Check out the last graph in the original paper. It shows (pay attention to the axes) that the Central Pacific island chains studied, as a group, increased significantly in land area.
However, the Solomon Islands, specifically, may be an exception to that. (I'd need the raw data to tell for sure; the net change is close enough to zero that I can't just eyeball it from the graph.)
In any case, the specific islands which are the main focus of the paper were all tiny (the largest was only 0.25 (km)^2) and not at all representative of the Solomon Islands as a whole. They were selected for further scrutiny specifically because they were eroding quickly; in a chain with hundreds of islands, there were bound to be at least a few getting smaller.
I have now read the entire paper. It is true that it does not ever directly attribute the sea level rise in the Solomon Islands to AGW. (The linked ABC news article does though - surely the scientists will be publicly denouncing the media's gross distortion of their claims any minute now... ?)
On the other hand, the premise of the paper is that sea level rise is responsible for significant loss of land area in the Solomon Islands (and the authors worked very hard to connect sea level rise to AGW at every opportunity, even though they didn't quite come out and say that AGW has actually caused any sea level rise yet).
That's a problem, because nowhere in their paper (that I could find, anyway) do they actually offer any evidence that the local sea level rise experienced by the Solomon Islands contributed meaningfully to the loss. They point out several other factors that likely dominated, one of which was erosion by wave action. They then attempt to connect this back to AGW with the following statement:
Wave energy can interact synergistically with localised sea-level rise (through changing wave refraction dynamics and more wave energy propagating across reef crest onto the coast) to exacerbate coastal erosion (Storlazzi et al 2015) and thus may be a key driver of the rapid coastal recession in the Solomon Islands. Further work is required to determine the relative importance of extreme wave events or incremental changes in incident wave energy and their interactions with sea-level on shoreline dynamics of islands.
Notice the operative words there: "can", "may be", and "further work is required". They don't actually have anything to say on the subject - that is, on the causal connection between sea level rise and increased wave erosion - other than "maybe you should read these other guys' papers" and "give us money and we'll write something too". But, they decided to name their paper after it anyway, and the media ran with it.
The main actual content of the study - once all of the background material and discussion is filtered out - is basically just:
1) Some statistics about the rates of erosion and accretion on various islands in the Central Pacific, including the Solomon Islands.
2) More statistics about the atmospheric and oceanic conditions over time around those islands - much of which was extrapolated, not measured.
3) A few anecdotes about communities that need to relocate - all of whom, from the sound of it, were in poor locations to begin with.
As someone else pointed out, the last graph clearly shows (if you know how to read the axes, anyway), that there was a net increase in land area for the islands chains studied; the authors simply chose to focus upon a specific few tiny islands that shrank.
"Of the order" is a science/engineering term meaning "very roughly", within a factor of two to ten (depending on the context). I was just too lazy to go look up the actual numbers, so thanks for the link.
It looks like the actual range is 0-16 meters depending on the location, but with most beaches being very much at the lower end of that range.
Unfortunately it seems like there are lies and deception and agendas on both sides of the AGW issue.
This is true. In the absence of clarity though, I think the sensible thing is not to panic, discard the foundation of the world's energy economy, and cede power to a global government. That may just be me, though.
Hopefully renewables and/or nuclear (fission or fusion) will eventually get good enough (actually good enough, without excessive subsidies) that people won't want to mess around with fossil fuels, and then we can put the whole argument to rest.
The post you replied to is addressing claims that AGW-induced sea level rise is already causing significant damage, which is clearly bogus. One of the reasons I am sceptical of the claims of sea level doom, is the fact that its prophets seem incapable of distinguishing clearly between predictions about the future, and present reality.
That is not a joke: it's a real, peer reviewed scientific paper.
And there are other "real, peer reviewed scientific paper"s that say the number will be more like 2 meters. Almost as if the science is not settled...
Moreover, all of the catastrophic sea level prophecies depend upon the larger anthropogenic global warming theory, which has several problems:
1) It's predictive record is very poor; numerous specific claims from prominent individuals and organizations have already been falsified by the passage of time. We have already overshot some of the worst-case CO2 emission predictions from early in the movement, and yet we have alsoundershot some of the best-case temperature predictions, suggesting that the climate's sensitivity to additional CO2 is far lower than claimed. The AGW movement has quietly adjusted their predicted temperature rise downward quite substantially, while still maintaining that the situation is as dangerous as ever.
2) The models are extremely vague, imprecise, and mutually contradictory. The only specific thing they seem to agree on, is that we're doomed.:eyeroll:
3) The data with which the models are calibrated is of very low quality; the error bars are huge on almost everything, especially prior to about 1990 (or 2000?) when modern sensor networks started coming online. Definitive claims are frequently made about time periods for which we have no solid data at all, and the past data that we do have is constantly being "adjusted" and "corrected" - conveniently, usually in a direction that magnifies any upward temperature trends.
