Ken Fabian

I find the visualizations of cells and biochemistry fascinating. Something like this gives a good overview -

All that nickel-iron (never pure iron going by meteorites) is material that was the core of planetoids that got smashed and reformed and smashed and scattered. I don't see how any superheavy elements could remain strongly differentiated (as specific asteroids) yet leave no traces anywhere else. Not if these asteroids (if they actually have such densities) were formed within the solar system. I am thinking it would have to have origins very different to what occurred in this solar system - supernova remnants or something exotic? - and somehow it never got smashed together with the rest. Yet if such elements were tossed out by supernova - and our solar system includes supernova produced elements - we should find traces everywhere.

I am very doubtful. It would be WOW if true but our solar system's Asteroid materials underwent a lot of violent mixing during their formation so traces of those superheavy elements should appear in at least some (maybe most?) of the 10's of thousands of meteorite specimens that exist on Earth. Or within Earth based rocks. Or are people suggesting these particular (poorly observed) asteroids are truly outsiders, that didn't originate within the solar system and have always remained separate? My money is on these results being wrong.

An alternate future for fossil gas drilling? The future demand for hydrogen is probably overestimated - the current biggest use is oil refining/desulphurisation and that ought to go down and some projections are for reduced overall demand, which may make fossil hydrogen look more reasonable. But I have serious reservations about Hydrogen outside some hard to decarbonise uses - fertiliser and other chemical feedstock. I would have expected iron and steel but there are other options that avoid the need. If it isn't produced, stored and used on-site the economics are poor and transporting it at large scales is not as easy or cost effective as it sounds . I'm inclined to agree with this -

Jonas - it is the relative scales that make water use a non-issue. The USA (as an example) uses about 100 billion litres of water a day just for household use. The scale of hydrogen production from electrolysis is still very small but even at large scale it will not be a large user of water compared to many other uses. And energy sources like coal use a lot of water too, to wash the coal as well as reduce fire risks at mines and transfer facilities. More water is used again for cooling at power plants. I expect overall use of water would go down with large scale use of hydrogen replacing fossil fuels.

Yes, I make a decision whether to attempt catching something I drop - and step back when I drop a sharp knife. On the other hand I use my feet, to break the fall of breakable objects; it doesn't always work but often enough it does.

Aircraft manufacturers haven't become the major airline operators; they sell/lease aircraft to other businesses, that operate airlines. lf a viable sub-orbital aircraft that can operate much like an aircraft (take off and land on runways and not require major refurbishing each flight) were developed by the major manufacturers I would expect airlines to be the ones to operate them. And use them on existing heavily trafficked routes, which can expect to make profits. Space? It needs destinations with sufficient traffic as well as the vehicles - or need the availability of vehicles to make the destinations. So far the companies making rockets aren't selling them to others to operate, but are operating them themselves, I expect because they are not yet reliable enough. They appear to require their own dedicated launch facilities and operators and such operations remain complex endeavors that are yet to achieve the stage of being frequent, regular and routine. Apart from space tourism with very high ticket prices the only available destination is the ISS - and but for rare, expensive exceptions, those trips and the destination are all paid for by taxpayers.

In keeping with my pessimism about grand space dreams... I think the only way humans could reach another star may be the slow way - migrating from deep space object to deep space object and building a new industrial base at each stop. 10,000 generations later, maybe... if they remember why or don't find their artificial habitats perfectly satisfactory. Or maybe if such a form of human civilisation can thrive it could become an expanding sphere that ultimately reaches other stars as an inevitability, without any set destination. Unfortunately I think establishing an industrial economy anywhere in space - let alone within a single ship - is extraordinarily difficult, next to impossible. We can have knowledge in a can - libraries, archives, training courses, AI virtual experts - but how big a population to support having living expertise capable of not just maintaining what already exists but expanding on it? Any specialty on Earth is going to have at least some extraordinarily capable individuals with living knowledge that goes deep enough for serious problem solving. I worked at a plastic factory for a time, that had problems with an extruder, that ultimately required an engineer from the manufacturer to fly to Australia to diagnose and plastic extruders aren't that complicated; I think having the designs and the availability of that kind of living knowledge underpins the viability of our industries. At least asteroid/comet/planetoid civilisations wouldn't have such extreme resource or population limitations and might achieve sufficient size to do more than struggle to maintain even a pared down, optimised technological minimum within a planned economy. Of course not all would go on the next migration.

I didn't think it was a question that hadn't already been answered. Doubtless I have missed something observed/published that suggested antimatter could be like flubber.

