of what-if edge-case hackyness has been thrown out in favor of a better system in IPv6[6].

[1] [http://en.wikipedia.org/wiki/Preboot_Execution_Environment](http://en.wikipedia.org/wiki/Preboot_Execution_Environment)

[2] [http://en.wikipedia.org/wiki/Bootstrap_Protocol](http://en.wikipedia.org/wiki/Bootstrap_Protocol)

[3] [http://en.wikipedia.org/wiki/User_Datagram_Protocol](http://en.wikipedia.org/wiki/User_Datagram_Protocol)

[4] [http://en.wikipedia.org/wiki/Path_MTU_Discovery](http://en.wikipedia.org/wiki/Path_MTU_Discovery)

[5] [http://en.wikipedia.org/wiki/Traceroute](http://en.wikipedia.org/wiki/Traceroute)

[6] [http://en.wikipedia.org/wiki/IPv6#Simplified_processing_by_r...](http://en.wikipedia.org/wiki/IPv6#Simplified_processing_by_routers)

<comment><USER4> The reason is because you never want routers to have to fragment your packets ever. Fragmentation is really inefficient. So any modern stack will always set DF and listen for ICMP unreachables. In other words, PMTU discovery.

None of the other reasons you mention are really relevant.

<comment><USER3> So, the sender uses DonfFragment as a tool to detect the optimal packet size.

Alternative idea: when router needs to fragment a packet, router passes the fragmented packet through, but sends an ICMP to the source - "fragmentation happened". (Or the party which re-assembles the fragmented packet, maybe receiver, sends this "fragmentation happened" message).

So this IP packet does not need to be resent, the source can optimize packet size for future, and the network doesn't break if ICMP is disabled somewhere.

We don't want to constantly send these "fragmentation happened" ICMP messages (if they don't reach the source and it keeps sending large packets), so the router sends ICMP not always, but only for first 3 fragmented packets of that source in each 10 minutes.

[I am just thinking, it's not a real proposal.]

</comment></comment></comment></comment></comment><comment><USER5> Unfortunately almost every time I've dealt with PCI-DSS compliance auditors they almost always raise the fact that I haven't got ICMP completely filtered.

It's always an annoying, long argument with them about why ICMP exists, why it shouldn't be completely filtered, and what the potential side effects of filtering it are.

<comment><USER6> Not PCI-DSS, but I dealt with security auditors for a client that insisted that we shouldn't allow ping... To the address of the public website... Because we might reveal there was something there.

My passive aggressive response was to point out, while copying the client, that a number of more prominent security auditors sites responded to ping, as well as the websites of any number of intelligence organizations, banks and similar.

<comment><USER7> Just had an audit with one of the biggest telcos, done by a large "security" firm. They insisted that the public website not respond unless the right Host header was there. Stupid, but OK, I can see it on a checklist for intranet apps.

But the real kicker: The site was TLS only, so connecting to the IP will still leak the hostname, from the cert.

Edit: This was a really big security firm, too. Totally worthless audit. They actually complained that a site admin could "include iframes in the HTML, which could be a malware vector" when uploading content. Ignoring that they could also upload scripts and arbitrary binaries.

After their weeklong "penetration test" concluded, I found some serious XSS (public user->admin, which could easily turn into system takeover) with about 5 minutes of looking. Are most audits this useless?

<comment><USER8> _After their weeklong "penetration test" concluded, I found some serious XSS (public user->admin, which could easily turn into system takeover) with about 5 minutes of looking. Are most audits this useless?_

Hiya! I started at Matasano/NCC back in February. Part of the reason I joined was to find out whether or not everything tptacek has been saying for years is true. Turns out it's pretty much all true. Some of that is awesome, like the hiring process. Some of that is scary, like the fact that someone of moderate skill level can usually break into most production apps.

My experience is limited. That said, put me on an audit and the first thing I'll check for is XSS and SQLi. The second thing I'll check for is authz: log into an admin account, note a URL to perform an admin action, log in as a normal user, try to access that URL. Third thing I'll check for is if there are any upload forms, because that's a common way to get RCE: upload a file and try to trick the app into executing it. Etc. Stuff that matters.

It's a point of pride to ensure that our assigned app has been pentested thoroughly by the conclusion of an audit. A thorough pentest doesn't necessarily mean finding every possible vulnerability, because time is often limited, but it does mean finding the serious ones.

If we include any findings in the final report which could be called "trivial" (there are occasionally some), they're marked as informational findings, i.e. their severity level is less than low. The reason we include them is because even though the finding doesn't necessarily pose any security risk, a client will often get another pentest from another security firm and diff the results. If the other firm points out something we thought was too trivial to include, the client will rightfully ask why we didn't find it. (We try to be pretty clear in the report about each finding, though, so you're not going to come away with the impression that we're saying you need to address something trivial.)

I don't know enough about your experience with that security firm you worked with to comment directly, but communication is one of the most important aspects of the job. If we find some flaws but don't communicate well to the client, then nobody was served by the audit. So if you're feeling like the whole process was a waste of time, you might want to shop around. There are several good security firms, not just Matasano/NCC, so you may want to give it another shot.

For what it's worth, the fact that you had a bad experience with one of the firms is actually painful to me. It's only recently that people started to care about security in a significant way, and it's a tenuous position. The more people who get a "security audit" and end up feeling like it was a waste of time, the more likely we are to end up back in a situation where people know there are probably serious security problems but feel like there's nothing they can do to find or fix them. There is: Give us a test environment and two weeks. We'll find what matters, and we'll give you a report explaining each issue and how to fix them.

<comment><USER9> Thank you for your comment! I want to add to it as a former pentester: it's absolutely painful to read about these nitpicky "the world is going to burn if you don't modify trivial security setting X that will destroy user experience". Not because these shouldn't be included in the report, but because the focus is wrong.

As strayptr, I would also include the trivial issues as "informationals" in the report as you do want your clients to know about these for a number of reasons. However, most of my time would go to hunting for severe issues, where I defined severe on some mental ranking based on "difficulty to exploit", potential impact,... In addition, these issues were also where most of my attention went to afterwards, because you need to explain and educate development, testing and business on the issues, why you think they are important and how to best/quickest fix them.

In my opinion, building up relationships and having empathy for your client is very important. I would always try to have a chat with development/test/business to get a feel of where their heads were at. That would help me both while testing (what is important to them? how did they develop it? what is their maturity?) and while reporting issues (they would actually believe me, I could help them rank the issues and they would allow me to brainstorm how to best mitigate the issues for their environment).

</comment></comment></comment></comment></comment><comment><USER10> We got hit massively by this at CloudFlare (though we were not explicitly filtering ICMP, but changes we made to our infra meant that PMTU packets got lost) We wrote a blog post about this too: [https://blog.cloudflare.com/path- mtu-discovery-in-practice/](https://blog.cloudflare.com/path-mtu-discovery-in- practice/) and the solution to our change: [https://github.com/cloudflare/pmtud](https://github.com/cloudflare/pmtud)

<comment><USER11> Interesting!

I'd think, in theory the ECMP router could keep track of the MTU on a per IP basis (rather than per TCP connection) based on it having received the ICM unreachable packet. And from that moment on, sending a spoofed ICMP packet back whenever one of the servers it's routing for sends a packet the router knows won't reach the host.

But even if that works, I'm by no means a network engineer, your solution of simply broadcasting the packets is probably more efficient in the real world.

</comment></comment><comment><USER12> icmp in ipv6 does much more than its ipv4 counterpart and most importantly:

1) L2 address resolution (neighbor discovery), which ARP used to do in ipv4,

2) full network autoconfiguration (global scope addresses, default route(s), DNS resolver), which DHCP used to do in ipv4 (although DHCPv6 is still an option),

3) multicast group management (MLD), which igmp used to do in ipv4,

4) path mtu discovery (through 'packet too big' messages this article references). Routers fragment packets exceeding the link MTU in ipv4, they notify the source of the lower mtu in ipv6.

ping, TTL exceeded, destination (host, route or port) unreachable and parameter problem were mostly carried over from ipv4.

Blocking 1, 2 (and to some extent 3) on a local network will most likely break ipv6 connectivity entirely while blocking the others will only break it in subtle, hard to debug ways (especially with ECMP and traffic engineering where multiple routes for a given destination can be used).

I've found that explaining this before asking network admins to unblock icmpv6 filters is a good way to succeed (although it can be hard, i'll give you that).

People aren't used to filter ARP or link local broadcast in ipv4 (which DHCP uses), so telling them that they need to allow icmpv6 to let stations merely _configure_ themselves is a bit of a mentality change.

At the same time, developers of firewall management tools like ufw understood this problem a while ago and insert a working, good, tried and tested icmpv6 accept list as first rule which you can't mess with.

Telling people to use ufw is usually much better than teaching them ip[6]tables.

<comment><USER13> We use a load balancer product that is Linux-based. It defaulted to blocking all IPv6 ICMP, including neighbor discovery. This made IPv6 not work at all. It was a struggle to get them to fix it. And I don't think they've released the update with the fix yet either.

</comment></comment><comment><USER14> Last time I checked, EC2 defaulted to filtering ICMP packets, with the predictable bad results:

[http://www.daemonology.net/blog/2012-11-28-broken- EC2-firewa...](http://www.daemonology.net/blog/2012-11-28-broken- EC2-firewall.html)

<comment><USER15> As a bonus, you can't enable them for things like ELBs where you don't control the box.

<comment><USER16> You can in VPC just fine. The ELB has a regular security group.

</comment></comment></comment><comment><USER17> When people filter ICMP is really really annoys me. Sure I get that some people don't like to respond to pings, or that you can ddos some routers by flooding them with 64 byte packets (old routers btw) but hey ICMP is a critical part of making the network work correctly.

</comment><comment><USER18> Discovering Path MTU black holes on the Internet using RIPE Atlas: [https://www.os3.nl/_media/2011-2012/courses/rp2/p57_report.p...](https://www.os3.nl/_media/2011-2012/courses/rp2/p57_report.pdf)

A Master thesis research report from 2012 which examined this very problem on a global scale, using the RIPE Atlas monitoring network.

