Boring Co. gets permission to begin digging in Maryland - <AUTHOR> https://techcrunch.com/2017/10/20/elon-musk-gets-permission-to-begin-boring-co-digging-in-maryland <comment><USER2> More details about the site in this article: [http://www.govtech.com/fs/infrastructure/Maryland-Issues- Con...](http://www.govtech.com/fs/infrastructure/Maryland-Issues-Con..).

"Hogan administration officials said Thursday the state has issued a conditional utility permit to let Musk's tunneling firm, The Boring Co., dig a 10.3-mile tunnel beneath the state-owned portion of the Baltimore-Washington Parkway, between the Baltimore city line and Maryland 175 in Hanover."

<comment><USER3> That link doesn't work for me but this one does: [http://www.govtech.com/fs/infrastructure/Maryland-Issues- Con...](http://www.govtech.com/fs/infrastructure/Maryland-Issues-Conditional- Permit-for-Hyperloop-Tunnel.html)

</comment></comment><comment><USER4> One of the big arguments against public transit is that it's infeasible to dig tunnels. If this project succeeds, I wonder what kind of contorted logic will arise, arguing that digging tunnels for cars is feasible, but digging tunnels for subways is still infeasible?

<comment><USER5> I thought the reduced diameter needed for cars allows lower cost/faster tunneling. Also, making it for cars solves the "last mile" problem that makes public transit unusable in suburban settings.

<comment><USER6> Not so sure about that. Some subway tunnels are barely wide enough to fit a single train. I don't think a car tunnel can be much smaller, even if you only allow sedans and somehow find another way to send an ambulance in case of emergency.

<comment><USER7> I think all the subway tunnels in the U.S., including those in Boston, Chicago, and NYC, are >24 feet in width. The London Underground's deep-level tubes are less than half that at <12 feet in diameter.

That said, I don't think American cities could run subway cars as small as in the London Underground even if they wanted to because of the Americans with Disabilities Act (ADA).

Also, it might be difficult to make cars that small that pass muster under Federal safety regulations. AFAIU, Federal regulations basically require subway cars to be built like tanks.

EDIT: >24 feet just seems too wide for the old, deep tunnels in the U.S., but I can't find any references that aren't from books at the turn of the 20th century, which have very inconsistent numbers. I said >24 because that seem to be the width of old cut-and-cover tunnels and newer deep tunnels. I'm going to go out on a limb--based on random sources--and guess that the really old tunnels still in use might be closer to 16 feet in diameter. Feel free to correct me.

</comment></comment></comment></comment><comment><USER8> I recall a debate early on that one of the hurdles to Hyperloop viability was obtaining right-of-way within city limits. Getting to the outskirts was seen as probably doable since obtaining right of way involves relatively large parcels and a fair whack of government owned land (i.e. freeways). But in a city, there would be too many players to satisfy and the ends of the line would not be able to get close the the center of the cities, greatly reducing the value of the system.

Tunneling within city limits may resolve that.

</comment><comment><USER9> What if hyper loop will turned to be hyper flop?

I mean, electric cars, then autonomous cars, solar roofs, batteries, hyperloops, boring company, send humans to the space and back.

Isn't too much to accredit one person?

<comment><USER10> If it flops, so what? We will have gained knowledge on some pitfalls. If someone dares to try again, we won't have to start from the beginning.

I also don't agree with your logic of … A person shouldn't accomplish too much in life? Is that what you are saying?

<comment><USER9> I am not saying a person should not. I am simply saying a person could not. You can't effectively run more than two companies at a time. And that is a rare success. Most are struggling running one. And here is a man running 5 or 6 companies each going to revolutionize another area in our life. It's just don't fit.

<comment><USER11> Musk isn't doing this by himself anymore than Trump is personally running the Air Force, Army, Navy, and Marines (or are the Marines part of the Navy?).

<comment><USER12> They are a part of the Navy, yes.

</comment></comment></comment></comment></comment><comment><USER13> I don't know why they're doing this, except out of pure tech-broism. It's obviously not financially viable.

Let's say it realistically costs $150 million a mile for the project (about average for tunnel boring - it'll actually be a lot more on the east coast due to it being solid rock and expensive labor, but let's be realistically optimistic). At 250 miles, that's $37.5 Billion right there. Let's be ridiculously generous and finance this over 50 years. Over 50 years, that's $750 million/year. Or, $2million/day. At $60/ticket, you need 34k daily riders.

And that's only for building the tunnel. I haven't even factored in operating or finance costs, nevermind the millions of other expenses that this needs. Stations are normally the most expensive part of a system, for example, and a station in NYC might cost $1 billion by itself.

Is this going to get 34,000 daily riders paying $60/ticket to NYC? I can see that happening with $10/ticket, but not at $60/ticket. For comparison, the entire DC Metro system itself has about 800k daily riders with about $5/trip.

And then you have the stupid HyperLoop concept itself, which hasn't even been invented yet. It's based on small single-car vehicles, which may carry a couple dozen people at most. Already you can see capacity issues: To get 34,000 people a day 24-7, you need 1400 fully-packed rides a day, or one every 6 seconds. You're not going to get single-vehicles to share a track every six seconds. You're already capacity limited. How do you even slow down? Ingress/egress?

And the concept itself is horrific: [https://www.youtube.com/watch?v=RNFesa01llk](https://www.youtube.com/watch?v=RNFesa01llk)

Like WTF people? How are there adults that believe any of this garbage?

If you know anyone in your company that believes in this, just fire them on the spot. Make examples out of them. There's no excuse for this.

Stick with what works: high-speed rail, which can transport a thousand people or more in one trip and doesn't need some dumb vacuum tube. This is the real competition for this.

Larry Hogan has failed Maryland.

And Elon Musk is the worst thing to happen to tech.

<comment><USER14> I liked your analysis, but it hinges on the $150 million per mile figure. Is there any data to back that up, or any reason you chose that figure? Is there any reason to believe that Boring Co's technology could lower the cost?

<comment><USER15> OP's method [1] works better backwards. Assuming 250 miles (l) financed interest-free for 50 years, we find an implied ticket price (p) of the cost per mile (c) divided by the quantity 73 times daily ridership (c / 73 r). Generalised, we get (l c) / (18250 r) = p.

New York City and Washington, D.C. are 229 miles apart [2]. The Acela has ridership of 3.47 million per year [3], or about 951 on average per day. Acela tickets cost no less than $99 [4]. Plugging in we find the cost per mile can be no more than $7.5 million.

That is 30% the cost per mile of the cheapest tunnel, the Shanghai River Crossing, and 5% the cost per mile of the median tunnel in Figure 5 [5]. On the other hand, the Falcon 9's list price [6] per pound to low-earth orbit is about $1,230. That's approximately 70% to 85% cheaper than the competition [7].

Naturally, you'd charge less than $99 and hope for more than a thousand daily riders. The trick is finding routes for which the price elasticity of demand is high, _i.e._ where reducing the ticket price by 1/2 generates more than a 2x demand boost.

[1] [https://news.ycombinator.com/item?id=15519733](https://news.ycombinator.com/item?id=15519733)

[2] [https://www.travelmath.com/drive- distance/from/New+York,+NY/...](https://www.travelmath.com/drive- distance/from/New+York,+NY/to/Washington,+DC)

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

[4] [http://www.nbcwashington.com/news/local/Amtrak-Lowers- Acela-...](http://www.nbcwashington.com/news/local/Amtrak-Lowers-Acela- Express-Fares.html)

[5] [https://tunneltalk.com/TunnelTECH-Apr2015-Arup-large- diamete...](https://tunneltalk.com/TunnelTECH-Apr2015-Arup-large-diameter- soft-ground-bored-tunnel-review.php)

[6] [http://www.spacex.com/about/capabilities](http://www.spacex.com/about/capabilities)

[7] [http://4.bp.blogspot.com/_VyTCyizqrHs/S9IabKEr1nI/AAAAAAAAHb...](http://4.bp.blogspot.com/_VyTCyizqrHs/S9IabKEr1nI/AAAAAAAAHbc/2qXZ169gNgE/s1600/space1.jpg)</comment></comment></comment>


"Plurality": A Short Film About Surveillance In 2023 - <AUTHOR> http://falkvinge.net/2012/10/05/plurality-an-amazing-short-film-about-surveillance-in-2023/

<comment><USER2> The music and feel reminds me a lot of Deus Ex - which is a good thing.

</comment><comment><USER3> Amazing video.

<comment><AUTHOR> I had a problem with the consistency of technology. For example, the benefit grid is highly advanced and yet they are still using helicopters to track people on the ground. If the grid is everywhere, why aren't there tracking monitors everywhere?</comment></comment>


Videos of Evolution in Action - <AUTHOR> http://www.theatlantic.com/science/archive/2016/09/stunning-videos-of-evolution-in-action/499136/?single_page=true <comment><USER2> > The experiments, described in the Sept. 9 issue of Science, are thought to > provide the first large-scale glimpse of the maneuvers of bacteria as they > encounter increasingly higher doses of antibiotics and adapt to survive — > and thrive — in them.

The BBC TV programme Horizon showed the same giant petri dish 4 years ago. This post contains a link to a slightly different clip with a smidgen more background.

[https://news.ycombinator.com/item?id=5356309#5356479](https://news.ycombinator.com/item?id=5356309#5356479)

The other scary bit is that the 100x is toxic to humans, and that they cannot add any more drug to the 1000x because they've reached the limits of solubility.

</comment><comment><USER3> Video from the article: [https://www.youtube.com/watch?v=plVk4NVIUh8](https://www.youtube.com/watch?v=plVk4NVIUh8)

Fairly frightening.

<comment><USER4> Extremely frightening. Took just 11 days to mutate to an antibiotic resistant strain at 1000x concentration from zero resistance.

<comment><USER5> Haven't read the paper yet. But I expect to see a control where they plate the same starter culture _directly_ on each log scale antibiotic concentration (1,10,100,1000) to see if it contained resistant bacteria from the get go. Thus testing if resistant mutants were always present in a population or they arise _and_ are selected for by evolutionary process.

It is the _origin_ of mutants that is the more interesting question.

<comment><USER6> The video shows mutations in real time as bacteria grow or fail to grow in various places. [https://www.youtube.com/watch?v=plVk4NVIUh8](https://www.youtube.com/watch?v=plVk4NVIUh8)

It's more a demonstration than experiment, but visually it's just really striking.

</comment></comment></comment></comment><comment><USER7> I am curious - Are the bacteria really "evolving" at each subsequent boundary? In the article/video, they specifically mention "mutations". That says to me, that the bacteria are literally experiencing mutations within their nucleotide pairs, that results in them becoming more resistant to the drug?

