WebGL Fluid Simulation - <AUTHOR> https://paveldogreat.github.io/WebGL-Fluid-Simulation/ <comment><USER2> I tried this on my mobile phone, expecting it to not work properly, but everything was super-smooth. Impressive.

<comment><USER3> Yes, works beautifully on mobile! Even supports multi-touch. Awesome job.

<comment><USER4> Holy heck it does. Just tried five fingers and it worked flawlessly.

</comment></comment></comment><comment><USER5> Amazing project!

For what it's worth, the Github page references to the GPU Gems book for this effect: [http://developer.download.nvidia.com/books/HTML/gpugems/gpug...](http://developer.download.nvidia.com/books/HTML/gpugems/gpugems_ch38.html)

</comment><comment><USER6> Every so often you get an app that shows you just how fast modern hardware is when unencumbered by the usual endless layers of bloat and inefficiency.

<comment><USER7> To be fair this shader was published in GPU Gems 15 years ago (2004). Back in the days of the GeForce 6 and Windows XP. Though the fact that it now fits in your pocket is cool.

<comment><USER8> That is actually amazing. I mean the fact about 2004.

<comment><USER9> Yes, we were such illiterate savages back then.

</comment></comment></comment></comment><comment><USER10> Re: everyone impressed by how fluid it is with multitouch: The number of touch points doesn't affect the performance of a grid simulation. Using 10 fingers just sets high values at more places in the initial grid. The effort to solve each time step is the same after that. The computational effort scales with the resolution, not the boundary conditions/input.

<comment><USER11> I'm impressed it handles multitouch without scrolling or zooming the page. Many similar demos I've tried suffer from such issues.

<comment><USER10> That's true. The actual UI implementation of the multitouch is great.

</comment></comment></comment><comment><USER12> Default settings don't really do it justice IMHO. Try these:

Density diffusion: just a hair under 1(visually)

velocity diffusion: 0.99

pressure: 0.93

vorticity: 5

<comment><USER13> I also tried high Density Diffusion - loved the slower movement and that made me think - only if there was a way to export that to a something like a moving wallpaper that I could set to my Ubuntu desktop.

Also, just setting Density Diffusion to 1 and leaving makes the movement slow enough to be able to screenshot nice wallpapers.

<comment><USER14> Remember Microsoft's old "Active Desktop"?

It was like a webpage as a wall paper.

Maybe ahead of it's time as it crashed constantly...

<comment><USER13> I do. Coming from Win 3.1 and due to restrictions on internet connectivity in our office then, at first I had no idea how to use it and thought it was some advanced feature.

</comment></comment></comment></comment><comment><USER15> Impressive demo! WebGL is an awesome piece of tech that only now starts to be largely adopted. I mean, it gives you access to 100s of cores to compute, run, display stuff :).

Too bad Apple doesn't move forward with WebGL2 and Google splits the community in 2 with webgpu.

<comment><USER16> But WebGPU is more like Vulkan (in concepts) and WebGL is pretty much a 1-to-1 port of OpenGL.

It's not splitting the community. They needed a new modern API like what people behind Vulkan did.

<comment><USER15> 95% of the current games use OpenGL / DirectX 11 over Vulkan/ DirectX 12. Vulkan seems to be a nice to have with lots of potential in my opinion. I have yet to find a killer use case for Vulkan, on the web in particular.

With WebGL, in my current projects, the limiting factors are the network, javascript and RAM more than the opengl driver overhead...Maybe the reason behind it is to find common grounds with Apple and supports several investment around Stadia's core technologies?

<comment><USER17> You are missing NVN, GX2, libGNM and libGCN there, as OpenGL isn't a thing on consoles.

</comment></comment></comment></comment><comment><USER18> Here is the "main loop" for the simulation: [https://github.com/PavelDoGreat/WebGL-Fluid- Simulation/blob/...](https://github.com/PavelDoGreat/WebGL-Fluid- Simulation/blob/master/script.js#L1005-L1071)

I don't know enough about fluid dynamics to be the judge, but it seems like the engine is using genuine (2D) physics and it's not just "toy physics." Could someone who knows fluid mechanics comment on this?

<comment><USER19> Sure. It's a correct implementation of the projection method [1] for solving the 2D incompressible Navier-Stokes equations, so it is in fact using genuine physics. In terms of physical accuracy, there are some caveats - it's using the Jacobi method (chosen for its simplicity) to iteratively solve the diffusion and pressure Poisson equations, so the accuracy will be determined by how many iterations you're willing to do. That approach won't scale to larger systems. There are also some limitations from the choice of collocated (as opposed to staggered) grids and the approximations used for the boundary conditions. Nevertheless, for a small 2D simulation, you can get physically accurate results as long as you use enough Jacobi iterations and have a sufficiently fine grid.

[1] [https://en.wikipedia.org/wiki/Projection_method_(fluid_dynam...](https://en.wikipedia.org/wiki/Projection_method_\(fluid_dynamics\))

<comment><USER20> Also it uses backward differencing, it makes it stable at long timesteps. That is great to run fast for visualization, but it is horribly inaccurate (or possibly even plain wrong) if your system has large gradients in flow speed.

<comment><USER21> Yes, I've found that computer graphics focused fluid simulations frequently choose stability over physical accuracy. These choices also result in unphysically high numerical viscosity. (I didn't check what finite difference stencil or finite volume scheme the code uses, though I presume it's a lower order accurate one that probably has a fair amount of numerical viscosity.) In principle if you reduce the grid spacing and time step it will converge provided the software doesn't use any tricks like approximate square roots, etc.

The numerical methods for solving the PDEs that computer graphics folks use would surely be considered primitive by someone who develops engineering computational fluid dynamics softwares.

<comment><USER20> Don't get me wrong: Doing all the approximations to get a fast, visually appealing animation is perfect for what this demo aims to do.

Fluid simulations for science or engineering (think airflow around the next Boeing design or simulations of planet formation) are still very hard. And that is not because physicists are stupid, bad at coding or easily replaced with machine learning.

<comment><USER21> Sorry, I was unclear. I agree that the demo does what it intended to do. I was just listing a few additional reasons to believe it may not be physically accurate as-is. I know from previous discussions on HN that many readers are interested in this.

<comment><USER20> Totally good idea to do that. I just want other readers to be aware for what applications that is useful and for what applications other techniques are more appropriate.

</comment></comment></comment></comment></comment></comment></comment><comment><USER22> Reminds me of those cool visualisations that Winamp had, think they were called Milkdrop?

<comment><USER23> There is also the open source reimplementation of Milkdrop called projectM, which might be of interest to you.

[https://github.com/projectM-visualizer/projectm](https://github.com/projectM- visualizer/projectm)

</comment></comment><comment><USER24> I clicked this thinking "yet another fluid simulation" but this is _super_ cool. Played with every single parameter ;) Pausing, then drawing, then unpausing was a surprisingly pleasant effect.

</comment><comment><USER25> Really beautiful !

To have it full screen on mobile, you can use the "add to home screen" feature of your browser"

</comment><comment><USER26> The webpage links to an app which allows this to be your wallpaper and lock screen (on Android for sure). Absolutely awesome!

</comment><comment><USER27> This is my favorite app on my iPhone. Better than a fidget spinner.

<comment><USER28> Your comment inspired me to install the iphone app. My kids (2 and 4) are going to looooove this. Thanks!

</comment></comment><comment><USER29> Cranking all the values up to max makes for quite the show.

</comment><comment><USER30> If you guys like this, you'll like Verve (fluid dynamics painting tool):

[https://www.taron.de/verve/verve_download.html](https://www.taron.de/verve/verve_download.html)

</comment><comment><USER31> Such a nice demo! I'm amazed by how smooth it's running on my phone. Even if we already have seen similar shaders back in 2004, this is running on the web, available to everyone, with no installation.

During my 3rd year at uni I played with webgl1 to create a fake fluid simulation, my demo looks crap nowadays [http://jspdown.github.io/mod1/](http://jspdown.github.io/mod1/)

</comment><comment><USER32> This works with decent smoothness even on my 8 year old 35 dollar iphone 4s.

I met a fellow at Nasa Glen in the 90s that worked on fluid simulations using an sgi workstation. I don't remember how long the simulations took to process but had to be several minutes per frame. I do remember those workstations cost well over 30 grand at the time.

</comment><comment><USER33> Thought the tails/vortex look like curl noise. And after looking at the source, sure enough they are

</comment><comment><USER34> Colors are amazing. It's weird it triggered smell and feelings from 15-20 years old memories.

</comment><comment><USER35> WOW! Not only is it FAST, it does multi-touch too! Successfully did 4 fingers already, although saw it somewhat slow down but not much.

On a beefy system this could probably handle the full 10 point touch no problem!

I am doing this on a desktop (Arch + Gnome 3) with an Acer touch display.

Well done!

<comment><USER36> Woah, you're right. I just tried it on my Pixelbook screen (keep forgetting it's touch screen), and it handling as many fingers as I could give it (all 10) with no lag.

<comment><USER37> I'm guessing the number of inputs doesn't really influence simulation speed since the shader runs each frame for each pixel anyway. When touching the screen, some pixels are changed to hot/colored, but that doesn't really change the amount of computation needed to simulate the whole screen.

</comment></comment></comment><comment><USER38> This is so nice! The pause box makes the whole demo flex really well. Impressive work

</comment><comment><USER39> Although this is just a demo, it's really fun to use! Relaxing, even! Well done.

</comment><comment><USER40> This is gorgeous. It gives me a sense of joy and power when creating the vortices. The white glow seems to burn my eyes, even when I know my screen is not that bright. Feels like I'm a wizard.

Thanks to the creator.

</comment><comment><USER41> Super cool on iPad

It can track 10 fingers at once did not even know the iPad could do that.

<comment><USER42> Does it go to 11?

<comment><USER43> That's not a finger.

</comment></comment></comment><comment><USER44> Wow so cool. Any summary on how the algorithm works roughly?

<comment><USER45> The repo refers to this article: [http://developer.download.nvidia.com/books/HTML/gpugems/gpug...](http://developer.download.nvidia.com/books/HTML/gpugems/gpugems_ch38.html)

Looks like it's standard Navier-Stokes.