</comment><comment><USER19> Eh, seen this so many times...

My favorite related problem was about 12 years ago when I had a Mac and a Linux box side-by-side and the Mac could connect to a Verizon site (a paging gateway) while the Linux box never even got a response to its SYN. I eventually figured out the Linux box had ECN enabled. Probably an out-of-date firewall at Verizon's end didn't like such exotic TCP options. Disabling ECN on the Linux box fixed the issue.

(I believe I was working on an email-to-page script at the time.)

<comment><USER20> ECN was a bit of a special case, and a major pain in the ass: it uses a previously-unused bit in the header and "security conscious" network hardware developers forgot the "liberal in what you accept", set-it-to-zero-when-you- create-a-packet-and-ignore-it-otherwise proper default behavior for unused bits.

</comment></comment><comment><USER21> Yup, I've had this: "ICMP is a security hole" lets turn it off.

such a tedious conversation to have with the networks(!) team

<comment><USER22> Can you explain how ICMP is insecure? Is it just ping being exploited?

<comment><USER23> ICMP can be used to affect routing on insecurely configured hosts. That might be an exploit vector? Circa 1995-97 there was the ping of death....but that was 20 years ago.

Most of these security best practices are like building code. They get written down and are never updated. For example, showers need a 2" drain pipe but tubs only need 1.5". The theory was that a backed up drain would flood a bathroom with a lower shower rim very quickly. It would take much longer with a tub (higher side wall). No one ever bothered to update the regulations once we stopped allowing 5 gpm showerheads. There's no reason put into it. Just "nope it says 2" required b/c we've always required 2"." "Why?" "Because that's how it is."

Same way with computer security.

<comment><USER24> "Code is not prescription."

</comment></comment></comment></comment><comment><USER25> When a client tries to send packets too big for the network (as when the client is configured with jumbo frames but the network isn't), this can be really painful to debug. The worst is that many things will work because small packets get through. For example, an "scp" connection may successfully connect, and then just hang when it starts transferring real data.

</comment><comment><USER26> This is a well known problem. Windows (since at least 2000) can detect this scenario and mitigate it [1].

[1] [https://technet.microsoft.com/en- us/library/cc960465.aspx](https://technet.microsoft.com/en- us/library/cc960465.aspx)

</comment><comment><USER23> I'd probably be saying "Eureka!" if this were 1997. But it's 2015. This is super basic stuff. Do people these days just blindly assume a MSS of 1460 is going to work on the Internet? Or do they think that the Internet is comprised entirely of Ethernet links?

Or has the use of cloud providers and reliance on higher level programming languages produced a generation of ops people who don't understand the mechanics of how things work?

<comment><USER23> Everyone who downvoted my comment needs to pick up and read a copy of Comer's "Internetworking with TCP/IP". That and Stevens' TCP/IP Illustrated are the best sources for networking out there. You won't find the info on any blog. It won't be in something on ServerFault or StackOverflow and definitely not HN. Buy, read, learn.

Yes, I know the US publisher has messed with the pricing for current versions but you can find the previous ones used pretty cheap. Other than dropping the IPng chapter, I doubt much has changed.

</comment></comment><comment> X-Istence The lowest MTU on IPv6 is 1280, which means that even if we go with the minimal MTU just to get traffic to flow, it's not as terrible as IPv4's minimum MTU: 576.

<comment><USER27> That just means you'll have to encapsulate ipv6 in ipv4 to get across those really poorly configured routers...

<comment><USER28> Would those routers support 6 in the first place?

<comment><USER29> If it's encapsulated it doesn't matter :)

</comment></comment></comment></comment><comment><USER30> Brings back memories from my past... [http://znep.com/~marcs/mtu/](http://znep.com/~marcs/mtu/)

Woefully out of date and wrong, but helped some folks out.

</comment><comment><USER31> We have what I think is a long running MTU problem on Rackspace hosting for a customer. We are losing parts of HTTP requests between the H5 load balancer and the customer's web servers (which are running IIS).

The header of the request reaches IIS and then the content body of the request fails to turn up causing a 500 error on the server.

Issue is mostly seen on POST requests where the content of the request is going to be split over more packets. It's been driving us nuts.

I wonder if we should also check the ICMP blocking too?

<comment><USER29> Hey! Ex-Racker (NetSec) here. The truth is on the wire, get captures and check where the packets are dropped.

Do you have the F5 in front of the webservers or on a different interface in one-arm mode? Second case you're going through the firewall, so I guess that's your scenario.

</comment></comment><comment><USER32> > ipv6

> someone blackholed the very important packets which say "fragmentation > needed but DF set"

IIRC IPv6 never fragments and uses MTU path discovery (via ICMPv6)

<comment><USER33> IPv6 does have fragments. Routers will not do the fragmentation. They just drop the packet and force the client to do it. It can be horrible if you're using a tunnel broker and don't lower your MTU.

</comment></comment><comment><USER34> Heh, back when google was just a white page with a search bar I noticed that the front page would come up, but he results didn't. Turns out I was on a home network connection with PPPoE which slightly decreases the maximum MTU.

I opened a ticket with google and a SRE called me back (to my surprise) and we tracked it down. Google had a new firewall that was blocking MTU negotiation.

</comment><comment><USER35> Educational Stack Overflow from the Google results for 'mtu':

[http://serverfault.com/questions/43866/whats-the-best-mtu- se...](http://serverfault.com/questions/43866/whats-the-best-mtu-setting-for- a-web-server)

</comment><comment><USER36> Damn, I had this issue a while ago but I was not able to figure out the cause. I posted to stackoverflow but nobody pointed me in this direction. now I went back and answered my own question :) thanks! @jonchang

</comment><comment><USER37> Some application protocols require ICMP _and_ another TCP or UDP port and won't send their TCP or UDP packets until the ICMP ping packet has successfully been responded to.

</comment><comment><USER38> Its really kind of depressing that this is 'news' enough that it gets 245+ upvotes here. It can't be older than the internet itself, obviously, but its damn close...

</comment><comment><USER33> Read the title and immediately knew it would be PMTU.

<comment><USER39> Ditto. Yet I still have this conversation with self styled "network architects" who want to blanket block all ICMP. It's depressing.</comment></comment>


Boeing-Backed Startup Lands JetSuite for Electric Plane's Debut - <AUTHOR> https://www.bloomberg.com/news/articles/2018-05-21/boeing-backed-startup-targets-2022-debut-for-electric-plane <comment><USER2> Interesting. Obviously this is challenging from a power and energy density point of view but I suspect the play is likely to be in being able to land planes at airports very close in to major cities where noise and pollution constraints dominate. If you have a plane that you're allowed to land 300 times a year at midnight at a field where you'd only be allowed to land at 50 times a year before 10pm with a conventionally powered plane you might be able to stake out a commercially viable niche.

<comment><USER3> The amount of air you need to move to create the thrust is not silent at all. Whether it is all electric or gas turbine it's going to be noisy.

<comment><USER4> Its like how about somewhere around 30 mph cars make more noise from going through the air than their engines.

<comment><USER5> Tyre noise sounds like the more likely source of car noise, at least that's how I previously heard this statement being made.

</comment></comment></comment></comment><comment><USER6> One application for super capacitors that I always think about is electric planes. These small planes represent a drop in the total fuel consumption of air travel. The majority of it is consumed by commercial passenger airlines and shipping.

The second most important metric batteries have to meet is charging time. The lower the time the plane spends on the ground, the better return on investment. Having to wait for a plane to charge is not ideal for airlines. A super capacitor power bank can be charged much faster than a lithium ion battery bank.

The third is power delivery. I haven't calculated the power required to take off, but given the usual 30s "sprint" (not sure what the technical term is here) to take off the rest can be calculated from that. I haven't calculated it yet, but lithium battery packs usually are restricted to Capacity == Power i.e. 1Wh == 1W. With super capacitors that ratio is sometimes 100x that

The downside to super capacitors is even the best ones created so far (in research not commercial) are the graphene ones that loose their power in 12h.

This isn't a deal breaker but it does probably limit a capacitor powered electric plane to 6hour rides max

Hope someone else finds this rambling interesting :)

<comment><USER7> I can imagine a hybrid where a super capacitor is used as a booster at takeoff, when power consumption is 5-10 times higher than in horizontal flight. It does not need to keep the charge for a long time, and can be charged right before the flight. It will eliminate many thermal issues with lithium cells at high currents.

<comment><USER6> That would be a good solution for the power delivery problem but not the charging problem

</comment></comment></comment><comment><USER8> It seems that electric plane will have one big pain point in adoption for larger passenger craft: the time to refuel/recharge the batteries. Gate dwell time is one of the major costs for an airline both in terms of lost revenue and in fees charged by the airport itself.

<comment><USER9> Possibly stupid question: Would battery swaps be a reasonable solution to this?

<comment><AUTHOR> These planes are hybrids - they use a turbine to charge batteries and power the EDF engines. I suppose the batteries are used for take off and cruise flight is mostly powered by the turbine (that doesn't have to be powerful enough for takeoff). Landing, again, can be purely electric.

</comment></comment></comment><comment><USER10> Given the title I thought they literally "landed" an electric plane, which would be quite nice for a startup. Turns out I was baited into clicking.

> Boeing Co.-backed startup Zunum Aero plans to deliver its first hybrid- > electric plane in 2022 to JetSuite Inc

</comment><comment><USER11> The next century of personal transportation will be autonomous electric cars for short distances, autonomous regional rail for medium within-density transport ( _e.g.._ interborough or within-the-Bay-Area distances), autonomous electric aircraft for cross-density transport( _e.g._ New York to the Hamptons or Cupertino to Napa) and cheap windowless airplanes for long distance. The unique aspect of this vision is the reduced role for public transit outside intracity subway and regional commuter rail. Autonomous cars and planes seem to increase road efficiency in a manner that competes effectively with rail for density-crossing transport.

<comment><USER12> whats great about windowless airplanes?

<comment><USER11> > _whats great about windowless airplanes?_

Blended-wing bodies [1] are very efficient. So you get a bigger jet that's cheaper to fly. Downside: some seats will be on the inside. Moreover, windows are a huge stress point on air frames. A windowless craft is cheaper to maintain.