I think the advantage of tool making problem solving is that it overcomes physical limitations. Perhaps a mutant line of them needed head protection to overcome the vulnerabilities of an enlarged brain with thinned brain case to survive at all but the invention allowed them to survive where their hard headed cousins could not. A bit the way humans need clothing and shelter and fire to overcome lack of insulating fur and the products of invention allowed them to colonise environments even their furred relations could not tolerate.

Seems like we can use our senses indirectly, eg I can 'feel' the presence of an object using tongs, without actually touching it, just the tongs. I can be confident that it is a real object. Determining internal chemical structure by crystallography uses our senses very indirectly. Defining "real" as what we sense directly is way too narrow. Internal vs external doesn't look like such a clear distinction for human senses either. Some of our senses do work entirely within the body - even if much more internal "signalling" occurs without awareness than with it. Conscious awareness of an empty stomach or a full bladder is useful. Internal metabolic feedbacks aren't so useful to be aware of. Sure, the just five senses is wrong, even aside from things like counting skin detecting heat and feeling air movements from hairs disturbed by a breeze and being pinched all counting as a single sense (touch); equilibrioception (balance) for example isn't a sub-sense(?) of another sense, yet uses a variety of inputs that each might be viewed as a different sense, including skeleto-muscular positions and movements, visual cues as well as sensing movements of fluid within the inner ear's semi-circular canals. I don't know that there is an indisputable definition for "real".

@geordief I've never seen any animals eating fresh ash, but haven't been paying close attention either - I don't doubt the account that your donkeys do but I am surprised. I think some birds will dust bathe in ashes but I doubt they water bathe immediately after. Being wetted but the ash not washed away seems to be the point where it can be harmful.

I think fresh ash would be bad for frogs/toads, especially if subsequently exposed to moisture without enough water to wash it all off. Ash reacts with water and becomes strongly alkali. I also expect when animals eat ash it is ash that has been rain soaked and leached. Post bushfire rain runoff is notable for being very toxic to aquatic animals.

As noted the evaporative coolers work well where there is low humidity. What airconditioners can do is heating as well as cooling where Winters are not extreme - and the heat pump technology makes them exceptionally (above 100%) energy efficient for heating.

When people believe other people are bad then they can do horrible things to them without remorse - even feel a strong sense of satisfaction or enjoyment. What I find most disturbing about this - and it appears to be a near universal trait of humans - is that no proof they are bad is required for guilt and shame and remorse to be shortcircuited and for acts that can only be described as horrific to be acceptable. As long as we think they are guilty we can feel good about it, whether they are guilty or not and I think the worst atrocities happen like that.

High evaporation rates during hot and dry conditions is mostly potential for evaporation; as the moisture content diminishes from soil and (dead and dying) vegetation the actual evaporation rate does too. It doesn't make any difference to the flammability of the parts of the world experiencing hot, dry conditions at increased average temperatures; the evaporation during droughts doesn't deliver any extra rainfall where the droughts are occurring - warmer temperatures actually mean the air has to have a higher water vapor content to reach saturation (for precipitation to occur), ie it makes rain less likely. Having more rain in places that already have high rainfall - because warmer air in damp places takes up more water vapor and combines to increase rainfall - doesn't make damp places that have very low fire risks less flammable.

Sounds like we should expect Arctic sea ice loss to accelerate - due to Arctic Dipole moving from positive to negative - (Fluctuating Atlantic inflows modulate Arctic atlantification, Polyakov et el) - It isn't like it has stopped losing ice during the positive phase - arguably just lost less ice due to global warming than if it were not in a positive phase.

Boiling water also stirs and circulates the contents - you risk (a bit counter-intuitively) burning the bottom layer by reducing the heat.

Even dedicated fireproofed homes are at grave risk when the fires are fierce enough. Most of the homes lost in Australian bushfires had metal roofs. I recall an account of a house that appeared to have survived only to burn a few days later from a roof screw connected to a hidden timber that had started smouldering undetected - the heat on the roof and the screws were enough to have done that. Even where homes are built of non-flammable materials, they get filled with them. Rainwater gutters are a major fuel trap - we have mesh over our gutters but fine leaf matter does still accumulate; if it catches fire it can get under the roof. Recommended to plug the downpipes and fill the gutters with water ahead of a fire. Flywire mesh and draft proofing helps - fine mesh won't let flames pass through and drafts are another way extreme hot air and flames get into the structure. Water sprinklers are a big help but even that has limits, especially with limited water supply - town water supplies can struggle too, when whole districts have hoses and sprinklers running; I've chased ember spot fires with a hose that was down to a trickle whilst neighbors were all doing the same. Next step after all the fireproofing and preparation is having fire bunkers - often concrete water tanks remade for the purpose. That may be another step for us to take here.

