Old Blogdrive Posts 9

Tuesday, March 23, 2004
Old bones…

Ancient humans and proto-humans are one interest of mine…


…this is a fascinating blog by Jim Foley at TalkOrigins. He also has a huge image library of the fossils themselves…


…very cool, if you like old bones.

A recent news bite of interest is here…


…the researcher to note is Bob Brain who is probably the world authority on all South African hominids. Or his father – I’m not sure. The Brains, famously, killed off Raymond Dart’s old theory of “osteodontokeratic technology” amongst Australopithecines [“South Apes”] – bone tools, in English. Supposedly the many animal bones found with the South Apes were tools, implying they were a lot smarter than chimps. All the apparent techno-violence implied the South Apes were “killer apes” as one popularist, Robert Ardrey, put it back in the 50s and 60s. That’s the inspiration for the homs wielding bones at the start of “2001: A Space Odyssey”….

Then Brain showed conclusively that all the bones were from predator “middens” including the South Ape bones – they were prey not predators! Since then the South Apes have been dumbed down to about chimp level – Brain did show some intentional modification of bones by later homs, bones used as digging tools by either Paranthropus [Near Man] or early Homo.

In the current news Brain and Francis Thackeray have potentially shown intentional fire use from c. 1.5 Mya, a million years before widely accepted fire use at Zhoukoudian, China. Lots of previous claims for intentional fire in Swartkrans have been shown to be bush-fire traces, but this time the data is good. This bolsters a theory by Bernhard Wood that brain-growth in early Homo was enabled by cooking tubers – there’s those digging bones paying off – as this allowed steady high-level nutrient supply. Perhaps he was right?

Posted at 10:39 am by Adam
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Friday, March 05, 2004
Far Futures I…

One of the most enduring and beloved SF tales is Isaac Asimov’s Foundation Saga – not just the first 3 books [originally serialised in the 1940s], nor the two sequels [Foundation’s Edge (1982), Foundation and Earth (1986)] which explicitly link up Asimov’s Empire stories with his Spacer stories and bring the tale up to its mid-point. Not just his early and pre-Empire novels [Stars Like Dust, Currents of Space, Pebble in the Sky] which set the scene and fill in a rather mysterious history – Foundation begins in 12,069 GE as the Empire is falling. Hence lots of story to tell. Not just the Spacer/Robot novels which link the “Spacers” of his 1949 story “Mother Earth” with his most famous creations, the Law-abiding Robots, the pinnacle of which are the humaniform robots – robots that are essentially human, just made better.
Peripheral to these he also has his Lucky Starr juvenile series, set in the Spacer Galaxy [perhaps], seen from an oppressed Earth’s viewpoint. Also there is his time-travel tale The End of Eternity which involves an infinity of alternative futures manipulated by “Eternity”, an organisation that controls History to keep humans safe, but denys us the Galactic Empire and loses the Galaxy to other intelligences as a result.

Even the Spacers have a prehistory, before interstellar travel, as inhabitants of artificial space colonies, as depicted in Nemesis.

And finally his Prequels to Foundation, which tell Hari Seldon’s story, and themselves inspired [commissioned] sequels by three of SF’s best, Greg Benford, Greg Bear and David Brin.

Here’s a rough timeline by another Asimov fan…


… the Foundation Saga covered so much of the author’s life [1942 – 1992] that it is naturally inconsistent in its internal chronologising. Included in the above ‘line are several novels commissioned by Asimov to expand on the Spacer/Robot stories – something purists might object to. I don’t know. As a Foundation fan the subtle and not-so-subtle aging of the tales adds to their charm. Asimov was sufficiently aware of technical change to imagine advanced display and computing technology even in the late 40s, but he sets their implementation millennia hence – oh well, can’t always get it right. His later explanation of the “hyperspace Jump” as a tachyon conversion/reconversion seems quaint in an era of [theoretically] manipulable wormholes, Brane-worlds and Alcubierre warp drives..

Posted at 12:05 am by Adam
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Friday, February 27, 2004
Kuiper Belt, flexi-screens and Asimo…

Out beyond Neptune, in the general region of Pluto, is a massive second asteroid Belt, known as the Edgeworth-Kuiper Belt. Predicted by astronomers Edgeworth and Kuiper c. 1950, modelled by computers in the 1980s, and first verified by astronomers in 1992, the EK Belt is massive compared to the much sparser Main Belt between Mars and Jupiter. Also the EK Belt is populated by some huge asteroids – Pluto being the largest, and commonly passed off as a planet. Another recent and large denizen of the Belt is 2004 DW…


Another piece of BBC news was on the latest in mass-produced Flexi-screens – organic LCDs thin enough and flexible enough to roll up…


Stephen Baxter, noted British SF writer, has flexi-screens go a step further and become “soft-screens” with built-in computer circuitry. Computing power you can wear as a t-shirt basically. Several possibilities arise – what if the “smart-clothes” can “see” as well as they are seen? They could then re-display what they “see” from any angle, effectively giving the wearer perfect camouflage.

