Where the Carbon At? Wednesday, May 9 2007
In the long term, I am concerned that we will fuse all the light elements and break apart all the heavy elements. This course of action would lead to an overabundance of iron. With an atomic number of 26, iron consumes more than three times as many protons, neutrons, and electrons more than our favorite element, carbon. Iron is a waste. Carbon is superior because of its versatility, but more importantly, because it can form the strongest bond in all of chemistry – the hallowed sp2, or carbon-carbon bond. This powerful bond will allow us to build extremely small, rigid structures suitable for nanocomputers, which we’ll all call home someday.
One thing is certain. We must build a Shkadov thruster – a stellar engine – and head for IRC+10216 (CW Leo), the closest carbon star. CW Leo has relatively low gravity because it is a red giant, so it is constantly spewing carbon material out into the interstellar medium. The star is almost 500 light years away, so we’d better get started soon. Even if it takes billions of subjective years, we must go there eventually, because otherwise we will run out of carbon to build fun stuff. When we get there, we can start siphoning off the carbon-rich atmosphere of the star, and keep withdrawing carbon until we can withdraw it no more.
We should avoid the scenario where we fuse all our light elements into iron prior to making it there. Unless we desperately need the energy more than the free carbon, it would be foolish to pursue fusion past a certain point. It seems plausible that we can drastically reduce our energy consumption by implementing ourselves on almost-reversible computers, so it seems a higher premium will be placed on matter (particularly carbon) than energy. In a worst-case scenario, if we collectively run out of energy by devouring the Sun and fusing everything up to carbon, we might need to agree on a civilization-wide shutdown until we make it to CW Leo, or find some way of getting energy from the vacuum.
Edit: all the above is mostly pointless because I now realize that any star can be artificially compressed into a carbon star. Natural carbon stars require no extra effort, though.
You can, however split the iron using the energy from this very matter.
The iron is at the lowest energy point from the nuclear fusion/fission perspective. But an iron star has at least some gravitational energy potential left. Just compress one of those metalic stars and a black hole will provide the energy via the Hawking radiation. To split the remaining iron to carbon.
Michael – Jupiter, at a volume of 1,321 Earths and made almost entirely of Hydrogen is quite a bit closer. We could make our own with relatively well-understood processes (H–>HE via CNO cycle and then onwards to C) a bit simpler than a 500 LY trip. We haven’t even achieved simple, sustainable fusion. I believe we’re in the middle of a logistic function growth in technology. It’s gonna taper off well before we run out of carbon
I am talking about what we have to do once we exhaust all the solar system’s carbon.
Even with static technology we could still reproduce exponentially and therefore could consume all the matter relatively quickly.
We haven’t yet achieved sustainable fusion but it’s pretty obvious we will eventually.
There is something ironic/quaint about being so advanced that we will have nanotechnology, sustainable fusion, and perhaps even interstellar travel, yet still needing to put on our little miner’s caps and shovels to go dig up some carbon.
I’d like to think that at some point before converting all matter into end-of-line iron we’d come up with any alternative (such as listed in original blog and comments). Heading to CW Leo implies that we squandered both resources AND intelligence.
“because it can form the strongest bond in all of chemistry – the hallowed sp2, or carbon-carbon bond. ”
Der what? To clarify:
1. A carbon-carbon bond is a bond between two carbon atoms. This bond is covalent (electrons are shared between orbitals). There are actually three different types of carbon-carbon bonds, the single bond, double bond and triple bond, where one, two, and three pairs of electrons are shared, respectively.
2. The more electron pairs are shared, the stronger and shorter the bond is.
3. None of the C-C bonds are exceptionally strong. The H-H single bond is stronger than the C-C single bond, the C=O bond is stronger than the C=C bond, and the N~N bond is stronger than the C~C bond.
4. In order to share its orbitals, carbon hybridizes them from a normal state into a shareable state. sp3 hybridization is for four single bonds; the s orbital and the three p orbitals combine to make four hybrid orbitals. For a double bond, sp2 hybridization produces three hybrid orbitals, plus an extra one for the double bond, and for a triple bond, sp is used.
