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Ken Fabian

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Posts posted by Ken Fabian

  1. I once tried building a "perpetual motion" machine not too dissimilar - not because I thought it would work but to work out what I was missing, to understand why it wouldn't. Needless to say it didn't work and I saw the push of magnets equaled the pull, with friction as well.

  2. Seems like a tipping point on relative costs has been crossed. The economics of renewables has never been better and that has to be the case for massive growth of it to be possible as a policy. Not so much deep, long planning as taking advantage of the extraordinary cost reductions for RE; even one decade earlier and the IRA would not have been possible.

    I think carbon pricing can only work if there are available alternatives for energy companies to invest in that are approaching cost parity - which is only recently the case for RE for much of the world and is more difficult for a nation with extreme winters like Canada to take advantage of. More long connectors to the USA to take advantage of cheap solar out of season? More wind and hydro? More nuclear? But sticking with fossil fuels is not a good option.

  3. I'll wait until one happens where I am - 2030 looks good for here. The last time I was where a full eclipse happened (suburban Sydney) the hush that descended was a surprise - most people headed inside (to watch on TV?) and the traffic mostly stopped. It seemed like some people were spooked (and fearful for children) as much as they were interested and the park we headed to was nearly empty, only one person with a telescope. Didn't have the gear ourselves to view directly - but did the pinhole thing and saw the impression. Mostly we observed the effects, like the sharpening shadows as it became a crescent, saw stars and watching/listening to birds, some doing their morning calls as the light came back.

  4. I think the vulnerability of airships to bad weather is their greatest weakness and that isn't different by using hydrogen  - there are uses for them but they are limited.

    I am still a bit surprised there haven't been serious efforts to use hydrogen by improving ways to do so safely; I am sure it could be done a lot safer than a century ago. And most zeppelins back then never caught fire. Dramatic examples of things going wrong don't necessarily mean they are very likely or cannot be avoided


  5. @CharonY That is interesting and shows I don't know as much as I would like to. Thanks.

    Some green light gets used by photosynthesis yet a whole lot of green light goes unused by Earth's dominant plants or it would be absorbed, not reflected nor pass through leaves so much; I am still inclined to think the biochemistries that can do photosynthesis well could be limited and stronger green light won't necessarily lead to plants that use more green light more effectively.

  6. A different opinion here. I expect that the light from other stars will still have a lot of energy across the whole visible spectrum, that eg Blue stars don't make only blue nor have a pronounced lack of red light in the spectrum and Chlorophyll a and b would work just fine.

    Despite the amount of energy available to Earth plants between Red and Blue they have not evolved photosynthesis that utilises Green effectively, despite the great abundance of green light - the limitations may be in the kinds of photosynthesis chemistry that work and the other, non chlorophyll sorts of photosynthesis (some not doing CO2 to O2) are less effective. Maybe plants elsewhere will manage with Red and Blue photosynthesis (and look green like here)  because those kinds of photosynthesis are easier for biochemistry to achieve.

  7. @Carrock

    Seems to me we would try for Near Earth Objects (NEO's) by preference. Atiras asteroids are inside Earth's orbit around the sun without crossing it, Atens are inside but do cross it, Apollos are outside and cross it and Amors are outside and don't. They seem likely to have recurring "windows" where lowest delta-v will be possible. I wouldn't start with the Asteroid Belt.

    I've suggested C-type (carbonaceous) asteroids by choice, for the water content (for reaction mass) however in general those are more likely to be found further out in the solar system and the Near Earth ones more likely to be S-type (stony). All probably contain nickel-iron but whether they contain carbonaceous or others suitable for extracting fuel/reaction mass is not clear. But the fact that carbonaceous meteorites are common suggest that carbonaceous asteroids could amongst those NEO"s. And if going further afield then there are Mars' moons, which appear to be carbonaceous. Any potential target would deserve some survey sampling.

  8. @Phi for All

    There may be imaginary "better" uses in space - never any shortage of those - but the only advanced industrialized economy that actually has high demand and high value uses for PGM's and can pay for them, the only one at all - is Earth's. The 'but we can use in space' is sort of right; most of what any proposed asteroid mining operation produces will be for use in space, as essential to being able to deliver resources of high value to Earth - like fuel for the rockets. There is no independent space economy only outposts of Earth's economy.

