A.I. Shows Promise as a Physician Assistant - <AUTHOR> https://www.nytimes.com/2019/02/11/health/artificial-intelligence-medical-diagnosis.html <comment><USER3> 1) "The equipment is never the same. You have to make sure the data is anonymized. Even if you get permission, it is a massive amount of work." This is literally true, but also, not something I would want to change. Our PHI should be anonymized, and we should have the right to grant or deny permission for how our most delicate personal data is used.

2) "When tested on unlabeled data, the software could rival the performance of experienced physicians. It was more than 90 percent accurate at diagnosing asthma; the accuracy of physicians in the study ranged from 80 to 94 percent."

And this is where "physician support tools" have always fallen down, and was the give-away I was expecting in the article. There are two type of ways of assisting diagnosis: (a) given this mass of data, what does the patient have? and (b) given this mass of data, does this patient likely have asthma?

(B) is relatively easy. This is not something physicians need help with. It's also what people keep building physician support tools to do. Because it's easy. Note the article gives away that they seem to be working on (b), although the hype machine - as always - implicitly suggests they're working on (a).

I want (a). I was involved with a couple of patients recently that had their amyloid cardiomyopathy missed. I decided to refresh myself on the topic. The first sentence in the relevant text was "The key to diagnosing amyloid cardiomyopathy is remembering that it exists." (a) could have helped those patients. (b) could not - if their original physicians - any of them - <USER2> "remember[ed] it exists" he would not have needed AI to help diagnose it. It would have been trivial. Those docs didn't even make a mistake, per se - it's such a stupidly rare condition and, in those patients, manifested so subtly, that connecting the dots was reasonably unreasonable. That's where AI would be helpful. Not "does this kid have (obvious and common and extremely easily identified condition)?"

<comment><USER4> If you can answer "given this mass of data, does this patient likely have X?" for any X, then (a) is as easy as iterating through all possible values of X and returning those where the answer is "yes". Remembering that some rare disease exists may be hard for humans, but is the easiest part for a computer. So even though some specific trial might be on (b) where X = "asthma", everyone working on (b) is also implicitly working on (a).

<comment><USER5> > Remembering that some rare disease exists may be hard for humans, but is the > easiest part for a computer.

I don't think that's necessarily true. The rarer a disease, the rarer the data and therefore the harder it is to train a computer to recognize it.

</comment></comment></comment><comment><USER6> > It could be years before deep-learning systems are deployed in emergency > rooms and clinics.

Yep. Caduceus was an expert system that did this back in 1980. [https://en.wikipedia.org/wiki/CADUCEUS_(expert_system)](https://en.wikipedia.org/wiki/CADUCEUS_\(expert_system\))

Since then many bayesian and decision tree diagnosis systems were created and performed comparably as well. But none were ever deployed, largely because some sort of nurse or PA is still needed to do the hard part -- the physical exam. Diagnosis using existing data is easy; it's the acquisition of all the necessary data that's hard.

Until software/AI can replace _all_ that a health pro does, especially the physical exam, it will remain a niche tool used only in the path lab or the back offices of insurance companies.

<comment><USER7> The common argument I've heard is that these systems won't replace nurses/PAs, but rather family physicians, whose diagnosis and referral skills may become redundant in the face of a nurse/PA to collect data and a machine learning system to understand the data and make recommendations in response to it (e.g., request more data/tests, make a diagnosis, make a referral, etc.).

</comment></comment><comment><USER8> _Many organizations, including Google, are developing and testing systems that analyze electronic health records in an effort to flag medical conditions such as osteoporosis, diabetes, hypertension and heart failure._

I used to have to wait a week for lab results to be mailed.

Now I'll have to log in and sync my browser to read them. But only after I confirm my cell phone number and enter the code in a confirmation email.

Oh, and here's some recommended links based on your family, er browsing history.

</comment><comment><USER9> I feel embarrassed saying this but if we consider Alexa a certain form of "AI" then the talk I've heard about "VoiceOps" would be super duper helpful.

I can't say this without sounding extremely lazy, but to be able to ask my computer "what is the IP address of that server I just spun up" and other simple-intermediate queries would be game changer for SREs and Sysadmins.

<comment><USER10> I've actually been talking to a lot of people recently about these kind of concepts - figuring out what kind of problems people are having that could be solved with current levels of AI speech/language understanding.

Would I be able to drop you an email or PM with a few questions?</comment></comment>


The Apple Online Store is down too  - <AUTHOR> http://store.apple.com/

<comment><USER2> This can't be a good thing.

</comment><comment><USER3> oh hell naw!</comment>


Deanonymizing Tor Circuits - <AUTHOR> https://www.hackerfactor.com/blog/index.php?/archives/868-Deanonymizing-Tor-Circuits.html <comment><USER2> I think a lot of comments here are forgetting it takes months to be considered a trusted guard node by TOR. Unless you have hundreds of these and a lot of time and patience, and somehow knock off all of the non-malicious guard-nodes + have your "aged" guard nodes set up, this attack will be very difficult to conduct.

<comment><USER3> Which the larger countries do. And the main point of Tor is to evade serious adversaries isn't it? If you're not anonymous from nation states when using Tor, then what will protect whistle-blowers and investigative journalists and dissidents? VPNs can be ordered to turn over data by courts and you can never be sure a "no logs" VPN does what it says. Tor is the only viable alternative and we know it can be at least seriously compromised by the bigger nations.

<comment><USER4> Has there been any known case where a person using Tor has been tracked down and put into curt, without human mistake that lead to his de-anonymization?

<comment><USER5> Yes. See [https://news.ycombinator.com/item?id=22215126](https://news.ycombinator.com/item?id=22215126)

Not one person. Hundreds, maybe thousands. Because of a exploited vulnerability, and failure to pay attention to an upsurge in suspicious relays.

Unless you consider that the mistake was using Tor directly, rather than through a VPN service.

<comment><USER6> [https://blog.torproject.org/tor-security-advisory-relay- earl...](https://blog.torproject.org/tor-security-advisory-relay-early- traffic-confirmation-attack)

A bit more detail would be welcome about those "Hundreds, maybe thousands" of persons. Clearly the security researcher did find a vulnerability in the protocol and confirmed it by unmasking users, but I don't see the support for people getting "tracked down and put into [court]".

More important, what purpose is there to reference a 5 year old patched security vulnearbility? The same year as the above vulnerability was found in Tor, HTTPS was also broken with Heartbleed. The only fool-proof security is security in so many layers that it become statistically unlikely to cause a negative impact.

<comment><USER5> The issue isn't that the CMU people exploited the "relay early" bug. It's that the FBI subpoenaed all their data, tracked down onion services, and served malware.

This is just the outcome from busting one site, PlayPen:

        At least 350 U.S.-based individuals arrested
        25 producers of child pornography prosecuted
        51 hands-on abusers prosecuted
        55 American children successfully identified or rescued
        548 international arrests, with 296 sexually abused children identified or rescued

[https://www.fbi.gov/news/stories/playpen-creator- sentenced-t...](https://www.fbi.gov/news/stories/playpen-creator-sentenced- to-30-years)

<comment><USER6> While that linked article does not directly talk about relay early, this article does: [https://blog.torproject.org/did-fbi-pay-university-attack- to...](https://blog.torproject.org/did-fbi-pay-university-attack-tor-users)

The article says that they likely did not have a warrant and simply just went and hired the researcher directly.

But fair enough, the claim that hundreds did get tracked down and arrested, due to a bug found by a security researcher after getting hired by the FBI, is true.

People selling zero days vulnerabilities is a major problem to security. Sadly it is something which new threat models need to take into consideration. The Tor Project did change how the Tor browser bundle updates, and I suspect this event did also caused some ripples in the project in how much they can trust researchers.

</comment></comment></comment></comment></comment></comment></comment><comment><USER7> First: it seems like the author has come up with a number of useful custom modifications to the Tor daemon to mitigate common attacks against onion operators. Why not work with the Tor Project to upstream some of the more useful ones, as well as the additional debugging information? Reading past Hacker Factor posts, is it just me, or is there a tone of slight disdain towards the Tor project?

Second:

>However, there's a second attack. The attacker can run one or more hostile guard nodes. If he can knock me off enough guards, my tor daemon will eventually choose one of his guards. Then he can identify my actual network address and directly attack my server. (This happened to me once.)

A guard node is going to get a lot of traffic from both onion services and normal Tor users. How can an evil guard node tell which IP belongs to the author's server?

Overall, this is startling to read. History suggests that it is only a matter of time before an onion service gets unmasked by the latest attack on the Tor network.

<comment><USER8> Onion services are incapable of resisting a determined government-scale attacker. Just filter Tor traffic to random groups of users for like 10 seconds, find one such groups that prevents the target onion service from being routed. Bissect until you locate a precise node.

IMO, Tor is to be used to escape censorship as a reader or host services anonymously in not tech-savvy governments (which are becoming increasingly rare).

In the end, Tor only buys 10 to 20 years of freedom until governments figure out what to outlaw and filter. Censorship is a political problem, technical solutions provide a temporary hotfix, but the political problem has to be solved at one point.

<comment><USER9> > Just filter Tor traffic to random groups of users for like 10 seconds, find > one such groups that prevents the target onion service from being routed. > Bissect until you locate a precise node.

That only works if you have the ability to filter out Tor traffic in the first place. (In which case, why not just preemptively block all Tor traffic in your country? Problem solved.) But Tor has systems in place designed specifically to prevent that sort of blocking by disguising Tor traffic as other, more common traffic types (like HTTP).

There's also no guarantee that the Tor service in question is running on a host that's under your government's control. Cloud hosting is pretty common these days.

<comment><USER8> Yes, you can ban Tor altogether and be done with the whole thing. It is doable and there is no technical workaround for it.

The scenario I am proposing is actually worse: you use the feeling of anonymity Tor proposes to uncover opponents. Yes, my tactic proposes you have a backdoor into all of ISP's infrastructure. I don't see that as a crazy requirement for most countries, even democracies.

