A tall chimney to facilitate heat exchange in the atmosphere - <AUTHOR> http://www.superchimney.org <comment><USER3> For those skeptical of the science, note that there are large caves that exhibit this property, such as: [https://en.wikipedia.org/wiki/P%C4%B1narg%C3%B6z%C3%BC_Cave#...](https://en.wikipedia.org/wiki/P%C4%B1narg%C3%B6z%C3%BC_Cave#Wind)

It seems like if the inside of the chimney column had a spiral shape, similar to a screw socket, the upward air pressure might alleviate some of the stress and make the column more structurally feasible. Granted, it would also dissipate some of the energy as heat.

<comment><USER4> Caves like that presumably connect two areas of air that are not otherwise connected, and not in equilibrium with each other, no?

Unless I'm missing something, TFA suggests that you can take a big system that's generally in equilibrium, and run a tube from one part to another, and get a similar effect. This seems like a very different proposition from what's happening in caves like you mention.

<comment><USER5> The atmosphere is emphatically _not_ in equilibrium. Why would you think it was? There's a giant fusion engine pumping energy into it, resulting in a fuck of a lot of activity (wind).

In particular, the upper atmosphere would not be colder than the lower if it was at equilibrium. Think about it.

<comment><USER4> I didn't say the system was closed. Why would you think I did? All I meant was that energy is free to flow around the atmosphere if it wants to; any macroscopic flow that wanted to occur would have occurred already.

In other words, caves like the GP mentioned (presumably) connect two systems between which energy is not otherwise free to move. That is not the case for a tube connecting two different sections of the atmosphere. Make sense?

> In particular, the upper atmosphere would not be colder than the lower if it > was at equilibrium. Think about it.

Temperature varies inversely with pressure for a volume of gas. If low- and high-atmosphere gas had the same temperature, despite being at different pressures, _that_ would be an imbalance.

</comment></comment></comment></comment><comment><USER6> This reminds me of Solar updraft tower prototypes [1], which concentrates heat at the bottom of the chimney instead of expecting cold air at the top of the chimney.

There's still a delta of temperature between the top and the bottom, but instead of

        T_bottom_chimney  = T_hot_ambient_air_bottom
        T_top_chimney     = T_cold_ambient_air_top

it is :

        T_bottom_chimney  = T_much_hotter_than_ambient_air_top
        T_top_chimney     = T_ambient_air_top

Everytime I start reading things like this, I wish I had a home with similar 'magic', like Solar chimneys[2] and other techniques[3],

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

[2] [https://en.wikipedia.org/wiki/Solar_chimney](https://en.wikipedia.org/wiki/Solar_chimney)

[3] [https://en.wikipedia.org/wiki/Ground- coupled_heat_exchanger](https://en.wikipedia.org/wiki/Ground- coupled_heat_exchanger)

<comment><USER7> They _almost_ got funding to build one that was going to be 1km high right next to my home town [1] in rural Australia.

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

Back in the day dad and I figured out we would easily see the tower from home, and the shadow would cross our house. Also it would be possible to see the curve of the earth from the top, so there was talk of allowing tourists up there.

<comment><USER8> Can you really see the curve of the earth from 1km? I can't really even see the curve of the earth from an airplane (or can people with 20/20 vision see the curve from commercial aviation altitudes?)

<comment><USER9> The declination of the horizon is a couple degrees at altitudes that commercial flights fly at. It can be measured with standard carpentry tools.

<comment><USER10> Now how did you get carpentry tools into an airplane?

<comment><USER11> Like this obviously: [https://www.youtube.com/watch?v=6nNUEU8gnf4](https://www.youtube.com/watch?v=6nNUEU8gnf4)

<comment><USER9> I can't tell if this is satire. We're well into Poe's Law territory here.

</comment></comment></comment></comment></comment></comment></comment><comment><USER12> So my question is "why wouldn't this just rip in half from the forces it's under?"

The upward force for the 20m chimney is calculated at ~600 tons. 600 tons is not a lot for a building to support in the downward direction, but quite a bit for a fabric tube to support, in tension. It's the rope/(space) elevator problem - you need a super material to handle that much force, don't you?

But aside from worrying that our wacky inflatable tube of death will rip free from its tethers and tumble freely in the wind, killing thousands, I actually really like this idea, as geo-engineering. It is a process that can be stopped and started relatively cheaply, unlike a lot of other proposals. If the tube has unforseen effects, it could be deflated and reeled in, unlike eg throwing particulate into the upper atmosphere.

<comment><USER13> Perhaps such a chimney could be built inside the shaft of a space elevator, canceling out the forces.

I'm only being half serious, but it is nevertheless interesting that the required structural challenges act in opposite directions.

</comment></comment><comment><USER14> So five kilometers of flailing inflatable tube man.

I get that the upwards wind force can sustain the fabric structure, but it is hard to imagine that it could also carry a bunch of huge turbines, as well as the cabling required to carry the generated electricity. Not to mention safety concerns. Does this seem unrealistic to anyone else?

Also, would it be possible to do a proof-of-concept using an existing man made structure like Burj Khalifa class skyscrapers? Presumably it would be easier to deploy a tube off the top of one of these than to build one from scratch.

<comment><USER15> The turbines are at the base of the mushroom; the rest of the structure will essentially be a giant tube man as you said

</comment></comment><comment><USER16> "The inside and outside air will be rising up. However, the air outside will be cooling adiabatically, so its temperature will be dropping. The air inside will be not affected by adiabatic cooling and will maintain its energy, so it will be warmer and less dense than outside air."

Is this a joke, or a crazy person? Air in the tube will expand and cool just like air outside the tube does.

<comment><USER17> If you can bootstrap the thing at all, the air in the tube can only expand and cool by going up the tube. If it expands at the base, it runs into air at the same pressure. If it didn't already have upward momentum, that might be the end of it, but if it's already moving upward into a region where the outside temp/pressure is lower, if it tries to expand, it can only do so upwards. Since air inflow at the bottom has to equal air out the top in equilibrium, that expansion can only push air through the tube faster, which helps the concept's viability. Granted, this is a slightly different theory of operation, but it uses the same basic logic of exploiting the pressure difference by limiting the ability of the air to expand freely.

He does say a lot of things that are goofy (you can't just assume the outside air is rising, still air is a thing that happens), and the theory I'm putting forward is a bit different than his, but I'm just saying I'm not sure you can dismiss the whole concept on thermodynamic grounds. IANAPhysicist, so I'm open to clarification on any point.

<comment><USER16> Air will accelerate as it moves up the tube, but that doesn't do anything useful for us. If the pressure drops in half then your speed will double, so a 1m/s inflow produces a 2m/s outflow, but you can't exploit that to produce energy. Or rather you can, but only by slowing the flow. You'll either slow it to a stop, or you need a source of heat to keep it going.

<comment><USER18> There is a source of heat -- the sunlit Earth.

It sounds like the basic idea is to get that hot air off the surface where it can radiate energy to space with less reabsorption.

I agree that extracting work for power generation would limit the amount of air that's moved, so there's a tradeoff you'd have to make.

<comment><USER16> Part of the idea is that the tower supports itself on the venting air, which means it has to be running non-stop. Even at night, when there's no sunlit Earth to drive it.

Yes, there are many days where a structure like this could operate for several hours off of solar heating. But that's not what's being described here.

<comment><USER3> If you do some mountaineering, you'll notice that the elevation temperature difference is persistent day and night. It is always cooler higher up at the desert latitudes described. If the sun stopped shining for a few days, then yes, the surface temperature differential would produce less and less potential.

This idea requires some creativity, but it's among the most interesting I've heard. And the science that you question is definitely sound -- the only real issue I see is finding a material to handle the stresses.

<comment><USER16> If you do some glider flying, you'll notice that atmospheric convection almost always stops well before sunset.

Yes, it's almost always cooler at higher altitudes. That's because air pressure is lower, making the air less dense. When air expands, it cools.

Because of this, merely having warm air below cold air isn't enough to make the warm air buoyant. The temperature difference needs to be big enough that it will _still be_ warmer when it has risen to the altitude of the cold air and expanded to match the pressure there.

To state it with some jargon, the temperature difference must exceed the altitude difference multiplied by the adiabatic lapse rate, otherwise the warm air doesn't go anywhere.

So: warm air at the bottom of the chimney will rise in the chimney if and only if the temperature at the top of the chimney is a _lot_ colder. For a 5km chimney with dry air (moisture complicates the numbers but doesn't change the principles at work), the temperature at the top needs to be 50°C lower than the temperature at the bottom just to be in equilibrium. In order for air at the bottom to experience any force upwards, it will need to be a fair bit _more_ than 50°C warmer than the air at the top.

The web site here says that this is not an issue because the air within the chimney does not experience adiabatic cooling as the air outside the chimney does. Which is complete nonsense.

<comment><USER3> > The web site here says that this is not an issue because the air within the > chimney does not experience adiabatic cooling as the air outside the chimney > does. Which is complete nonsense.

As I posted elsewhere, whether or not you can conceptualize it, there are real examples of this phenomenon in the world, such as this large cave network in Turkey. [https://en.wikipedia.org/wiki/P%C4%B1narg%C3%B6z%C3%BC_Cave#...](https://en.wikipedia.org/wiki/P%C4%B1narg%C3%B6z%C3%BC_Cave#Wind)

Even if the temperature differential needs to be a bit higher to make this consistently effective, there are certainly ways that can be done. Such as channeling heat via thermal conductors and radiative materials at night, or consuming waste heat from industrial processes that would be happening regardless. I think it's worth exploring.

