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The physics of information processing superobjects: Jupiter brains (1999) [pdf] (jetpress.org)
78 points by inlineint on March 21, 2017 | hide | past | favorite | 13 comments



Jupiter brains must be hollow spheres.

Reason for this: Volume grows cubically, surrounding area has just quadratic growth. Fusion power generation in the core of the Sun is just 270 watts/m^3 similar to human metabolism, but but because the area grows much slower, getting rid of the heat makes the sun very hot.

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What is the computational complexity for Jupiter brain thinking process?

Few options:

1. Tightly connected (like a neural network). O(n^2.373) ... O(n^3) Best modeled as distributed dense matrix multiplication. I think these algorithms are processing time limited, so the communication latency is not a problem. Node to node communication trough hollow sphere helps to remove physical communication bottlenecks.

2. MapReduce like. O(n*log n).

3. Chaotic scale‐free networks. O(n) I think.


Power per cubic centimeter in the sun's core is even lower than that, similar to reptile metabolism. Think of the sun as a giant glowing space lizard.


The one I remembered was that it's about the same energy generating density as a compost heap:

https://en.wikipedia.org/wiki/Solar_core#Energy_conversion


...And that lizard is only as warm as it is because of quantum effects (tunneling).


Could you elaborate?


He's referring to overcoming the Coulomb Barrier in stars that allows fusion to happen at temperatures/pressures that are otherwise too low to fuse.

https://en.wikipedia.org/wiki/Quantum_tunnelling#Nuclear_fus...


Thanks, that's exactly what I was referring to, I should have been more clear.


> Jupiter brains must be hollow spheres.

So... it's the same shape as the biosphere.

This seems to support my current working hypothesis: "sufficiently advanced civilizations are indistinguishable from nature."

I just came across some surprising electron micrograph videos. They show "clumps" of hundreds of cell nuclei streaming through fungal hyphae networks one cell thick, and even some "swimming" against the current.[1] The nucleus isn't just a dumb hard drive holding DNA, but does information processing, sensing, and response as well. There's about 8 miles of fungal hyphae in a cubic inch of forest soil. So overall this represents an astounding potential for computing and sensing/effecting.

I wonder if any bioinformaticists have estimated the theoretical power of such a computing architecture?

[1] https://www.youtube.com/watch?v=za-vIdak3bI&t=25m15s


>This seems to support my current working hypothesis: "sufficiently advanced civilizations are indistinguishable from nature."

How about "large scale optimization processes over long periods of time tend to converge onto functional solutions that meet basic dimensionality requirements."


I read these comments, and I just think how much good it would do someone like Dan Brown to spend an hour with people like you. sigh

More broadly your collective point applies to larger megastructures like Matrioshka Brains (concentric Dyson Spheres). At some point maybe the convergence starts to look like an equation of state for some form of degenerate matter, arranged in very very thin concentric spheres.


> Jupiter brains must be hollow spheres. Reason for this: Volume grows cubically, surrounding area has just quadratic growth.

See the first link. As well, Robin Hanson has some discussions of scaling heat dissipation with optimal pipe technology & branching on his OB blog and in the book form of _Age of Em_.


Any technical solution like convection pipes just rearranges the area needed for heat transfer around. If you have have effective heat transfer you can have more compact computing core. For example, massive radiator disk with edge towards the sun.

I think the choice depends on whether brains are latency limited, local computation limited or communication volume limited. I speculate that they are local computation limited in the largest scale.




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