ICO of the day: Synthetic rhino horn erection pills, on the Blockchain - <AUTHOR> https://davidgerard.co.uk/blockchain/2017/09/04/ico-of-the-day-synthetic-rhino-horn-erection-pills-on-the-blockchain/ <comment><USER2> They need to work on their pitch, it's a bit thin at present. I suggest:

"If blockchain technology doesn't already get you hard, Synthorn will."

</comment><comment><USER3> This particular project doesn't inspire confidence, but I've been thinking for a while that it'd probably be good for rhinos if we could make convincing fake rhino horn powder and get it into the market.

<comment><AUTHOR> [author here] The article links several rhino conservation organisations pointing out why this is actually a bad idea - it would expand consumer demand for what is already an aspirational product, it would lend credibility to the completely fraudulent claims that rhino horn has any medical effect and it would provide cover for trade in poached horns. It _sounds_ plausible, but ...

<comment><USER3> I could see all that being a problem if you sold fake rhino horn as a legitimate product. "Here, have some synthetic rhino horn, almost as good as the real thing."

What I'm talking about is making fake rhino horn complete with DNA produced in machines, and selling it on the black market at a significantly lower price than poachers can manage. It'd basically have to be an undercover government operation.

<comment><AUTHOR> This already happens, per [https://www.savetherhino.org/rhino_info/thorny_issues/synthe...](https://www.savetherhino.org/rhino_info/thorny_issues/synthetic_rhino_horn_will_it_save_the_rhino) -

"* More than 90% of "rhino horns" in circulation are fake (mostly carved from buffalo horn or wood), but poaching rates continue to rise annually"

I urge you to read that in detail, it's a comprehensive response as to why Pembient are likely barking up completely the wrong tree, and variants on the idea are probably not good either.

<comment><USER3> Hmm I guess your quote might disprove my hypothesis.

In any case I completely agree that Pembient's idea is terrible, and we should not have any sort of legal variant of rhino horn on the market. My proposal was to produce illegal rhino horn powder that didn't happen to come from rhinos, while being much cheaper (assuming that's possible). It's academic anyway because it'd have to be a CIA operation or something similar, and it seems unlikely that the CIA would care about saving rhinos.

<comment><AUTHOR> I should note that Pembient have commented on the post making their case with several cites. (I still think the environmentalists' points are stronger, fwiw.)

</comment></comment></comment></comment></comment></comment><comment><USER4> I can't even tell if this is "real" or just fantastic performance art... Or even if there's a difference any more...

<comment><USER5> >Or even if there's a difference any more...

Very few performance artists drive a lambo.

<comment><USER6> I find that concept artists tend to have f-u money, whatever they drive.

<comment><USER7> And buying a lambo is one of the worst ways to spend a large chunk of f-u money that I can think of.

Unsubstantiated (yet difficult to disprove) assertion of the day: Lambo ownership is strongly correlated with being an asshole. Causal relationship currently unknown.

</comment></comment></comment></comment><comment><USER8> Add this to yesterday's Paris Hilton news and I'm pretty sure we've just spotted the top of the bubble.

<comment><USER9> Yes.[1] We're probably approaching the point where the SEC will do something to make ICOs do the same things IPOs are required to do. All they need is a good case. Look for "I put X into token Y because they said they were going to do Z. They didn't do Z, and instead, the people behind Z are buying yachts. And we know where they are."

[1] [https://ftalphaville.ft.com/2017/09/04/2193198/paris- hilton-...](https://ftalphaville.ft.com/2017/09/04/2193198/paris-hilton-backs- an-eyebrow-raising-crypto-project/)

<comment><AUTHOR> The SEC has been taking a surprisingly soft touch, but is actively phoning up ICO promoters to suggest they get it together: [https://davidgerard.co.uk/blockchain/2017/09/01/the-sec- told...](https://davidgerard.co.uk/blockchain/2017/09/01/the-sec-told-you-it- was-watching-now-its-calling-ico-promoters-protostarr-benjacoin/)

<comment><USER9> The SEC is doing a good job, then. That gets the message across that a "take the money and run" ICO isn't going to end well for the promoters.

<comment><AUTHOR> Note that Synthorn has absolutely no contact details available (and an anonymised whois) except an address to send them Ether. They have a promotional Facebook and Twitter, I suppose the SEC could subpoena them ...</comment></comment></comment></comment></comment>


China Plans to Launch its own Chips for Laptops and Servers - <AUTHOR> http://www.crazyjoys.com/china-plans-to-launch-its-own-chips-for-laptops-and-servers-amd-intc-armh,20121704

<comment><USER2> I guess, these Chinese companies are going to violate the IP of US companions like Intel and AMD but Intel and AMD cant do anything to stop them in China</comment>


Our solution to student loans and graduate unemployment - <AUTHOR> Our idea is an e-learning website linked to a freelancing website. Users take courses uploaded by instructors in the e-learning part of the website and apply what they learn in the real world by completing tasks for companies in the freelancing part of the website.
You can only apply for a task if you have completed its required courses, ensuring that you have the knowledge required to complete the task. In return, each task should have a minimum pay to ensure that users are not underpaid and have a steady source of income.
The aim of this idea is that people no longer have to pay expensive student loans to learn job related skills and that they can find jobs more easily as they can apply for any task as long as they have completed its required courses.
We are still in the pre-launch stage and we would encourage you to sign up now if you're interested so that we can convince instructors and companies to post courses and tasks on our site, allowing us to launch the site faster for you to use it.
Also, feel free to suggest any ways to improve our app. <comment><USER2> I love the idea, but do you also get certificates? Sadly even in the IT world many corporate companies still require us to show some formal documents that show we do indeed have the skills we claim to have.