<comment><USER16> I can't find much information about those caves, but I bet the wind isn't constant.

It's worth exploring chimneys, and indeed people are. It's not worth exploring chimneys which generate airflow 24/7 without a heat source because they magically suppress adiabatic cooling of the air within.

</comment></comment></comment></comment></comment></comment></comment></comment></comment><comment><USER19> If the column of air is really moving at 300 MPH, they'd better diffuse that at the bottom so people (and things) aren't sucked into the chimney (it would suck to be ejected at the top without a parachute but you could probably sell a ride to the top to the wing-suiters).

</comment><comment><USER20> Nice debunking write up here:

[http://climateboy.blogspot.com/2009/04/super-chimney-that- wi...](http://climateboy.blogspot.com/2009/04/super-chimney-that-will-save-us- all.html)

<comment><USER21> I don't find the debunking article persuasive. It says, "Imagine you take a blob of warm air from the surface up to some height... this transformation has to change the temperature of the air in the blob."

No it doesn't.

The nearest it gets to supporting that claim is, "It turns out to be very easy to derive an equation that says that the temperature decreases by 10 degrees C per about 1000 m of height with no vertical motion. That explains why the air above the surface is colder than the air at the surface."

I'd like to see the assumptions of deriving that equation. Without seeing how the equation is derived we can't jump straight to the "That explains why" part. I guess the equation he's talking about assumes the atmosphere is static and is simply deals with how the upper atmosphere is colder because it can radiate into space, whereas the lower atmosphere can only exchange radiation with warm ground or the cold-but-still-warmer-than-space upper atmosphere. If so, it says nothing about what happens when you "move a blob of warm air".

Maybe building these things is not feasible or maybe the effect is not significant, but it doesn't look physically impossible to me.

<comment><USER22> when any gas expands, it does work in expanding against the outside "surface" of the control volume, which comes from the internal energy - temperature - <USER2> the molecules.

The equations are commonly derived in thermodynamics undergrad courses. look up adiabatic expansion.

here's a video:

[https://www.youtube.com/watch?v=ObnWb7yspxA](https://www.youtube.com/watch?v=ObnWb7yspxA)

<comment><USER21> Good point. I stand corrected.

I still think that the radiating-into-space effect I mentioned is real. I imagine this is part of the reason there is convection in the atmosphere. But I'm out of my depth.

</comment></comment></comment></comment><comment><USER23> Anyone here could run a super tall chimney software simulation ?

I'm super interested in seeing someone confirm or debunk this. Anyone else interested, upvote please

<comment><USER24> Probably nearly impossible. Fluid dynamics simulations are horrendously time consuming even at low resolution and small scale. This is bound to be more of an engineering stunt than a scientific endeavor.

<comment><USER25> GPUs are dime a dozen these days.

<comment><USER26> We need ChimneyCoin!

<comment><USER27> We need a new Godwin's law for cryptocurrency.

</comment></comment></comment></comment></comment><comment><USER28> Engineering issues aside, to evaluate if a super chimney would be energetically viable you need to understand the concept of "Convective available potential energy" or CAPE--[https://en.wikipedia.org/wiki/Convective_available_potential...](https://en.wikipedia.org/wiki/Convective_available_potential_energy). CAPE has dimensions of energy/mass and a describes how much energy is released by raising a mass of air to some higher elevation.

CAPE is used to forecast storm development, as updrafts can more likely spontaneously form when there is more energy released by the updraft. CAPE values can also be zero or negative, in which case there would be no available energy to sustain an updraft. From my understanding, CAPE is the only factor that would determine if a super chimney could work at a given time.

I have not found a good resource on global CAPE patterns including daily patterns, but it seems very likely that there is any fixed location and fixed elevation that always has a positive CAPE value. It would be an absolute requirement to find such a location for this project to work.

You should also be able to calculate a crude bound on the maximum updraft velocity simply as a conversion of potential energy to kinetic energy. Wikipedia says that exceptionally high CAPE values proceeding extreme thunderstorms are around 5kj/kg, which would accelerate a mass from rest to 100m/s (220mph). Of course this is an extreme value, typical values are more like 1kj/kg, which correspond to a velocity of 44m/s (100mph).

Here is a really good paper on CAPE and atmospheric convection heat engines: [http://journals.ametsoc.org/doi/pdf/10.1175/1520-0469%281996...](http://journals.ametsoc.org/doi/pdf/10.1175/1520-0469%281996%29053%3C0572%3ANCAAHE%3E2.0.CO%3B2)

<comment><USER29> thank you

</comment></comment><comment><USER30> The short story "Shortstack" by Walt Richmond and Leigh Richmond depicts this idea and was published in Analog in '64\. Likely coincidental, but amusing to see '60s science fiction apparently made flesh.

<comment><USER31> The scifi novel "Omega" by Jack McDevitt also had this.

</comment></comment><comment><USER32> For the 5km chimney it needs to hold on 500km/h winds. For scale a category 5 hurricane is 250 km/h. Is it even possible to have that kind of structure with existing materials?

<comment><USER33> I'm not a real engineer, but most structures don't have the ability to flex like this tube could.

<comment><USER34> Rich Homie Quan couldn't even flex like this tube could. Making really tall stuff is hard.

</comment></comment></comment><comment><USER35> I've tried to simulate 1km chimney in Comsol, but I cannot make it converge to a solution. If anyone is interested, the model is here [https://mega.nz/#!jFgBxI6J!jdxloYFwcuk_YyGcIMlOmJTKcPbxyD2B4...](https://mega.nz/#!jFgBxI6J!jdxloYFwcuk_YyGcIMlOmJTKcPbxyD2B4Hvuo1OIoFM) (may be I'm doing something wrong with simulation parameters, help would be very much appreciated!)

<comment><USER36> I don't have Comsol. Does it make nice graphics? Can you post a screenshot (in imgur)?

[Disclaimer: I think this idea doesn't work. If you wish to make it work try adding a _huge_ glass bell like the one explained in other comment.]

<comment><USER35> Yes, it does, the problem is, the basic setup isn't converging to solution so nothing to plot, which is unusual and probably means I choose wrong boundary conditions or something.

</comment></comment></comment><comment><USER37> This will also function as a hell of a bird vacuum.

<comment><USER38> The input is at the ground level, and obviously you'd have grates and such to prevent things other than air being consumed.

<comment><USER38> (That's assuming the thing would work at all, which it wouldn't as far as I can tell.)

</comment></comment></comment><comment><USER33> Here's my analysis from maybe wrong principles. If you have slightly more dense air beneath slightly less dense air, the air will experience a net force upwards. If this net force is stronger than gravity, then the air will experience upwards acceleration. This will continue as long as there is a difference strong enough. At the top of the tube, there is no more force since the density will be the same since the air will spread out after exiting. (If it's not already at the same density after going through the tube).

Looking at it this way this seems sound to me, am I wrong?

<comment><USER39> It is a bit different than that.

Air is compressible. And because of that the mass of air that is being pulled toward Earth by the gravitational attraction of the rest of the planet means it compresses as much as it can as close to the surface as it can get, and then becomes less and less dense as you increase the distance from the center of the Earth.

This is nominally a stable state. Air doesn't move.

When you inject energy into air, that increases the kinetic energy of the air molecules. They bounce off each other and push themselves apart. As a result they have "more space" between them that air molecules than ones that aren't currently heated. What will happen then is the 'less energetic' molecules will 'fill in the spaces' left by the more energetic ones bouncing apart. You might visualize this like sand filling in a hole you are digging by throwing other sand up into the air.

If you do nothing, more energetic molecules end up higher up, and less energetic ones end up lower. Colloquially, "hot air rises". And if you constrain it in an envelope of some form (a balloon for example) then you can create a mass of air that has a lower average density than the air around it and that results in a lifting force.

Here is the rub, as long as you put heat into the air it will stay less dense and your balloon will stay in the air. However, stop adding heat (energy) and the balloon cools and begins to sink. Finally, there is a point where you _cannot_ add any more energy to the air to get it less dense than the air around it. In balloonist terms that is your balloon's ceiling height. 2004 record was 4.1 miles[1]. This is a balloon where you have a super hot flame shooting up into it, and it won't go up any more because you have reached the point where you cannot put enough energy into the air to make it less dense than the surrounding air.

As a result, if you surround a column of air, it might initially rise because energy inside the column is unable to diffuse into the air around the column, but it will only do that until it reaches a new equilibrium point. Early on in the process not being able to spread out allows the air to keep its heat, but at it moves up in the tower/chimney the chimney prevents it from becoming less dense, so relative to the air above it, it gets heavier and heavier per cubic foot. These two effects balance out and the air stops moving.

[1] [https://en.wikipedia.org/wiki/Flight_altitude_record#Hot- air...](https://en.wikipedia.org/wiki/Flight_altitude_record#Hot-air_balloons)

<comment><USER40> I feel like a bunch of people are skirting right around this but this was unclear to me.

The design calls for an absolutely enormous taper at the bottom called the collector. That land area is covered surface, so there is a huge volume of hot air that isn't mixing around the column near the base. I assume this is how they get around the symmetry issues of a uniform cylinder.

I had to go to one of the publications to find a close up photo with much clarity, maybe this will help others to notice.

<comment><USER4> There are sites promoting that idea, but TFA (or the video on the front page, anyway) claims the idea will work without any kind of energy collector at the base.

</comment></comment></comment></comment><comment><USER39> Presumably you just lay a pipe that goes up the side of Everest and free power!

I wonder if the author asked the question "Why don't we have tornadoes all the time?"