Another SF related tech news-bite is the visit to the UK by Honda’s Asimo…


Asimo – suspiciously sounds like “Asimov” who gave us believeable humaniform Robots – is a dwarf and not a fast walker, but such is the life of a prototype. If a demand exists for such humanoid robots then expect to see Asimo’s descendents almost everywhere in the next few years. As Japan ‘greys’, many expect humanoids to become aged-care attendants en masse, as is made clear in Honda’s various statements on why it has developed Asimo.

But there is more to Asimo than that. I think Asimov mapped out the future of robots quite well – probably resented on Earth as displacers of labouring workers, though that happens now everytime a job goes overseas, but robots will be absolutely vital to labour-starved communities in Space.

Posted at 9:58 pm by Adam
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Wednesday, February 18, 2004
Stellar models…

No I’m not talking about SuperModels, but mathematical modelling of stars. Our Sun is the most solidly modelled star and we probably have a better understanding of its interior than any other astrophysical object other than Earth. Since neutrinos pass from its Core directly and are reasonably accessible to observation we might have a better idea of the Sun’s Core than the Earth’s.

One older model that traces current estimates fairly well is available at Arnold boothroyd’s homepage…


…interesting features are the end of the Main Sequence at ~ 10.9 billion years age, some 5.3 billion [giga-]years from Now. The Sun slowly rises to about 2.3 times its current output, making Mars a nice place to live for about 700 million years because the Sun will keep an even keel for this period as its Core rearranges. Hydrogen burning is finished in the Core, but it continues in a shell around the Core.

Then between 11.6 [7 billion years from Now] and 12.2 gigayears of age it rapidly rises in luminosity and bloats into a Red Giant. This is known as the Red Giant Branch, or RGB. Luminosity will peak at ~ 2350 times current, but thanks to mass-loss in a Super Solar Wind, Earth will be a bit further away and not fired quite so much. Even so it will be very unpleasant long before then.

If the Earth is braked by the Sun into Sun-synchronous orbit then it will be divided into a Light Side hot enough to boil most rocks – about 2000 degrees C – and a Cold Side cold enough to freeze most gases. In between will be a Twilight Land perhaps warm and wet enough to sustain a Ribbon of Sea around the planet. A strange, eldritch realm, reminiscent of Brian Lumley’s Starside world of Vampires.

As the Sun bloats the Core collapses slowly and heats up, eventually hitting the ignition temperature of helium, causing the Core to explode in the Helium Flash. Sounds dramatic but most of the energy goes into heaving the Core into a new configuration that burns evenly (about 44 times brighter than Now) for about 100 million years.

Then the Sun will race rapidly up the Asymptotic Giant Branch (AGB) once helium Core burning finishes, then suffer several spasms of mass loss as mini Helium flashes crash across the Core, eventually shrinking the Sun into a 0.55 Solar-mass White Dwarf with a pretty planetary Nebula. At an age of 12.4 billion years the Sun will be a cooling White Dwarf that will slowly radiated away its heat surplus, its Core solidifying into crystalline carbon – Diamond.

A curious Future for our Sun and Earth, if we do nothing…
Posted at 12:52 pm by Adam
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Sunday, February 15, 2004
Plasma Magnet

A Cool Concept from NIAC…


…related to the Mini-Magnetosphere Plasma-Propulsion [cleverly named M2P2] concept this has real potential to change the way we think about interplanetary propulsion. But the M2P2 concept also allows shielding against cosmic rays without heavy physical barriers against GeV particles.


A couple of hundred kilowatts and conceivably the system could allow space colonies with much, much lower masses than the old concepts. A typical 10,000 person colony masses 6,000,000 tons with passive shielding, but with a plasma shield the mass drops to a mere 50,000 tons or so. A 120-fold improvement in mass allocation per person. That brings down the cost to something semi-affordable once Space Elevators are shipping to GEO at ~ $220/kg. I’d guessitimate ~ $20-50 billion for a Space Colony – the GEO cost is ~ $11 billion. That’s $2-5 million per person, which would make it a retirement option for the upper classes [copyrighted concept.]