<comment><USER20> Not quite standard. The trick is to use backward differencing in time, to make it unconditionally stable even for longer time steps. Also the Poisson equation to get the pressure is only solved approximately by doing Jacobi iterations until the solution is "good enough". And of course it is limited to 2d and the incompressible limit.

</comment></comment></comment><comment><USER46> RIP Plasma Pong. Was bought by acclaim but was never sold..

</comment><comment><USER47> this keeps reappearing, but it never gets old

just a random recommendation: I love to connect this from a laptop to a TV screen, connect a wireless/long cable mouse, and play it with my cousins / little kids. it's a one time trick, but they always love it. (you can do the same with other programs / simulations, just enhancing the experience a little bit can do wonders)

</comment><comment><USER48> Super cool on Firefox on Moto X4! Five fingers!

</comment><comment><USER49> Whoa this is jaw dropping on mobile. Try typing in a density diffusion of .996 and setting velocity diffusion to 1

</comment><comment><USER50> Add a fullscreen mode and I think this will keep my toddler entertained on occasion.

</comment><comment><USER51> Nicely done. It's impressive how fluid and detailed the graphics are!

</comment><comment><USER52> Here's a React version of the above simulation: [https://github.com/transitive-bullshit/react-fluid- animation](https://github.com/transitive-bullshit/react-fluid-animation)

</comment><comment><USER53> Impressive! Works well even with 10 fingers on my touch screen.

</comment><comment><USER54> Just makes you appreciate how impressive modern hardware is.

</comment><comment><USER55> Wow, this is so... fluid! Even on a mobile device.

</comment><comment><USER56> Does not seem to work on Firefox 66.0.5

<comment><USER57> Works just fine on 66.0.5 for me (On MacOS).

<comment><USER58> Firefox 66.0.5 on Ubuntu checking in.

</comment></comment></comment><comment><USER59> Screenshot capture fails, the download fails with network error. No errors are reported in console or the network tab.

</comment><comment><USER60> My cat loves this on the iPad

</comment><comment><USER14> I could do this all day....

</comment><comment><USER61> this is gorgeous!!

</comment><comment><USER62> I AM A WIZARD

</comment><comment><USER63> The effects are very slow on chrome v74, but super smooth in FF v66. I suppose that's Electrolysis[1] in action.

[1] [https://wiki.mozilla.org/Electrolysis#Overview](https://wiki.mozilla.org/Electrolysis#Overview)

<comment><USER64> Check chrome://gpu

<comment><USER63> [https://pastebin.com/LDMjLWgn](https://pastebin.com/LDMjLWgn)

I suspect the nouveau video driver is the culprit.

I'm currently using Ubuntu 18.04</comment></comment></comment>


Ex-Googler's startup comes out of stealth with simple, clever robot design - <AUTHOR> https://spectrum.ieee.org/automaton/robotics/home-robots/hello-robots-stretch-mobile-manipulator <comment><USER4> Things it can't do:

\- go up stairs

\- get up after a fall / reset itself

\- pick up heavy objects

\- precise motion (so no cooking)

\- interact with buttons or touch screens (so laundry might be hard)

The one use case I think it might be worth it is if the robot can take a room full of toys and return everything back to where it belongs. Kind of like a one click, reset this room. If it can help me keep organized and clean around the house that would be a big win. Also, if it can help me detect which clothes are still wearable and which I should probably wash, that'd be nice.

I'd gladly pay 5k for a robot that can auto-organize my stuff around the house, even if it involves a lot of customization and setup. Imagine leaving your groceries next to the fridge and coming back to a perfectly organized fridge. Or letting your kids play in the play room and then the robot comes in and puts all the toys back. Or if you just tend to leave stuff out (throw your clothes on the floor or forget to return stuff), the robot can put it back.

I think that's a legit use case.

<comment><USER5> > _I 'd gladly pay 5k for a robot that can auto-organize my stuff around the > house_

The main equation for general-use household robots is: can it beat human fares?

A good weekly cleaner (4 hours) is about €22/h in Paris, or €4.5k/year.

Let's say your robot lives 4 years, similar to your computer (which seems fair, since it is one, and an abused one at that). Since you amortize its price over 4 years, its initial cost must be below €18.3k ($21k) with human- quality-parity.

Personally, though, I would bet on dedicated, single-purpose robots, working together through wireless communication. Simpler to build, less costly, easier to replace. One small wheeled quadcopter for cleaning surfaces, one wheeled laundry box to carry it to the washing machine, one arm attached to the washing machine to put it in, etc.

<comment><USER6> a human cleaner isn't really a perfect substitute for a robot. people might feel uncomfortable with having a human worker in their house for a variety of reasons. most people I know actually clean their whole house before the cleaning service shows up. you don't have to feel guilt/embarrassment at the state of your house when the robot starts working. I could imagine a lot of people might be willing to pay a premium for this, even if the robot doesn't do as good of a job.

<comment><USER7> There's something darkly funny about people so embarrassed to have a cleaning person in their house, that they create a solution that would put most cleaning people out of a job.

The knowledge workers automate jobs away, leading pundits to say the future for low-skilled workers is to provide boutique services for the upper class. The end being that the upper class is too ashamed to actually consume those services if it means looking at a person...well, that's sort of a delicious irony, isn't it?

<comment><USER8> I have never hired a cleaner, but I imagine there are also people who are uncomfortable having strangers in their house and handling their things.

I have also heard about people getting cleaners who initially do a good job, but whose work quality degrades over time. You wouldn't have that problem with a robot.

<comment><USER9> Until it gets a million software updates to add "features" that are really just ploys to slow the device down and encourage you to upgrade ;)

</comment></comment></comment></comment></comment></comment><comment><USER10> Kids' chores 2000: Take out the trash, 2 minutes.

Kid's chores 2020: Up until 3AM programming the robot to take out the trash. Purchased the robot two weeks ago. Kid only moves to go to sleep. Trash is building up. No other chores are getting done. Chores dashboard is flashing red. Take out trash sprint way overdue.

<comment><USER11> Calvin and Hobbes already did this plotline [https://www.gocomics.com/calvinandhobbes/2014/09/01](https://www.gocomics.com/calvinandhobbes/2014/09/01)

<comment><USER12> "It's only work if someone makes you do it"

how true

</comment></comment></comment><comment><USER13> In 2014, I was at Google and went to an open house event at the Google robotics lab in SF. The people I met there were nice. I almost applied for a job there. Then I looked up the person who would have been my boss. He was scowling in his Google profile photo. His LinkedIn showed him as founder of a robotics company, with no mention of Google. He obviously wanted to be the CEO of a robotics company, not a director in Google.

Google acquired many robotics companies in 2013. I believe most of the acquired companies' leaders had contracts requiring them to stay at Google for 4 years.

Did Google delay the progress of robotic technology by 4 years?

The VC model obviously helps enable human progress in many situations. But surely not all situations. How can we know when the VC model will be a net loss for humanity?

I'm glad to see those folks moving on and following their dreams.

<comment><USER14> Given the net number of massive companies that emerged from VCs, this is obviously not true.

<comment><USER15> It doesn't tell us anything one way or the other. That's survivorship bias talking.

<comment><USER14> Your sample is wrong. We are comparing the number of successful new companies that came out of VC vs the number of successful new companies that came without VC.

...and it's easily obvious that almost _all_ of the new large tech companies emerged from VC.

<comment><USER15> No, that's what you are doing. What I'm doing is comparing the number of successful companies that came out _given that the VC system exists_ versus a situation where it doesn't. We don't know how many potentially successful companies haven't been started, or got strangled in the crib, because of the dynamics of the VC ecosystem and the fact that it exists.

Also it's an error of remarkable proportions to assume that "massive company" is synonymous with "net positive to humanity", _particularly_ in tech.

</comment></comment></comment></comment></comment><comment><USER16> Nice. Certainly more affordable than the huge Willow Garage machine, although that could fold laundry. This thing will probably be showing up in robot research labs. If they sold a reasonable number it could be much cheaper.

The arm is not very rigid. Notice there's a barcode target on the end effector base (the "wrist") where the camera can see it. So the system can compensate for some bend. That's in some ways better than building a super-rigid structure.

I'm surprised there isn't a camera or two out at the end of the arm, for fine positioning. Cell phone camera parts are so cheap now that's a no-brainer.

</comment><comment><USER17> > ex googler

Does this mean we get lots of hype and an inferior product that is eventually phased out an replaced by an acquisition built by non-google engineers?

<comment><USER14> I'm going to just start putting that on all my PR. Ex-Googler. No one is going to check, and if it biases the opinions of idiots... so be it...

<comment><USER18> The sooner you're exposed as a fraud the better. So please definitely use it :)

<comment><USER14> The reality is that unless you're well known - no one cares if you lie about this stuff.

<comment><USER18> Please go ahead and do it.

</comment></comment></comment></comment></comment><comment><USER19> That's funny. Just yesterday I wrote a blog post that mentioned telerobotics [1], as I've become interested in how the global economy has changed since 1990.

The book I was reading that inspired it (which I thoroughly recommend) [2] talked about how telerobotics was going to help break down the last of three constraints on globalisation: moving people.

The other two are: cost of movement of goods (1st modern industrial revolution); and the cost of moving knowledge (the 2nd modern revolution, since 1990).

One of the things argued is that cleaners and dog walkers (for example) can't be moved, so a paradox of high skills economies is that certain low-skill jobs become more valuable.

$20K is getting frighteningly close to start making it more economical to have someone operate such a cleaning machine remotely from a low cost area than hiring a local cleaner. Skilled operators could even (with the help of AI?) operate dozens of these at once. Or they could do the 'easy' stuff, and get a 'proper' local cleaner in once in a while to do the tricky bits or a deep clean.

Interesting times.

[1] - [https://zwischenzugs.com/2020/07/13/why-do-we-have-dev- rels-...](https://zwischenzugs.com/2020/07/13/why-do-we-have-dev-rels-now/)

[2] - [https://www.amazon.com/Great-Convergence-Information- Technol...](https://www.amazon.com/Great-Convergence-Information-Technology- Globalization/dp/0674237846)

<comment><USER20> That's an interesting train of thought, but I hope it is not the future. The world population is still growing. Labour is still the biggest wealth distribution system for most people. To eliminate "low-skill" jobs seems like an inhumane way forward. It will likely increase inequality.