If they had, that would have lead them to the physics of tornadoes. In my case it was the physics of so called 'dust devils' in the desert which are much smaller phenomena but based on the same ideas. Warm air rising through cooler air.

You might ask, but why don't we have them all the time? And the answer is that as air goes up, it spreads out, and as it spreads out it becomes less dense, and the lack of density is perceived as a colder 'temperature' even though the air molecules still have more kinetic energy and are thus 'hotter'.

In the video the tube is supposed to constrain the air (which it will) and the warmer air will rise inside of it, but without an energy source the warm air rises until its 'weight' is equivalent to the un-risen air underneath it, at which point it stops rising and the system is stable. If you were to cool off the bottom the air would start sinking again.

This has been experienced time and again by inexperienced makers of fires in their fireplaces. If you don't put enough energy into the air to make it rise, it comes back down the chimney and fills your living space with smoke. A fireplace is a remarkable little machine, where the fire heats the air, which pulls in more air as the air above rises, which puts more oxygen into the fire and increases its energy output etc. But without the fire burning in the fireplace the air stops moving.

Tornadoes benefit from a mass of really cold air sitting on top of warm air. This does two things, one the cold air above pushes down on the warm air to pressurize it, and two when a "hole" begins forming in the cold air mass it operates like an inverted tub drain and the warm air starts draining out of the tub. The energy source for a tornado is the temperature differential that is set up by the result of moisture condensing out of the air and super cooling the air around it.

Similarly a hurricane is powered by the temperature differential between the ocean and the air above it.

All three systems (fireplace, tornado, hurricane) share a common theme, there has to be a source of energy for them to operate. Without it, the air reaches equilibrium and just sits there. No magic allowed.

That said, if instead you built a _tunnel_ , then you could connect two different air masses and extract energy from two different pressure differentials. The most interesting ideas have a tunnel under the Rockies or under the Sierras between the Mojave desert on one side and the milder (and moister) climate on the other. To the delta you can get from that is linear with respect to distance and/or a geographic feature that can inhibit the natural balancing of the air masses (like a range of tall mountains).

Sadly neither super chimneys nor lighter than air vacuum balloons are workable ideas.

Edit: It occurs to me that if you could make the chimney high enough you could put the top in the underside of the jetstream, then you could suck air up using the venturi effect.

<comment><USER33> I think I'm missing something here. How is the temperature differential between a fireplace and the top of that chimney different than the temperature differential between the ground and the top of the super chimney?

<comment><USER16> The air at the top of the chimney is cold because it has expanded due to lower atmospheric pressure. The air inside the chimney undergoes this exact same expansion, and loses the exact same temperature.

A fireplace chimney is different because the air at the bottom _starts out_ hotter than the ambient temperature. When it comes out the top, it has cooled but is still hotter than the ambient temperature at that altitude.

<comment><USER33> I see what you're saying wrt the difference. Thank you.

The air once at the top wouldn't experience any expansion if it was the same density as the outside air, but what about the energy it picks up from expanding? Wouldn't it still have that? Of course it will have lost some from fighting gravity.

<comment><USER16> In a stable atmosphere, all the various effects cancel out.

<comment><USER26> But it's not a stable system, it's being driven with heat from the base.

A simple hydrodynamic [physical] model should be easy to build in the lab.

<comment><USER16> The chimney described here supports itself with the airflow it generates, which means it has to operate 24/7\. That means it has to operate in stable air. It can't.

</comment></comment></comment></comment></comment></comment></comment><comment><USER41> So many signals suggesting this is a wild physics-defying idea that could never work, e.g. how many websites claiming 'this one neat trick solves global warming' really hold the key to solving global warming?

I hope that's not the case and by this time next decade we're all laughing about that century and a half where we put so much carbon in the atmosphere wow wasn't that a hoot...

Realistically, I am sympathetic to the idea that geoengineering, massive structures and engineering projects enabled by modern materials, etc. deserve more thought.

<comment><USER42> Your critique of the proposal is ascientific.

<comment><USER43> And your lack of justification is ascientific.

<comment><USER44> Unfortunately no concrete concern was voiced that could be addressed other than vague comparison to hoax websites.

</comment></comment></comment></comment><comment><USER45> These geoengineering proposals should be understood as mitigation strategies to be implemented _after_ we have reduced carbon emissions, since even then we still have a problem. But this one seems very dubious.

>Speaking in terms of thermodynamic, we can say that chimney prevents adiabatic cooling of a rising parcel of air. Normally, when hot air freely rises in atmosphere, it expands as it gets higher and pushes the surrounding air. That causes surrounding air to heat and rising air to cool. That process continues until equilibrium is reached. At that point air stops its ascending. Unlike freely rising parcel of air, the air in the chimney is restricted in its horizontal expansion and thus, it is not free rising. When air rises in the chimney it also expands but only into upper direction. It compresses the layer of air above it, heats it up and loses its own heat. At the same time air below does the same thing. And that's how it goes all the way until the chimney exit: layers of air are being pushed and push themselves. That results in maintaining the same amount of heat in every layer of air, and that is how the chimney works.

This explanation ignores gravity. Air above you exerts _more pressure_ on you than air below you, albeit by a tiny amount. But when the only thing moving is air in a 5-kilometer chimney, you can't get something for nothing. For intuition, just imagine the chimney is full of water. The water at the bottom is _obviously_ under more pressure than the water at the top. The chimney faces the same consideration, but the ideal gas law applies.

Furthermore, the equation used in the "Calculations" section:

>q = Π dh2 /4 [ (2 g (po - pr) h ) / ( λ (l pr / dh) + ∑ξ pr ) ]½

is sourced from this website:

[http://www.engineeringtoolbox.com/natural-draught- ventilatio...](http://www.engineeringtoolbox.com/natural-draught-ventilation- d_122.html)

which rather obviously works from the assumption that the chimney is placed inside of a _heated_ house.

This all seems to be a sort of Sokal effect in climate science, I'm afraid. The paper 'SubiculumCode cited does not really analyze the thermodynamics used for the chimney and points more to the unrealistic dimensions (1 kilometer _diameter_ and 10 kilometers high).

</comment><comment><USER46> Whatever we do, it's important that we learn how to control the "ingredients" of our atmosphere. There are so many things that could go wrong with our atmosphere and result in mass extinction. Global warming, ice ages, massive volcanic eruptions, etc. If we can find a way to quickly filter out the crap and rebuild our atmosphere... well, this technology could be used for protecting our Earth and future pursuits in space.

</comment><comment><USER47> I think this, however flawed some of the explanation of the effect might be, is something we can try and experiment with fairly easily. Either it can be done, or not. And I believe it can.

Now, we can't let Musk do all the cool things, maybe someone else could step in and fund a project to explore application of updraft towers.

</comment><comment><USER48> We already have something that does the same thing as this claims to (facilitate heat transfer from the surface to the upper atmosphere): it's called the hydrologic cycle.

<comment><USER44> Yes and he goes into that in the video. The argument is that this accelerates that cycle.

<comment><USER48> Ah, ok.

</comment></comment></comment><comment><USER49> Given this, if successful, is creating storms at the top, won't it continually and repeatedly be hit by lightning? And given that it is some kind of fabric, cause havoc?

</comment><comment><USER49> If you search 'solar tower' on youtube, you will see all kinds of videos of existing installations of things that are similar, albeit most are not as tall, nor are they flexible. But the basic concept appears to be the same. Quite a few of them are from many years ago. So it would seem the idea works to some extent, and perhaps the the idea of a much taller, and flexible variant is the crucial difference that will make a big difference.

</comment><comment><USER50> Wouldn't such a chimney take off like a Chinese lantern?

</comment><comment><USER51> Would the radiant heat from the ground be enough to continue this effect at the same rate during the nighttime?

<comment><USER52> This line of inquiry is the key to proving or debunking this. Apparently a few here think that the chimney will fall over when the sun goes down.

This analysis fails to capture the fact that the upper troposphere also cools when the sun goes down - resulting in a maintained differential between the input and the output.

</comment></comment><comment><USER29> Watched the video. Sounds miraculous :) Anyone here knowledgeable of atmospheric thermodynamics?

</comment><comment><USER53> This model must be able to be simulated somehow! To Minecraft!

<comment><USER26> Well we have pipes that go up the side of mountains, open both ends, add a skirt to the bottom, measure if there's a temperature rise at the top?

Then you can start working on viability of materials and such, no?

</comment></comment><comment><USER54> Would it be possible to make these into skyscrapers to house people and businesses? That would handle the financing part of it.

</comment><comment><USER55> Is it really a good idea to move more water vapor, a potent greenhouse gas, significantly higher up in the atmosphere?

<comment><USER38> Doesn't water vapor high in the atmosphere reflect more energy upward than downward? I recall another geo-engineering proposal that involved autonomous ships that would spray water up into the atmosphere to reflect the sun's energy.

<comment><USER55> As far as I know, it gets colder on the ground when there is a clear night.

Presumably the radiation is absorbed by the clouds and the heat stays in the atmosphere.

I have absolutely no idea how it compares to reflective clouds during the day.

</comment></comment></comment><comment><USER10> Hate to be a downer, but out of 157 comments so far, nobody has mentioned ocean acidification. If there was a way to build these chimneys... we could then go on burning fossil fuels & so then the oceans would become more acidic, possibly leading to the inability of krill to form exoskeletons, removing a one of the main oceanic bottom of the food chain food sources.

</comment><comment><USER56> Would this be an efficient source of air pressure for the Hyperloop?

<comment><USER57> Hyperloop needs vacuum, not pressure.

<comment><USER42> Pressure can be efficiently converted to vacuum I believe.