At the same time a system with a few kilonewtons thrust could allow mobile colonies able to cruise between the planets over a few years. A 50,000 ton colony with 5 kilonewtons thrust could leave L4/5 for Mars and dock with Deimos after ~ 990 days [total dV ~ 8560 m/s.] Smaller vehicles would be a lot quicker, but a colony doesn’t need to be quick.
Posted at 10:48 pm by Adam
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Sunday, February 08, 2004
Extrasolar Planets I

Some excellent web-sites for images of hypothetical and not-so hypothetical planets around other stars…


…a cool German site with lots of good background and cool images of the known exoplanets.

Equally cool, but wordier is SolStation…


…it has lots of information on nearby stars and well-known stars [of the bright and gassy variety, not Hollywood] as well as the known exoplanets.

More on both later, plus some more academic sites from the planet searchers themselves.
Posted at 10:36 pm by Adam
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Friday, February 06, 2004
Gliese 673

Most stars are catalogue references, since the most numerous are the faintest and invisible to the human eye. Hence they’re known only to astronomers in their catalogs of stars.


This particular link is to the Internet Stellar Database which is a hobby-site by an astro-nut like myself. This particular star was the source of a very powerful radio signal detected by Australian radio-astronomers in 1990. Sadly it was never confirmed – it stopped before other radio telescopes could focus on it so no one can say if the signal truly came from ETs trying to call us.

However since HD 157881/ Gl 673 is a mere 25 light-years away the timing is suspicious. 50 years is the minimum time for a returned signal from HD157881 and back in 1940, the time of the Battle of Britain, powerful radars were being used almost for the first time. Conceivably these signals made it across the light-years to be detected and beamed back at us as a prelude to Contact – hearing your own signal is sure to get attention according to Ron Bracewell, an Australian SETI guru.

So what is Gl673 like? It’s cooler than our Sun, a K7 dwarf, so its a bit over 4000 K. Its visual luminosity is 1/20th of the Sun, but being so cool quite a bit more of its output is invisible infra-red. Hence using (conflicting) bolometric corrections from a couple of sources I get a luminosity between 14 and 11 % of the Sun. Based on the mass-luminosity relation of Iben that’s a stellar mass of ~ 0.61 solar masses.

At Earth levels of insolation a planet is a mere 0.374 – 0.331 AU from Gl673, and on the fringes of being tidally locked to the star. However that’s not a biospheric death sentence since we now know from advanced climate modelling that tidally locked planets with atmospheres transfer heat sufficient to even things out – the extremes are about 323 K Sunside and 223 K Starside, with “nice” temperatures in between.

Also since the UV in the star’s light is a lot less a methane-induced greenhouse can keep it warm out to quite high orbital radii. Oxygen rich atmospheres would preclude methane unless the biosphere resupplies it.

Less UV might mean less oxygen, since higher energy photons are used on Earth for aerobic photosynthesis – but that’s speculation. Maybe relatively brighter stellar flares help energise the biosphere? Or different biochemicals can do the same trick?

Gl 673 does have a higher metallicity than the Sun, so based on Marcy & Butler’s recent figures that gives a ~ 25% chance of Jovian planets. Since most stars form with dust disks [precursors to rocky planets] terrestrial planets are likely. Based on such considerations my gut feeling is that Gl 673 really might have intelligent Life that was trying to catch our attention in 1990…
Posted at 12:00 am by Adam
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Thursday, February 05, 2004
Getting around the planets

We’ve all been told that getting between the planets is going to be revolutionised by ion-drives and while that is true for space-probes ion-drives currently accelerate far too slow for manned missions. Smart-1, Deep Space-1, Dawn and even JIMO take years to spiral out to their targets. This is because they are energy limited to milligee and microgee accelerations, powering their ion-thrusters with mere kilowatts of power.

A lot of interest has surrounded the new VASIMR plasma rocket for manned missions, but it too is power-limited. In one scenario a VASIMR powered by 12 megawatts from three reactors would allow a mothership to drop-off a re-entry vehicle at Mars after 115 days, then deccelerate into Mars orbit after 243 days. Pumped up to 200 megawatts and it would reach Mars in a mere 39 days – if the mass of the power source can be kept down. Currently a kilowatt per kilogram is unachieved, but near-term, so a 200 megawatt reactor would still mass 200 tons, which is too heavy.