Disguising Tor traffic does not work well, and China has deployed several years ago already a tech that recognizes weird streams.

Yes, you could be cloud hosting from outside the country. In the case of China though, that's likely to not work as most encrypted traffic crossing the border gets dropped (I guess unless it is HTTPS from a whitelisted source )

</comment></comment></comment></comment><comment><USER10>
      ExcludeExitNodes {br}

Why are brazilian IP addresses associated with abuse? Lots of sites refuse to respond to my browser because of this.

<comment><USER11> Looks like it primarily comes from two ASN's in Brazil: CLARO S.A. (AS28573) and TELEFÔNICA BRASIL S.A (AS18881). Interestingly, it looks like Brazil is right up there with Russia when it comes to total number of risky ASN's.

source: [https://www.recordedfuture.com/asn-blocklist- analysis/](https://www.recordedfuture.com/asn-blocklist-analysis/)

</comment></comment><comment><USER12> > _many bots will only do one HTTP connection at a time (single threaded)_

Is it only service admins who do such detective work, or do admins of intermediate nodes also try to filter out bots? I wonder if simple API calls wouldn't get caught in the crossfire.

<comment><USER9> Intermediate nodes can't see HTTP connections. Tor traffic is encrypted.

</comment></comment><comment><USER13> Why would people spend effort trying to deanonymize an Internet Archive server? Are try trying to deanonymize every single hidden service?

And why would they try to DDOS the services once deanonymized? I don't see how anyone would gain anything from that. If you DDOS some big website you get famous from all the news articles being written about you, but DDOSing a hidden service won't make you famous.

<comment><USER14> I don't know this attacker's reason. I only see the attack.

But I can offer some baseless suspicions:

I'm forwarding traffic from Tor to the Internet Archive. During the last French election, someone DoS'ed most of their media outlets. As a result, lots of French people used Tor to access the current news from the Internet Archive's collection. Shortly after that, someone tried to DDoS my onion service.

With all of the voting and elections and the impeachment vote coming up, I'm expecting attacks since the Internet Archive stores lots of information that the current administration tried to remove from the Internet.

Then again, it could be a "researcher", or just someone seeing if it can be done. Perhaps they will decide what they want to do after their attack succeeds.

<comment><USER15> Perhaps countries that have already blocked the Internet Archive? But Tor users can already access it through Tor without a hidden service.

If the IA itself was DoSed then wouldn't your relay stop working?

<comment><USER16> random guess: the servers are reached via anycast. if you DDoS from the US, you'll take down access from the US, but not from other regions.

<comment><USER17> It's not much of a DDoS if it's from a single country.

<comment><USER18> That's pretty invalid — I often see large attacks that are almost entirely made up of bots from one country.

<comment><USER19> I've even seen 100+ Gbps from a single ASN in a single country.

</comment></comment></comment></comment></comment></comment></comment><comment><USER3> Also is it not weaker from an anonymity standpoint for the tor deamon to choose the same nation for the entire Tor circuit? I just fired up Tor Browser, navigated to the Tor Blog and this is what I get:

[https://imgur.com/a/j7JZFVl](https://imgur.com/a/j7JZFVl)

<comment><USER20> This has been mentioned on the tor irc several times and also on some other places. No one cared ...

</comment></comment><comment><USER21> Why do you suppose the Tor project has been so resistant to mitigating this class of attack? In particular, the proposal to require that rendezvous nodes be publicly listed seems sensible to me, and I wasn't immediately able to find any Tor bugs on the subject.

<comment><USER20> That's a good question indeed. I don't have an answer but some people got similar results when pointing out some issues internally. Only when publishing those on the mail list where everyone can read it things started to gain some traction.

"In April 2018 a Tor core member — the most active Tor Project person on that closed mailing list — made an attempt to initiate a "do not do" relay requirements list to improve and streamline the handling of malicious Tor relay reports. (I'm not mentioning his name since he does not want to be publicly associated with bad-relays handling for safety reasons.) Unfortunately also this attempt failed since no Tor directory authority operator answered. (Tor directory authorities are required to enforce any Tor network wide rules unless it is part of the tor code itself.)

Starting with June 2019, after multiple reports about suspicious relays remained with no reaction I stopped sending them to the list. Occasionally I sent some suspicious relay groups to the public tor-talk mailing list instead — which ironically was more fruitful."

[https://medium.com/@nusenu/the-growing-problem-of- malicious-...](https://medium.com/@nusenu/the-growing-problem-of-malicious- relays-on-the-tor-network-2f14198af548?source=</comment></comment><comment>---5</comment><comment></comment><comment></comment><comment>)

Even more ironical, the very person which reported that issue and similar ones (also on twitter) got his twitter account closed shortly afterwards (see other post on that site). So he has much less audience than before. Coincidence? Tinfoil hattery? Maybe. But certainly fishy.

</comment><comment> ur-whale I wonder if Wireguard is dynamic and lightweight enough to be hacked into re- implementing something like tor but that dynamically shuffles data paths in flight ?

<comment><USER5> Good point!

Actually, that works well enough with OpenVPN. I've managed a crude setup that switches two-hop nested VN chains at 10 minute intervals.[0]

I should also have mentioned the Orchid app for Android (and perhaps soon for iOS).[1] It implements dynamic multi-hop routing, and reputation-based route selection. As I understand it, commercial VPNs are providing OpenVPN servers for the network, and I would hope that each hop uses a different provider. Users buy bandwidth with supposedly anonymous Etherium-based cryptocurrency.

Orchid may provide privacy and anonymity that's at least comparable to do-it- yourself nested VPN chains, and perhaps comparable to Tor. In that you're distributing information and trust among multiple providers, who are paid anonymously. And it's obviously far less work than nested VPN chains. But as with Tor, there's the downside of trusting a complex system, which you likely won't understand well.

There's also the issue that current smartphones are so horribly insecure that using such tools arguably provides merely an illusion of security, privacy and anonymity.

0) [https://github.com/mirimir/vpnchains](https://github.com/mirimir/vpnchains)

1) [https://www.orchid.com/](https://www.orchid.com/)

</comment></comment><comment><USER3> Interesting related post: [https://www.reddit.com/r/encryption/comments/exjk9e/the_majo...](https://www.reddit.com/r/encryption/comments/exjk9e/the_majority_of_tor_nodes_are_in_the_14_eyes/)

</comment><comment><USER5> Good work!

> However, there's a second attack. The attacker can run one or more hostile > guard nodes. If he can knock me off enough guards, my tor daemon will > eventually choose one of his guards. Then he can identify my actual network > address and directly attack my server. (This happened to me once.)

I also worry about malicious guards. For local machines, I only hit Tor via nested VPN chains. So even if I'm using a malicious guard, the attacker will just get the IP of the exit VPN server.

For onion services, I typically use VMs in dedicated servers. And so I can put at least one VPN-gateway VM between the onion server VM and the Tor guard.

You could also get all of the guards from tor's state file, and hard-code them in torrc with EntryNode. That wouldn't prevent an attacker from taking the site offline, but at least they couldn't become your guard.

<comment><USER22> Your last point falls flat if they're already running a public guard though.

<comment><USER5> Why?

It "falls flat" if you're using a malicious guard. But then, you're already screwed, in that case.

<comment><USER22> Because they could already be running a node that's indexed and has the guard flag.

</comment></comment></comment></comment><comment><USER23> Bitcoin full nodes running over Tor can also be attacked similarly? I think yes however not sure and not every full node over Tor follows same configuration

<comment><USER24> All crypto services should be run through a decentralized, extra-codebase voting scheme to generate a confidence interval. Mature services like Bitcoin should have multiple clients and client versions available, geographically distributed across a range of networks, frustrating identification and creating an aggregate mechanism for rapidly detecting anomalous output and mitigating unknown attacks. I implemented this ~8 years ago.

<comment><USER23> 8 years ago? Can you share any link which has details about the implementation?

<comment><USER24> Sorry no, it was internal work at Kraken.

<comment><USER23> lol

</comment></comment></comment></comment></comment><comment><USER25> If you need a location hidden service it's wise to run your own guard.

<comment><USER14> Running your own guard is stupid unless you open it for the world to use.

If you're the only person using the guard, then the guard offers you zero anonymity.

And if lots of people use your guard, then make sure it doesn't violate your ISP's terms of service. (Most ISPs have a clause about residential customers not running public services.) Also, have a plan in place for when (not if) you receive legal notices about copyright infringement, child porn distribution, and other acts that could be criminal in your country/city.

<comment><USER5> As long as you're anonymous enough about it, I don't see why running your own [private bridge] is any less anonymous than using an unpublished bridge, or a snowflake proxy.

An adversary with lots of intercepts could certainly figure it out. But otherwise, how would anyone know?

And at least, it protects you from malicious guards.

Also, your point about violating a residential ISP's ToS is troubling. Because nobody in their right mind ought to be running any sort of Tor relay from home. It's a ~sure way to get your IP address on many blocklists.

And about getting notices, that only happens for exit relays. Not for guards and middle relays.

Edit: Actually, I meant running your own unpublished bridge, not guard. In the bridge torrc:

       ExitRelay 0
       BridgeRelay 1
       BridgeDistribution none
       PublishServerDescriptor 0

And in the client torrc:

       UseBridges 1
       UpdateBridgesFromAuthority 0
       Bridge [transport] IP:ORPort [fingerprint]

<comment><USER20> A malicious guard is just a malicious node. It can also be used as some other hop, or there can be non malicious nodes without a guard flag. I think there has been at least one publication taking a closer look at what malicious middle nodes can do.

I'm not familiar with bridges or the snowflake proxy but I think this would work:

Public bridges are public so no one cares about those. Now you run your own private bridge. First of all running your own leads directly back to you. Second it puts you on the list of even more paranoid people. Since you know and connect to that private bridge one can assume you trust that bridge for whatever reason which indicates some kind of "personal" relationship to that bridge.