4) We've already passed several of the drop-dead dates set by the AGW prophets - the "If you don't act by XXXX, it will be too late!" dates. But of course they just set new ones and pretend like the last round never happened...
(Yes, there are sources for all of the above. But it's exhausting to compile all the links to the standards required by internet critics, so I'm not going to do it right now. Maybe later if someone asks, but really - it's not that hard to Google it if you really care - you just have to be willing to read the heretical websites of the dreaded "climate deniers" like WattsUpWithThat.com, who will in turn link you back to the relevant government, peer-reviewed, and mainstream media sources if you look hard enough.)
Finally, even if it really happens, a seven meter sea level rise over the course of a century or so obviously will not "doom" us. The vast majority of land on Earth is at a much higher elevation than that. Some specific areas (like Florida) would be hit pretty hard, but the predicted rise is still slow enough to give people plenty of time to relocate further inland/uphill if required. It would be expensive - but so would giving up all fossil fuels.
"Bold-faced lie" is also an English idiom, albeit likely of more recent origin.
Also, since the phrase makes sense by itself, even without having heard it before, it is a valid, meaningful English phrase even if you refuse to acknowledge idioms coined after [insert arbitrary date here].
The point is, that if the land was at such low elevation, or so fragile, that it could be submerged or destroyed by a tiny rise in sea level (probably more like 2 cm, than 25 cm), there is no way that anyone can assert a definitive cause-and-effect relationship between CO2 emissions and the islands disappearing. There is a high probability that it was going to disappear anyway, even without the extra 2 (or if you insist, 25) cm.
They are claiming that it got eroded, and that it wouldn't have if the sea level were a tiny bit lower. There is no way they can know that, especially since the actual sea level rise-to-date which is possibly attributable to AGW is more like 2 cm, not 25 cm.
This is a separate effect from your silly claim of a lie.
The statement in the summary, at least, is a lie because they are asserting a definitive cause-and-effect relationship where there is - at best - an unprovable possibility of one, rather than actual solid evidence for one. The claim is being sensationalized.
Did you look at the EPA graph? I'm being waaaaayyyy too generous when I make it sound like AGW sea level rise-to-date could be as much as 25 cm.
The rate of rise was astonishingly constant from the beginning of the record in 1880 (allegedly ~70 years before man-made warming became meaningful), up until about 2000.
There is a small bump at the end representing approximately the last seven years. The size of that bump? About 2 cm. (Also, the bump is shrinking now and was never there to begin with in the satellite record; it's only present in the tide gauge data. There's a good chance it's just noise.)
The average annual sea level rise prior to the bump was about 0.15 cm, meaning that the bump accelerated the inevitable natural end of the "islands" by less than twenty years, even if you want to blame a non-linear increase in wave erosion. Colour me unimpressed, seeing as real islands generally don't have expiration dates that are humanly relevant, at all.
...five of the Solomon Islands have completely submerged underwater due to man-made climate change...
That's a bold-faced lie. The total global sea level rise since 1880 is less than 25 cm (10 inches), according to the EPA. The natural tidal range of the oceans is of the order of one metre (several feet). Any island that has "submerged" during that time period did so primarily because of other factors, such as the ground subsiding, or erosion driven by the wind and the waves.
This is especially obvious when you consider that anthropogenic global warming is not believed to have reached significant levels until around 1950 (if then).
As for houses washing away and such - any land that can be "submerged" solely by a sea level change of 25 cm was already getting scoured regularly by waves, storm surges, etc.
can the beam be held on a spot long enough to matter may be the trick
Yes it's hard to believe they can aim that quickly and precisely - but then, it's such an obvious and fundamental problem that the answer must surely be, "Yes"; otherwise why even bother? Based on the capabilities of the cancelled (but successfully tested) THEL project, I think this problem has been solved since the early 2000s, if not earlier.
If the target has to keep jinking to avoid laser lock, he's not going to be able to use guns or lock missiles.
It's quite plausible that the main battlefield impact of early laser weapons will simply be to force tactical changes on the enemy: fight in cloudy/foggy/smoky conditions whenever possible, always attack in sufficient numbers (of vehicles, or of individual missiles/shells/etc.) to overwhelm the capacity of the laser defences, etc.
However, I expect that if the early laser weapons are at all successful, research and development of higher power levels will be a high priority. At some point, the only effective strategic defence will be to have your own laser weapons. When the enemy has (for example) 10 MW orbital lasers, the only effective defence will be to have a laser of your own to shoot back with.
I don't expect lasers to actually replace or obsolete missiles and guns, but everyone will need "laser fire support" to be able to maintain the tactical conditions necessary to effectively employ missiles and guns - kind of like the way aircraft haven't replaced ground vehicles, but your ground vehicles probably won't last very long if the other guy has air support, and you don't.
And therefore, the GM Sunraycer is proof that the Tesla Model S is not possible. I understand.
