Category: Super-Tech

Clarke Tech, God Tech and just plain cool

Dark Matter Stars and SETI

Any species which advances beyond “the Singularity” stage of development has essentially become immortal and is faced with the inconvenient fact that natural power-sources like stars aren’t. While they might persist for eons there will always come a day when the fusion flame goes out and most of a star’s mass is left to cool to ambient temperatures.

But are there other options for powering stars? Two new sources of power have emerged in recent arXiv.org submitted papers, Black Hole Quasi-Stars and Dark Matter Stars. Let’s have a look at those ideas.

Quasistars: Accreting black holes inside massive envelopes

…Begelman, Rossi and Armitage describe a scenario in which an accreting black-hole forms the core of a star-like object. A star is essentially an object in which the pressure created by inward pull of gravity is counteracted by the outward pressure of escaping electromagnetic energy – either indirectly as particle agitation (what we call ‘heat’) or directly as radiation pressure. In side a quasi-star the hot layers of gas above the black hole are bloated into a heat-pressure supported radiating surface, a luminous star, by the energy of infalling matter. As matter falls into a black hole it can lose up to ~5.7% of its mass energy as radiation – this is more efficient than a star’s piddling 0.7% energy production via nuclear fusion.

This might sound rosy as a long-lived star power-source but it has a down-side. It’s violently unstable because of opacity. Opacity is the tendency of a gas to get in the way of radiation passing through it – it’s what turns radiation into ‘heat’. Too much and the radiation gets pent up until something gives… in this case the gaseous envelope that looked so much like a star gets blown away and the naked raging x-ray source that is an accreting black-hole is revealed. Not healthy.

A nicer way to stoke the flames is via dark matter… except we still don’t really know what it is. One candidate is WIMPs – short for Weakly Interacting Massive Particles – and by “Weakly” they interact via the Weak nuclear force as well as gravity. With the least number of assumptions and actual prediction by minimal extensions of the Standard Model (i.e.how known particles and forces work), WIMPs are prime candidates for the super-abundant Dark Matter that out-masses “light matter” 5 to 1. Because they’re Weak force particles, they happily are their own antiparticles and thus a good energy source for a star.

A recent reference…

Dark Stars: Dark Matter in the First Stars leads to a New Phase of Stellar Evolution

…in which the effect of WIMP annihilation on the first stars is discussed. Basically a low mass newly minted star glows brightly from Dark Matter when it gets to about 17 AU across and 0.6 Solar Masses, then it gradually accretes more mass and becomes 800 Solar Mass behemoth radiating 1,000,000 times as bright as the Sun, lives a million years, then dies by collapsing directly into a Black Hole, perhaps forming the core of a Quasi-Star?

Such very early objects allow the super-massive Black Holes at the cores of Galaxies to form rapidly – some eventually massing as much as the Milky Way’s visible matter (~60 Billion Solar Masses.) That doesn’t sound like a very long-lived star candidate, but further work has revealed a light-weight version…

Dark Matter annihilations in Pop III stars

…with the right density of WIMPs (about a billion per millilitre) a 20 Solar Mass star can be ‘frozen’ and still be happily burning on the Main Sequence for as long as the current age of the Universe. That’s a life extension of about ~2,000 fold, so it’s definitely enticing to imagine ETIs shepherding Dark Matter into the Galactic Core and giving their stars a life-extension. With a mass-energy conversion efficiency of ~60% the Galaxy’s 1.2 trillion Solar Masses of Dark Matter could keep its stars burning at 30 billion Solar Luminosities (current output) for ~350 trillion years. Much of that luminosity is from over-active O, B and A stars, so the useful light level is more like ~3 billion, thus 3.5 quadrillion years of starlight is available for all to bask in. Not forever, but substantially better than the darkness awaiting the natural Galaxy in that epoch.

Eventually something better will be needed. But just what will replace starlight?

Another WIMP Star paper is Low mass stellar evolution with WIMP capture and annihilation …which discusses the effect of WIMP burning on low mass stars like the Sun. As already pointed out the stars’ lifetimes are enhanced greatly – after 30 billion years the model star looked as it did at age 0.1 billion. In other words so long as the WIMP supply lasts the structure is stable and nuclear fusion takes a back-seat. The star can last for trillions of years given the right WIMP halo. Gravitationally bound structures composed of more than two roughly equally massed objects are inherently chaotic and prone to eventually fall apart – even the Galaxy will disperse over about 10 million trllion years. Nothing lasts forever.

Solar Energy Storage breakthrough?