<comment><USER58> I'm not sure why this is being downvoted. The method that immediately comes to mind is using the Venturi effect, though admittedly I don't know the efficiencies involved.

</comment></comment></comment></comment><comment> chroem- Whoever made this assumes that the chimney wall would be a perfect insulator, which absolutely cannot be the case if it's supposed to be a thin cloth or film barrier. The air would cool to the same temperature as the surrounding atmosphere.

This will not work.

<comment><USER59> Chimneys do not require perfect insulators otherwise no chimneys would work. The biggest thing they do is prevent air mixing which in turn prevents a lot of energy exchange. This could work.

<comment> chroem- You realize that other chimneys have an outside energy source and that this essentially amounts to a free energy device, right?

I can scarcely believe that this is an actual level of argument that's occuring on HN.

<comment><USER60> I am not qualified to evaluate the actual possibility of this device, and there are many points that don't seem plausible to me.

However, the author is _not_ arguing free energy. That would be like arguing wind turbines are "free energy". It's very clearly a solar powered device, with solar energy providing the heat that drives the air movement.

<comment><USER61> I'm not qualified either but this is an important point, the energy is definitely _available_ and photoelectric semiconductors are merely one way to harness it.

Regarding the practical issues, what happens at night? Does it collapse under its own weight? How do you get it up in the sky in the first place?

<comment><USER52> The upper troposphere cools as well, resulting in a maintained differential.

</comment></comment></comment></comment></comment></comment><comment><USER62> Things like this are the reason I don't think global warming will ever be a problem. Even if this example turns out to be a pipe dream, we will eventually figure out a way to lower the temperature or remove co2 from the atmosphere.

<comment><USER63> Global warming is _already_ a problem.

</comment></comment><comment><USER33> Any idea how tall one of these would need to be in theory to support itself? I think that would be a cool sight to see and a great way to prove feasibility.

<comment><USER64> its bunk science i have no clue why this got top of hacker news

</comment></comment><comment><USER65> How much will one of these cost?

<comment><USER66> From another page:

PRICE

It is difficult to estimate the price at this point. Materials should be more expensive than those used for hot air balloons, since they have to be multilayered. Even if they are ten times as expensive the price should be under 10/ m2 (see [http://www.alibaba.com/showroom/hot-air-balloon- fabric.html](http://www.alibaba.com/showroom/hot-air-balloon-fabric.html)). To build 20 m diameter chimney would require as much fabric as 300,000 m2 of fabric or $3,000,000. Outside roping, mushroom cap, ground base, labor and machinery to inflate will increase the price. However, I do not see it bringing above $5 million.

Thus, if 25,000 chimneys of such size are enough to stop global warming, the investment will be less than 1,250 billions (annual US budget deficit). Furthermore, as we get more experienced with building super chimneys, we can make them more powerful by making them taller and wider.

The benefits will be millions of acres of arable land in deserts around the world, fresh water, electricity etc. It is quite possible that we can end up making profit on solving Global Warming problem.

Link: [http://www.superchimney.org/build.html](http://www.superchimney.org/build.html)

<comment><USER67> Its 125 billions, not 1250 billions. Also US deficit is around ~500 bil now (way less then 1250b, but more then 125b)

<comment><USER66> Wikipedia[1] reports deficit was ~1,250 bilions in the 2011-12 timeframe, dropping significantly in 2013. Wayback machine[2] seems to indicate the author wrote the page in the 2013 timeframe, so the figures probably need updating.

[1] [https://en.wikipedia.org/wiki/United_States_federal_budget#/...](https://en.wikipedia.org/wiki/United_States_federal_budget#/media/File:U.S._Total_Deficits_vs._National_Debt_Increases_2001-2010.png)

[2] [https://web.archive.org/web/20131210100653/http://superchimn...](https://web.archive.org/web/20131210100653/http://superchimney.org/build.html)

</comment></comment></comment></comment><comment><USER68> Unreadable on mobile

<comment><USER56> This embedded 10-minute Youtube video contains the core ideas: [https://www.youtube.com/watch?v=BfITeN76Thc](https://www.youtube.com/watch?v=BfITeN76Thc)

Notes:

\- Warm air naturally moves up, and cool air naturally moves down. A chimney is like a hot air balloon

\- The taller the chimney, the faster the smoke rises. Exponentially.

\- The temperature drops 10 C every 1000 meters we go up. This is because there is more heat at the ground than in the sky (Transcriber's note: Dense air at the surface can store more heat than thin air near space can.)

\- Consider a 5km chimney - the air at the base will be 50c warmer than at the top. This will cause dramatic airflow, up to 300 mph. While the air inside will be like the air outside, it will be hotter inside, due to the lack of Adiabatic cooling. When air rises, it pushes on the air it's passing, causing it to exchange heat with the air it's passing.

\- By contrast, the chimney compresses air and causes it to gain heat and rush up, cooling the chimney.

\- When warm air exits the top, the hot air causes precipitation in the cool air it's entering. AKA sudden clouds for deserts, or Oasis_aaS.

\- Deserts are ideal, as they allow year-round operation. (Transcriber's note: Does that mean the ground and the upper atmosphere are less than 50C difference in northern areas?)

\- The rains will cause carbon fixing, as more plants consume it and biodegrade into dirt.

\- Global warming isn't caused by the planet receiving more heat, but by the planet storing more heat. (Transcriber's note: As an amateur astronomer, I disagree slightly. Part of the problem is how even our orbit is, which will change over the next 100,000 years.)

\- This is basically a heat pump for the planet, like a reverse hurricane.

\- There's less atmosphere between the upper atmosphere and space, than there is between the surface and space, so more heat will be radiated away by the air in this way. And the thinner atmosphere will reabsorb less of that heat than the denser atmosphere near the surface would.

\- The chimney will be suspended entirely by the buoyancy of the air leaving it - it will have a "mushroom cap" which will direct exiting air downward, to push the chimney upward.

\- They're expecting to use Hot Air Balloon fabric, and that it will be sturdy enough to be 3 miles (5 kilometers, 1640 story building) tall, and withstand winds and other shearing forces.

\- Close the mushroom caps, and use hot air balloons, during initial inflation; then open the mushroom caps once it's fully inflated.

\- 20 meter diameter chimney is estimated to cost ~ $5000.

\- 25k super chimneys needed to completely address global warming, estimated cost $125,000,000.

\- Total global economy estimated at $71,277,000,000,000, so this is a 0.17% global GDP investment opportunity. (Transcriber's note: IANAL nor fiduciary.)

      There's a table included too, it's not easy to reproduce:

      Height m - 2000 - 3000 - 4000 - 5000 - 5000 - 5000 -
      Diameter m - 500 - 500 - 700 - 1000 - 10 - 20 -
      Air Temperature at the base ?C - 30 - 30 - 30 - 30 - 30 - 30 -
      Air Temperature at the upper end ?C - 10 - 0 - -10 - -20 - -20 - -20 -
      Air Speed m/s - 52.7 - 80.4 - 109.2 - 139 - 139 or 500km/h or 300mph - 139 or 500km/h or 300mph -
      Air Flow kg/s - 12,034,838 - 18,379,911 - 48,938,418 - 127,292,000 - 12,729 - 50,916 -
      Producing electric power Mega Watt - 4447 - 15790 - 77542 - 327,786 - 32.8 - 131.1 -
      amount of water condensate/precipitation kg per second - 0 - 73,520 - 327,887 - 929,231 - 93 - 371 -
      CO2 uptake by irrigated desert tons - 0 - 147835 - 946,146 - 1,478,354 - 148 - 592 -
      number of super-chimneys needed to cool the atmosphere - 224 - 99 - 27 - 10 - 100,000 - 25,000

Edits complete.

<comment><USER69> Re:" Dense air at the surface can store more heat than thin air near space can.)"

So, in theory, if we made the Earth's atmosphere less dense, we'd cool the planet. Correct? Any idea how much less dense?

<comment><USER56> It can be a function of either temperature or density - you can make it "cooler" by sucking all of the air out of the room. Because then, there are fewer air molecules, but they each have the same quantity of heat.

</comment></comment></comment></comment><comment><USER70> If a constant air flow is needed to keep the chimney upright, what will happen during the night, when the desert cools down?

<comment><USER71> The video shows the chimneys mostly being built in deserts and their table has an example of 2km tall chimneys working on only a 20 °C difference. If you're building in a place where the winters or nights are particularly cold you should just built higher to exploit the colder temperatures further in the troposphere.

</comment></comment><comment><USER72> A spelling error makes it hard for me to take the proposal seriously.

For something as important as this, the details count. A loose approach to spelling is disturbing.

<comment><USER73> It's clear from reading that English is not the author's first language. This isn't a case of sloppiness.</comment></comment>


Just Launched: Hashgear(Trending hashtags) {apparel + accessories in 60 seconds} - <AUTHOR> https://hashgear.shop <comment><AUTHOR> Just launched my first company -- a technology-based eCommerce company called Hashgear.

Basically, we take every trending hashtag from Twitter and turn it into t shirts, hoodies, hats, phone cases, tank tops, etc -- within 60 seconds of trending.

The idea came from realizing that people are passionate about expressing themselves through hashtags online but there is no real, reliable source of goods IRL that is updated at the speed of the internet. We give people the opportunity to express themselves in real life, start a conversation, and support causes they believe in.

We have a Philanthropy Program to donate proceeds from products related to hashtags that are associated with natural disasters and humanitarian causes.

Check it out! Any comments welcome -- even trash talk about how fast you could build a better version of this. Hit me up at email@example.com with contact info if you'd like a special HN discount code.