"A straw man argument is one that misrepresents a position in order to make it appear weaker than it actually is, refutes this misrepresentation of the position, and then concludes that the real position has been refuted. This, of course, is a fallacy, because the position that has been claimed to be refuted is different to that which has actually been refuted; the real target of the argument is untouched by it." Straw Man Fallacy
I gave a specific mathematical argument as to why a solar-powered AIRPLANE is an inherently bad idea. Cars are not airplanes. Moreover, the Tesla Model S is NOT SOLAR-POWERED; it is battery powered. I have already stated that a useful battery-powered airplane could plausibly be developed in the future.
More generally, you are falsely accusing me of saying, "because this technology is bad today, therefore it always will be." But, what I actually said is, "there are basic scientific reasons why this technology is bad, and probably always will be." If you don't understand the difference between those two statements, then you have no understanding of how science and engineering work.
Although imagine the surface area and power requirements of something like this [shiply.com].
Many other people in this discussion have already suggested solar-powered airships, and I already replied to a couple of them agreeing that the idea has some potential. Nevertheless, airships are not airplanes, and will never compete in the same markets as a Cessna 188. (They could overlap a little with the Boeing 747, but not that much.)
The point I'm trying to make is that it's a stupid argument to say that the Solar Impulse 2 is not a drop-in replacement for any existing aircraft. It is a technology demonstrator.
And the point which I made rather clearly in my original post, was that the inadequacy of the Solar Impulse 2 is not due to technological immaturity, but rather due to fundamental physics that are unlikely to ever be overcome, no matter how much money and time is spent trying.
Of course it's not going to replace anything. It's going to advance the state of the art though, and it's going to bring about additional research and investment into related technologies in various applications.
No doubt. When did I ever suggest otherwise? That's not the subject of the article, though.
Laser far too easy to counter. Smoke and larger air particles can counter for ground troops.
A cloud of particulates will also (temporarily) blind the troops trying to hide inside it, reducing their situational awareness and ability to fight back. This could be beneficial to the attacker in the same way that machine guns are used to "suppress" enemy soldiers - forcing them to duck for cover has tactical utility even if you don't actually manage to hit any of them.
For missiles, drones, and airplanes simply roll or make the exterior 'wiggle'.
Just "wiggling" is probably not good enough; all the attacker has to do is target a part of the plane that remains in his line of sight throughout the whole of (or at least most of) the motion. The laser hits at the speed of light, so it's not like you're going to be able to jink fast enough to actually be untargetable.
A fast roll can help - if the defender could actually withstand the G-forces and (in the case of a manned plane) nausea. Even then, though, it's guaranteed to increase the required dwell time by about a factor of three. I expect that this method is only really useful for missiles; planes (manned or otherwise) are just too big to roll fast enough.
But a rail gun with say a varying 1-16 mj esp with smart ammo, is going to produce hits regardless of counter measures.
Perhaps. I don't think effective railguns will be miniaturized enough to stick on a fighter jet any time soon though. Maybe it would work on a large bomber or cargo plane, though?
To output 1MJ in a single second, I multiplied that by 3600 => 1 MW of power is needed.
By definition, a Watt is 1 Joule per second.
A 16.6 kW laser would need a minute, so if these guys don't mind flying in circles for a minute with their lasers on, they're probably good.
The question is, can you continuously illuminate the same small spot on a rapidly moving, distant target for a minute?
How are they doing regarding portable nuclear power stations that can fit into planes?
Actually, even a full 1 MW isn't an unreasonable amount of power to siphon off the main turbine(s) on a jet fighter: the shaft power on each engine is measured in 10s of MW. The additional mass of the required alternator, wiring, cooling, etc. would likely be substantial, though.
A one-second pulse that could slice 38x10x1mm in steel could probably do 10 to 100 times that in aluminum skin...
I was curious, so I took a stab at calculating how much easier aluminium is to melt than steel:
[room temperature] = [273 K] [heat capacity by mass] = [molar heat capacity] / [atomic mass] [heat of fusion by mass] = [molar heat of fusion] / [atomic mass] [melting energy by mass] = ([melting point] - [room temperature]) * [heat capacity by mass] + [heat of fusion by mass] [melting energy by volume] = [melting energy by mass] / [density]
For Fe (Iron): [density] = [7.87 g/cm^3] [atomic mass] = [55.8 g/mol] [molar heat capacity] = [25.1 J/(mol*K)] [melting point] = [1811 K] [molar heat of fusion] = [13.8 kJ/mol]
[heat capacity by mass] = [25.1 J/(mol*K)] / [55.8 g/mol] = [0.450 J/(g*K)] [heat of fusion by mass] = [13.8 kJ/mol] / [55.8 g/mol] = [247 J/g] [melting energy by mass] = ([1811 K] - [273 K]) * [0.450 J/(g*K)] + [247 J/g] = [939 J/g] [melting energy by volume] = [939 J/g] * [7.87 g/cm^3] = [7.39 kJ/cm^3]
For Al (Aluminium): [density] = [2.70 g/cm^3] [atomic mass] = [27.0 g/mol] [molar heat capacity] = [24.2 J/(mol*K)] [melting point] = [933 K] [molar heat of fusion] = [10.7 kJ/mol]
[heat capacity by mass] = [24.2 J/(mol*K)] / [27.0 g/mol] = [0.896 J/(g*K)] [heat of fusion by mass] = [10.7 kJ/mol] / [27.0 g/mol] = [396 J/g] [melting energy by mass] = ([933 K] - [273 K]) * [0.896 J/(g*K)] + [396 J/g] = [987 J/g] [melting energy by volume] = [987 J/g] * [2.70 g/cm^3] = [2.66 kJ/cm^3]
Assuming that only melting is required, it appears that Aluminium is only 3x easier to cut than steel. (If you really want to drill a deep hole in metal fast, it becomes necessary to actually boil it. But, I suspect that takes more power density than a 100 KW laser is likely to achieve against a fast-moving target at long distance.)