If there's one preference travelers show, it's that for cheaper tickets. A windowless blended-wing aircraft delivers on that.

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

<comment><USER13> One of the biggest issues with further adoption of Blended Wind Body aircraft is that current FAA regs require demonstration that deplaning the aircraft in an emergency is possible at full seating capacity, including crewmembers, in 90 seconds or less [1], although studies and simulations have been done that continue to evaluate this [2]

BWB with their pax on the inside, make this very challenging.

[1] s7: [http://fsims.faa.gov/WDocs/8300.10%20Airworthiness%20Insp%20...](http://fsims.faa.gov/WDocs/8300.10%20Airworthiness%20Insp%20Handbk/Volume%202/2_077_00.htm)

[2] [https://fseg.gre.ac.uk/fire/fseg_ped2010_bwb_paper_distrib_f...](https://fseg.gre.ac.uk/fire/fseg_ped2010_bwb_paper_distrib_final.pdf)

</comment></comment></comment></comment><comment><USER14> Time on the ground = time not being spent on hauling paying passengers.

This is the key problem with battery-powered electric vehicles and why fuel cells make so much more sense that battery packs. Fuel cells are a much "harder" technology to get correct and the tech is very difficult to get correct.

<comment><AUTHOR> This is why this plane uses a turbine to power the two EDF engines, supplemented by the batteries it charges during cruise flight.</comment></comment>


Boom Professional Social Network LinkedIn Passes 100 Million Members - <AUTHOR> http://techcrunch.com/2011/03/22/boom-professional-social-network-linkedin-passes-100-million-members/ <comment><USER2> "To be exact, the U.S. has 44 million LinkedIn members, and there are 56 million members outside of the U.S. Brazil is seeing the highest growth rate, with new user adoption rising 428 percent year-over-year. Mexico is also seeing major growth, with membership growing by 178 percent year-over-year."

Fascinating. I had no idea of the global reach.</comment>


Why MacRuby Matters - <AUTHOR> http://www.slideshare.net/importantshock/why-macruby-matters

<comment><USER2> I was unaware of the ahead of time compilation stuff, anyone got a more expansive link on that topic?

edit, found one: [http://lists.macosforge.org/pipermail/macruby- devel/2009-Jul...](http://lists.macosforge.org/pipermail/macruby- devel/2009-July/002062.html)

Off-topic: anyone else sick of slideshare? Why exactly do they need flash to show a series of images (most of which have images of text)?

<comment><USER3> I would recommend downloading the .key (Keynote) file from Slideshare and viewing it on your own, if possible. The slide notes are useful, more of the presenter's ideas shared (via <http://twitter.com/importantshock/status/4430454006>).

I initially thought that was the reason why it was in flash; so slide notes would be visible somehow. Thats not the case though.

<comment><USER4> The notes are visible on slideshare. Click on the "Notes on slide X" tab.

<comment><USER3> Didn't see that, thanks for pointing it out.

</comment></comment></comment></comment><comment><USER5> The main issue I have with anything that's not Objective-C is the lack of documentation. For example, how do I know I can do things like this (from slide 76) without having to deal with an entirely new set of documentation?

gradient(:start => (:name => "grey"), :end => (:name => "blue))

While I do agree that Objective-C has many, many drawbacks, the fact that Cocoa was designed with ObjC in mind, makes me stick with it rather than trying to work Cocoa in another language.

<comment><USER6> The example you've given is of Hot Cocoa which is a series of nice wrappers around common Cocoa UI operations

The direct mapping from Obj-C to MacRuby is quite simple. Here's an example from some code I'm working on at the moment

      TPShot *newShot= [[TPShot alloc] initInWorld:world
                                        atPosition:shotPos
                                            facing:facingAngle];

becomes

      new_shot= TPShot.initInWorld world,
                        atPosition:shotPos,
                            facing:facingAngle

</comment></comment><comment><USER4> MacRuby is a pretty interesting project. I'm not a huge ruby fan, but it definitely does have some syntactic advantages over Objective-C.

Objective-J is walking a similar line, and thanks to its JavaScript base it has many of the same things MacRuby brings to the environment. MacRuby probably has better immediate performance potential, but Objective-J has more flexibility in future language design decisions.

It's a good time for those of us interested in Cocoa and its related projects.

</comment><comment><USER7> Just saw this at C4, good preso! I haven't learned ObjC yet, but I can grok Ruby.</comment>


Ask HN: Does your company get positive ROI from its ad spend? - <AUTHOR> Occasionally, I come across blog posts where people complain about one or more of:
1) High and rising CPC rates for major platforms;
2) Difficulty matching activity with ad clicks;
3) Platforms intentionally user over-generous attribution models, causing uncritical clients to overestimate their ad ROI, and to continuously spend money on unprofitable campaigns;
Some companies also have a different problem:
4) The people who deploy ad spend are paid on the performance (ROI) of that ad spend, but are also in charge of how that performance is measured. So they're incentivised to be as generous as possible in attributing activity (e.g. purchases) to ad campaigns.
Given all of the above, I'm curious to know whether you think your company suffers from these problems, and whether overall your ad spend is managed well and/or has positive ROI. <comment><USER2> We definitely did, there was an immediate, directly correlated increase in user signups while we ran ads, and an immediate corresponding drop when we stopped them. Looking over ~12 months of analytics and usage data in hindsight, Google Search ads were the primary drive in signups.

The users we got through ads were generally surprisingly high quality too, they stuck around and continued to play games for many months, even years after signing up, in an industry with relatively high churn (free online games).

<comment><USER3> But was the ROI positive ?

<comment><USER2> I mean it got us investment money, but we ended up pivoting away from the original business model before becoming profitable, so it's hard to say.

</comment></comment></comment><comment><USER4> Hey my agency creates profitable leads using Google and Facebook Ads.

We focus on high ticket industries like wealth management, real estate and legal services. We also sell a ton of info products.

Here to answer questions :) google analytics is your friend

</comment><comment><USER5> I worked in ecommerce for 10 years and got to know the quantitative marketing folks well. All marketing campaigns were tracked and analyzed weekly based on the concept of "marketing income". Marketing income at the order level was defined as: Marketing Income$ = Order Total$ - Cost of Goods$ - Shipping$ - Marketing Expense$.

<comment><USER6> This might be a dumb question, but how did they know that marketing expenses drove more orders (rather than just eating into their margins)?

<comment><USER2> Good data-driven marketing teams work hard to establish control groups and known baselines before starting high-spend campaigns, and the ROI of those can be quantified by referrer info if they're highly specific and keyword-related.

As for more general campaigns, in my experience, it's a crapshoot, if the numbers go up everyone is happy whether or not marketing was responsible for the majority of it. I'm sure other companies have better approaches than that though.</comment></comment></comment>


DirecTV may remove CBS - <AUTHOR> https://keepcbs.com <comment><USER2> I looked through the shows that I would "miss out on" without CBS, and not much of value would be lost. But there is always the CBS app where you can watch shows the next day without a cable provider and everything is available on the CW without a cable subscription.</comment>


Show HN: cta.js – Animate your 'action-to-effect' paths - <AUTHOR> http://kushagragour.in/lab/ctajs/

<comment><USER2> I tried this and found it to be incredibly poor.

Then I discovered by reading the comments that this is because it doesn't work correctly in my browser.

Normally, I would advise you to prominently display information about where it works... except that in today's world, not being cross-browser makes a library like this essentially useless. Instead, I would suggest not bothering to publicize this until you have it working in all major browsers.

<comment><AUTHOR> The library works in all major browsers now. Thanks for the feedback.

</comment></comment><comment><USER3> I like the effects but the fact it only works with Chrome is a no-go for me. I don't see it being be too difficult to get this working in safari, firefox or modern IE..

<comment><AUTHOR> That is the first thing on my priority list. Will be coming soon.

<comment><USER4> I'm curious, what is it that makes it Chrome only?

Looks like only CSS transition and animation is special cased for WebKit but that's been unprefixed in Firefox since years back.

[https://hacks.mozilla.org/2012/07/aurora-16-is- out/](https://hacks.mozilla.org/2012/07/aurora-16-is-out/)

Edit:

Seems like getComputedStyle is buggy in Firefox?

        « window.getComputedStyle($0).background
        » ""
        « window.getComputedStyle($0).backgroundColor
        » "rgb(74, 144, 226)"
        « window.getComputedStyle($0).backgroundImage
        » "none"

$0 is the currently inspected element, in this case: .js-modal-2

Edit2:

Possibly "works as intended"?:

> getPropertyCSSValue is required to return null for these, and we implement > getPropertyValue in terms of getPropertyCSSValue.

[https://bugzilla.mozilla.org/show_bug.cgi?id=889091](https://bugzilla.mozilla.org/show_bug.cgi?id=889091)

If so, the fix would be to use the actual attributes rather than the composite attribute.

<comment><AUTHOR> Fixed for firefox now. Using computed style's `backgroundColor` key.

<comment><USER4> Splendid! Nicely done. :-)

</comment></comment></comment></comment></comment><comment><USER5> This looks nice. It seems to have much of the same functionality as jquery coupled with jquery-ui, right? Or am I missing something? I've used jquery to do all sorts of slide animations and it's cross browser (which may help you with the Chrome only issue - if you decide to port as a jquery plugin).

I do really like the sidebar pop-out. I've never seen that in jquery before - or perhaps missed it in the docs. Good job.

</comment><comment><USER6> It seems a little ironic that the main call to action on the website ("Get Started") doesn't seem to use the library.

<comment><AUTHOR> I know, I was to implement a modal on the 'getting started' button. But in the end had to do without it for time reasons. But I would still like to have it soon.

</comment></comment><comment><USER7> > Carefully choreographed motion design can effectively guide the user's > attention and focus through multiple steps of a process or procedure, avoid > confusion when layouts change or elements are rearranged, and improve the > overall beauty of the experience.

I could not agree more!

