Ken Fabian

I suspect that as long as some nations feel entitled and even obliged to keep them as their weapon of last resort they will be sought by others to be theirs. They do seem to be highly prized status objects for a lot of nations, even ones with well equipped "conventional" militaries. Given the prevalence of "maximum force" style of military logic - more prevalent I suspect than Sun Tzu inspired "winning without engaging the enemy in battle" style - it's difficult to believe someone won't use them. Perhaps when faced with losing a war by other means. It chills me to know that Kennedy was being advised to use them - by people who really should have known better - during the Cuban crisis; I'm not convinced some other US Presidents and Presidential hopefuls would have been able to say no. I do think it's hubris to think these things can't be developed independently, using novel pathways, by nations with a solid foundation of civilian nuclear technologies.

HB of CJ certainly ticks many of the standard boxes when it comes to rejecting what science tells us about messing with the concentrations of greenhouse gases of our atmosphere. Follow the money? I think the bedrock foundation of high level mainstream political support for climate science denial and obstruction is about avoiding the perceived economic costs that flow from acceptance of climate responsibility. To what extent politics leads or follows is probably irrelevant but I think the most politically influential sector of modern nations is commerce and industry and the larger parts of those have decided where they stand based on how it affects their bottom lines in the near term; that desire to avoid the burden of costs by rejecting responsibility flows upwards from affected businesses as political lobbying, downward to their workforce as fears about job security and further downward into the gutters of PR, advertising, tankthink and other forms of ethics deficient opinion for hire. Economic Alarmism tends to trump Environmental concerns - except that climate change is definitely a serious economic issue that will affect prosperity and international security on unprecedented scales. But the latter concerns are about timescales of multi-decades, centuries and millennia whereas the former impacts people and their choices much more immediately. It doesn't appear to much matter that solutions are within our reach and are unlikely to result in widespread economic disaster - for those sectors that are most directly affected, the burden of climate responsibility is indeed a financial disaster. Yet, unlike the more usual case for an activity that is shown to have serious harmful consequences, the opportunities for (unofficial) amnesty for past actions and an orderly transition that allows major investors to avoid major losses and liabilities are intrinsic to the policy responses proposed. Science is conducted within institutions, conventions and practices that are bound by professional ethical standards - practices that are reinforced by accurate and open record keeping that allows and encourages independent expert review and critique. And then there are institutions like the National Academy of Sciences and Royal Society that call on the very best of scientific expertise to provide independent advice to policy makers.

I suppose we should add safe deconstruction and disposal to the essential project specifications.

I think this kind of engineering needs to have large safety margins built into it - so if the currently available materials are only just sufficient for the structure to support itself that won't be nearly good enough. I doubt static charge or heat conduction are likely to be real problems. I don't know if carbon nano-tubes are tolerant of heat and cold - certainly they are good heat conductors - but whatever is proposed needs to consider the heat differences between full sun and Earth shadow which are, by ordinary standards, extreme. Exceptional heat conductivity may be an asset. Vacuum diffusion and erosion from charged particles may be issues. Weather will affect the parts in the lower atmosphere and add sideways stresses that may be severe during extreme weather events. It may be that there won't be any solid materials good enough, but perhaps some kind of chained electromagnets that achieve greater tension than a physical material? (I don't even know if that is even theoretically possible - probably not, if the electromagnets themselves get torn apart by the tension!) That then introduces a whole new set of problems, including power supply that absolutely cannot ever fail. Then there is the actual construction and installation - during which there may be additional stresses, such as if the bottom end were dropped down (flown?) from orbit and anchored. As a thought experiment it's interesting. As an engineering project it's not feasible and it may well prove to be forever unachievable - unless we see some extraordinary technological advances of course. And I suspect that technological advancement, despite the achievements I've seen in my nearing 60 years, ultimately will approach physical limits that aren't going to be amenable to techological workarounds or allow exceptions.

my thoughts? These 'free' energy devices sound like a version of a perpetual motion machine, but there are good reasons why they don't ever run continously or produce more energy than was initially put into them. The output of an alternator or generator will be equal to the energy the motor driving it uses minus the waste heat from friction and other inefficiencies. The output of the generator will not be enough to power the motor under load and the combination will run down and stop. I suggest looking up the law of Conservation of Energy or First Law of Thermodynamics. The best "free" energy devices are things like photovoltaics that turn an existing abundant energy source that we don't use into a form of energy we can - and even those will never be entirely free and don't ever make more energy than was there in the first place.