Couldn't it also be that among the initial population, there existed 1 (or more) very very strong bacteria? At each boundary, the weak ones are dying off (hence the pause in growth) while the strong ones continue to reproduce. Since they're strong, but few, you witness a lag in overall growth of the population which the article is saying is the "evolving" process, when really it's more of a filter process. Filtering the strong, from the weak, by progressively stronger antibiotic strands.

I guess ultimately I'm just wondering what they specifically mean by "evolve" and "mutation".

<comment><USER8> Even if the mutation was part of the original soup of bacteria, the process in the video still shows evolution. Either at time=0 or some point in the future, a strain of bacteria was more fit to survive and produce viable offspring than the others that died off in the presence of the antibiotic doses.

</comment></comment><comment><USER9> Love it. One question, does the bacteria once it has conquered the known world does it begin to traverse backwards into the previous sectors?

<comment><USER10> I'd guess not. In many cases, these sorts of mutations are maladaptive outside of that environment.

Put a polar bear in the tropics and it's not going to do so well - not just because it's going to overheat, but because all the energy spent growing that hair could've been better used on something else.

<comment><USER11> This concept is key. Growth in the presence of antibiotic in pure culture on agarose plates does not necessarily equal pathogenic potential. Every adaptation probably has a cost to the bacteria, and if you throw in the immune system and other competitive bacteria that may not be pathogenic, those 'super bacteria' may be less super. All that said, as a microbiologist, antibiotic resistance terrifies me, with the current economics of new drug development being as daunting as the technical challenges.

</comment></comment></comment><comment><USER12> I would love to see this done with various bacteria against other chemicals. For example, Bleach. Bleach denatures cells so in theory it would never happen but it would be an interesting experiment.

<comment><USER11> I'm not sure bleach would be that interesting. It's like asking deer to evolve resistance to hunters' rifle bullets--it's too steep an evolutionary step.

<comment><USER13> Is it though? Imagine a world in which the only agent of selection was hunters bullets. No sexual selection, no food shortage, nothing. In other words, an absolutely perfect deer breeding ground.

Place a billion deer in this environment and shoot them all. A few survive. Let numbers rise, and do it again.

Soon you start seeing deer with arteries and veins that are smaller, blood that clots faster. Maybe the deer themselves are smaller, or their internal organs are smaller but their muscles larger, fed by a larger number of smaller veins. Perhaps muscle density is higher to offer better protection. Bone and skull thickness increases.

Eventually you've got an animal with a small, very thick skull, with lots of angles to increase the likelihood of ricochet, a heart protected by layers of thick muscle and a reinforced, thickened ribcage. Veins and arteries are reduced in size so much that it's practically impossible to bleed out, immune system is in constant overdrive to fight infection, and the rest of the internal organs are either shrunken, duplicated, or hardened against piercing damage.

In any case, my point is, if we could set up an experiment with deer like we can with bacteria, I think it's likely that we'd be surprised at what's possible.

<comment><USER11> Well done on the deer analogy- I'm in over my head there. I appreciate and agree with your point, and think my original response was glib and not clear. Clearly, extremophilic archea have evolved to inhabit nearly every niche of the earth (Deinococcus radiodurans is a great example). The point I took from the video was not that bacteria are rapidly able to adapt to antibiotics, that's been known as long as antibiotics have existed, but the observation of the instant in time when a bug figures out one of those discrete changes and its offspring thrive. I believe the scale and breadth of adaptations required to observe evolution of meaningful resistance to a universal denaturant such as bleach would be prohibitive. Bleach destroys at the level of protein chemistry, where as antibiotics are specifically toxic to bacterial structures. The wholesale changes would be required of the organism, rather than discrete mutations in the ribosome, cell wall, or other mechanisms known to drive antibiotics resistance-probably what you can see changing in the video. My awkward comment was intended to say I don't think the scale and time frame of the video assay would not be amenable to the scale of the study for bleach resistance. You illustrate that same point in your comment. That said this is all knowable first-hand, as generating or isolating bacterial strains resistant to toxins is science one could do at home with probably less investment that homebrewing beer, although without the fancy movies.

<comment><USER14> Taking this discussion a step further: in the bullets/deer instance, you'd be more likely to evolve a primary lifeform that looked more like a tree or grass or slime-mold than a deer. That is, it either consists almost _entirely_ of bullet-stopping material (wood), or is so lightweight that bullets don't effectively transfer energy to it (grass), or the structure is entirely decentralised such that a bullet, or even a hail of bullets, cannot disrubt the systemic function of the organism -- it simply absorbs the projectiles and functions around them.

A chlorine adaptation, if possible, would be along similar but chemical lines -- you'd end up with a non-protein based chemistry, or something not affected by chlorine, or which could buffer it to extreme levels.

Differential resistance to bleach at low concentrations might be possible to breed for. That could be interesting. In a similarly horrifying sort of way.

</comment></comment></comment></comment></comment><comment><USER15> [http://john.je/hQYZ](http://john.je/hQYZ) anyone know what this huge white dot is?

Also, does that + this worry anyone else? [http://abcnews.go.com/Health/fda- gmo-mosquito-test-fight-zik...](http://abcnews.go.com/Health/fda-gmo-mosquito- test-fight-zika/story?id=41143198)

<comment><USER16> Possibly a contamination. The article mentions they had to use lots of bleach to prevent outside contaminants.

</comment></comment><comment><USER17> This brings to mind how quantity will always beat one super power.

Example one bee will not kill a large predator but a swarm will.

One termite is joke but thousands will bring down a house.

I suspect one antibiotic will never beat bacteria in the long run. Looks to me like it's a never ending battle. I hear about the post antibiotic era like we had won the war at one time. What we won was a battle in a never ending war.

We hear about technology fixing all and jobs ending. Here's an area where there will always be a need for research and solutions.

</comment><comment><USER18> This reflects the importance of the dosage and duration when taking antibiotics.

This video shows hormesis[1] at its best: How bacteria is able to develop resistance over an increasing dose of antibiotic. I doubt that they would have been able to survive when exposed from 0 to x1000.

[1] [http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2248601/](http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2248601/)

<comment><USER2> > I doubt that they would have been able to survive when exposed from 0 to > x1000.

But neither would the patient.

<comment><USER18> The clinical dosage is made just for this: Kill the bacteria; don't kill the host

</comment></comment></comment><comment><USER19> I'm now worried about what they did to dispose of the central section.

<comment><USER20> Those are likely easily killable by other antibiotics than the one used.

<comment><USER21> Or just use bleach.

</comment></comment></comment><comment><USER22> Wow. 11 days to develop antibiotic resistance.

<comment><USER23> No, more like 2 days, 11 days was 1000x.

</comment></comment><comment><USER24> Is it really that easy to create super bacteria? What stops one from using something like this as a weapon?

<comment><USER25> It is not that easy.

Mutation works both ways. You can also lose something very fast, if it's no longer needed (basic rule of evolution - "Use it or lose it").

<comment><USER26> Bacteria have a solution to that too though with the use of mobile genetic elements called plasmids. So the genetics of something can float in the population with locality to its relevance. Most antibiotic resistant bacteria in hospitals get their resistance from ground dwelling bacteria people walk in with their shoes.

</comment></comment></comment><comment><USER27> @ISIS</comment>


What are the safest sources of energy? - <AUTHOR> https://ourworldindata.org/safest-sources-of-energy <comment><USER2> I would like that people would look at this kind of numbers and agree on the simple fact that burning fuels that release air pollution is bad and we should have a steady plan on how to phase it out and ban the practice. Regardless if people favor nuclear or renewable, we should all agree that coal, oil and gas do not belong in the energy grid.

Existing power plants that use fossil fuels should be phased out and new ones should not be legal to build. Pipelines for gas should not be built. If you don't want nuclear, build the battery and the renewable to fill it. If you don't want to build the battery, build nuclear. If you don't want the risk of nuclear disasters, accept the variability of renewable. Don't want to accept the variability of renewable, build nuclear.

The contention between renewable and nuclear can be good, but only in finding which one is safest and cheapest in a post fossil fuel energy grid. As long fossil fuels continue to be allowed the contention mostly serve to split the movement and pit the nuclear and renewable people against each other rather than against our main problem of greenhouse gas emissions and air pollution.

<comment><USER3> "we should all agree that coal, oil and gas do not belong in the energy grid." \- except fossil fuels are cheap, reliable, and energy dense. People want abundant energy to live developed lives, so until you can improve on these areas with the alternatives, it's always going to be contentious. Whatever the energy source, it needs to power 10B people with western living standards.

</comment></comment><comment><USER4> The conclusion are heavily tainted by hypothesis about the amount of victims. Chernobyl upper estimate is 965,000, see [https://en.wikipedia.org/wiki/Chernobyl:_Consequences_of_the...](https://en.wikipedia.org/wiki/Chernobyl:_Consequences_of_the_Catastrophe_for_People_and_the_Environment)

Don't forget nuke hot waste, left as a gift for future generations. Officially 'managed', yet there is no exploited repository.

Add combustible dependency (not so much known uranium reserves, no mastered way to obtain it w/o mining, in a not-so-distant future some may have to wage war in order to obtain some...), and nuclear proliferation.

<comment><USER5> Check your sources for that Chernobyl estimate. It comes from the European Greens political party and includes victims of Soviet mismanagement.

The UN's reports on the effects of radiation (UNSCEAR) estimated 4000 future solid cancers (not deaths) and later dropped that estimate when the data didn't pan out.

Civil used nuclear fuel has never leaked and is not so dangerous after a few hundred years. Don't try to confuse us with the issue of weapons as those are separate programs which predated all municipal atomic power production.

<comment><USER4> > Check your sources for that Chernobyl estimate. It comes from the European > Greens

Nope. You may think to the TORCH report. This report is another one. Read [https://en.wikipedia.org/wiki/Chernobyl:_Consequences_of_the...](https://en.wikipedia.org/wiki/Chernobyl:_Consequences_of_the_Catastrophe_for_People_and_the_Environment#Authors)

Some think that the UN is always right and without any bias. I don't. That's exactly my point here: there is no consensual way to assess nuke effective victims.