If not, I feel it will become an feedback loop where I can only get work from the website. Because I can't show an website to an prospective employer who isn't in on the loop.

Also as an possible educator, how would I get paid? Like do you take an percentage off from the freelance work then distribute between the "required" courses or how does that play out? or do I get an cut from the course payment?

Is there also a going to be a vetting process and/or course structure and/or acceptable courses depending on what they teach?

One last thing, why separately do accounts for instructors and enrolled people? What if I want to both teach and learn?

<comment><USER3> Hi, Im the cofounder of this app I can also answer your question.

We do not have certificates like the traditional educational system and instead we have a resume-like profile page that shows the courses you have completed and the tasks if you have completed.

This way companies would know that you actually have the knowledge that you claim and can see your practical experience in completing tasks, which is something you won't be able to prove with just a degree certification.

If you are an instructor you get paid when someone enrols in your course. We have 2 separate accounts for instructors and users for security reasons.

Also, since you're interested could we invite you to sign up so that we can launch earlier.

</comment></comment><comment><AUTHOR> Reach Us At: [https://enrole.herokuapp.com/](https://enrole.herokuapp.com/)

Sign Up Now: [https://enrole.herokuapp.com/signup](https://enrole.herokuapp.com/signup)</comment>


A quick background recommender systems including the BPR algorithm - <AUTHOR> http://www.eggie5.com/99-recommender-systems <comment><AUTHOR> Most rec-sys these days are focused on collaborative filtering techniques based on SVD. This is the motivation behind the winning netflix challenge submission.</comment>


Potential Employer Cancels Return Flight - <AUTHOR> https://workplace.stackexchange.com/questions/126565/potential-employer-cancels-return-flight# <comment><USER2> From a response:

> "naming and shaming" is an option ... but ... Stack Exchange is not the > platform to name and shame on.

This might be a better place for that. Shaming seems to be an appropriate response if the allegations are correct. While a legal response would likely cost more than the damages, it could be a service to readers to warn us. The company allegedly at fault is of course free to reply here as well.

Mr. Kendall, who did it?

</comment><comment><USER3> dupe: [https://news.ycombinator.com/item?id=18921714](https://news.ycombinator.com/item?id=18921714)</comment>


Netflix's $12M Gamble on "Beasts of No Nation" - <AUTHOR> http://www.fastcompany.com/3052347/behind-the-brand/inside-netflixs-12-million-oscar-seeking-gamble-on-beasts-of-no-nation <comment><USER2> Idris Elba is an excellent actor and I'm looking forward to watching this. I'm also hoping to see him as the next James Bond when Craig's contract runs up.

<comment><USER3> He is an amazing actor with a great range, and I'm hoping he is not the next James Bond. It would be a waste. The thought that some studio is not willing to do something original with someone like that troubles me greatly. Plus, recycling these roles with simple replacement just seems insulting. Its basically saying that there is no original thought to culture and audiences cannot accept the new.

<comment><USER4> I'm kind of willing to give the Bond franchise a pass on this front. It's been a brand, if not its own mini-genre, for longer than I've been alive. And it's not like Hollywood is performing brand necromancy on it; it's been active for a good bit of that time. It's more like Doctor Who and less like Charlie's Angels.

<comment><USER5> Wow, Doctor Who is actually a fantastic comparison I had never thought of before.

<comment><USER6> Fans of both franchises have been making this comparison for years, and one of the more famous fan theories is that Bond is a Time Lord (which is usually tongue-in-cheek... well, a little bit at least).

I always like it when someone new notices the similarities :)

</comment></comment></comment></comment></comment><comment><USER7> Time to buy Netflix stock that fell 10%.

<comment><USER8> still expensive

</comment></comment><comment><USER9> Excellent. It still baffles me why I have to drive to the movies to pay $10, when I can pay the same $10 bucks at home.

<comment><USER10> Do you have a 20 foot wide screen and top of the line surround sound system at home (not the mention the snacks)? Going to the theater is a much better experience to me than sitting at home.

<comment><USER11> It's a matter of perception. Sitting closer to a smaller 4k screen will give you a better experience than the big badly dimmed screen at the movies. A good pair of quality headphones ($300+) will also sound better than the often too loud sound system in the cinema. I can also set my own EQ and add sound compression to movies where the music, dialogs and special effect are badly balanced.

As for the snacks, they charge double or triple the price of everywhere else on the planet.

The only reason I go to a theater is out of nostalgia. For a while, I thought that 3d would give me a reason to go the the cinema, but I've yet to experience 3d in a satisfying way.

