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Ken Fabian

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Posts posted by Ken Fabian

  1. 4 hours ago, J.C.MacSwell said:

    I thought a significant part of the sea level rise was due to water expansion with increased temperature. Not sure where I read it but I'll look...

    Wiki on Sea level rise has this 

    Between 1993 and 2018, thermal expansion of the oceans contributed 42% to sea level rise; the melting of temperate glaciers, 21%; Greenland, 15%; and Antarctica, 8%.[3]:1576 Climate scientists expect the rate to further accelerate during the 21st century."

    ( mentions approx 3" rise between 1993 and 2017)

    Currently sea level rise from thermal expansion is greater than that from ice sheet/glacier sources. However my understanding is the proportion from melting ice is expected to rise significantly. Between now and 2100 the rate of sea level rise is not much different between low emissions scenarios and high - mostly thermal expansion - but slows with low and accelerates due to ice sheet contributions with high emissions, with much higher rates of rise over the subsequent couple of centuries. There is also potential for ice sheet collapse that could result in surges in ice loss and sea level rise - and these resist reliable prediction.

  2. It is all a bit too speculative or something for my liking. That some planets might be more likely than Earth for life - and for complex life - to develop seems a reasonable proposition. Knowing exactly what conditions those might be is going to be difficult, but even the assumption of milder, warmer, less extremes being "better" looks like overreaching.

    I don't think we know what "better" is. Could not extreme conditions and variability be more - not less - significant to evolution?

  3. Not knowing anything about it I thought fish  probably wouldn't have bone density problems in zero gee - but I was wrong. From studying fish raised on the ISS -


    ..investigators found increased volume and activity of osteoclasts and significant reduction of bone mineral density in the fish aboard the station. Using electron microscopes, investigators also observed abnormalities in osteoclast mitochondria.

    Osteoclasts are a type of bone cell that triggers bone breakdown and re-absorption - and are essential to maintaining, repairing and remodeling bone. Microgravity appears to inappropriately activate osteoclasts.

    I don't think there is going to be much difference between cetaceans and humans in how bones grow; many human bones aren't weight bearing and are equally "buoyed up" within the human body, as much as cetaceans would be. Weight bearing bones in the absence of weight can make do with the compressions generated by exercise but those osteoclast cells affect bone density in mice and human and almost certainly will in cetaceans as well.

  4. Lots of subjects of scientific inquiry won't conflict with a lot of versions of religious faith. A sense of wonder that has religious aspect has been a significant motivation for scientific inquiry, often without leading to false conclusions despite the overlap. But there are those who's religious beliefs lead them to attempt to disprove the science that appears to conflict with their faith, sometimes honestly applying scientific methodology but often not. Those may well put their conclusion first and will dismiss the validity of science outright should that conflict look unresolvable. It should not be necessary to know what the author of scientific papers has for personal beliefs in order to judge the validity of what they publish.

  5. On 9/12/2020 at 6:44 AM, Hello2 said:

    What about the question: Can musclepower be used to improve energy-generation?



    I'm not sure tree climbing machinery is a major user of energy. Using bicycles more conventionally isn't so much significant for direct energy generation as significant for avoided generation elsewhere, in this case motor vehicle energy use. It is genuinely significant in that regard. Tends to be good for the people using them, so long as car drivers don't run over them.

    On 9/13/2020 at 2:30 AM, drumbo said:

    Fossil are a dream, they are perfect. God must have put it here for us to use, how else can you explain its perfection?

    Ancient dead stuff from the deep bowels of the Earth, that burns with a foul brimstone stench - and with poisonous fumes, that adds  about 100x more heat to the world at large when mixed in atmosphere than the "useful" energy produced. I would argue that is making the world more Hellish and the idea that we got it all as a gift from God - that it is a perfect and absolute Good, and comes with no Catch - is so wrong that it is hard to comprehend how religious leaders could fall for it. Temptation from below, not manna from above IMO.

