In Response To: My usual obsession (Lekgolo) (scarab)
: I saw this 16 minute video on Thorium reactors which is utterly cool in its
: own right and then it got me thinking of Lekgolo again and my obsession
: with their biology. (In brief: I think that they are nuclear powered,
: silicon based lifeforms)
: (It may be best if you read this post in its entirety then investigate the
: links.)
: Naturally Occurring, Water Moderated, Nuclear Reactors
: When lookig at other LFTR links I found all these sites: (All on the same
: subject, I don't think that you need to read every one to catch the drift
: of them, but if you find yourself fascinated...)
:
: Curtin University Slow(ish) to load but worth a 10 second wait
: NATURAL NUCLEAR REACTORS (OKLO) - A bit new ageish?
: The Oklo Natural Nuclear Reactor
: Scientific American
: Natural nuclear fission reactor - Wikipedia
:
: How large were these reactors? They were small, smaller than a person. See
: the last pic on this page . The reactor is the yellow patch of rock where
: that guy's hand is.
: The links refer to naturally occurring nuclear reactors, discovered in Oklo
: in Gabon in Africa, that existed 2 billion years ago. Their existence
: depended on the higher proportion of fissile Uranium isotopes found 2
: billion years ago (which have since decayed) and free oxygen (due to life
: and photosynthesis). So such reactors have a limited time window in which
: they can exist.
: But if you watch the video at my very first link you could imagine a planet
: with a different mineral composition than Earth. Maybe there were more
: radioactives, maybe lots of fluoride salts - then maybe there could be
: natural molten salt reactors.
: To get fission you need to concentrate your fissile isotopes and to get
: controlled fission you need a moderator (something that slows down
: neutrons via collisions with the atoms of the moderator) and a feedback
: mechanism to keep the reactor critical.
:
: Sub-critical: reaction stops.
: Super-critical: boom!
: Critical is the mother bear state. :-)
:
: The Oklo reactors used water as a moderator and when the reaction became
: super-critical then the heat evaporated the water and drove it out of the
: reactor and therefore stopped the reaction. The entire rector acted like a
: geyser - it was active for about 30 minutes at a time then had a 2hr 30
: min cool down period. (This cycle lasted for over 1 million years)
: Molten salt reactors are self controlling because the salt expands when too
: hot and therefore dilutes the fissile material and when it cools it
: shrinks and concentrates the fissile material.
: Te: The Lekgolo Homeworld
: Imagine if silicon based life evolved on Te. What kinds of ecosystems would
: develop? Energy webs are a fundamental aspect of ecosystems - what are the
: sources of energy? and how does energy flow through the system? (What are
: the primary producers? and what eats what?) Primary producers tap into
: some non-organic energy source and grow in great abundance. Everything
: else eats them or eats something that eats something that ate them.
: (Gratuitous lecture on ecology, photosynthesis, and chemotrophs omitted for
: brevity)
: What Energy Sources Would Be Available For Underground Life On Te?
: I can think of three main categories:
: Chemical - like wot we see around mid-oceanic vents
: Geothermal - extracting energy from the movement of heat down thermal
: gradients
: Nuclear Fission - extracting energy (thermal or from ionizing radiation)
:
: I think that any organism would need to convert these energy sources into
: chemical energy - create energetic chemicals and get work from these
: chemicals by converting high energy chemicals into low energy chemicals. I
: will discuss how you can get chemical energy from the three sources of
: energy mentioned above.
: 1 Chemical
: I'm not so interested in the first category because its too normal for
: biology. Read a text book or Google, its all out there for you. :-)
: 2 Geothermal (extracting heat from thermal gradients)
: But extracting energy from heat gradients seems more fun and it might apply
: to Lekgolo. The reason that it might apply is that you need to have a
: large enough difference in temperature to get significant heat flow. This
: means that you need large or very long organisms. If you have natural salt
: reactors then you could have localized heat sources and it might be viable
: to have elongated organisms or collections of elongated organisms that
: could conduct heat away from the reactors and extract chemical energy from
: this. They could do this by using a thermoelectric effect .
: Imagine a collection of cooperating individual organisms - some envelop the
: reactor and grow asbestos like, insulating, fibers to lock in the
: reactor's heat (so that all of it is available for use) - others form long
: chains, comprised of many elongated individuals, that conduct the heat
: away and use the thermoelectric effect to extract chemical energy from the
: heat. The conductor organisms could themselves be sheathed by insulating
: individuals until they reach a cold region.
: The terminal individuals exchange heat for chemical energy and share this
: with their insulating allies.