I saw that - perhaps one of the best graphic representations of historic global temperature so far. Maybe the IPCC could learn a thing or two.

EdEarl; actually I've been impressed by how many new battery options are becoming available, the rate of improvements and price improvements. Still a long way to go but compare to even a decade ago, when a home PV solar installation had the option of Lead-Acid or none - and those were almost exclusively for remote area off-grid applications. Hybrid grid connected systems that included storage were not even on offer, whilst now almost every installer offers it - I think we have come a long way quite quickly.

Motorcycles are more dangerous. Yet every situation can be different. Recalling a terrifying close call whilst riding - I spotted a job vacancy sign on a factory front and was looking at it as I approached the top of a rise and returned my attention too late; traffic was backed up and I was going way too fast to stop behind it. Only hard braking and swerving just in time - still travelling quite fast - to pass just on the verge side saved me from serious injury and possibly death. But had that happened driving a car I could not have swerved around like that. The consequences might not have been so deadly in a car but it would have almost certainly been a serious collision.

I suppose that is true - and the willingness of commercial enterprises to invest in battery development suggests results are seen as achievable. Interestingly most of Tesla's batteries appear to be based on a type of Li-Ion that isn't cutting edge; it sounds like economies of scale and optimising the production of them has been how they've reduced costs. Still, I think the fundamental research that tends to be more reliant upon taxpayer funds is probably still crucial to making the big leaps possible and I'm not convinced energy storage has been strongly supported - not relative to the scale and importance of the climate/emissions/energy problem.

The combined resources of the most technologically advanced nations hasn't built a single working fusion power plant. Being optimistic is okay with me but improving energy storage looks far more likely to have significant and tangible impacts on our energy systems. Whilst I would not like to see such efforts to develop working fusion cease I would like to see advanced energy storage research - which looks to have enormous potential for viable results on shorter time scales - get more support.

I think we are better positioned to invent, improve and produce better batteries than ever and the motivation to do so has never been stronger. Stationary storage and transport suitable storage are different enough that they may be done by very different means, however any EV suitable battery that is low cost enough will - as Lithium in several forms is already doing - be potentially able to compete as stationary storage. I think flow batteries - still have a lot of potential in stationary applications, with it's expandability of storage capacity independent from charge and discharge capacities. Vanadium redox, for example, can offer endless re-use of it's electrolytes. True recycling at as good a quality as the first time use, rather than the 'down-cycling' that we are more familiar with - that puts a few steps at best between first use and becoming waste that is degraded beyond all re-use - is an important consideration. I think the capability for true recycling is important for everything we produce and use - but that kind of technological optimisation may take far greater community awareness and concern as well as far more political maturity than we currently have and perhaps only after squandering what appears plentiful and facing the costs of scarcity will that become a routine design consideration. Demand for Lithium may well prove a significant barrier but it is not the only chemistry that will be used and I think there is still room for some big surprises. Certainly if there isn't enough of it - sending lithium prices soaring - that may drive the market towards alternatives. I don't expect transmutation of elements to ever become a source for battery materials.

EE - it's not clear from the map Sensei included what sort of geothermal it shows. I suspect it may be or include hot rock geothermal, which is not hot because of heat from magma, but from long term internal low level radioactivity.

Maybe they have greater choice, but perhaps they suffer more harassment, greater likelihood of rape or be more at the mercy of macho competitiveness, where the alpha male gets - by intimidation of other men, the women and their family - the girl he wants.