<comment><USER12> I'll have to echo aidenn0 here with respect to the sound. I have pretty good headphones (Beyerdynamic T90s) and love them, but when it comes to a movie experience I want a good five-channel speaker setup with proper level calibration and an amplifier that has a home theater EQ profile built in. To me, that's more important than the screen -- I only have a 42" 720p TV, but I'd rather watch movies on it than on 55" 1080p screens with more anemic sound systems. (Granted, my TV is a Pioneer plasma model, so for a 720p screen it's really good.)

I still like going to theaters occasionally, though. For all of the flaws -- including the snack prices, definitely -- sitting closer to a 60" screen at home is not going to truly replicate the effect of sitting twenty feet away from a 720" one.

<comment><USER13> You probably don't care (neither do I), but the reason the snack prices are so high is because the theater makes almost no money from the movie, in the first few weeks.

My beef is with the quality of the snacks, not the prices themselves.

</comment></comment></comment></comment></comment><comment><USER14> Just saw this film. High caliber stuff. Highly recommended.

Quick fun fact: It was directed by Cary Joji Fukunaga, director of S1 True Detective</comment>


Tokyo medical school altered test scores to keep women out - <AUTHOR> https://www.straitstimes.com/asia/east-asia/tokyo-medical-school-altered-test-scores-to-keep-women-out <comment><AUTHOR> "Women often quit after graduating and becoming a doctor, when they get married and have a child," one source told the Yomiuri, in justifying the blanket alterations of admission scores.

"There is a consensus inside the university that male doctors support the university hospital," which often requires emergency duties and long shifts, the source told the daily.</comment>


The quest to untangle why pregnancy can turn deadly - <AUTHOR> http://www.wsj.com/articles/the-quest-to-untangle-why-pregnancy-can-turn-deadly-1481298026 <comment><USER2> Compared to egg-laying (first amniotes, approx 340 million years ago), pregnancy hasn't been around that long. Combined with vertebrates adaptive immune system, a placental-mammal-style pregnancy is bound to be problematic. Interesting that they're trying to untangle specifics, but the overarching "why" isn't that mysterious.</comment>


Logic programming on the JVM and Javascript - <AUTHOR> http://www.is-research.de/info/vmlanguages/tag/logic-programming/ <comment><USER2> I didn't see anything much to do with Javascript here. Unless you're meant to use some of these libraries (such as Drools) through something like RingoJS.</comment>


Google Latitude API could be as transformative as Facebook's Social Graph - <AUTHOR> http://redeye.firstround.com/2010/05/location-in-the-cloud.html <comment><USER2> There's two kinds of apps going on here, and I think it's pretty anecdotal for why this probably wont be as transformative as fb's social graph (it's an apples vs. oranges comparison anyway). Google always builds the engineering app not the social app like they did with wave/buzz. This WILL be useful for people who are building the examples google talks about here [http://googlemobile.blogspot.com/2010/05/do-more-with- google...](http://googlemobile.blogspot.com/2010/05/do-more-with-google- latitude-and- your.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed:+OfficialGoogleMobileBlog+%28Official+Google+Mobile+Blog%29) like turning off and on your lights when you get close to house etc.

but as usual, google only understands the engineer and focuses too much on utility and not enough on people.

There are somethings people do in fact WANT to check into (ignore the privacy issue entirely for now, just from a visceral product level), not just have automatically imported because the act of checking in is in and of itself an act of projecting identity. People who want to show what bar they are at because they are showing that they are cool want to press a button and get the reward right there of "I'm cool." Knowing that your phone is projecting that automatically wont give people the same rush as showing up at the bar and checking in.

<comment><USER3> But I don't see anything here that blocks the "check in" approach, if anything, it makes it easier to implement. Instead of needing to develop your own app for each mobile platform and using their location API, you just make a web page that asks for confirmation to access the user's Google Latitude location, and all you need to do is develop the interface for whatever human provided info you want. The location pick up is taken care of. (Of course, I don't know how this compares to just using HTML5 location APIs... perhaps that provides a better approach for check ins.)

The only problem I see with this is that, in my experience, Google Latitude 95% of the time tracks location by cell tower, which doesn't even narrow down which block you are on, much less which bar you are in.

<comment><USER2> Now the user has to manage their privacy for a bunch of apps through Google's central server instead of the app itself, and the app now needs to talk to google as well - seems like kind of a drag to me. Extra moving part for dev, and for user kind of like having settings for a game in your system preferences, sure it works but it's a bit odd.

And the cell tower problem too, which I didn't know about.</comment></comment></comment>


On User Retention as a Service - Response to Paul Stamatiou's post - <AUTHOR> http://blog.totango.com/2011/12/on-user-retention-as-a-service/

<comment><AUTHOR> A response to Paul Stamatiou post: "Startup Idea: User Retention as a Service" [http://paulstamatiou.com/startup-user-retention-lifecycle- em...](http://paulstamatiou.com/startup-user-retention-lifecycle-email)</comment>


The ones who walk towards Acre - <AUTHOR> http://www.gwern.net/fiction/The%20Ones%20Who%20Walk%20Towards%20Acre

<comment><USER2> How is this relevant to HN?

<comment><USER3> Assassination markets (and prediction markets in general) are fairly intimately tied to cryptocurrencies; writings on them included them as thought experiments back in the 90's.

<comment><USER4> It's actually particularly relevant because someone seem to be making a serious effort at one using, naturally, Bitcoin: Sanjuro's "Assassination Market" (see [http://www.gwern.net/Silk%20Road#future- developments](http://www.gwern.net/Silk%20Road#future-developments) for details).