Also to take your example: walking a dog can also be considered a high-skill job. Sure you don't need a degree, but you need empathy and kindness. Pretty hard to teach to some people.

</comment></comment><comment><USER21> The idea of it being controlled by a remote person makes me feel like a new breed of gig-jobs could be around the corner.

Buy a robot, and pay someone remotely to do your housekeeping for you. The housekeeper could even operate it from their smartphones.

<comment><USER22> Why remote? There's plenty of people nearby you can hire that can do the job better, faster, and cheaper.

The only downside is that you've got a real person in your house, but honestly if that's a hangup then you need to suck it up and just do the work yourself.

<comment><USER23> (1) no "foreigner in my home" cleanliness issue - especially pertinent during these dimes

(2) no "will the cleaner steal my golden watch / company's data" issue - <USER2> can always just replay the video and see exactly what the operator was doing / looking at

(3) ability to hire different people remotely - not just cleaners, but maybe repairmen, doctors, chefs, ...

</comment></comment></comment><comment><USER24> I'm always surprised how much these things cost. A 3 axis CNC is basically a 3 degree-of-freedom robot, yet only costs a few hundred dollars. I think we'll see mobile autonomous robots come into people's homes only after they:

\- fall to low thousands price range

\- do something useful (ie. not just a "social robot")

<comment><USER25> I think you forgot a zero there. A 3 axis CNC mill usually costs a few thousands of dollars. There are some crappy CNC engravers and dirt cheap 3D printers but the rigidity requirements are so low that they are a completely different class of machine.

<comment><USER24> There is a pretty big range of prices. The cheap Chinese ones aren't necessarily well built but they work fine for hobbyist stuff.

Motors, motor controllers + motion system are cheap enough for affordable home robots I think. The problem is automating actual tasks with the limitations of the motor controls.

<comment><USER26> Unfortunately the controls problem gets much harder in a non-rigid system. Now you have to solve autonomy AND overcome poor sensing and manipulation.

</comment></comment></comment></comment><comment><USER27> Alternative title: "Startup offers one armed, remote controlled 20.000$ robot on wheels with limited autonomous capabilities"

What's the use case besides novelty purposes? Who is supposed to buy this? Solely quadriplegic people come to mind but even that is a stretch and it's far too expensive. This is lightyears away from being a useful consumer object like a vacuum robot. If this is peak robotics, it is very disappointing.

<comment><USER22> Research; as the article states, it's a research platform. It's up to hackers and stuff to come up with ways to use this platform.

<comment><USER28> Hackers with a spare 20K?

<comment><USER29> Research labs

</comment></comment></comment></comment><comment><USER30> From a customer and person outside the SV Chocolate Factory bubble perspective this is a $18K Roomba with coat stand.

<comment><USER31> Silicon Valley never ceases to amaze me with how willing they are to overpay for underperformance with the promise of future overachievement

<comment><USER32> Silicon Valley is like a casino lot of bets going on but in the end the house always wins.

</comment></comment></comment><comment><USER33> The potential here is amazing. It's very early days, but this is the first Robot I've seen that makes me think home assistant robotics is technically and financially feasible. It does not need to be consumer priced from day one as there are many high value scenarios that could benefit from this robot. For example, home care in Europe costs governments millions every year. Even remotely controlled by a carer would be an application for today.

<comment><USER34> I would love to be as positive as you. Let's say minimum wage is $15 an hour, what task do you think this robot could do, and how many hours of labour will it save? I don't want to be overly negative, but to honest the way it comes across to me is they've taken a roomba, glued a stick on top of it, zip tied a hoover onto it, and invented a slow, bad roomba.

</comment></comment><comment><USER35> In the demo video, for every basic task it needs some setup by a human (see how they fixed stuff on the stretchable arm for every action other than picking-up something) and all the interesting tasks were teleoperated.

I don't care about teleoperation, for a home robot I want automation.

<comment><USER36> That reminds me of a book I read as a kid: "My Trip to Alpha I" by Alfred Slote [0].

[0] [https://www.goodreads.com/book/show/3201020-my-trip-to- alpha...](https://www.goodreads.com/book/show/3201020-my-trip-to-alpha-i)

</comment></comment><comment><USER37> Mobile base with a long stick on top, camera on top of the stick and arm moving up and down the the stick: I'd say that's a proven design featured in many custom-built robots for RoboCup@Home.

This has some potential.

<comment><USER22> I just don't know why it's costing 20K. Maybe because it's not mass-produced?

</comment></comment><comment> tuna-piano It's so obvious what is needed to help these take off: an app/skill store with an easy development environment. Would assume the order goes something like this:

$20k robot -> robot app/skill store -> Killer apps??? -> More volume ->... $3k robot -> More apps/skills -> $1k robot -> Everyone has one.

</comment><comment><USER38> this is very cool. could anyone help break down the costs?

specifically:

1\. what are the most expensive parts, and how fast is technology advancing (or costs declining) on those parts?

2\. what scale is necessary for a comparable robot to retail for < $1000?

<comment><USER39> 1) Most expensive individual third-party components would be all the servos together, then the computer, then the realsense, then the lidar. All the custom body panels and custom cut carbon fiber extrusions are expensive now, cheap when scaled.

2) 5,000 - 50,000? Right now it's about twice as expensive per kilo as a Lamborghini Aventador, and they only made ~4,000 of those. It needs to be 18x cheaper to hit your price target, and that wouldn't be impossible at scale. A big chunk of the price tag is generous margin (because they don't know how many they'll sell) and paying for the software, which amortizes well. Those costs go away at scale, but then you need to spin up tech support and a repair department. I do tech support for educational robots, and I can tell you it's not... simple, or profitable.

Getting to that number would be hard. The design of the robot is _wonderfully_ simple, (great! delightful!) but it's too easy to clone: the only complicated bit is the telescoping arm. Everything else is open source or commodity parts off the shelf. If they actually do sell a thousand of these, the Chinese will rush in and eat their margin. I hope either they have patents and some aggressive lawyers, or friends high up in the Biden administration, because if the design is successful, their company won't survive international competition.

<comment><USER40> The telescoping arm is cute, and provides benefits for reaching into constrained spaces like a washing machine, but in the first clones it would likely be replaced with the standard "cylindrical" (e.g. industrial robot style) arm. Hard to imagine that they could have gotten a patent on "robot arm on Segway". The elevator part though?

<comment><USER39> A conventional arm? Oh no thank you. Heavier, need a motor out on the elbow joint with another expensive low-backlash gearbox, mast has to be heavier to support the off-axis torque loads, grasp trajectories have another DOF or two. Skip that, please. And it's not like conventional arms are even _cheap!_ If you could buy a decent 1.5 kilo payload arm for less than $5k, you'd have a whole different argument.

From the way the telescoping arm moves, I'd bet dollars to doughnuts it's driven by a flex-tape linear actuator. Pretty cheap, lets you put the heavy motor right next to the mast, no precision bearings, backlash not so much a problem.

The whole package really is a great design, I'm a big fan. You can tell Edsinger has been using robots out in the real world, with regular people beating them up.

</comment></comment></comment></comment><comment><USER41> Contrarian point of view -- (edit) this clever device overall takes too much capital and solves no real problem, meanwhile pressing and urgent problems needing tech, remain unaddressed, year after year.

For centuries, real, physical actions in home life were improved with (mainly mechanical) devices subject to patent. The industrial revolution provides vast flows of consumer goods. Finance prospered (mainly) with loans, interest, and selling inventions like these, on large markets.

Fast forward 100+ years. Daily life is unimaginably easy, due to mass market goods for cheap, standardized living and generally, massive energy use. Markets constantly create products designed to be profitable given some game rules. Yet, there are diminishing returns. Vast, serious, ok yes _urgent_ challenges face individuals and society, right now, and have been known for several decades.

An analogy might be the stunning success of mathematics in physics over the last 100+ years, sends multiple other soft sciences scouring math for certain curves or constants, because it worked for physics. Repeatedly, social science for example, is subject to physics-like curves and constants, searching for computable understanding, which is probably not appropriate to the endeavor.

The market is scouring product space, using formulas from long ago, to make the "killer" product. They say it here in the comments. This is to make money for people who are already very wealthy, using formulas that include massive diminishing returns (huge capital, you bet), and basically solve no real problem. Labor is over-abundant in modern times. People are living in isolation in Western Cities, and this is an isolation device. A very modest arrangement with a living person who needs work to earn money in the city, would solve the "problem" here, and requires no capital.

I suggest these talented, funded inventors look more deeply at the real ecosystem we are faced with overall, and get off of the gerbil wheel of get- rich personal consumption devices, because overall, societal survival actually does depend on tech right now.

<comment><USER42> > get-rich personal consumption devices

I guess you don't have any disabled friends/family.

<comment><USER41> oddly, you are completely incorrect

</comment></comment></comment><comment><USER43> For comparison, here's the PR1 from 12 years ago:

[https://www.youtube.com/watch?v=oyHWkQcin7I](https://www.youtube.com/watch?v=oyHWkQcin7I)

</comment><comment><USER44> I'm looking forward to the day a small home robot can do the dishes, in the sink – replacing a dishwasher machine. This looks like a small step in that direction.

<comment><USER45> Wondering what the benefit of a dishwashing robot is? Better off just wishing for a more convenient / compact dishwasher, I think.

<comment><USER46> It takes me an inordinate amount of time to place objects into the dishwasher so that it doesn't have 50% wasted space. Also if you eat East Asian dishes you will have tons of sticky bits of rice, and a dishwasher never seems to be able to scrub them. (Maybe it will if I run it extra hot, but then it will damage plastic lids. You can't win.)

</comment></comment></comment><comment><USER47> I see this being used by low cost remote operators to cleanup your room or do your laundry. Autonomy is still a gimmick, but imagine if you can pay $50/month so that a reliable remote operator (entire armies of call centres will turn into remote robot operators) swipes every surface with a cloth?

</comment><comment><USER48> A lot of excellent discussion here. A few years back at CES, I saw the concept of an appliance that will automatically fold your laundry. It was amazing to see (yet IMO a hoax). I maintain a robust and cheap solution to make the bed or fold laundry could be a game changer.