Newer reactor designs and break-throughs like fusion-power will transform the mass-energy ratio and allow fast ion/plasma-drive space vehicles, capable of flights to Mars in a couple of months and trips to Jupiter in a year. One possible design is George Miley’s fusion-ion vehicle described here [1.92 meg PDF file]…


A NASA information page covers an earlier version of Miley’s design here…


George Miley advocates a radically different fusion reactor design called inertial electrostatic confinement fusion (IEC) which will have a higher power-mass ratio than regular fusion reactors. Here’s a brief look at IEC from American Scientist…


Fusion powered ion-drives will open up the Solar System, but be inadequate for interstellar travel. Many researchers in SETI [Search for Extraterrestrial Intelligence] want interstellar travel to be impossible – or at least utterly impractical – because if it isn’t then they face the FERMI PARADOX. I’ll discuss that idea later, but here’s a very recent discussion of interstellar travel concepts currently under research…


Surprisingly the simplest way to the stars seems to be without rockets – instead a ship rides a beam of micro-sails fired off rapidly by an intense laser. The sails are ionised by lasers as they approach the ship and the resulting plasma pushes against the ship’s magnetic field.

Posted at 9:27 am by Adam
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Tuesday, February 03, 2004
Vermin of the Skies

Asteroids tend to be discovered by accident in long-exposure photography – hence the nickname – but they are little worlds in their own right. Ceres is the largest, heaviest and quite interesting because it appears to have an icy crust, bright polar caps and perhaps a thin occasional atmosphere. At 960 km across it’s fairly hefty. Recent measurements of its density show that it is essentially a big ball of compacted mud. And water is one of the most precious things in space.

Second to Ceres is Pallas, which has also had its density measured and spectroscopically [in infra-red] it is very similar to another large asteroid, Vesta. Both are denser than basaltic rock, hence they probably have dense cores of metal, and apparently have suffered vulcanism. For an asteroid this is quite a surprise since they’re not expected to have a lot of internal radioactive heat to melt rock and differentiate lighter rocks from heavier metals. Current theory suggests that the intense magnetic fields of the early Sun caused induction heating – like an electric furnace – and melted their interiors. Since then both asteroids have been battered by lesser asteroids colliding with them. Vesta has an immense crater near its north pole, which has blasted multi-kilometre wide chucks into space. These form an asteroid family of lesser bodies that are related to Vesta, as determined by their orbits and spectra.

NASA, hopefully, will launch an ion-propelled probe to visit Ceres and Vesta in 2006…


Dawn will slowly spiral out to Vesta over 4 years, orbit for some months, then spiral out to Ceres to arrive in c. 2014 for a year of orbital observations. Beyond Ceres, NASA is hoping to cheak out lesser asteroids further out.
Posted at 1:38 pm by Adam
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Monday, February 02, 2004
Ascension of Isaiah…

In the Gospel of Peter Jesus is depicted as rising from the tomb supported/sustained like an Emperor by two attendant angels – behind them is a great cruciform procession, a symbol of the righteous dead rising with Jesus in his triumph over Death.


Here’s the verses in question from the link above…

10 Now when these soldiers saw that, they woke up the centurion and the elders (for they also were there keeping watch). 2 While they were yet telling them the things which they had seen, they saw three men come out of the tomb, two of them sustaining the other one, and a cross following after them. 3 The heads of the two they saw had heads that reached up to heaven, but the head of him that was led by them wen beyond heaven. 4 And they heard a voice out of the heavens saying, “Have you preached unto them that sleep?” 5 The answer that was heard from the cross was, “Yes!”
A very early text, which some call a pastiche but others consider a unified text, is the Ascension of Isaiah. It is a very early text, probably c. 66-70 AD. An interesting commentary can be found here…


And the text is here…


And the parallel in the Ascension of Isaiah…

14. And the god of that world will stretch forth his hand against the Son, and they will crucify Him on a tree, and will slay Him not knowing who He is.

15. And thus His descent, as you will see, will be hidden even from the heavens, so that it will not be known who He is.

16. And when He hath plundered the angel of death, He will ascend on the third day, [and he will remain in that world five hundred and forty-five days].

17. And then many of the righteous will ascend with Him, whose spirits do not receive their garments till the Lord Christ ascend and they ascend with Him.

18. Then indeed they will receive their [garments and] thrones and crowns, when He has ascended into the seventh heaven.”

Hence both these ancient Christian texts consider the Resurrection of Jesus to have included the resurrection of the Righteous as well. A very curious belief indeed, dramatised in Dante Aligheri’s Inferno as memories of the “harrowing of Hell” and spoken in the Apostle’s Creed as “he descended into Hell”.

Posted at 12:52 pm by Adam
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