MIT researchers have developed a new way of storing solar energy – use the energy to breakdown water into hydrogen and oxygen, which can be used in a fuel cell later…

MIT solar breakthrough

…which may sound a bit like old news but they’ve developed a new high-efficiency way of doing it at low temperatures. Another advance announced a few months back involves a new thermoelectric generator potentially able to work at 85% of the Carnot Limit.

It’s the Whole, not the Part…

Uber science-writer Carl Zimmer muses on some utterly fascinating research on rewiring E.coli’s gene networks…

The More We Know About Genes, the Less We Understand

In the latest issue of Nature, scientists reported an experiment in which they wreaked havoc with E. coli’s network. They randomly added new links between the transcription factors at the top of the microbe’s hierarchy. Now a transcription factor could turn on another one that it never had before. The scientists randomly rewired the network in 598 different ways and then stepped back to see what happened to the bacteria.

You might expect that they all died. After all, if you were to pop open the back of an iPod and start linking its components together in random ways, you’d expect it to crash. But that’s not what happened.

About 95 percent of the rewired bacteria did just fine with their new networks. They went on with their lives, feeding, growing and dividing. Some even performed better than microbes with the original wiring, under some conditions.

…which is an incredible result. Carl muses there’s “something about gene networks” – gene networks being the program that controls an organism’s DNA activities – which lets them handle massive perturbations like a total rewiring. The puzzle is profound, but it indicates a great truth in biology – the whole, the organism, is greater than the sum of its parts, the genes, proteins and so forth that make it. They work together in a harmony that may have a higher-level abstract structure that allows great stability.

Here’s the Nature paper in abstract… Evolvability and hierarchy in rewired bacterial gene networks Ref: Nature 452, 840-845 (17 April 2008) | doi:10.1038/nature06847

…and it’s truly an amazing result. But just what does it mean? I think it means that genetic mutation – via gene changes or changes to regulator sequences – is just one step in the process leading from genome to living thing. The whole of an organism acts as an “editor” that decides if a DNA change makes sense – that’s the first level of “natural selection” and it seems a lot more able than the old “random mechanism” view that treated cells as intricate clockwork. Instead the cellular system is much more responsive and dynamic in a way we have trouble grasping because so much collective molecular behaviour is involved.

The Choices Ahead of Us

Human beings may create their successors – intelligent software, either derived from us directly or created de novo – and They may be immensely more powerful than us. One thing they might do, to capture the Sun’s light, is build a Dyson Shell. Paul Gilster’s Centauri Dreams covered a recent news bite on a search for Dyson Shells, and sparked a huge discussion…

Dyson Shells and ETIs

…to which I added a few comments. One in particular is in two parts… Part 1 Part 2

…the end of Part 2 being something I want to share further here…

In the end it seems like an aesthetic choice – do we keep planets and remake them? Do we stay human, or become Artilects? Should brute matter be remade into computronium and the Sun enshelled as in a Matrioshka Brain? Or should we be more subtle? Darwinnowed gene-brain hybrids, like us, are motivated towards exponential growth, but Transformed Humans and/or Artilects will be able to bypass all that and reach for a whole different motivation set.

Ezekiel wrote 2600 years ago “Turn from evil, and do good.” So much of society, its moral-systems and educational systems focus on the first, but there’s no clear road for what the second half is all about. What is good for us, as evolved creatures, may seem flawed and limited to beings able to reflect upon all levels of their programming. They will have all our recorded history to see the fruits of our attitudes and philosophies and there’s no telling what that might lead them to conclude.

ETIs – if They persist for billennia – will have faced the same end-point of Darwinian evolution, and will have passed Judgement on themselves as a species. Speculating on Their choice and its consequences may well help us make our own, before that choice is taken away by circumstances. At some stage we will run into the limits of social organization driven by Darwinian mechanisms, and the end of it might be catastrophic.

…the idea of impending Judgement has a lot of old religious references that I am loath to encourage. While I believe in Jesus Christ, I am unimpressed by the many and varied interpretations of his words on “the End of the Age” and I am equally dubious about present day fulfillments of the John the Elder’s Apocalypse. Christian creeds all affirm JC will come again to Judge the living and the dead, and I believe in the Resurrection of all by the Omega Point, God-as-Singularity. But there’s another “end of days” coming our way as we reach the limits of our Earth-bound existence, and contemplate the creation of intelligence fundamentally different to our own.

Some approach the task with fear. They imagine to create intelligence will be animating the “Image of the Beast”, foretold in the Apocalypse. I don’t think so. If we create new minds we will only be fulfilling the Image of God within us. Yet we must be very careful not to infect this new life with the blight in our own souls from our evolution’s necessities.