Agree there is a strong correlation with education. Availability of affordable contraception, especially to women independent of husbandly permission would be a big factor. Dramatic change to birthrate can have awkward consequences down the line though. re China, the skewing towards boys over girls seems likely to create an enduring influence towards lower birth rates, even though the one child rule looks like it's being relaxed. Has that imbalance been advantageous to the girls or made them more vulnerable? How high populations, raised on unsustainable foundations, interacts with the upcoming impacts of global climate change, with it's high potential for exacerbating droughts, floods, coastal inundation looks very worrisome. I suspect refugee issues will only grow - and they won't only be about crossing international borders; movements within nations will raise tensions.

EE - there are different types but the most readily usable is in volcanically active areas. It can range from using the hot water that wells up for heating, to drilling down to where the water is at higher than surface boiling point - kept liquid by being under pressure. It boils from it's own heat once the pressure is removed, ie raised to the surface. Usually doesn't require pumping. More geographically available is what we would call Hot Rock Geothermal - or Enhanced Geothermal. It makes use of geological hot zones, often deep granites that are heated over eons by their own natural low level radioactivity; fracking allows water to be pumped down and through shattered hot rock, to return from a nearby second well heated at above surface boiling point, like the tapping of natural deep hot water mentioned above. Ultimately the heat is used up. Another kind of geothermal is heat pumps, that are used for small scale heating, using a variant of Refrigeration or Air Conditioner type technology, that absorbs heat from buried pipes at relatively low temperatures - by cooling the fluid first, pumping it down where it's cooler than the ground, where it absorbs heat - then allowing it to be released at higher temperatures. Usually the piping is buried at a depth that allows seasonal reheating, ie over summer, and deep enough that it remains available through winter. It works the same way a fridge pulls heat from food and the heat is released at above room temperature in a radiator at the back. It's advantage is that the process doesn't use as much energy as it picks up from the ground and releases where needed, making it an attactive home heating method.

Interesting idea to have each mirror independent and mobile. It would get down to relative costs and on the face of it they would be more complex and likely to be less reliable which may eat away at any advantage in site preparation and maintenance. Autonomous robotics may be put to better use ... in site preparation and the manufacture and maintenance of permanently placed mirror assemblies.

From afar it does look like religion has a powerful influence within US politics and also like those religious views that tend towards climate science denial lending weight to denial by many politicians. This may not be an accurate reflection, despite some of the Presidential candidates making utterances I took that way. Australian politicians are less likely to express their religious views so openly but they are certainly there. And I suspect for some it verges on being a crusade kind of war, where being misleading and deceptive and even outright lying about their true views and intentions is viewed as something forced upon them by a creeping evil of Political Correctness. The Archbishop Pell example I used looked to me like a mixture of seeing human progress built on fossil fuel use as reducing human suffering and therefore unquestionably good - thus those calling them bad and demanding their use be restricted and replaced must be dangerously misguided. That, combined with aversion to 'alternative', hippy style embrace of non christian, paganistic beliefs, widened to include anti industrialisation style environmentalism such people often espouse. To me it looks like he took the willingness of those demographics to loudly promote the climate issue as evidence of them being it's source - which in turn looks like accepting the framing by early opponents of climate action of climate change being an issue driven and led by a ratbag, irrational fringe. They may have been some of the loudest voices but only because the mainstream was keeping heads down and mouths closed. That framing was, I think, largely political expediency, aided by the failure of mainstream politics - their silence or criticism of the science - to take the scientific advice seriously, cementing the view that such people and their unwelcome solutions were at the issue's foundations. Wjhilst Pell himself felt quite entitled to pronounce on the falseness of climate science, his main criticism of The Pope's position was that The Church shouldn't be doing science or pronouncing on the truth of climate science. I don't know how theology sees human prosperity and suffering - whether God sees it in relative terms or absolute? Because there are more people today living malnourished and in poverty than the entire global population back when The Industrial Revolution was gaining momentum, even if more are prosperous and relieved of sufferring in proportion to total population.