Cheers, Marc</comment>


Show HN: The ultimate full stack starter kit PH launch - <AUTHOR> https://www.producthunt.com/posts/the-ultimate-full-stack-starter-kit <comment><USER2> Not sure I understand - are you showing HN not your project, but its launch announcement on some other site?

</comment><comment><USER3> Not sure how it is the ultimate, I would expect the ultimate to be open and free.

Try [https://apollokit.org](https://apollokit.org) instead</comment>


Evolution of Corporate Logos - <AUTHOR> http://artatm.com/2010/04/evolution-of-logos-of-famous-brands/

<comment><USER2> I found it interesting how some companies iterated & evolve their logo many, many times - while others made only a few changes over the years (e.g. Burger King, Playboy & FedEx). The latter, it seems, are great examples of the value of truly talented graphic designers.</comment>


Netochka Nezvanova - <AUTHOR> http://www.usemod.com/cgi-bin/mb.pl?NetochkaNezvanova

<comment><AUTHOR> See also <http://en.wikipedia.org/wiki/Netochka_Nezvanova> .

Why I post that now? In some ways this story resembles, even if in other ways it is the opposite of, what I read here about why.

<comment><USER2> It seems 'hacker' must be redefined.

Until now it was about programmers and coders -- technical people with focused mind living inside a digital world.

Now more open minded (not just digital thinking) and more free people (with the spirit of an artist) like _why, NN, Hasan Elahi -- are taking over the web.

The next web superstars won't be NASA crackers, Facebook founders, rockstar programmers, alpha geeks. We will sink back to build infrastructures on which new breed heroes will bring and open the web forward.

</comment></comment><comment><USER3> I was just thinking of Netochka, yesterday, as everyone was talking about how the internet persona and alias _why was an artwork in itself. Despite all of _why's accomplishments and contributions, which are more and greater than Netochka, Netochka will go down as a much greater artist and phenomenom.

<comment><USER4> Netochka was not only more dramatic, but thematic. As the original article says, she helped reinforced the cyberspace mythology her audience was interested in. _why reinforced hacker mythology mind you, but cyberspace culture is much bigger.

<comment><USER3> Yeah, you're right, I shouldn't have said that _why contributed more, just that _why's contributions reached wider audiences, at least in a direct way.

It's nice to see that there are some art hackers, or informed members, on hacker news, though!

<comment><USER4> I recommend you swing by MeatballWiki (<http://www.usemod.com/cgi-bin/mb.pl>). Nine and a half years ongoing, that's where I express my artistic side, including the article linked above coincidentally.

Here I'm mostly representing my day job.

</comment></comment></comment></comment><comment><USER5> _"The epoch of the generalist has arrived -- again. Any fool can program and most do. Software engineers are emotionally inept. In today's unstable + dynamic environment they do not stand a chance."_ \- Netochka Nezvanova

[http://dir.salon.com/story/tech/feature/2002/03/01/netochka/...](http://dir.salon.com/story/tech/feature/2002/03/01/netochka/index3.html)</comment>


Snowden maintains NSA has access to company servers, so someone's lying - <AUTHOR> http://gigaom.com/2013/07/09/snowden-maintains-the-nsa-has-direct-access-to-company-servers-which-means-someone-is-lying/

<comment><USER2> How is Snowden possibly lying? He's reading verbatim from the NSA documents which use the words "direct access". Also he isn't "maintaining" this, this is part of his original interview from over a month ago.

<comment><USER3> Which ones? The PRISM slides said "collection directly from the servers of..." which is not the same as 'direct access'. Are there different NSA documents, if so it would be useful to see the context of the wording in that case.

<comment><USER2> Your quote is accurate, "direct access" is not verbatim. Though "collection directly" and "direct access" seem semantically the same to me in the context of the slide. [1]

The relevant slide is talking about two types of mechanisms the NSA analyst should use. The "Upstream" and "PRISM". It's within the the Prism description that the words "collection directly from the servers of.." is used. So it's not referring to raw data collection through neutral access points, as that's what the "Upstream" is. It's explicitly saying the NSA has direct access to these companies.

[1] [http://i.imgur.com/kIEtXjk.jpg](http://i.imgur.com/kIEtXjk.jpg)

<comment><USER3> > It's explicitly saying the NSA has direct access to these companies

It's explicitly saying that the NSA has access to data that would come directly from the relevant company servers, as opposed to having to intercept that data during transmission across the network. (Edit: an intercept is what 'upstream' collection would imply)

The companies themselves are still the ones who end up providing the data to NSA though, just like the fact that my browser obtained your comment "directly from the servers of Hacker News" does not imply that I have direct access to the server hardware underlying HN.

<comment><USER2> > The companies themselves are still the ones who end up providing the data to > NSA though

Well that's certainly what the companies are saying. Whether they are telling truth (personally I think they are) or not is something else. Snowden is definitely not the one lying about this, since at worst his interpretation was very sensible, and at best it is the very interpretation intended by the author.

<comment><USER3> > Snowden is definitely not the one lying about this, since at worst his > interpretation was very sensible, and at best it is the very interpretation > intended by the author.

"His interpretation"?

Snowden is the one who actually _has_ experience within the Intelligence Community. I managed to figure out what it meant with a little background in computer and networks knowledge and no background with IC work. Snowden has superior qualifications in both, and you're saying that Snowden might have made an honest mistake?

He knew what NSA jargon meant; he knew what the slide meant. The only thing you can say for him 'at best' is that he allowed journalists to come to a sensible conclusion based on what _they_ knew, but that is still manipulative.

And in the actual event he even claimed that they could see the very thoughts form in your head, which is something beyond even mere manipulation.

<comment><USER2> > I managed to figure out what it meant with a little background in computer > and networks knowledge and no background with IC work.

We still don't know what exactly is going on, or know if direct access really exists, so this is premature.

Secondly, your earlier example of using your web browser to collect directly has nothing to do with the actual slides, which talk about getting special access from the companies, and the document includes a timeline indicating when each company finally signed on to the Prism program.

He said "direct access" and the document says "collection directly from the servers of..".

> He knew what NSA jargon meant; he knew what the slide meant.

The NSA is a huge organization with a budget of tens of billions of dollars and employs tens of thousands of people. Snowden of course does not have complete understanding of everything, nor does Keith Alexander, nor does James Clapper, the DNI who blatantly lied to congress about collecting data on millions of Americans.

Placing any kind of blame on Snowden for directly paraphrasing a NSA document makes absolutely no sense.

Edit: 'paraphase' is far too kind. It's nearly the exact words, with the addition of 'access'. That NSA has special non-public access is something even the companies admit.

</comment></comment></comment></comment></comment></comment></comment><comment><USER4> Is it possible the NSA compromised Google, Facebook, etc. servers without the companies knowing?

</comment><comment><USER5> These publicly traded companies lying? There's plenty of things that companies are legally obligated to lie about. See Boeing, Raytheon etc.... The fact that it is now a tech company is just new players in the game.

The problem with his claims is that he has made far-reaching accusations such as "I could wiretap the president's email" with no proof. While I wouldn't necessarily be surprised if he could (see the existence of Carnivore), to make that level of a claim without SHOWING and VERIFYING that claim in the same video is frightnigly foolish in my opinion. I'm guessing that it would have to be access to servers since other 'communications' require the actual application. In other words, there would almost need to be application level awareness of this external output point. Again, not impossible but could / should have been presented better.

</comment><comment><USER6> There's a difference between lying and carefully choosing your words.

<comment><USER7> Really?

<comment><USER8> Yes.</comment></comment></comment>


Glot.io: Open Source pastebin with runnable snippets and API - <AUTHOR> https://glot.io/ <comment><USER2> This is really cool to see, but also somewhat depressing because it reminds me that I spent about 500 hours of my free time building the same thing, and even had it deployed at codetrain.io for a while, but then lost interest and now my code's wasting away in a private bitbucket repo.

Before I shut mine down it could run 13 or so different languages, spin up collaborative REPLs for Node.js/Python/Ruby, and organize snippets into tutorials/lessions, etc. It was awesome, but now sits in my side project graveyard. It's a shame really.

Glad to see glot.io getting more attention.

<comment><USER3> you should open source it

</comment></comment><comment><USER4> This is very cool. I'd really love to see a "how it works" blog post, particularly for the runnable snippets, and what your approach to protecting it from abuse and hacking is.

<comment><USER5> It's opensource. [https://github.com/prasmussen/glot](https://github.com/prasmussen/glot)

<comment><USER4> The code is, but I assume there's some configuration that's not code that might be interesting in the "avoid abuse and hacking" space.

<comment><USER6> _All_ of the code is open source. This is a beautiful thing:

website: [https://github.com/prasmussen/glot- www](https://github.com/prasmussen/glot-www)

snippets: [https://github.com/prasmussen/glot- snippets](https://github.com/prasmussen/glot-snippets)

runner-web: [https://github.com/prasmussen/glot- run](https://github.com/prasmussen/glot-run)

runner-onserver: [https://github.com/prasmussen/glot-code- runner](https://github.com/prasmussen/glot-code-runner)

containers: [https://github.com/prasmussen/glot- containers](https://github.com/prasmussen/glot-containers)

EDIT: And this is directly from the main github source repository -- [https://github.com/prasmussen/glot](https://github.com/prasmussen/glot)

<comment><USER7> Is there a guide for setting this up internally (within a local network)?

</comment></comment></comment></comment></comment><comment><USER8> I couldn't help but notice they use Haskell and Yesod for the web portion [https://github.com/prasmussen/glot-www](https://github.com/prasmussen/glot- www)

</comment><comment><USER9> Great, would be nice to have and updated clang (seems to be using 3.5.1) and python3 (using 3.4.3). Generally its nice to point out the version of the compiler it's using somewhere as a note.