5. Carbon’s great utility comes from its ability to bond to itself, hydrogen, nitrogen, oxygen, and many other elements, forming long molecule chains (organic molecules), which are very useful because there are so many possible arrangements. You can design an organic compound to do just about anything within the bounds of the laws of physics.
“because otherwise we will run out of carbon to build fun stuff.”
All you need to make carbon to build stuff is iron or any other heavy element and a hell of a lot of energy. If you smash up an iron atom with enough energy (in the GeV range), it will break apart into component nuclei. Although I still can’t see why we wouldn’t simply keep some matter in the form of carbon in the first place.
“We must build a Shkadov thruster – a stellar engine – and head for IRC+10216 (CW Leo), the closest carbon star.”
Uh, you do know that there are lots of *other* stars which are made of hydrogen, which can be fairly easily fused to carbon?
“I believe we’re in the middle of a logistic function growth in technology.”
I believe that the Flying Spaghetti Monster will swoop in and develop new technology for us. Seriously, is there any evidence technology- which has been progressing for fifty thousand years- is just going to hit a magical brick wall and then stop?
“Unless we desperately need the energy more than the free carbon, it would be foolish to pursue fusion past a certain point. ”
We already have a mechanism for implementing this; it’s called the marketplace. Price of carbon goes up, people stop fusing carbon. Price goes down, people start fusing carbon.
“and just compress them until they fuse all their light elements into carbon, ”
When you compress a star, you’re expelling a great deal of GPE from the star as heat. When the star runs out of fuel to fuse, it will also have lost a lot of GPE, and so all the carbon will collapse onto a white dwarf (natural white dwarfs are primarily made of carbon and oxygen). Getting a solar mass worth of material off the surface of a white dwarf is going to be a very serious pain energetically, because the GPE of the thing is so high. The amount of energy required to harvest the carbon is roughly comparable to the amount of energy you’d get from fusing the carbon, which is in turn comparable to the energy of your average supernova.
These discussions are a little frivolous on account of the many unknowns, but I like this line of thought, it’s a new one. I take the real message to be that the “center of gravity” of the post-Singularity technosphere should be moved towards CW Leonis, whether by making a Shkadov thruster for Sol, or just by shooting the core aggregate of intelligence there at ultrarelativistic velocities. If carbon is so valuable, that might be a better way to get there – travel a la Shkadov is still very slow. And of course, CW Leonis might itself only be a waystation.
The bigger question here (and in the previous post) is, what is the optimal way for a civilization capable of turning universe into computronium to proceed? If one adheres to the view that everyone will want to stick together because of communication lag, one might suppose that the proverbial near-lightspeed expansion of von Neumann probes will be carried out by (relatively) dumb agents whose agenda is a rather passive one – just go out and husband galactic resources, for those future ages when they will be wanted. Another question concerns the rate at which the data storage needs of the individual members of the core will expand. However much bigger than a contemporary human mind the capacity of a Matrioshka-brain may be, it’s still finite, and can only house so many individuals; and the more they each want, the smaller the carrying capacity. Under certain circumstances (certain goal systems, for example), one can imagine a population of ballooning post-Singularity minds who engage in a desperate migratory “burning of the cosmic commons” (Robin Hanson), building a fleet more massive than anything that could be made in one solar system, and which shoots from star to star picking up more atoms in order to maintain individual complexity growth rates without imposing the communication lags deriving from spatial separation. When you throw in the option of a civilization-wide slowdown, and of mining stars for atoms (e.g. create an artificial outflux of hydrogen atoms from a star, and then fuse them in space, into the desired distribution of elements), you get a multidimensional optimization problem which might make an interesting paper.
As I said, it’s all a little frivolous – I’m sure that anyone who understands this discussion has far more urgent things to do – but such calculations and scenarios do concretize one’s thinking about the post-Singularity universe, so it’s worthwhile that someone should think about them… in their recreational time.
Thanks.
this information contain knowledge of carbon carbon bond and strongness between them. I have information about there application in space elavator how they are increse there bonding long.