The private bridge now connects to the second hop. This is a malicious one. The operator sees an IP which does not come from an official relay in the consensus. I don't know if a node knows he is in the middle (at least a guard and exit must know they are at the beginning and end of a chain, i guess?), but if he does he would now know that a private bridge is connecting to it. So you could enumerate private bridges.

If someone runs dozens of nodes, which is actually happening, this looks like a viable option. Correct me if I'm wrong.

<comment><USER5> Good questions :)

> First of all running your own leads directly back to you. Second it puts you > on the list of even more paranoid people.

It doesn't point to "me", at least in meatspace or even as Mirimir. It points to some anonymous persona, created specifically for that purpose. On its own Whonix instance, through its own nested VPN chain, and using its own multiply mixed Bitcoin. All totally disposable.

And to be clear, I'd use a _different_ anonymous persona for the onion service itself, created specifically for that purpose. With all the features described above.

> Since you know and connect to that private bridge one can assume you trust > that bridge for whatever reason which indicates some kind of "personal" > relationship to that bridge.

There are numerous private bridges, and many of them have only a few users. Perhaps even just one user.

> The private bridge now connects to the second hop. This is a malicious one. > The operator sees an IP which does not come from an official relay in the > consensus. I don't know if a node knows he is in the middle (at least a > guard and exit must know they are at the beginning and end of a chain, i > guess?), but if he does he would now know that a private bridge is > connecting to it. So you could enumerate private bridges.

Sure. Authoritarian regimes do that all the time.

But here's the thing. My Tor client will still only use that bridge. So it can't be tricked into using a malicious bridge. And I can change private bridges frequently, if I like. It's not at all hard to configure them.

</comment></comment></comment></comment></comment><comment><USER5> This finally hit the tor-dev list.[0] And Mike Perry's post is somewhat alarming.[1]

Some excerpts:

> The "Oddly, sometimes the connection would succeed" sentence is a red flag > sentence. If you are inclined to be paranoid, there is indeed a way to hide > a real attack in what looks like a simple ntohl() bug here.

> This "sometimes"connection behavior is often seen in tagging attacks, where > the adversary abuses Tor's AES-CTR mode stream-cipher-style properties to > XOR a tag at one end of a circuit, and undo that tag only if the other > endpoint is present. In this way, only the connections that actually succeed > are those that the adversary is _certain_ that they are in both positions in > the circuit (to perform Guard discovery, or if they are the Guard relay, to > confirm deanonymization).

> If you want to hide your tagging attack as what looks like a simple ntohl() > bug here, you send your intro2 with the reverse IP address. Then, when your > middle node suspects a candidate rend cell (via timing + circuit setup > fingerprinting, to have a guess), it can confirm this guess by undoing the > tag by XORing the cipherstream with ntohl(ip) XOR ip.

> <snip>

> Aka a correctly performing rend cell tag hidden in what looks like a very > common networking bug.

> This cipherstream tagging weakness has had a few proposals to fix, most > recently: > [https://gitweb.torproject.org/torspec.git/tree/proposals/295...](https://gitweb.torproject.org/torspec.git/tree/proposals/295-relay- > crypto-with-adl.txt)

> BUT DON'T PANIC: There is also an alternate explanation for the "sometimes > succeed" red flag in this particular case, other than a tagging attack.

> <snip>

> So most likely, this is just a poorly written Tor client, _but_ there still > is the possibility that it is an attack cleverly disguised as a poorly > written Tor client.. :/

> It may be a good idea for Neal's/our monitoring infrastructure to keep an > eye on this behavior too, for this reason, to test for the side channel > usage + rend XOR "correction" vs just dumb bug that is sometimes connecting > by getting lucky (and thus never properly reverses the rend IP address). If > this is indeed just a bug, when these rends do succeed, the IP address > should never be correct.

> The way to do that would be to build rend circuits using 3rd hops that you > (the service operator) control, so that that 3rd hop can check if the rend > succeeds because the TLS connection happened to be open (benign behavior) or > because the reversed ntohl() got corrected somehow (attack).

0) [https://lists.torproject.org/pipermail/tor- dev/2020-February...](https://lists.torproject.org/pipermail/tor- dev/2020-February/014146.html)

1) [https://lists.torproject.org/pipermail/tor- dev/2020-February...](https://lists.torproject.org/pipermail/tor- dev/2020-February/014154.html)

<comment><USER5> Also see [https://github.com/mikeperry- tor/vanguards](https://github.com/mikeperry-tor/vanguards)

> Even after deployment of the new v3 onion service protocol, the attacks > facing onion services are wide-ranging, and still require more extensive > modifications to fix in Tor-core itself.

> Because of this, we have decided to rapid-prototype these defenses in a > controller addon in order to make them available ahead of their official > Tor-core release, for onion services that require high security as soon as > possible.

</comment></comment><comment><USER26> The embedded images are ugly because of the downscaling (the URL contains &size=600).

<comment><USER14> Fixed.</comment></comment>


What If Time Really Exists? (2008) - <AUTHOR> https://arxiv.org/abs/0811.3772 <comment><USER2> Between modern physics suggesting time and space may be illusions, leading technologists agreeing that we're almost certainly in a simulated reality, and many ancient traditions being certain that this is all an illusion, I may have to have to go ahead and take this seriously....

<comment><USER3> The simulation argument comes from the fact that there a quite a lot of physics effects that are both surprising, and look an awful lot like dirty hacks that a programmer might put it.

Quantum physics looks a lot like lazy evaluation (State doesn't exist until "observed").

The speed of light seems like a hack to prevent an n squared problem of everything in the universe effecting everything at the same time.

<comment><USER4> > _Quantum physics looks a lot like lazy evaluation (State doesn 't exist > until "observed")._

This is a common misconception (¿among programmers?).

Let's think about the double slit experiment. [https://en.wikipedia.org/wiki/Double- slit_experiment](https://en.wikipedia.org/wiki/Double-slit_experiment)

In a classical word, you must simulate only one path. In a quantum word, you must simulate both. You don´t need some magical conscious observer to force the collapse of the wave function. A CCD detector of a camera or a simple wall is enough to force that the "wave" collapse into a "particle" and the detector or wall gets a small spot where the "particle" hits it.

A similar experiment is possible with spin, and you can use that to get a qbit. In a classical word, a qbit is simply a bit and you only have to chose between the 0 or 1 state and simulate it. In a quantum word, you must simulate both.

But it's worst with many qbits. Let's say you have a 10 qbits computer. In a classical word you pick a value for each of them and simulate each one, so the total computation is ~10. In a quantum word, you can combine any of the states of the 10 qbits and you must simulate the 1024 states.

So the idea that a quantum computers is better than the classical computer is opposed to the idea that quantum physics is some hack to reduce computational resources.

I think that the main problem is the quantum mechanics is weird, use a lot of linear algebra, but the calculations are somewhat straightforward and well defined. But the popularization explanations try to avoid the algebra and make some simplifications, so the explanation only keeps the weird part.

<comment><USER5> > In a classical word, you must simulate only one path. In a quantum word, you > must simulate both. You don´t need some magical conscious observer to force > the collapse of the wave function. A CCD detector of a camera or a simple > wall is enough to force that the "wave" collapse into a "particle" and the > detector or wall gets a small spot where the "particle" hits it.

This is a common misconception (among programmers). There's zero experimental evidence for the effect you mention, and zero theoretical derivation. Circumstances under which wave function collapses is the greatest mystery of QM.

<comment><USER6> [https://en.wikipedia.org/wiki/Bell's_theorem#Practical_exper...](https://en.wikipedia.org/wiki/Bell's_theorem#Practical_experiments_testing_Bell.27s_theorem)

<comment><USER7> That is not an answer to his objection.

If you follow the equations of the wave packet of the particle arriving to the wall (or CCD) detector, you then need to solve the equation of the interaction of the particle + all the particles in the wall or the CCD. The challenge of the collapse is that simulating anything beyond a few dozen quantum particles is too demanding. Mathematical models that simulate millions of particles need to make assumptions (typically they are too hot, too cold, too strongly bound, so you can ignore most effects - think 1D Ising model, Bose-Einstein Condensates, Photon gases, etc). But the full description of a particle + all particles in a detector still escapes us.

Therefore the transition between: superposition of paths -> particle lands at specific points has never been truly explored. The best description currently involves decoherence. Many theorems have been proven (and experiments done) in that area. The gist is that as you add particles to a system (2, 3, 4, 5, 10, ...) the superposition effects slowly cancel each other out. Another angle is the monogamy of entanglement (the more particles are entangled, the weaker the entanglement between any 2 particles). The idea of decoherence is that as things get larger, the weird effects of quantum physics become more "dilute". However, going from double slit to macroscopic reading still has many assumptions along the way.

Take the above explanation with a grain of salt (as I have tried to make it accessible).

</comment></comment></comment></comment></comment></comment><comment><USER8> What do we want? Time Travel.

When do we want it? Doesn't matter.

</comment><comment><USER9> Science is by definition incomplete. It only provides a means for proposing theories to test observed phenomenon, test them, and use them to extrapolate and make future predictions, which can invalidate or strengthen the theory.

e.g. we don't even know if the physics we have is universal or local to our observable corner, the only evidence we have is we haven't seen any evidence to disprove it, but that's not proof.

String theory could be considered dogma. But it at least provides means to test its predictions, its just that we are very very far off from ever getting close to that capability.

If we live in an illusion, its entirely possible and in fact likely that it is beyond our ability to even detect that. In fact that would be one of the first requirements of such a 'program'. You can should 'computer, end program!' all you like but the holodeck will just ignore you :)

There really is no point to wondering about the reality of time if it doesn't lead to anything we can test/influence or use to advance our understanding and so far there is none.

You could just say the entire universe is but one of infinite multiverses which are being continuously spawned in the cosmic sea, but that doesn't change anything.