There are a whole lot of factors. Here in Australia we are facing a potentially very dangerous fire season and the factors are feeling all too present to me. I've probably done equivalent to a day each week towards prevention and preparation over the past 6 months, removing undergrowth, piling and burning the cuttings, burning small areas of thick, dry grass, am partway through adding a sprinkler system, another water tank ordered. It is costing money and time in significant amounts. And if conditions turn bad enough we could still be forced to evacuate and no-one will be there to start the pump! So it will only help for less than worst case scenarios. We are not in serious drought yet but 3 wet la nina years saw exceptional regrowth that in large areas (including around our home) "ladders" to the forest canopy ie fires will readily reach forest canopies. There is "proximate cause" - what lights a fire - and there is the flammability - what makes it susceptible. Being hotter doesn't light fires but it makes it more flammable. I don't know if dry lightning storms are made more likely in places by global warming - it seems possible; our most recent very bad fire affecting this area started from lightning. When it is hot and dry and dead vegetation is approaching zero moisture content almost any spark will start a fire. Where there are people there won't be shortages of things that can start fires. I am actually astonished that we can get through any hot dry fire seasons without being burned out, yet very often we do. Beware the rhetoric of those who like to confuse and distract by conflating what makes it more susceptible and what actually starts a fire. I suggest waiting until post fire investigations are complete before assigning blame; we had a lot of fevered media excitement over alleged arson in 2019 but investigations showed very few cases of arson. Negligence, bad judgement and stupidity did rear their heads, yes, and "back burns" (attempts to contain a fire by burning back into it, ahead of the fire front) that didn't work as planned, with electrical faults and dry lightning storms major proximate causes. I recall a volunteer firefighter accused - even arrested - for a fire that saw multiple deaths; the fire was observe to start very near his home for no apparent reason. Proper investigation later showed he had been truthful all along and the fire started from a power line coming down further down the road; it landed on top of a wire fence strung on wooden posts. It shorted and sparked close to the poor man's house rather than where the line came down. A popular "blame the same activists who go on about warming" meme we saw was "environmental regulation prevents cool weather burning off". In my experience it hasn't been environmental concerns, it has been public safety ones that have been the primary reason for reluctance to do burning off. An influx of people onto smaller primarily residential rural holdings who lack the knowhow and equipment has seen (not surprising) a reluctance to burn off surrounding bush, especially larger areas. They are more likely to have environmentalist sympathies (and get labeled for it) but safety and potential liability for the fire that gets away seems a bigger impediment than ideology; I am not aware of environmentalist groups with policies of opposing the use of fire as a management tool, even if they want it done well. Also no surprise that fire authorities will call a stop to burning off when conditions get more dangerous, especially when so many fire permit holders are inexperienced and poorly equipped. But we are also seeing narrowing windows of opportunity to do so safely because of warmer conditions. Forest management for the very large areas tend to be inadequately funded as well; a lot more crews and equipment are needed to take full advantage of suitable weather conditions when we get them. We have had record warm Winter temperatures across much of Australia and that makes reduced opportunities; traditional practices quietly relied on cool overnight temperatures laying down natural fire retardant (dew) so fires lit the previous afternoon could be relied on to largely self-extinguish. With warmer winters and nights those conditions occur less frequently, across smaller areas. Increasingly we need more labour, equipment and effort to do the same things safely. Our lightning-started 2019 bushfire - started and out of control at the end of Winter - burned for more than 6 weeks in rough and inaccessible country before it came around us. The prospect of 3 C of warming - which will give above 4C around here - is a terrifying prospect, not only for hotter, more dangerous fires at the height of the fire season but shrinking opportunities to reduce fuel loads by burning off in the cool season.

Weather station data is used for most of the global temperature datasets and most of that is records of daily maximums and minimums. Looking at such records was one of the ways to determine whether we have been experiencing climate change and the reason most datasets start from the late 1800's. Ships also provide temperature data used for temperatures over oceans. Homogenization is done to make data in a variety of formats compatible with each other and to remove sources of bias such as different and changing weather station technology, shifting of sites and my understanding is some datatsets preference nearby rural stations over urban ones where urban heat island appear to make a bias. Comparing nearby stations that experience similar weather and temperatures is one way of identifying problem stations. Usually they divide the world up into smaller areas and average the stations within each before going on to make a global average from those - this is to compensate for some regions having a lot of weather stations and other having few; simply averaging all the weather stations together would distort the results by making it an average of the places with the most stations rather than truly global. The addition of satellite data provides consilience - ie shows much the same result by other means and affirms them, but it is even more reliant on processing the data, by means that are opaque to the non-expert.

