Re:Another important exception: acid rain
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Global Dimming
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· Score: 1
I was not aware of the North American acid rain situation, but in the Scandinavian case I had the impression that attention had turned more to local causes, particularly forest fires
There hasn't been an increase in forest fires to match the increasing acidity. There HAS been an increase in burning of coal and lignite.
Re:Old-style environmentalism
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Global Dimming
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· Score: 1
The thing about the air, and for that matter the sea, is that as pollutants move, they disperse.
The thing about life and in particular the food chain, is that it concetrates pollutants. That's why it sometimes sucks to be at the top of the food chain; you get all the mercury and PCB's nice and concentrated.
One volcano can throw more assorted crud into the air (including SOx, NOx, the works) than the whole of the human race.
Unfortunately, humans can create chemicals that are not naturally found in Nature; CFC's, PCB's, SF6, organic mercury compounds etc, and can put others in places where they aren't usually found (lead and other reduced heavy metals). They can have disproportionately large effects on the environment - so it's not just about simple quantities.
Indeed, you are likely quite right. Unlike the case in Europe, American companies are unashemedly and actively trying to kill unions. That's not a good thing.
Depends on the situation, actually. I worked at a place where the computer systems had to work every night, and the "developers" did the operations. Then the sysadmin (a real ass) decided that only he would have access to the root password. Except he only worked days... Lot of fun when things went wrong with disks etc in the middle of the night. And he didn't provide a home number, so we couldn't even get even by calling him. I ended up having to root the box.
So the fact is that there is no one-size-fits-all answer; sometimes developers need to have complete access. The fact is that as appealing as hyper-compartimentalization is (for some personalities), as soon as you divide work (and people) into separate groups you have interfaces; and any good systems engineer will tell you that an interface is a source of problems...
Perhaps, but try telling the Corps they don't need a V/STOL aircraft... They seem pretty convinced they do. The argument is that they can operate from unprepared fields - they're thinking back to Guadalcanal.
Give the Harrier a break - it's a useful aircraft with a very challenging design requirement, that is almost 30 years old.
I've heard some unions in the US are pretty bad for that but I don't think it's true of all unions, and certainly not many in the UK.
Absolutely. Unions can definitely be a good thing, improving working conditions and pay. In fact, one could argue that without unions there would never have been a middle class; just a few ultra-rich capitalists, and zillions of working poor.
The problem with unions in the U.S. is mostly one of history - unions never really became a mass movement ("the American Dream": everyone thinks they are going to end up on top someday, and they want to be able to exploit everyone else when they do), employers never accepted unions, except in very limited situations when/where they were forced to, and unions only thrived in positions where they could effectively strangle businesses (garbage pickup, longshoremen, auto-manufacturing), creating a lot of inconvenience for everyone else in the process. Those unions concentrated on making a small number of their own rather wealthy, rather than expanding. The result is that unions are small and unpopular. Couple this with the particular history of organized crime and unions and they ended up with a serious image problem. To most people in the States "union" connotes a bunch of overpaid, underworked fat guys standing around on break, who you can't join unless you know uncle Tony. To most Swedes, "union" means those people who speak up for you if your workplace isn't safe.
In Sweden, they have been extracting oil for a decade from depths that should pre-date the appearance of plant life in the area...
Actually, no. The spent a lot of money, but the only oil they ever got up was lube oil from the drill rig. It was a big scam. Google "Siljan djupgas" and run it through babelfish.
Somewhat offtopic, I know, but I've been wondering: does anyone know if they have plans to make "The Hobbit"? They have most of the operation all set up, and they must be sitting on a mountain of cash... It'd be fun - I'd go see it.
a vacuum is still a great insulator. (that's why my coffee mug here has a vacuum between the inner and outer shells:)
No, in a vacuum things will cool radiatively. The innner walls of your thermos are reflective, which prevents thermal radiation from crossing the vacuum.
In space, things will cool off very quickly - if they are in shadow. In sunlight they will warm up. That's one of the many reasons it's hard to build spacecraft. As a satellite crosses into Earths shadow it's surface can drop by 150 deg C in a minute; it's hard to avoid breaking things in those kinds of temperature swings.
they don't, for instance, cut down the trees in their sacred land not for the trees themselves, but because cutting them down would cause their ancient spirits to become angry, who, in turn, will influence the Cloud Gods, who, again, with the Wind God and the Rain God, will cause havoc to their settlement
Bullshit. Maybe the Fire God likes that you cut down the trees and burn them in sacrifice so he influences the Earth Maiden to bring a fruitful harvest? How do you tell the difference?
Observation, hypothesis testing. The scientific method in short. Earlier cultures may use different language, but that's the basis for successfully dealing with your environment.
That being said, other people may have made valuable observations that you should pay attention to, even if they are couched in unfamiliar language.
"Linear thinking" is a meaningless catchphrase that people like to throw around as a criticism of modern thought, but it doesn't really mean anything. Modern thought is perfectly able to deal with feedback mechanisms.
heard of Zheng He? At his time, his ships were the largest in the world, at least five times bigger than the equivalent Portuguese ships.