<comment><USER10> > There really is no point to wondering about the reality of time if it > doesn't lead to anything we can test/influence or use to advance our > understanding and so far there is none.

I think this is wrong. There are some (possibly many) such apparently pointless questions that eventually lead to actual experiments. I remember that Einstein's book's about relativity theory starts with such questions. Off the top of my head, questions such as "how could you prove that two events in different places have happened at the same time."

I'd also argue that the whole concept of science came from the Philosophers from ancient Greece trying to answer such unanswerable questions. But this may require a longer dissertation :).

</comment></comment><comment><USER11> Seems like a lot of the problem with "time" is semantic. Do things change? Yes, and if that's the definition then it certainly exists.

But people don't generally see time like that, they think of it as some medium, or 4th dimension, that can possibly be traveled through. This kind of time does not exist (as much as anything can't exist). There are only particles and their positions. Traveling back in time would require moving every particle in the universe back to the state you want to experience. But this is not "traditional" time travel, just god-like influence over particles. Traveling back in time, in how people fantasize about it, would require copies of the universe being made every plank-time, that you can visit. And even that is just another 3d space that happens to look like one you saw before.

Time is chemical and physical reactions. The minimum amount of time (sorry) a reaction can take to happen is possibly plank-time. Nothing can "happen" faster than plank time. So time is possibly granular. If reactions stopped happening, time would stop.

That's one set of views.

<comment><USER12> Time is very much a dimension. You should read up on relativity.

<comment> semi-extrinsic In relativity we can model time as a dimension, with great success. But even there it is always evident that the time dimension is very different from the spatial ones; for one, we cannot travel in it. I believe GP is only saying this is the problem, ignoring that the time dimension is very special.

<comment><USER13> We can travel in it. We all are travelling in time and at different rates depending on our speed and gravity.

<comment><USER11> That's the sci-fi terminology and view that complicates and confuses the issue. Can reactions happen faster or slower, yes. No need to say "travel", that word has distinct meaning and connotations that lead to incorrect possibilities.

<comment><USER14> You have unknowingly stumbled into the heart of Special Relativity :) "travel" is the same all dimensions. If you think you are moving from (x1,y1,z1) to (x2,y2,z2) you are actually moving from (x1,y1,z1,t1) to (x2,y2,z2,t2). If you think you are staying put at (x1,y1,z1), then you are continuously moving from (x1,y1,z1,t1) to (x1,y1,z1,t2) to (x1,y1,z1,t3) and so on. The more you move in space, the less you move in time.

Also, when you put General Relativity in the picture, any sort of movement within this 4D space is possible (because the geometry of this space is wrapped) go to past, future, anything.

<comment><USER11> Your comment perfectly crystalizes everything I'm trying to say. You explain the relationship of time to space very nicely and succinctly and correctly, however you decided to use the word "move", which comes with a lot of 3d baggage, which leads you to start thinking that "any sort of movement within this 4D space is possible". Nothing in relativity shows that freely moving back and forward in the time dimension is possible. The closest semblance is slowing your own time relative to other things you care about, so that, for example, you can have the body of a 30yr-old while earth is at 3000AD, but again that's not "traveling" around time, it's closer to putting food in the fridge so it spoils slower.

</comment></comment></comment></comment></comment></comment></comment><comment><USER15> To me it wasn't completely clear.

\+ A discrete, infinite Hilbert space, with (wave) functions defined at each point. Why discrete?

\+ An operator across this Hilbert space that describes the evoltion of the universe.

\+ A non-recurring property of the overall system that depends on the infinity of the system.

\- Question. If the system is really big, can we see if it is recurrent or not?

\- Question. Deviations from equilibrium should be "minor". However, minor deviations on a very fundamental level (of quantumgravity) might perhaps result in genesis/destruction of complete universes. If there is some kind of process that goes to low entropy can it be self-inforcing till it big bangs?

\- Question. If time is a parameter for the universe's walk in Hilbert space, why is it real?

</comment><comment><USER16> I take the endofunction view. plank :: u -> u

Assume u is finite. Then we are either losing information or stuck in an infinite loop.

</comment><comment><USER17> Another interesting thought experiment: what if time (rather entropy) is the _only_ thing that exists? While highly likely to be untrue, it's an interesting mode of thought: as matter dominated beings we naturally approach conclusions from the perspective of matter.

<comment><USER18> You could also ask, what if time is the primary thing that exists? That is, it has authority over everything else that exists. This would mean that the laws of physics, for example, could change over time.

</comment></comment><comment><USER19> Those who say we live in simulation, are they saying that there is a creator(s)?

<comment><USER20> Yes. Except that we're probably not their chosen people, just one of the experiments.

<comment><USER21> One of my pet hypotheses is that the universe is so vast, that god doesn't have the slightest clue that we're here.

</comment></comment></comment><comment><USER22> Time exists. It's the observed difference between two states.

Also, i am not a physicist.

<comment><USER23> Exactly; it's the measurement of change. As long as things are changing, time exists. (The fact that this discussion is taking place proves it's existence!)

<comment><USER24> > As long as things are changing, time exists.

Except at the speed of light.

<comment><USER9> Which by definition is impossible to reach.

<comment><USER25> Photons reach it all the time. Therefore, time does not exist for photons.

</comment></comment></comment></comment></comment><comment><USER26> Then conservation laws would not hold.)

<comment><USER27> Exactly!!! To me this is the obvious consequence. Another thing is Fermat's principle, if time doesn't exist then what is light minimizing as it moves through space?

<comment><USER28> Aren't you showing necessity? If you transition from state A -> B , then X must hold. Where X is conservation of energy, charge, etc... It doesn't say anything about how long it takes to get from state A to state B. Or time existing per se, rather some relations that must hold between states. They don't actually have to hold, but you don't live in those invalid states. Similar to constructive light perhaps.

I remember the old boost mode on PCs where you could run your game 2x as fast by increasing the CPU clock speed (increasing game transitions relative to brain transitions), and yet the rules of the game still hold despite the game transitioning faster. Also making very hard to see/play (No turbo boost for the brain :)

</comment></comment></comment><comment><USER29> Any recommended books on this topic?

<comment><USER30> Chemistry nobel Ilya Prigogine has defended the idea beautifully in his books embedding the hard science in a wider humanistic context, including biology, ecology, urbanism, societal, entomology and other examples. He kindled my interest in dynamics and makes a huge effort to be understandable.

</comment></comment><comment><USER18> Check out Henri Bergson. The first person to argue that Time is Real.

<comment><USER31> He had a public debate with Albert Einstein about the nature of time and lost badly. Never fully recovered.

</comment></comment><comment><USER32> Title needs a (2008).

<comment><USER33> Or does it?

<comment><USER34> It depends on the arrow of time.

<comment><USER35> Title needs a (2028)?

</comment></comment></comment></comment><comment><USER36> I'll leave it here:

[https://youtu.be/v99-S4_IvVg](https://youtu.be/v99-S4_IvVg)

<comment><USER37> Save me some Googling and time, is this a documentary with information or is it a bunch of people with doctorates in angel therapy like What the bleep do we know?

<comment><USER14> It is part of an excellent PBS documentary by Brian Greene - the Fabric of Cosmos. It discusses Newtonian View, Relativity revolution, etc. Though it doesn't go to the depth of quantum cosmology levels as in the parent post.</comment></comment></comment>


Whatfactors determine price of crypto currency? - <AUTHOR> Lately we have witnessed a lot of hike in Bitcoins. There are other crypto currencies too which are competing in this race. So what exactly fuels these currencies, what are the factors which  decides the price of these currencies? <comment><USER2> Fear and Greed.

</comment><comment><USER3> We have published an article that generally explains the pricing equation of a Bitcoin. Take a look: [https://blog.cryptopay.me/who-really-affects-bitcoin- exchang...](https://blog.cryptopay.me/who-really-affects-bitcoin-exchange- rate/)</comment>


Publishing with GitHub Pages, now as easy as 1, 2, 3 - happy-go-lucky https://github.com/blog/2289-publishing-with-github-pages-now-as-easy-as-1-2-3 <comment><AUTHOR> How the hell do I upload or even make subdirectories? I do not understand.

[https://github.com/timonoko](https://github.com/timonoko)

<comment><AUTHOR> I found the answer by myself: You can "drag" a directory, but you can not "select" one. Thus this is not some novel github feature, but a quite obvious bug.</comment></comment>


You don't need a technical co-founder - <AUTHOR> https://medium.com/@collinsmalcolm/why-you-may-not-need-or-want-a-technical-co-founder-1732a6d05752

<comment><USER2> I'm working on a site where we follow this philosophy, and it works great but we have to design our features around the plugins available and how they've been implemented. Yes there are lots of plugins, but some of them are _very_ dodgy and buggy.

For an MVP, you're spot on. But as soon as you've got the money and traction, move it onto a platform that you control using people that you pay. Bonus is that you have an excellent wireframe to work from :)</comment>


Energy Recycling Phones - <AUTHOR> http://newsroom.ucla.edu/portal/ucla/ucla-engineers-invent-photovoltaic-210685.aspx

<comment><USER2> Here's the same story from a week ago, with some discussion:

<http://news.ycombinator.com/item?id=2871501>

The same story from another source was also posted the next day here:

<http://news.ycombinator.com/item?id=2875094></comment>


Linux Sucks - <AUTHOR> https://lunduke.com/posts/2020-05-28/ <comment><USER2> [https://news.ycombinator.com/item?id=23346567](https://news.ycombinator.com/item?id=23346567)

</comment><comment><USER3> There are two kinds of things: the ones that suck and the ones nobody cares about.

<comment><USER4> There are two kinds of "X Sucks" articles: those from haters and those from fans. The former are boring, the latter are interesting.</comment></comment>


Free porn websites could be shut down within months, says David Cameron - <AUTHOR> http://www.independent.co.uk/life-style/gadgets-and-tech/news/free-porn-websites-could-be-shut-down-within-months-says-david-cameron-10429552.html

<comment><USER2> > "David Cameron could force porn websites to shut down"

Could he? Really? I doubt it.