Cost of coal

Let’s look at the cost of coal-fired power over the long term – aside from the environmental impact, which is worrying enough. Combustion of carbon (the main component of coal) produces 393.52 MJ/kMol – as 1 kilo-mole of carbon is 12.011 kg, that’s 32.76 MJ/kg. But coal also contains a lot of “ash” – incombustible junk – and so typically coal burns about 27 MJ/kg. Cheaper power-utilities in China dump the ash straight into the exhaust stream, which is rather nasty for everyone downwind, but in developed countries the stuff is captured and sold as a concrete ingredient, if it’s not too radioactive. Yes, radioactive, from all the uranium and thorium that naturally occurs in some coal-fields.

That aside a ton of coal typically costs $20/ton to dig up, crush and get to the furnace. Once there the stuff is burnt and the heat boils water into super-critical steam, pushing turbines. Some heat is recovered in a good coal fired plant, getting about 40% efficiency from coal lump to power-meter at the station’s transformers upping the voltage for transmission. Thus every megawatt produced means about 2.5 megawatts of heat from burning coal, about 0.0926 kg coal burnt and about 0.338 kg of carbon dioxide produced. A 500 megawatt plant thus needs to burn 46.3 kg/second or 4,000 tons of coal a day. And the plant can’t slack off because the boiler and furnaces need to burn that ALL the time. Design limitation. Thus a coal plant costs about $80,000/day in coal-mining. About $29.22 million a year. Over 30 years it burns 43.83 million tons of coal, makes 122 million tons of CO2, 7.7 million tons of ash and costs $876.6 million in coal-mining costs (non-adjusted for inflation.) Thus the $750 million dollar coal-plant costs another $876.6 million in coal-mining for 500 MW for 30 years. Throw in the costs of running the thing (about 30% extra) and, in reality, the power costs maybe $2.11 billion (non-inflation adjusted) – about $0.016 per kW.hr. So the margin of selling it for $0.05/kW.hr is quite good.

But coal isn’t always that cheap. Here in Queensland, Australia, coal is cheap – we have some of the best anthracite (high carbon coal) in the world. Our Government power companies seem to burn it for close to cost prices. If you have to buy it on the market, not just mine it, then it costs ~$US 120/ton or so. Then the costs jump to $0.0457/kW.hr and Solar Powersats look a whole lot more attractive. No wonder places like Japan are interested.

What about a “carbon tax”? If, like the nuclear industry, coal-plants had to cost-in carbon dioxide disposal things get interesting – estimates of $20/ton are bandied around as viable. That means about $60 per ton of coal burnt. Add that to the above and we get at worst a cost of $0.0657/kW.hr. Nukes start looking like the cheapest option, unless our powersats start coming down a bit more.

So how many kW.hr does a 500 MW power-source produce in 30 years? Assuming 263,000 hours in 30 years that’s 131.5 million kW.hr. If we had a solar panel on the ground only about ~ 25% of those hours would be producing energy at full strength, due to the day/night cycle and cloud-cover. Thus, to get the same power overall ground-based solar needs x4 the expected power supply, minimum. With batteries it’s more like x5 because of the inefficiency of charging/discharging batteries. Thus, if power cells cost ~ $4/W (installed with power conditioning & storage) and we want 1,000 W continual supply we need 5,000 W of cells, and it all costs $20,000. Repaid over 263,000 hours it costs $0.076/kW.hr. With interest, costs spiral to ~ $0.25/kW.hr. But solar PV cells are coming down in price all the time. Nanosolar is planning on selling for ~$1/W, thus implying eventual reduction of price to ~ $0.0625/kW.hr. But only if we’re repaying over a leisurely 30 years. Some PVs decline by ~ 10% every few years or so. If we want a 10 year repayment time we’re back up to $0.19/kW.hr.

Solar Power Satellites re-examined

Robert Zubrin’s Entering Space is a passionate defense of the idea that humanity needs to commit to colonising another planet – specifically Mars – before many other space-related concepts can become viable. One money-making venture in space that Zubrin trashes along the way is the Solar Power Satellite or Powersat a concept first proposed in the 1960s by physicist Peter Glaser, and since then extensively studied by NASA and the DoE in the US, as well JAXA and the ESA.

Zubrin’s analysis is scathing for anyone with hopes of powersats being a commercial prospect. Here’s what he assumes and computes in his argument…

(i) Insolation averages ~ 1300 W/m^2… a bit low, but not by much. References give 1368 W/m^2, averaged.
(ii) Power transmission efficiency ~ 50%… low again, typically 63% in the literature
(iii) 15% efficient PVs
(iv) PVs mass 4 kg/m^2… rather heavy.
(v) non-PV mass another 4 kg/m^2 of PV panel… even heavier.