Great example. His voyages were pretty impressive. But then the Chinese abandoned their fleets, and fifty years later were unable to build anything larger than a single-masted dhow. Which meant that when the Europeans showed up they were at a serious disadvantage, subject to economic exploitation and gunboat diplomacy. Abandoning the ir exploration was terribly shortsighted and frankly, a disastrous decision for the Chinese.
The lesson is not that the Chinese way of thinking is superior, it's that cultural arrogance can be disastrous. Yes, I understand that applies to us, too.
Which brings us to the real point here:- the Chinese, as with the Indians, didn't need to explore the world as much as the then Europeans did.
Whatever. They didn't, so they played second fiddle to the Europeans for a long, long time.
Two words:- Chamyogya Upanishad. Verse 211 or something.
Unfortunately, this one of those cultural artifacts that are beyond the reach of Google, so you probably won't know what I'm talking about, but let's put it this way:- it's one of the first references in world literature to the fact that the Earth is, as a matter of fact, revolving around the Sun, and not vice versa.
No, big difference. Some ancient verse claims the Earth revolves around the Sun. Another says the Earth is on the back of a turtle, standing on an Elephant etc. etc. Which is right? How do you tell the difference? With observation and the scientific method. If you had told me about an ancient Chinese text that discussed hypothesis testing I'd be impressed. But you haven't, so I'm not.
In modern society the average person can expect to live a longer, healthier life than in any other time or place. You can enjoy more travel, better food, a wider variety of entertainment, more access to information, access to a wider range of cultures and places, more of a political say in your future, etc. etc. If you are a woman you can for the first time in history choose how/if/when to bear children, meaning your life and worth isn't merely as a walking womb. That's pretty unique.
You spout off about our impending doom, but you should realize that modern society is the only society equipped to even begin to avoid this potential disaster. Other cultures have certainly caused (localized) environmental disasters (Australian aborigines destoying megafauna on their continent, Greeks deforesting their lands, the Easter Islanders, the extinction of the wooly mammoth). At least we see some of the consequences of our actions and are equipped to avoid them.
I'm not saying western civilization is perfect - by no means. But I am saying that by any objective measure western civilization - whether or not the fruit of the Latin alphabet - is pretty successful.
John Gray, author of Straw Dogs, one of the best books you could read this year, suggests that the Latin alphabet, with its complete abstraction from physical objects, has been the basis of western philosophical models, mainly to the detriment of our view of the world. He suggests that Chinese iconography, in contrast, helped the establishment of a worldview in which humans played less of a central role.
Why is that to the detriment of our worldview? Abstraction from physical objects has allowed us to develop things like abstract mathematics and music. Beside, the much-maligned western worldview has led to the most stunningly successful civilization anywhere, anywhen. Sure there are problems (environmental, societal, economic, political, spiritual) and things we could improve; but now we have the material security and scientific knowledge to begin dealing with those issues, and what is to say that any other civilization would be any better at dealing with these issues, anyway?. The adored Chinese worldview appears to have produced a stagnant behemoth unable to compete with modernity, nor provide the standard of living to the masses that we all take for granted. In addition, ancient China referred to itself as the 'middle kingdom', i.e. the center of the world (which is partly why it failed to keep up). That's pretty self-centered
in my book.
Finally, it is the development of modern science (in partciular astronomy) that has fundamentially changed our view of the Universe; we now know that we are but a small planet orbiting an average star in an average Galaxy etc etc. That's pretty humbling, and entirely the fruit of western thought.
People who confuse current problems with fundamental limitations, and who over-romanticise primitive cultures (while enjoying all the fruits of modern life) really, really irritate me.
Climate is no less chaotic than weather because it is nothing more than aggregate (usually seasonal) weather data collected over a period of years.
Again, climate is the set of variables that describe the statistical properties of the weather. Things like the mean and variance of temperature, rainfall, wind etc etc. It could also include the probability distribution of those variables. Even if you can't say exactly what the temperature in LA will be next month, you can give a probability distribution for it. What is so hard to understand about that? Have you never heard of statistical averaging (go look up "central limit theorem")?
Knowing where the temperature won't be is not the same as accurately predicting where it will be.
I disagree. Depending on how well you know where the temperature won't be, you can have a good idea of where it will be (if I know it won't be warmer than 21C and it won't be colder than 20C, what do you think I can predict about the temperature?). This is just semantics. 1000C was just pulled out of a hat; we can still use fairly simple physics to rule in a much tighter range than that. To illustrate the point: consider a pot of boiling water. You would have a very hard time predicting the exact flow patterns in the water (non-linear fluid dynamics that are hideously dependent on intial conditions). BUT you CAN predict with a high degree of precision both the time it will take to boil off all the water, and the frequency distribution of e.g. the bubbles.
reason being, as the model advances, the "realm of possibility" expands rapidly. This is where accuracy of the model and its initial starting condition becomes critical
I don't think you understand how the modeling is actually done. You run many, many models with a huge range of initial conditions, and you look at the distribution of outcomes. Climate models are not used in the same way as weather models; they are essentially used to "propagate" probabilities forward in time. The exact time-dependent path of the variables is less important, and you are not as sensistive to initial conditions.