    Rather than "low" in toxic waste, it makes vast amounts of poisonous fly ash besides the CO2 that is our single biggest toxic waste stream, exceeding all other waste (5 times over). "Luckily" it is invisible and can be diluted in atmosphere... where it can go on to add that extra heat. According to an odd fellow with burning eyes and growths that looked like horns growing out of his head fossil fuels are so "perfect" they can solve most human suffering without any need for humans to be "good"; there will be so much wealth left over from Greed applied ruthlessly to an abundance of Fossil Fuels that enough trickles down that all humans are raised up. Well, it can if people weren't... so greedy. Can be used for great engines of war, for smiting enemies too.

    A catch? Well, sure it adds some heat to the world, but not all the navvies with all the shovels in the world could dig up enough coal to cause measurable warming! Oh, you can also use it to make machines that can dig ten thousand shovel's worth at a go. No catch, Drumbo?

  6. I expect complex engineering projects are not even possible, let alone done better by individual engineers. Teams are essential. Selection and management of that team will be crucial.

    As an aside I think the gratuitous derision of camels, as being a "badly designed horse" makes for a good joke - for horse lovers. Meanwhile camels are superior (better "designed") to horses - for wild survival and as a beast of burden - in many circumstances.

  7. On 9/11/2020 at 10:36 AM, ScienceNostalgia101 said:

    would this double as a way to make forest fires less severe, by the fact that there are fewer trees available, per square kilometre, to catch fire in the first place?

    It is not as simple as less trees equals less fire risk; mostly it is the grass and undergrowth and leaf litter that burns most readily in forest fires, not usually trees. Fires are extreme when forest canopy (trees) burns - and that is more likely when the intensity of lower level fires is enough to carry the fire to tree tops. Eliminating "ladders" of fuel from ground to canopies is often a priority for fire hazard reduction.

    Taking out trees usually results in an increase in fuel, from the treetops - the branches and leaves that are not usually harvested - as well as increased growth of ground vegetation. Dense forest canopies can result in less ground level fuel and fire risk, depending on forest type. Local conditions vary greatly.

    Hypothetically the tree tops could be harvested too, but boilers made to burn wood may not be suitable for burning leafy material, which may be better done through gasification (heating without burning, to produce flammable gases). They present harvesting problems compared to logs; little or no existing equipment or infrastructure compared to burning sawn or split wood or chips. And if there is insufficient demand for that kind of fuel - or the costs are too high - then subsidy and regulation would be needed to make it happen. Relying on forced labor may not be the best way to do things that are hard - it usually isn't efficient.

    As a fuel that can replace large amounts of coal burning? I'm not sure it cannot be done at large enough scale to be a large part of our energy supply; there are better (competing) options as well as competing uses for wood - and the question as posed represents a transition, from dense forest to thinned, that stops when the intended outcome is reached. Permanently displacing fossil fuel use requires trees to regrow.

  8. On 9/17/2020 at 5:30 AM, joigus said:

    I saw a cartoon the other day suggesting that it's to do with science and scientists sounding arrogant in the ears of big swathes of the public. I'm not so sure about that, but there seems to be a communication gap.

    People in positions of trust and responsibility in the US (and Australia where opinion like Trump's also runs deep through conservative politics, conservative commentary) got the same science based reports on climate as everyone else; they are not rejecting it because some scientists seemed arrogant or said things that were exaggerated or wrong, they are rejecting it because it is almost certainly true and they don't want it to be true - because being true demands an appropriate response. These are people in high places who mostly know better - who are expected and relied on to read the reports that governments asked and paid for and look past the arrogance of scientists who won't change the conclusions to suit the political leanings of the those in charge, who should be pleased at that obstinacy in refusing to alter "facts". But the lack of immediacy and of readily observable change puts election cycles and whole political careers between absence of appropriate action and bad climate outcomes. We are just getting some of those but even those are not necessarily clear and obvious within the variability of year to year weather. All making Doubt, Deny, Delay look like something that can be (and has been) done successfully.

    I think the ordinary voter/citizen has been taking their lead from and being taken in by people they trust - but not so much of that is from direct communications by scientists. It is science as filtered and reported in mainstream media, with inexpert commentary overwhelming the kernel of content. Our leadership - political and business - has learned or perhaps always known that popular opinion about what is true and not true has more to do with persistent emotive messaging than science.

