Talk:Matrioshka brain

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The nested Matrioshka brain is indeed the most energy efficient, but it's actually close to the worst mass-efficient implementation. The larger, outer shells have most of the mass, but tap very little power, and perform very little computation compared to the inner shells (though you get better computation-per-unit-power due to reduced thermal noise).

For best mass efficiency, you'd use a single Dyson sphere that was as small as possible will still having a cool enough outer surface to have a reasonable Carnot efficiency (assuming you're running a heat engine; this is limited by the maximum temperature of your inner surface material and your working fluid, and gives you something with a radius anywhere from Mercury's orbit to Venus's, depending on what your efficiency threshold is).

A photovoltaic Matrioshka brain could have better efficiencies, though its computation efficiency might be lower. This is governed by the requirement that your working voltage be at least 4kT in order to be reasonably noise-resistant (if you're using electrical computing elements).

Actually, I should probably just add all of this with a bit more detail to the article later.

[Chris]

Actually, most of the mass goes into the radiators and cooling fluid (not the energy collectors, computational units or communications interfaces). As the design for the MBrain calls for probably 5-10 layers constructed using all of the available materials in orbits ranging from within Mercury to outside Pluto the factors Chris points out *are* taken into account. The multi-layer design is optimized by function depending upon each layer's operating temperature (energy density) and materials availability. This probably means that most of the computation is done in the inner layers while most of the information storage is done in the outer layers (presumably using caching methodologies to minimize information retreival delays). The architecture evolves over time (in the early years) as the planets are disassembled and various elements move moved to orbits where they are most useful. For example iron could be used as a liquid coolant for the most high temperature layers, as radiator material (esp. when combined with oxygen) for the intermediate temperature layers and as an information storage material (using its magnetic properties?) in the coolest outermost layers. Getting the optimal location for all of the available material depends upon the material designs of the specific layers and the computing architectures which are in turn determined by what the MBrain wants to "think" about and how it goes about doing so.

I suspect during the early evolution of the MBrain there is a movement of the most useful elements (C,N,O,Al) into the inner solar system and some of the heavier elements (Fe,Co,Ti) to the outer solar system. The picture gets quite complex as while W is a very high temperature material it isn't very abundant. Many carbides (SiC), nitrides (Si2N3), and oxides (Al2O3) have high melting points and could be relatively abundant if you move the outer solar system material inward. It is a reasonably complex problem once you take solar system element abundances and the physical properties of various elements and compounds into account (which I have done). Combine that with the relatively unlimited nature of computing architectures and it becomes horrendously complex.

The rate of evolution changes significantly after one has disassembled all of the planets because then one has to start the disassembly of the Sun itself. That takes a long time due to the massive energy requirements of lifting material out of the Sun's huge gravity well. One wants to separate out the heavier elements and probably put the H & He back into the Sun. This not only lengthens the lifetime of the sun (by reducing the fusion rate) but gives you the heavier elements for construction purposes without having to breed them (which is an expensive and somewhat messy process). Decreasing the diameter & temperature of the Sun also allows you to move the computational nodes inward within the solar system thus decreasing the inter-computational node information transmission time.

Please do not quote any of this in the Wiki entry directly as it would tend to make the top level entry quite long (which is probably undesirable) and the information is semi-speculative (i.e. not really "verifiable") on my part. Thanks

If any wiki authors would like to contact me directly with questions, they may do so at Robert.Brad__REMOVE-THIS__bury at gmail.what-you-would-expect.

[Robert]

Is there any way at all to guestimate a resonably plausable number for the computational capacity of one of these. I suppose a crude way would be to assume the entire output of the sun being used as efficiently as possible for computation and then multiplying that number by a an efficiency factor of anywhere from 99.99% to 0.000001%

Contents 1 Improper Links 1.1 Further Link Updates 2 A Name Correction: *Ray* Bradbury 2.1 Look Again

[edit] Improper Links

It looks like I goofed! Sorry. I "updated" the link to the Matrioska Brain "homepage" to point to the only working copy of the page I could find of the material on the Web, and didn't update the description of the link. My severe bad - as this implied the site belonged to Robert Bradbury when it did not. The page's original author has objected, so I've changed the URL to the orginal URL, even though this url still is not functional.

I will check occasionally, but if the "main" page doesn't go back up within the next couple of days, I'll just take the link out rather than either point to a resource the author does not wish to be associated with or leave a dead link in the article.

Beowulf314159 18:58, 21 January 2006 (UTC)

[edit] Further Link Updates

Due to ISPs now blocking some ports it may take some time before the original Matrioshka Brain Home Page URL can be fully restored. In the meantime the URL with an alternate port should work http://www.aeiveos.com:8080/~bradbury/MatrioshkaBrains/index.html

Robert

Thanks, I've updated the main article with the new link - Beowulf314159 12:51, 25 January 2006 (UTC)

[edit] A Name Correction: *Ray* Bradbury

This article says, "The term Matrioshka Brain was invented by Robert Bradbury...". Do you really mean Ray Bradbury? If so, please consider correcting it. I'd also like to see a reference to the article or story in which he coined the term.

Thanks,

Roy Beatty —The preceding unsigned comment was added by Rrbeatty (talk • contribs) 03:36, 4 December 2006 (UTC).

[edit] Look Again

Did you miss Mr. Bradbury's fairly lengthy post on this discussion page? Or did you just not read the signature? He is a distinct entity from Ray Bradbury.

209.115.173.21 06:58, 14 December 2006 (UTC)

This is Robert, and I am not going to bother with the Wikipeida formatting requirements. It is my current understanding, given the Bradbury Memorial, and my father (Rudolph Bradbury)'s pursuit of the family geneology that I am Norris E Bradbury's 5th cousin twice removed and Raymond Douglas Bradbury's 6th cousin twice removed. We are likely related but not one in the same. —Preceding unsigned comment added by RobertBradbury (talk • contribs) 17:13, 2 November 2007 (UTC)