: So we have a system of cooperating individuals. These need not be Lekgolo and
: they need not be all of one species - but we have many different organisms
: on this world that can do this trick. Lekgolo could be a collection of
: cooperating species all working together for the common good.
: This cooperative behavior could be one reason why Lekgolo are colonial
: organisms, comprised of many cooperating individuals.
: Are their any examples of this on Earth?
:
: Corals
: Corals are colonial organisms that host photosynthetic algae within their
: cells. The coral cells provide CO2 to the algae. The algae provide oxygen
: and carbohydrates to the corals. The corals will consume the algal cells
: on occasion.
: Hydrothermal Vent Comunities
: Cold Seep Comunities
: The Human Body
: There are 10 times more bacterial cells in and around our bodies than there
: are human cells. We rely on them to digest our food, to synthesize
: vitamins and to protect us from harmful organisms.
: The human is the only thinking part of this community. Lekgolo may have an
: analogous arrangement.
:
: But lets get back to geothermal energy. How does the geothermal/heat-gradient
: idea apply to Hunters?
: Imagine that Hunters have a heat source at their core, could they extract
: energy from it? Some worms could generate heat, some could insulate, and
: some could conduct it to a cold spot.
: But the system would need a radiator. The spines could work but they have a
: low surface area. Radiators need a large surface area. And the radiator
: needs to be away from the main body of the Hunter.
: Is there anything that fits the bill on a Hunter?
: Of course there is: its the shield!
: Wouldn't it be cool if the physical appearance and behavior of Hunters was a
: direct consequence of their biology? Those things wouldn't be arbitrary.
: Lets move on to the 3rd source of energy: Nuclear.
: 3 Nuclear Fision (extracting chemical energy from)
: We need a way to extract chemical energy from nuclear processes. We have
: already looked at the thermoelectric effect, is there another way?
: How about extracting energy from ionizing radiation?
: This isn't really feasible for DNA/RNA carbon based organisms because
: ionizing radiation damages DNA. That may not be a problem for a silicon
: based life-form because they don't use DNA. :-)
: There are many sources and types of ionizing radiation. For example Alpha
: decay and Beta decay . Also, high energy neutrons can knock protons out
: of atoms and those high energy, charged, protons can be an ionization
: source. Wherever you have reactors and fissile material and their products
: then you have sources of ionizing radiation.
: How could an organism extract energy from ionizing radiation?
: Well ionized free radicals are very energetic in their own right you just
: need some way to harness that energy.
: In addition we could use an analogy with photosynthesis. In photosynthesis an
: electron is transported across a cell membrane to establish an electric
: field gradient across the membrane. The membrane has protein complexes
: embedded in it that allow protons to cross the membrane. The proton
: transport is driven by the electric gradient and ATP is synthesized by
: extracting energy from the proton transport.
:
: moving electrons across membranes
: Creating ATP via protons crossing membranes (ATP synthase)
:
: If an organism could transport high energy electrons generated by ionizing
: radiation across an insulating barier then it could use the electric
: gradient produced to generate high energy chemicals that it could use for
: its metabolism.
: 3 Nuclear Fission (generating)
: The problem with naturally occurring fissile material is that it is fissile.
: :-) It decays and over evolutionary timescales it becomes rare. Nuclear
: based silicon lifeforms could develop and evolve but, over billions of
: years, any naturally occurring reactors would cool down and general
: background radiation levels would drop.
: Organisms would need to develop their own reactors.
: This doesn't sound too hard to do. You need to concentrate a fissile
: material, supply a moderator, and control the reaction.
: Organisms are good at extracting substances from the environment and
: concentrating them. This should be a piece of cake for our hypothetical Te
: lifeforms.
: They could use water as a moderator and therefore be fairly cool reactors or
: they could be molten salt based and therefore fairly hot. I like the idea
: of Hunters being orange-hot lava monsters. :-)
: As for controlling the reaction: we have seen that this can be done with
: simple physics. We have examples of naturally occurring reactors using
: boiling water and the LFTR reactors mentioned in my first link use
: expanding salt and work at room pressure.
: How does this apply to Lekgolo?
: Imagine that Lekgolo ancestors started off using natural Oklo style reactors.
: Then imagine that over time 'bacteria' on Te could concentrate Uranium and
: do a better job of moderating the reaction so that the reactors were at
: critical longer than natural reactors.
: Imagine that Lekgolo ancestors lived in association with these 'bacteria'.
: The Lekgolo cultivate the bacteria, transport bacterial reactors to good
: locations and bring fissile material to the reactors. Some Lekgolo
: ancestors could become mobile and carry their reactors around with them.
: The bacteria would act like our intestinal flora.