    Sure, if my proposed test case worked it could deliver small amounts of usable asteroid materials eg water, raw nickel-iron, carbonaceous material to NEO there could be demand for them from whatever space stations there are. But what are those space stations doing that makes a profit? I've asked this before but no-one can answer without getting all imaginary. Taxpayer funded space stations that make no profits using such materials may reduce their costs doing that, but the overall totality still relies on Earth subsidy, just a bit less direct.

    I don't think any projects in space can achieve self perpetuating growth unless the economics work. What are those activities in orbit that pay their own way with enough left over to support future growth? Subsidy until it works isn't good enough; we need a lot better than that to commit the levels of investment needed.

    Without a way to deliver tangible returns to Earth investors it is just dreaming.

  9. @GeeKay the alleged values don't mean much and any mining attempts, if ever, are likely to start small and probably continue to have a lot of very high costs to recover before achieving profitability - and not much affect the market price.

    I am amongst the more pessimistic commenters when it comes to space but the resources in asteroids are real - notably Platinum Group Metals mixed in nickel-iron at 10's of parts per million (going by meteorite samples). Even the nickel-iron, raw and unrefined would be considered valuable here on Earth, just for the nickel content. Most things in space have no potential to make money but asteroid minerals are a real "prize" of enormous potential monetary value, so I think the interest will always be there.


    3 hours ago, exchemist said:

    My understanding of this subject is that the killer, economically, is the huge cost of the change of momentum required to bring extracted minerals back to Earth. These asteroids are on a very different orbit from that of the Earth and momentum change (rocket power) is very expensive, per kilo of payload.


    Yes, the differences in velocities are huge; most of any asteroid mining/refining operation would be making enough fuel/reaction mass for the rockets, which must have exceptional durability and long working life. That is probably the first test that needs to be passed - a rocket that can do a round trip between asteroid and LEO exclusively with "fuel" (and other consumables) produced out of asteroid resources. And do it over and over reliably with absolute minimum of ongoing supply from Earth.

    Probably not an M-type. We need to know what those rockets will run on and know if a target asteroid has it. Off the top of my head I would target C-type; going by carbonaceous meteorites they contain the target mineral - nickel-iron with PGM's mixed in - as nodules and grains within a softer carbonaceous material that also contains significant amounts of water.

    Can solar electric arc-jets use simple water for reaction mass? H2 + O2 chemical rockets present serious problems, including very large tanks as well as, ultimately, inadequate performance. I think things get harder if any rocket uses requires more exotic fuels, eg the Keck Institute of Space Studies proposal to capture a small asteroid and return in to near Earth space with a solar electric rocket using (if I recall) xenon for reaction mass. Seems very unlikely to find a source of xenon in an asteroid. Hydrazine is used with arc-jets and it seems possible (with water and a source of Nitrogen and equipment) to manufacture it, but water, even if less ideal, presents a simpler challenge to produce and store and use.

  10. Close planting - more like 1 per m2 rather than 5 - is common practice for forest regen projects here in Australia, and I expect worldwide. It mimics the mass germination and growth from broken canopy in natural forests. Attrition is of course part of that; you end up with a very few mature trees. The pre-colonization mature forest where I am (if I am recalling correctly) was around 6 to 12 trees per hectare. Big trees. The regrowth forest present now is in between - maybe near a hundred trees per hectare after much higher numbers of (naturally germinated) seedlings and saplings.

    Had the original land clearing intention been followed through the regrowth would have been prevented as far as possible and over time the soil seed bank would deplete - and planting becomes the only way. But natural regrowth favours some species over others; there is no expectation that what will regrow will have all the same species in similar proportions. And some species never really recover, including some of the most prized timber species, that were mostly gone before the land clearing and haven't and won't ever recover. The glib cutting trees down promotes new trees, more than before defense of widespread exploitation of old growth forests was and is a half truth; we get lots of smaller trees dominated by a few species and the ecosystem is different to the original.