</comment><comment><USER10> Hopefully you are ready for [https://conference.hitb.org/hitbsecconf2016ams/sessions/esca...](https://conference.hitb.org/hitbsecconf2016ams/sessions/escape- from-the-docker-kvm-qemu-machine/)

<comment> alch- This. Awesome service, but pleasefortheloveofgod don't let people run arbitrary code inside Docker, unless you don't mind them getting out into the parent OS and messing around. You want VMs for that. (Yeah, that's much more resource intensive. Safely running arbitrary code is hard.)

<comment><USER11> seccomp provides a really good jail, probably all that's needed here.

</comment></comment></comment><comment><USER12> This looks like a very interesting project, but I think choices made for data storage (PostgreSQL + CouchDB) is quite odd.

To me the obvious choice for this would be to use a DVCS repo for each "glot", and create files inside it, just like Gist does. I personally would prefer this be mercurial repos' but I'd probably just make it support git too.

I'd probably also use libvirt rather than Docker specifically, to allow for more flexible setups.

</comment><comment><USER13> This is like IdeOne [1]. But, this is very cool because open source. IdeOne is not open source project.

[1]: [http://www.ideone.com](http://www.ideone.com)

</comment><comment><USER14> There's also [http://www.gistrun.com](http://www.gistrun.com) , which executes all code on the client.

</comment><comment><USER15> FYI - This is the work of one guy only not multiple, just thought i mention it as people refer to the dev in plural.

And my guess as to different parts of the application has been developed in different languages and to the use of two db's are for educational purposes.

<comment><USER16> Could also be singular 'they' \-- that's how I read it.

</comment></comment><comment><USER17> There are a lot more problems than you think with letting users have arbitrary code execution. And no, Docker is not an acceptable security solution for this, since it's most certainly possible to break out of containers. Even if you're using a dedicated VM, this is not a good idea. And from a brief look at glot-code-runner, it doesn't seem like there's even that much built in to protect against various forms of use.

A more sane design would be to use something like emscripten to enable all these different languages to run in the browser.

<comment><USER18> "Docker is not an acceptable security solution for this, since it's most certainly possible to break out of containers."

Could you point to some resources that show that it is possible to break out of Docker containers? I understand that there have been bugs in the past that have caused this (using that to conclude that glot.io shouldn't use Docker is a bit like saying OpenSSL is now useless because of heartbleed) but it seems unlikely that breaking out of containers is possible due to the way Docker is designed.

<comment><USER19> [http://www.cvedetails.com/product/28125/Docker- Docker.html?v...](http://www.cvedetails.com/product/28125/Docker- Docker.html?vendor_id=13534)

[https://github.com/docker/docker/issues/12317](https://github.com/docker/docker/issues/12317) [https://github.com/gabrtv/shocker](https://github.com/gabrtv/shocker)

[https://www.oreilly.com/ideas/docker- security](https://www.oreilly.com/ideas/docker-security)

I'm sure there will be more

Edit: yup, as cited below: [https://conference.hitb.org/hitbsecconf2016ams/sessions/esca...](https://conference.hitb.org/hitbsecconf2016ams/sessions/escape- from-the-docker-kvm-qemu-machine/)

<comment><USER20> Most of the vulnerabilities you mention are actually kernel vulnerabilities. While they affect Docker, they more accurately affect everything that uses "Linux containers". Although, Docker did have a bad history of security bugs with symlinks.

But given the fact that Linux doesn't have real containers, I feel very conflicted about opening that up to the internet.

</comment></comment></comment></comment><comment><USER21> This is incredible. The key is in its simplicity, speed, and variety of languages.

Kudos!

</comment><comment><USER6> Some metadata:

MIT license

Haskell infrastructure

Containered

Open source everything -- runners, site, etc

Very nice!

<comment><USER22> It looks like only glot-www is Haskell.

glot-snippets and glot-run are both erlang APIs, and glot-code-runner is a go application.

</comment></comment><comment><USER23> Please make R a language here. That would be amazing to be able to run snippets. I could see a lot of uses!

<comment><USER24> +1 for R. I was pleasantly surprised to see Julia there

</comment></comment><comment><USER25> Thank you for this! Going to share it with the rest of my team right now. I always need a tool like this and had been using [http://codepad.org/](http://codepad.org/) until now. This interface is much slicker.

</comment><comment><USER26> This is very fascinating.

How does the rocket science work here? Like how do you run different programming languages in the client side.

Do they pass the code to the server and run it in there then pass it to the client?

<comment><USER27> Yeah, if you check the repo it's running the code in a specialized docker container with no network access.

<comment><USER26> Thanks I see it: [https://github.com/prasmussen/glot- containers](https://github.com/prasmussen/glot-containers)

Guess I better start learning about docker/containers soon

</comment></comment></comment><comment><USER28> This is excellent! Reminds me of a tool I wrote a few years back that only supported 4 languages that we used at my past company. Great to see this open sourced!

</comment><comment><USER29> Check another similar tool BitRun - [https://bit.run/](https://bit.run/) Very good for rapid prototyping.

</comment><comment><USER30> I am interested to know what other ways of allowing untrusted user code execution securely. How does one enforce resource quotas (timeouts, etc)?

<comment><USER30> In particular, anything that can run on the JVM? I know Lua is reall great for this type of stuff, but it's JVM support is abysmal.

</comment></comment><comment><USER31> I think this is pretty cool. Might be nice to be able to embed them (i.e. like you can with Github gists).

</comment><comment><USER32> The idea of using docker excellent.

</comment><comment><USER33> nice, you can even require other files in JS - although it would be nice to be able to customize the file names - but still very useful for the kind of thing I would normally use a gist for.

Edit: I do wish it had a more recent version of node though (currently v0.12.7)

</comment><comment><USER34> This is good! Though, some sort of captcha will be useful to avoid people spamming this.

</comment><comment><USER35> Feature request - be able to make the editor's height taller.

Other than that, awesome job!

<comment><USER19> Would be cool to integrate with [https://ace.c9.io/#nav=about](https://ace.c9.io/#nav=about)

<comment><USER36> It is using Ace as the code editor: [https://glot.io/about](https://glot.io/about)

> Ace is used as the code editor. Make sure to check out the leftmost and > rightmost tabs, where you can select language version, set a custom run > command and change the editor keybindings.

</comment></comment></comment><comment><USER37> This is interesting, but I'm not sure why they use CouchDB and PostgreSQL.

<comment><USER31> Can you elaborate?

<comment><USER38> Probably refering to the diagram from their github page[1]

[1] [https://github.com/prasmussen/glot](https://github.com/prasmussen/glot)

Pet Peeve: There is no way to post ASCII diagrams on HN

<comment><USER39>
          snippets.glot.io                  glot.io                     run.glot.io
        ┌──────────────────┐   http   ┌──────────────────┐   http   ┌──────────────────┐
        │  glot-snippets   │◀─────────│     glot-www     │─────────▶│     glot-run     │
        └──────────────────┘          └──────────────────┘          └──────────────────┘
                  │                             │                             │
             http │                             │                        http │
                  ▼                             ▼                             ▼
        ┌──────────────────┐          ┌──────────────────┐          ┌ ─ ─ ─ ─ ─ ─ ─ ─ ─
        │     couchdb      │          │    postgresql    │                 docker      │
        └──────────────────┘          └──────────────────┘          └ ─ ─ ─ ─ ─ ─ ─ ─ ─

Almost works. I just pasted it as code.

<comment><USER40> I'd say it works quite well. That looks perfect.

</comment></comment></comment></comment></comment><comment><USER41> Can I install packages/modules for my scripts (e.g. using _npm_ )?

<comment><USER42> Doesn't look like it. The containers don't have network access, either so putting something like `npm install left-pad && node main.js` as the run command won't work.

</comment></comment><comment><USER43> I hope they add R soon.

<comment><USER44> I wrote up the Perl 6 entry. It's relatively trivial to add languages to the project you just need to have a link to a docker registry with the version of R you want. The rest is basically just bits of boiler plate in the other repositories for the project.

</comment></comment><comment><USER45> This is awesome. I wonder how you make it secure. Btw, I am the dev behind [https://codepad.remoteinterview.io](https://codepad.remoteinterview.io)

</comment><comment><USER46> Nice work on this!</comment>


Ask HN: What are your working tunes? - <AUTHOR>

I really get things done with the Album Leaf's Enchanted Hill album. Unfortunately, the album eventually ends. Looking to add to the arsenal, so I want to know: what are some artists or albums that seem to put you in the zone? <comment><USER2> "The Sims 3 Pets" soundtrack. No joke. I've never played The Sims 3, but like the soundtrack because it is like [good] elevator music. Kind of reminds me of the SimCity 2000 soundtrack, just happy but with that undertone of momentum.

Game and movie soundtracks are great for work. Particularly when they are just scores or choirs (as opposed to bands, duets, or single vocalists). Way less distracting.

<comment><AUTHOR> "that undertone of momentum". Yes.

</comment></comment><comment><USER3> Limbik Frequencies [http://tunein.com/radio/Limbik- Frequencies-s2225/](http://tunein.com/radio/Limbik-Frequencies-s2225/)

I've made a spotify playlist that tries to mirror it. It's not as good as the real thing but it's a start:

[http://open.spotify.com/user/rickrrr/playlist/2ajgobJG1lMT1I...](http://open.spotify.com/user/rickrrr/playlist/2ajgobJG1lMT1IKAm8AR96)

<comment><AUTHOR> Cool. Following.