If you use solar power to produce the fuel, doesn't that mean that the 747 is entirely solar powered?
You can call that a solar-powered 747, if you're willing to let Tesla drivers who live near a fission power plant say that they drive an "atomic car".
More seriously, though: yes, of course, solar energy can be used indirectly to power airplanes - as can hydroelectric, wind, nuclear, etc. But, that's not really the topic we were discussing.
Do you understand why the Solar Impluse 2 looks like it does? I do.
Solar planes need a huge wingspan both to provide surface area on which to mount photovoltaic cells, and also in order to achieve the excellent lift-to-drag ratio required to fly with so little power available. Future improvements in solar cell efficiency, battery energy density, etc. could plausibly cut the wingspan in half (down to 737 size), but it would still be huge, slow, and fragile.
Unless you think solar cells can be built with greater than 100% efficiency, it's just not reasonable to expect much more than that, for reasons of basic physics which I already outlined in my original post.
Ah. Because any future solar-powered plane will necessarily look just like Solar Impulse 2. Got it.
Solar-powered airships have some potential. The square-cube law could be a problem though: airships generally need to be extremely large in order to be efficient, but you can't make it too big if you want to use solar power, because the mass of the ship grows faster than its surface area.
A battery-powered direct replacement is theoretically possible, but unlikely. The reason that hydrocarbons have such phenomenal energy density (for a chemical source, anyway), is that because of Earth's oxygen atmosphere, you don't have to carry 75+% of the required mass of reactants with you.
Batteries, on the other hand, force you to carry the oxidizer, which makes them quite heavy, even if the main chemical reaction is just as energetic as burning hydrocarbons. Fuel cells are the only battery-like option that I'm aware of that avoids this problem, but they still run on hydrocarbons. Metal-air batteries look good, until you realize that they actually get heavier as the flight progresses...
With major advances, battery power could work for short hops and/or low speeds, but it will probably never be viable for long-distance, high-speed manned flight.
Or if all else fails, just develop jet engines that run on biofuel and run the farming equipment on batteries.
Biofuel or synthetic fuel is a far more sensible power source for planes.
Synthetic fuels are a sensible idea. I would not call that a "solar-powered" plane though, for the same reason that I won't call a Tesla Model S a "methane-powered car", even if that's what your local grid power plant is burning.
Honestly... not really. Fuel is only about half the mass of a long-range hydrocarbon plane at take-off.
Not being able to dump spent batteries during the flight only increases the average mass of the plane over the course of the flight by about 30%, which isn't really that big of a deal compared to the more basic problem that current batteries weigh 40x as much as jet fuel for the same energy. The extra 30% is just a rounding error, in comparison.
The solar demonstrator plane in the article can only carry a single person, and yet, in order to fly, it requires the wingspan of a 747 (among the largest aircraft ever built). It's already far too wide to operate from most airports.
You want to take that plane - which can barely accommodate a single pilot - and weigh it down with multiple passengers, flight attendants, and amenities? You must be joking.
Remember, not everyone needs to get from Dallas to Tokyo in under 6 hours. The slower, cheaper, and more amenity rich trip on a properly considered PV powered flight are for people who want to get from A to B as part of a deadline relaxed vacation.
Those people who are not in a hurry will take trains or cruise ships, both of which actually exist today, and still work just fine even after being weighed down with attendants and amenities. Or - if you insist on air travel - perhaps an airship like vtcodger suggested above.
Namely, the 737 is designed with [...] big assed engines that produce lots of thrust on what is otherwise a ballistically propelled brick with aerofoil control surfaces.
1) Do you really not know the difference between the 737, and the 747 I was actually talking about in the post you replied to?
2) If you think either of those planes is "a ballistically propelled brick", you know nothing about aerodynamics.
Slashdot Mirror
Check out the last graph in the original paper. It shows (pay attention to the axes) that the Central Pacific island chains studied, as a group, increased significantly in land area.
However, the Solomon Islands, specifically, may be an exception to that. (I'd need the raw data to tell for sure; the net change is close enough to zero that I can't just eyeball it from the graph.)