</comment><comment><USER8> Great, yep that's what we need. I prefer to use animation only to guide the user - not for 'oooh-ahhh' Flash-esque nonsense. So a library geared towards just that would save so much time.

Well done - and thank you, looking forward to cross browser version!

</comment><comment><USER9> Chrome only makes it hard to use, but I've starred it and if I can somehow squeeze in time, I'd love to fork the project and see if I can help bring it to other browsers.

<comment><AUTHOR> Cross browser is on top of list. Would really appreciate any contribution.

<comment><AUTHOR> Latest Chrome, FF and Safari are now supported.</comment></comment></comment>


Stali - statically linked linux - <AUTHOR> http://sta.li/

<comment><USER2> Much of open source software source code sucks in linux. Things could have been leaner, smaller and written with cleaner source code. I haven't checked thoroughly but I am pretty sure I can find lots of places where code could be factored out or made smaller. This goes for glibc too, and no surprise certain statically linked binaries turn out to be simpler.

</comment><comment><AUTHOR> There are a couple of other ways to make the distro even smaller:

      * Use UPX to compress executables: http://upx.sourceforge.net
      * Use a compressed filesystem like squashfs, cramfs, or fusecompress

</comment><comment><USER3> Noble goals, and I'd probably run it, if it were available for download.</comment>


Seed funding for athletes: buy a share of this pitcher's future performance. - <AUTHOR> http://www.realsportsinvestments.com/Player_Profile.php

<comment><USER2> Question - how can they avoid SEC regulation and rules? Being a market is a difficult and expensive thing to do....

[edit] looked at the FAQ, however they don't actually state WHICH of the exemptions they fall under. I thought if you issued a security that had more than 20 non-qualified investors you needed to do reporting and file w/ the SEC.

</comment><comment><USER3> Looks like they sold out... if it was legit and available, I think it would be an incredible investment based on the MLB minimum salary of $390,000. Of course, there must be a reason this guy needed $50k.</comment>


Show HN: My First OSS Project, Classic Finder - <AUTHOR> https://classicmacfinder.com <comment><USER2> I think it's a fun project!

It's obviously early, but since you've posted it, I'm guessing you're looking for feedback?

The look is great, it's a fun way to browse the FS, and once this is further along I might use it.

It looks like the menu items (Label, etc) don't work yet?

If I close the main window (/) there doesn't seem to be a way to get it back - Even if I click the app in the dock, I need to re-launch the app.

It displays apps as directories. I get this, because of the way modern apps are packaged, but something you might want to consider.

As someone else points out, it's not resizable.

You can't seem to move the icons.

It doesn't seem to remember window position. This is a big one. Part of what made the classic Finder distinctive was that metaphorically a file browser, it WAS the files.

When you open a folder in a specific spot, it should remember that spot you put it, and open there again next time. This (combined with other tricks) helped it feel like the folder WAS the files, not just a window to finding them.

The icons should work this way as well - I might want to store all my work files on the left side of the folder - Every time I open that folder, it should display them on the left again, so I know which are which.

Keyboard shortcuts and mousewheel aren't setup yet.

It's a cool project! I hope you keep going with it.

If you haven't, I'd read John Siracusa's articles on ArsTechnica - He talked a lot about the classic MacOS Finder, and what made it interesting and special.

<comment><AUTHOR> Yes, I love the feedback!

This is a great list! I _completely_ forgot about the saved positioning of the windows.

I'm definitely going to keep working on this and fleshing it out. I'll be using your feedback as a guide! Thanks! :)

</comment></comment><comment><AUTHOR> I have been working on creating a replica of the classic MacOS Finder in Cocoa/Objective-C. After about two years of hacking and doodling, I have finally gotten it to a point where I think it's worth showing.

Hope you all like it!

</comment><comment><USER3> Great work ! I wonder if this will build on any of the libraries that let you use Objective C, X-platform - maybe on GNUStep ?

<comment><AUTHOR> Thanks! :)

I think that it would probably build mostly fine on GNUStep or Cocoatron. It's not dependent on any of the macOS UI controls - since all of them are drawn from scratch. And the APIs this is calling into... they've been around forever.

The file system operations themselves, well, they are mostly just NSTask's that hand off to the command-line programs in /bin with a few arg's attached to them. (I know, I could do some of these with NSFileManager and it'd be better, but I wanted to be consistent.)

The only hangups I can think of (for building cross platform) would be maybe some of the syntactic sugar and ARC.

</comment></comment><comment><USER4> Can't resize windows yet, but nice start! I look forward to cluttering up my monitor with intermediate folders leading to various leaves. :)

<comment><AUTHOR> Thanks! And yes, getting window resizing is on my list!

I have a new appreciation for how tricky it is to get even some of the most basic controls and their functions right. Basic scrolling and scrollbars felt like a hurculean achievement.

</comment></comment><comment> 52-6F-62 Haha this _is_ fun! I want more! I _guess_ I could find set up an emulator...

but seriously, good fun. Keep it up.

<comment><AUTHOR> More will be coming, and I won't stop until Classic Finder reaches parity with the original. Thanks for giving it a try! :)

</comment></comment><comment><USER5> Still on 10.11, sadly, but this project looks very neat.

<comment><AUTHOR> Ahh yes. There's nothing really groundbreaking in there (in terms of API usage), so I should probably be able to set the build to an earlier version. ... let me see! :)

</comment></comment><comment><USER6> sweeet</comment>


Let's Code: Test-Driven Javascript kickstarter ends today with over $36K - AMA - <AUTHOR>

My "Let's Code: Test-Driven Javascript" kickstarter [1] announced on HN three weeks ago [2] is wrapping up today. It's been far more successful than I anticipated, with over 800 backers and over $36K in pledges. I thought HN might be interested in my experiences, so I'll be answering questions in this thread.<p>[1] http://www.kickstarter.com/projects/188988365/lets-code-test-driven-javascript<p>[2] http://news.ycombinator.com/item?id=3977240 <comment><USER2> How familiar were you with KS? I can see you backed a recent project yourself. When did KS come on the radar for you?

<comment><AUTHOR> I play D&D and occasionally read Order of the Stick, so I first started paying attention when Rich Burlew had his record-breaking Kickstarter [1]. Rich's professionalism and good management of the process was an inspiration for how I've been approaching mine. It's actually been pretty interesting to follow along with his updates, even though I didn't back his project.

I'd heard about it before then and a friend of mine had also conducted a Kickstarter [2] but up to that point I had never looked at an actual project.

[1] [http://www.kickstarter.com/projects/599092525/the-order- of-t...](http://www.kickstarter.com/projects/599092525/the-order-of-the-stick- reprint-drive)

[2] [http://www.kickstarter.com/projects/242604490/irish- language...](http://www.kickstarter.com/projects/242604490/irish-language- hunt)</comment></comment>


Tesla reports great Q3 results, expects to be cash flow positive by Q4 - <AUTHOR> http://www.engadget.com/2012/11/05/tesla-q3-2012-earnings/ <comment><USER2> I don't understand why Tesla's losses keep increasing; now they're losing $33M a month, up from $20M a month a year ago and roughtly the same as last quarter. That with $50M in revenue this quarter and actual shipping product. Can someone explain? Are they still purchasing capital equipment? Are their overheads that high?

That said, $30M a month is not that many cars. If they can sell them, and losses don't increase as a function of sales, which seems to be the case now, they will eventually be in good shape.

EDIT: TL;DR: This quarter they lost the same amount as last quarter but sold 25 million more in cars. That means for every additional dollar in car they sold over last quarter, they lost that dollar. Not exactly scalable but hopefully temporary.

<comment><USER3> Right now they are building the Signature series cars. These are the first 1000 cars. The reservations for these cars involved a $40k payment up front, in some cases up to 3 years ago. General production cars only required a $5k payment up front. As a result, they are only capturing ~$50k per car, versus ~$85k once GP cars start rolling off the line.

In addition, they've been ramping up production (they're roughly halfway to their target 400/wk goal), and that involves overhead like training new staff and building out an operations team. They should get to full production capacity at the end of the month, but they've already hired those extra workers and they're going to burn through cash while they get up to speed.

<comment><USER4> > As a result, they are only capturing ~$50k per car, versus ~$85k once GP > cars start rolling off the line.

That is not how GAAP accounting works. You record revenue when you finish building the car and it leaves the factory gate, not when you accept a deposit.

<comment><USER5> They did say "cashflow" positive by Q4 though, cashflow is recorded when cash moves, not when revenue accrues.

</comment></comment></comment></comment><comment><USER6> Great news.

Its interesting how in some political ads I've been seeing, a politician is 'called out' for supporting funding for companies like Tesla specifically.

<comment><USER7> There's this idea floating around that governments shouldn't support businesses. I guess there is nuance in that some might say: government should support business sectors, but not specifics businesses over others.

Anyway it's an odd argument when we look at the history of the country where governments and specific companies often worked hand in hand and continue to do so in so many areas.

Many argue that the American government ought to be more aggressive about being pro-business, as our friends abroad are. E.g. if the Taiwanese, Israelis, Chinese, etc have very strong government-private partnerships (e.g. subsidies for engineering jobs, or green-lighting through regulatory processes, or access to cheap capital) then the US competitors have trouble competing. What I find so odd is the same camp that often says the US needs to be more pro-business, is often, as you describe, against government support of American business!

<comment><USER8> Just because other countries are corruptly sponsoring businesses to line the pockets of politicians doesn't mean we should be doing that in America. There needs to be an ideological line drawn that says we will _not_ pick winners in a market, and we will _not_ protect failing businesses. That means large and small companies get the same levels of "support" from the government, none. Once you stop doing that you end up with a fascist co-mingling of government and industry ( kinda like we have now )

<comment><USER9> Yes! We should do things based on ideology! Not results! Not empiricism! Instead: principles and handwaving.

Singapore proved that heavy government subsidization of research can pay enormous dividends in economic growth. Other countries are having tremendous success doing the same.

<comment><USER8> So what do you say when the government doesn't decide to support your start up, but instead picks your competitor and runs you out of business because they happen to be related to a senator ? The ends don't always justify the means.