</comment><comment><USER49> The main thing I see missing in these comments is the approach from the other end. There will be a tipping point where appliance makers design small features to make their products "robot friendly." Like making openings larger, buttons larger and otherwise easier for cheaper robots to interact with. And it will create a feedback loop where robots get more popular because they can do more in a robot enabled home, and because they are more popular they get better, and because they are better they get more popular.

Let's be honest, the roomba sucks, so It's not really a counter argument.

Once there is a robot that is useful and also seen as a status symbol, that's when the feedback loop will begin.

</comment><comment><USER50> "As of right now, Stretch is very much a research platform."

That was buried way too low in the article for most HN commenters to bother getting to. Maybe this fact will help refocus the conversation from what this thing can't do to what it might be able to with some more work. Personally, I think it looks innovative. Adding a relatively inexpensive telescoping arm and some LiDAR to a Roomba could be another evolutionary step forward in home robotics.

I can _easily_ imagine wiring this thing up to Alexa and asking it to go get me a drink from the fridge. That alone would be worth a few hundred bucks when it becomes a commercial product.

<comment><USER51> That's the journalist's fault. The manufacturer's site is clear about it. [https://hello-robot.com/product](https://hello-robot.com/product):

        Stretch™ Research Edition
        A new kind of robot.
        […]
        A Robot for Researchers by Researchers

I couldn't find specs on typical battery life (would likely vary a lot, but still, any indicator would help) but it has an 18Ah battery (ballpark "3 laptops"), an Intel i5-8259U, 16GB of RAM and a 480GB SSD.

</comment></comment><comment><USER52> Seems very slow, guess robotics really is hard.

<comment><USER53> We know how to make fast robots, we know how to make safe robots, and we know how to make useful robots. But we do not know how to make fast, safe, useful robots. A faster robot would need to be heavier to do the same work.

Any robot that can move as fast as a human and perform similar work to a human will need to be close to as strong/heavy as a human. And humans can kill each other with their bare hands; we just know not to. A Kuka LBR iiwa can only lift 7-14kg, but could easily accidentally kill/maim someone with common payloads of that mass.

Obviously there's also some slowness w.r.t. the actual control here (i.e. safety pauses, planning latency, etc.), but it's a tall order to build any kind of home robot - especially one that has such a large workspace - that is intelligent enough to be both fast and safe.

<comment><USER52> That's a very good point, which I guess can't really be solved since we'd always have to trust the software in one way or another.

</comment></comment></comment><comment><USER54> Already now this looks like a very useful tool for a person who is bound to a wheelchair. It can easily reach things at different heights, including floor level, which is hard from a wheelchair. Its base is smaller than a wheelchair, so it can get into narrower spaces. Such person probably has an open, level, and uncluttered floor plan already, which works well for the robot. Accessories, such as the vacuum cleaner, can be installed by the operator (after the robot fetches them). Autonomy is great when it works, but even slow teleoperation is better than having to have a helper around 24/7.

</comment><comment><USER55> > he hopes to see the robot deployed in home environments,

It will need bigger wheels or legs then because it would be stuck in one room in my house because of the thresholds at each doorway and the rugs and carpets.

And my house has three stories so I would need three of them because it can't climb stairs.

It's getting tiresome to read crap like this because while it _might_ work in a dwelling purpose built for it it is guaranteed useless in most dwellings occupied by real people right now.

<comment><USER56> With three stories you can afford three robots. Imagine being the operator waiting for these things to go up and down stairs, that sucks.

</comment></comment><comment><USER57> I admire the hard work that surely went into this, but I have to say: as a former robotics hobbyist, I'm extremely unimpressed with the weight, cost, and limited capabilities of this thing. And that impression is based on the technology we had over a decade ago. With access to a few machine tools and a 3d printer, I'd bet an equally capable prototype would cost no more than a few hundred dollars. No wonder almost no one has a robot in their home.

<comment><USER58> Ya but did you know the founder used to work at google?

</comment></comment><comment><USER59> I think this should be looked at similarly to e-readers that came before Kindle or smartphones from before the iPhone. It's not 'there' yet, but it shows the directions things can go, and can help pave the way toward something that deserves mass adoption. Bringing down the price is a big step, so more people can try it out and maybe even discover a niche where it's already 'good enough' for some task.

</comment><comment><USER60> Obviously the design is not perfect, but I think this is a step in the right direction, as in, a robot does not have to be a bipedal humanoid to be useful.

</comment><comment><USER61> This is quite literally a USD 18,000 "reacher" [1].

I remember a reacher being a pretty successful present last time I played "white elephant gift exchange" :-).

1: [https://www.amazon.com/Reacher-Foldable-Lightweight- Reaching...](https://www.amazon.com/Reacher-Foldable-Lightweight-Reaching- Extension/dp/B078RMCFWQ)

<comment><USER62> > "I had this idea that there are these assistive grabbers that people with > disabilities use to grasp objects in the real world," he told us. Kemp went > on Amazon's website and looked at the top 10 grabbers and the reviews from > thousands of users. He then bought a bunch of different ones and started > testing them. "This one [Stretch's gripper], I almost didn't order it, it > was such a weird looking thing," he says. "But it had great reviews on > Amazon, and oh my gosh, it just blew away the other grabbers. And I was > like, that's it. It just works."

There's a few "grabbers"/"reachers" that have a gripper that looks pretty similar to the Stretch's; I'm not sure if there's an "original" that the others are clones of: [https://amzn.com/B07RR6N9C7](https://amzn.com/B07RR6N9C7) [https://amzn.com/B0812B4TF1](https://amzn.com/B0812B4TF1) [https://amzn.com/B01MAW25UW](https://amzn.com/B01MAW25UW)

</comment></comment><comment><USER63> For anyone in the space, how substantial is the "research robot" market? What's realistic, hundreds of units, thousands?

</comment><comment><USER64> > The arm was "one of the most significant engineering challenges on the robot

There's not much to the robot besides the arm, so, um, yeah?

</comment><comment><USER65> I'm not impressed. It is not a "grand engineering breakthrough" by any stretch of imagination.

</comment><comment><USER66> [http://archive.is/h0yap](http://archive.is/h0yap)

</comment><comment><USER67> I can totally imagine this being Amazon's next big play. They already have a decent in-house robotics team working on warehouse automation. Some of that knowledge could be spun-off into a consumer robotics unit. Alphabet will be left catching up again like with AWS and Echo.

</comment><comment><USER68> Looking like a 3D printer with camera gimbal attached to the carriage is bolted atop a robot vacuum...

</comment><comment><USER69> Here's a more practical example of this kind of design and the robots don't cost much more.

[https://scoutsomerville.com/wp- content/uploads/MG_4809-1.jpg](https://scoutsomerville.com/wp- content/uploads/MG_4809-1.jpg)

</comment><comment><USER70> I prefer these...

[https://boingboing.net/2016/06/08/the-amazing-shitty- robots-...](https://boingboing.net/2016/06/08/the-amazing-shitty-robots- of.html)

</comment><comment><USER71> Robots have a big problem - price tag. Research robot for $18k, Spot for $75k, single robot arm moving stuff from A to B - $50k+. How many organizations can afford that? No wonder, that robot adoption is extremely slow.

<comment><USER72> If something like this succeeds to the point of mass production, I could easily see the retail price been cut by 75% or more. That might be a big "if", though.

I imagine a bit of the current price tag is "we want serious purchasers who will be partners in the development of this device"; they don't want to build them for people who will just dick around with it for a bit and then relegate it to the corner of the room.

<comment><USER73> Yeah I don't think the world needs household robots that are disposable. I'd expect them to be a similar investment to a high end car in the interest of a lower total cost of ownership over long timeframes. It would ultimately be very expensive to make wave upon wave of "cheap" high tech landfill fodder.

What I'd like to see is standardized interchangeable parts and configurable software so we can spec robots to their tasks and benefit from reuse of parts and code as much as possible.

</comment></comment></comment><comment><USER74> Are any tele-robots used in agriculture? I could imagine using AI to get the robot hands within a few inches of each piece of produce or a desired task and then one operator could quickly swap between many robots.

<comment><USER75> I think some tractors have tele-operation capability, but the farmer typically sits within them to monitor operations

</comment></comment><comment><USER76> Something the Stretch bot gets right is that it doesn't trigger uncanny valley revulsion like the torso-shaped PR2 does with its Terminator eyes. They managed to make this bot feel like an appliance or a mobile coat hanger - almost like an endearing doofus. I think this will be key to mass adoption.

On the other hand, those Boston Dynamics robo-dogs with their snakelike extensions reminds me far too much of the Fido enemy (a.k.a. Parasite) from Quake 2: [http://vignette1.wikia.nocookie.net/quake/images/d/d2/Parasi...](http://vignette1.wikia.nocookie.net/quake/images/d/d2/Parasite.jpg/revision/latest/scale- to-width-down/185?cb=20130427135231)

</comment><comment><USER77> The base looks like the clearance is too low and wheels too small, but otherwise a nice idea. I'd imagine you could replace the base with a quadruped for better mobility.

<comment><USER78> Cross-breed Boston Dynamics' Spot?

</comment></comment><comment><USER79> But...is it cat compatible?

[0] [https://www.youtube.com/watch?v=3_SfDru0m_4](https://www.youtube.com/watch?v=3_SfDru0m_4)

</comment><comment><USER80> People are complaining about what this can't do, but for the disabled, the simple things it can do is going to be monumental. I see this as an amazing tool for the disabled, not a "beer me bot" for the lazy.

EDIT: And I should add, I hope they market this to that severely underserved market. If they only market it as a product for the rich to do simple tasks, it will suffer Segway's fate. If they create a market for it in healthcare and partner with those already in that space, this could be something big. It would pay for itself for people who need 24/7 care, if it were reliable enough.

<comment><USER14> For me the ability to do laundry alone is worth $$$. That is 90% of the reason I have maid service (family of 5).

</comment></comment><comment><USER81> Seems like progress in personal robotics has been incremental at best ever since Paulie had that robot deliver him a drink way back in Rocky IV (1985).

</comment><comment><USER82> The link to hello robot github [https://github.com/hello- robot](https://github.com/hello-robot)

</comment><comment><USER83> Re-enforcement learning would be fun on this one.