It's hard to tell if AM's a scam or not by the nature of assassination markets, which turns out to be an interesting observation, IMO - it never occurred to me, reading the original speculations, that assassination markets would be so much harder to bootstrap than drug markets like Silk Road.

<comment><USER5> Jim Bell gave a straightforward way to bootstrap - start with ordinary prediction market and gain trust.

And that is probably why we won't get them, practically nobody will risk their profit from legal service by turning them into assasination market.</comment></comment></comment></comment>


Video: Quantum Levitation - <AUTHOR> http://jasonadriaan.com/post/11595319387/the-future <comment><USER2> Reminds me of a great quote by Benjamin Franklin:

"The rapid progress true Science now makes, occasions my regretting sometimes that I was born too soon. It is impossible to imagine the height to which may be carried, in a thousand years, the power of man over matter. We may perhaps learn to deprive large masses of their gravity, and give them absolute levity, for the sake of easy transport. Agriculture may diminish its labour and double its produce; all diseases may by sure means be prevented or cured, not excepting even that of old age, and our lives lengthened at pleasure even beyond the antediluvian standard. O that moral science were in as fair a way of improvement, that men would cease to be wolves to one another, and that human beings would at length learn what they now improperly call humanity!"

\-- Letter from Benjamin Franklin to Joseph Priestly (8 Feb 1780), quoted in "How Mumbo Jumbo conquered the World" by Francis Wheen

<comment> sans-serif Benjamin Franklin would be delighted to know that he woefully underestimated science's impact on agriculture. [http://en.wikipedia.org/wiki/File:Wheat_yields_in_developing...](http://en.wikipedia.org/wiki/File:Wheat_yields_in_developing_countries_1951-2004.png)

</comment></comment><comment><USER3> Pure marketing. "Quantum levitation" is just flux pinning[1] as seen in all "high temperature" superconductors. All you need a chunk of type 2 superconductor, a strong magnet, and some liquid nitrogen. Note the 852 videos on youtube: [http://www.google.com/search?q=superconductor+levitation&...](http://www.google.com/search?q=superconductor+levitation&source=univ&tbm=vid)

You can shell out 80 bucks and do it yourself: [http://sargentwelch.com/superconductivity-suspension-and- lev...](http://sargentwelch.com/superconductivity-suspension-and-levitation- kit/p/IG0038153/) (LN2 not provided.)

There doesn't appear to be any novel physics here at all.

1: <http://en.wikipedia.org/wiki/Flux_pinning>

<comment><USER4> > All you need a chunk of type 2 superconductor, a strong magnet, and some > liquid nitrogen.

This isn't entirely accurate. A "chunk of type 2 superconductor" would just show the Meissner Effect, which is different than "flux pinning". The Meissner Effect is how superconductors essentially repel magnetic fields, resulting in levitation; it wouldn't necessarily pin the levitating body in-place such that it could follow some track for example.

Flux pinning occurs when _some_ magnetic fields penetrate the superconductor in discrete "tubes" through the imperfections (along the grains) of the superconductor. In order for flux pinning to happen, you must have an extremely thin superconductor (in the case of the video, it's actually a sapphire crystal wafer with a 1-micron thick coating of superconductor ceramic material).

EDIT: Technically, you could also get flux pinning if you were to supercool the superconductor (i.e. make it a superconductor) _while_ it's in the magnetic field of the magnet.

<comment><USER5> I played quite a bit with the Meissner and the Flux pinning effect. But I was never able to change a flux pinning "on the fly". You always had to reheat the superconductor to something over the transition temperature and then cool it down again inside a magnetic field (in the desired position). But then, it was quite strongly locked in that position and would snap back to where it was when moved.

So, I'm quite curious on how this works ;) Is it because it's a very thin superconductor in this video?

</comment></comment></comment><comment><USER6> This is very cool. Another video with a bit of an explanation as to why - <http://www.youtube.com/watch?v=VyOtIsnG71U>.

<comment><USER7> Thanks. I'm not sure I understand the part about "quantum flux tubes". I take it that they're leaks through flaws in the superconductor (which should exclude the field entirely). Is the superconductor is being gripped or pinned by these lines of force running through it, like a piece of cheese on a toothpick? But that doesn't quite explain how it can move along a field.

<comment><USER4> I think the magnets on the track piece may be arranged NSN like this:

      NNNNNNNNNN
      SSSSSSSSSS  ==>
      NNNNNNNNNN

Which allows movement as indicated. In the part of the video where it's just locked stationary above a square magnet, it appears maybe the magnet as this arrangment:

      NNN      NS
      NSN  or  SN
      NNN

Which locks it entirely in-place, not allowing movement. And then in the part where it's spinning, I think maybe the magnet is S on the inside and N on the outside or something:

          NN
         NSSN
        NS  SN
         NSSN
          NN

Allowing it to spin. But this is speculation based on my limited understanding (but I noticed no one else was answering, so I thought I'd give a shot).

</comment></comment></comment><comment><USER8> Quick question: If the object is the temperature of liquid nitrogen, how can he touch it for so long?