Don't try to confuse us by pretending that a nuke civilian program doesn't help nations trying to build a nuclear weapon. That's the root of Iran's current pertinent project, and "Many UN and US agencies warn that building more nuclear reactors unavoidably increases nuclear proliferation risks" (see [https://en.wikipedia.org/wiki/Dual- use_technology#Nuclear](https://en.wikipedia.org/wiki/Dual- use_technology#Nuclear) )

Don't try to confuse use with "not so dangerous after a few hundred years" while all pertinent experts and legislation, for example in France and the US, require that a waste repository must hold it safely for 1 million years, see [https://en.wikipedia.org/wiki/Yucca_Mountain_nuclear_waste_r...](https://en.wikipedia.org/wiki/Yucca_Mountain_nuclear_waste_repository#EPA's_rule)

<comment><USER5> That report (Fairlie, Sumner 2006) was commissioned by the European Greens. If you clicked once to the Wikipedia reference you're citing you could see that as well as why they might have been selected to produce that report.

Civilian nuclear energy rarely results in a nuclear weapons program. Today IAEA monitoring is effective in preventing diversionary pathways and enforcing international nonproliferation obligations (even where the US is obligated to not use internationally sourced uranium to produce weapons tritium).

A legislature requiring a million year containment is far from an evaluation of the waste's toxicity. Otherwise you would be forced to talk about specific isotopes.

<comment><USER4> > That report (Fairlie, Sumner 2006)

Please reread my posts here, beginning with the very first. I was writing about another report, titled "Chernobyl: Consequences of the Catastrophe for People and the Environment", by Yablokov & Nesterenko. It was not authored by Fairlie. If you clicked once to the Wikipedia references I provided since my first post you could see that. Here it is, once again: [https://en.wikipedia.org/wiki/Chernobyl:_Consequences_of_the...](https://en.wikipedia.org/wiki/Chernobyl:_Consequences_of_the_Catastrophe_for_People_and_the_Environment)

You may think that European Greens reports aren't credible, however this is IMHO a very weak counter-argument, simply the classical ad hominem fallacy at work.

My argument here is that this "What are the safest sources of energy?" article contents is highly debatable because it builds upon debatable theories. If the Chernobyl disaster really caused abut 1 million deaths, as stated by pertinent scientists in the aforementioned report, then the article's conclusions should be very different.

> Civilian nuclear energy rarely results in a nuclear weapons program

Iranian and North-Korean nuke weapons programs benefited massively from their civilian reactors, and this is widely documented ( see for example [https://isis-online.org/publications/dprk/dprkplutonium.pdf](https://isis- online.org/publications/dprk/dprkplutonium.pdf) )

Stating that the IAEA, which is an UN agency, has the power to prevent anything is just an opinion. Nearly all nations, small or huge, routinely neglect UN injonctions without any consequence.

> A legislature requiring a million year containment is far from an evaluation > of the waste's toxicity.

This is an opinion. I, for one, cannot see any other reason for those legal dispositions. Actions aiming at keeping a repository sealed for 1 million years cost more than those necessary to keep it for "a few" centuries, this was a deliberate decision.

The Japanese don't seem so happy with dispersed fuel: [https://en.wikipedia.org/wiki/Fukushima_disaster_cleanup](https://en.wikipedia.org/wiki/Fukushima_disaster_cleanup)

</comment></comment></comment></comment></comment><comment><USER6> What people (including here) tend to whitewash with nuclear is the waste. The radioactive waste that takes centuries or millenia to neutralize. Yes, it's kept in concrete bunkers underground and stuff, but no one can guarantee structural integrity of those silos over centuries. An earthquake might hit. A strain of concrete-digesting bacteria might eat through the walls. A war might break out, or simply terrorists. Ultimately, nuclear power contains an inherent and impossible to calculate, but quite real, environmental risk. And it's directed not at us, but at future generations who might have to deal with the cancer and toxicity caused by today's nuclear power. So no, I'm sorry, but nuclear _fission_ is not clean.

<comment><USER7> Nobody said that nuclear fission is clean, and nobody with even a bit of knowledge about it claims it is. Instead, what it is is CLEANER than fossil fuels and so forth, and this makes a huge difference.

Furthermore, your scenarios for nuclear waste leaking, while not impossible, are absurdly implausible if even a modicum of responsible engineering is applied to containing waste byproducts of nuclear fission. For one thing, this is definitely possible; the world is full of highly vital but very dangerous materials that are stored quite adequately, and it's also full of critical infrastructure whose structural integrity can't be absolutely 100% guaranteed either but which is often used for decades to improve human society in some way with few to no problems. Likewise for nuclear fission. The precautionary principle you take to extremes is absurd. Proper storage can be done and even improved enormously.

Secondly, the combined storage needs of all nuclear waste from every plant operating everywhere in the world for decades to come are minuscule compared to the availability of good, firmly sealable sites for doing this and compared to the sheer amount of waste tonnage created by fossil fuels and even by the repeat manufacture of long lasting batteries for certain renewable energy sources, if we want to get nitpicky. You're talking about one very small real estate/ecological footprint relative to energy output created with nuclear fission.

Thirdly, all of the above can be improved even further with moderate advances in how nuclear fission is produced. Even with today's more modern reactors, over 96% of already-used fissile material is recycled back into uranium-based and MOX fuel. One other immediate possibility is breeder reactors, which can in fact use waste from older fission reactors to create more energy. They can run on U-238 and transuranic elements, which create the absolute majority of waste byproduct in most current reactors. That's one exceptionally plausible solution to a part of the waste storage problem. Other even better solutions are also possible within reasonable development time frames.

In essence, your argument is somewhat similar to saying that nobody should ever use a microwave oven even while starving because there's always the very unlikely but not entirely impossible chance that it might give them a brain tumor, somehow, and let's furthermore ignore all advances in microwave oven technology to make this even less likely than it barely was earlier..

</comment></comment><comment><USER8> This analysis ignores the death potentiality which is the thing that strikes fear in people with nuclear. Even if the given numbers are true, (note that the official deaths from Chernobyl are 31 but the upper estimates are 93,000 - according to HBO), solar has the death potentiality for a few more people to fall off a roof, a battery to explode etc. These would be single digit fatalities if at all fatal.

The death potentiality of a Chernobyl/ Fukishima etc could reach the hundreds of thousands or more. The likelihood of this is probably very low, but non- zero. The likelihood of solar or wind having a catastrophic fatality event (that affected uninvolved civilians) is zero.

Given this, if all other things are equal, renewables are the favourable choice.

<comment><USER5> Remember that at Fukushima's twin plants 9 reactors were vulnerable and only 3 were lost.

Then the entire world put their nuclear energy under the microscope. South Korea discovered a parts testing scam. The US demanded more tests for the AP1000 design and eventually bankrupted Toshiba (thanks Jaczko). The US industry also designed a process for responding to beyond design basis accidents: FLEX response.

With renewables all things are not equal because the materials cost is dozens of times that of nuclear (IEA, Material Efficiency in Clean Energy Transitions) and the true cost to decarbonize is many times the naive capacity of wind and solar alone (Caldiera 2018, Geophysical constraints on the reliability of solar and wind power in the United States).

<comment><USER8> Of course all other things are not equal. Eg. Political capital required for deployment is not equal. Economics of scale is not equal. Cost per MW is not equal. Distribution of power is not equal. The things you have said are not equal. I think you missed the point of the "if".

</comment></comment></comment><comment><USER9> They've updated the stats but the tone stills seems to remain from the old version. It's not quite caught up with the reality of modern renewables expanding greatly as their costs decline.

<comment><USER10> These are deaths per TwH, capacity expanding won't change that.

The one thing that will change the death rate is if the capacity reaches the point where peak production exceeds demand. (Remember, we have no practical means of storing large amounts of electricity, the closest we have wastes at least 1/3 of it.) The thing is the deaths are from construction and maintenance, not operation, and thus go with nameplate capacity, not power generated.

</comment></comment><comment><USER11> Sunlight?</comment>


Relation between alcohol consumption in midlife and dementia in late life - <AUTHOR> https://www.bmj.com/content/362/bmj.k3164 <comment><USER2> >Abstainers were mainly women, had lower education and physical activity, were obese, and had a higher prevalence of cardiometabolic risk factors, all associated with an increased risk of dementia,11,12 which could explain the differences; however, adjustment for confounding factors did not alter the findings.

This is why interactive data visualization is so important. People need to be able to adjust the results of data to fit them, otherwise the margin of error and deviation from the "average" will be so great, findings are virtually useless to an individual.

<comment><USER3> > _however, adjustment for confounding factors did not alter the findings._

Let me guess: adjusting for confounding factors means throwing away most of the data, so that all that remains is a small group of abstainers and non- abstainers who are similar in all regards except for the abstinence.

Problem is, there may be more than one way to do that, with different results; then it's possible to choose a way of reducing the data to fit the desired hypothesis.

The only honest way to fix a confounding bias in the data is to re-do the study with a properly randomized sample of subjects.

<comment><USER4> Are you seriously suggesting a study in which people are randomly assigned people to drinking conditions for decades? That is perposterous.

Edit: To be clear, assignment to drinking conditions and following them over decades is unrealistic, would have problems with participant compliance, and is probably unethical.

<comment><USER5> I recently saw a study where adults were assigned to drink 1 drink per day or 0 drinks per day, for years, with the drinks subsidized.

</comment></comment></comment></comment><comment><USER6> Can anyone tell if this study avoids the "sick quitter" problem? ([https://www.vox.com/2018/4/24/17242720/alcohol-health- risks-...](https://www.vox.com/2018/4/24/17242720/alcohol-health-risks-facts))

<comment><USER7> See also: "sick non-exerciser". There's never enough discussion of correlation vs causation in these types of studies.

<comment><USER8> Also makes you wonder if some of those wine/none-wine-alcohol effects are really female/male effects.

<comment><USER9> There are also class and ethnic biases - wine drinkers are disproportionately college-educated and caucasian.

<comment><USER8> ...reading the fulltext now. They were selected from among middle-aged civil servants in London in the late 80s/early 90s so the sample is way more homogeneous than the total population, certainly if the U.S. is what you're thinking of.

<comment><USER10> In London...

Polluted London, Leaded car fuel London

</comment></comment></comment></comment></comment></comment><comment><USER8> "Abstinence from alcohol in midlife, long term abstinence, and decrease in consumption were associated with a significantly higher risk of dementia of 45%, 67%, and 50%, respectively, compared with consumption of 1-14 units/week, but only among participants who reported abstinence from wine."

I don't get that sentence. Doesn't abstinence from alcohol always imply abstinence from wine? Or is it saying that drinking 1-14 units/wk only lowers your risk compared to being abstinent if some of that consumption comes in the form of wine?

<comment><USER11> The next paragraph follows up a bit, the phrasing is odd but it helps clear up that the tenuous link is wine/wine components.