At $40,000/kg delivery costs to GEO a 1 GW (500 MW to the ground) Powersat massing 41,000 tons would cost ~$1.65 trillion to orbit, and double that to assemble. That’s $3.3 trillion total. For some reason his quoted figures double at this point and he says $6 trillion. At 10% interest and maintenance the system annual costs go to $1 trillion (~$0.55 trillion using the corrected figures) and the cost per kilowatt.hour, for 500 MW supplied for 8,766 hours a year, is $228/kW.hr ($125/kW.hr corrected.) Some 2500 times more expensive than the $0.05/kW.hr at the time of writing (1999.)

By his analysis that means launch costs would need to drop to just $4/kg which is impossible using current techniques as that’s 4 times less than the fuel costs needed. Clearly absurd BUT let’s look at his assumptions again. We’ll grant him (i) & (ii) as the figures quoted are close to literature figures. What about (iii)-(v)?

(iii) 15% efficient PVs… well the best commercial cells are heading for 40% and techniques for increasing efficiency are being touted by various labs. One inventor is selling thermoelectric converters with 60% efficiency, while another group has developed nano-antenna collectors potentially 80% efficient. Thus the PV mass could be cut by more than 75-80%.
(iv) Mass density of 4 kg/m^2. Very heavy. The new PVs could be made much lighter by using concentrator arrays (which also cuts the costs of PV converters themselves too.) A system of inflatables could drastically cut the mass of the array – Geoff Landis designed a system massing just 800 tons (plus 500 tons structure) collecting 3 GW in space at 35% efficiency thus massing just 0.364 kg/m^2. All the old DoE/NASA studies assumed about ~ 1kg/m^2 including PVs and structure. Zubrin is wildly off-base.
(v) Double the PV mass in structure and power distribution/transmission systems. Structure can be made using self-assembling inflatables that space-cure into hard structures. Power distribution and transmission masses can be minimised by clever design – I’m doubtful they’d mass 20,500 tons for 1 GW like Zubrin imagines, but they can be heavy. Especially problematic are the heavy slip-rings and brushes needed to transfer power from the rotating collector panels to the non-rotating transmitter. A lot of mass can be saved by reducing the need for power transfer. One design uses movable mirrors focussed onto a non-moving core connected directly to the transmitter. This also reduces the heavy power-cabling needed to carry 1,000 MW to the transmitter.

Moving parts are always a potential problem, but lots of small moving mirrors reduces the impact of one or two mirrors sticking and needing repair. Conceivably those repairs could be carried out by teleoperated machinery.

Let’s call the powersat mass ~ 1 kg/m^2 – not as good as some designs, but better than Zubrin’s Strawman Argument. So where does that get us? Some 20% of 12.5% percent means the powersat now masses ~ 1025 tons. Delivery cost is still $41 billion to GEO, which is pricey. Zubrin also cuts costs even further by arguing that air-breathing rockets and ion-drive delivery systems can cut LEO then GEO by half each. Thus the powersat costs ~ $10.25 billion delivered to GEO, and double that overall. Some $20.5 billion is a lot to build a power-station supplying just 0.5 GW. Typically a coal-plant costs about $1.5 billion per gigawatt power. Thus to compete a powersat needs its costs reduced by 27-fold. GEO delivery costs need to get down to ~ $360/kg, and construction stay at twice the launch costs, to make powersats viable.

As SpaceX is aiming for $500/kg to LEO I would hazard a guess and say powersats might be a viable commercial option, assuming some reasonable improvements to the technology.

Addenda:(i) Zubrin grants a four-fold reduction in delivery costs to LEO then GEO, then a halving of that due to a mass decrease in PVs and structure. For comparison he quotes the minimum cost of LEO delivery via reusable rockets as ~ $100/kg, thus $400/kg to GEO via conventional means. Thus delivery to GEO, assuming the cost reductions and minimal rocket costs, of 20,500 tons of Powersat costs ~ $2.05 billion, and in total it costs $4.1 billion to set-up. He claims that’s still 3 times too much compared to coal. As I show in the next post that’s somewhat misleading. If we factor in carbon disposal and the cost of the coal burnt, then coal’s effectiveness goes down – especially if you’re paying $120/ton instead of $20/ton for the stuff.

For areas paying hand-over-fist for diesel powered generators, prices of $0.2/kW.hr look quite attractive. If you have no coal and no railways delivering it to your generator, then setting up a rectenna farm made of pre-fab identical components delivered via truck looks like a better deal.