<comment><USER9> Leidenfrost effect:

<http://en.wikipedia.org/wiki/Leidenfrost_effect>

The stuff of which awesome party tricks are made. I have myself put a very small amount of liquid nitrogen in my mouth and blown it out, although I then heard that the guy who taught me that trick (Jearl Walker) cracked a tooth doing that, so I never tried it again. And _for the love of god do not swallow or you will literally kill yourself very painfully_ \-- see footnote 3 of the above Wikipedia article.

I think I'll stick with dipping fingers briefly into LN, which is way less stupid. Done that many times. Do not get it on your clothing, though, because then you can't retreat quickly and the frost is going to bite!

<comment><USER10> "What was really astounding about Michael's case is that the liquid nitrogen instantly expanded from a volume of about 3 or 4 cc's to about 3 or 4 liters and then dissected into five separate body compartments"

Ouch. <http://www.wpi.edu/news/19989/nitro.html>

<comment><USER9> Yes, if this Wikipedia article had existed when I was a college senior I'd never, ever have tried that particular party trick. ;)

Yet another example of how the web makes us much, much smarter.

I estimate that I used a tiny sip, not 3 or 4 ccs, but still. Crazy risky.

<comment><USER8> A teaspoon is 5ccs. 3-4cc IS pretty much a tiny sip, unless you have excellent lip-control.

</comment></comment></comment></comment></comment><comment><USER11> When I came into work this morning this was at the top of reddit.com/r/all (got to get the procrastination out of the way first thing right!)

A guy spoke up regarding his father who works in the field. Currently doing Q&A

<http://redd.it/lfsjn>

<comment><USER12> Is there a layman's summary regarding the significance of that paper linked on reddit?

<comment><USER3> Completely irrelevant. It's a theory explaining how Type II superconductors work, published five years ago, in a Chinese journal that has an impact factor of 0.512 ( _Nature_ scores 30.98, for comparison.)

<comment><USER13> What's the relevance of "impact factors"? I understand the basic idea behind them, but I don't think publishing research in a low impact factor journal should automatically make said research "completely irrelevant".

<comment><USER3> It's completely irrelevant because it has little to nothing to do with the original post, much like how you wouldn't link to a paper on algorithmic complexity in a post about Facebook, because "they're both about computers."

Additionally, the author of the paper displays some worryingly crackpot-like symptoms. He claims that it's "Nobel worthy", (!!) but Citebase can find _no_ citations.

I know nearly nothing about condensed matter physics, but skimming the paper reveals that his theory doesn't really make any testable predictions, much less the "grand slam" predictions that would result in a Nobel, like room-temp superconductivity.

Impact factor is tremendously flawed, but as a quick sanity check, when you're not sure if something makes _any sense at all,_ it is of great use.

<comment><USER14> He cited it himself in two other papers :/

As far as crackpot symptoms, it looks like he's a biblical literalist too!

<comment><USER3> Ah ha, you missed my very careful weasel wording! I said that _Citebase_ found no citations, not that it actually _had_ no citations, mwa ha ha.

</comment></comment></comment></comment></comment></comment></comment><comment><USER15> So, the electrical engineer in me says that this is because any movement of the magnet would induce an electric potential in the superconductor. But because such a potential would create an effectively infinite amount of current requiring an infinite amount of work, the magnet is unable to move.

Or from a "cause-and-effect" viewpoint, movement of the magnet induces a current loop in the superconductor, the creation of which creates an opposing magnetic force.

Either way I believe this is the same principle behind electric motor braking (e.g. when you short-circuit the inputs of a motor). I believe you would also see a similar effect by dropping a magnet down a tube encircled with many (or perhaps one spiral) loop of wire -- the magnet's descent will be slowed by eddy currents in the loops.

Edit: Aha, this is just half the story. The superconductor is prevented from spinning due to flux pinning: <http://en.wikipedia.org/wiki/Flux_pinning> (or what the researchers call quantum trapping / quantum locking)

<comment><USER16> But, it clearly does not take an infinite amount of force to move the "locked" superconductor, because you can adjust it by hand. The real question is, how _much_ force does it take?

<comment><USER15> Right, I believe this is a function of how much of the magnetic flux does not encounter the superconductor. But IANAP, just a former EE, so I don't know that this is 100% correct.

</comment></comment></comment><comment><USER17> Is this "quantum locking" just a rebranding of the Meissner Effect?

<http://en.wikipedia.org/wiki/Meissner_effect>

<comment><USER18> Quoting a comment in the video linked to by fybren:

"This levitation is NOT due to the Meissner effect. It is negligible since we use thin films. If it were the Meissner effect the field would get distorted on a length scale of the diameter (~cm) and then two discs hovering above and below each other would affect it other. Which is clearly not the case. The discs are actually trapped in constant field contours rather than levitating."

</comment></comment><comment><USER19> On a more serious note, I'd love to find out more about just how much weight they think this tech could support in the future. Those implications could be insane.

<comment><USER20> Agreed. If the "floating" (I know its not actually floating in the traditional sense) object could carry its own light-weight cooling system then you wouldn't need to chill the entire unit to super cold temperatures. You might only need to cool the superconducting layer.

<comment><USER21> The thing is, we are all waiting for room temp superconductors. That paper on the Reddit post seems to have some breakthrough regarding this if I'm not wrong.