If you had actually read the article you sent me
you'd have seen the phrase "attempts to treat climate prediction as an intial value problem will not be successful". That is what you seem to think climate models are, and I'm telling you that they are not. However, it does not necessarily mean that they are less accurate than weather models, as long as you understand what it is you are predicting (probability distributions of variables, not the variables themselves). That being said, as you go forward in time the width of the probability distribution can increase, but it doesn't do it in an exponential fashion, precisely because there are bounds that can be imposed from knowledge of the phyical processes involved, as well as statistical data from the past. The biggest uncertainty in climate models comes from uncertainties on the various phyical prescriptions used in the model (how clouds are treated etc). There modelers rely on using a wide range of presciptions, and factor in the associated range of outcomes in the resulting probability dsitribution.
Sure, you can predict the mean temperature, but it's no more astoundingly accurate a climate prediction to say "it'll likely be cold in the winter" than it is an amazingly accurate weather prediction to say "it'll likely be cold tonight after the sun goes down".
But that's not the prediction being made. The prediction is "if you double atmospheric CO2 levels the mean global temperature will rise between 2 and 8 degrees." I would argue that that has about as much certainty as the statement "it will get colder when the Sun goes down" (a fair bet but not necessarily guaranteed).
A non-linear system (climate) that's an aggregate of smaller non-linear systems (weather) cannot be more predictable than those smaller systems.It's a quaint notion of 19th-century Newtonian Determinism that the little errors cancel each other out when you move up to larger scales, but that's not how it works.
we still don't know why it's happening, second, we have no idea if it's normal, and third, we have no idea if it's a good thing or a bad thing.If you can point me to some good, reliable data that shows conclusively that it's overwhelmingly caused by human activity, and it's going to be a bad thing when it arrives, I'd love to see it.
Go read the National Academy of Sciences Report from their working group on climate change. Keep in mind that any politically sensitive report written by a committee of scientists is going to be very, very cautious in any conclusions. Scientists in general are loath to make any definitive statements, because it is in the nature of our training to always expect that we might be wrong (Certainty is for the religions). That being said, the mere fact that many scientists are saying in (for them) pretty strong terms that this is real and that this is a problem should make clear to you how serious this is. As for "overwhelming", well, what do you want - a personal note from God? Go educate yourself and keep an open mind. Learn the physics of radiative transfer and climate models. Understand the scientific method. Don't listen to either Green peace or Fox News but try to determine the truth for yourself. Read the primary litterature, but remember that science at that level is a debate, with people taking both sides. Things like the IPCC and the NAS report are the result of those debates, and it's pretty clear that the majority of scientists are coming down on the side of "global warming is real, mostly caused by us, and will be a problem".
I take it from your choice of words that you at least acknowledge that it is happening. That's a pretty big step that a lot of "skeptics" refuse to take. As for "why"; if there is one thing that we actually do understand very well, it is the effect of CO2 and other greenhouse gases on the transport of radiation (heat) in the atmosphere. There is incontrovertible data (google "keeling curve") evidence for increasing levels of CO2 in our atmosphere. You would have to concoct some pretty unlikely scenarios for why such an increase wouldn't result in an increase in temperatures. The fact that we do see the temperature increase coincident with the CO2 increase is a strong indication that they are linked.
Now, "normal". We do know that current levels of CO2 (and temperature) have not occurred at least in the past 400,000 years (scroll down). There was an interesting review in Science magazine about 3 years ago that showed even more data - but I'm afraid I can't find a WWW link. In any case, we do know that current CO2 levels are not "normal" to the current climate regime, and that the CO2 increase is entirely due to human sources.
Now for "bad"; we are talking major climate shifts at a rate that we have never before seen in climatological data (ice cores, tree rings, sediment layers), with the possible exception of certain mass-extinction periods (KT, PT etc), where the rates may have been as fast, though it is hard to tell. We're taking a rather delicate, metastable system and giving one helluva horse-kick. This is where there is uncertainty; it might merely be the end of places like Bangladesh, while Canadian farming does ok. Or you might see the Gulf stream shut down and the West Antarctic ice sheet melt. Those are sort of the end-ranges of probable outcomes under the current assumption of a doubling in CO2.
Note that if we keep burning coal into the 2100's we are talking about much more than a doubling of CO2. At that point most indications are for very bad things to happen (sea level rise on the order of 10-50 meters) etc. The models, like any work of science, admit uncertainties. But that normal "hedging" is misused by people with a political agenda to try and undermine the science. The fact is that basically all the models show warming; the question is just how much, and
None of these things have come remotely close to being tested yet. The closest any of them have come to being tested is running several different simulations on the same data and seeing how well they match.
We can and have compared models to historical records, with good matches (i.e. start the model with historical data up to AD1000, then run for the next 500 years and compare the model output with the actual historical record) . That's prehaps not a pure "prediction", but a model that accurately describes the past probably will do a decent job in the future. I suspect that you just don't want to hear that global warming is a real problem.
Actually, we are no better at predicting climate than weather. What looks like "greater accuracy" in predictions is simply the effect of scale. Weather and climate are, essentially, the same things on different scales.
No, that is not true. Weather is a dynamical phenomenon that is "chaotic" in the sense that the variables are exponentially dependent on initial conditions. Climate is the set of variables that describe the statistical behaviour of the weather. There is a big difference: we may not be able to predict the eaxct arrival time of a storm, but we CAN predict the mean temperature in LA over the next six months. Fundamentially, given good measures of the energy flow in and out of a climate system you can predict things like mean temperature, and with some understanding of the fluid dynamics and radiative transfer properties you can predict the variance in the temperature. But you cannot necessarily predict the exact time sequence of those variables (i.e. the weather). This is a critically important distinction, which a lot of people miss (or deliberately misrepresent for political reasons).