In any case, the specific islands which are the main focus of the paper were all tiny (the largest was only 0.25 (km)^2) and not at all representative of the Solomon Islands as a whole. They were selected for further scrutiny specifically because they were eroding quickly; in a chain with hundreds of islands, there were bound to be at least a few getting smaller.
True - it is a non-falsifiable hypothesis, since every time another "point of no return" prediction fails, they reschedule it another 5-20 years out.
I have now read the entire paper. It is true that it does not ever directly attribute the sea level rise in the Solomon Islands to AGW. (The linked ABC news article does though - surely the scientists will be publicly denouncing the media's gross distortion of their claims any minute now... ?)
On the other hand, the premise of the paper is that sea level rise is responsible for significant loss of land area in the Solomon Islands (and the authors worked very hard to connect sea level rise to AGW at every opportunity, even though they didn't quite come out and say that AGW has actually caused any sea level rise yet).
That's a problem, because nowhere in their paper (that I could find, anyway) do they actually offer any evidence that the local sea level rise experienced by the Solomon Islands contributed meaningfully to the loss. They point out several other factors that likely dominated, one of which was erosion by wave action. They then attempt to connect this back to AGW with the following statement:
Wave energy can interact synergistically with localised sea-level rise (through changing wave refraction dynamics and more wave energy propagating across reef crest onto the coast) to exacerbate coastal erosion (Storlazzi et al 2015) and thus may be a key driver of the rapid coastal recession in the Solomon Islands. Further work is required to determine the relative importance of extreme wave events or incremental changes in incident wave energy and their interactions with sea-level on shoreline dynamics of islands.
Notice the operative words there: "can", "may be", and "further work is required". They don't actually have anything to say on the subject - that is, on the causal connection between sea level rise and increased wave erosion - other than "maybe you should read these other guys' papers" and "give us money and we'll write something too". But, they decided to name their paper after it anyway, and the media ran with it.
The main actual content of the study - once all of the background material and discussion is filtered out - is basically just:
1) Some statistics about the rates of erosion and accretion on various islands in the Central Pacific, including the Solomon Islands.
2) More statistics about the atmospheric and oceanic conditions over time around those islands - much of which was extrapolated, not measured.
3) A few anecdotes about communities that need to relocate - all of whom, from the sound of it, were in poor locations to begin with.
As someone else pointed out, the last graph clearly shows (if you know how to read the axes, anyway), that there was a net increase in land area for the islands chains studied; the authors simply chose to focus upon a specific few tiny islands that shrank.
"Of the order" is a science/engineering term meaning "very roughly", within a factor of two to ten (depending on the context). I was just too lazy to go look up the actual numbers, so thanks for the link.
It looks like the actual range is 0-16 meters depending on the location, but with most beaches being very much at the lower end of that range.
Unfortunately it seems like there are lies and deception and agendas on both sides of the AGW issue.
This is true. In the absence of clarity though, I think the sensible thing is not to panic, discard the foundation of the world's energy economy, and cede power to a global government. That may just be me, though.
Hopefully renewables and/or nuclear (fission or fusion) will eventually get good enough (actually good enough, without excessive subsidies) that people won't want to mess around with fossil fuels, and then we can put the whole argument to rest.
The post you replied to is addressing claims that AGW-induced sea level rise is already causing significant damage, which is clearly bogus. One of the reasons I am sceptical of the claims of sea level doom, is the fact that its prophets seem incapable of distinguishing clearly between predictions about the future, and present reality.
That is not a joke: it's a real, peer reviewed scientific paper.
And there are other "real, peer reviewed scientific paper"s that say the number will be more like 2 meters. Almost as if the science is not settled...
Moreover, all of the catastrophic sea level prophecies depend upon the larger anthropogenic global warming theory, which has several problems:
1) It's predictive record is very poor; numerous specific claims from prominent individuals and organizations have already been falsified by the passage of time. We have already overshot some of the worst-case CO2 emission predictions from early in the movement, and yet we have also undershot some of the best-case temperature predictions, suggesting that the climate's sensitivity to additional CO2 is far lower than claimed. The AGW movement has quietly adjusted their predicted temperature rise downward quite substantially, while still maintaining that the situation is as dangerous as ever.
2) The models are extremely vague, imprecise, and mutually contradictory. The only specific thing they seem to agree on, is that we're doomed. :eyeroll:
3) The data with which the models are calibrated is of very low quality; the error bars are huge on almost everything, especially prior to about 1990 (or 2000?) when modern sensor networks started coming online. Definitive claims are frequently made about time periods for which we have no solid data at all, and the past data that we do have is constantly being "adjusted" and "corrected" - conveniently, usually in a direction that magnifies any upward temperature trends.
4) We've already passed several of the drop-dead dates set by the AGW prophets - the "If you don't act by XXXX, it will be too late!" dates. But of course they just set new ones and pretend like the last round never happened...