Yes, and, as I understand it, there was an actual effort that including inviting leading scientist to The Vatican, to better understand the science prior to The Pope's pronouncements. I would note that Australia's Archbishop Pell has a history of strident objection to climate science, including likening it to a new green paganist religion to be rejected by good Catholics. He also promoted such views via handouts to every child at catholic schools in the lead up to a previous election in Australia as well as addressing the Global Warming Policy Foundation - with a thorough reiteration of most of the main climate science deniers' arguments. He may be keeping his views more to himself because of the current Pope but not without some criticism.

Religious people, by virtue of their numbers and influence, are crucial to achieving the broad community acceptance of Anthropogenic Global Warming necessary to address it's causes and it's mitigation effectively. There appears to be a broad a range of views on the issue amongst religious people, from accepting the mainstream science through to vigorous condemnation of it as a kind of green religion and something inspired by Satan. I'm doubtful that the latter will be open to reason but there must be a lot who currently disbelieve the science that can be reached, perhaps by other means. How? I had wondered if restating things in terms of religious symbolism might cause some to reassess; the brimstone stinking coal and it's gases, dug up from the deep bowels of the earth, that burns with a terrible heat and stench can be - for a time - a key to wealth and power beyond all prior imagination, not to mention power great engines of war for smiting enemies with destructive force never before known. But there is a catch with a cost; for every portion burned for momentary benefit the heat transferred to the world at large will be magnified a hundedfold, to persist for tens of generations. It's a bargain with the devil, where the glittering prize entices people to ignore the fine print. ("Now hang on a minute - what was that bit you just said?" "You mean about the world getting irrevocably hotter and more hellish? Don't worry - the planet is huge. All the navvies with all the shovels in the world couldn't dig up and burn enough to make the world noticeably hotter! Even Arrhenius could tell you that!" "No, not that - tell more about the wealth and power and great engines of war for smiting enemies!"). Perhaps God buried so much of the stuff deep underground to prevent its excessive use, yet with enough near the surface as a temptation and test of moderation. Certainly there were religious people near the beginnings of the Industrial Revolution that vehemently opposed the use of coal, although for it's stink and health effects when burned inefficiently and close by as household fuel. That style of rhetoric means saying some stuff I don't actually believe - me seriously doubting the existence of God or Satan - even if there are rhetorical means that allow me to do so (like this) whilst making it clear I'm not being literal; yet I think that kind of symbolistic framing does still embody a lot of truth. If attempts at reason with people who believe only God can change the climate or that climate science is part of a new "green" paganism or The Devil's work, is it ethical to put it to them in such terms? I believe the real issues are ethical ones and as far as I can see the vast majority of religious people do perceive their religious teachings and beliefs as ethical. They can often be as well informed as people who are not religious and we do see religious leaders and movements that see it as a matter of intergeneration ethics to act on emissions. Others may see the benefits of fossil fuels in terms of prosperity and reduction of human suffering with the conclusion that to deny humanity these "God given gifts" would increase human suffering. I think they are failing to consider harms that are not immediately and visibly apparent, but I think many of those can, in theory, be persuaded that those harms do exist and that it is, in the longer term, a poor exchange. But it is those who do not accept the science that most need to be spoken to in terms they understand to be persuaded - persuaded that it is a true problem that is only unlike that of any other problem of dealing with consequences of human action that we have to live with in it's scale and duration. In some senses the problem can be described as Biblical in it's scale; I don't altogether understand why a large bloc of religious people reject that the (God given) gifts of observation and reason could be essential to proving humankind capable and trustworthy as custodians of this world, but it could be the kinds of reasons and reasoning being used that prevents effective engagement. I think the climate problem (and other great challenges with living within a finite world) can be understood broadly as a great, inevitable and unavoidable test, not only of the ethics of individual behaviour, but the worthiness of our collective behaviour via our institutions and organisations - and with the one interdependent with the other. It requires ethics to be applied beyond that of individuals and over timespans much greater than the lifespan of individuals. I don't think it takes religious belief to perceive our ability to live within the limits of this world as an unavoidable test of our collective intelligence and inventiveness, of our institutions and our systems of regulation as well as our individual and collective ethics; this is something where I think religious belief and science based understanding not only can find common ground, but where it's essential that we do so. (Minor edits done for grammar and clarity)