</comment><comment><USER84> imagine thousands of years ago, if you were very rich, you would stay away from rivers because of the risk of flooding - but you still needed a source of water - so you hire people to carry water from the streams to your home.

how would you automate that? by building robots to carry the water containers? what is the optimal solution may not be the most obvious.

</comment><comment><USER85> They dropped the ball on the demo. If they really wanted to blow me away they'd have demonstrated the robot opening the fridge and bringing me a beer.

A bit more seriously, this is a research platform. Maybe in 5-10 years it'll prove to be the seed of some interesting tech, but right now it's just a lab experiment. If you buy this and expect it to do basic housework for you, you are destined to be disappointed.

</comment><comment><USER86> I wonder why ex-faang company needs to be mentioned as a description of the founder.

<comment><USER87> Why not?

Most normal people would take that as a sign that the founder has already had a sucessful career in tech, because "FAANG" don't hire mediocre workers. The journalists knowing this trend, use this information to communicate this to people, speaking in their language. (Also this language makes some sense as well.) I don't see a problem.

<comment><USER88> > because "FAANG" don't hire mediocre workers

Their propaganda is working well I see. Having a Stanford degree and being able to answer CS questions (two things FAANG companies love) does not guarantee you'll be a good worker.

</comment></comment></comment><comment><USER89> $18k

<comment><USER90> At $1.8k it would be amazing, at $18k it's a big stretch. I would buy it at $1.8k.

<comment><USER91> $1.8k buys you a mid-range bicycle. $2.5k buys you a high end laptop. Both of those are made in millions. This is roughly a combo of the two.

So I'd guess that with sufficient volume this could get down to the $5k mark.

<comment><USER92> and a iRobot Create 2 is $0.2k

</comment></comment></comment></comment><comment><USER93> Design is either lacking or ugly (industrial) not suited for most homes.

</comment><comment><USER94> Someone should repost as soon as a 200$ Xiaomi clone is available.

</comment><comment><USER95> My guess is that this will need two arms to do many things!

</comment><comment><USER96> Great, now I can home from work!

</comment><comment><USER97> Utterly fails the site test, just like that gyroscopic scooter. And when it comes to a robot, the sight test matters.

</comment><comment><USER98> Damn that's a price tag

</comment><comment><USER99> Looks nice, but $20k??

</comment><comment><USER100> Shoes on the table!

</comment><comment><USER101> Feels like it would overbalance given how lightweight and tall it is - <USER3> time it tried to pick anything up that was even slightly heavy it would just fall over.

<comment><USER102> Detecting how heavy an object is would be possible - also those grippers will simply not grasp something too heavy. Your big problem will be simply in not detecting some object that coat-hangers it.

Let's not pretend a consumer model is even remotely ready though, these scenarios are highly contrived. The goal at the current time is research, and at that price point there are a few options available.

</comment></comment><comment><USER103> I'd like to buy one and try to have it build a robot like itself. Would I be able to sell them? Maybe now but not the version in 2040.

</comment><comment><USER104> Could this be scaled down to the desktop to be used for pick and place projects? If so, might be a revolutionary upgrade for the makers ..

</comment><comment><USER105> Out of curiosity, what kind of robot can you get out of Asia for $20,000?</comment>


Musk says Tesla won't show a profit until 2020 - <AUTHOR> http://www.businessweek.com/news/2015-01-13/musk-says-tesla-s-china-sales-fell-no-profit-until-2020

<comment><USER2> Meanwhile, investors will continue to push the stock higher.

<comment><USER3> You sure? It's dropped more than 5% today.</comment></comment>


Did Steve Jobs Coin the Term "Apps" to Make People to Think of APPle? - <AUTHOR> http://www.keenerliving.com/did-steve-jobs-coin-the-term-apps-to-make-people-to-think-of-apple I thought you might get a chuckle out of this. I'm not the best comedian ... maybe some of you can make it funnier with a spin-ft. <comment><USER2> I appreciate that this is a joke, however it disheartens me when I hear people associate the word "app" with only mobile software or particular software packages, especially as I've been using the word "app" as a shortened version of "application" to refer to software since Windows 95.

Oh and by the way, Apple attempted to claim that "app" stood for "apple" last year when they were trying to block companies from saying "App Store". Of course, Steve Jobs had said "Android App Store" publicly in the past so nobody really believed them.

<comment><USER3> Well, also, NeXTStep's application bundle was .app <http://en.wikipedia.org/wiki/Application_bundle>

So, Apple's usage of it probably came from NeXTStep (still Steve Jobs) which became OS X, which was also basis for iOS.

<comment><AUTHOR> sehr interessant!

</comment></comment></comment><comment><AUTHOR> Intended to give you a chuckle. I'm not the best comedian, so if someone wants to one-up it with a spin-off, fine with me.

</comment><comment><USER4> My calculator had an "APPS" button way before any iDevice hit the market, so no.</comment>


Things I wish I knew about MongoDB a year ago - <AUTHOR> http://snmaynard.com/2012/10/17/things-i-wish-i-knew-about-mongodb-a-year-ago/ <comment><USER2> Genuine question:

In what use cases does mongo kick mysql's ass?

I've used it a couple of times in hobby projects and enjoyed not maintaining a schema. I read so many of these 'gotcha' style articles and for example one commenter here wants to have a manual "recently dirty" flag to combat the master / slave lag mentioned in the article. I know it's faster (tm) but once you have to take in to account all this low level stuff you have to worry about yourself wouldn't it just be better to rent/buy another rack of mysql servers and not worry about it?

Look forward to learning something...

<comment><USER3> MongoDB kicks ass in the following situations (real projects I did as a freelancer):

\- dealing with semi-structured input (forms with some variability) and storing as a document, all while being able to query across the data

\- used as a store to provide very flexible ETL jobs (with ability to upsert, filter/query, geonear etc)

For those situations, I would definitely use MongoDB again. As a RDBMS replacement, I wouldn't use it today.

<comment><USER4> To slightly rephrase the OP's question:

      In what use cases does mongo kick postgres's ass?

To the two points you mentioned:

\- semi-structured input can be saved as hstore type or as json type;

\- and for flexible jobs, you can use pretty much any popular language - PL/R, PL/Python, even PL/C if performance is really critical.

<comment><USER3> I would have replied something similar if that was the question :-) (I use PG a lot these days).

Agreed on the first point (but I'm not sure you get exactly the same type of flexibility in all my use cases - I'll have to make a closer comparison).

For the second point, well not having to handle the schema for ETL jobs is sometimes fairly useful and removes a lot of cruft, that was part of my point (those ETL are code-based, only relying on MongoDB as a flexible store).

<comment><USER5> You can't query JSON easily and hstore is only one level deep. So, no, its not as flexible.

</comment></comment></comment></comment></comment><comment><USER6> I'm so glad this wasn't another case of someone just ranting about using mongo for the wrong purpose and being mad about it a year later.

<comment><USER7> I also appreciate how he pointed out positive things that he just wasn't aware of initially.

</comment></comment><comment><USER8> The count({condition}) one is a worry. I'm guessing it is slow in the case where it has to page the index in in order to count it. I wonder if it is still a problem where the index is used a lot anyway. A fix in MongoDB would seem a lot better solution than having everyone implement their own hacky count-caching solution.

EDIT: Actually, looking at the bug reports, sounds like maybe lock contention on the index?

The master/slave replication problem seems bad but I think it can be worked around (for my particular project) with a flag on the user session ... if they've performed a write in the last 30 seconds, set slaveOkay = false. Users who are just browsing may experience a slight delay in seeing new documents but users who are editing stuff will see their edits immediately.

</comment><comment><USER9> The inconsistent reads in replica sets is something we've come across with MySQL read slaves as well. I think it's a gotcha of that whole model of replication, rather than a MongoDB-specific issue.

<comment><USER10> I'm not aware of any database that solves this problem. Is there one? As far as I know, mysql reads must be distributed to the slaves at the application level, which has no knowledge of master/slave inconsistency. I suppose the time delta between master and slave can be queried, but that still doesn't protect from race conditions/inconsistent reads. This is actually why we chose to only utilize slaves for data redundancy rather than read throughput at my last company. Inconsistent reads weren't tolerable.

<comment><USER11> Riak does. You say, when writing, "please don't return until this data is replicated on 2 servers." And when reading, "please only return a successful read if this data is read from 2 servers."

So you have R = 2, W = 2, R+W = 4, and if your replication (N) val is 3, you're fine (you're always going to get consistency if R+W > N).

Riak is cool.

<comment><USER12> I believe Cassandra does as well, not 100% sure though.

<comment><USER13> Cassandra does, you can write with a write consistency of W and read with a read consistency of R, and as long as their sum is greater than the replication factor (number of copies to store across the cluster) you have consistent reads. W + R > N.

[http://wiki.apache.org/cassandra/ArchitectureOverview#line-1...](http://wiki.apache.org/cassandra/ArchitectureOverview#line-190)

</comment></comment></comment></comment></comment><comment><USER14> >Range queries are indexed differently

If I'm reading your description right, this is hardly mongo-specific. Try it in mysql, for example:

(index is [:last, :first])

      select first from names
      where last in ('gordon','holmes','watson')
      order by first;

An index is an ordering by which a search may be performed - to illustrate, the index for my small table looks pretty much like this:

      gordon, jeff
      holmes, mycroft
      holmes, sherlock
      watson, john

Unless the first key is restricted to a single value, it can't order by the second key without performing at least a merge-sort. They aren't _in_ that order in the index.

<comment><USER15> He never said it was mongo specific

<comment><USER14> >Things I wish I knew about MongoDB a year ago

The post reads as a series of criticisms about mongo. I don't love mongo, but I'm not aware of _any_ data store that can perform that type of query purely from an index.

Now, the description was vague enough that he could have been describing a real bug I'm not aware of - at one point I've seen MySQL decide to use an index for sorting instead of for filtering when that query plan was 500x slower. If mongo has a bug like that one, disregard my comment please. :-)

</comment></comment></comment><comment><USER16> One thing I love MongoDB for is it's geospatial indexing abilities: <http://www.mongodb.org/display/DOCS/Geospatial+Indexing>

Was a really nice surprise when I was building a location based web app.