</comment><comment><USER3> Business idea: external age-verification service for these sites to use. Single-login that replaces the "please click on the over-18 button" landing page, with age verification probably done via entering a credit card.

<comment><USER4> There are already many of those services. But many of those who are even trying to be serious just ask for a credit card to verify that you're of age. Not sure how else to check if someone is of age without massive privacy issues, especially since the 'potential' customer could just lie.

</comment></comment><comment><USER5> Confirming age would require sites to identify users, which is a non-starter. The sites would lose all their traffic from much larger markets than the UK.</comment>


Apple acquired mind-blowing 3D mapping company C3 Technologies - <AUTHOR> http://9to5mac.com/2011/10/29/apple-acquired-mind-blowing-3d-mapping-company-c3-technologies-looking-to-take-ios-maps-to-the-next-level/?utm_source=feedburner&utm_medium=twitter&utm_campaign=Feed%3A+9To5Mac-MacAllDay+%289+to+5+Mac+-+Apple+Intelligence%29 <comment><USER2> I currently work for Yell Labs in the UK (though quit last week to fully commit to the startup I'm working on with 2 other great guys), and we use C3 on the maps part of the main website.

If you want to see what it looks like, try this: <http://www.yell.com/map/>

Only a few locations in the UK were commissioned... the cost is high so we aimed at the large cities to start with. It's really good stuff so long as you stay away from trees that are near buildings ;)

The dataset is enormous though. Going to be interesting to see that go mobile.

C3 basically took a FPS game map approach (poly data and textures) and overlaid that with a tiled map approach. So each tile downloads the poly and then lays the texture for that tile over the poly.

<comment><USER3> My question to you, sir, is how did you manage to get such a domain name for a seemingly bootstrapped company? Kudos!

<comment><USER4> Amusing indictment of the UK's longest-established [1] directory service that they look "seemingly bootstrapped" at a glance.

[1] Yellow Pages started 1954 in the UK

<comment><USER2> It's even older, it belonged to the GPO (General Post Office) before that, which is why it is yellow... the post office was yellow before it obtained the royal charter, renamed and rebranded.

</comment></comment></comment></comment><comment><USER5> The company is headquartered where I live, Linköping in Sweden with 150 000 people. They were spun off from fighter plane manufacturer Saab Aerospace which is also situated in Linköping. Saab owned 53% of the company and Apple paid around $250 millon.

EDIT: Here is a video from Saab showing the process of acquiring map data and it's military applications: <http://www.youtube.com/watch?v=CNemPTHOKWg>

<comment><USER6> That must be why the second video is of "Oslo, Sweden". :)

Tjena, Martin, förresten. :)

<comment><USER7> I also figured that :) Kul att se fler Svenskar på HN!

</comment></comment></comment><comment><USER8> My first thought after seeing the videos is how this will apply to video games.

It seems like a relatively easy way to replicate the real world into a game map.

</comment><comment><USER9> Interesting. Previously, the same company has been behind the 3D view of Nokia's map service <http://maps.nokia.com/3D/> — more info e.g. here [http://www.ubergizmo.com/2011/04/c3-technologies-behind- noki...](http://www.ubergizmo.com/2011/04/c3-technologies-behind-nokias-ovi- maps-3d/)

</comment><comment><USER10> How is it different from this? WebGL 3D maps. <http://maps3d.svc.nokia.com/webgl/>

Edit: Of course they will do it Apple way, which means excellent execution and integration.

<comment><USER11> It's not different at all since Nokia is using C3's techology.

[http://www.businesswire.com/news/home/20110419007396/en/C3-T...](http://www.businesswire.com/news/home/20110419007396/en/C3-Technologies-3D-Cities- Part-Nokia-Ovi)

</comment></comment><comment><USER12> I remember these guys being at Where 2.0 a few years ago. They were not hiding their desire to be acquired very well at that point: they were almost begging to get every Google employee present into their exhibit booth. Interesting to see they finally got a bite from Apple.

</comment><comment><USER13> Reminds me of <http://hitta.se/3d> \- zoom to Stockholm.

[edit: its their work as well]

<comment><USER14> Yeah, I was wondering if this was the same technology that hitta.se has been using for years.

</comment></comment><comment><USER15> wow, that looks cool. But the whole world has to be 3D, wanna see the Himalaya and rain forests and my home town in 3D :-D

</comment><comment><USER16> And still no turn by turn directions :p

<comment><USER17> This is actually a fairly serious issue for all non-Android handsets, IMO.

The built-in integrated-into-almost-everything Google Nav functionality is the killer feature that trumps all other killer features in phones for me. Obviously YMMV and for some people this feature isn't as big a deal, but it is a huge deal for me and it is what stops me from seriously considering anything that isn't an Android phone these days.

For the record, I do realize there are quite a few GPS turn by turn solutions for the iPhone, but suggesting they are a true replacement for Google's Nav stuff is like suggesting Google Voice Search is a replacement for Siri.

<comment><USER18> I use Tom-Tom in the iPhone and it is good. The most incredible thing is that if I make a wrong turn it recalculates new directions. I knew this existed in classic GPS devices but never realized how useful it was until I actually used it. Plus it does not require a signal which is actually really useful when you travel to Canada (from the USA) where you cannot use the local telephone service unless you are ready to pay a lot of money.

I think iPhone with Tom-Tom is fine. It costs $60 dollars but you can share it with 4 other devices which means you can spread the cost.

<comment><USER17> You just did that thing which I tried to prevent anyone from doing with my last paragraph.

Sorry but the GPS solutions on the iPhone just aren't the same (btw, direction recalculation is a no brainer and of course Google Nav does that, and a whole lot more like local data polling from other Google Nav users to determine realtime road speeds for path redirection)

Anyway, it is the full OS integration that is key. Basically anything on the phone that displays an address (web browser, Google Maps, apps like Yelp, etc) displays it as a clickable link letting me instantly pull up directions and switch into nav mode. This sort of integration is huge but sadly the sort of thing people tend to gloss over unless they've actually experienced it, which is why I tried to preempt that with the (also flawed) comparison between Google Voice Search and Siri.

<comment><USER19> _> Basically anything on the phone that displays an address (web browser, Google Maps, apps like Yelp, etc) displays it as a clickable link letting me instantly pull up directions and switch into nav mode._

This is in iOS too. Of course you don't get turn-by-turn, just directions, but if Apple is eventually going to add turn by turn you'll find it there.

</comment></comment></comment></comment></comment><comment><USER20> had to add "mind blowing " or it wouldnt be worth it uh

<comment><USER21> cliche headlines make me want to run too ... I despise them.</comment></comment>


Tomorrow's World - Home Computer Terminal (1967) - <AUTHOR> http://www.youtube.com/watch?v=aJ6SbvrjxZA

<comment><USER2> What I like better of Tomorrow's World is the mobile phone (1979):

[http://www.youtube.com/watch?v=vix6TMnj9vY&feature=chann...](http://www.youtube.com/watch?v=vix6TMnj9vY&feature=channel)

</comment><comment><USER3> Wow, I have never seen this: human digital logic.

<http://www.youtube.com/watch?v=f1DtY42xEOI>

Kids acting as bits in a machine register and performing binary arithmetic by raising their hands if set, or not raising when cleared.

Really cute.</comment>


Ask HN: What would you have Conficker do? - <AUTHOR>

Being that today is April 1st - April fools day - and also the day Conficker computer virus was to download a new set of instructions. I was thinking what would I do with the 3-12 million computers at my beck and call.
Email resignation letters to everyone's boss. Insert Porn into everyone's PowerPoint slides
Pretty lame that's why I asked the question. <comment><USER2> Update all the people with ie6 to something newer

<comment><AUTHOR> Now that you mention it, I can't think of anything better for humanity.

<comment><USER3> You have a very limited imagination.

<comment><USER4> I don't think that Conficker is going to be making an impact on world hunger very soon.

</comment></comment></comment></comment><comment><USER5> Synchronize the system clock, set the volume to maximum, and then, at the right moment, and with perfect synchronicity, each computer would play back a prerecorded speech claiming to be a message from God...

<comment><USER6> Or Rick Astley.

<comment><USER7> Same thing no?

</comment></comment></comment><comment><USER3> Calculate the quintillionth bit of Pi. With ten million reasonably modern computers it shouldn't take more than 12-24 hours.

<comment><USER8> To those who might have missed what the parent is talking about, in 1995 a formula was discovered that lets you calculate the n'th bit of pi without calculating the previous n-1 bits. This surprised everyone.

The consequence is that you can compute the n'th bit in essentially linear time, and essentially constant memory. By traditional methods, computing the quintillionth bit would be unthinkable.

However, I doesn't look like the algorithm is parallelizable in a meaningful way. Any thoughts?

<http://en.wikipedia.org/wiki/Bailey–Borwein–Plouffe_formula>

<comment><USER3> The BBP algorithm is not only parallelizable, it's embarrassingly parallel. Each term in the series can be computed independently of the rest.

In case you missed half of the joke: The PiHex project computed the quadrillionth bit of Pi back in 1998-2000... and was run by yours truly.

<comment><USER8> I sure did. Funny thing is, I was into this stuff back then (at one point me and another guy were chasing the record for the largest 7-tuple in arithmetic progression; we ended up with the second largest), so I'm sure I heard about your effort at the time. BBP survives in my memory a decade later, but not PiHex.

I have to say though, your original comment was definitely an obscure reference, even on HN :-)

<comment><USER3> _I have to say though, your original comment was definitely an obscure reference, even on HN_

I think a lot of people who have been here for longer than you were aware of my connection to PiHex -- it has come up a few times.

<comment><USER9> Not all of us keep our leather bound "Life and Times of Colin Percival" on our desks.

Some of us keep them under our pillows so we can have sweet, sweet cperciva dreams.

</comment></comment></comment></comment></comment></comment><comment><USER10> Seed torrents.