    Large parts of the mainstream media that are the principle way people know about global warming are partisan political players in their own right as well as businesses that use energy and don't want to pay higher prices for low emissions alternatives, pay taxes and don't want to pay taxes no matter how essential to the nation they profess to love, who don't want regulation, just because. Commercial "news" media's business model is in influencing the choices people make for money, on behalf of other businesses mostly,  businesses that also don't like higher priced power or taxes or emissions regulation either, who may withdraw their business if the editorial policy appears to support things they don't like, like strong action on emissions.

    The choices business operators make are not so much based on what the scientists say will happen over the long term as in how they think it will affect their bottom line in the short term - by the criteria they use it is not even an option to put what scientists say ahead of those; collectively they can use Lobbying, PR, Advertising, Strategic Donating, Post Political Payoffs, Tactical Lawfare, Tankthink to influence public opinion and government policy. Conservative, pro-business politicians who don't pay attention to what captains of industry and business groups say they want get replaced.

  9. It seems much more likely there is an unknown non-biological process making Phosphine than unknown biological processes. But news programs I've seen are hyping the "could be life" story - some with inclusion of appropriate skepticism but mostly not.

  10. On 9/5/2020 at 1:55 AM, MigL said:

    Think about little towns that spring up when a mine opens up in Northern Canada; unless the exploitation is done remotely, people will need to be, and live, there.

    Such settlements in wilderness have no expectation of becoming self sufficient. They import almost everything (apart from air and water) from the greater Canadian and global economy and don't even directly use the minerals they mine. Were that greater economy to vanish or be out of reach they would be in serious trouble, even with foreknowledge and prepperation; an ability to survive, maybe, because there are natural, if limited, food resources and ancient experience to draw on. Sustaining advanced technology and a lifestyle dependent on it? A lot harder. Such outposts can be steps on the way to self sufficient colonisation but are insufficient in themselves. They need stuff to sell to that greater economy.

    Motivations do matter and I don't think making a "Planet B" for backup is a viable one; they need broad ranging commercial viability or else such colonies will, like mining outposts in wilderness, run down when the saleable resource runs out. I think "Planet B" thinking might be a longer term contingency consideration for any greater Earth (meteor) Defense type projects, the way it enters the thinking of military forces with deep bunkers - tacked on to a broader motivation that has substance - but I cannot see it being a primary objective. Elsewise we are talking about living in space being easy because we have achieved such advanced tech and wealth that living in space is easy, like jumping in the campervan for a road trip because we can, with no requirement to pay our way - in which case I wouldn't want to be stuck to Mars or any other colony planet. Visit maybe. We are way, way, way short of that.



  11. 11 hours ago, Airbrush said:

    I am not suggesting generational craft.  Remember what Stephen Hawking said, that humanity has about 100 more years before our extinction.  So how do you want to spend the next 100 years?  Terraforming Mars, building Terminator robots, or exploring the solar system?  People going to other stars seems farther and farther away than ever.  Even sending high-speed probes to the nearest stars seems less likely than just being content to view evidence of life on other planets in the time we have left.



    I don't think Stephen Hawking was ever a reliable source on how long humanity has left on Earth, no matter his brilliance with respect to black holes and cosmology. I think the reality of moving to space is not anywhere even close to being a viable option - and without a healthy wealthy Earth economy, not likely to ever be one. Failing to go all out to fix our problems here will ensure failure to establish a reliable, colonial foothold in space; space colonisation is not an alternative to Earth, it depends absolutely on Earth. If it achieves true self sufficiency, that will be an emergent outcome of success as an enduring part of Earth's greater economy.

    What I think with respect to our looming doom is we face the prospect of our civilisation - such as it is - failing us in the face of cumulative problems. Good governance looks thin on the ground to me - and large elements fiercely resists deep, long running foresight and planning.

    Any collapse of what we see as civilisation won't be the end of humanity by any means, but it likely will put all grand space dreams on hold and make getting back to the wealth and prosperity we now enjoy much harder in any distant future - and what we have is IMO probably unsustainable and overly a product of and dependent on resource over-exploitation in the present at the cost of future resource availability. I am not sure that unrealistic optimism about space and abundant space resources helps with keeping our eyes on this road, hands on this wheel.