: Over billions of years, as levels of fissile material drops - reactor
: colonies could start collecting fertile material for example: Thorium to
: create breeder reactors and therefore avoid the problems caused by the
: loss of fast decay fissiles.
: Water Or Salt Moderated Reactors?
: The problem with water moderated reactors is that they depend on life
: (photosynthesis) to create free oxygen - we need oxidizing conditions to
: make Uranium dissolve in water so that it can be transported and therefore
: concentrated into reactors.
: I don't want Te's silicon based lifeforms to depend on surface living
: photosynthesizers. Its just my prejudice and my preference.
: I don't know what mechanism would concentrate Uranium without water but we do
: know that living systems play a major role in concentrating materials.
: What if Te initially had higher general background radiation levels and
: that early Te bacteria just lived from energy extracted from ionizing
: radiation. They had an easy life because ionizing radiation was
: everywhere. They just need to ingest radiating emitters from their medium.
: Lava consists of course crystals in a liquid. The liquid flows through the
: gaps between grains. I will call this the interstitial fluid or the
: medium.
: Some of our early Te bacteria could swim through this medium seeking out
: fissile rich areas. Over time as fissile materials become more rare then
: large numbers of motile bacteria could concentrate Uranium into small
: areas to make living reactors. I imagine that these would be clumps of
: bacterial mass somewhat like stromatolites . Or maybe they just clump in
: one spot, say in crevices, and extract fissile material from the flow of
: the interstitial fluid.
: Some bacterial colonies could stay in good hotspots and shed spores that seek
: out new hot spots. Some colonies could breakup if conditions get bad and
: then move on to better areas. They could become something like Slime
: Molds .
: Interestingly some slime molds farm the bacteria that they live on. So its
: not just humans and ants that farm their food. :-)
: Getting back to Lekgolo
: Our Lekgolo ancestors could have formed around, salt moderated, living
: bacterial reactors as opposed to, water moderated, Oklo style reactors.
: Lekgolo could be late stage organisms
: Lekgolo would be the latest products of a long evolutionary history. If an
: organism can carry its own reactor around with it then it can explore new
: territories where fissile material is scarce. They can get their nuclear
: fuel by eating other, nuclear based, organisms. They would be at the top
: of the silicon life based food chain.
: Lekgolo can live on the surface. They may not even be able to live in lava
: themselves, or maybe their young do, who knows.
: Te may have developed carbon based life on its surface and Lekgolo could be
: used to coexisting with carbon based life and they are obviously tolerant
: of free oxygen atmospheres but they probably don't breathe oxygen
: themselves. The worms near the centers of colonies and in the Hunter limbs
: do not have easy access to oxygen. Also, nuclear processes are millions of
: times more energetic than chemical processes. They can afford to
: synthesize very high energy chemical products and not have to worry about
: extracting the last ounce of energy from them.
: Maybe silicon and carbon based life has coexisted for so long that Lekgolo
: use carbon from symbionts as another moderator.
: Other aspects of their biology
: Hunters don't tend to run around a lot until a threat turns up. Maybe their
: reactor is a pulse reactor like the Oklo reactors. Maybe they generate
: their analog of fats or sugars whilst the reactor is critical and then
: they 'burn' this fuel when the reactor is sub-critical. I don't know if
: they literally burn it using oxygen but I doubt it as the worms in the
: interior parts of the colony do not have easy access to the atmosphere.
: How Does My Proposed Biology Determine Lekgolo/Hunter Form And Behavior?
:
: It explains why they are colonial organisms
: It suggests that there could be a minimum size limit for Lekgolo colonies
: Its possible that a Hunter is the smallest possible collection of Lekgolo
: worms that can achieve criticality (but see Hunter pairs below).
: Individual worms may be able to venture from the colony for short periods
: of time but they rely on the colony for their 'food' and warmth and
: intellect.
: It explains their armor form and function.
: The armor could allow a single single Hunter to be as small as it is because
: the armor could act as an insulator (it could have a foamed metal core)
: and as a moderator (carbon lining) whenever the Lekgolo's reactor is
: critical.
: And the Hunters may have a shield instead of just thick armor because the
: shield can act as a radiator.
: It gives another reason why Hunters travel as pairs
: Maybe at night the two colonies huddle together and start a joined reactor to
: cook up the food that they need for the next day. Maybe the two
: shield-radiators glow cherry red when the reactor is critical.
: You wouldn't want to stand next to this neutron source when it is active. :-)
: Maybe this explains the pair bond. The worms form a collective intelligence
: when it proximity. The two collectives merge to some degree when the two
: colonies merge at night. They may dream together.
: Maybe a small number of worms move between colonies keeping a bond alive in a
: way that we singletons just can't understand.
:
Nicely done! Loved it!
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