Let me put it a different way: climate is not totally unpredictable, because you know perfectly well that the mean global temperature isn't ever going to be 1000 deg C (until the Sun runs out of fuel, that is). Stated yet a different way, while the exact path in phase space in a chaotic system takes (the weather) is unpredictable, the volume in which the system can move (the climate) is finite, and hence predictable.
So, what does all this mean? It means that when scientists predict global warming, they can do it with much more certainty than with which they forecast the weather next week.
Uh, yeah. Ever heard of drag? You have to understand that this is not the same as an atmospheric re-entry, where you start with high velocity but very low air pressure. In re-entry, by the time you are low enough that the air is dense you are no longer travelling at 10 km/s. In the case of a railgun you leave the launcher at (more-or-less) sea level going 10 km/s.
Let's pull out our handy-dandy math skills and calculate what the deceleration is going to be:
From basic aerodynamics the drag deceleration a_d = Cd*rho_air*(v^2)/(l*rho_veh). Cd = drag coefficient, which for hypersonics is about 2. rho_air is air density (1 kg/m^3), l = length of vehicle (lets say 10 m), and rho_veh is the density of the vehicle (1000 kg/m^3). v is the vehicle velocity (note the square), say 10 km/s.
I get that the deceleration as you leave the launcher is about 2000 G's. For comparison, the Shuttle never sees more than maybe 2G's on (normal) reentry. The rate of energy deposited in the heat shield is approximately proportional to the deceleration, so we're talking about heating rates 1000 times larger than current re-entry technology - including ablative coatings - can handle.
A couple of interesting conclusions: smaller vehicles decelerate faster (inversely dependent on l), so you want to launch the largest vehicle you can - i.e. rather 50 tons than 1, all other things aside. Second, coming off the launcher is a pretty good approximation to hitting a wall, so you can't use this to launch people.
There are other issues to keep in mind - you cannot reach orbit with just a railgun. The vehicle has to fire rockets at apogee to avoid coming back to where it started (i.e. the ground).
So now you have to carry a rocket that can withstand the launch, which won't be easy to build, and reduces your payload. In short: railguns+atmosphere = really bad idea.
You may have been misled by various talk about superguns (Saddam had one) etc., but they did not have muzzle velocities anywhere close to what you'd need to reach orbit. They might reach orbital altitude, but not orbital velocity. Huge difference.
I think I torched that guy pretty well. Now on to your second comment.
You might be right. If you are, this is either the last or next to last generation of technological civilization, unless humanity gets real lucky with hydrogen fusion. What happens after that? Dieoff. [...] Actually, the most likely end to your scenario is that politicians will do nothing until no amount of expenditure of national resources can prevent disaster. Given your straw man arguments, I infer that this is the outcome you favor.
Yes, I do agree with you that oil will run out, most likely within 50-100 years. That will, frankly, suck. But we have coal, and while I don't favor it's use for many reasons, it could be used to sustain some kind of technological society for another 500 years.
But sooner or later we will no longer be able to sustain a population of 10-15 billion on this planet. Let us hope that we've mastered fusion and space travel by then, but understand that an equally likely alternative is dieoff followed by a sustained population of about 1 billion. I share your prediction about the lack of political action, but that is NOT the outcome I favor. I am merely more cynical than you are.
Here is my view: we face a very serious challenge to survival in the medium term. One that will require a lot of technologcal advances and clear thinking, not wishful thinking. Woolly-eyed fantasies about railguns (and to some extent beanstalks) bring us no closer to an actual solution to our problem. So in addition to dreaming (it's always ok to dream), start thinking critically and applying yourself in the areas where we have a real shot at progress.
Careful who you call idiot...
The fuel nuggets are encased in silicon carbide, but they are surrounded by softball-sized spheres of graphite. Silicon carbide is not a good moderator, so in order to get a reaction going you need graphite. The only way you could get away without a moderator would be to use higher enrichment in the fuel - but that brings with it other problems (proliferation, fast-neutron damage to the reactor, controllability).
Second, I get this feeling that you don't understand how depleted uranium weaponry even works. I keep reading all sorts of SF (read: stupid) posts about how it explodes inside the tank, or how some shell's explosion spreads uranium dust and debris all over, and whatnot.
Actually, it does spread dust all over. As the round goes through the armor it gets very hot and usually does deform and/or shatter. Bits of uranium come off. They promptly oxidize, creating lots of dust. Given that uranium is an alpha emitter it's pretty harmless unless ingested (say breathed in the form of dust). So you don't want to be near a tank that has been knocked out using DE rounds, but let's keep these risks in perspective - the tank is likely much more of a threat.
I have a question about these reactors: what happens when air gets into the reactor vessel? Don't you get a pretty big fire? It's notable that both Sellafield and Chernobyl were graphite-moderated reactors that ended up with graphite fires. Graphite is actually a difficult material to use in a reactor, it stores up energy in the lattice that can then be released at unpredicatble times. "Wigner energy". The link provides some interesting information, but take the nuclear-phobic tone with a grain of salt.