What should we be doing that we are not already? I am all for education, healthcare and availability of contraception. And economic security and prosperity for all. All of which tend to lead, through providing enough freedom to do so, to choosing reduced family size. Population reduction other than by reduced birthrate and attrition over multiple generations across multiple nations seems especially problematic. Regulating which people can and can't have children and under what circumstances - rather than who lives and who gets murdered - has serious ethical as well as practical issues too. Education and encouragement is fine - let's do more where we can - but I am not convinced we should be trying regulation and enforcement. I think some of our more serious population related problems won't give the time for population reduction to help even if we could force it and I feel a sense of foreboding about that. An aside is I don't think global warming is primarily a population problem - I think it is a dirty energy problem and per capita emissions problem. Good governance is essential, yet the worse the external conditions the more likely it seems that we will get all that bad governance can give - blameshifting and divisiveness and conflict. Things going badly seems to enable and encourage exploitation and corruption; desperation leads to looking out for no.1 and life becoming a zero sum game and that is not conducive to good governance.

Surely storing DNA is the easy part; it is the rest of using that DNA as backup of Earth life that we are not capable of. ie turning frozen samples into live, independently capable organisms. I suppose it would have to be many species, sufficient for working ecosystems. Capable because some animals will fail to learn necessary survival skills without parental care within a working ecosystem. Or is it just homo sapiens and species we know we depend on that we would be seeking to preserve? I expect it to be a lot more complicated than just having the dna of humans and food species; the interdependencies get complex. I keep coming back to the requirement for a comprehensively capable advanced economy independent of Earth for surviving beyond Earth; being able to support advanced biotechnology beyond what the most advanced nations are currently capable of is no small thing, on top of supplying more immediate needs. I think just immediate needs will be so extremely challenging as to be prohibitive.

No, my assumption is it isn't feasible. If it were close to feasible -and I do think the economics of it is indicative - maybe but it isn't anything like close. That thousand fold lowering of costs - more like 10,000 fold to get near across the planet ocean shipping costs underpinning global trade - makes a barrier that wishful thinking cannot overcome. That there are real extinction risks is why I support meteor defense as an enduring space program objective. If drastic cost reductions emerge then we can reassess where that line for feasible is. Space is not the place for depending on improvising or any go there then figure it out "bootstrapping" - everything needs foresight, planning and preparation. I don't think that is true, even leaving aside just how out of reach "once you conquer colonising space" is. Sure, you can throw a stone in space and it will keep going but getting it to reach a specific destination is a whole lot harder; getting to and from actual destination in space is still hugely energy expensive and technically challenging. Just going from low Earth orbit to Geostationary costs about 1/3 of the delta-v ie fuel requirements and wear and tear of what it took from ground to low orbit - that is still a LOT - and requires a lot of reaction mass as well as energy to do it. From low orbit to moon takes 2/3rd of what reaching orbit did. To Mars from Earth orbit it takes about as much as reaching Earth orbit, but without atmospheric braking to save fuel. Solar power does seem to offer some potential where low accelerations suffice - I'd suggest very high temperature vaporisation, maybe to plasma, of (probably) water rather than attempting to turn it into chemical fuel, but the reaction mass to payload ratio is still going to be very high. There are some useful resources in great abundance out there, with nickel-iron the pick of them, with 10's of ppm of platinum group metals included, if you can refine them, but not every resource is abundant. For example I struggle to see how fission rockets can be fueled in space without accessing fissionable materials from Earth - which may be in high demand. Fusion is still a work in progress. But even with such energy sources there is a lot of reaction mass needed. I'm not opposed per se - just think it is a lot harder than the optimists like to think.

On the other hand I remain unconvinced and very pessimistic about space colonisation - that without commercial profitability to enable a colony (which I think has to be at least equivalent to an advanced industrial economy to have a chance) to pay it's way and be self supporting human habitation of space won't happen and without extraordinary transport cost reductions - far beyond anything in progress, at least 1/1000th current best or better - commercial profitability that can make it an opportunity will remain out of reach. I also have the unpopular view that uncrewed exploration delivers more with much better value for money than crewed and the greater scientific/exploration achievements will continue to come from that. But, being Australian my influence - posting opinions on science forums - is minimal, even less than the vote an America gets.