</comment></comment><comment><USER4> You might want to try the FTL soundtrack at [http://benprunty.bandcamp.com/album/ftl](http://benprunty.bandcamp.com/album/ftl). I listen to a lot of video game soundtracks, recently Chrono Trigger, Chrono Cross, FTL, a few from Portal and Portal 2. Sometimes Chipzel ([http://chipzel.co.uk](http://chipzel.co.uk)).

</comment><comment><USER5> Ozric Tentacles. Perfect psychedelic space rock jams with no lyrics.

From Wikipedia: Ozric music is a highly psychedelic mixture of driving basslines, keyboard and intricate guitar work, with a sound influenced by Steve Hillage and Gong. Many of the Ozrics' songs are in unusual time signatures and/or unusual Eastern-influenced modes. Furthermore, the band often features complex arrangements, which change time signature, key signature and tempo frequently in the course of a track, a well-known element present in progressive rock. There are also moments of straightforward funk- influenced grooves and strong influences from jazz fusion, dub/reggae and ambient music styles.

These features are mixed with electronic elements, including densely layered psytrance- and techno-influenced arpeggiated synthesizers, pads, synth basslines, effects and programmed drumbeats. There is also a strong influence from dub and ambient music, with many quiet relaxed tracks, that balance the frenetic, intense material.

</comment><comment><USER6> Interesting topic. For working, I prefer calm music myself, like a few others in this thread, though I like other more active or vigorous kinds too, when not working.

I've thought about this myself and tried to find music to listen to while programming or writing. Haven't found too much that I like, somehow. Will check out the links in this thread.

Here is one that I do like - blogged about it here, with a link and embed to the music, and someone I know also said they liked it for working - a sitar performance by Vilayat Khan (Rarely Heard Ragas), who was of the calibre of Ravi Shankar:

[http://jugad2.blogspot.in/2013/10/music-video-sitar- vilayat-...](http://jugad2.blogspot.in/2013/10/music-video-sitar-vilayat-khan- rarely.html)

</comment><comment><USER7> Ambient seems to work best for me. More generally speaking, calm, instrumental music (i.e. no vocals), which includes some jazz-y music as well (In A Silent Way by Miles Davis, or Sunset Mission by Bohren & Der Club of Gore, to name two).

If that is up your alley, I can recommend the following artists:

Boards of Canada come to mind. Carbon Based Lifeforms (especially their album "Twenty Three"). Marconi Union. Steve Roach made some pretty awesome stuff (Structures From Silence especially).

Every now and then - rarely, actually, but that is not a statement - I will get out the Cocteau Twins. There are lots of vocals, of course, but rarely anything resembling lyrics, so that works for me.

Also, some of the stuff Dead Can Dance made before they split up was pretty great. Towards the Within and Spiritchaser were quite great.

</comment><comment><USER8> [http://musicforprogramming.net/](http://musicforprogramming.net/)

</comment><comment><USER9> David Tipper's Forward Escape is some of the best music I've heard in the last 10 years, and doubles as great programming music too: [http://open.spotify.com/album/6iXjPAUqAY5c3cVe1lNHut](http://open.spotify.com/album/6iXjPAUqAY5c3cVe1lNHut)

The Crypt of the Necrodancer soundtrack is really great: [https://www.youtube.com/watch?v=UrS1RyuoG0I](https://www.youtube.com/watch?v=UrS1RyuoG0I)

Instrumental prog is pretty good: Liquid Tension Experiment, Joe Satriani, Scale the Summit...

<comment><USER10> Thanks for the suggestions! Great background music.

</comment></comment><comment><USER11> Following a LPT from /r/programming, I'm trying video game soundtracks, which are supposedly designed to help you concentrate on the task at hand, whether that's grinding or a boss fight. No guarantee that you'll get the boss fight song when you're in the middle of something difficult, though, so YMMV.

Currently using: [https://itunes.apple.com/us/album/borderlands-2-original- sou...](https://itunes.apple.com/us/album/borderlands-2-original- soundtrack/id557018768)

</comment><comment><USER12> Chiptunes are great for programming. Check out fantomenk.

[https://soundcloud.com/fantomenk/cpu- mood-2010](https://soundcloud.com/fantomenk/cpu-mood-2010)

[https://soundcloud.com/fantomenk/dischipo-2009](https://soundcloud.com/fantomenk/dischipo-2009)

[https://soundcloud.com/fantomenk/fantomenk-playing-with- powe...](https://soundcloud.com/fantomenk/fantomenk-playing-with-power)

<comment><USER13> I like WMD on bandcamp: [https://wmdchiptune.bandcamp.com/album/this-was-the- end](https://wmdchiptune.bandcamp.com/album/this-was-the-end)

I also really liked this set, but some people may find it a bit much: [https://chibitech.bandcamp.com/album/chibi-tech-live-blip- fe...](https://chibitech.bandcamp.com/album/chibi-tech-live-blip-festival- tokyo-2012)

</comment></comment><comment><USER14> I don't think it's available yet, but I'm curious about Carl Franklin's project "Music To Code By". He's specifically trying to craft an album that's "designed to induce a state of flow suitable for writing code."

[https://www.kickstarter.com/projects/311638984/music-to- code...](https://www.kickstarter.com/projects/311638984/music-to-code-by)

<comment><USER6> That's a pretty cool idea. Will check it out, thanks.

</comment></comment><comment><USER15> I don't have the patience to discover and curate a lot of music myself these days (atleast not enough to last my work day), so I like a couple of online radio stations. This one is my favorite:

WritheM Radio's Programming Electronic and Alternative on Grooveshark: [http://grooveshark.com/#!/writhem/broadcast](http://grooveshark.com/#!/writhem/broadcast)

</comment><comment><USER16> [http://di.fm](http://di.fm) has a wide variety of electronica that appeals to my various moods... most frequently Liquid DnB or Chillstep these days, but Chillout Dreams and Vocal Trance are also favorites. I'm usually on there unless I wanted to listen to a specific artist on Google Play All Access.

<comment><USER7> I used to listen to di.fm a lot a couple of years back. I stopped listening when I got myself a new desktop computer at the beginning of 2009, and made the mistake of buying an Asus EeeBox. For some reason, Shoutcast streams in general would run very badly on that machine, so I stopped. :-/

Thanks for the hint, I will see how that goes. :)

</comment></comment><comment><USER17> Video game music & rearrangements, especially from [http://ocremix.org](http://ocremix.org), but most typically metal, especially of the power & progressive variety. I like to constantly engage my brain, especially with overtones of overcoming adversity, so power metal is perfect for that.

<comment><USER7> While I personally prefer electronic music, I was kind of surprised that most of the programmers I've met in person seemed to be into metal, covering pretty much everything from good old Black Sabbath through Power Metal all the way to Grindcore and Black Metal.

Not that I am judging in any way. I used to listen to a lot of Heavy Metal, and I still do occasionally (especially when I am angry/frustrated - it seems to have a cathartic effect on me).

For programming, I prefer calm, quiet, unobtrusive music, but apparently there are many programmers out there who like to rock. :)

</comment></comment><comment><USER18> Depends on the task and my mood. Classical and prog-rock are the most common for me. Lately, I've found myself not having any music most of the time—I'm better able to concentrate without it. I think that's partially because I am a musician, and I find myself analyzing it (regardless of whether it has words).

</comment><comment><USER19> Pink Floyd, M83, Porcupine Tree, Dead Skeletons Dead Mantra, Arcade Fire, Naked and Famous. Some of it is very spacey, some of it I have listened to so many times I don't pay attention to it any more. If you still like the above bands but are tired of the albums, move on to bootleg concerts.

</comment><comment><USER20> Not an artist or album specifically, but Soma.FM is my go-to for work noise. Instrumental electronica, ambient, or you get it it with lyrics if you like. One of my faves is ambient with SF public safety radio (police, fire) dubbed on top. Sounds weird, but works well for technical work.

</comment><comment><USER21> I tend to gravitate to music without lyrics.

I've been listening to a playlist I found on Spotify - "Beats to think to"

Also, if you like the sounds of a coffee shop, checkout coffitivity.com (no affiliation). If I'm in the right mood, gets me in the zone.

<comment><USER22> I think no lyrics is key! Instrumental tracks are less intrusive and have a lot of repeating patterns.

<comment><USER7> I completely agree!

I think it is the acoustic equivalent to the Clippy effect: Human voices tend to take up a substantial portion of our mental bandwidth, because it is not just a sound our brain has to recognize, but then it has to go and actually _understand_ the words being said or sung.

Instrumental music tends to have - at least on me - the opposite effect, it occupies the parts of my mind that otherwise might distract me, leaving the parts doing the hard work alone.

</comment></comment></comment><comment><USER23> [http://8tracks.com/yellowcake/](http://8tracks.com/yellowcake/)

8tracks has a lot of great playlists. The key is finding a user who makes good ones. This yellowcake guy has over a hundred, of which almost all are great.

</comment><comment><USER24> Mostly the Trance channels on DI.FM .. Vocal Trance, Epic Trance, Classic Trance, etc.

I find Trance has enough energy/momentum to motivate me, without being distracting like most of the rock/metal/otherstuff I listen to other times.

</comment><comment><USER10> Overwerk, Orbital, and similar electronic/ambient artists are my zen-mode gotos. 9:00am after writing code until 4:00am? It better have screeching electric guitar and heavy bass. Industrial is a great way to wake up.