<comment><USER17> That was our use-case as well. And it works fine for this but just in the application layer. We are not using Mongo for data storage (at least we are not trusting it to hold it for long)

</comment></comment><comment><USER18> Is MongoDB more marketing hype than quality product? I've heard it before and this article seems to point in that direction as well.

<comment><USER19> I think it's generally full of gotchas similar to that of SQL databases like MySQL and Oracle. In fact, most of the issues mentioned in this article, like delayed replication, indexed queries and using 'explain' are issues I've had to deal with in MySQL and Oracle. Most of these databases are fine out of the box for small scale use, but when you scale up you have to deal with these 'gotchas' like indexing, partitioning, bulk loading, and having to profile everything etc.

</comment></comment><comment><USER20> I wish I knew that it sucked.</comment>


Is Constant Corporate Monitoring Killing Morale? - <AUTHOR> https://www.nbcnews.com/better/business/constant-corporate-monitoring-killing-morale-ncna800301 <comment><USER2> Not really. Constant presence of politics and companies not caring about their employees' well-being and professional growth are what is killing morale. Everything else is just a minor pain compared to that.</comment>


HowTo: Google Authenticator as a virtual MFA Device on the AWS Console  - <AUTHOR> http://full360.com/blogs/use-google-authenticator-amazon-aws-console

<comment><USER2> This works really well, and is a good motivation for adopting IAM. Our shop has a number of people that need access to the AWS console and in only a couple hours we got this setup for everybody.

Now when people leave the company we just revoke their IAM account and they lose access, instead of having to change the master password over and over and communicate the new pass to everybody.

</comment><comment><USER3> MFA = multi-factor authentication.

That TLA was new to me.

<comment><AUTHOR> Ha I tried putting the full set of words in but hit the title limit

</comment></comment><comment><USER4> You can also enable it for the account you are currently logged on as via the front page of IAM in the console.</comment>


Where Is the Roommate Capital of the United States? - <AUTHOR> http://priceonomics.com/where-is-the-roommate-capital-of-the-united-states/ <comment><USER2> [https://news.ycombinator.com/item?id=10624759](https://news.ycombinator.com/item?id=10624759)</comment>


Quinnspiracy Theory: The Five Guys Saga - <AUTHOR> https://www.youtube.com/watch?v=C5-51PfwI3M

<comment><USER2> Yuck. While there might be a tiny sliver of a journalistic integrity accusation amidst the noise, this video was a tornado of slut-shaming. I feel gross now.

<comment><AUTHOR> Sleeping to get ahead in life is just fine and dandy, then? Just because you call it slut-shaming doesn't make it OK to cheat on your boyfriend and sleep with five guys. And that she did it to further her career goals is even worse.

</comment></comment><comment><USER3> Absolutely disgusting, that woman is.</comment>


How not to do your app's promo video - <AUTHOR> http://www.penboard.ink/promo.html

<comment><USER2> I don't know, that gave me a good laugh.</comment>


From The Past To The Future: Tim Sweeney Talks - <AUTHOR> http://www.gamasutra.com/view/feature/4035/from_the_past_to_the_future_tim_.php

<comment><USER2> " "After that realization about the web, I felt really idiotic. It forced me to be in the mindset of "Everything I do from now on needs to be thought through carefully." With every major technical problem, I didn't just look at "What is the problem I'm trying to solve?", but I took a much bigger perspective: "How can we really change the game and win this?"

When it came to developing Unreal -- I think we started that in 1994 -- James Schmalz was writing a solo assembly language 3D game with a dragon flying over a terrain, kind of a Magic Carpet knock-off. And I was tasked with writing the editor for it.

But I really thought that through in a huge amount of depth in advance -- you know, looking at what Quake did and Doom did: they had this little crappy editor with a very advanced game engine behind it. Completely separate programs.

I thought it through in a whole lot of detail, and I thought that content development was really the essential ingredient in all of that. It was important to spend even more effort on the editor and tools than the actual game itself, just to empower the artists to make a great game.

So we came up with this editor-centric approach to game development, where you had this integrated editor that used the game engine for real-time display of everything. Real-time editing of everything, and all of that. And that came from really methodically thinking through the problem of "What do you really do, and how do I not miss the point in this revolution?" "

Inspiring!</comment>


The fundamental problems with CSS3 - <AUTHOR> http://ajaxian.com/archives/the-fundamental-problems-with-css3 <comment><USER2> Actual article: <http://mattwilcox.net/archive/entry/id/1031/>

</comment><comment><USER3> Left out "Lack of support in IE6".</comment>


Ask HN: Why do people comment on an article? - <AUTHOR> Bloggers have a different motivation to blog than a commenter to comment. We have heard of "top bloggers" but have we heard of "top commenters"?
My questions are
1. Why do people comment on an article?
2. Why do they invest time in doing something, which they may not be able to retrieve later on? <comment><USER2> Sometimes I have something to say that I think people will find helpful. Sometimes people reply to my comments with useful information.

Feedback is important for everyone.

<comment><AUTHOR> Do you think it should be easier for you to retrieve this feedback?

<comment><USER2> It'd be nice if HN let me know when someone responds to my comments, though there are 3rd party tools for this purpose. Otherwise I'm not exactly sure what you mean.</comment></comment></comment>


Can Celiac Disease Affect the Brain? - <AUTHOR> http://www.nytimes.com/2014/10/12/opinion/sunday/can-celiac-disease-affect-the-brain.html

<comment><USER2> We discussed an earlier article by this author once before on Hacker News, which I recall submitting. I was actually embarrassed after submitting the article to find out that the author pushes his guesses beyond what current research shows and that scientists who work on the same problems mostly don't endorse his conclusions. You'll note, as I should have noted last time, that this New York Times column is an OPINION column, not a reporter's article about established facts. If you read this opinion piece the same way that Malcolm Gladwell encourages his readers to read his essays (as a prompt for further thinking, not claiming that he has the last word), then maybe no harm, no foul, but please be wary of making important health decisions for yourself without gathering second opinions on ideas like this.

<comment><USER3> That this is an opinion piece is made obvious by Betteridge's Law:

> "Any headline which ends in a question mark can be answered by the word no."

[https://en.wikipedia.org/wiki/Betteridge's_law_of_headlines](https://en.wikipedia.org/wiki/Betteridge's_law_of_headlines)

<comment><USER2> I recall that "Betteridge's Law," which I see from the Wikipedia citations is a new and not particularly widespread idea, was promoted here in the Hacker News community by the site founder and former chief site curator, pg (Paul Graham). While I will agree with the proposition that many articles titled with a yes/no question invite the easy answer no, I don't think that is an invariant property of all such articles. I think it's too cheap and easy on the part of the learned readers here to simply invoke "Betteridge's Law" without reading an article deeply and grappling with more of the article's argument than the article's headline. (That's especially true because sometimes headlines are chosen by editors of a publication, while the text of the article is chosen by the article's author.) I've already indicated that I am not sure I should accept the argument of this article (which brings up issues that are already familiar to me from other reading), but I also am very sure that we shouldn't dismiss every article submitted here with a yes/no question in its title before we read the fine article.

<comment><USER4> I think it's more of a joke "law" meant to discourage lazy click-bait headline-writing.

</comment></comment></comment></comment><comment><USER5> One of the quoted scientists, Dr. Fasano, discovered a protein called zonulin [1] responsible for mediating the permeability of cells in the gut, with possible implications for gut-involved autoimmune diseases. He authored a fascinating (so far, it's long!) review article on the subject, freely accessible [2].

The original article hints at one potential etiology for gluten's neurological effects:

 _antibodies directed at gliadin, a gluten protein, could cross-react with proteins in the brain. The finding suggests that, by some coincidence, certain proteins on neurons structurally resemble proteins in wheat. Meaning that, if your immune system attacks gluten, it might also inadvertently pursue brain tissue._

Interestingly, gliadin also activates the zonulin pathway. There is drug trial underway to target that pathway, now reportedly past the phase 2 (efficacy and safety) stage in 300 patients [3].

Another possible neurological tie-in is myelin. Myelin is a lipid sheath surrounding axons, very roughly analogous to cable insulation. De-myelination is involved in several autoimmune neurological diseases, including multiple- sclerosis. There are several proposed mechanisms referenced in [2], and recent work has suggested at least a weak association between celiac disease and multiple-sclerosis [4]. Since the original article also mentions schizophrenia, it is worth pointing out that de-myelination has also been suggested as a factor in some schizophrenic pathologies.

[1] [http://en.wikipedia.org/wiki/Zonulin](http://en.wikipedia.org/wiki/Zonulin) [2] [http://physrev.physiology.org/content/91/1/151.long](http://physrev.physiology.org/content/91/1/151.long) [3] [http://www.prnewswire.com/news-releases/alba-therapeutics- an...](http://www.prnewswire.com/news-releases/alba-therapeutics-announces- positive-results-of-phase-iib-trial-in-celiac-disease-244877451.html) [4] [http://www.biomedcentral.com/1471-2377/11/31](http://www.biomedcentral.com/1471-2377/11/31)

</comment><comment><USER6> My girlfriend has Celiac's disease, and she was diagnosed about 3 months after we started dating. Before her diagnosis I often wondered if she had some sort of mental illness because she would always describe having out-of-body experiences where she subjectively witnessed herself doing things in third person.

After she was diagnosed and went gluten free, there was an acute "rebound" phase where she had very painful rashes like the article mentions. But she also had a lot more energy and no longer slept 12 hours a day. The symptoms that made me worry about mental illness completely went away within a few weeks of her going gluten free.

This is all anecdotal but it seems very plausible that gluten can cause brain lesions in those with Celiac's.

<comment><USER7> As a fellow coeliac I have also had those experiences, no idea what caused them but they went away with the gluten free diet.

After being gluten free for 10 years now it's so easy to tell when I've eaten something that contains gluten.

</comment></comment><comment><USER8> The idea's unfortunately been picked up by the fringier side of the discussion, but there's evidence that some proteins in wheat (not just gluten) trigger opiate receptors in the brain.

\- [http://www.ncbi.nlm.nih.gov/pubmed/1309704](http://www.ncbi.nlm.nih.gov/pubmed/1309704)

\- [http://www.ncbi.nlm.nih.gov/pubmed/6099562](http://www.ncbi.nlm.nih.gov/pubmed/6099562)

</comment><comment><USER9> Some suggest that avoiding gluten is a good idea with other autoimmune diseases too.

