Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Starcloud

ycombinator.com

Post reply on HN
Print view View original

301–310 of 325 posts

Re: Starcloud

#301

Post by Lanzaa »

godelski wrote: post #209
Lanzaa wrote: post #36

Earlier quoted context omitted.

Passive cooling refers to "passive radiative cooling"[0]. This is a well established technique, but I have doubts on how well it will scale with the heat generated by computation. Radiative cooling works by exploiting the fact that hot objects emit electromagnetic radiation (glow), and hot means everything above absolute zero. The glow carries away energy which cools down the object. One complication is that each glo…

This is exactly right, and an important fact is that there is a limited bandwidth for heat radiation. So essentially they need to create a giant lightbulb... > Additionally, deep space is cold, which is accurate in that the "effective" ambient temperature is around -270°C, corresponding to the temperature of the cosmic microwave background. There's a lot of bad information in their document too. This -270C temperatur…

FWIW, i think their description for the radiation shielding is fine. Your analysis is off. If we assume the spherical case, the mass of the shielding is proportional to surface area, not the volume[0]. You might be confusing general radiation shielding and thermal shielding. Thermal shielding is easier because you can point things towards the sun, earth, and moon.

I am more concerned about heat dissipation, which should scale with surface area, but heat generation scales with compute volume.

[0]:

shell thickness, t

compute radius, r

shell volume is (r+t)^3 - r^3 = 3 r^2 t + 3 r t^2 + t^3 = O(r^2)

shielding/compute is O(r^2)/O(r^3) = O(1/r), ie their linear decrease

Re: Starcloud

#303

Post by dakr »

There is a lot of handwaving going on here. The below, however, is an egregious misunderstanding of how percentages work. That, or it betrays very sloppy work. Doing it right would actually make the specific case they make stronger.

"There are also potential opportunities to leverage the fact that the speed of light in a vacuum is 35% faster than in a typical glass fiber."

This is just wrong. The speed of light in a fiber is ~2/3 slower than in a vacuum. That means that the speed of light in a vacuum is 50% faster than in a fiber, not 35% (~1/3) faster!

Re: Starcloud

#304

Post by [deleted] »

godelski wrote: post #209
Lanzaa wrote: post #36

Earlier quoted context omitted.

Passive cooling refers to "passive radiative cooling"[0]. This is a well established technique, but I have doubts on how well it will scale with the heat generated by computation. Radiative cooling works by exploiting the fact that hot objects emit electromagnetic radiation (glow), and hot means everything above absolute zero. The glow carries away energy which cools down the object. One complication is that each glo…

This is exactly right, and an important fact is that there is a limited bandwidth for heat radiation. So essentially they need to create a giant lightbulb... > Additionally, deep space is cold, which is accurate in that the "effective" ambient temperature is around -270°C, corresponding to the temperature of the cosmic microwave background. There's a lot of bad information in their document too. This -270C temperatur…

[deleted]

Re: Starcloud

#306

Post by handfuloflight »

handfuloflight wrote: post #296
jsheard wrote: post #74

Earlier quoted context omitted.

Apocalyptic scenarios where terrestrial communication methods going back over a century are no longer feasible, but we can still readily talk to space? And maintain/replace the stuff we have up there?

Like the commenter, your error is thinking the hedge is for you. And what's more—you're assuming the scenario must be total destruction, there's a gradation of disruption where this hedge remains feasible and even vital.

Like [the other commenter]*

Re: Starcloud

#307

Post by falcor84 »

alfiedotwtf wrote: post #133
hnuser123456 wrote: post #110

Earlier quoted context omitted.

Obviously use the heat pumps to concentrate the thermal energy up to 2700k, then conduct it along a bunch of tungsten filaments, now it's the world's biggest incandescent lightbulb on top of being the first datacenter in space. Maybe get it up to 4000k for a more modern lighting look. Guess we're gonna assume the dark forest hypothesis is false.

Could they concentrate the energy and beam it down to earth as a source for electricity generation on the ground?

My thermodynamics is rusty, but if they could concentrate it, that would mean that it's part of the "free energy" that could be used to power the data center itself, and given that it's impossible in practice to have perfect efficiency, there will always be excess heat that cannot be concentrated (entropy going up).

Re: Starcloud

#308

Post by whazor »

echoangle wrote: post #103

I’m still not sure how people can believe this, this makes zero sense to me. There is no easy passive cooling in space, getting rid of heat is a major problem. And you need more redundancy because the radiation will crash your computers. And launch is very expensive of course. And the whole presentation is completely ludicrous. Look at table 1 in the linked PDF and tell me you’re serious. There is no additional cost…

Radiation will do much worse than crashing your computers, it might alter memory and make you go insane. Especially with GPUs that is extra bad because of all the floating point operations where you wouldn't notice some bits being messed up.

Re: Starcloud

#309

Post by devops000 »

FridgeSeal wrote: post #289
alfiedotwtf wrote: post #133

Earlier quoted context omitted.

Could they concentrate the energy and beam it down to earth as a source for electricity generation on the ground?

Energy efficiency? From my AI data centre project?? Get out of here, we’re only interested in getting rich, we don’t actually care about doing something _useful_ for people.

Read "Ayn Rand - the virtuous egoist"

Re: Starcloud

#310

Post by echoangle »

whazor wrote: post #308
echoangle wrote: post #103

I’m still not sure how people can believe this, this makes zero sense to me. There is no easy passive cooling in space, getting rid of heat is a major problem. And you need more redundancy because the radiation will crash your computers. And launch is very expensive of course. And the whole presentation is completely ludicrous. Look at table 1 in the linked PDF and tell me you’re serious. There is no additional cost…

Radiation will do much worse than crashing your computers, it might alter memory and make you go insane. Especially with GPUs that is extra bad because of all the floating point operations where you wouldn't notice some bits being messed up.

Right, that was generous. It can also permanently destroy your chip, not just crash it.
Post reply on HN