</comment><comment><USER10> For the mid-afternoon slump, I dig Dave Snelgrove's bass tracks: [https://soundcloud.com/davidsnelgrove](https://soundcloud.com/davidsnelgrove)

</comment><comment><USER25> My Pandora channels on shuffle - largely: drum-n-bass, ska, and punk. For me, Pandora requires the least cognitive load. If I start finding it distracting - rather than beneficial - I hit pause.

<comment><AUTHOR> The ads...

</comment></comment><comment><USER26> white/brown noise- ocean waves, rainfall, etc.

A couple links that have crossed the HN Radar before:

[http://mynoise.net/NoiseMachines/waterfallNoiseGenerator.php](http://mynoise.net/NoiseMachines/waterfallNoiseGenerator.php)

[http://asoftmurmur.com/](http://asoftmurmur.com/)

[http://musicforprogramming.net/](http://musicforprogramming.net/)

<comment><USER7> I knew musicforprogramming, but the first two links are awesome, too. Thank you very much!

</comment></comment><comment><USER27> I think [https://bop.fm](https://bop.fm) has good potential for creating playlists since it uses multiple services you can find most songs.

</comment><comment><USER28> I like more instrumental post-rock stuff like Godspeed You! Black Emperor or Explosions in the Sky, as well as some more electronic stuff like Vondelpark or CFCF.

</comment><comment><AUTHOR> From the suggestions I've checked out soma.fm has been my favorite. DEF CON station is doing me right

</comment><comment><USER29> pick a song and loop it. loop it for 5-6 hours. it's something that will get into your skin but then fade off and become a nice sofa to sit on (per say). After an hour any song on loop will just become working background.

</comment><comment><USER30> The Aquabats "Charge!!" 24/7

</comment><comment><USER31> The "Deep Focus" playlist on Spotify

</comment><comment><USER32> Lately M83 Pandora station

</comment><comment><USER33> Soma.fm

<comment><AUTHOR> !</comment></comment>


Ask HN: Is PCI compliance something that every web developer should know? - <AUTHOR> <comment><USER3> If the developer writes code that handles credit card information, absolutely. Most organizations utilize third parties to handle credit card info so they don't have to be PCI compliant. Even then, it helps to know something about PCI because the developer may be storing more information than needed.

In general I think every developer should receive secure coding training. Most developers don't...

<comment><USER4> Depends on how you write the code

(generally - theres a lot of coding specifics involved) Authorize.net via their API absolutely requires PCI compliance and an SSL certificate on your site. Stripe recommends an SSL certificate with their basic JS code. And unless your sending a user directly to Paypal's website to login via Paypal, if you use their API, you should have an SSL certificate and be PCI compliant.

IE: if the CC info is entered on a page you built, on your server, yes - <USER2> and PCI. If your sending the user to another site (ie: Paypal or using Stripes JS code) - no, it's on them.

Most programmers should at least read the parts of OWASP that pertain to their language ([https://www.owasp.org](https://www.owasp.org)). If it gets entered into a form and stored in some sort of DB, you should at least code with basic precautions.

</comment></comment><comment><USER5> If you develop a site that takes payment via credit card, even when processed by a third party processor, it's pretty irresponsible not to be familiar with it. Even if you're only attesting to being a SAQ A merchant, you'll want to know why. There's not that much too it, and it's really the minimum you should be thinking about.

That said, we'd all live in a better world of every web developer knew the OWASP recommendations inside and out. I can dream.</comment>


How I Failed to Build a Million Dollar App - <AUTHOR> http://appmakerhub.com/how-i-failed-build-million-dollar-app

<comment><USER2> "(Shameless plug: you can try treehouse for free right here. If you choose to become a paying member, I do receive a small commission..."

Linked page sez: Get 3 Months Off Our Basic Annual Plan ($75 Value) For A Limited Time!

Three months _off_ an annual plan? So, I pay for a year and get only 9 months? Please tell me that's not what they mean.

<comment><USER3> That's not what they mean.</comment></comment>


Tools for Radicals - <AUTHOR> https://hackernoon.com/tools-for-radicals-73b7cbbfc276 <comment><USER2> For those wondering, like me:

With "radicals" they mean normal software development, but with "radical simplicity".

However, this doesn't sound very radical to me. There are lots of simplification movements, and have ever been, in software development. Moreover, server-side static pages are already a modern trend, too.</comment>


How we almost didn't raise $800K in the worst investment market in years - <AUTHOR> http://blog.uservoice.com/entries/how-we-almost-didnt-raise-800k-in-the-worst-investment-market-in-years

<comment><USER2> I'm curious to hear more details about your "tipping point". What sort of metrics seem to put investors at ease? Was it a specific revenue goal, a more polished plan of action, a certain user-growth model, or all of the above? My limited experience from working at a consumer internet startup has taught me that once you hit about a million users, everything else seems to fall into place a lot easier. Of course that varies widely depending on the business, so I'm just interested in hearing other data points.

<comment><AUTHOR> Our key metrics really didn't change over the course of the fundraising process. We had be live for over a year and sign up growth as pretty stable. The only "metric" that changed was the current revenue/mo numbers. But it really wasn't a change in metrics that changed our fortunes. It was really just social proof and finding the right story that resonated.

</comment></comment><comment><USER3> Thanks for sharing your behind the scene story. Having "social proof" from early investors and managing "a herding situation" to enable others chipping in seem to be critical components during a fund raising process.

As a B2B Saas provider, do you feel that enterprises are open to pay monthly subscription fee via credit cards? We are dealing B2B business, mostly w/banks & pharms. Managing invoices are challenging, and everyone is trying to drag on their feet when paying invoices. Monthly subscription fee would be much easier to manage. Thanks for your insight in advance.

<comment><USER4> Consider only offering enterprises a yearly pre-pay option if they want invoicing. That reduces your paperwork and lets you put the cash to work. Once you're only dealing with yearly invoices, the collections challenge is simpler.

If the product is SaaS you have the ultimate power to resolve non-payment: stop service.

Just send a polite note to their accounts payable team or whomever is your main contact say "We really love you as a customer, but our invoice is overdue and forcing an automatic stop of service on XXX, XXXX (30 days from today). We really don't wish to loose your firm as a customer. Please contact us as soon as possible so we can avoid a service interruption" Make sure the subject says something like "30 days notice: Automatic Stop of Service on XXXX for non- payment" They should jump to action. If not, remind them again in 2 weeks, then if no action stop the service.

If your service is important to them, you'll be impressed at how quickly things get paid.

<comment><USER3> @wavesplash. Thanks for your insights. We incorporated your suggestions into our sales & invoicing processes. Happy Spring!

</comment></comment></comment><comment><AUTHOR> Happy to answer any questions about this that people may have.

<comment><USER5> This is very informative, kudos to you guys for sharing. How did you guys set your goals as far as how much to raise and the amount of equity you were willing to give up? What did having the extra investment mean for you guys starting out?

<comment><AUTHOR> Honestly the determiniation of how much to raise was pretty back of the envelope. I think originally we thought about doing $250K but then after talking to other people it seemed that's a pretty naive number. You really can't get much done for $250K and plus if any investors are interested they'll bring in your friends and you'll end up raising $600-800 anyways (this happened to the Weeblies if I recall).

I won't get into valuation or equity given up but I always say that difference between $0 in the bank (or whatever you can relunctantly squeeze out of family members) and ~$1M is a tangible difference in your ability to survive and succeed. It's like you hear about YC and their equity cut. If what you give up is easily surpassed by the speed at which you can now move then it's worth it. If you can't take a million dollars (when you have 0) and improve your outcome by more than your dilution then you shouldn't take the money.

<comment><USER6> In the article you say, "...we also took the initiative to set our own valuation. Investors were very value-conscious in those days. It's not just enough to be a solid opportunity, you also need to be a good value. We set a price we thought was fair and wouldn't generate a lot of push back."

Don't need to disclose the actual number but how did you determine what was a "fair" valuation. Was it a discount to prevailing valuations? Did all investors buy in at the same valuation or were the terms more generous for the first investors?

<comment><AUTHOR> We just sat down and picked an amount of valuation (or really dilution) that we were comfortable with and went with it. Everyone was at the same valuation. There was no discount for first movers.

</comment></comment></comment></comment></comment><comment><USER7> I liked the network graph, I'm always curious about how much referrals matter, thanks for keeping track of it! In your case referrals mattered a lot. You didn't diagram out the influence lines, i.e. who encouraged whom, but I'd guess that would further reinforce the referral strategy.

<comment><AUTHOR> That's a good point. Harder to track and visualize but it would have been interesting. You can roughly assume that anyone in the "invested" column influenced people further down the tree from them.

</comment></comment><comment><USER8> Glad to see more posts like this coming out of the woodwork. Our CEO (at Profitably) just published a really detailed account of our fundraising, required reading for entrepreneurs that are raising! <http://profitab.ly/h49ues>

<comment><USER9> Why didn't you just link to [http://blog.profitably.com/post/4064020554/a-tale-of-two- fin...](http://blog.profitably.com/post/4064020554/a-tale-of-two-financings) instead of [http://5z8.info/uniqueinvestmentopportunity_h8e8mk_facebook-...](http://5z8.info/uniqueinvestmentopportunity_h8e8mk_facebook- hack) ?

<comment><USER8> Fair point. It was actually easier to get that url since I had bitly open.

</comment></comment></comment><comment><USER10> YC companies seem to have that social proof by a first investor from the start (ie when they are accepted).

</comment><comment><USER11> What was your burn rate at this point?

<comment><AUTHOR> Our actual burn rate was pretty low (~$10K/mo) but it was also unsustainable. No one was being paid and we were just finding enough money to keep a roof over our head. Our "true" burn to keep going would have been much higher than that.</comment></comment>