<comment><USER9> Leaving aside the silliness of deciding macroeconomic policy on hypothetical edge cases for a moment... How often does that happen? The US government is utterly paranoid about nepotism, to the extent that we waste a huge amount of money in the bidding process for government contracts because we don't want to seem as if we're favoring anyone, even if that favor is the result of something like having done good work in the past. It's an imagined problem.

<comment><USER8> This isn't an edge case. In fact the NYT just did an expose on how this effects China[1]. You will also find this kind of corruption in every other country where the government is allowed to openly partner in private ventures. Heck we did it in America with Boeing under the pretense of security and managed to mothball our entire aviation industry.

1\. [http://www.nytimes.com/2012/10/26/business/global/family- of-...](http://www.nytimes.com/2012/10/26/business/global/family-of-wen- jiabao-holds-a-hidden-fortune-in-china.html?hp&_r=0)

See Also: <http://en.wikipedia.org/wiki/Yukos>

<comment><USER9> It's an edge case in the US, and it's not like we don't have public/private partnerships here.

<comment><USER8> For now its an edge case. Thats partially the case because we put such stringent restrictions on the kinds of assistance we can offer, but even in America there are claims of corruption with giving out government assistance.

[http://www.politifact.com/florida/statements/2011/nov/15/ame...](http://www.politifact.com/florida/statements/2011/nov/15/americans- prosperity/solyndra-ad-president-barack-obama-taxpayer-money/)

</comment></comment></comment></comment></comment></comment></comment></comment></comment><comment><USER10> I loaded few hundred shares of TSLA in my portfolio only because I love the innovation this company has to offer. I would normally not invest in a company that has high uncertainty like Tesla but something about the company and Elon Musk made me own a piece of it. I am not sure if it was a good investment, but I am happy to be a part of it.

<comment><USER11> It's not often that us investing plebs can get in and bet on people like Musk fairly early on.

I did the same thing about a year ago and I'm still happy that I did, despite the stock not moving over the past year. I do believe Tesla can become a major car manufacturer during the transition to electric cars, since this period will likely be fatal to some of the weaker legacy companies.

I also realized that I may have purchased a ticket to Mars. If Musk's plans for both Tesla and SpaceX pan out, my Telsa shares will hopefully be worth as much as a trip to Mars in 30-35 years :)

<comment><USER10> I agree... and I'd be happy to see Tesla really bring innovation in automobile industry not just in electric car segment. But I also fear it being acquired by behemoths like GM or Toyota, that would just kill all the innovation.

</comment></comment></comment><comment><USER12> Hopefully their financials continue to be, if not strong, at least good enough to support the business. They seem to have good leadership and great ideas about how car transportation and the industry needs to change.

</comment><comment><USER13> Why's the stock going down so far today?

<comment><USER14> Well it was up almost 9% yesterday. Today's down is probably just a calming down of the large increase yesterday (but I don't know, I'm just making that up).

<comment><USER13> That seems to happen a lot to stocks after a large daily increase or decrease (it reverts somewhat the next day)

Has anyone investigated that as an investing strategy?

<comment><USER15> Hi,

I used to invest back in the day. Anyway, there are many investing strategies. They all have names such as Value, Growth, Event Driven, etc. I won't list them all. The investing strategy that attempts to exploit movements in stock price after an event (e.g. the type that you are asking about for the earnings announcement in the Tesla example) is called "Event Driven" investing. Another example of an "event" would be after an acquisition is announced to the public. Typically the target (one being acquired) stock will go up and the acquiror (one acquiring) will go down. Investors often try to take advantage of this trend. What is the relationship that investors are betting on if the target price always (usually) goes up, and the acquirer going down? Closing risk. At any point the acquisition, despite being publicly announced, could fall apart because of due diligence issues, etc.

Relating all that back to your question about Tesla: the fundamental value or true value of a company may or may not be reflected in a company's stock price. Think of the stock market as a manifestation of what people (investors) might believe the value is, but the reality is that the fundamentals might be vastly different. The reversion back to norm is something that happens as the market (investors who are imperfect--trust me--think AIG, Bear Stearns, Lehman) attempts to settle on true value.

Side note: Volatility in the stock price could also be attributed to a small float (not that many shares outstanding which leads to a small number of investors causing spikes in the price), but I'd have to look at Tesla's stock info to be certain.

Hope this helps,

Jenny</comment></comment></comment></comment>


Show HN: Slack2Peach, open-source Slack client for - <AUTHOR> http://slack2peach.cloudapp.net/ <comment><AUTHOR> hey guys, developer here. This is a third-party open source Slack client for peach. Built it over the weekend; was super fun! Its still very early and has only a few commands to start with.

Give it a try and let me know what you guys think!

Here is the discussion on Product Hunt (if you are interested).

[https://www.producthunt.com/tech/slack2peach#comment-222633](https://www.producthunt.com/tech/slack2peach#comment-222633)</comment>


How to Get Rich (without getting lucky) (2018) - happy-go-lucky https://mobile.twitter.com/naval/status/1002103360646823936 <comment><AUTHOR> PDF version at [https://drive.google.com/file/d/1eUVz5ToR2ZqdL2x3Y2sypNNdImr...](https://drive.google.com/file/d/1eUVz5ToR2ZqdL2x3Y2sypNNdImrlC26m/view)

</comment><comment><USER2> Very interesting... Following now :)</comment>


A personal story about flight predicitions - <AUTHOR> http://story.getflyr.com/post/104366555118/a-personal-story-about-flight-predictions

<comment><USER2> A suggestion: I think everyone's mental model for flight prices is that they go up as you get closer to the departure date.

I would therefore suggest in your marketing emphasizing cases where this wasn't the case i.e. where you add value.</comment>


Xilinx Virtex 7 FPGA bitstream has been reverse engineered - <AUTHOR> https://github.com/SymbiFlow/prjxray <comment><AUTHOR> For some context this is a very popular and cheap series of FPGA devices. For example you can buy the Arty board which has one of these FPGAs for $99 ([https://store.digilentinc.com/arty-a7-artix-7-fpga- developme...](https://store.digilentinc.com/arty-a7-artix-7-fpga-development- board-for-makers-and-hobbyists/)), or the slightly more advanced Nexys 4 DDR for $265 ([https://store.digilentinc.com/nexys-4-ddr-artix-7-fpga- train...](https://store.digilentinc.com/nexys-4-ddr-artix-7-fpga-trainer- board-recommended-for-ece-curriculum/)).

Currently you must use the Xilinx Vivado tool which is a 40 GB download [no, that isn't a typo], requires a paid license to unlock the full features, and is generally awful to use.

This work should eventually lead to a complete open source toolchain to program these devices, just like Project IceStore for the Lattice devices ([http://www.clifford.at/icestorm/](http://www.clifford.at/icestorm/) [https://rwmj.wordpress.com/2018/03/17/playing-with- picorv32-...](https://rwmj.wordpress.com/2018/03/17/playing-with-picorv32-on- the-ice40-hx8k-fpga-breakout-board-part-1/))</comment>


Top 50 Mac Terminal Commands - <AUTHOR> http://www.mactricksandtips.com/2008/02/top-50-terminal-commands.html

<comment><USER2> This one might be the greatest: telnet towel.blinkenlights.nl

Never more shall I be bored during the installation of Debian. Combined with the glamorous features of 0verkill (<http://artax.karlin.mff.cuni.cz/~brain/0verkill/>) I will soon be able to get completely rid of X11.

No more shall I be dependent on Nvidias buggy drivers. Buggy, woggy, woo!

<comment><USER3> That's quite possibly the greatest thing I've ever seen.</comment></comment>


Gitlab runs on Azure - <AUTHOR> https://www.reddit.com/r/linuxmasterrace/comments/8oxjno/for_all_the_people_who_left_github_and_migrated/?st=JI2OWDTJ&sh=e6f55f60 <comment><USER2> While this is true today, it will be changing very shortly. We are full steam ahead and heads down on our migration to Google Cloud Platform. You can follow along on our progress if you'd like at [https://gitlab.com/gitlab- com/migration](https://gitlab.com/gitlab-com/migration)

<comment><USER3> So Gitlab is switching from being hosted by a business focused company to an ad focused company?

Which basically means, that all the people who hated the buyin from Microsoft are becoming part of the Google ad data warehouse?

That's, uhm, reassuring to know...

<comment><USER4> If you've seen Windows 10 (ads and telemetry) it's probably only fair to say that MS is also highly interested in end-user data and ads, just like Google.

<comment><USER3> Yet, their business model doesn't rely on my data and ad-targeting me.

Besides, from my experience, every software vendor is of course interested in telemetry. Otherwise, I don't really know which features my customers are using, and on which I should focus more.

Maybe I'm biased here.

</comment></comment></comment></comment><comment><USER5> Using a company's service is not the same as being completely owned by them. Kind of a dumb little "gotcha!" to try and feel clever over. What? should we make sure a company we like isn't using Windows before using their services, too? or Office? Outlook?

<comment><USER6> If you check the history of README.md, you'll see that this process was initiated in December 2017 -- well before the GitHub acquisition announced this week.

</comment></comment><comment><USER7> I can see how this rubs people, but rationally, what difference would it realy make if they run on Google's or Amazon's infrastructure instead? Even 'own servers' would still be hosted in some major data center, connectivity served by the same corporate telcos.

</comment><comment><AUTHOR> Just ironic

<comment><USER8> No, this is: [https://wiki.openstack.org/wiki/Ironic](https://wiki.openstack.org/wiki/Ironic)</comment></comment>


China Slips in Its Rush to Embrace Electric Vehicles - <AUTHOR> https://www.wsj.com/articles/china-slips-in-its-rush-to-embrace-electric-vehicles-11569497436?mod=rsswn <comment><USER2> behind paywall</comment>


Russian Hackers Stole NSA Tools from Contractor Who Used Kaspersky Software - <AUTHOR> https://www.nbcnews.com/news/investigations/russian-hackers-stole-nsa-tools-contractor-who-used-kaspersky-software-n808101 <comment><AUTHOR> Why would he bring classified malware anywhere near an anti-virus? Isn't it the job of AV software to detect and report new cases of malware?</comment>


Minus Firefox and Chrome Extension - <AUTHOR> http://blog.minus.com/2011/10/05/minus-firefox-and-chrome-extension/

<comment><AUTHOR> Direct Chrome link: [https://chrome.google.com/webstore/detail/kgphklnbopgbelmcam...](https://chrome.google.com/webstore/detail/kgphklnbopgbelmcambccnaecijlnhno)

Direct Firefox link: [https://addons.mozilla.org/en-US/firefox/addon/minus- share-s...](https://addons.mozilla.org/en-US/firefox/addon/minus-share- simply/versions/)

</comment><comment><USER2> Thanks, good job on the FF plugin.