  11. 7 hours ago, geordief said:



    "The Tiny Forest concept was pioneered by a Japanese botanist, Akira Miyawaki. He pioneered a special method of planting and ground preparation that can be used to grow forests ten times faster than a typical forest (which usually takes 200 to 300 years"


    "Usually up to five saplings are planted for every square metre and as a result, the trees are forced to grow upwards for sunlight instead of spreading outwards"

    I'm not sure we know how any typical forest planted now will be faring in 200 to 300 years; do we choose which species to grow based on what the climate is now or what we expect it to be? Sounds like a concept with benefits to farmed and gardened forests but not necessarily useful at very large scale.

    There are good reasons to have forests and natural ecosystems but emissions mitigation isn't one of them. I think it is more appropriate to think of the CO2 reforestation sequesters as counting towards reductions in land use emissions rather than to justify ongoing fossil fuel burning.

    The impacts on emissions of mass forest plantings are going to be complex but ultimately they'll be finite and won't exceed what was emitted from prior deforestation; this kind of forest cultivation might take down the Carbon faster but it will reach peak biomass faster and stop being a carbon sink sooner.

    I don't think we can depend on sustained, non-reversible increases in global biomass to make a significant difference to the climate problem. If it doesn't reduce fossil fuel burning it isn't fixing the climate problem. And in my view it is a travesty to plant forests in order to protect fossil fuels from global warming.


  12. To be serious about zero emissions we need these kinds of mechanisms in place in the world's major trading economies. Preferably pricing at rates like we really mean it, that ramp up predictably over time, like we mean it and without rafts of exemptions and exceptions, like we really mean it.

    But anything tariff related gets bent by geo-political concerns and I fear that anti-China sentiment will be used expressly to impede global growth of RE and EV's, in ongoing efforts to save fossil fuels from global warming.

  13. On 2/14/2024 at 9:38 AM, Zenith29 said:

    Though there is a lot of importance given to renewable energy but is it really not the solution to energy problem because 

    nich market and a tough competition with existing fossil fuel industry 

    it is still expensive 

    Is not 100% reliable 



    If you want to make arguments to support these assertions you are welcome, but stating them doesn't make them true. In my experience pretty much only staunch doubt, deny, delay opponents of addressing global warming seem chronically unable to update what they are sure they know about climate science or climate policy or options for doing something, like renewable energy.

    Around 3/4 of all new electricity generation being added around the world is now solar and wind, on their merits, as commercial decisions - not out of deep commitment to zero emissions (although the possibility of emissions accountability emerging in the future does figure into investment decisions) but because of this -




  14. 1 hour ago, TheVat said:

    Agree if the projections are with chemical propellants supplying the delta vee.  Which is why I respect sci-fi writers and futurists who take some trouble to posit different propulsion systems, carbon nanotube elevators, etc for their robust off-planet futures.  But for sure, chemical rockets are cranky and expensive AF.  And likely to remain so.

    Sure, with fictional propulsion systems the impediments don't look so overwhelming. Reality is not so easy.

    Not that I would expect chemical propellants to be the favored choice apart from the initial launch - I would be looking at solar electric/arc-jets using asteroid water for reaction mass (or something like), ie something with barest minimum of consumables sourced from Earth. Whilst examples of electric arc-jets do exist that is not the same as large scale, long lasting versions with proven extreme reliability suitable for such a job; every part of such a mining project would be bespoke.


  15. I have no fear of corporate tyranny in space because space lacks opportunities for profitable enterprise. It is only in fiction that there are opportunities that are worth the effort. Space companies milking the taxpayer funded agencies is a depressingly ordinary kind of bad behavior.

    Unless there is something I am missing, something big, it looks like if we take away the taxpayer funding there is no self funding commercial opportunity in space exploration or any space activities that don't directly service Earth customers. I don't count transporting astronauts to and from the ISS - or the ISS itself - as self funding.  No space tourism venture comes close to recovering costs, let alone makes a profit. If anyone can point to anything we do in space apart from ground sensing and communications satellite services that earns income from Earth customers and can be self funding I'd be interested.