Another problem with pebble-beds is that they use natural or low-enriched uranium in a cycle where the fuel passes through the reactor relatively quickly and continuously (no big refueling outages). This makes them ideal Plutonium factories, which is obviously a matter of concern. Most of the graphite-moderated reactors ever built were designed primarily to produce Plutonium, including the Soviet RBMK's and the piles at Sellafield.
Don't get me wrong - I'm all for nuclear power for many reasons, but I'm not sure the pebble bed is that much of a breakthrough, and I don't think graphite is the best choice of material. And any operator of a plant in trouble that went home for the weekend should be shot. "Walk-away safe" my ass.
I don't buy an argument that because we haven't we cannot. I'm sure you see the fallacy there, too. We colonized Lousiana because it was cheaper, easier, faster -- more efficient and effective in our overall homogenization of the planet as a habitation for human beings. However, the absence of sea colonies does not preclude their impossibility.
The issue is that space is neither cheaper, nor easier, nor faster than just staying put. Which is why we're busy going nowhere. In the future there may be overpopulation, but there also may not. We have mastered the technology of birth control, and when enivironmental pressures get bad enough our population may stabilize or fall. There is no guarantee that we'll all of a sudden open up space colonization. At the very least we need several big technological breakthroughs before it could possibly happen (fusion, carbon nanotubes that actually work, high-Isp rockets, medical advances in stopping bone loss and radiation damage, and most of all, an economic reason to actually go there). I'm not saying it's impossible. I'm saying that none of those factors currently exist, so don't hold your breath.
If you really want to help make it happen, go work on one of the above. Or work on some other fundamental science; maybe the breakthrough will come from some unexpected direction.
Nobody is suggesting that materials be moved back to Earth via transportation with per pound costs remotely close to the Space Shuttle outside Luddite fantasy.
Getting material back to earth requires reducing that cost per pound by several orders of magnitude.
Obviously, yes. The problem is that there is as much of a difference between saying "we're gonna lower launch costs by two orders of magnitude" and actually doing it as there is between climbing a tall tree and reaching orbit. Look, space travel in fundamentally challenging because of physics; the amount of energy you have to control to get something going at 10 km/s is staggering. Highly energetic systems are inherently difficult to build and are dangerous. They way we've done it in the past is through the application of stupendous amounts of money; that amount of money just is no longer available. Your governments have other priorities and aren't willing to spend 3-5% of GDP in space, regardless of how promising a few visionaries think it is. Heartbreaking, yes, but also a fact.
The technologically literate consensus, which you and several moderators aren't part of, believes this possible.
Don't be childish. I'd be willing to bet you a jumbo of lunar cocaine that my resume shows as much or more technnical litteracy as yours. As for consensus, all I can say is that at the technical institue where I got my degrees they are busy closing down their aero department ("the future is in biotech"!). They even cancelled a class on space colonization for lack of student interest as well as - get this - a lack of technical rigour. A few enthusiasts think space can happen, but I know that there is no consensus that we have the technology now to do it.
However, explaining how in a way you can profit from will have to wait until somebody willing to dumb down the concepts to point-and-grunt level comes along, and I am not that person.
Oh, so you know how to do it, but I'm too stupid to understand? Great way to convince people to give you their money... I suggest you avoid space advocacy as a career choice.
Space Elevator (if CNT tech gets there) or raligun technology as improved for the Strategic Defense Initiative (almost ready) seem to be the best candidates.
We'll see about the space elevator. LIke I've said before, talk to me when they've built a suspension bridge with CNT; until then it has to be in the "cool lab tech still far from reality" category. As for railguns, puh-lease. There is a lot of difference between spending $G to launch a 10-g bullet at 8 km/s and launching a 50-ton vehicle into orbit. For starters how do you avoid melting the vehicle as it leaves the launcher low in the atmosphere?
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There hasn't been an increase in forest fires to match the increasing acidity. There HAS been an increase in burning of coal and lignite.
The thing about life and in particular the food chain, is that it concetrates pollutants. That's why it sometimes sucks to be at the top of the food chain; you get all the mercury and PCB's nice and concentrated.
One volcano can throw more assorted crud into the air (including SOx, NOx, the works) than the whole of the human race.
Unfortunately, humans can create chemicals that are not naturally found in Nature; CFC's, PCB's, SF6, organic mercury compounds etc, and can put others in places where they aren't usually found (lead and other reduced heavy metals). They can have disproportionately large effects on the environment - so it's not just about simple quantities.
Depends on the situation, actually. I worked at a place where the computer systems had to work every night, and the "developers" did the operations. Then the sysadmin (a real ass) decided that only he would have access to the root password. Except he only worked days... Lot of fun when things went wrong with disks etc in the middle of the night. And he didn't provide a home number, so we couldn't even get even by calling him. I ended up having to root the box.
So the fact is that there is no one-size-fits-all answer; sometimes developers need to have complete access. The fact is that as appealing as hyper-compartimentalization is (for some personalities), as soon as you divide work (and people) into separate groups you have interfaces; and any good systems engineer will tell you that an interface is a source of problems...
Give the Harrier a break - it's a useful aircraft with a very challenging design requirement, that is almost 30 years old.