<comment><USER10> Could you point me to some sources? I'm very interested in this.

<comment><USER9> Sorry I am answering late.

One is this author suggesting removal of Gluten for MS: [http://www.jandevrieshealth.co.uk/health_matters.asp?int_ser...](http://www.jandevrieshealth.co.uk/health_matters.asp?int_service_id=58)

There is [http://www.ncbi.nlm.nih.gov/pubmed/20170845](http://www.ncbi.nlm.nih.gov/pubmed/20170845) but it is apparently controversial(?)

<comment><USER10> No apology needed! Thanks so much for digging up some info. I have a family member struggling with an autoimmune disease and any bit of info I can work with is helpful.</comment></comment></comment></comment>


Ask HN: What should I build? - <AUTHOR>

That pretty much what I wanna ask you guys. What should I build? I am bored to my bones. Suggest a project, if you will.<p>EDIT: I am Python/Erlang/C dev who has done a bit of Android and iOS dev. My email is my username at gmail. Dont ask me to make beautiful games, I am sure I wont be able to do that. <comment><USER2> There are Kaggle contest if you want to get into data. You can also search for social hackathons if you want to do some good for the world. You can go outside and talk to people, listen to their problems and use your programming skills to solve them. You can build tools to solve your pain points. You can try to take classes on Udacity and Cousera to see if you get any inspiration for projects. Maybe make some contributions to opens source projects. Games don't have to be beautiful, look at Minecraft. There are a lot of tutorials online about making 3D models, illustrator, etc. You only get better at things by doing them.

</comment><comment><USER3> Just sent you a gtalk connect request - from my username at gmail dot com Id be happy to show you what my little bootstrapped team is building, though actually, we need mysql and backend php.

</comment><comment><USER4> Name your preferred domains and interest areas. BTW it's best to scratch your own itch.

Maybe you should build sumting that relives you of your boredom. Maybe the next angry birds ?

<comment><AUTHOR> I am not much into game programming. I edited the post to reflect that. Do you have any suggestion?

<comment><USER4> in the middle of writing you a mail.

</comment></comment></comment><comment><USER5> A daily email digest of HN, sent to the user on a specific time he/she wishes, with all of the links (including Ask HN), sorted by points.

<comment><USER6> Mostly done already via <http://www.hackernewsletter.com/>

<comment><USER5> Isn't that weekly? It'd be cool to have a daily one.

</comment></comment></comment><comment><USER7> Please develop a mobile app for my web app <http://weekplan.net> The web app userbase is growing and I can't keep up with the development.

There is already an API although it is not documented yet. Contact me if you are interested.

</comment><comment><USER8> I wrote <http://hirehub.me> on side, its getting traction in India. You can contact me if you would like to contribute. I have made it mostly for startup, because startups cannot afford high prices.

P.S Built completely in Rails

</comment><comment><USER9> I'd love to see a mobile game for couples that is asynchronous and collaborative.

</comment><comment><USER10> I was asked over the weekend if I knew someone who could build an app to run on Android and iPhone. Not a game, but a data-gathering, easy-to-use app.

My email is in my profile.

</comment><comment><USER6> Are you interested in working with others or just want to do something solo? I have some ideas, but obviously I'd like to be involved somewhat.

<comment><AUTHOR> Either. Tell me what do you have in mind?

</comment></comment><comment><USER11> You should add an email to your profile, that way people can reach you :)

<comment><AUTHOR> My email is my username at gmail

</comment></comment><comment><USER12> a chrome /firefox plugin that finds plain text links (without <a> tags) Easy and pretty usable instead of highlighting copy -> paste the url or email. If you don't make I will :D

<comment><AUTHOR> :) That should be an hour spent well

</comment></comment><comment><AUTHOR> Someone upvote this so more people can see it and reply

</comment><comment><USER13> same problem with TS, looking for a side project. I write Perl/Python(Flask).

</comment><comment><USER14> an erlang IDE.</comment>


Ask HN: How to Process Millions of SVG to PDF - <AUTHOR> We're building an API in Django that's responsible for converting millions of SVG images to PDF. The current implementation is slow where tens of thousands could take hours and I am wondering if you have experience with a low level library that could improve the performance <comment><USER2> Depends entirely on your setup but this work seems a good fit for a job queue where you can spread the work over multiple machines and processes.

I believe celery has integrations for Django.</comment>


Google Experiments – Paper Phone - <AUTHOR> https://experiments.withgoogle.com/paper-phone <comment><USER2> ROFL, cute! :-)

I started watching the video with a snarky expectation of "aka a book", but it's nice how:

1\. The contents are personalized and time specialized (Eg: today's tasks and maps).

2\. There is _no infinite scroll_ or _pull to refresh_! Which means that you avoid the worst of your addictive behavior, and have a chance to be present in the real world, because your phone only has a few things that you need to catch up with.

Now, suppose we wish to avoid using paper. We could get something equally good by just disconnecting from the internet and allowing apps only a small cache — if apps were willing to cooperate.

The only reason that won't work is because apps are in a zero-sum race to the bottom to hog user attention. So, the abundance ("hot" according to McLuhan) of the networked electronic medium (color/interactive media, and effectively infinite content) becomes a firehose that is turned against the user. The only role of paper in this idea is to impose constraints — b/w printing, non- interactive and 2 pages of content.

It is very interesting how the key value add seems to be _reintroducing_ constraints i.e. "scarcity". Who would've thunk?!

<comment><USER3> > The only reason that won't work is because apps are in a zero-sum race to > the bottom to hog user attention.

I don't think this is entirely true. If micro payments worked, or if you have some kind of subscription model, you don't want people to use your app as much as possible (the more they use it the higher your costs), you just want them to find it so useful that they keep updating/subscribing to it.

> The only role of paper in this idea is to impose constraints

While I do love constraints, I don't think that's the whole point. Paper is superior to screens in a number of ways. For a given piece of information, it's much more convenient and readable, it's just not interactive.

</comment></comment><comment><USER4> I recently laser cut a "Pixel 4 XL" in acrylic to see if I liked the form factor before considering it. I put my other phone in my desk for a day and just carried around this brick of plastic where my phone usually goes. The XL form factor is alright, but I really loved just fidgeting with a phone-like form, flipping it in my hand, putting it in my pocket, all without any notification buzzes or unread emails.

</comment><comment><USER5> To break habits it should have the same form factor as a phone case. Even better if it was a reloadable flipbook phonecase with super-thin paper.

If you can swipe through the flipbook you'd get a similar feeling as using a phone but because it wouldn't be infinite you'd stop after getting to the end. Allow yourself to reload X amount of times per day and it'd be the perfect way to break addictive phone use habits.

</comment><comment><USER6> I was expecting a scroll of paper fitted into a phone shaped box or something, such that you could literally scroll it.

That was still interesting, the title alone got me excited and thinking 'what could it be?'

</comment><comment><USER7> Maybe at a few spaced intervals a list of the texts received could be printed, with blanks in which to handwrite responses, to feed back in somehow later.

Lots of fun possibilities.

</comment><comment><USER3> Fun idea, could work if combined with a dumb phone, or an apple watch. The only problem is you know they will eventually fill the book with ads...</comment>


If Go To statements are bad then why ... - <AUTHOR> ... are there countless abstractions and programming language mechanisms that bounce you around the text in ways that Go TO could have never dreamed of. I rarely spend time thinking about stuff like this but sometimes, just sometimes, the question just begs to be asked (again). <comment><USER2> > _... are there countless abstractions and programming language mechanisms > that bounce you around the text in ways that Go TO could have never dreamed > of._

Like? What are those abstractions and mechanisms?

Well written programs can (and do) make use of no such mechanisms, in any case. Where have you seen those? Any particular example that moves the flow the way Goto does?

Exceptions come to mind, and people always point out that its bad to abuse exceptions for control flow (e.g. using them like a kind of goto).

The problem with goto (which is not considered a problem when used in local scope, e.g. for cleanup code within a function) is that it moves the flow of execution away and makes it difficult to track.

A function (or e.g. a continuation in Node) doesn't have that problem: you return back to where you started.

</comment><comment><USER3> Flow of control is what is critical in every application, and goto's allow you to break flow of control easily. That said, a lot of very stable systems used goto's for very specific instances. For example, they would use it to short circuit the if/else/if/else for error handling, cleanup etc. But it was a goto within a single scope, e.g. within a single function. Of course, with that power comes the ability to cut off an important appendage, and in reality the "need" for a goto is really not a need, it is a lazy implementation detail.

Usually what I found is people feeling the need to use goto often just didn't understand how to design or layout the system they were working on, or try to put to many unrelated code segments into a function. As other comments mention, the flow of control changing scope etc cause lead to all kinds of difficult debugging, memory leaks, crashes etc. So not generally a good idea. Smarter to use proper function scoping, return behavior and error codes.

One of my early tasks as a C programmer, back in the early 90's, was taking a C program that had like only 4-5 functions (with thousands of lines of code) in it, and tons of goto's and cleaning it up to be a maintainable system. Engineers all hated that system because it ran fairly stable (somehow), but touching a single line of code could mean days of debugging. Starting over was easiest but took forever to get the functionality correct because of all the jumps to weird places that were not obvious behaviors. That was an unforgettable lesson for me.

</comment><comment><USER4> Jumping between addresses is the way how assembler programs/machine code works. A high level language shall abstract, bringing powerful concepts like scopes. If you short-circuit the high level logic by directly using gotos, you will shoot into your foot. Furthermore, the pladoyer "goto considered harmful" was about using high level program structures for the sake of their power. Letting the compiler alone to do the hard work of managing your variables, etc.