(Yes, there are sources for all of the above. But it's exhausting to compile all the links to the standards required by internet critics, so I'm not going to do it right now. Maybe later if someone asks, but really - it's not that hard to Google it if you really care - you just have to be willing to read the heretical websites of the dreaded "climate deniers" like WattsUpWithThat.com, who will in turn link you back to the relevant government, peer-reviewed, and mainstream media sources if you look hard enough.)
Finally, even if it really happens, a seven meter sea level rise over the course of a century or so obviously will not "doom" us. The vast majority of land on Earth is at a much higher elevation than that. Some specific areas (like Florida) would be hit pretty hard, but the predicted rise is still slow enough to give people plenty of time to relocate further inland/uphill if required. It would be expensive - but so would giving up all fossil fuels.
Sorry, I forgot the post I linked doesn't include the link to the EPA graph which is my actual source: https://www3.epa.gov/climatechange/science/indicators/oceans/sea-level.html
Unless it's at least 10m above sea level, it was always a dumb place to build anything you don't want to get wet. Hurricanes are not new...
"Bold-faced lie" is also an English idiom, albeit likely of more recent origin.
Also, since the phrase makes sense by itself, even without having heard it before, it is a valid, meaningful English phrase even if you refuse to acknowledge idioms coined after [insert arbitrary date here].
The point is, that if the land was at such low elevation, or so fragile, that it could be submerged or destroyed by a tiny rise in sea level (probably more like 2 cm, than 25 cm), there is no way that anyone can assert a definitive cause-and-effect relationship between CO2 emissions and the islands disappearing. There is a high probability that it was going to disappear anyway, even without the extra 2 (or if you insist, 25) cm.
They are claiming that it got eroded, and that it wouldn't have if the sea level were a tiny bit lower. There is no way they can know that, especially since the actual sea level rise-to-date which is possibly attributable to AGW is more like 2 cm, not 25 cm.
This is a separate effect from your silly claim of a lie.
The statement in the summary, at least, is a lie because they are asserting a definitive cause-and-effect relationship where there is - at best - an unprovable possibility of one, rather than actual solid evidence for one. The claim is being sensationalized.
Did you look at the EPA graph? I'm being waaaaayyyy too generous when I make it sound like AGW sea level rise-to-date could be as much as 25 cm.
The rate of rise was astonishingly constant from the beginning of the record in 1880 (allegedly ~70 years before man-made warming became meaningful), up until about 2000.
There is a small bump at the end representing approximately the last seven years. The size of that bump? About 2 cm. (Also, the bump is shrinking now and was never there to begin with in the satellite record; it's only present in the tide gauge data. There's a good chance it's just noise.)
The average annual sea level rise prior to the bump was about 0.15 cm, meaning that the bump accelerated the inevitable natural end of the "islands" by less than twenty years, even if you want to blame a non-linear increase in wave erosion. Colour me unimpressed, seeing as real islands generally don't have expiration dates that are humanly relevant, at all.
...five of the Solomon Islands have completely submerged underwater due to man-made climate change...
That's a bold-faced lie. The total global sea level rise since 1880 is less than 25 cm (10 inches), according to the EPA. The natural tidal range of the oceans is of the order of one metre (several feet). Any island that has "submerged" during that time period did so primarily because of other factors, such as the ground subsiding, or erosion driven by the wind and the waves.
This is especially obvious when you consider that anthropogenic global warming is not believed to have reached significant levels until around 1950 (if then).
As for houses washing away and such - any land that can be "submerged" solely by a sea level change of 25 cm was already getting scoured regularly by waves, storm surges, etc.
can the beam be held on a spot long enough to matter may be the trick
Yes it's hard to believe they can aim that quickly and precisely - but then, it's such an obvious and fundamental problem that the answer must surely be, "Yes"; otherwise why even bother? Based on the capabilities of the cancelled (but successfully tested) THEL project, I think this problem has been solved since the early 2000s, if not earlier.
If the target has to keep jinking to avoid laser lock, he's not going to be able to use guns or lock missiles.
It's quite plausible that the main battlefield impact of early laser weapons will simply be to force tactical changes on the enemy: fight in cloudy/foggy/smoky conditions whenever possible, always attack in sufficient numbers (of vehicles, or of individual missiles/shells/etc.) to overwhelm the capacity of the laser defences, etc.
However, I expect that if the early laser weapons are at all successful, research and development of higher power levels will be a high priority. At some point, the only effective strategic defence will be to have your own laser weapons. When the enemy has (for example) 10 MW orbital lasers, the only effective defence will be to have a laser of your own to shoot back with.
I don't expect lasers to actually replace or obsolete missiles and guns, but everyone will need "laser fire support" to be able to maintain the tactical conditions necessary to effectively employ missiles and guns - kind of like the way aircraft haven't replaced ground vehicles, but your ground vehicles probably won't last very long if the other guy has air support, and you don't.