>The most intriguing finding from this study was the significantly increased risk of dementia among abstainers, including long term abstainers and participants who became abstainers, and that association was only present in those who abstained from wine.

<comment><USER3> Doesn't clear up anything. A person who does not abstain from wine is not an alcohol abstainer.

Among alcohol abstainers, there is no special category of those who abstain from wine; logically, they all must.

A: "I don't play sports"

B: "Which ones don't you play in particular?"

A: "Tennis."

B: "Ah too bad; the one I particularly don't play is soccer."

A: "I guess we won't be enjoying our non-play of sports together then. Your avoidance of soccer requires the lack of a big field and complete absence of half a dozen other players so that a team is not accidentally formed; whereas my aversion toward tennis requires that there be no court or racquets."

<comment><USER12> Jean-Paul Sartre is sitting at a French cafe, revising his draft of Being and Nothingness. He says to the waitress, "I'd like a cup of coffee, please, with no cream." The waitress replies, "I'm sorry, Monsieur, but we're out of cream. How about with no milk?"

<comment><USER13> Descartes is sitting across the table. The waitress asks him if he would be having some wine.

He replies. "I think, therefore I am."

</comment></comment></comment></comment></comment><comment><USER14> > Abstainers were mainly women, had lower education and physical activity, > were obese, and had a higher prevalence of cardiometabolic risk factors, all > associated with an increased risk of dementia

Well, pretty hard to draw conclusions from this study then.

</comment><comment><AUTHOR> Zero and heavy alcohol consumption could both be side-effects of isolation. Isolation is associated with dementia as a cause or an effect

</comment><comment> jf- My first thought is a relationship with glutamate excitotoxicity. Fronto- temporal dementia is known to be related to glutamate. If that's lumped in as part of the dementia cohort that may help explain the result.

<comment><USER15> Probably not a large factor because the prevalence of frontiers-temporal dementia is very small compared to vascular, Alzheimer's, Parkinson's. Anecdotally I see it in less than 1% of dementia patients.

Incidence of FTD is around 2.7-4.1 per 100,000 people.

Incidence for Alzheimer's is estimated to be roughly 10.5 per 1000

So although it's a good thought to have about the correlation, even if 100% of FTD cases were caused by that mechanism I don't think you'd see the difference they saw in the study.

Sources: [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3932112/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3932112/)

[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3405821/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3405821/)

<comment> jf- If I remember correctly, the mechanism underlying the glutamate toxicity is mutant SOD, which is made as a response to oxidative stress. The glutamate is simply an excitory stimulus that makes free radicals which need to be mopped up by something. Could be that other proteinopathies are a similar reaction to oxidative stress, and something that promotes GABA, such as alcohol, has a beneficial effect. But of course I'm only speculating.

<comment><USER15> I'm not knowledgeable enough about the biology to really add much to what you said there either, even though I deal with the end results.

Systems biology is one of those areas where I think AI will make a huge difference in the future. If you are interested in some thoughts on this listen to the first hour and a half talk by Craig Mundie (you can skip first 20 minutes of intro by Collins) of this recent NIH videocast on AI in medicine:

[https://videocast.nih.gov/summary.asp?live=28053&bhcp=1](https://videocast.nih.gov/summary.asp?live=28053&bhcp=1)

</comment></comment></comment></comment><comment><USER16> I post it again:

The Truth We Won't Admit: Drinking Is Healthy

[https://psmag.com/social-justice/truth-wont-admit- drinking-h...](https://psmag.com/social-justice/truth-wont-admit-drinking- healthy-87891)

Super smart guy by the way.

I am not sure why this gets downvoted. You may look up who this guy actually is: [https://en.wikipedia.org/wiki/Stanton_Peele](https://en.wikipedia.org/wiki/Stanton_Peele)

<comment><USER17> In light of this piece I'm curious about how countries with large sober populations (majority Muslim countries?) compare to others while accounting for other factors

<comment><USER18> > countries with large sober populations (majority Muslim countries?)

Closet drinkers. Pay enough money and you can get alcohol everywhere, including booze parties in the midst of Teheran. It has been covered e.g. here: [https://www.independent.co.uk/news/world/middle- east/drunk-i...](https://www.independent.co.uk/news/world/middle-east/drunk- in-tehran-the-islamic-state-s-secret-party-scene-9217419.html)

<comment><USER19> Reminds me of an Iranian friend I had. We were talking once about weddings in different cultures, and I asked her about Iranian weddings. She laughed and told me that despite the ban on alcohol, every man at an Iranian wedding ended up drunk "somehow".

</comment></comment></comment></comment><comment><USER8> One more thing that comes to mind: So they're comparing people who drink 14 units/week (one beer a day) versus people who drink more than one beer a day. Are the differences in the effects observed really dominated by the presence of people in that second group who drink a second beer and then stop their drinking for the day, or by the presence in that group of really excessive drinkers.

<comment><USER20> 14 units per week is two drinks a day.

<comment><USER20> Oh, sorry, just saw explanation below. In the US these studies equate 1 unit = 1 glass of wine or 1 beer, I could swear.

<comment><USER21> That's what a lot of sources in the US say, but, when they say, "drink", they mean "standard drink", which is this quasi-mythological beverage that one never encounters in real life.

I honestly think that it's negligent on the part of public health folks to continue the practice. Saying "Drinking more than 2 drinks in X time will cause you to be legally impaired" is actively encouraging people to unwittingly drive drunk in a culture when a typical ABV for beer is about twice what it was when those standard were originally calculated, and non- highball cocktails typically contain at least two shots of liquor.

"Unit" is so much better a term.

<comment><USER22> > when they say, "drink", they mean "standard drink", which is this quasi- > mythological beverage that one never encounters in real life.

I encounter 12oz bottles and cans of 5% abv beer literally every day

<comment><USER23> A 12 oz is .34 L, which at 5% would be 1.7 units of alcohol — rather different than a single unit.

<comment><USER24> In the US, "units of alcohol" are not a thing or part of the government recommendations.

One standard drink in the US is tied to 12oz of 5% beer (or it's equivalents in wine/spirits), _not_ the UK definition of a "unit" of alcohol.

When there are US health recommendations made, they are referring to standard drinks.

</comment></comment></comment></comment></comment></comment></comment><comment><USER25> Is this all related to sleep quality? Increased alcohol consumption decreases sleep quality, decreased sleep quality increases dementia risk, therefore increased alcohol consumption increases dementia risk.

<comment><USER26> The study is suggesting the opposite relationship - that decreased wine consumption _increases_ the risk of developing dementia

<comment><USER13> It's suggesting both. Low and high consumption increase the risk. For the high consumers, impaired sleep might be a thing.

</comment></comment></comment><comment><USER27> Who funded this?

</comment><comment><USER28> I'd like to see the probability changes,not just as percent change but as decimal values. The problem with reporting 17% this and 67% that is that even with a 67% increase in one group it could still be less than the 17% of another. This could help distinguishing things that are less bad vs being positive depending on where it falls in the p-range.

</comment><comment><USER29> So what corresponds to one unit of alcohol? A glass of wine?

<comment><USER8> It's a british thing. Drink manufacturers in the UK are obliged to declare the total amount of alcohol that's in the bottle using a "units" system, where half a litre of beer at 4% equates to roughly 2 units. So 14 units per week is a bottle of beer a day.

[https://www.drinkaware.co.uk/alcohol-facts/alcoholic- drinks-...](https://www.drinkaware.co.uk/alcohol-facts/alcoholic-drinks- units/what-is-an-alcohol-unit/)

<comment><USER29> Thank for the link!

</comment></comment></comment><comment><USER30> Forfeiting beer and whiskey? No thanks. Total digression, but does anyone here know of any drugs that cause neurogenesis? I speculate shrooms and acid might, but maybe I'm just delusional..

<comment><USER31> > does anyone here know of any drugs that cause neurogenesis?

Tianeptine is fairly well known[1][2] for being able to prevent and/or reverse changes like hippocampal volume loss, which is commonly seen in untreated depression[3], chronic stress[4] and several other conditions.

7,8-Dihydroxyflavone[5] derivatives and/or prodrugs also look promising[6].

[1] [https://www.ncbi.nlm.nih.gov/pubmed/22047727](https://www.ncbi.nlm.nih.gov/pubmed/22047727)

[2] [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4034085/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4034085/)

[3] [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1557684/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1557684/)

[4] [https://www.nature.com/articles/srep29127](https://www.nature.com/articles/srep29127)

[5] [https://en.wikipedia.org/wiki/7,8-Dihydroxyflavone](https://en.wikipedia.org/wiki/7,8-Dihydroxyflavone)

[6] [https://pubs.acs.org/doi/abs/10.1021/jm101206p](https://pubs.acs.org/doi/abs/10.1021/jm101206p)

</comment></comment><comment><USER32> I wonder if these differences has something to do with the personality of drinkers? People who are drinking might be more aggressive and might also be phisically active or exercising more. Do we actually have any fundamental reason to believe if moderate alcohol might be okay?

</comment><comment><USER33> As a non-drinker myself, I think this might have a lot to do with lack of sleep.

</comment><comment><USER34> "moderation in all things", as usual, seems like sage advice.

<comment> S-E-P maybe not all things... but most things :)

<comment><USER35> My favorite phrasing of that is a quote that I think is from Oscar Wilde: "moderation in all things, including moderation."

<comment><USER34> and it's even got the virtue of being true.

</comment></comment></comment></comment><comment><USER36> I'd like to see a study about the relation between Zen meditation and dementia.

</comment><comment><USER37> TL;DR: Get polyphenols in your diet. Wine is an option for this but there are others.

<comment><USER38> My grandfather, a wine drinker all his life, suffered severe dementia in his final years. There is no magic bullet.

<comment><USER39> Anecdotal data is not evidence.

My grandfather smoked 2 packs a day starting when he was 11 till he was 97 and didn't get lung cancer.

<comment><USER4> It is evidence of N=1.

</comment></comment></comment></comment><comment><USER40> > consuming large amounts (>21-28 units/week) was associated with an increased > risk of dementia compared with light to moderate (7-21 units/week) > consumption.4

The idea that 21 units of alcohol per week is _moderate_ and also _heavy_ drinking is.... preposterous.

Consider: drinking alcohol (ethanol) is a Group 1 carcinogen.[1] There is _no level of alcohol consumption that is safe_.

21 units of alcohol per week should always be considered _heavy drinking_.