</comment></comment></comment><comment><USER22> Direct link: <http://www.youtube.com/watch?v=Ws6AAhTw7RA>

</comment><comment><USER23> As a thought experiment, could the effect demonstrated here be used for a transport system on a much colder planet with a much stronger magnetic field (I do realize that these two properties tend to correlate in opposite directions)? What about in our arctic regions, potentially over a magnetic track to interconnect enclosed "settlements"? I'm guessing it would be less cost-effective than other types of transport if even possible, but many times cooler.

</comment><comment><USER24> Will this scale to train cars weighing a few tons each?

So if this was demonstrated live to congress, do you think they'd finally fund a few miles of super-conducting trains for research?

<comment><USER25> Or they can cross the Pacific ocean.

<http://en.wikipedia.org/wiki/JR-Maglev>

</comment></comment><comment><USER26> blogspam.

<comment><AUTHOR> not exactly, I just posted it to tumblr. It would be blogspam if I were running ads, but I don't.

<comment><USER27> It's still blogspam even if you're only craving attention.

</comment></comment></comment><comment><USER28> Hm, I remember getting excited about this about 23 years ago, when I was still at school.

Can't help wondering if perhaps 50 years ago people were also getting excited about it and expecting to see cool things to come out of it in the near future.

Not saying that there couldn't, but I can't help feeling vary about the "technology of the future claim".

</comment><comment><USER29> Not particularly quantum mechanical.

Well, no more so than everything else you might happen to see in your everyday life.

<comment><USER30> Well, superconductivity is an inherently quantum phenomenon, more so than other things in everyday life; see <http://en.wikipedia.org/wiki/Cooper_pair> .

<comment><USER29> Eh. _Solids_ are an inherently quantum phenomenon.

</comment></comment></comment><comment><USER31> Am I really the first one who immediately thinks about Hoverboards???

<comment><USER32> Wow! But that'd need magnets all over the ground!

<comment><USER33> I think one magnetic half-pipe would be feasible, the question is could a board be made that could support a small human?

</comment></comment></comment><comment><USER34> Isn't there already a shortage of rare earth minerals, used to make strong magnets? Is that going to be a problem for extending uses of this outside a lab?

But: really cool video.

<comment><USER35> You could always use electromagnets.

</comment></comment><comment><USER36> how much force (if any) is required to break it off the track? Could that disk be slingshotted around at hundreds of miles per hour and stay on tack?

<comment><USER37> I'd imagine whatever force is needed is proportional to the strength of the magnets. Given that he can pull it off I can't imagine that specific setup requires all that much force for it.

</comment></comment><comment><USER38> That has to be one of the most engaging conferences I have ever seen. The science demos are just too cool. If I have the time I'm going next year!

</comment><comment><USER39> Quantum physics professors do that in their first lecture, it's getting old.

</comment><comment><USER40> Put this in a vacuum... perpetual motion?

</comment><comment><USER41> How does this work?

</comment><comment><USER42> At 1:30 the disc on the tracks stops without any outer interference, am I missing something in the video?

<comment><USER43> Yeah - when I saw that after watching the Take This Lollipop video, which is an extremely well-done fake, I immediately lumped this one into the "cool special effects, but not real" category.

So ... this is actually real? If so, that's pretty awesome :)

</comment></comment><comment><USER44> Flying cars here we come?

<comment><USER45> Sure, but you can only fly at constant altitude along longitude lines. If I understand the effect correctly.

<comment><USER46> This would have to be over a magnetic surface - like maglev trains <http://en.wikipedia.org/wiki/Maglev> (which apparently are not technically trains).

</comment></comment></comment><comment><USER47> How much longer before we all drive landspeeders?

<comment><USER19> Too long.</comment></comment>


Tech and Programming Reddit Communities for Coders - <AUTHOR> https://twitter.com/myviralmag/status/1159079831306420225 <comment><USER2> The [https://news.ycombinator.com/newsguidelines.html](https://news.ycombinator.com/newsguidelines.html) asks for original sources. The tweet simply links to a website without additional information (value), please submit the website directly.</comment>


Powerset: Win a tshirt! - <AUTHOR> http://www.powerset.com/blog/articles/2008/06/08/find-factz-get-a-t-shirt

<comment><USER2> Here's a compairson of Powerset, Google and Yahoo:

what are the symptoms of dementia?

<http://s281.photobucket.com/albums/kk207/dementiaquery>

Notice that 60% of the results on Yahoo and Google's pages are sponsored links that show no immediate information. The Powerset result is much more useful.

That said, the Powerset output would be little better if it used the full width of the window.

One thing I really like about the Powerset results is how you can click on the arrow to the left of the result to open a more detailed summary of that result in a small text box, allowing you to scan the results without losing context.</comment>


HHVM's Profile-Guided Region JIT - <AUTHOR> http://hhvm.com/blog/2017/02/17/region-jit.html <comment><USER2> I was honestly surprised how well PHP7 fared against HHVM. No JIT, and likely a much smaller team and budget. Most of the comparisons I've seen show them as roughly the same performance.