    I am not optimistic either way - because I think it wasn't planning and foresight that got us the civilisation we have here on Earth but for getting space colonies on a sustainable footing the minimum population and economy and infrastructure needs to be very large to be able to reach reliable self sufficiency; self sufficiency in space will be very hard to achieve without those natural ecosystems to do so much stuff we depend and thrive on for free.


    7 hours ago, MigL said:

    How do you fix the problem of too many people, without giving them another place to live ?

    I don't think space - even being more optimistic even than most optimists - will ever offer mass migration opportunities; mostly the idea seems to be a smallish number get to colonise space, to go on (we hope) to survive and thrive there and Earth's population gets to survive or not (we hope not) as the case may be. We are suppose to be vicariously comforted by this - enough to not resent paying for it. I remain unconvinced that this "some will survive" motivation can be sufficient to support the scales of construction and investment a viable space colonisation program needs. And we could (real possibility) see significant population decline here on Earth - whether we want it and plan it (still possible, over several generations), or not (possibly catastrophically).

    Interstellar colonising would be much, much   harder than Mars - and I think Mars is still way beyond our capabilities. And Mars would be much harder than Asteroids. And those are still extremely hard. I would probably go for Asteroids and free flying space habitats over planets.

  12. The line between spacecraft and space station/habitat blurs but I can't see even attempting terraforming without an existing full capability of living in artificial space habitats, using asteroid/cometary - ie non-planetary- resources; ie that if we are capable of doing so we will not need to. So terraforming planets is going to be optional.

    I think terraforming lifeless planets will be extremely unlikely and candidates are more likely to be planets with simple life and atmosphere's not too different; ie kill off what is there and supplant it with selected/engineered terrestrial life. And I think that any non-terrestrial life presents both extraordinary opportunities (for study, for potential biological materials and biochemical processes) and extraordinary challenges - cross contamination, disease, parasitism, allergens, poisons. And a very big ethical dilemma. Like I said I think any future humans capable of doing it will be capable of thriving without doing it.

    I think multi-generation spacecraft won't last long enough or be capable of carrying everything they need and will need periodic resupply, refitting, whole rebuilds and - if population grows - new builds. I think that the most achievable kind of interstellar travel will be thousands of generations of hopping from deep space object to deep space object, each time building a local economy and population capable of doing that resupply, refitting, rebuilding; as I've said elsewhere I think nothing short of a large, advanced industrialised economy (and population) can manage the complexity and exacting standards that kind of high tech existence requires. Which view is a key deviation from most of the optimists.

    Whether a clear goal could be sustained that focuses onwards exploration and occupation of DSO's in a target star's direction when DSO's, not planets, are the source of all resources is a question. Indoctrination and social conditioning? I think some serious ethical questions arise when considering some of the possibilities.

    I do think that for enduring safety and security, that space habitats will beat any planets barring Earth. Earth still beats all of them and probably will for millions of years yet.

  13. Studiot - I said -

    12 hours ago, Ken Fabian said:

    I think it would reach pressure and temperature equilibrium and become effectively static. Air movement from convection can occur within the tunnel and changing weather based pressure differences at each end would generate air movements.

    You say -

    8 hours ago, studiot said:

    That cannot possibly be because heat must be transported down the temperature gradient.

    I think pressure would approach equilibrium - and become effectively static, barring transient variations from pressure difference based air movements. And those would average out, even if they don't maintain a perfect equilibrium. With respect to the initial question I think heat is only relevant to pressure at the centre by changing the density of the air column and by that, the weight of the air column.

    Heat flow within a (not insulated) borehole/tunnel? Yes, it must, through conduction, convection and radiation but I think heat profile along the air column would still approach equilibrium over time as well, more slowly for a narrow borehole, more quickly for a large diameter tunnel that allows more convection - which I would expect to be the principal means of heat movement.

    8 hours ago, studiot said:

    You don't need a source of air.

    I said circulation cell and countercurrent flow

    Thinking it further, convection would lead to hot air emerging from tunnel ends - but it would also draw in cooler surface air. Probably not a plume. And I would expect this outcome would still lead to an on-average, depth dependent, temperature equilibrium within the air column.