But ask any British Falklands vet what he thinks of the Harrier and I bet you he'll love 'em. So they have their uses.
Absolutely. Unions can definitely be a good thing, improving working conditions and pay. In fact, one could argue that without unions there would never have been a middle class; just a few ultra-rich capitalists, and zillions of working poor.
The problem with unions in the U.S. is mostly one of history - unions never really became a mass movement ("the American Dream": everyone thinks they are going to end up on top someday, and they want to be able to exploit everyone else when they do), employers never accepted unions, except in very limited situations when/where they were forced to, and unions only thrived in positions where they could effectively strangle businesses (garbage pickup, longshoremen, auto-manufacturing), creating a lot of inconvenience for everyone else in the process. Those unions concentrated on making a small number of their own rather wealthy, rather than expanding. The result is that unions are small and unpopular. Couple this with the particular history of organized crime and unions and they ended up with a serious image problem. To most people in the States "union" connotes a bunch of overpaid, underworked fat guys standing around on break, who you can't join unless you know uncle Tony. To most Swedes, "union" means those people who speak up for you if your workplace isn't safe.
Actually, no. The spent a lot of money, but the only oil they ever got up was lube oil from the drill rig. It was a big scam. Google "Siljan djupgas" and run it through babelfish.
No, in a vacuum things will cool radiatively. The innner walls of your thermos are reflective, which prevents thermal radiation from crossing the vacuum. In space, things will cool off very quickly - if they are in shadow. In sunlight they will warm up. That's one of the many reasons it's hard to build spacecraft. As a satellite crosses into Earths shadow it's surface can drop by 150 deg C in a minute; it's hard to avoid breaking things in those kinds of temperature swings.
Bullshit. Maybe the Fire God likes that you cut down the trees and burn them in sacrifice so he influences the Earth Maiden to bring a fruitful harvest? How do you tell the difference? Observation, hypothesis testing. The scientific method in short. Earlier cultures may use different language, but that's the basis for successfully dealing with your environment. That being said, other people may have made valuable observations that you should pay attention to, even if they are couched in unfamiliar language.
"Linear thinking" is a meaningless catchphrase that people like to throw around as a criticism of modern thought, but it doesn't really mean anything. Modern thought is perfectly able to deal with feedback mechanisms.
heard of Zheng He? At his time, his ships were the largest in the world, at least five times bigger than the equivalent Portuguese ships.
Great example. His voyages were pretty impressive. But then the Chinese abandoned their fleets, and fifty years later were unable to build anything larger than a single-masted dhow. Which meant that when the Europeans showed up they were at a serious disadvantage, subject to economic exploitation and gunboat diplomacy. Abandoning the ir exploration was terribly shortsighted and frankly, a disastrous decision for the Chinese. The lesson is not that the Chinese way of thinking is superior, it's that cultural arrogance can be disastrous. Yes, I understand that applies to us, too.
Which brings us to the real point here:- the Chinese, as with the Indians, didn't need to explore the world as much as the then Europeans did.
Whatever. They didn't, so they played second fiddle to the Europeans for a long, long time.
Two words:- Chamyogya Upanishad. Verse 211 or something. Unfortunately, this one of those cultural artifacts that are beyond the reach of Google, so you probably won't know what I'm talking about, but let's put it this way:- it's one of the first references in world literature to the fact that the Earth is, as a matter of fact, revolving around the Sun, and not vice versa.
No, big difference. Some ancient verse claims the Earth revolves around the Sun. Another says the Earth is on the back of a turtle, standing on an Elephant etc. etc. Which is right? How do you tell the difference? With observation and the scientific method. If you had told me about an ancient Chinese text that discussed hypothesis testing I'd be impressed. But you haven't, so I'm not.
In modern society the average person can expect to live a longer, healthier life than in any other time or place. You can enjoy more travel, better food, a wider variety of entertainment, more access to information, access to a wider range of cultures and places, more of a political say in your future, etc. etc. If you are a woman you can for the first time in history choose how/if/when to bear children, meaning your life and worth isn't merely as a walking womb. That's pretty unique.
You spout off about our impending doom, but you should realize that modern society is the only society equipped to even begin to avoid this potential disaster. Other cultures have certainly caused (localized) environmental disasters (Australian aborigines destoying megafauna on their continent, Greeks deforesting their lands, the Easter Islanders, the extinction of the wooly mammoth). At least we see some of the consequences of our actions and are equipped to avoid them.
I'm not saying western civilization is perfect - by no means. But I am saying that by any objective measure western civilization - whether or not the fruit of the Latin alphabet - is pretty successful.
Why is that to the detriment of our worldview? Abstraction from physical objects has allowed us to develop things like abstract mathematics and music. Beside, the much-maligned western worldview has led to the most stunningly successful civilization anywhere, anywhen. Sure there are problems (environmental, societal, economic, political, spiritual) and things we could improve; but now we have the material security and scientific knowledge to begin dealing with those issues, and what is to say that any other civilization would be any better at dealing with these issues, anyway?. The adored Chinese worldview appears to have produced a stagnant behemoth unable to compete with modernity, nor provide the standard of living to the masses that we all take for granted. In addition, ancient China referred to itself as the 'middle kingdom', i.e. the center of the world (which is partly why it failed to keep up). That's pretty self-centered in my book.