1\. [https://www.cancer.org/cancer/cancer-causes/general- info/kno...](https://www.cancer.org/cancer/cancer-causes/general-info/known- and-probable-human-carcinogens.html)

<comment><USER41> Alcohol is a solvent. It dissolves stuff. Sometimes that is helpful in the workshop where you can see what you are doing. The same can't be said about inside your own head even though our ancestors have been experimenting for millennia.

Anyone done comparison studies with the Muslim world?

<comment><USER42> Water is a solvent as well. In fact, it dissolves more substances than any other liquid on earth. What is your point?

<comment><USER13> Not only that, but water has the highest pH of any acid!</comment></comment></comment></comment>


A Detailed Five Step Twitter Scaling Plan - <AUTHOR> http://whydoeseverythingsuck.com/2008/05/detailed-five-step-twitter-scaling-plan.html <comment><USER2> Paying attention to half-baked advice like this is half the reason Twitter is fucked.

</comment><comment><USER3> The suggested plan seems reasonable. Yes, if you denormalise users inbound and outbound messages then you store the data twice. Yes, shards give almost limitless scalability. However, could it be that during peak load, the number of messages to be written plus indexes to be maintained exceeds the total available disk seek operations?

<comment><USER4> So shard more, or get more disks, or get flash or whatever. (Yes, I don't know what I'm talking about.)

<comment><USER3> > So shard more, or get more disks, or get flash

Your intuition is excellent. These are all valid techniques to alleviate disk seek limitations. They are likely to be successful. Unfortunately, they're expensive options.

You can partially overcome disk seek limitations by performing database batch inserts. So, rather than inserting messages indiviually and updating indexes for each message, you insert 100 messages and perform less disk seeks updating the indexes for each batch. Unfortunately, it can be hard to reliably merge data into suitable batches.

<comment><USER4> Hank's proposed solution is expensive; we should just admit that up front. But is it more expensive than being down and fighting fires all the time?

<comment><USER3> The economics of downtime is a very important consideration. I read that three minutes of downtime reduces the value of a website by 1%. However, that may be a figure bandied by vendors of high-availability equipment. It is also generally acknowledged that high-availability is achieved through strict processes and sheer redundancy of hardware. Therefore, it gets exponentially more expensive to minimise downtime.

So, you've got two non-linear curves, cost and benefit. If you've got an exceptional team, a great architecture and good finances then getting 99.999% uptime should be easy. Of course, this assumes that you don't have unforeseen circumstances, glaring omissions in redundancy - or exponential growth and utilisation without a revenue stream.

Even with generous financing, exponential growth can be deadly. A small but sustained increment in load can be enough to cause a backlog in requests that never recovers. If you're growing fast then it can occur anywhere in your system at any time. I've been a DBA for a renderfarm with thousands of cores and this situation is stressing.

We've also had this situation while working on search. Thankfully, it occurred on a smaller scale and most thankfully it occurred before launch. We had two database servers, two app servers, no redundancy, on unreliable hardware. We didn't make much headway with efficiency improvements because long tests were likely to encounter hardware failure. It was demoralising.

This slowed the development and testing of a database failover feature in the database wrapper. Now this has been implemented, progress is much better. A test that previously took three hours now takes five minutes and we've had much more time to migrate to reliable hardware and introduce redundancy. We've also got a setup which can be used to test resilience to real modes of failure.

<comment><USER4> My guess is that Twitter's downtime is due to overload, not hardware failures. Thus a scalable system (even one with a high slope) reduces the overload/downtime problem to "buy more servers -- now!" instead of the "analyze bottleneck, rewrite code" loop that it sounds like Twitter is in now.

</comment></comment></comment></comment></comment></comment><comment><USER5> So wrong it's hard to know where to start...

<comment><USER6> Its fascinating funny how you are so smart you can't even deign to share your wisdom on this. If I am wrong, tell me where. Given that I have spent the last several years studying/developing distributed databases if I just don't know what I am doing I'd certainly like someone as smart as you to tell me.

<comment><USER7> Hank, your design is so high level as to be almost useless to anyone who'd actually benefit from a proposed design. It's not clear what issues you feel Twitter has, or how exactly this architecture would solve them. Usually your blog posts are more cooked than this one. I'm a regular reader, and at first I honestly thought your post was satirical.

As I read your design, one of the biggest problems is that to build up the infrastructure I think (and infer based of my experience with designing these kinds of systems) you are describing is that it's a massive engineering effort in and of itself. You basically end up rewriting a realtime-optimized BigTable or HBase, and that's much to much to expect of Twitter's small engineering team.

People seem to forget that scalability is a tradeoff, like any other aspect of a service. You devote an amount of resources to the problem that makes sense to your business. Despite twitter's downtimes, people don't seem to be leaving the service, despite several competitors. The service is down, but it isn't down so much that it's unusable.

For a site that's grown at such a rapid pace and has such a small engineering team, I think Twitter's scaling plan is probably very reasonable. They're growing their capacity at a rate they can afford, and a rate that they know will retain most of their userbase.

<comment><USER6> Well perhaps its a matter of staring at something so long it becomes simple. But I really don't think what I am suggesting is that hard. The main thing that requires some thought is shard splitting. That is not a big piece of code, but it does admittedly take some thought to get right. Aside from that everything else is provided out of the box by someone else like amazon web services or terracotta. I am not sure how I could have been more precise without source code.

It is certainly reasonable to suggest that Twitter is good enough as it is because people still use it, though the grumbling in the market suggests that that may not be something they can bank on forever.

<comment><USER7> One thing you don't address: where do messages go while a resource is self- splitting? How much redundancy do you build in to prevent this from being a problem? How much backlog do you expect to handle?

And have you checked latency serving out of EC2? Our experience is that the connections are fairly fast but the latency establishing the connection is significant, especially from the west coast where twitter is based.

<comment><USER6> I addressed this in another answer here but happy to do it again. The way shard splitting works is that the initial shard keeps working while the new shard is being built. During this time, all messages to the old shard are written to the old shard _and_ the new shard, so, unless I don't understand your question I dont see there being a backlog.

Regarding EC2, latency isnt really an issue because Twitter is far from real- time. That said, haven't really noticed any problems with EC2 connection latency, but we are not live yet so I would defer to you on that.

</comment></comment></comment></comment></comment></comment><comment><USER8> His approach isn't so good, as it creates a copy for the same message sent to multiple users.

Better safe the messages in a central store by id and only write the ids to the different pages.

<http://news.ycombinator.com/item?id=188080>

<comment><USER6> I considered this, but given that the messages are small and the primary issue is scaling not storage this, it does not seem to me is a good solution. The entirety of everything ever written on twitter is probably not big enough to worry about storage size. The issue is performance. By the way, this architecture is essentially how email works. All your inbound messages are stored in one place separate from outbound messages from the sender. This allows for infinite horizontal scaling.

</comment></comment><comment><USER9> These design techniques could very well make a nice impact on performance. Then again, they might not.

Why? They are proposals to solve a problem that _has not yet been defined_.

Fact is, you _don't know_ what the problem is.

So proposing a database solution to what could just as easily be a memory management or throughput problem is premature.

<comment><USER6> This is true. Though I can say that if one were building twitter and you didnt either have a design like the one I suggested, or a design with some kind of distributed caching then you are going to have exactly the kinds of scaling problems they have had. In other words if you use tradition techniques for something like twitter you are screwed. However you are absolutely right that (as I said in my piece) they may already, for example have thought of all of this and either implemented or dismissed it because they have a better design, and I have no way of knowing.

<comment><USER2> This isn't true. You don't need a distributed sharded setup in order to scale. (You probably do if you are limiting yourself to MySQL) I built financial applications way back in the day that had a lot more reads and writes than twitter, and we just used ONE gigantic, super expensive database server.

</comment></comment></comment><comment><USER10> Hank, good article, and good defense of your article here on HN. Regarding the knee-jerk negative responses you've received here, I can only say that you are a more patient man than I. Best of luck with your current project.

</comment><comment><USER11> This has been solved many times, many years ago. It's not a hard problem. A one step scaling plan would be "write it properly this time".

<comment><USER12> many things are easier said than done.

<comment><USER11> Of course. But there are solid examples from web1.0 and before that did more than twitter, and scaled to more users. Twitter is pretty simple in terms of functionality.

<comment><USER12> climbing Mt Everest/K2 has been done many times already, but it's still hard; and not something taken lightly

I just don't like gloating on someone else's mistakes and failures (essentially kicking someone who's already on the ground), especially when I'll probably have my own set of spectacular f-ups to deal with related to my own startup

</comment></comment></comment></comment><comment><USER13> This is post is little more than link bait (and I guess I'm falling for it by commenting).

<comment><USER6> With all due respect andrew why dont you share your technical analysis of what exactly I am saying that is wrong here. Btw, have you ever actually _worked_ on any database scaling problems? Just checking.

<comment><USER5> I have. I have managed systems that handle millions of clicks a day in databases and billions of dynamic (PHP) pageviews on a daily basis.

I am currently managing a system that serves over 100,000 DNS queries per second, each of which is dynamically evaluated as to how we respond to it. And each of which is logged, amounting to over 7,000,000,000 log lines a day, all which get processed, parsed and in many cases handed over to a database store. Yep, we're dealing with BILLIONS of rows of MySQL per day.

<comment><USER14> Do you have anything online about your architecture? I think it'd be interesting to see how those 100k queries per second get served.

Hey thanks for OpenDNS by the way, I'm a long time user, and I love it.

<comment><USER5> I'll be speaking about it for the first time at the Velocity Conference in June. I'll have slides available.

</comment></comment></comment></comment></comment><comment><USER15> imho, it's rails. rails (and any other ruby framework) is not suited for a real-time communication platform like twitter.

also you forgot about messaging queues.

<comment><USER7> Why would you say that? It's not like the Ruby code is handling that many messages. Even Rails sites don't use ruby for their concurrency and messaging. They push down to a database or to another concurrency level like ActiveMQ. Above them lives another piece of code or hardware to do load balancing.

This isn't even about Ruby, it's about the Rails architecture.</comment></comment>


Show HN: Publish and consume numbers and/or number streams - <AUTHOR> http://www.nnums.com/home

<comment><AUTHOR> The concept here is that every number stream has it's own web page.

Number streams can be updated by web requests, by hand, or using functions. Number streams can be created from other number streams or by automated scraping via xpath.

You can aggregate and follow number streams. You can also create email based alerts for when the streams cross a threshold.

