41–50 of 52 posts
Of course no doubt there’s some requirements that cannot avoid that requirement.
But for the most part needing synchronized time is just going to be a forever problem isn’t it?
What is significance of this?
Distributed systems spend most of their effort on one problem: agreeing on the order of events across machines. Without synchronized physical clocks you have two options. Logical clocks (Lamport, vector) give you causal order but not wall-clock truth, so you can’t answer “did A really happen before B” for events that don’t have a happens-before relationship. Or you run consensus, which gives total order but costs rou…
Earlier quoted context omitted.
So then you need to know distance / roundtrip-length within centimeter precision as well (below 29.98 cm for sub-nanosecond precision… to be precise). Since cm precision is often not possible, is roundtrip-length an estimated average from prior roundtrips?
... why would cm precision be often not possible?
Earlier quoted context omitted.
I wonder I'd that's the math for the ludicrous space data center ideas "floating" around...
Just because you don't understand how something can work doesn't make it ludicrous. People like you are hell bent on destroying what's left of the Earth by turning it into a computer. If we left progress to those without an imagination, we wouldn't even have had a working calculator.
Earlier quoted context omitted.
I wonder I'd that's the math for the ludicrous space data center ideas "floating" around...
Just because you don't understand how something can work doesn't make it ludicrous. People like you are hell bent on destroying what's left of the Earth by turning it into a computer. If we left progress to those without an imagination, we wouldn't even have had a working calculator.
It's the physics of cooling the beasts and the communication delays that make those plans ludicrous.
To turn your assertion on its head, the fact that the supporters don't seem to be able (or willing) to do the math to fact check these proposals is not an indicator that the plans will work.
As a starting point for comparison, the total power budget of the ISS is under 100kW and a single supercomputer rack dissipates about 4x that. What changes to the ISS can be made to get 100x more power and dissipate 100x more heat?
If this wasn't CERN tech I would think I was being taken for a ride. Conventional wisdom is that distributed consensus is not possible at this kind of performance, does anyone have a sense for how this is different and how my mental model is wrong?
> Conventional wisdom is that distributed consensus is not possible at this kind of performance I'm not sure why you would think that? If you can assume the fiber is the same in both directions you know the round trip time is exactly double the latency of the connection. Then you know to phase shift your start time by that much when you get a start signal and you're in sync. Obviously it's not trivial in practice, bu…
Earlier quoted context omitted.
Distributed systems spend most of their effort on one problem: agreeing on the order of events across machines. Without synchronized physical clocks you have two options. Logical clocks (Lamport, vector) give you causal order but not wall-clock truth, so you can’t answer “did A really happen before B” for events that don’t have a happens-before relationship. Or you run consensus, which gives total order but costs rou…
Very good explanation and interesting take on the 'humanity scale' or internet scale significance. I work on a phased array system so significance of white rabbit for me was always sample alignment. Assumed CERN had a similar use case of needing to order (sensor data of) physical events happening far apart. But if we imagine the vast majority of internet and telecom infrastructure is also implemented this way, we can…
What is significance of this?
Distributed systems spend most of their effort on one problem: agreeing on the order of events across machines. Without synchronized physical clocks you have two options. Logical clocks (Lamport, vector) give you causal order but not wall-clock truth, so you can’t answer “did A really happen before B” for events that don’t have a happens-before relationship. Or you run consensus, which gives total order but costs rou…
Haven't looked into this in depth but sub-nanosecond sync for systems up to 10km apart is interesting since 10km is about 33 light microseconds. There is some trickery going on.
Earlier quoted context omitted.
Just because you don't understand how something can work doesn't make it ludicrous. People like you are hell bent on destroying what's left of the Earth by turning it into a computer. If we left progress to those without an imagination, we wouldn't even have had a working calculator.
You're right. It's the physics of cooling the beasts and the communication delays that make those plans ludicrous. To turn your assertion on its head, the fact that the supporters don't seem to be able (or willing) to do the math to fact check these proposals is not an indicator that the plans will work. As a starting point for comparison, the total power budget of the ISS is under 100kW and a single supercomputer ra…
1. There is no real size limit to radiators in space, especially when in solar orbit.
2. High temperature chip architectures can be used, operating at 600K.
3. Heat pipes can bring the temperature even higher, such as to 1200K.
4. Special 3D radiator geometries can be used to optimize heat escape.
5. Metamaterials can be used to optimize photon emission in the best directions.
Together, these will shrink the required radiator area dramatically. Beyond these standard ideas, other exotic approaches exist at the edge of viability.
The ISS in contrast is restricted considering it has to sit in Earth orbit.
You may see this video (AI researched and generated) to grasp some of the points: https://www.youtube.com/watch?v=s7Mv_OcBXI8