    With a through to other side tunnel - effectively two tunnels linked at the core - a continuous flow could be generated but off the top of my head (as most of this is) I would expect that the rate of air flow would have to be high enough that maximum air temperature is not reached before crossing through the centre - that it must continue warming (and losing density) on the way back up, in order to maintain the different densities to generate convection flow. 

    For a continuing flow of air outwards you do need a source of colder air that undergoes heating, to generate expansion and lowered density. That has to come from convection within the tunnel or a continuous flow through from one end to the other.

    Some of this must depend on how the initial hypothetical conditions occur - a tunnel appearing magically, fully formed... but if it starts filled with air, is it surface temperature air? That would involve immediate expansion - and flow of air out both ends... until equilibrium. I wouldn't expect strong one way circulation - in one side, heating along the length, to emerge out the other without some significant other factor to get sufficient flow happening.

  14. 15 minutes ago, joigus said:

    the way I see it you must have an enormous reservoir of air to fill in the hole while at the same time have the air compensate for the enormous pressures of the solid/plasma, hot Earth material, that would tend to squeeze the borehole to a mathematical line.

    I think the question is pressure for a lined borehole, a tunnel with walls that hold back the pressure. Or else the question reverts to what is the pressure at Earth's core, sans borehole.

  15. 3 hours ago, studiot said:

    Even without the Earth's rotation a plume of hot air would issue from the ends of the tunnel.

    I don't think that would be true; there is no source of air at the core to support a plume. Nor for flinging air out. I think it would reach pressure and temperature equilibrium and become effectively static. Air movement from convection can occur within the tunnel and changing weather based pressure differences at each end would generate air movements. Given the distances those air movements might be more like sloshing waves along the tunnel, generating their own small transient pressure variations.

  16. If all the ice sheets melt, about 70m of average sea level rise. Counter-intuitively the sea level closest to where the ice loss occurs will drop, with the highest average rise at the greatest distance. The sources would include Greenland and other glacial ice that is not at the poles - but if Antarctica can melt entirely the world will be too warm to support ice sheets or glaciers.

    Predicting the rate of sea level rise - and therefore pin down when a specific location would be inundated - is difficult. We don't know how global warming will progress because we don't know what emissions will be; I would like to believe we can shift to low emissions energy within the next few decades. Then there are big unknowns about how ice sheet disintegration might proceed, with potential for rapid surges in sea level rise from ice sheet collapses. The current rate is above 3mm per year but has been rising - and is expected to keep rising.

  17. I admit this one does have me scratching my head. I wouldn't expect heat to change the pressure once temperature equilibrium is reached but I'm not sure of it. But if you have an imaginary borehole you can imagine it being insulated and then consider the heat separately. On reflection it is likely the heat does matter - by changing the density of the air (or plasma), which changes the weight of the air column.

    My first impressions left me thinking the pressure would be the same as surface air pressure but on reflection it would be SAP plus the pressure from the weight of the air column within the Earth from core to surface - and that weight will vary along that column according to changed gravity gradient - and would be less than a gravity gradient based on a point mass at the core. Maths for that is beyond me.

  18. 6 hours ago, Area54 said:

    An argument from incredulity is never persuasive. I shall ponder whether or not to invest the time to respond in detail. In the meantime, I would ask what makes you feel your intellect is superior to that of von Neumann? Or do you think his proposal for autonomous, self replicating probes was entirely a lighthearted excursion into SF?

    I think in the case of interstellar colonisation - with or without autonomous, self replicating probes - incredulity is entirely appropriate and persuasive. I think the onus is on those doing the proposing to provide extraordinary proof or at least sound reasoning for their extraordinary claims.

  19. Sorry Area54 but your excess credulity that technological progress will overcome all obstacles is naive. We will hit hard limits for what technology is possible, along with economic ones where great things are possible but unaffordable. Some grand space dreams, like Mars colonies, are - I believe - possible, but unaffordable; orders of magnitude too expensive. Hypothesising a high tech solution to every problem isn't going to do it and sometimes throwing more money at a problem just wastes money.