</comment><comment><USER3> awesome possum. definitely been waiting for the chrome extension.

</comment><comment><USER4> this is sweet! nicely done</comment>


The Free Music Archive is closing this month - <AUTHOR> https://www.theverge.com/2018/11/7/18073346/free-music-archive-closing-wfmu-creative-commons-cheyenne-hohman <comment><USER2> Before this article I had never heard of this website before. So sad to see a site like this go. Like the director of the site said, I'm glad archive.org will be able to provide a carbon copy, but this quote makes it seem bittersweet:

"If it just goes into archive.org, it's going to be there in perpetuity, but it's not going to be changing at all," Hohman says. "It's not going to be the same thing, that sort of community and project that it was for ... almost 10 years."

Here's to hoping someone with more capital than me can help keep this site afloat. I'm willing to donate what I can (read not a lot) if there is presented a greater chance of extending the service's lifetime. Considering the shutdown is already scheduled this month, I feel like my small donation would be too late unless there was a more transparent fundraiser.

</comment><comment><USER3> Such a bummer.. hopefully it gets picked up by a different company before it dies entirely</comment>


Richard Stallman defies push by 27 GNU Project developers to end his leadership - <AUTHOR> https://news.slashdot.org/story/19/10/12/0027247/richard-stallman-defies-push-by-27-gnu-project-developers-to-end-his-leadership <comment><USER2> I think even before this "scandal" Stallman's extreme ideology has only further alienated GNU. Stallman should have been out years ago.

<comment><USER3> I am just wondering if it is possible to link to the myriad calls for Stallman's resignation prior to the recent events?

I somehow missed all of them, but it seems every recent comment section on Stallman contains a great many people saying it was time for him to go anyway.

</comment></comment><comment><USER4> What has Stallman done that is so bad? I can't seem to find anything specific. Not asking to be controversial, but seeking to understand.

<comment><USER5> He resigned after these conversations blew up [https://www.documentcloud.org/documents/6405929-091320191420...](https://www.documentcloud.org/documents/6405929-09132019142056-0001.html) but there has never been a shortage of things he's said to make headlines. I'd recommend skipping the commentary/news/blogs on it and just forming your own opinion and going from there.

</comment></comment><comment> ur-whale So, like 27 SJWs out of how many people actually partitipating in the GNU movement?

Like my grand-father would say, "storm in a glass of water".

</comment><comment><USER6> I'm wondering if this is what it will take to finally push politics out of software development.

<comment><USER7> Decent behaviour respectful and inclusive to all?

<comment><USER8> But who should be responsible of deciding if Stallman was indecent or not inclusive and why?

<comment><USER9> Who should be responsible of deciding if _anyone_ is indecent or inclusive? Are decency and inclusivity even real?</comment></comment></comment></comment>


How can I help de-politicize HackerNews? - <AUTHOR> I'm interested in programming and all things programming related.  I hate gratuitous political posts in my RSS reader. Lately, I've noticed some pure political hit-pieces with zero relation to hacking in HN. How can I, as a member, help reduce this? <comment><USER2> > _How can I help de-politicize HackerNews?_

Short answer : Don't try.

There were many fora on the internet before PG created HN and many others have sprung up since then. The allure of HN is its mix of contributors, expert opinions and topics as well as the civility of the conversation(s). A forum focussed narrowly on "hacking" would soon read like a monograph and quite likely die shortly thereafter.

Instead of trying to change the offering, embrace the experience.

</comment><comment><USER3> Playing Devil's advocate: I personally don't care if you like or dislike political talk, either is fine for me, no strong opinion.

What's inherently wrong with political talk other than it makes [you] feel bad?

Politics certainly impacts technology (and technology politics, see gerrymandering in the US). Technology serves no purpose other than to bring efficiency into our lives (be it for entertainment or productivity, or ... ), so what's wrong with discussing politics as it relates to technology?

Or, what's wrong with discussing political problems, with hope that we can "hack politics?"

</comment><comment><USER4> This experiment should perhaps be mentioned here: [https://news.ycombinator.com/item?id=13108404](https://news.ycombinator.com/item?id=13108404)

</comment><comment><USER5> "As a member" \- it seems there's not much you could do except not up-vote or comment on them, and make a point to ignore such articles. They're trying to attract people's attention and occupy "mind space", so ignoring them could be a sensible way to respond? Or, counter-post with articles that are more relevant and meaningful to you/us?

</comment><comment><USER6> how do you feel about articles about raising venture capital?

</comment><comment><USER7> A solution would be to create 2 new categories on HN. "Tech talk" and "general topics". Then we should be able to subscribe to categories directly.

Unfortunately, user feedback loses its powerful when a product is already "successful".

</comment><comment><USER8> The best thing any of us can do, as a member, is to ignore it.</comment>


How to protect a company from employees. - <AUTHOR>

I am starting (together with a friend) a company in Mexico, we have been developing a web application by 1 year. We want to hire one or two programmers right now,  What recommendations do you have to protect our application ? <comment><USER2> Treat your people well and make sure you've got solid non-disclosure language in your NDA. Given how easy it is to duplicate a web app overall, what else can you do?

</comment><comment><AUTHOR> By the way our business model is Saas.</comment>


The Subtle Art of the Mathematical Conjecture - <AUTHOR> https://www.quantamagazine.org/the-subtle-art-of-the-mathematical-conjecture-20190507/ <comment><USER2> "a mathematician often finds herself engaged in an individual battle of the human mind against rigid logic"

The platonist view is assumed all the way through the article. Why assume that maths and logic exist independently of the human mind rather than being just another product of our thought?

<comment><USER3> If two individuals who had no contact whatsoever reliably came up with the exact same ideas and structures, it is reasonable to view it as something objectively existing.

On the other hand, is this philosophical debate of any relevance?

</comment></comment><comment><USER4> Popular. Posted five times in the past week: [https://hn.algolia.com/?query=The%20Subtle%20Art%20of%20the%...](https://hn.algolia.com/?query=The%20Subtle%20Art%20of%20the%20Mathematical%20Conjecture&sort=byDate&dateRange=all&type=story&storyText=false&prefix&page=0)</comment>


The Octonion Math That Could Underpin Physics - <AUTHOR> https://www.quantamagazine.org/the-octonion-math-that-could-underpin-physics-20180720 <comment><USER2> I think this is the first article I've ever read about the octonions that didn't include the following John Baez quip:

"There are exactly four normed division algebras: the real numbers ($\R$), complex numbers ($\C$), quaternions ($\H$), and octonions ($\O$). The real numbers are the dependable breadwinner of the family, the complete ordered field we all rely on. The complex numbers are a slightly flashier but still respectable younger brother: not ordered, but algebraically complete. The quaternions, being noncommutative, are the eccentric cousin who is shunned at important family gatherings. But the octonions are the crazy old uncle nobody lets out of the attic: they are /nonassociative/."

<comment><USER3> Is there an easy explanation of what problems quaternion or octonions solve?

Imaginary numbers are needed to take the square root of a negative number, and complex numbers result from combining the new numbers with the real numbers. Complex numbers also allow solving roots that aren't found in just real numbers.

But I have no similar comparison of what I can do with a quaternion or octonion that I can't do with a complex number. I remember seeing some w based number system derived from the cube root of either 1 or -1 (forget which, but w and -w were the solutions that weren't 1 or -1), but it did all the same things that complex numbers do and was considered mostly uninteresting.

It also seems like there is a pattern to go infinitely beyond octonions, but they all behave identical to octonions, but are the octonions even needed in the same way complex numbers are needed, or do they just make some math problems easier to work with?

<comment><USER4> Historically, quaternions came about as a way to try to reason about three dimensional physics. I mean, complex numbers were obviously really nice -- two dimensional numbers you could meaningfully add, subtract, multiply and divide. But they were only 2-D and we live in a 3-D world and we want to do 3-D physics.

So Hamilton was trying really hard to find a way to have 3-dimensional numbers that behaved nicely, and he couldn't do it. But he did find 4-dimensional numbers -- the quaternions. And they were really neat. You can use them quite well for classical mechanics, and electromagnetism, and even special relativity. So, why don't we?

We look at Maxwell's equations of electromagnetism today, and they're really nice, single-line vector formulas. You can also write them as nice, single- line quaternion formulas. Our notion of vector didn't exist at the time the quaternions were first used, and it was a boon to have quaternion notation to simplify some of these physical laws. Vectors and quaternions competed for a bit, and vectors won since they generalize to arbitrary dimensions.

Hidden inside of quaternion multiplication, you can find the three-dimensional versions of the dot product and cross product. And they do have some theoretically interesting properties for number theory and abstract algebra. In the end, however, sometimes items are discarded in favor of better items. I'd rate quaternions as one of the coolest items that ultimately wound up in the discard pile.

<comment><USER5> Quaternions show up all the time in 3d graphics - they're how you represent rotation matrices without the problem of gimbal lock.

I don't know if that's significant but it was how I stumbled on the concept in high school when I was messing with Direct X.

<comment><USER6> Rotation matrices by themselves do not suffer from gimbal lock. I think you meant Euler angle representations with the rotations always applied in a consistent order around the pitch/yaw/roll axes.

<comment><USER7> Right. Just to add on, one reason Quaternions are still used in graphics (despite rotation matrices not suffering from gimbal lock either) is that they're easy to interpolate between, even if you have many.

If you just have two you can slerp (or not), but if you have a large number of them (weights from an animation system, for example), a basic weighted sum followed by normalizing is shockingly well behaved and extremely fast.