    Asteroid mining, in potential, is the best I can see and even that appears to be far short of viable.

    For unashamedly taxpayer funded ambitions in space I think meteor defense is as good as it gets - far reaching enough to support ongoing space R&D with big ambitions, with multi-nation participation, that might end up opening up and spinning off something commercially self funding, but will be worthwhile even if doesn't.

  16. 3 hours ago, iNow said:

    Approximately 70% of those considered wealthy are self-made according to multiple analyses, but they tend not to give credit to market returns (aka: luck) where that’s clearly a relevant factor. 

    I expect the rate of success for self made wealth from initial poverty is very low compared to those starting from even modest (well short of "wealthy") inheritances - or just with families that can afford to be loan guarantors. "Just try hard and you will succeed" works much better for those with existing resources to draw upon - including being able to try again if not succeeding first time around more readily too.


  17. I prefer to have the video contents summarised for discussion - if I watch every one that gets suggested to me there would not be enough hours.

    I don't doubt that, given enough funding, aerospace companies will attempt Mars sample return missions, with reasonable expectations (but no guarantee) of success. But I expect it to continue to be easier and more cost effective to send remote operated robotic equipment to Mars to analyze mineral samples than bring samples back. If something of exceptional interest worthy of the kinds of study that can only be done on Earth gets found then the case could be made for a sample return mission. The knowledge is what is valuable although no doubt the samples would have collector value.

    Not sure the extent to which Mars colony hype influences exploration priorities but it seems to be explicit in objectives for many Mars missions.

  18. I think it is an oversimplification - or at least the quoted bit without the context and explanation of what that means could be misconstrued.

    Yes, some individual critter was a common ancestor of both baboons and humans, but it was not their only ancestor (or even only pair of ancestors). Their progeny would be a lot more like the parents and parent population than like baboons or humans and I would expect generations of "common ancestors" for each to coexist and for some of (and possibly all of) their progeny to also be common ancestors of both later lines. A whole lot of evolution would be still to come, including some cause for divergence into separate populations.

  19. As for restricting home computers (the OP) - the deaths of innocent victims from AI are hypothetical, and even more hypothetical from home computers. Deaths of innocent victims from misuse of assault rifles are not hypothetical.

    Not sure many home computers can even support the kinds of AI that can (hypothetically) be dangerous; AI as a tool used nefariously by military and intelligence services (including by despotic regimes) seems more likely to me than rogue AI. But assault rifles are designed for one purpose - injuring, maiming and killing people. I'd prefer that power to use such force be in the hands of trained people who understand proportional and appropriate responses as well as operate within the rule of law. (Which I would want to be the case for government agencies using AI as well).

    In functioning democracies with rule of law armed citizens rising up to support and protect their government and institutions when attacked by enemies, including insurrectionists makes more sense than as a standing tool, just in case, FOR insurrectionists. Without an existing, credible threat and absence of military capability to face it there seems no good cause for a standing armed populace.

    No government as better - Libertarianism - is delusional; the solution to bad governance is better governance, not absence of governance - and a lot of nations with high levels of personal freedom have made their institutions, like independent courts, their bulwarks against tyranny.

    From outside the USA it looks like the day the armed populace there rises up will be the nation's ruination - those weapons are for use against other Americans and the designation of "enemy of America" for those with different politics, religion, ideals as promoted through free speech and voting will be self serving justification at best. The historic Revolution may be the aberration, where the winners did not put themselves above the rule of law - eventually - once those who supported the King were ousted, or summarily executed, or had their property taken or were forced to flee (to Canada).

    The kinds of insurrection the US faces now doesn't look legitimate in any sense, and unlikely to result in greater freedom or prosperity even if it succeeds.



  20. 1 hour ago, Photon Guy said:
    On 1/24/2024 at 5:43 AM, swansont said:

     Or just use an electric vehicle.

    You could, but that wouldn't have the horsepower of a gasoline vehicle. 

     Not correct; a gasoline vehicle might have greater range than an EV but weight for weight the power of electric motors beat ICE easily by a huge margin. If the vehicle has to carry oxygen as well as fuel an ICE won't have much range either. And if you have to bring the fuel AND the oxygen (or oxidant) from Earth then EV's running off solar power looks like the better choice every time.