The Little Ice Age and solar Maunder Minimum are key pieces of "It's the sun not CO2" climate science disagreeing. Otherwise they would be just small components of natural climate variation with no special standout significance. The argument goes that the low solar activity of the Maunder Minimum must have caused the Little Ice Age and if solar activity has that much influence then the increase in solar activity after then, and especially during the 20th century, can explain global warming without involving CO2. With solar activity heading in a period of decline, a bit like the Maunder Minimum, then we should expect another little ice age and the end of global warming. Some serious issues with that are - it involves unexplained, unsupported blanket dismissal of the science supporting the significant role of greenhouse gases: it fails to look at what else was going on around that time that could provide alternate causation for the little ice age like volcanic activity ( http://www.livescience.com/18205-ice-age-volcanoes-sea-ice.html ) and AMOC (Atlantic Meridional Overturning Circulation aka Gulf Stream) slowdown: recent revision of historic sunspot data that are the proxy evidence of solar activity changes used - revision done independent of climate science by solar specialists to reconcile different sunspot counts of different historic methodologies - means estimates of increased solar activity over the 20th century is not so clear and the correlation with warming breaks down ( http://www.nature.com/news/spotty-sunspot-record-gets-a-makeover-1.18145 ): and recent low solar activity has not resulted in any slowdown of global warming, with the short term variability - mostly El Niño Southern Oscillation - that tended to mask warming in the surface air temperatures during the first part of this century now being followed by variability that is taking temperatures back to and above the longer term trend and into record territory. With Little Ice Age causes other than solar activity - multiple volcanic eruptions over a few decades triggering ice and snow cover changes that persisted (global cooling from single eruptions normally gone within a couple of years) - the key basis for claiming global warming is primarily natural and sun caused breaks down. In one of those curious coincidences one of the counter intuitive outcomes of warming that is possible (but not considered likely) is a sudden shutdown of AMOC with consequences that would look quite similar to the "new little ice age" the sun not CO2 proponents are predicting for their new solar Maunder Minimum - influx of freshwater from Greenland and other glacial melt as well as expected increase in rainfall in some neighbouring regions from warming flows into the Nth Atlantic prevents the sinking from getting cold that carries Gulf Stream water deep and helps sustain that ocean circulation. ( http://www.nature.com/articles/srep14877 ) The flow of warm water that makes Europe's climate warmer than other regions at that latitude stops and significant cooling happens, which can widely affect global temperature and could persist for several decades before warming overwhelms that effect. Interesting that slowdown of AMOC is currently occurring and is implicated in the persistent cool spot in the Nth Atlantic - which in turn is implicated in recent decade of extreme and unusual weather in surrounding regions like Nth America and Europe. PS - linking option (along with that whole tool bar) never appeared - perhaps because I'm using (much disliked) iPad? - so links are inserted directly but less neatly.

An actual feasible means of doing so would be better than mildly interesting and I suppose if somehow it was relatively quick and easy to visit other stars it would get a lot more interesting. I have yet to see any proposals that are feasible and many, like your equatorial slingshot, don't offer anything practical. I remain dubious that, in the absence of a quick and easy (relatively speaking) means, there is any compelling reason to go interstellar. Scientific curiosity is in my opinion worthwhile but I don't accept that interstellar colonisation is - projects of that scale run on expectations of tangible returns and historically, successful colonies had a sound economic basis, as well as proceeding on the back of existing, economically viable technologies - not built from scratch. Curiosity - and I suppose vanity/PR projects for morale and inspirition - can be indulged when it doesn't cost too much, but as things stand interstellar travel is such a long shot that it has to be reasonably classed as impossible. Aiming high is fine and good, but exploring possibilities for doing the impossible should not divert significant resources from goals more immediate and compelling. As long as it remains extraordinarily difficult and expensive and/or likely to take longer than human civilisation has so far existed to get there then practical priority means those resources should be put to use nearer to our home world.