<comment><USER8> This is a timely comment. I've been aware of quaternions for rotation for decades but only learned yesterday that rotation matrices can be used for some use cases. I'd never heard this small fact until then and now I stumble across your comment!

</comment></comment></comment></comment></comment></comment></comment><comment><USER9> > There the game stops. Proof surfaced in 1898 that the reals, complex > numbers, quaternions and octonions are the only kinds of numbers that can be > added, subtracted, multiplied and divided.

1\. I think they meant "the only kinds of numbers __constructed in this way __". 2\. Sedenions can still be added, multiplied, subtracted and divided. it's just that multiplication and division lose most of their useful properties. With octonions you've already lost associativity and commutativity, though.

<comment><USER10> >it's just that multiplication and division lose most of their useful properties.

Specifically they lose the property of not having zero divisors.

There exists sedonions a,b != 0 such that ab = 0

<comment><USER11> Another (related) property that fails is that inverses stop being useful for cancellation. Inverses still exist, for every p there's a q with pq = qp = 1, but if you've got an equation ap = b you can't cancel to get a = bq, because we don't have associativity. The left hand side (ap)q doesn't equal a(pq), so you can't reduce it to a.

Of course associativity doesn't hold in the octonions either, but it holds just enough for cancellation to work.

<comment><USER9> Yeah, octonion multiplication is alternative.

</comment></comment></comment></comment><comment><USER12> I think the following quote is the QED for academia ruining any chance at actual research:

"What I had was an out-of-control intuition that these algebras were key to understanding particle physics, and I was willing to follow this intuition off a cliff if need be. Some might say I did."

<comment><USER13> It's my understanding that most of Einstein's theory was the product of intuition, backed up after-the-fact with mathematics and experimentation. Intuition isn't a bad compass, as long as you can set it aside if reality measurably contradicts it. In fairness, Einstein never accepted quantum mechanics because they flew in the face of his intuition, but it still got him pretty far.

<comment><USER14> This is very false. Einstein's reputation was built on explaining known phenomena such as the photoelectric effect and Brownian motion. Special relativity was heavily motivated by a pile of puzzling evidence and a bunch of existing mathematics.

<comment><USER12> And he funded his studies, initially, as a hobby alongside a job. We've not progressed very far if ground breaking research almost requires a person to find a novel study path.

<comment><USER15> What do you mean by "novel study path" here? Funding yourself with money received from a job?

On my first reading I took "novel study path" to mean new research techniques or something along those lines, which seems obvious and is not likely what you meant.

<comment><USER12> Either applies really.

</comment></comment></comment></comment></comment></comment><comment><USER16> It's rather amusing that the author assumes that non-associtiave objects are "weird" for physicists (or at least that was my reading), since the velocity addition formula is in general non-associative and that has been extensively studied.

(I remember three separate occasions in my undergrad particle physics class where we actually went through all the calculations involved with the velocity addition formula and finally saw that SOL was wacky).

[https://en.wikipedia.org/wiki/Velocity- addition_formula](https://en.wikipedia.org/wiki/Velocity-addition_formula)

I wonder if that is uncommon or if the article is just a bit ungenerous towards our understanding of non-associative objects.

<comment><USER17> To be fair, one never talks of relativistic "velocities" beyond undergrad physics. It is much easier to talk about Lorentz "boosts", and as members of a Lie Group, they are associative, though not commutative.

<comment><USER18> This. It's better to just make the full leap into spacetime geometry (4-vectors and 4-tensors) than keep trying to slice it into annoying 3-vectors.

</comment></comment></comment><comment><USER19> I've been exploring this idea as well however I have a hunch it's not actually octonions but dual quaternions as they are the perfect formalism for representing 3d movement over time.

And to add to that, the are a Lie group I.e. they are anticommutative I.e. AB=-BA.

I've also been exploring this relationship between dual quaternions and linear logic. It's pretty wild. I'm curious if anyone has any opinions on this.

<comment><USER20> Do you have an understanding of Clifford algebras? I've read a little about them here on hn, and they seem quite powerful. I don't understand them enough to know if they could also be an appropriate abstraction.

<comment><USER19> Yes! Dual quaternions are a Cl(2,0,1) Clifford algebra. Good ol Cliffy invented them too.

[http://www.chinedufn.com/dual-quaternion-shader- explained/](http://www.chinedufn.com/dual-quaternion-shader-explained/)

Check the guy on the right getting deformed like an idiot. Compare it with the smooth criminal on the right.

<comment><USER21> > [http://www.chinedufn.com/dual-quaternion-shader- > explained/](http://www.chinedufn.com/dual-quaternion-shader-explained/)

Offset curve deformations blow dual quaternion's out of the water for rigging!

<comment><USER19> Tell me more. I briefly looked it up and I do agree it does look somewhat nicer. However how's the performance.

<comment><USER21> Fast enough for use in live character rigs in film running on the CPU -- I know the technique is used at Sony Imageworks and at Dreamworks. I can't comment on whether the method is suitable for live rigs in games, or how it would translate the GPU.

</comment></comment></comment></comment></comment></comment><comment><USER22> This reminds me a bit of atomic orbitals and how they're based on spherical harmonics. I was curious why there were e.g., eight electron 'sockets' in the second shell. Eight seemed like a very arbitrary number to me and my high school chemistry teacher's inability to explain at the time did it's share to put me off chemistry.

Many years later I remembered my old question and started looking it up. It turns out that eight is the sum of 1+3+3+1 perhaps similarly to what's in the article.

Spherical harmonics ends up giving rise to a three dimensional 'overtone' series (borrowing from my understanding of music theory). In the first order there's only one mode of vibration. In the second order there are three additional modes. The summands above are something like positive and negative degrees of freedom for each mode in the second shell.

Here's a diagram of what the modes look like in each order:

[https://i.ytimg.com/vi/OkDYbIhisZE/maxresdefault.jpg](https://i.ytimg.com/vi/OkDYbIhisZE/maxresdefault.jpg)

...and here's an animation of a sphere undergoing the differing modes of vibration:

[https://youtu.be/EcKgJhFdtEY](https://youtu.be/EcKgJhFdtEY)

If I understand correctly, the math related to atomic orbitals can be described with 3 dimensions of space: x, y and z plus one more orthogonal dimension of frequency/time which would mean quaternions would be most directly applicable?

</comment><comment><USER23> "Proof surfaced in 1898 that the reals, complex numbers, quaternions and octonions are the only kinds of numbers that can be added, subtracted, multiplied and divided. "

Not true. Any field (in the algebra sense) has these properties. [1]

Quaternions and octnonions also have weirder properties: quaternions are non- commutatve (j _k=-k_ j) and octnonions are non-associative: a(bc) != (ab)c.

I think the article meant these are the only Euclidean Hurwitz algebras [2], which is a far cry from the claim.

[1] [https://en.wikipedia.org/wiki/Field_(mathematics)](https://en.wikipedia.org/wiki/Field_\(mathematics\)) [2] [https://en.wikipedia.org/wiki/Hurwitz%27s_theorem_(compositi...](https://en.wikipedia.org/wiki/Hurwitz%27s_theorem_\(composition_algebras\))

<comment><USER24> It's in the article towards the end, but these are the only kinds of ... "over real numbers," which constraint Furey believes may be only an approximation.

<comment><USER25> Even when adding "over the real number", the claim in the article is wrong: R(x), the algebra of rational functions of one variable with real coefficients is a field, and a module over R containing a isomorphic image of R as a subfield.

You really do need the additional constraint of the Hurwitz form to restrict the possibilities to R, C, H, O ...

(Of course this has nothing to do with the work of Furey - I'm just seconding that the claim _in the article_ is incomplete and inexact as worded.)

</comment></comment></comment><comment><USER26> > "Because while it's very easy to imagine noncommutative situations — putting > on shoes then socks is different from socks then shoes — it's very difficult > to think of a nonassociative situation." If, instead of putting on socks > then shoes, you first put your socks into your shoes, technically you should > still then be able to put your feet into both and get the same result. "The > parentheses feel artificial."

> The octonions' seemingly unphysical nonassociativity has crippled many > physicists' efforts to exploit them.

I'd say nonassociativity is extremely physical property. And example with shoes and socks, if anything, shows just that. In idealised mathematical model, if you put socks inside shoes and then insert feet into socks you could end up with same thing as if you put feet in socks an then both in shoes. But in real world or just accurate model of physical world you'll end up with very different result.

I feel that nonassociativity is what's missing to take into account time which unidirrctuonality is suspiciously missing from almost all of the physics.

<comment><USER27> If you're looking for a deep look at time -- a Total Perspective Vortex, I'd recommend "Spontaneous Inflation and the Origin of the Arrow of Time".

[https://arxiv.org/abs/hep-th/0410270](https://arxiv.org/abs/hep-th/0410270)

<comment><USER26> I don't know. Unidirectionality of time just feels like something that should be everywhere. Nonassociativity of basic math that governs all of matter seems for me to be a better source for it than inflation or entropy or gravity or any one specific thing.

</comment></comment></comment><comment><USER28> How does this tie into E8? Does this work validate Garret Lissi or is it parallel?

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

<comment><USER29> I remember hearing Garret Lisi's TED talk on the E8 ToE (link below) years ago and hoping that components of the theory would eventually come to light through advances in particle physics research. Has anyone heard anything supportive or to the contrary since?

TED Talk: [https://www.ted.com/talks/garrett_lisi_on_his_theory_of_ever...](https://www.ted.com/talks/garrett_lisi_on_his_theory_of_everything)

Paper: [https://arxiv.org/abs/0711.0770](https://arxiv.org/abs/0711.0770)

 _Edit_ I remember seeing an update from him two years ago where he addresses some of the criticism: [https://www.quora.com/What-is-the-status-of-Garrett- Lisis-E8...](https://www.quora.com/What-is-the-status-of-Garrett- Lisis-E8-Theory)

<comment><USER30> There's been some criticism of his work, back when it first came out.

I'm fuzzy on the details now, but the criticism was along the lines of "mixing things together that don't make sense".