And therefore, the GM Sunraycer is proof that the Tesla Model S is not possible. I understand.
"A straw man argument is one that misrepresents a position in order to make it appear weaker than it actually is, refutes this misrepresentation of the position, and then concludes that the real position has been refuted. This, of course, is a fallacy, because the position that has been claimed to be refuted is different to that which has actually been refuted; the real target of the argument is untouched by it."
Straw Man Fallacy
I gave a specific mathematical argument as to why a solar-powered AIRPLANE is an inherently bad idea. Cars are not airplanes. Moreover, the Tesla Model S is NOT SOLAR-POWERED; it is battery powered. I have already stated that a useful battery-powered airplane could plausibly be developed in the future.
More generally, you are falsely accusing me of saying, "because this technology is bad today, therefore it always will be." But, what I actually said is, "there are basic scientific reasons why this technology is bad, and probably always will be." If you don't understand the difference between those two statements, then you have no understanding of how science and engineering work.
Although imagine the surface area and power requirements of something like this [shiply.com].
Many other people in this discussion have already suggested solar-powered airships, and I already replied to a couple of them agreeing that the idea has some potential. Nevertheless, airships are not airplanes, and will never compete in the same markets as a Cessna 188. (They could overlap a little with the Boeing 747, but not that much.)
The point I'm trying to make is that it's a stupid argument to say that the Solar Impulse 2 is not a drop-in replacement for any existing aircraft. It is a technology demonstrator.
And the point which I made rather clearly in my original post, was that the inadequacy of the Solar Impulse 2 is not due to technological immaturity, but rather due to fundamental physics that are unlikely to ever be overcome, no matter how much money and time is spent trying.
Of course it's not going to replace anything. It's going to advance the state of the art though, and it's going to bring about additional research and investment into related technologies in various applications.
No doubt. When did I ever suggest otherwise? That's not the subject of the article, though.
Laser far too easy to counter. Smoke and larger air particles can counter for ground troops.
A cloud of particulates will also (temporarily) blind the troops trying to hide inside it, reducing their situational awareness and ability to fight back. This could be beneficial to the attacker in the same way that machine guns are used to "suppress" enemy soldiers - forcing them to duck for cover has tactical utility even if you don't actually manage to hit any of them.
For missiles, drones, and airplanes simply roll or make the exterior 'wiggle'.
Just "wiggling" is probably not good enough; all the attacker has to do is target a part of the plane that remains in his line of sight throughout the whole of (or at least most of) the motion. The laser hits at the speed of light, so it's not like you're going to be able to jink fast enough to actually be untargetable.
A fast roll can help - if the defender could actually withstand the G-forces and (in the case of a manned plane) nausea. Even then, though, it's guaranteed to increase the required dwell time by about a factor of three. I expect that this method is only really useful for missiles; planes (manned or otherwise) are just too big to roll fast enough.
But a rail gun with say a varying 1-16 mj esp with smart ammo, is going to produce hits regardless of counter measures.
Perhaps. I don't think effective railguns will be miniaturized enough to stick on a fighter jet any time soon though. Maybe it would work on a large bomber or cargo plane, though?
To output 1MJ in a single second, I multiplied that by 3600 => 1 MW of power is needed.
By definition, a Watt is 1 Joule per second.
A 16.6 kW laser would need a minute, so if these guys don't mind flying in circles for a minute with their lasers on, they're probably good.
The question is, can you continuously illuminate the same small spot on a rapidly moving, distant target for a minute?
How are they doing regarding portable nuclear power stations that can fit into planes?
Actually, even a full 1 MW isn't an unreasonable amount of power to siphon off the main turbine(s) on a jet fighter: the shaft power on each engine is measured in 10s of MW. The additional mass of the required alternator, wiring, cooling, etc. would likely be substantial, though.
A one-second pulse that could slice 38x10x1mm in steel could probably do 10 to 100 times that in aluminum skin...