Hey, if everyone's upstream bandwidth is being soaked up by _The Wire_, other viruses won't be able to use it to send out spam.

<comment><USER11> Up-modded simply because of all things in the world you chose to seed _The Wire_. <3

</comment></comment><comment><USER12> Put up fake april fool's day websites in place of popular sites. Oh, wait... nevermind.

</comment><comment><USER13> Folding@home. Or other peoples homes.

</comment><comment><USER14> Downvote non-HN type stories at HN.

</comment><comment><USER15> Crack the encryption on someone's DomainKeys implementation so that I can sign mail as coming from them. Then successfully spam the world.

<comment><USER16> Domainkeys/DKIM for IIS/news

</comment></comment><comment><USER17> Skynet. Self-awareness is only a few million more bots away...

</comment><comment><USER18> With apologies to Nate Lawson: delete any website, blog post, message board, or email thread that talks about Conficker.

<comment><USER19> the first rule of conficker...

<comment><USER20> ...is also the second rule of conficker

</comment></comment></comment><comment><USER21> Place billions of orders to small breweries around the world and have them shipped a select few small towns.

</comment><comment><USER22> 1-setup the biggest cloudcomputing host.

2-profit.

</comment><comment><USER23> fix the economy :)

<comment><USER24> Was thinking along those lines. Start transferring money from all accounts to all accounts. Stop when everyone has the same amount of money. Should be fun for a while.

<comment><USER21> How much would everyone have if that happened?

My guess is somewhere around $50k.

<comment><USER25> Depends on if you mean M0, M1, M2, or M3.

If you mean M0, then assuming 300,000,000 people in the US it's $2,500 per person. If you mean M2 it's $25,000. And M3 is is a secret, but in 2006 it was about 35% larger than M2.

Defining money is a lot more complicated than you think, since the majority of the money in the world is in the form of debt, and it's not actually possible to share it around.

<comment><USER21> good point. I was doing a simple "how many 'dollars' are in 'circulation' / population". of course, most money isn't money, it is, like you said, digitized debt.</comment></comment></comment></comment></comment>


Ask HN: Should I quit my job (or work part-time) to join an Uber for X startup - <AUTHOR> A former colleague has founded an Uber for X startup. They want me to join without salary to build their software from scratch. After having worked there for free for a almost year (or even longer if I don't work full time) I would get stocks worth the salary I never got, to become co-owner.<p>Do you think this a good deal to consider? I think becoming stake in an Uber for X business sounds like fun but I am afraid I can't get by on savings and I would lose most of my current job security and salary. Risk/reward, opportunity cost? I'm really hesitant to work for free in return for stocks... <comment><USER2> Heck no.

I'm going to ignore the whole "working for free" question for a second, and how you will almost certainly never be compensated.

The issue I take with this is: If you're working for free then stock should be given to you from day #1, not suddenly given to you in a lump sum after a year. The way you describe this, the owner can fire you after 364 days, and you aren't entitled to stock or financial compensation. And frankly, some of the people I've met in the startup world are sociopaths and will happily fire someone after 364 to keep a large % stakehold in their company, then will rationalise it, and sleep like a baby.

Now taking stock over a salary is a bad idea in general as stock in startups rarely pays out. And if you're taking stocks in lieu of salary they should be worth MORE than salary given the levels of risk and the relative values to you (stock is worthless even for years after you receive it). Plus stock's value is subjective anyway, are they going to get a valuation by an independant organisation, or just declare the company's value arbitrarily?

Honestly the whole thing sounds like a great deal for them, and a terrible deal for you.

You better be best buddies with this guy to consider this since trust is key here. If they're taking a salary then run away. I'd also re-negotiate so some stock is given earlier so less lump-summing occurs.

</comment><comment><USER3> Startups are great - you get a ton of ownership and the chance to see a business grow. Even if it fails it'll be a huge educational experience.

However, this sounds fishy for a couple of reasons - but maybe the guy just doesn't know how to structure this.

With one year vesting, he wants to protect himself from the scenario where you work for 3 months and own a big chunk of the company. That's legitimate. However, get the amount of equity on paper. You are taking a risk here too so it should be far in excess of just covering your salary at an arbitrary valuation. The general advice is that if you are not getting paid, you are a founder - your equity take should be a double digit percent of the company (typically vesting over 4 years with a 1 year cliff).

The other thing to consider is what he is bringing to the table. If it's just the idea of Uber for X it's not worth much. If he has business contacts though - for example he's well connected to the industry X then maybe he's bringing a lot more.

Don't be a sucker though, and don't work for free or for vague promises. Get agreements on paper now. And don't undersell yourself.

<comment><AUTHOR> He has very good industry connections but I'm still very hesitant and think I'll say no.

Thanks for your great comment!

</comment></comment><comment><USER4> Don't listen to the naysayers! This is a good learning opportunity. For example, you'll learn why you shouldn't spend a year (or more) working for free on a former colleague's Uber for X startup.

</comment><comment><USER5> Absolutely not. Creating an Uber for X startup and working for free are two of the worst ideas I've ever heard.

</comment><comment><USER6> It sounds as though the company has no product, no traction, and no investment. So, to work for stock alone you should insist on being an equal co-founder -- especially if you are crucial to building the software and taking on identical risk. If he claims you are a co-founder, he should also share the cap table with you for verification and to show he trusts you as a co-founder.

<comment><AUTHOR> The company has drivers and a shop which will do all online orders via them. They will also be featured in magazines promoting their business.

They have no investment because they want to increase value by doing first and then scale up via investment. Is this called bootstrapping?

I'm not sure if I want to be a co-founder with an equal share since that would force me to go all in on the business idea.

I am interested in the idea of working close to self-employed and create new services which can grow. It's just the "no-salary until date X" deal I'm unsure about. I'm thinking about suggesting some alternative contract offer.

<comment><USER7> You can be a co-funder, a two digits equity and not be involved in the commercial part of the business. (But you must trust the other co-founders.) Just imagine that you get a fancy title like CTO :).

Also, get everything in writing before starting to work: "Oral contracts are not worth the paper they are written on."

</comment></comment></comment><comment><USER8> If you're working for free to build something that's starting out, then you should have an equal share of the business to the other founders, with same break clauses they have.

</comment><comment><USER9> In the US, working for free is illegal and hence a minefield when the company goes to attract outside investment. If that weren't enough, everyone should be on a multi-year vesting schedule including the founder [you work for a year, get 20,000,000 shares and the founder stops working, and then what?] Finally, the stocks are only worth your salary if you can sell them, but who will buy them at face value? If the company can buy them, then they can pay your salary.

To put it another way, if you're going to work for a year for no salary, and you are capable of building the software for an Uber for X from scratch, why not just build your own Uber for Y? And to put it a third way, suppose your former colleague was asking you to give him the next year's worth of paychecks from your current job in exchange for equity a year from now. Would that be a good deal to consider?

Good luck.

<comment><AUTHOR> Great input!

I have called and declined the offer.

</comment></comment><comment><AUTHOR> He hasn't presented the offer to me yet. Just wanted to know if I was interested in joining them. The offer might be that I would get stocks immediately but no salary until after so many months. He hasn't accepted any investments yet to build the software and add value before sharing ownership.

But I'm on you people's side that I don't want to work for free. Just wanted to hear pros and cons on joining a startup and defer a potential reward. I've long wanted to do something of my own that I feel passionate about instead and get investors aboard early enough that I can get salary.

</comment><comment><USER10> 1- get the stock first 2- then only work...

If your former colleague wants you onboard, let him make you co owner first.

</comment><comment><USER11> If you are going to build it for free, why do you need him? Just build it yourself.

<comment><AUTHOR> He has customers and drivers but cannot scale without a system.

</comment></comment><comment><USER12> Work for free! Sounds like a great way to earn a living.</comment>


Gcam, the computational photography project that powers the Google Pixel camera - <AUTHOR> https://blog.x.company/meet-gcam-the-x-graduate-that-gave-us-a-whole-new-point-of-view-3ee86657d6c9#.epxa2b2rq <comment><USER2> > So the team started to ask — what if we looked at this problem in an > entirely new way? What if, instead of trying to solve it with better > hardware, we could do it with smart software choices instead?

I feel like the lofty language takes something away from the article. It's not like using software to improve image quality is anything new. The image stacking technique they describe isn't particularly novel. I've done stuff like that for years. It even works on 3d renderings from a path tracer. Its cool their camera is fast and provides a nice ux when stacking images, but that's only possible because of the cameras hardware.

<comment><USER3> Agreed. I think my last 5 smartphones have all had an HDR mode. Claiming it is something new is a little strange.

Even HTC's relatively new technique of recording a couple seconds of continuous video as long as the camera app is open so it can provide an "instant" shutter button is years old at this point and that came out long after HDR in smartphone apps.

<comment><USER4> It's not the same as "normal" HDR:

[https://research.googleblog.com/2014/10/hdr-low-light-and- hi...](https://research.googleblog.com/2014/10/hdr-low-light-and-high-dynamic- range.html)

<comment><USER5> That article describes exactly how "normal HDR" is achieved with a DSLR.

<comment><USER6> I don't think "normal HDR" traditionally includes this:

"HDR+ addresses [low-light blur/noise] by taking a burst of shots with short exposure times, aligning them algorithmically, and replacing each pixel with the average color at that position across all the shots. Averaging multiple shots reduces noise, and using short exposures reduces blur."

<comment><USER7> Reducing shutter speed to reduce blur isn't new ([https://www.dpreview.com/articles/1528656007/notimagestabili...](https://www.dpreview.com/articles/1528656007/notimagestabilization)), accumulating sensor exposure is how DSLRs work, and aligning frames is how image stabilization works. It might not be what we call "HDR", but there's nothing new here. The combination in a phone camera sounds nice.

</comment></comment></comment></comment></comment></comment><comment><USER8> Sigh. I'm disappointed that this piece seemingly gives no credit to Andrew Adams, Jiawen (Kevin) Chen, and all the folks that made gcam happen. There isn't even a mention of Halide...