Finally, it is the development of modern science (in partciular astronomy) that has fundamentially changed our view of the Universe; we now know that we are but a small planet orbiting an average star in an average Galaxy etc etc. That's pretty humbling, and entirely the fruit of western thought.
People who confuse current problems with fundamental limitations, and who over-romanticise primitive cultures (while enjoying all the fruits of modern life) really, really irritate me.
Again, climate is the set of variables that describe the statistical properties of the weather. Things like the mean and variance of temperature, rainfall, wind etc etc. It could also include the probability distribution of those variables. Even if you can't say exactly what the temperature in LA will be next month, you can give a probability distribution for it. What is so hard to understand about that? Have you never heard of statistical averaging (go look up "central limit theorem")?
Knowing where the temperature won't be is not the same as accurately predicting where it will be.
I disagree. Depending on how well you know where the temperature won't be, you can have a good idea of where it will be (if I know it won't be warmer than 21C and it won't be colder than 20C, what do you think I can predict about the temperature?). This is just semantics. 1000C was just pulled out of a hat; we can still use fairly simple physics to rule in a much tighter range than that. To illustrate the point: consider a pot of boiling water. You would have a very hard time predicting the exact flow patterns in the water (non-linear fluid dynamics that are hideously dependent on intial conditions). BUT you CAN predict with a high degree of precision both the time it will take to boil off all the water, and the frequency distribution of e.g. the bubbles.
reason being, as the model advances, the "realm of possibility" expands rapidly. This is where accuracy of the model and its initial starting condition becomes critical
I don't think you understand how the modeling is actually done. You run many, many models with a huge range of initial conditions, and you look at the distribution of outcomes. Climate models are not used in the same way as weather models; they are essentially used to "propagate" probabilities forward in time. The exact time-dependent path of the variables is less important, and you are not as sensistive to initial conditions.
If you had actually read the article you sent me you'd have seen the phrase "attempts to treat climate prediction as an intial value problem will not be successful". That is what you seem to think climate models are, and I'm telling you that they are not. However, it does not necessarily mean that they are less accurate than weather models, as long as you understand what it is you are predicting (probability distributions of variables, not the variables themselves). That being said, as you go forward in time the width of the probability distribution can increase, but it doesn't do it in an exponential fashion, precisely because there are bounds that can be imposed from knowledge of the phyical processes involved, as well as statistical data from the past. The biggest uncertainty in climate models comes from uncertainties on the various phyical prescriptions used in the model (how clouds are treated etc). There modelers rely on using a wide range of presciptions, and factor in the associated range of outcomes in the resulting probability dsitribution.
Sure, you can predict the mean temperature, but it's no more astoundingly accurate a climate prediction to say "it'll likely be cold in the winter" than it is an amazingly accurate weather prediction to say "it'll likely be cold tonight after the sun goes down".
But that's not the prediction being made. The prediction is "if you double atmospheric CO2 levels the mean global temperature will rise between 2 and 8 degrees." I would argue that that has about as much certainty as the statement "it will get colder when the Sun goes down" (a fair bet but not necessarily guaranteed).
A non-linear system (climate) that's an aggregate of smaller non-linear systems (weather) cannot be more predictable than those smaller systems.It's a quaint notion of 19th-century Newtonian Determinism that the little errors cancel each other out when you move up to larger scales, but that's not how it works.
Wrong. Go look up thermodynamics.
Go read the National Academy of Sciences Report from their working group on climate change. Keep in mind that any politically sensitive report written by a committee of scientists is going to be very, very cautious in any conclusions. Scientists in general are loath to make any definitive statements, because it is in the nature of our training to always expect that we might be wrong (Certainty is for the religions). That being said, the mere fact that many scientists are saying in (for them) pretty strong terms that this is real and that this is a problem should make clear to you how serious this is. As for "overwhelming", well, what do you want - a personal note from God? Go educate yourself and keep an open mind. Learn the physics of radiative transfer and climate models. Understand the scientific method. Don't listen to either Green peace or Fox News but try to determine the truth for yourself. Read the primary litterature, but remember that science at that level is a debate, with people taking both sides. Things like the IPCC and the NAS report are the result of those debates, and it's pretty clear that the majority of scientists are coming down on the side of "global warming is real, mostly caused by us, and will be a problem".
I take it from your choice of words that you at least acknowledge that it is happening. That's a pretty big step that a lot of "skeptics" refuse to take. As for "why"; if there is one thing that we actually do understand very well, it is the effect of CO2 and other greenhouse gases on the transport of radiation (heat) in the atmosphere. There is incontrovertible data (google "keeling curve") evidence for increasing levels of CO2 in our atmosphere. You would have to concoct some pretty unlikely scenarios for why such an increase wouldn't result in an increase in temperatures. The fact that we do see the temperature increase coincident with the CO2 increase is a strong indication that they are linked.
Now, "normal". We do know that current levels of CO2 (and temperature) have not occurred at least in the past 400,000 years (scroll down). There was an interesting review in Science magazine about 3 years ago that showed even more data - but I'm afraid I can't find a WWW link. In any case, we do know that current CO2 levels are not "normal" to the current climate regime, and that the CO2 increase is entirely due to human sources.