    Somewhere like the moon might manage with direct solar power for 2 weeks out of 4; large lightweight solar wings in vacuum would not even present serious stability problems without wind - but may need shock absorbing stabilisers for rough ground. Or unfold and unfurl them when stopped to charge batteries. Traveling by lunar night would probably present other problems besides energy storage - scheduling to avoid it may be more practical.

  21. All interesting, if disappointing. Does it mean this - "Demonstration of resonant tunneling effects in metal-double-insulator-metal (MI2M) diodes" (a demonstration of an optical rectenna in IR) only works because the source is in phase? Would not work otherwise?


    The rectenna was illuminated with 10.6 μm linearly polarized radiation from a pulsed Synrad 48-1SWJ CO2 laser. The laser source was pulse width modulated by Agilent 3220A function generator at 20 kHz. The noise level under dark conditions was determined by having the laser beam pass through a ThorLabs SH05 shutter. A half-wave plate (ThorLabs PRM1Z8) was used in the optical path to rotate the laser polarization with respect to the antenna axis. Rectified voltage and/or current responses were measured by a lock-in amplifier (SRS830) and the reference signal for the lock-in amplifier was generated by a mechanical chopper at 1.8 kHz.

    I suppose that means it was in phase but I don't know. "Linearly polarized" ? "Modulated by a 3320A function generator"? Polarized to a specific axis?

    It is all beyond my paygrade - but my surmise that it had to do with the heat emissions of the receiver overlapping with it's tuning seems wrong as well.

  22. On 1/17/2024 at 3:01 PM, sethoflagos said:

    You're effectively claiming the ability to extract useful work from a system at thermal equilibrium.

    Not sure there's anywhere to go from here.

    I don't know why Dr Novack thinks it but I think it because I think the photons interacting with an antenna don't add (all of) their energy as heat to the antenna, some energy making electrical potential. Some gets converted to electrical energy and carried away. It may initially be at thermal equilibrium but it isn't a closed system. Note, I don't think this as a certainty - I don't know enough.

    But if the antenna can't absorb IR because the temperature of the antenna makes it radiate IR - not the antenna transmitting IR because that takes electricity from somewhere else, but the materials radiating it in the normal way things that are warm radiate - then, yes, it is at thermal equilibrium and an IR rectenna cannot work.

    I had thought that interaction between EMR and an antenna was independent of antenna temperature but that was most likely ignorance - most working antenna aren't tuned to the band the antenna normally radiates in.

  23. @sethoflagos

    I understand that antennae work as transmitters and receivers (but little real understanding of how they work). I am simply looking at energy flows. Antennae do turn EMR - if only narrow bands of it - into electricity and that energy is not being absorbed into the substance of the receiver. Simply, the energy that is diverted away isn't turned into heat in the receiver. In an otherwise closed system it has a leak; there will be loss of energy, ie cooling.

    Are you (or Kirchoff) saying an antenna won't work if the substance of an antenna radiates within the band it is tuned to - that IR emissions (specifically) are too close in wavelength to the receiver and prevent it working?

    This may indeed be the case - ie there isn't any flow of energy away as electricity in a rectenna tuned to the bands that materials radiate heat because it doesn't work. But at shorter or longer wavelengths - outside the IR - they will? Yet my understanding is optical rectennae have been shown to work - albeit at very low conversion efficiencies; at just what wavelengths, at what temperatures and under what conditions I don't know.

  24. Thanks Sethoflagos. I admit I still can't say I understand.

    14 hours ago, sethoflagos said:

    Okay so far. But note that emission by the antennae is NOT independent of the temperature of the antennae,

    Seems to me the materials of an antennae will get warmed by what the antenna doesn't turn into electricity - but a warmer antenna should work at similar efficiency as a cold one, it not being a thermal phenomena; unlike an ordinary material less energy/heat is added to the material of an IR antenna than the total energy received and absorbed by it. I still think diverting it away as electricity diverts energy away from the combined emitter + receiver and should result in loss of energy within them, ie cooling.

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