Edit: just to be clear, I like Marc just fine, but I don't see the point in excluding the team.

Disclosure: I work at Google and know the folks involved.

<comment><USER9> It's a desperate attempt to make X look good. There haven't been too many successful "graduations".

<comment><USER10> What rate of success would you consider acceptable? I thought the whole point of Google X was basically "let's throw stuff at the wall to see what sticks", so it seems pretty much expected that not a lot of products would make it out of the lab before being killed.

</comment></comment></comment><comment><USER11> Surprised by Negative Tone of Comments.

I have been using PixelXL since launch and every one of my friends who looked at photos are amazed by the camera (Many of iPhone Users). PixelXL made me default photographer at parties (And fact that I can share Photos using Google Photos with everyone at Party).

Pixel Camera is amazing compared to any existing SmartPhone camera.

Side Note: The only issue I have with Pixel is that its easy to break glass.

<comment><USER12> I've had the same reaction, but with an HTC 10. I'm curious now what a side- by-side between the two would look. The 10 uses a really novel lens with OIS and HDR, whereas the Pixel has no OIS but uses fancy EIS.

I'm actually surprised how little love the 10 gets, considering the noise made around the hardware quality of the Pixel, and the fact that HTC made both. I guess people just like the Google brand or something.

<comment><USER13> Seems like the HTC 10 really isn't all that great.

"The real surprise from these tests isn't the winners, though — it's how bad the losers are. In some situations, the LG, HTC and Sony phones put out pictures that loom downright unusable, something I'd expect more from a 2013 Moto G than "

[http://bgr.com/2016/12/14/iphone-7-camera-vs-google-pixel- ga...](http://bgr.com/2016/12/14/iphone-7-camera-vs-google-pixel- galaxy-s7-htc-10-dslr/amp/)

<comment><USER12> Well that's just a reference to [http://www.techradar.com/news/how-2016s-best- camera-phones-c...](http://www.techradar.com/news/how-2016s-best-camera- phones-compare-to-a-dslr)

It looks like they had smudges on the camera lens. I've taken much more challenging shots than that without the horrible blur they have. But smudge any smartphone lens with fingerprints and it will look like that. Hell, smudge a DSLR lens and it will look like that too.

</comment></comment></comment></comment><comment><USER14> This blog post is remarkably light on details. For the actual research paper behind the software in the Pixel camera app: [http://www.hdrplusdata.org/hdrplus.pdf](http://www.hdrplusdata.org/hdrplus.pdf)

</comment><comment><USER15> Surely many of these improvements are simply due to the Sony Exmor sensor? HDR processing is only really possible when you have fast (and full resolution) burst mode available on the sensor.

<comment><USER6> Given the relatively long timeframe of the project, we don't know if that was an idea/requirement from the gcam side.

</comment></comment><comment><USER16> > One direction that we're pushing is machine learning

Is machine learning the answer to everything these days? Is it over-hyped...or should I start worrying that I don't know anything about it (as a developer I mean).

<comment><USER17> The limits of ML (as we know it) is still not fully known, so it's worth throwing a wide range of problems at it to see what sticks. I think that's why you see talk of ML everywhere, because people are still feeling out the space, seeing how far ML can go. Eventually, the dust will settle and the next big thing will come along.

<comment><USER18> So yes, should start worrying?

</comment></comment></comment><comment><USER19> Had an interesting/cool moment with my Pixel at the theatre today. There was a line to get your picture taken in front of the show's giant poster. The attendant would take your phone and snap a pic.

When the attendant used my phone, she couldn't tell it took a picture -- because when you press the button it's _instant_. She was so used to other phones taking a second or two before a picture was taken.

<comment><USER20> Just tried on my iPhone 7, it's definitely instant. Perhaps that's more of a UI feedback flaw in the Pixel then?

</comment></comment><comment><USER21> Article does not deliver on the headline (of course). It says that X wrote software that became HDR+ , Google's version of HDR.

<comment><AUTHOR> Please > Most recently, Gcam's HDR+ technology launched as the default mode for the critically acclaimed Google Pixel phone. DxOMark, the industry standard for camera ratings, declared that the Pixel camera was "the best smartphone camera ever made" in 2016. Reflecting on the evolution of the project, Marc says, "It took five years to get it really right…and we're grateful that X gave our team the long-term horizons and independence to make that happen."

</comment></comment><comment><USER22> There's a lot of pressure on smartphone makers to make really good image processing software because they are extremely restricted hardware wise -- there's just no space for a proper lens and a big chip. And it's amazing how far they've gotten in the past few years. Phones are now better cameras than most point-and-shoots.

I wonder if there's any chance that some of that amazing software makes it's ways to pro cameras? It seems that camera companies can't keep up.

For example, the autofocus and whitebalance on my phone is almost always spot- on and perfect. My 'real' camera (a Fujifilm X100T) often gets the focus wrong, and the automatic white-balance is not as reliable. It seems like camera makers just can't keep up on the software side.

</comment><comment><USER23> [Heh, the cynic in me is amused when these things come out on the heel of a lot of bad news about Google.]

I think computational photography is perhaps the biggest change to picture taking since Ektachrome. Seriously it takes pictures with existing hardware that are better pictures and does it by applying some interesting science to the mechanisms in the pipeline. I've been very impressed with the results and how rapidly the camera comes up with the image after taking it. I wish my Canon SLR had this as part of its software load.

<comment><USER24> What's the 'lot of bad news'? I couldn't find anything on HN search recently, except discontinuation of Google talk. Perhaps you confused Google with Uber?

<comment><USER23> Several articles covering advertisers pulling ads from Youtube[1,2,3] because Google runs them next to objectionable content, a 4% drop in Google's share price [4,5]

[1] [http://www.theverge.com/2017/3/22/15029214/att-verizon- googl...](http://www.theverge.com/2017/3/22/15029214/att-verizon-google- youtube-pull-ads-boycott-hate-speech)

[2] [https://www.theguardian.com/media/2017/mar/17/google- pledges...](https://www.theguardian.com/media/2017/mar/17/google-pledges-more- control-for-brands-over-ad-placement)

[3] [https://arstechnica.com/business/2017/03/big-us-companies- pu...](https://arstechnica.com/business/2017/03/big-us-companies-pull-youtube- ads-after-extremist-content-sparks-uncertainty/)

[4] [http://www.cnbc.com/2017/03/20/google-stock-downgraded-to- ho...](http://www.cnbc.com/2017/03/20/google-stock-downgraded-to-hold-on-ad- fears.html)

[5] [https://www.recode.net/2017/1/26/14402080/alphabet-google- ea...](https://www.recode.net/2017/1/26/14402080/alphabet-google- earnings-q4-2016)

</comment></comment></comment><comment><USER25> Marc Levoy (who the article is about) gave a lecture series [1] at Google about digital photography.

[1] [https://www.youtube.com/playlist?list=PL7ddpXYvFXspUN0N-gObF...](https://www.youtube.com/playlist?list=PL7ddpXYvFXspUN0N-gObF1GXoCA- DA-7i)

</comment><comment><USER26> I like how they have taken credit for implementing HDR along with a smartphone-sized burst camera.

This is purely a technical implementation and is not novel in almost any way.

<comment><USER27> I agree that this article was thoroughly disappointing. I went in expecting a lot and received VERY little information.

</comment></comment><comment><USER28> Lots of PR-ish tone here. Image fusion is pretty standard in video cameras, it's part of the imaging pipeline. The IP on that dates back 15-20 years.

</comment><comment><USER29> It's a step in the right direction for mobile photography but not really revolutionary. Exposure fusion and pixel alignment has been around for a long time.

Would like to see more options for tonemapping (really like ACR's highlight/shadow recovery), higher dynamic range sensors and most of all 10bit or raw video on mobile phones.

Halide is great btw

</comment><comment><USER30> Ok, since maybe Google people will be looking at this:

I have a Nexus 5x. The Google camera app recently, finally, received a revision that fixed some significant bugs, e.g. crashing on "zoom out".

It also introduced ISO offset/adjustment. However, the widget to make that adjustment appears only briefly, at the top of the screen, immediately after touching the screen -- to set a metering point or to zoom. This makes that control both difficult to trigger, at the top of the screen, and difficult to use with its small scale and position that leaves one's finger obscuring the readout. On my 5x with a Pleson glass screen protector, the resulting value also tends to jump a bit as my finger is removed (1). Finally, the setting only remains for a matter of seconds, until the app clears any custom (i.e. via touch point) metering setting (2).

I like to adjust the ISO offset setting until I get the exposure I'm after on the screen. I wish the control was easier and always available to trigger, easier to use, and that the value set would persist at least until the shot is taken and preferably, or optionally, until it is manually changed back.

You finally gave me ISO offset control -- thank you! But the control is difficult to the point where I mostly don't even try to use it.

The app update also introduced a widget along the right side that displays an ungradated meter of (digital) zoom level. Beyond seeing the relative zoom setting, this control doesn't really do much that I find useful. (Actually, sometimes I find myself waiting for it to clear so that I can see my composition better.)

That widget position on the right side would be the perfect place to optionally display a touchable ISO offset scale. More real estate, making fine adjustments easier. Finger not in the way of seeing both the values and the shot, while adjusting it.

If not by default, then maybe something that could be selected in the options?

Friends really like my photos from the Nexus 5x. I'd love to have more-better controls when composing them. Thanks.

\--

1\. My zoom level can similarly jump a bit when I lift my fingers from the screen. I assume this is because of the screen protector, as opposed to the underlying phone/app, and have come to live with it as the price for the screen protection. The jump in ISO offset, maybe because of the small size of its widget as well as its placement, is harder to control.

2\. This momentary clearing was already happening before the app update. I like to take my time composing my shot, and this clearing already made doing so somewhat frustrating at times.

</comment><comment><USER10> So it's just the same HDR+ they've been using in Nexus devices for a long time now? They didn't do anything special with the Pixel's camera, specifically?