<comment><USER31> I remember something about being unable to do any CP violation.

</comment></comment></comment></comment><comment><USER32> Why are complex numbers not called duonions then?

<comment><USER11> And why are the real numbers not called "onions"?

<comment><USER33> Obviously due to potential confusion with the zero-dimensional numbering system, "0nions".

<comment><USER34> Hehe, well we could have unions & oneions. For some reason as I'm reading about octonions, I keep picturing 8-cloved garlic.

</comment></comment></comment></comment><comment><USER35> I think that maybe if you lock a mathematical physicist in a box forever with an x-TeV collider without letting them upgrade it, they will eventually find a theory that hits all of the datapoints and depending on their philosophical weakness then declare it "final."

<comment><USER11> Surely what we're looking for is the _simplest_ theory among the theories that hit all the datapoints. That's the theory that's most likely to be the "Theory of Everything" and therefore to continue working when we upgrade our collider.

<comment><USER35> Why would the simplest theory be the most likely to be true?

<comment><USER36> That's a big topic, and the definition of simple is subtle. I recommend David Deutsch's book _The Beginning of Infinity_ for an accessible introduction to what makes one theory better than another when they both fit the observations.

<comment><USER35> One theory might be better than another when they both fit the observations, but you can't say which one is true-er. For example, were Newton been presented with GR but only allowed his contemporary evidence, he should not conclude that classical gravitation is more true than GR on the grounds that he doesn't have any evidence for the additional complexity.

<comment><USER37> I think you are wrong. If he is following the scientific method, and he doesn't have evidence, he should 'conclude' that.

The key is that in science, you never 'conclude' (in the sense of finalize) anything. Everything is temporal until new evidence deny your current understanding.

</comment></comment></comment></comment></comment></comment><comment> Ono-Sendai I have to disagree that quaternions underlie Special Relativity. Although special relativity does use 4-vectors, those aren't quaternions.

<comment><USER14> I remember going down that path when I was an undergraduate. Fortunately I had a very experienced theorist to hand who explained that, yes, people did try that, but stopped bothering because it doesn't generalize to general relativity, and there was no point keeping two mathematical toolboxes around when you could have one.

<comment><USER38> Clifford algebras are great for both SR and GR and have all the properties that one likes in quaternions (and more)

</comment></comment></comment><comment><USER39> As a math graduate, octonions (and quaternions) at least to our group, was something that got discussed once or twice and not much after that. However, I would not call them weird or unusual, at least not more _weird_ than something like a near-ring which similarly simply drops one of the common assumptions for rings (I'm not sure which, actually). As mentioned in some of the comments, nonassociative fields do get studied. Studying not necessarily commutative structures such as (all) groups is in fact an even much more common thing to do.

I would say that studying octonions exclusively would be something I personally would avoid, as I would rather try to study the four structures (reals to octnonions) together, either more generally (e.g., group theory and ring theory) or more abstractly (e.g., as members of categories) and form an opinion on whether I think octonions in particular are useful for the questions that I want to ask.

That is not to say that the research here is not interesting, but it is difficult to judge that from "popular" mathematics articles. I got the impression that the author of the article places a much higher priority on the pictures accompanying the post.

I remember that I found it interesting that studying the four dimensional spacetime bears more fruit than stopping at three space dimensions, and that at the same time from complex numbers the next structure ends up also having four dimensions (i.e., being modelled by 4-tuples). However, apart from being interesting in this narrow sense, I do not know whether this suggests any creative yet precise mathematical questions.

</comment><comment><USER40> Why do I feel like the octonions are likely related to the spin networks of LQG (loop quantum gravity). The non-associative property is probably key to explaining how change in space is propagated through the spin networks. And thus why time is directional..

</comment><comment><USER41> In the approach from the article it seems as you are picking a mathematical structure in the middle of nowhere with the universe faintly visible at the horizon and then you start wandering around hoping that you will stumble across a path leading to the horizon.

But there don't seem to be many reason to believe that such a path exists, there are countless mathematical objects you could pick as a starting point and almost none of them have a path leading to the universe at the horizon. And even even of those with path going roughly into the right direction many will take a turn before you arrive at your destination.

So it seems much more promising to me to start at the universe and the mathematical structures describing our observations in a straight forward way and then explore from there the surrounding mathematical structures to see if they are a better fit, suggest new ideas, or whatever.

<comment><USER42> > In the approach from the article it seems as you are picking a mathematical > structure in the middle of nowhere

Quaternions were very popular way of expressing the "classical" physics around the 19th century (and the vector algebra we know today is in some ways just a derivative of quaternion algebra). Complex numbers are extremely useful in many fields even today. It's hardly in the middle of nowhere.

<comment><USER41> But the article is not really talking about quaternions - which are surly a useful tool, probably best known for the nice way in which they can describe rotations - but about R⊗C⊗H⊗O. And it's at the very least not obvious that this thing is anywhere close to where they journey is hopped to lead to.

<comment><USER42> Octonions are to quaternions as are quaternions to complex numbers (and complex numbers to reals). This is called "Cayley construction" iirc.

<comment><USER41> Sure, but the structure the article is about is the tensor product of the four algebras which is an algebra with 64 real dimensions.

</comment></comment></comment></comment></comment><comment><USER43> The really interesting part in all this, is that we're still reduced to bouncing values off of imaginary numbers to obtain accurate readings.

We toss our known quantities into a void, anticipating that if some impossible, imaginary thing really can fill the gap, and if or when it does, we'll catch the rebound off of it, and the rest of the universe proceeds predictably.

Somehow, we're always put into a position where we have to close our eyes, fly blind for some undisclosed intervening moment of unspecified length, and when we open our eyes again, we're grounded by familiar territory again.

It really is kind of stultifying.

</comment><comment><USER44> I never liked the name complex numbers. Something like dual numbers would have been much nicer and more descriptive.

By the way any idea why they don't mention the sedenion numbers? [https://en.m.wikipedia.org/wiki/Sedenion](https://en.m.wikipedia.org/wiki/Sedenion)

</comment><comment><USER45> Pachimari, of course, is the official mascot of octonions everywhere: [https://kotaku.com/overwatchs-little-onion-octopus-has- becom...](https://kotaku.com/overwatchs-little-onion-octopus-has-become-a- sensation-1820855871)

</comment><comment><USER46> > They "imagined that the next bit of progress will come from some new pieces > being dropped onto the table, [rather than] from thinking harder about the > pieces we already have,"

When the best minds we have divide into two camps, one saying that (a) "with X and Y we don't have enough information to solve Z" and the other saying (b) we do but we need to think harder, the first camp builds a particle collider, the other creates what, string theory? Aren't we doing "fuzzy science" here?

It seems that the experts in one of the camps should go back and retrace their steps because somewhere along the line they made an assumption based on some data that they (I assume) forgot to encode into their equations and now they have trouble taking it to the next level. Why is it not clear to us that eiher a or b is true?

</comment><comment><USER24> So, did Furey get a faculty job or can she be viewed with her accordion somewhere?

<comment><USER47> FWIW, I'll certainly tell my department chair in New Orleans about her if they're doing another faculty search soon. Maybe she can have her cake and eat it too that way.

</comment></comment><comment><USER48> I wonder how many hardcore Harry Potter fans are smiling at the 1st photograph?

</comment><comment><USER49> This article reminded me of wave function being a complex-valued function! Does this have anything to do with octonion, nature's symmetries/invariants or the standard model?

</comment><comment><USER50> Are we getting to the point where physics actually isn't showing any more useful properties for us to leverage?

Isn't that kind of what it would mean if it turned out octonions were at its core?

</comment><comment><USER51> A layman's quest to understand wtf this is...

>In mathematics, the octonions are a normed division algebra over the real numbers .

wtf is a normed division algebra??

>In mathematics, Hurwitz's theorem is a theorem [...] solving the Hurwitz problem for finite-dimensional unital real non-associative algebras endowed with a positive-definite quadratic form.

... right.

I have the same problem when I try to understand anything statistics related, I get hit by a barrage of unknown words and my brain just melts.

Is there any place that explains mathematical concepts in ... different ways?

<comment><USER52> Well yeah, math books...

Jokes aside, i too think we need a new framework for divulgating math that actually tells what you need to know, without just handwaving at it, BUT without the amount of technical details of a mathematics class.

What do you know, i think this is Possible, too.. You can communicate a surprising amount of information if you use words properly.

Of course, since this has never been done except from basic maths, it would be quite a task to embark in, and one would only do it if it made economic sense..

<comment><USER53> > Jokes aside, i too think we need a new framework for divulgating math that > actually tells what you need to know, without just handwaving at it, BUT > without the amount of technical details of a mathematics class.

oh man, have i got bad news for you about the amount of technical detail present in math classes.

</comment></comment></comment><comment><USER54> Can anyone expand on the current successful similarities between octions and the standard model in plain English?

</comment><comment><USER55> If it goes: 1D, 2D, 4D, 8D, why does it stop at 8? Is there a hexadeconion?

<comment><USER41> They are called sedenions [1] and you can repeat the construction taking you one level up [2] infinitely.

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

[2] [https://en.wikipedia.org/wiki/Cayley–Dickson_construction](https://en.wikipedia.org/wiki/Cayley–Dickson_construction)

</comment></comment><comment><USER56> 'Looking like an interplanetary traveler, with choppy silver bangs that taper to a point between piercing blue eyes' WTF? for a few minutes, I thought this was a serious article by a serious journalist. Apparently not.

</comment><comment><USER57> If anyone can make octonions cool it would that physicist

</comment><comment><USER58> Her name is Cohl Furey, that is SO COOL!

</comment><comment><USER59> [https://motls.blogspot.com/2018/07/cohl-furey-understands- ne...](https://motls.blogspot.com/2018/07/cohl-furey-understands-neither- field.html)</comment>


Nim Chimpsky: the chimp they tried to turn into a human - <AUTHOR> http://www.guardian.co.uk/film/2011/jul/24/project-nim-chimpsky-chimpanzee-language

<comment><USER2> Watched a fantastic movie about this, Project Nim</comment>