<comment><USER3> PHP7 was a huge performance leap over 5.x, I saw all the benchmarks and they looked impressive (100% performance, 50-80% reduction in memory usage) and expected the usual "Ok but in the real world I'll get maybe 10-20% because benchmarks" and nope, in production I see exactly what the 5 vs 7 benchmarks show.

The memory reductions when dealing with large arrays (pretty much the only datatype in PHP...) are colossal.

<comment><USER4> > arrays (pretty much the only datatype in PHP...)

linked-hash-map-arrays, they are :)

</comment></comment></comment><comment><USER5> Has anyone tried building a PHP runtime based on Truffle?

It might not be as fast as a dedicated JIT with a big team behind it, but it seems Facebook's HHVM effort is relatively small as these things go.

Is there anything about PHP that would make Truffle a bad fit? I ask this as someone who knows next to nothing about either PHP or Truffle!

<comment><USER2> >Is there anything about PHP that would make Truffle a bad fit?

Perhaps one barrier would be the insane number of built-in functions. There's 1000+[1]. And, as far as I can tell, most of them tied to underlying C code versus being written in PHP themselves.

The other might be that because of the built-in templating thing, you would have to parse html as well, to find the embedded PHP. I'm not sure how well that aligns with Truffle's approach. Things like this:

        <?php foreach ($foolist as $foo) { ?>

<?php echo $foo;?>

        <?php } ?>

[1] Try: php -r 'var_dump(get_defined_functions());' | less

<comment><USER6> Built-in functions are certainly a pain. They pose a similar problem for Ruby (which there is a Truffle implementation of). I think the best way around is to rewrite them in PHP, but it may not be tractable to do this with the same semantics. Another option is to run the C code that implements the builtins using the same JIT as you use for the PHP code. Then you can inline through the builtins, which is one reason why HHVM may be slow.</comment></comment></comment>


The best reset password flow - <AUTHOR> https://medium.com/@shlominissan/the-best-reset-password-flow-a216fe0e94c5 <comment><USER2> Good pieces of advice but I have a honest question:

> There's nothing worse than waiting for a reset password email — use an SMTP > server, you don't want your emails queued up.

Do SMTP servers never queue messages, not even under load? That would be a surprise.

Maybe the advice here is to use a separate account to be able to bypass less important notifications.</comment>


Carlo Rovelli on challenging our common-sense notion of time - <AUTHOR> http://nautil.us/blog/forget-everything-you-think-you-know-about-time <comment><USER2> I am not really skilled in physics and have never understood why time would be a tangible dimension like, say, width or height, instead of a mathematical construction to argue about change.

I get it that it is convenient to talk of change in something, like movement from state a to state b, under the guise of wrapping it in "time", but is there some physical argument in support of time in general? Honest question.

Living beings getting older is their cells becoming more and more inefficient in division and cell repair. One could likely achieve the same effects with chemicals, but doing so would not mean time has run faster.

The concept of time for humans seems to be all about observable change, which needs an observer with a memory to compare the current state with previous state to be able to say: time has passed.

A rock changes via erosion and such, but it has no memory, and cannot observe anything. Does a rock feel time? Of course not. Does it exist "in time"? Does it, without an observer that somehow measures the flow of time (via changes in Cesium atoms or something)? Or is the rock just existing and under the whims of all forces of nature that might impact it and change it into smaller pieces and eventually to sand, and so on.

I guess my question is: what exactly is time, physically, and why should it have to exist as some sort of a physical process in the first place.

<comment><USER3> I have a kind of followup question (which, if I understand correctly, was touched on a bit in the article). If time is a tangible dimension, is it possible that the "passage of time" is an illusion? I remember the past and because of causality, the events are ordered. Time seems to flow from the past to the future and it never flows from the future to the past. This seems obvious to us, but I've always wondered why time doesn't flow backwards.

Just to take a silly example, what if all the "points in time" just exist (and are ordered -- I don't propose to break causality)? They don't flow at all. From my perspective, at every "point" along the time axis, I can recall the past and it will be ordered as if it "happened", but each point could be independent (though constant). If I could remember "forward" through time, then this would be obvious, but since I can only remember "backward" through time, at every point it appears as if I have progressed through time.

I suppose the interesting thing is that causality is uni-directional. Things can only happen in a certain order in the past. But this is not true of the future. Even if I have perfect knowledge of the present, there are some things I can not predict about the future (quantum mechanics FTW). I wonder why that is (because we are flowing through time? Ha ha!)

Sorry for the diversion, but if someone that is better educated than me could shed some light on the matter, I'd be grateful.

<comment><USER4> You've rediscovered eternalism: [https://en.m.wikipedia.org/wiki/Eternalism_(philosophy_of_ti...](https://en.m.wikipedia.org/wiki/Eternalism_\(philosophy_of_time\))

<comment><USER5> If eternalism is real it's hardly fair to say he _re_ discovered it - all the discoveries have always existed.

<comment><USER6> Discovery is not invention, it's literally just noticing (or uncovering in a metaphorical sense) something that was always there.

<comment><USER7> How do you know?

</comment></comment></comment></comment></comment></comment><comment><USER8> > Unlike general relativity, quantum mechanics, and particle physics, > thermodynamics embeds a direction of time.

This is the bit that irks me. Quantum mechanics, the real QM that physicists actually use, involves collapse of the wavefunction. This is absolutely time- asymmetric. But in all these discussions of "why is time one-way?" this never seems to be mentioned. Apparently QM is not a real theory, and just a placeholder until we can work something out properly. Irk!