(ii)He claimed a 2,000-fold (really 2,500-fold) price reduction was absurd, but with our 40-fold mass-reduction a 62.5-fold reduction in LEO rocketry prices is then acceptable – $160/kg, less stringent than the $100/kg minimum. If ion-drives can cut the delivery to GEO in half, then $320/kg to LEO is acceptable. SpaceX’s ultimate goal is not much more than that.

Daedalus Component Masses… part 2

(all masses in kg)

PROPELLANT SYSTEM
1st Stage 47400000.00 4228190.00
Helium-3 Fuel 27600000.00 2nd Stage Helium-3 Fuel 2450000.00
Deuterium Fuel 18400000.00 Deuterium Fuel 1630000.00
Insulation Insulation
Fuel Tanks 31500.00 Fuel Tanks 19500.00
LH2 Tanks 407.00 Manoeuvre Tanks 460.00
LH2 Tanks 360.00
Fuel Tanks 98500.00 Fuel Tanks 8870.00
Uncommitted Mass (V.O.) 1300000.00 Uncommitted Mass (V.O.) 119000.00
Total= 5.16E+07
PAYLOAD BAY 507000.00
Committed Bay Structure 50000.00
Sensing and Communications (V.O.) 110000.00
Subprobes(V.O.) 245000.00
Service Wardens (V.O.) 45000.00
Shield Cloud (V.O.) 5000.00
Dust Bugs (V.O.) 2000.00
Beryllium Payload Shield 50000.00
TOTAL MASS ESTIMATE 54670415.61

Daedalus Component Masses… part 1

Daedalus Starprobe Component Data…

(all masses in kg)

DAEDALUS
Starship Component  Masses (kg)
PROPULSION SYSTEM 1544427.51
1st Stage 1229636.60 2nd Stage 314790.91
Reaction Chamber(s) 219000.00 Reaction Chamber(s) 22100.00
Excitation Field Coils 125000.00 Excitation Field Coils 43600.00
Titanium Coil Supports 241000.00 Titanium Coil Supports 90600.00
Ignition Assembly 307000.00 Ignition Assembly 81000.00
Charging Circuit Supports 21000.00 Charging Circuit Supports 5900.00
Pellet Injector Pellet Injector
Capacitors 29600.00 Capacitors 790.00
Al Superconducting Coils 36.60 Al Superconducting Coils 0.91
Uncommitted Mass (V.O.) 287000.00 Uncommitted Mass (V.O.) 70800.00
THRUST STRUCTURE 75000.00
1st Stage 50000.00 2nd Stage 25000.00
SERVICE BAY 915798.10
1st Stage 740468.00 2nd Stage 175330.10
Core 645000.00 Core 132000.00
Thermal Shielding Thermal Shielding
Gold 578.00 Gold 55.10
Rhodium 2890.00 Rhodium 275.00
Iconel Base 2000.00 Iconel Base 2000.00
Power Supplies Power Supplies
Buffer Capacitors 30000.00 Buffer Capacitors 3000.00
Nuclear Reactors (V.O.) 60000.00 Nuclear Reactors (V.O.) 38000.00
Total 9.16E+05

A real Flying Saucer from the 1960s

“Star Trek” (1968), “2001:A Space Odyssey” and “The Time Machine” (1960) mentioned orbiting nuclear weapons, but few details have arisen of how advanced such plans were. Mark Wade’s Encyclopedia Astronautica discusses one US design which, oddly enough, is a flying saucer…

NAA Manned Bombardment and Control Vehicle

…armed with four H-bombs and controlling potentially dozens of orbiting nuke platforms. A rather scary prospect which, as Mark discusses, was possibly developed to the point of drop testing via balloon in outback Australia in the 1960s.

Print your own organs | COSMOS magazine

Body prints! Imagine reduplicating your own body from a high-resolution scan… well it’s not that unlikely given the advances happening in tissue engineering. According to this article: Print your own organs | COSMOS magazine it may be a reality 10-30 years from now.

May be.

Our understanding of the genetics of cell differentiation is advancing rapidly and may well allow our own stem cells to be arranged and activated into whole organs, including blood vessels and nerves. Eventually I think we’ll be able to “print” whole functioning bodies – with sufficient resolution, even reconstituting brains.

However what will the legal/ethical status be of people who are dead and yet still existing as records of their bodies/brains? Alive? Half-life? Or legally dead? Will a “reprint” be legally a person? Or merely a “meat puppet” of a dead-person?

I mean that as pejoratively as the word “sock puppet” is meant on the Web. What rights will reprinted dead people have? If any?