Copy and paste snippets are given on each page to make it easy to follow numbers using Python, Go, Pearl, Ruby, PHP, etc. Numbers can be automatically updated from or published to Google Sheets using the same copy-paste mechanism.</comment>


Being bi-polar. - <AUTHOR> http://www.hell-and-back.net/

<comment><AUTHOR> Not sure if it's ok to comment on my own submission. I'm new to HN and I'm just not sure of the rules.

The site attached is my site and I'm hoping to share my experiences with mental disorder as way to help others with similar distress (even help myself). Please leave some comments here or on the site. I'm interested in hearing other's thoughts on my writings.

Regards</comment>


Your chances of dying - <AUTHOR> http://www.besthealthdegrees.com/health-risks/ <comment><AUTHOR> I find the switching between units makes comparison of risks here confusing. For example, 1 in 2.2 million _participants_ for Snowboarding, 1 in 1750 _annually_ for Mountain Climbing, and 100 deaths in 1 million _exposure days_ for Mountaineering in Mt. Mckinley National Park.

<comment><USER2> I also found this unit switching to make it difficult to make comparisons, even when regarding similar groups. The author could have converted units while staying true to the source materials.</comment></comment>


Twitter's GIF hack - <AUTHOR> http://blog.embed.ly/post/89265229166/what-twitter-isnt-telling-you-about-gifs <comment><USER2> This is not true:

"A GIF is literally a sequence of independent images squeezed into the same file. An mp4 video can take advantage of all kinds of fancy compression techniques like keyframes and forward-predictive frames."

That's not why the mp4 is smaller. A GIF is not [just] independent images, you can have each frame reuse pixels from previous frames.

The mp4 is smaller because lossy jpeg compression is used on each frame, while the gif stores each frames losslessly.

This has implications from the predictive frames as well - the jpeg is lossy, so two almost similar parts of the images can be considered "the same", while the gif is not, so they must be identical in order to compress that way, and the realities of video noise makes that unlikely.

<comment><USER3> Not quite true yourself :).

GIFs store deltas, true, but they are still raster images.

H.264 on the other hand contains specific techniques for compressing sequential frames, including things like recording only pixel motion for some frames. You can see it in those "corrupt movies" gifs (which on twitter would be mp4s... talk about irony) where you take a clip and remove some keyframes from it - then transformations are applied on the wrong blocks and you get really weird things like someone's head splitting open and stuff flowing into each other.

Additionally keyframes in movies are usually compressed with even more loss than standard jpegs. In most cases only the Y channel is recorded at full resolution and the two colour channels - U and V - are recorded at half.

There is also motion-jpeg which really is literally a sequence of jpeg images.

<comment><USER4> Just a nitpick, JPEG always encodes the color channels at half resolution. It's amazing how difficult it is to notice this, though.

<comment><USER5> No, there are 4:4:4 and 4:2:2 modes in JPEG.

H.264 also defines such modes, but no consumer hardware decoders support them so they aren't commonly used.

<comment><USER4> My mistake, I must have been going off what's common versus what's allowed. Thanks for pointing it out.

<comment><USER6> Apple's jpeg animation hack used 4:4:4 so the blocks wouldn't interfere with each other. It's a neat hack, worth reading about if you haven't seen it yet: [https://docs.google.com/document/pub?id=1GWTMLjqQsQS45FWwqNG...](https://docs.google.com/document/pub?id=1GWTMLjqQsQS45FWwqNG9ztQTdGF48hQYpjQHR_d1WsI)

<comment><USER4> Holy moly. What a hack.

</comment></comment></comment></comment></comment></comment></comment><comment><USER7> Correct me if I'm wrong, but wasn't the whole reason gifs started proliferating on the net because people wanted to share short video loops, but didn't want to embed flash or video which may not load or play correctly in a user's browser? And now we are championing the conversion of those gifs back into video? Seems like a strange round-about way of doing things.

I forsee a future where all video clips on the net have been converted back and forth between gif and video so often that they all slowly merge into a single amorphous blob of greyish-brown pixels. Actually, now that I think about it, that would almost certainly be an improvement over the current situation.

<comment><USER8> I don't think gifs' recent surge in popularity has anything to do with technical issues like browser compatibility. They became popular because of artistic/aesthetic value and web culture. These features all differentiate gifs from _2010-mainstream_ forms of embedded video like Youtube:

      - starts playing automatically
      - loops seamlessly
      - never has sound
      - no logos or buttons like "share" and "embed"
      - no scrubber bar on the bottom
      - repeated instances of the same gif play back in lockstep
      - no frame around it
      - pixel-perfect control

All these features make it possible to create art that wouldn't work with embedded video. (Defining art broadly; captioned movie clips are included.) In the past few years, some creative people started making really good gifs that took advantage of these features. Then the trend spread through web culture. The next generation made gifs because "making gifs is what clever artistic people do on the internet".

It's always been easy to create a looped animation format that combines the feature list above with a better compression scheme. Now that gifs are so popular, someone recognized the need and made one.

IMO, the 256-color dithering was more of a necessary evil for most gif creators, although some took advantage of it. It looks nostalgic on 90s Gourard-shaded untextured computer graphics. But for movie clips, etc, I think many will be glad to get rid of it. I bet we'll see a sect of gif creators who think mp4s are not authentic while most people won't care.

Your last comment reminds me of Alvin Lucier's "I Am Sitting In A Room" (wiki/youtube). Someone repeats that idea with every lossy medium we invent. I've seen jpeg and vhs examples but I can't find the links right now.

<comment><USER9> I think your list of features is spot on, but I don't think their mainstream popularity had much to do with artistic expression. I'd include one other big feature:

       - They are dead simple to save (or link to) and drop into your own page/blog/comment.

and claim that GIFs are just really easy to share and view. They've offered a better experience both for post and viewing a short soundless clip than could be provided by an embedded Youtube player.

<comment><USER10> How about the fact that there is _zero_ advertising. IMO this is the number one piece of friction for videos (mainly YT) and the users don't want them for especially quick moments (a la Vine).

<comment><USER11> There's nothing really stopping people hosting GIFs from putting in advertising. Although it's true that I haven't seen examples of this happening.

</comment></comment></comment></comment></comment><comment><USER12> This article makes it sound like Twitter invented a whole new optimization, when they really just recycled a concept already in use by gfycat ([http://www.gfycat.com/](http://www.gfycat.com/)) and MediaCrush ([https://mediacru.sh/](https://mediacru.sh/)).

<comment><USER13> The latter being open source (I made it): [https://github.com/MediaCrush/MediaCrush](https://github.com/MediaCrush/MediaCrush)

</comment></comment><comment><USER14> I'm curious if anyone is noticed the flickering Loading icon when the .mp4 version loops? It only shows up for 50 ms, but seems kind of annoying. Or maybe it's just my machine?

Here's a cap: [http://imgur.com/2R84ImD](http://imgur.com/2R84ImD)

<comment><USER15> Yeah, I see it too. Very annoying.

<comment><USER16> Also annoying to have to allow javascript to see what is supposed to be an image.

</comment></comment></comment><comment><USER17> This is on a fully-patched RHEL6 workstation:

[http://i.imgur.com/NleqJTD.png](http://i.imgur.com/NleqJTD.png)

Another example of "use bleeding-edge tech or go fuck yourself" from the modern web.

<comment><USER18> Support for mp4 isn't bleeding-edge tech on other operating systems / distributions, unfortunately. It's a couple of years old in terms of being supported by Chrome; it's supported in Firefox as of last August.

At this point, desktop configurations that can't play mp4s are at risk of being considered "broken."

<comment><USER19> Is it really that difficult to supply a free format like WebM in addition to patent-encumbered H.264? If you only supply H.264, you're cutting out Firefox on OS X, Chromium, and Opera.

<comment><USER20> It does mean you need to transcode and store twice as many files, which can be a serious pain if you've got a number of different bitrate H.264 assets. It can be a big pain if your software assumes there'll only be a single media file. Not insurmountable but painful for small operations (and for large operations, where there may be a back-catalogue to worry about)

I'm with you in spirit, but in practice I think we can all understand why people often just go for H.264

<comment><USER21> This is a new feature launched by one of the biggest web brands there is, so presumably theres no back catalogue.

</comment></comment></comment></comment></comment><comment><USER13> I made a site that drove this innovation, MediaCrush. It's open source.

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

if you want to try to do this yourself, our code is a good reference.

[https://mediacru.sh](https://mediacru.sh)

<comment><USER22> Why did Gfycat win? I've always wondered.

<comment><USER23> I'd bet on UI and marketing.

The player is very unobtrusive and minimalist, and simple things like pronounceable random names probably appeal to the user.

Also, features that are well-known to heavy reddit users (such as easily resizeable videos) only helped with the word-of-mouth.

</comment></comment></comment><comment><USER24> "Videos allow Twitter to leverage the browser. This means play, pause, and seek, but also cool things like slow-motion. Think your GIF is funny now? Wait til you see it in slow motion."

Gifs have built in slow motion, it's called waiting for the 10mb file to download frame by frame upon initial play-through.

</comment><comment><USER25> Unfortunately the MP4 looks worse than the GIF, due to chroma compression in the YUV 420 colorspace. While each pixels luminance value is kept, the color information for a 4-pixel square is stored as a single CrCb pair, which is really obvious when you look at how the orange hat has artifacts against the blue background. Increasing the bitrate won't solve this either, since it's a limitation of the colorspace.

<comment><USER26> Or alternatively browsers could use non-terrible chroma upsampling algorithms.

[http://screenshotcomparison.com/comparison/79805](http://screenshotcomparison.com/comparison/79805)

<comment><USER27> Thank you! I was gonna post the exact same thing. Nice website, though.

I encoded the gif in 420 (subsampling), 422 and 444, having a nice quality with 444 with VLC, I embed the three different videos in a web page and when playing in my browser, they are all as bad as the twitter video! I thought that Firefox was using a standard library to play MP4?

<comment><USER26> Firefox uses the Windows-bundled decoder on Windows Vista or later. Chroma upsampling happens after decoding so it's the renderer's responsibility (Firefox, Chrome, VLC, madVR etc).

Depending on the webpage you uploaded them, the videos could be re-encoded (or VLC's options could be no-ops and the artifacts hidden when played back in VLC due to better chroma upsampling) hence the problem.

<comment><USER27> Okay, thanks for the explanation on the chroma upsampling! I use Linux but it should work all the same.

When I said that I embedded the videos in a web page, I wrote a small page from scratch to display them in my browser, locally, without any server. So no re-encoding. I think that VLC just has a better chroma upsampling.