</comment><comment><USER31> Sorry to hijack the thread but I found your handle a bit disturbing.

What do you need help with?

<comment><USER32> He created his account 231 days ago. Whatever he needed help with presumably is no longer an issue.

<comment><USER27> It never hurts to ask. Maybe he's been waiting for this day for 231 days?

</comment></comment></comment><comment><USER33> The surprising part about this is that X decided to go with Medium as their publishing platform.

<comment><USER34> Let me continue: I specifically dislike how medium breaks urls.

<comment><USER35> I'm surprised Google wouldn't also use their own URL-breaking property, AMP. :)

<comment><USER34> Or their other url-breaking platform - blogger - who found out it was a good idea to redirect to a different top level domain based on visitor location :-/

</comment></comment></comment></comment><comment><USER36> WHO WROTE THIS?

\--

CATHOLIC

<comment><USER37> We've banned this account for breaking the HN guidelines. If you decide you don't want to be banned, you're welcome to email email@example.com and promise to follow the rules in the future.</comment></comment>


Arduboy: The Interactive Digital Business Card - <AUTHOR> http://bateske.com/arduboy/ <comment><USER2> I think there's a great opportunity for someone to release a simple, programmable Gameboy-esque device that runs Javascript or something similarly noob-friendly to give people (and kids) a less friction-filled path to learning programming. This might not be the device for that, but it's a really cool project nevertheless.

<comment><USER3> Javascript... what an odd choice. Definitely not my first choice for a language used to teach programming to beginners, nor to run on embedded systems.

ps: I'm well aware there are embedded systems for Javascript and it is being taught on codecademy to beginners, I'm just saying it seems weird to me.

<comment><USER4> The pros: It's RIGHT THERE. It's in your browser, complete with console and debugger. You don't need to download a compiler or interpreter or anything to play with it. You don't have to visit any particular site. All you need is Notepad or TextEdit.

It's about as close as you're going to come to this nowadays:

          **** COMMODORE 64 BASIC V2 ****
       64K RAM SYSTEM  38911 BASIC BYTES FREE
      READY.
      ◼

BASIC sucked in a lot of ways, but it was _right there_ , inviting you to play around.

<comment><USER5> C64 BASIC was all there was for many people, otherwise computers were mostly not affordable and available to children. There just wasn't real choice, so we used what we had. If structured BASIC or better had been shipped that would have been the thing to use instead, without a doubt.

Today there's a choice. We can't pretend we are forced. Now there are many MUCH better things. And if we intentionally choose hardware which enforces the use of something bad to start with, when we could put all kinds of things on all kinds of hardware today - it isn't because we were forced but because we are stupid. People with experience use Javascript because they have to in order to program the browser (due to a completely artificial monopoly) and they have the ability to adapt to it. Maybe they even develop stockholm syndrome and forget all the ways it's broken and missing basic capabilities. But that doesn't mean it's a good choice among starting languages when we have a free choice.

</comment></comment></comment></comment><comment><USER6> Why not just switch to KiCAD rather than use eagle? I have found KiCAD is far superior at this point and is open source. They mostly have the ability to use eagle libraries in KiCAD now (although it is in alpha I think).

Maybe they could donate the $820 to support KiCAD?

<comment><USER7> EAGLE is the tool they know. All their files are already in EAGLE's format, and even if KiCAD can "mostly" do import, that's not quite a matter of being able to pick up your design and keep on going.

In the electronics world, tool lock-in is a very real, strong, and painful force.

<comment><USER6> I don't have pity for people who choose to lock themselves in to tools and then ask for $800 because of it. Oh well, their choice! It really isn't much work to switch to KiCAD.

</comment></comment></comment><comment><USER8> Nice!</comment>


2010 List of Surprises and Predictions - <AUTHOR> http://www.blindreason.org/2010/01/2010-surprise-list.html

<comment><USER2> Interesting list and some of those look dead on...but no way Android gets as much traction as people thing.. I think Apple stays dominant.</comment>


Content Marketing - <AUTHOR> What are the benefits of content performance measurement metrics? I would appreciate the responses to the above question. Thanks in advance! <comment><USER2> Attend the below summit to get more insights on content performance measurement metrics from Content marketing experts. [http://qwardo.com/content-marketing-summit/](http://qwardo.com/content- marketing-summit/)</comment>


Computing prime factors with a quantum processor - <AUTHOR> http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys2385.html

<comment><AUTHOR> _Using a classical computer and the best-known classical algorithm, factoring something like RSA Laboratory's largest published number –– which contains over 600 decimal digits –– would take longer than the age of the universe, he continued....A quantum computer could reduce this wait time to a few tens of minutes._

\-- The synopsis, on why this is interesting, per UCSB PR

<http://www.physics.ucsb.edu/news/announcement/783-082112>

 _If such a processor enters the market, traditional encrypting will be forced to change completely. According to Lucero, the quantum processors power can be used for both sides of the process, allowing "quantum cryptography" to replace traditional RSA. Quantum encrypting would be more difficult to crack and far easier to keep secure — Lucero says quantum cryptography systems immediately notify both user and potential intruder when the system has been tampered with. For example, Lucero said a voice conversation over quantum encrypted lines would immediately become "jumbled" when a third party attempted to access the system._</comment>


A concise introduction to category theory - <AUTHOR> http://ncatlab.org/nlab/show/category+theory <comment><USER2> If you want an actual introduction to the topic, "Conceptual Mathematics: A First Introduction to Categories" by Lawvere and Schanuel is the right choice.

<comment><USER3> Funny coincidence, I just found this video [http://www.reddit.com/r/haskell/comments/1l4ph3/dsls_and_tow...](http://www.reddit.com/r/haskell/comments/1l4ph3/dsls_and_towers_of_abstraction_with_gershom/) back, where the speaker mentions many CT ideas (adjoint functors, galois connections) and end up pointing at abstract interpretation and Lawvere work.

</comment></comment><comment><USER4> This seems to be down right now [https://archive.today/vibrM](https://archive.today/vibrM) , however it's still available in google cache here [https://webcache.googleusercontent.com/search?q=cache:PKJbiW...](https://webcache.googleusercontent.com/search?q=cache:PKJbiWKTpScJ:ncatlab.org/nlab/show/category%2Btheory+&cd=1&hl=en&ct=clnk&gl=us) . Anyone know what's up?

<comment><USER5> nLab is often slow. It can't cope with its normal amount of traffic, so certainally not with front page HN.

</comment></comment><comment><USER6> Sure, it's concise, but I'd hardly describe ncatlab as introduction. It's more of a reference. I'd dare say the Wikipedia entry on category theory (and related links) makes a better introduction for the uninitiated.

To actually learn it, Mac Lane & Saunders "Categories for the Working Mathematician." seems to enjoy continued popularity.

<comment><USER7> MacLane is still the standard for working mathematicians, but for those with less background, Steve Awodey's book[1] is very good. He also has some YouTube lectures[2]. While you're on YouTube, the Catsters channel[3] has many excellent 10-minute category theory videos.

[1] [http://www.amazon.com/Category-Theory-Oxford-Logic- Guides/dp...](http://www.amazon.com/Category-Theory-Oxford-Logic- Guides/dp/0199237182)

[2][https://www.youtube.com/playlist?list=PLGCr8P_YncjVjwAxrifKg...](https://www.youtube.com/playlist?list=PLGCr8P_YncjVjwAxrifKgcQYtbZ3zuPlb)

[3][https://www.youtube.com/channel/UC5Y9H2KDRHZZTWZJtlH4VbA](https://www.youtube.com/channel/UC5Y9H2KDRHZZTWZJtlH4VbA)

<comment><USER8> I can second the Catsters channel. As a complete category theory newbie watching those videos was nevertheless enjoyable because of the upbeat and cheerful attitude with which the material was covered.

I actually found MacLane's book to be more approachable than Awodey's. Although I'm not sure this is good advice because it took me several years casually feeling my way through the field to start to gain an understanding into it (ie YMMV).

Interesting category theory historical fact! Checkout MacLane's wikipedia page and you will find one of his students was in fact Steve Awodey.

</comment></comment></comment><comment><USER9> Tom LaGatta in this video on Category Theory listed this website as number one resource on category theory.

[http://youtu.be/o6L6XeNdd_k?t=1h5m31s](http://youtu.be/o6L6XeNdd_k?t=1h5m31s)

There he also lists some books on category theory. I am putting a direct link when he mentions the references.

</comment><comment><USER10> Should we read this page as suggesting a prerequisite to learning category theory is being able to interpret LaTeX math mode on the fly?

Or did a bit of javascript magic not load for me?

<comment><AUTHOR> Something is wrong on your end, but it's not Javascript. It looks fine to me both with and without JS.

<comment><USER10> /Snark Thanks, tried it again and the images loaded. Must have been the alt- tags I was seeing. Much obliged.

<comment><AUTHOR> Actually, they're not images. They're MathML markup.

[http://www.w3.org/Math/](http://www.w3.org/Math/)</comment></comment></comment></comment>


Photographs of the abandoned Russian space shuttle - <AUTHOR> https://ralphmirebs.livejournal.com/219949.html

<comment><USER2> Man, these should be in a museum somewhere. What an amazing piece of history.

</comment><comment><USER3> Looks like, one day, everyone just decided to stop coming in to work. Eerie.

The story would benefit from a little editing. It's not necessary to publish _every_ picture taken. Many images are very similar.

Toward the end there are pictures of the inside of the shuttle itself.</comment>


New Research Shows Success Doesn't Make Women Less Likable - <AUTHOR> http://blogs.hbr.org/cs/2013/04/leaning_in_without_hesitation.html

<comment><AUTHOR> But I do agree with one of the commenters, who said that "women have to work to maintain likeability by walking the tightrope of the double bind. Women who are too masculine (which they must be to succeed) often are NOT liked. Those who are must be good at tightropes."</comment>