    My remark about what the humans are for if the mission is run and done by AI and robots may have been flippant but any small, artificially raised population will not be in a position to step up, take charge and expect to be able to sustain tech levels that are currently far beyond our global civilisation. They will be dependent on - dependants of - tech they do not understand. Using tech we don't understand may appear quite normal but somewhere there are people who understand it - who design and refine and engineer the tech us users take for granted. It sounds like a recipe for a bunch of artificially raised kids to end up in an intractable bind, where the predicted success and growth - the awesome opportunities - are never achieved.

    The level of living, working expertise needed to sustain a high tech civilisation - including a crucial lot of rare, genuine geniuses -  across thousands of disciplines and subdisciplines is something only large, healthy and wealthy populations - and the economic demand they create - can achieve and support. AI, robotics are another layer of complexity, no matter that from the end user viewpoint it appears to make things easier; the costs and complexities are just elsewhere, ie Earth. 

    Like a library, those supports can aid people but no matter if I have the full specs on how to build nuclear power plants or mining robots I won't be able to do it. Not without the economy and infrastructure and population with skills and experience - and the current setup we have is wobbly; assuming it goes on for millennia and all the time getting more technologically advanced is no more than a correlation; there is nothing inevitable about it.

  20. 1 hour ago, Area54 said:

    If we are envisaging a culture capable of constructing a craft delivering interstellar travel and self-repair over a period of centuries, it is not a stretch to consider an artificial womb for the initial physical development of the embryos and robotic/AI 'parents' for the subsequent mental and emotional development of the children.

    I don't think anyone should ever do that to any children. Bad enough to raise generation after generation of kids by adult choice - or indoctrination - aboard a "generation ship". Makes me wonder what they will be for if the mission is being undertaken by AI with robots? Pets? Leave aside how complex the technological capabilities would have to be and how difficult to sustain in the absolute physical isolation of a multi-generational voyage and distance from the economy that designed and made it, that this will be a much diminished branch of humanity for a lot of generations - narrowed options, not widened, and utterly dependent on tech they likely cannot understand, and only follow recipes to try and reproduce.

    I also don't think it will be possible to know beforehand if any target planet is suitable for being a target planet for occupation and conquest (any colonising being invasive) - or even if it is safe to breathe the air... for the humans or safe for that new world at large, exposed to the microbiome humans carry with them. Will it even be suitable for introducing potentially invasive terrestrial species, such as successful colonists might want for their gardens? The Trekkie vision seems to be of worlds with sentient occupants but would we even recognise them unless they use tech that is obvious? Any marine sentience with simple tech would probably not be visible at all.

  21. More than one wave of migration seems possible, even likely. That every wave was successful and thrived... maybe not. I recall reading about New Zealand, that the Polynesians that settled there, that modern Maori know as ancestors, found people already there, from prior visits. Hawaii likewise. Those people were not thriving and had lost their sea going capabilities. Possibly marooned? Certainly supplanted by later arrivals, possibly violently.

  22. The kids that didn't get rickets would do better and go on to have more and healthier kids as adults - bigger families - than those that did get rickets. That sounds like natural selection, not sexual selection yet mate selection would be part of it. I'm not sure how obvious any connection with skin colour would be; there will be different susceptibility to deficiency illness according to lifestyle and dietary differences as well.

    The more obvious mate selection criteria might be the unattractiveness of bow legged sick youths - choosing for health, not skin colour - but I suppose an enduring mate preference for lighter skins, as a sign of good luck re healthy children could emerge. But then again maybe we get coastal fisherfolk with dark skins and forest hunter gatherers with lighter skins.

  23. CO2 was drawn out of the atmosphere by plants, to become the food that human (and animal) metabolism turns back into CO2 - that part tends to balance, ie human respiration is returning CO2 to the atmosphere, not adding to it. However the energy used in farming, processing, transporting and packaging food is adding CO2 to the atmosphere to the extent that they rely on fossil fuels.

    Global average emissions are about 5 metric tons of CO2 per person per year - far more than respiration which is less than 0.4 metric tons per year. A more average Australian than me makes about 18 tons per year - it is humanity's biggest waste stream by a very large margin.

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