</comment></comment></comment></comment></comment><comment><USER28> We've been doing that at my company on our mobile applications for a few years now. There is no reason to be shoving 5-10mb GIFs down a users throat on a mobile device. Not only does are MP4s smaller (file size), frames per second will be constant on all browsers, unlike GIF (although most browsers are supporting up to 50fps these days). Although outdated, you can read more about that here. [http://nullsleep.tumblr.com/post/16524517190/animated-gif- mi...](http://nullsleep.tumblr.com/post/16524517190/animated-gif-minimum- frame-delay-browser-compatibility)

I wrote a simple js lib for detecting the duration of a GIF for each browser. It was a fun weekend project. [https://github.com/rfrench/gify](https://github.com/rfrench/gify)

If webp gains more adoption, it's another alternative now that it supports animation.

</comment><comment><USER29> Haven't things like gfyCat been doing HTML5 video from GIF's for a while?

<comment><USER30> In a way they're doing it better. Twitter only seems to support MP4 whereas gfycat et al will deliver WEBM or MP4 based on the user's browser.

<comment><USER31> Agreed. MP4 doesn't work on Firefox (out of the box).

<comment><USER32> You should probably qualify that somehow, because MP4 works for me on Firefox (on OSX 10.9).

<comment><USER33> It does not work for me, too. FF30, OSX 10.9.3.

[https://www.evernote.com/shard/s19/sh/e81e070a-4e2e-4367-9eb...](https://www.evernote.com/shard/s19/sh/e81e070a-4e2e-4367-9eb1-83a7f6fe151f/42755f0246227bd75eb5e1099f857348/deep/0/About- This-Mac-and-Embedly-Blog,-What-Twitter-Isn't-Telling-You-About-GIFs--- Vimperator.png)

<comment><USER32> OSX 10.9.2 + FF30 here: [http://i.imgur.com/uTlQkg7.jpg](http://i.imgur.com/uTlQkg7.jpg)

<comment><USER34> Right click the video. It's probably Flash. Plays using Flash in Firefox on my machine.

OS X is the last platform where Firefox doesn't support H.264. They're working on it, but it doesn't seem to be landing soon.

</comment></comment></comment></comment></comment></comment></comment><comment><USER35> Much like what [http://gfycat.com/](http://gfycat.com/) do, then?

Interesting also that 4chan recently added looping, muted WebM videos for similar reasons.

</comment><comment><USER36> Is there a flash blocker solution that removes all traces of the page element rather than leave an ugly placeholder? It's going to be annoying to see this on Twitter from now on.

</comment><comment><USER37> So, what is an easy way to convert gifs to mp4? How did they do this. I run a small gif-sharing site and should probably do this.

<comment><USER38> I had a convoluted method using gifsicle to extract the frames and then encode as a stream of frames, but then sometime in the past year or so ffmpeg improved native gif support. This is what I use (the options are both for compatibility):

        ffmpeg -i foo.gif -pix_fmt yuv420p -vf crop=floor (in_w/2)*2:floor(in_h/2)*2 foo.mp4

Works for WebM just by changing the extension, too.

</comment></comment><comment><USER39> I think now would be a good time to introduce HTML5 videos to the feed, or gfycats. At least on certain browsers.

</comment><comment><USER40> It's annoying to an oldtimer, like me, that _animated_ gifs have now simply become _gifs_.

</comment><comment><USER41> This is why 4chan supports WebM videos now in addition to the traditional gifs.

</comment><comment><USER42> Can I skip the GIF and have Twitter just play an MP4 I upload ?

</comment><comment><USER43> The twitter "GIF" is a black box. gg

</comment><comment><USER44> Another option (for supporting browsers) is to use animated webp: [https://developers.google.com/speed/webp/faq#why_should_i_us...](https://developers.google.com/speed/webp/faq#why_should_i_use_animated_webp)

</comment><comment><USER45> GIFs indeed are bad for video (quality, size, no control, no sound, etc.) but in order for that to be really true, the site must allow embedding videos using the video tag (i.e. videos which people upload in proper video formats). Does Twitter allow it?

</comment><comment><USER46> So. Who was first. 4chan or twitter?

How long has twitter been doing this? Just out of curiousity.

(Yes I know 4chan doesn't convert but there was some talk that 4chan might be a major player in pushing webm forward. Is it even webm or x264? On mobile. Can't check right now.)

<comment><USER47> gfycat.com and others have been doing this for a while.

</comment></comment><comment><USER48> This is what I see on the page: [http://i.imgur.com/wFjEY8t.jpg](http://i.imgur.com/wFjEY8t.jpg)

I can understand why twitter is saving money on hosting these new "gifs"

</comment><comment><USER49> This is what Gfycat [http://gfycat.com/](http://gfycat.com/) is been doing since last year but as a service.

</comment><comment><USER50> The saddest part is that you can't add a zip to that gif and use twitter as a sharing platform.

cat x.zip >> y.gif and upload would have been nice ;)

<comment><USER51> Combined with twitter's link shortening, you could use this instead: [https://code.google.com/p/furl/](https://code.google.com/p/furl/)

</comment></comment><comment><USER52> Great, and we've lost the ability to save them to your computer, and to share them outside of twitter's ecosystem.

</comment><comment><USER53> I would think it's to avoid any traces of steganography... naaah I'm just kidding....

</comment><comment><USER54> Does anyone know what they are doing for the conversion? Any services out there do this?

</comment><comment><USER55> For me the main lesson here is that I should be more attentive and investigate. I remember noticing some un _gif_ fy vibe about animated clips on Twitter, but quickly dismissing the observation. Perhaps if my timeline contained a lot of GIFs I'd dig deeper, but it doesn't help feeling shallow.

</comment><comment><USER56> This is an automated fix. Animated GIFs are the hack!

</comment><comment><USER57> its like many other sites do it and its much better that way

</comment><comment><USER58> attn: reddit, please do this

</comment><comment><USER59> Hopefully this will contribute to the extinction of gifs.

</comment><comment><USER60> I had noticed that. Because of flashblock.

Yeah, a 20+ years file format doesn't do compression between frames, who would have thought...

<comment><USER2> Except that it does do that, the article is wrong.

As I wrote in a different comment the actual reason is lossy jpeg compression, not intra frame compression.

<comment><USER60> Aah you're right.

Yeah, for pictures jpeg is much better (and smaller) than gif.

Not to mention in several gifs they really reduce the quality to have a smaller file size</comment></comment></comment>


Chrome Developer Tools adds "Copy as cURL" - <AUTHOR> https://coderwall.com/p/-fdgoq

<comment><USER2> Does this work for streaming videos? The `open request in new tab`->`save`->`close original tab`->`stop new tab` process works, but is a bit long. Would be nice to just be able to cURL/save.</comment>


Stephen Colbert Interviews Neil deGrasse Tyson (2010) - <AUTHOR> http://www.youtube.com/watch?v=YXh9RQCvxmg <comment><AUTHOR> This is a very long interview but seriously worth it. Entertaining and enlightening.</comment>


Node.js production ships unmaintained version of v8 - <AUTHOR> https://code.google.com/p/v8/issues/detail?id=3692#c3

<comment><USER2> There is such a thing as "Node.js production"? It's still v0.10.33 - don't be too harsh, give it a few years.

</comment><comment><USER3> That seems... bad.

<comment><USER4> Did it seem bad a year ago? 2? 3? It's always been that way. 3 years ago, when ry was still on the project, it was only 30 days delta [0][1]. Joyent has chosen to increase the Technical Debt in order to increase overall Node Stability. Pick your poison.

[0] [https://github.com/v8/v8/tree/3.6.6](https://github.com/v8/v8/tree/3.6.6)

[1] [https://github.com/joyent/node/commit/0ba8f05a423df0e2ef53fc...](https://github.com/joyent/node/commit/0ba8f05a423df0e2ef53fcbc6e8c490d6bd06395)</comment></comment>


Designer eager to become Developer - <AUTHOR>

I have put together a few web pages (html,css,jQuery) but am very new to Web Development. I have only done front-end design. I am comfortable with Linux but don't know Apache or MySQL but am in the process of learning Rails as my framework. Will learning Rails be better then learning a LAMP stack for getting a website online? Or am I comparing apples and oranges? And what would be some different hosting options for each? <comment><USER2> Choice of language is pretty much a matter of comfort when you're first learning. The question is, do you want to be using Ruby/Rails or PHP/Wordpress/Codeigniter/etc. If you're just learning, you're going to _want_ to code in whatever language you choose. Just for reference, you can create backends for websites in Clojure, Java, Python, Haskell, go, JavaScript(node.js), etc as well.

I'd say use Ruby/Rails if you want to create webapps and PHP/etc if you want to create Wordpress sites. Someone more experienced than me in these languages can comment further.

Heroku.com supports Ruby and from using it with Clojure and node.js apps, I highly suggest this route even if you enjoy setting up your own servers. You can also use providers like Amazon EC2/Joyent/Rackspace and set up your own box to be either a LAMP stack or Ruby/Rails.

There is a long list of Databases to choose from these days, including: MySQL, PostgreSQL, Riak, CouchDB, MongoDB, Cassandra, etc.

Truly the answer you're looking for is "Just start somewhere". The amount of tech you can choose between is dizzying and you'll eventually get to a point where you can make your own decisions if you just keep hacking.

<comment><AUTHOR> Thanks for the great reply to start. I clearly am a little over my head and am always looking for the "right direction" to go and end up getting caught up in buzzwords. I only have a few web pages that I need hosted, so frameworks aside...would hosting options such as linode or rackspace be the best option?

<comment><USER2> Yes.

If you want to get into designer/developer mode for clients you are likely going to have to learn to host your own servers (note: I don't mean physically, I mean services like Rackspace, etc). If they're a couple static (ie: no server-side language) pages that won't get hit very often, you might use github's pages functionality.

I'd go with Rackspace over linode due to the great feedback I've heard about Rackspace, whereas I've heard relatively little about linode. Personally I use Heroku as they have a free tier that helps when just "getting stuff out there". The problem with Heroku is they don't have explicit support for PHP, so that could be an issue for you. If you're going to go after big client work, Amazon Web Services (EC2) familiarity is a nice checkbox to tick.

Remember a server is just a computer. If you can set it up to run on your computer, you can set it up to run on a server.

P.S. Get used to being in over your head. It's the fastest way to get up to speed, just learn how to swim underwater.

<comment><AUTHOR> I do want to be able to host my own servers..one day..as for now I think I will "just get this project out there". I think I've got enough Rails under my belt to get the few pages I need up, and Heroku's free-tier seems perfect to learn and practice on.