I was curious, so I took a stab at calculating how much easier aluminium is to melt than steel:
[room temperature] = [273 K]
[heat capacity by mass] = [molar heat capacity] / [atomic mass]
[heat of fusion by mass] = [molar heat of fusion] / [atomic mass]
[melting energy by mass] = ([melting point] - [room temperature]) * [heat capacity by mass] + [heat of fusion by mass]
[melting energy by volume] = [melting energy by mass] / [density]
For Fe (Iron):
[density] = [7.87 g/cm^3]
[atomic mass] = [55.8 g/mol]
[molar heat capacity] = [25.1 J/(mol*K)]
[melting point] = [1811 K]
[molar heat of fusion] = [13.8 kJ/mol]
[heat capacity by mass] = [25.1 J/(mol*K)] / [55.8 g/mol] = [0.450 J/(g*K)]
[heat of fusion by mass] = [13.8 kJ/mol] / [55.8 g/mol] = [247 J/g]
[melting energy by mass] = ([1811 K] - [273 K]) * [0.450 J/(g*K)] + [247 J/g] = [939 J/g]
[melting energy by volume] = [939 J/g] * [7.87 g/cm^3] = [7.39 kJ/cm^3]
For Al (Aluminium):
[density] = [2.70 g/cm^3]
[atomic mass] = [27.0 g/mol]
[molar heat capacity] = [24.2 J/(mol*K)]
[melting point] = [933 K]
[molar heat of fusion] = [10.7 kJ/mol]
[heat capacity by mass] = [24.2 J/(mol*K)] / [27.0 g/mol] = [0.896 J/(g*K)]
[heat of fusion by mass] = [10.7 kJ/mol] / [27.0 g/mol] = [396 J/g]
[melting energy by mass] = ([933 K] - [273 K]) * [0.896 J/(g*K)] + [396 J/g] = [987 J/g]
[melting energy by volume] = [987 J/g] * [2.70 g/cm^3] = [2.66 kJ/cm^3]
Assuming that only melting is required, it appears that Aluminium is only 3x easier to cut than steel. (If you really want to drill a deep hole in metal fast, it becomes necessary to actually boil it. But, I suspect that takes more power density than a 100 KW laser is likely to achieve against a fast-moving target at long distance.)
If you use solar power to produce the fuel, doesn't that mean that the 747 is entirely solar powered?
You can call that a solar-powered 747, if you're willing to let Tesla drivers who live near a fission power plant say that they drive an "atomic car".
More seriously, though: yes, of course, solar energy can be used indirectly to power airplanes - as can hydroelectric, wind, nuclear, etc. But, that's not really the topic we were discussing.
Do you understand why the Solar Impluse 2 looks like it does? I do.
Solar planes need a huge wingspan both to provide surface area on which to mount photovoltaic cells, and also in order to achieve the excellent lift-to-drag ratio required to fly with so little power available. Future improvements in solar cell efficiency, battery energy density, etc. could plausibly cut the wingspan in half (down to 737 size), but it would still be huge, slow, and fragile.
Unless you think solar cells can be built with greater than 100% efficiency, it's just not reasonable to expect much more than that, for reasons of basic physics which I already outlined in my original post.
Ah. Because any future solar-powered plane will necessarily look just like Solar Impulse 2. Got it.
Yes (if it's big enough to carry people, anyway).
Solar-powered airships have some potential. The square-cube law could be a problem though: airships generally need to be extremely large in order to be efficient, but you can't make it too big if you want to use solar power, because the mass of the ship grows faster than its surface area.
A battery-powered direct replacement is theoretically possible, but unlikely. The reason that hydrocarbons have such phenomenal energy density (for a chemical source, anyway), is that because of Earth's oxygen atmosphere, you don't have to carry 75+% of the required mass of reactants with you.
Batteries, on the other hand, force you to carry the oxidizer, which makes them quite heavy, even if the main chemical reaction is just as energetic as burning hydrocarbons. Fuel cells are the only battery-like option that I'm aware of that avoids this problem, but they still run on hydrocarbons. Metal-air batteries look good, until you realize that they actually get heavier as the flight progresses...
With major advances, battery power could work for short hops and/or low speeds, but it will probably never be viable for long-distance, high-speed manned flight.
Or if all else fails, just develop jet engines that run on biofuel and run the farming equipment on batteries.
Biofuel or synthetic fuel is a far more sensible power source for planes.
Synthetic fuels are a sensible idea. I would not call that a "solar-powered" plane though, for the same reason that I won't call a Tesla Model S a "methane-powered car", even if that's what your local grid power plant is burning.
Honestly... not really. Fuel is only about half the mass of a long-range hydrocarbon plane at take-off.
Not being able to dump spent batteries during the flight only increases the average mass of the plane over the course of the flight by about 30%, which isn't really that big of a deal compared to the more basic problem that current batteries weigh 40x as much as jet fuel for the same energy. The extra 30% is just a rounding error, in comparison.
The solar demonstrator plane in the article can only carry a single person, and yet, in order to fly, it requires the wingspan of a 747 (among the largest aircraft ever built). It's already far too wide to operate from most airports.
You want to take that plane - which can barely accommodate a single pilot - and weigh it down with multiple passengers, flight attendants, and amenities? You must be joking.
Remember, not everyone needs to get from Dallas to Tokyo in under 6 hours. The slower, cheaper, and more amenity rich trip on a properly considered PV powered flight are for people who want to get from A to B as part of a deadline relaxed vacation.
Those people who are not in a hurry will take trains or cruise ships, both of which actually exist today, and still work just fine even after being weighed down with attendants and amenities. Or - if you insist on air travel - perhaps an airship like vtcodger suggested above.
Namely, the 737 is designed with [...] big assed engines that produce lots of thrust on what is otherwise a ballistically propelled brick with aerofoil control surfaces.
1) Do you really not know the difference between the 737, and the 747 I was actually talking about in the post you replied to?
2) If you think either of those planes is "a ballistically propelled brick", you know nothing about aerodynamics.