The price of building those bridges, with or without PV or wind turbines to supply power, would add something to the costs too I would imagine1 As a thought experiment it's mildly interesting. As a physics exam question - how much energy to reach x% of c, what centripetal acceleration - it may have some application. I'm not convinced interstellar travel is a reasonable goal, let alone an achievable one for a human civilisation, even if it makes for engaging fiction.

I believe the short term behaviour - that sinking of the more dense gas as it is released into air - is called a "bulk phase effect" and happens because it is not yet well mixed and there is a significant difference in gas density between it and surrounding air. What will happen is that it will mix and be dispersed, even from the bottom of a deep open topped container. Even in the absence of any mixing from large scale air movements (wind, convection), mixing will happen because of "diffusion" and diffusion happens because molecules of gases are always in motion - called Brownian motion - and for CO2 at 15 degrees C for example, the molecules are moving at about 400 metres per second; 1 gee of gravity (9.8m/sec*2) is not enough to make much difference to that motion compared to that of the other lighter and faster moving molecules like N2 and O2. Very high gravity/centrifuging or very cold temperatures would be needed to overcome that mixing effect of Brownian motion of gas molecules.

B. John Jones - I think you have a view of how science reaches consensus/agreement that is based on assumptions that have little or no foundation, that have nothing to do with how science really reaches consensus. Perhaps you have been told that agreement comes via compulsion by threat of expulsion but you have not shown evidence that that is the case or even appear willing to consider that such a view could be incorrect. Perhaps there are issues within science that conflict with your religious beliefs, beliefs that are accepted as self evidently true within "religious communities" with similar beliefs that are "minority" opinion and rejected within scientific ones. But these will rarely be cases of rejection for being in disagreement with majority of expert opinion but because the observation, data, experimental results and logical basis fail to support them. Persistence in the face of such criticisms can, unfortunately, provoke derision - which, when seen without the context (of the details of the critique, pointing out logical flaws etc) can be mistaken for a kind of tribalistic expulsion by a "scientific community". And not all who do the derision and agree with the mainstream scientific understanding on a subject are scientists or even necessarily well informed themselves. I suppose, despite my efforts to be well informed on issues of interest to me I am more an enthusiastic fan and defender of science without being a scientist; given the Internet anyone can appoint themselves a critic or claim expertise; in my experience taking those discussions to those who can legitimately claim expertise will see me corrected without mercy when I have the facts wrong. Taking them preferentially to those without expertise and ignoring or avoiding those with it will tend to reinforce views that may have little or no scientific basis. Those who hold particular views that are rejected by science and cannot or will not engage with the detail of criticism and reasons for rejection may easily conclude that it is unreasonable and unfair or even an attack on their beliefs or selves by people with different ones, but that would not be correct; the mainstream, consensus, established scientific understandings did not arise out of belief but from a preponderance of evidence within a framework that holds honesty and accuracy, backed by thorough record keeping (to perpetually allow conclusions to be subject to review and revision) - even if for those without expertise it may appear to be "just" a personal belief. (Minor edit done for clarity)

I think science is unified in motivation of science practitioners to achieve a better understanding of our world on the basis of what is supported by evidence and reason. It is unified by long standing practices of institutions, the application of high professional standards and open, accurate and honest record keeping. Depending on the specific subject there can be strong disagreements but the trend is towards consensus as the depth of knowledge grows and inadequacies of data and reasoning are overcome. Whilst counter examples can be found, most scientists are willing to let go of their conclusions in the face of contrary evidence and improved methodology.