</comment></comment></comment></comment><comment><USER3> I'd say the stack to learn depends on what you want. Basically, the best bet for a job anywhere is knowing LAMP plus frontend (which you already can). I think rails/ruby is prolly going to be harder but if thats what you like then go for it :) As far as apache goes if you just want a job as a developer basically all you need to know is mod_rewrite aka regex, and some really basic other stuff like virtualhosts, etc that you can learn in a day. On the other hand SQL is going to be harder, learning "enough" shouldn't be a problem, but to know how to use joins,views,triggers,migrations , etc is something you should start on in tandem with your programming language. I know too many developers who don't concentrate enough on knowing/managing their data when this is always the heart of your application. As far as hosting goes, with LAMP you all you need is a nix machine somewhere, I'd suggest getting a linode (<http://www.linode.com/>). This also has the added bonus of great docs and you can try out and teach yourself everything on your own machine w/out crappy cpanel stuff.

Good luck!!

<comment><AUTHOR> Thanks! That's good to know about Apache. I haven't even had a chance to look into it thoroughly. Maybe I'll dive into it this weekend :) So if I want to get up and running quickly my best bet would be to grab a linode with a LAMP stack?

<comment><USER3> yep :) I'd suggest getting your linode with the distro you want, then going through one of these tutorials <http://library.linode.com/lamp-guides>. Also have a look at all the other docs on library.linode.com there really good and you can learn a lot.

Lastly, if you happen to decide to learn PHP instead of Ruby, I'd highly recommend starting out "the right way" with a framework like Symfony2 (<http://symfony.com/>) or Flow3 (<http://flow.typo3.org/>) that uses namespaces, good OOP techniques, ORM, and encourages / will teach good programming techniques. Also, have a look at composer (<http://getcomposer.org/>) - which is the modern PHP equivalent of Ruby Gems.

</comment></comment></comment><comment><USER4> A LAMP stack will be easier to deploy simply because pretty much any cheap hosting you get as a playground will support it out of the box. Rails is a little more tricky to deploy. That said, Ruby and Rails is, in my opinion, more fun than an equivalent in PHP (pure opinion though so don't let that colour _your_ experience).

I would suggest taking one bite at a time - find the easiest deployment possible for your chosen stack (if it's rails, then deploy some test projects to heroku). Learn to program a little before trying to jump in and do the Apache setup etc. Nothing is more frustrating than wanting to see your creation on-line but you just keep hitting your head against a brick wall because you can't deploy. I'll also put in a good word for webfaction for good cheap hosting that supports rails, django, and php very nicely without you having to do a lot of server admin - perfect for a playground.

<comment><USER5> I second that, if you're new to Rails you should definitely check out deployment with Heroku, they made an awesome job making it really smooth and they have great documentation on how to do it. Michael Hartl covers this exceptionally well on this section of his book: [http://ruby.railstutorial.org/ruby-on-rails-tutorial- book#se...](http://ruby.railstutorial.org/ruby-on-rails-tutorial-book#sec- deploying)

<comment><AUTHOR> Definitely a smooth install and setup for Heroku. Michael Hartl's tutorial is great. I've actually been going through it today!

</comment></comment></comment><comment><USER6> I would just begin to expand on your back-end skills. Since you have HTML/CSS/JQUERY under your belt. Continue to work on those, and also begin with a database (MySQL works fine), once you learn basic database-ing, then begin working on the controlling logic between the two. I would recommend PHP only because it's a quick language to learn and get busy with. This gives you a solid set of skills and a good view of the process. From there you can begin to enhance what you do with the two.

Nothing needs to be super-advanced, get down and dirty and learn quickly; more advanced work will come with time. As biscarch said 'just start somewhere'.

<comment><AUTHOR> Yeah, LAMP seems to be the best route to get up and going faster, I think I'll start with that. I need to be learning those DB and process skills to begin with, which makes taking the LAMP approach probably the best option. Thanks.

</comment></comment><comment><USER7> You have to decide what kind of developer you want to be. A hobbyist would probably go with the most out of the box stuff, so would use something like rails. You could be a specialist developer who only knows one framework and language. Or if you want to be a total pro you will want to learn all the frameworks because you are very adverse to your coworkers knowing anything you don't.

<comment><AUTHOR> I completely agree and I do want to be a total pro but am too spread out. I need to start focusing on certain aspects...maybe learn the ins-and-outs of a complete framework?..like Rails while continually learning more and more in- depth HTML, CSS, and JS? I guess my aim is to be a full-stack developer but am struggling finding my footing on the server-side of things.</comment></comment>


Airbnb to earn $183M in 2012 (I think) - <AUTHOR> http://postbarter.blogspot.de/2012/06/airbnb-to-earn-183m-in-2012-i-think.html <comment><USER2> Non-business travel obviously jumps up in the summer - it's a huge mistake to think that a growth curve encompassing summer bookings will continue at that same pace in the fall.

</comment><comment><USER3> Aside from first mover advantage, what is stopping copycats from moving in and starting a price war with Airbnb? If they are this profitable, that quickly, it should only be a matter of time before competitors crop up. One could argue that user acquisition is the barrier to entry, but just like the Groupon copycats, it'll be worth it for copycats to "buy" users to gain market share.

Airbnb has a great brand, great management, amazing infrastructure, et cetera, so I'm not suggesting that copying them will be easy. However, I think a lot of people that use the site are by definition budget conscious, or else they'd just get a hotel, so I could see both Hosts/Guests jumping ship to a less expensive option.

Curious what you guys think.

<comment><USER4> > Aside from first mover advantage, what is stopping copycats from moving in > and starting a price war with Airbnb?

First mover advantage is only part of the story. The network effect is already pretty powerful and only gets stronger. AirBNB has done all the work to polish the experience, and hosts are making money using the site. That's very sticky. On top of that, as a guest, you now know that there's nowhere you can go to get a bigger selection (which co-incidentally, gets bigger everyday) of reputable hosts. Same is true for hosts, with the added benefit that guests are insured.

> just like the Groupon copycats, it'll be worth it for copycats to "buy" > users to gain market share.

Whatever the copycats can pay, AirBnB can pay more, and even then, the hosts have no incentive to switch from AirBnB to something else. They might list elsewhere, but as long as more guests are coming through AirBnB, they wont cancel their AirBnB accounts.

Fundamentally - AirBnB enabled people to monetize something that lay fallow before. The thing that makes people switch wont be a lower transaction cost; it will be a greater chance of booking (and thus revenues).

<comment><USER3> > Whatever the copycats can pay, AirBnB can pay more

If AirBnB has to "pay" to defend market share, then this would be an example scenario of competitive pressure reducing margins.

Again, I think AirBnB is an amazing company and agree with all your points. Just curious what the competitive landscape will look like in one or two years.

<comment><USER5> Great points. I think Airbnb competition will emerge beyond the international copycats (Wimdu). Their biggest risk is other small startups picking apart niche markets within he greater accommodations vertical. Others have thrived like crashpadder (acquired by airbnb) or Onefinestay.

I think in two years you will see more Airbnb's in the accommodations marketplace competing on price and experience. The market has room for Marriott, and super8.

</comment></comment></comment></comment><comment><USER6> I'm not particularly knowledgable in this area, but shouldn't a revenue generating company with a $1B valuation be making more than that? 4X revenue is $732M

<comment><USER5> Valuation is based on the total addressable market for travel and other markets, not what they are booking today. If this growth continues their revenues will certainly justify the valuation even before moving into adjacent markets.

</comment></comment><comment><USER7> These numbers are so off that I had to log in to flag this post.

Airbnb's commission is 3%, not 13% as in the post. That makes a world of difference. The post also assumes an increasing growth rate in the number of rooms booked _and_ a substantial increase in the prices of rooms booked and in the average length of each stay.

Basically, this post is just some guy trying to bring people to his blog using Airbnb for free press and made up numbers to make it seem like he has something to say.

<comment><USER3> <http://www.airbnb.com/help/question/104>

"We charge guests a 6-12% service fee for every reservation booked, depending on the total of the reservation."

"Airbnb also charges hosts a 3% fee for every booking that is completed, which covers the cost of processing guest payments."

9 to 15% range and the author chose 13%

<comment><USER7> Payments collected on behalf of other parties (i.e., the payment fee) are not treated as revenue under GAAP. If AirBNB were to do such a thing, its auditor would refuse to sign off on its financial statements.

And, as I said, the post is assuming maximum commission on each reservation, with the length of each reservation increasing substantially from the year before. (To put it in comparison, it is like saying that Microsoft's revenue from Windows 8 will be $100 billion this year, assuming the best numbers for everything.)

<comment><USER3> His math is sound and he clearly states his underlying assumptions.

Using the recently published infographic, AirBnB revealed it did 5,000,000 nights in a 143 day period. Grossing this up by 365 days equals 12,750,000 nights projected for 2012 (5M / (143/365) = 12.8M).

This calculation implicitly assumes that the rate of bookings does not increase for the rest of 2012, which is probably not true looking at their impressive growth rate. The author backs out a 19% month-over-month historical growth rate using other statistics published in the same infographic. Using this rate of growth, he derives a projected 17.6M nights for 2012 versus the 12.75M above.

> with the length of each reservation increasing substantially from the year > before

The 17.6M projected nights makes no explicit assumption about the "length of each reservation." The 5 million nights published by AirBnB could have been 1 user booking a 5 million night stay (it wasn't) or 5 million users booking 1 night stays. It doesn't matter, the length of reservation is embedded in the statistics and not separately dealt with, so the author cannot be growing that assumption.

> the post is assuming maximum commission on each reservation

He does not use the maximum commission on each reservation, which we established would be 15%. Instead, he uses 13%.

> Payments collected on behalf of other parties (i.e., the payment fee) are > not treated as revenue under GAAP.

I'm not going to argue GAAP accounting, but from a _cash_ perspective, AirBnB is collecting 9 to 15% on each reservation. If a listing is for $100, the Guest pays somewhere between $106 and $112 per night (i.e., 6 to 12% markup) and the Host gets $97 ($100 less $3 or 3%). Therefore, AirBnB is generating revenue of $9 to $15 on every $100 in reservations.

<comment><USER5> Thanks hoodwink, appreciate the feedback. I posted hoping someone else would give it a sanity check. The numbers I was seeing were 100x what others have guessed.

> I really didn't have a clue in estimating the average room costs. I did a > sampling of the various geographic areas with high booking rates to come up > with $80.

> Also it's impossible to know the seasonal effects on the data. I'm wondering > for example what effect the Olympics had on the run up to 10M.</comment></comment></comment></comment></comment>