<comment><USER9> Many physicists do not believe that collapse of the wavefunction is a thing.

<comment><USER8> Ok, but why is there no discussion at all? I stand by my irk.

<comment><USER10> You _can_ get every conclusion you want out of QM without any wavefunction collapses, so there's no need to discuss it (depending on your purpose) and if you're an MW-er you'd argue that, further, there's no reason to believe that it even happens. Since there are several self-consistent "piles of words" that all talk about the same math but contradict each other, (Does the wavefunction collapse? Does 1600s literature simulate the simulacrum?) not talking about it seems completely justified.

<comment><USER8> > You can get every conclusion you want out of QM without any wavefunction > collapses

I don't think so.

> "piles of words"

I definitely agree about the piles. Maybe ordinary language is just to feeble for this stuff.

</comment></comment></comment></comment></comment><comment><USER11> Would it be fair to say that the second law of thermodynamics is only "a law" given our human perspective of the direction of time? If time has no "arrow", but a memory is only possible in non-decreasing entropy which is our perspective, there can be another perspective in which the big bang is the future and our future is the past, only we cannot comprehend it because a memory is not possible in decreasing entropy?

<comment><USER12> The second law of thermodynamics is about entropy, which is an observer dependent quantity. It is the discrepancy between what one knows about a system (e.g. its temperature) and its state (e.g. the position and momentum of every particle in a classical gas). A being that knows the exact state of a system does not observe entropy increasing or decreasing. At least classically.

I don't understand the rest of your question.

<comment><USER13> Digging deep into my memory of classical mechanics, I think this is along the right lines. However, I believe (seem to recall) entropy is an actual measure of the number of ways a system can be ordered in its details and still produce the same generalized outcome.

A crystalline solid has relatively low entropy because you can be reasonably sure where each nucleus is, as they are highly ordered. A gas or plasma can have the nuclei distributed nearly randomly. Both systems can be measured generally (stochastically, or of their overall or average properties) but the number of ways you can organize all the nuclei to get those results very different between the two systems.

Feel free for someone more knowledgeable to correct or expand.

<comment><USER14> That's basically the gist of it. The entropy of a system is proportional (via Boltzmann's constant) to the natural log of the number of available microstates, where _microstates_ are configurations the system could be in, and _available_ denotes that they have the same total value for all conserved quantities as the aggregate system. Consequentially the system is free to spontaneously transition between any of its available microstates.

</comment></comment></comment></comment><comment><USER15> If you found that interesting you might also enjoy Rovelli's defence of Aristotle's physics: [https://arxiv.org/abs/1312.4057](https://arxiv.org/abs/1312.4057)

</comment><comment><USER16> We know that the universe went through various very fast state changes in its very first fraction of seconds.

Given that the gravity must have been immerse then how should we understand this time?

<comment><USER17> >Given that the gravity must have been immerse then how should we understand this time?

We don't really know. There are speculative theories, but they don't all agree.

It's very difficult because the temperature would have been so hot at the very start that instead of four fundamental forces (of which gravity is one), we would have had only one. There's also the Hartle-Hawking State, which is a theory that proposes at the very "start" there simply was not time, only space, and that time coming into existence was part of the process that occurred during the planck epoch.

There's also the Grand unification epoch, inflationary epoch, electroweak epoch, quark epoch, and hadron epoch that occurred in the universe before a second had passed, all with very different implications for how physics could have worked, so the answer would change multiple times during that period.

</comment></comment><comment><USER18> This guy uses rather confusing descriptions of his theories and ideas. I respect his approach but other are much better in explaining these topics.

<comment><USER19> Rovelli mentions his paper from 2009 with the title 'Forget Time' in the video. The paper can be downloaded from [1].

I enjoyed the presentation. Talking for an hour on this kind of material with just a piece of string and a couple of watches is fairly impressive. The thought experiment with the wooden box and green/red balls (in two size categories unrelated to their colour) was thought provoking.

I'd like to see someone define/construct two sets of macrostates that give a different time scales in a system with one set of microstates. For all I know someone may have actually done that. The paper referenced does have a section on the 'thermal time hypothesis'.

[1] [https://arxiv.org/abs/0903.3832](https://arxiv.org/abs/0903.3832)

</comment></comment><comment><USER20> > _In fact, clocks tick slower when they are in a stronger gravitational > field_

They shouldn't, if they are properly made. They should tick and measure at their usual rate. Their local timeframe is out of whack with somewhere else, but that's got nothing to do with the clocks.

<comment><USER17> It's unfortunate you're getting downvoted, because this is correct.

For anyone that is dubious: Black holes are one of the common ways this gets discussed, because it's such an extreme example, and you can read more about it at [http://www1.phys.vt.edu/~jhs/faq/blackholes.html#q11](http://www1.phys.vt.edu/~jhs/faq/blackholes.html#q11) \- this goes into a bit about photons and the event horizon - you can ignore that and just consider it in regards to the time dilation effects of gravity.

<comment><USER20> Thank you. It is faintly disturbing how many downvotes short, factually incontrovertible comments may often garner on HN.</comment></comment></comment>