</comment><comment><USER5> I once failed/bailed from a C course because I refused to remove a `goto` and the instructor refused to allow my code to be submitted. Even though it was demonstrably the right thing to do, he was adamant that it was better to have a cascade of `if` blocks with guard variables that made it way more complex and difficult to follow.</comment>


Usage Statistics of Linux for Websites - <AUTHOR> https://w3techs.com/technologies/details/os-linux <comment><USER2> Something seems really off about the "statistics" presented here. For instance, 71.3% of all websites "use Unix". Honestly, that seems really high in these days of Solaris, AIX and HP-UX effectively disappearing. x86_64 rack hardware is super cheap, and Linux is almost free, unless you really, really want to pay for it.</comment>


Firefox rises from ashes of abandoned Netscape - <AUTHOR> http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2008/01/28/BULFULUNF.DTL <comment><AUTHOR> "Victory goes to the organization that can put together the largest consortium of brains,"</comment>


What was your greatest growth hack? - <AUTHOR> What hack did you create that helped increase engagement and visitors to your platform? <comment><USER3> We were selling a product to outbound telemarketers. So I bought a bunch of secondary phones for our sales guys, and pumped those numbers into every data list we could find... prize draws... surveys... etc.

They were flooded with telemarketers. And if they spotted an issue (bad quality audio... big gaps at the beginning of call.. and so on) they would open up and insist the telemarketer help them get in touch with a manager so they could help improve things.

We had a spike of sales during that period, before the chaos of managing these phones meant we had to stop. :)

</comment><comment><USER4> Make something good that people want to use? If your product/service is that hard to sell to begin with your time would probably be better spent on development than growth hacking.

<comment><USER5> That's a really naive response because it assumes the product is already in people's hands. Distribution is one of the biggest challenges that startups face. Also you can't create something that people love with an MVP for every idea. The original iPhone took $2b to develop. Think they could have made something people love with $10m? Probably not. Some problems are hard, and if you're bootstrapping with an MVP you need to iterate toward product market fit which means you need feedback which comes back to distribution.

<comment><USER4> And how much did Apple have to spend marketing the iPhone? The iPhone was useful. It sold itself. Nobody had to be convinced. Good products and services don't depend on marketing to be successful. If it's that hard of a sell there's probably a reason.

<comment><USER6> >And how much did Apple have to spend marketing the iPhone?

You're joking, right? Even after 10 years they're STILL spending a lot on advertising it.

<comment><USER4> Ok I think we're talking past each other. I was busy earlier so I didn't get a chance to fully respond. The point I was trying to make about the iPhone and marketing was the bulk of money and time invested was in the product itself. You said Apple spent 2 billion in R&D. Now how does that cost compare to the marketing campaign that followed? I found this article talking about advertising for the iPhone 6:

[http://www.campaignlive.com/article/apple-ad-spend- rises-50-...](http://www.campaignlive.com/article/apple-ad-spend- rises-50-record-18-billion/1370742)

"The company reported record profits of $53.4 billion on turnover of $233.7 billion, thanks to the iPhone6 and iPhone6s sales. Advertising still represents less than 1% of turnover."

Do they spend a crapton on marketing? Well compared to how much me and you make, yes. But compared to what Apple makes off iPhones, it isn't. The point I was trying to make was the iPhone successful because of a slick marketing campaign or was it the quality of the product itself? I would say it's the product in this case. Look at high-traffic sites like reddit and imgur that barely market themselves but are still wildly popular. Why? People like it and want to use it because they're good sites. That was the point I was trying to make. A good product or service is worth it's weight in marketing gold. In my opinion you should be spending the bulk of your resources on R&D improving your product than growth hacking. Your chances of success are much higher with a solid product/service. The tech industry has an abysmal failure rate compared to literally any other industry and I feel this trend of rushing through a MVP and marketing the hell out of what's essentially an unfinished product is the cause. How do you even know if the market for your product or service is even there to begin with if your MVP isn't fully functional yet. Concentrate on the product/service and beta test. Get feedback and listen to what people are telling you. Grow organically. Maybe people likes how your product does X but but starts asking if it could do Y also. The addition of that feature could be what pushes your product over the top. That's all I was saying.

</comment></comment></comment></comment></comment><comment><USER7> Not a growth hacker, so not sure if this is an idea/insight you'd be looking for.

Here's mine:

Asking right people the right questions help. I asked my favorite game- designer about Buddhist meditation (I noticed she's into that as am I), she retweeted it to her 100000 followers.

My Twitter account has 0 followers (or 1) and back then it didn't even have a profile picture.

So asking the right questions :)

</comment><comment><USER8> Not mine, but my wife signed up for Nextdoor several years ago. They send a postcard verification of address like Google Maps does for businesses.

She found out that all of our neighbors got a postcard inviting them to Nextdoor and it said something like "[So and So] just joined Nextdoor and invites you to join!"

She never opted into this knowingly but I'm assuming it was in the terms somewhere. I thought it was brilliant for acquisition; maybe one of the best strategies I've seen.

<comment><USER9> I think the users privacy should count for something. This is a betrayal in my book.

<comment><USER8> It was probably somewhere in the terms. Not ideal, but at the same time - <USER2> product IS a social network for the neighborhood, so the user gets value from having their neighbors on. And they expect to have their neighbors on.

I'd prefer a checkbox with one line of text saying they would use my name though.

</comment></comment></comment><comment><USER10> Not mine, but I know that one of the main bottled water sellers in Chile dropped lots of empty bottles regularly at different kinds of trash containers in places where people that looked at it could associate the brand with "successful" people. It worked very well.

</comment><comment><USER11> I released my ebook about Bootstrap 3 for complete beginners on 2013/09

Being an ebook, it peaked in the first 5 days and by December it was bombing as expected.

I did a "holiday sale" with discounted prices as planned, and announced it for 12/24 till 12/31\. Sales immediately went up and right like there was no tomorrow.

Then I purposely _forgot_ to restore the original prices until 01/20 and people just kept buying it, thinking they were oh-so-smart for taking advantage of me.

On 01/21 I restored the original prices and went back to close to no-sales at all.

Given the cost to produce another copy of what I was selling is zero, I'd say that was a very big win.

<comment><USER12> > On 01/21 I restored the original prices and went back to close to no-sales > at all.

How come you didn't continue with the discount then? Seems like you just put the nail in the coffin right then and there.

<comment><USER11> I had another deal with a third-party site coming in March and was afraid to completely burn the thing :)

</comment></comment></comment><comment><USER13> Not mine. But it's hard to top "Hiding $10k in fake vaginas buried on the beach" for quick and dirty PR...

[http://www.myviralsecrets.com/](http://www.myviralsecrets.com/)

</comment><comment><USER14> \- Had a trivia game. You would be able to play only 4 turns a day. If you wanted to continue, you would need to invite your friends or ask turns from your friends. We would receive more than a thousand requests each day and it went viral.

\- Had a chat website. It would let you create a profile and let your friends ask you questions anonymously. You needed to share your profile on social media to let people know that you are online. They did and it went viral.

</comment><comment><USER15> At Vinty (drivevinty.com) we work very hard to provide excellent service. This tends to have the effect of people referring us to their friends.

</comment><comment><USER16> My friend was working on admin theme for themeforest for 6 month but admins didn't aprove his theme. What he did?

He made it opensource! And got 2000+ stars on github in one month. 6 month leter he has 7000 stars on github that turn into 2 big clients and a lot of $$$

Take for example Buffer. They created 2 Free relevant products for their field to create buzz around Buffer, ex pablo.buffer.com

</comment><comment><USER5> Back story. We launched www.agfunder.com as an angellist for ag tech startups with the vision of later including any company in the sector of any maturity. At the time there was no ecosystem and when you said the word 'agtech' everyone assumed you said 'adtech'. When we first launched we hired PR and worked with them to get converse along the usual channels: TechCrunch, WSJ, NYT, and doezens of other tech and ag blogs. The result: crickets. Good luck launching a two-sided marketplace without distribution. Today we have over 30,000 members and subscribers including 4,000 investors, we've have helped companies raise over $35m, and we've become one of the central entities in the emerging agrifood tech ecosystem. Later this year we'll be announcing a $20m investment vehicle we've raised almost entirely from our network of institutional and individual investors. This is how we did it:

(1) Started aggregating and rebroadcasting relevant news and media with our Twitter account. We also addded thousands of people who we thought would be relevant as about 10-20% of people at that time would follow back.

(2) Admittedly a bit of a dark pattern even in 2013 (and certainly has been done independsntly), but when we launched our site we needed distribution. So in desperation I did domain targeted keyword searches on LinkedIn and added about 5,000 people (with about a 30% accept rate). I was shocked to find that LinkedIn didn't really rate limit (I had one warning, but upgraddd my account which seemed to placate them). I then exported this list for our first email distribution list (We were getting a respectable 20% open rate).

(2.1) I then repeated, adding speakers from relevant conferences.

(2.2) Realizing that I couldn't add many more people to LinkedIn without getting flagged and worrying about the hygiene of our domain name to spam filters, we went to the library to use their Reuters accounts and combed financial databases for investor emails, parsed those lists. Rather than uploading the raw list to our email list we instead added this list to my contact list and then synced with LinkedIn, using LinkedIn as a filter to identify people who might be interested in what we were doing. LinkedIn will not flag you if you mport a contact list if those people do not accept the request.

(3) Next we produced a great easy-to-scan weekly newsletter, originally just aggregating top content we were retweeting. Today we have a 30-35% open rate with 60% opening in the last month and 90% in the last year.

(4) That same year we started publishing www.agfundernews.com which we dubbed the TechCrunch for food and ag. Since then we've published over 1,000 articles and have had over 100 expert contributors. At this point all roads lead to AgFunder.

(4.1) We decided to give this a unique URL because we were hoping we could get into Google News (never accepted after multiple attempts and all the while becoming the industries main news blog) and also because it was easier to get interviews when we pitched it as AgFunderNews.com rather than AgFunder.com/news which feels more like a blog. If you spend 15 minutes searching for ag/foodtech you're bound to come across us.

(5) As interviews started to trickle in, each time I would faithfully update my LinkedIn profile knowing that journalists are going to respond to social proof as they're looking for sources. I've been interviewed for TechCrunch, Bloomberg TV, CNBC, WSJ, Forbes and more. Lot's of people discover us from the media.

(6) In 2014 we did a short investment overview of the sector and then in 2015 we spent a month aggregating and curating data for a full 60 page industry report. This report has been a magnet for startups, investors, and media. It's a proof of work quality that builds trust over time. Our research pages are the second most visited pages on our site (top of the funnel).

(7) In 2015 we also added a pop up email newsletter subscription form. Say what you like, but top of the funnel registrations quadrupled in a week and have been growing ever since.</comment>