Now for "bad"; we are talking major climate shifts at a rate that we have never before seen in climatological data (ice cores, tree rings, sediment layers), with the possible exception of certain mass-extinction periods (KT, PT etc), where the rates may have been as fast, though it is hard to tell. We're taking a rather delicate, metastable system and giving one helluva horse-kick. This is where there is uncertainty; it might merely be the end of places like Bangladesh, while Canadian farming does ok. Or you might see the Gulf stream shut down and the West Antarctic ice sheet melt. Those are sort of the end-ranges of probable outcomes under the current assumption of a doubling in CO2. Note that if we keep burning coal into the 2100's we are talking about much more than a doubling of CO2. At that point most indications are for very bad things to happen (sea level rise on the order of 10-50 meters) etc. The models, like any work of science, admit uncertainties. But that normal "hedging" is misused by people with a political agenda to try and undermine the science. The fact is that basically all the models show warming; the question is just how much, and
We can and have compared models to historical records, with good matches (i.e. start the model with historical data up to AD1000, then run for the next 500 years and compare the model output with the actual historical record) . That's prehaps not a pure "prediction", but a model that accurately describes the past probably will do a decent job in the future. I suspect that you just don't want to hear that global warming is a real problem.
No, that is not true. Weather is a dynamical phenomenon that is "chaotic" in the sense that the variables are exponentially dependent on initial conditions. Climate is the set of variables that describe the statistical behaviour of the weather. There is a big difference: we may not be able to predict the eaxct arrival time of a storm, but we CAN predict the mean temperature in LA over the next six months. Fundamentially, given good measures of the energy flow in and out of a climate system you can predict things like mean temperature, and with some understanding of the fluid dynamics and radiative transfer properties you can predict the variance in the temperature. But you cannot necessarily predict the exact time sequence of those variables (i.e. the weather). This is a critically important distinction, which a lot of people miss (or deliberately misrepresent for political reasons).
Let me put it a different way: climate is not totally unpredictable, because you know perfectly well that the mean global temperature isn't ever going to be 1000 deg C (until the Sun runs out of fuel, that is). Stated yet a different way, while the exact path in phase space in a chaotic system takes (the weather) is unpredictable, the volume in which the system can move (the climate) is finite, and hence predictable.
So, what does all this mean? It means that when scientists predict global warming, they can do it with much more certainty than with which they forecast the weather next week.
Uh, yeah. Ever heard of drag? You have to understand that this is not the same as an atmospheric re-entry, where you start with high velocity but very low air pressure. In re-entry, by the time you are low enough that the air is dense you are no longer travelling at 10 km/s. In the case of a railgun you leave the launcher at (more-or-less) sea level going 10 km/s. Let's pull out our handy-dandy math skills and calculate what the deceleration is going to be: From basic aerodynamics the drag deceleration a_d = Cd*rho_air*(v^2)/(l*rho_veh). Cd = drag coefficient, which for hypersonics is about 2. rho_air is air density (1 kg/m^3), l = length of vehicle (lets say 10 m), and rho_veh is the density of the vehicle (1000 kg/m^3). v is the vehicle velocity (note the square), say 10 km/s. I get that the deceleration as you leave the launcher is about 2000 G's. For comparison, the Shuttle never sees more than maybe 2G's on (normal) reentry. The rate of energy deposited in the heat shield is approximately proportional to the deceleration, so we're talking about heating rates 1000 times larger than current re-entry technology - including ablative coatings - can handle.
A couple of interesting conclusions: smaller vehicles decelerate faster (inversely dependent on l), so you want to launch the largest vehicle you can - i.e. rather 50 tons than 1, all other things aside. Second, coming off the launcher is a pretty good approximation to hitting a wall, so you can't use this to launch people.
There are other issues to keep in mind - you cannot reach orbit with just a railgun. The vehicle has to fire rockets at apogee to avoid coming back to where it started (i.e. the ground). So now you have to carry a rocket that can withstand the launch, which won't be easy to build, and reduces your payload. In short: railguns+atmosphere = really bad idea.
You may have been misled by various talk about superguns (Saddam had one) etc., but they did not have muzzle velocities anywhere close to what you'd need to reach orbit. They might reach orbital altitude, but not orbital velocity. Huge difference.
I think I torched that guy pretty well. Now on to your second comment.
You might be right. If you are, this is either the last or next to last generation of technological civilization, unless humanity gets real lucky with hydrogen fusion. What happens after that? Dieoff. [...] Actually, the most likely end to your scenario is that politicians will do nothing until no amount of expenditure of national resources can prevent disaster. Given your straw man arguments, I infer that this is the outcome you favor.
Yes, I do agree with you that oil will run out, most likely within 50-100 years. That will, frankly, suck. But we have coal, and while I don't favor it's use for many reasons, it could be used to sustain some kind of technological society for another 500 years. But sooner or later we will no longer be able to sustain a population of 10-15 billion on this planet. Let us hope that we've mastered fusion and space travel by then, but understand that an equally likely alternative is dieoff followed by a sustained population of about 1 billion. I share your prediction about the lack of political action, but that is NOT the outcome I favor. I am merely more cynical than you are.
Here is my view: we face a very serious challenge to survival in the medium term. One that will require a lot of technologcal advances and clear thinking, not wishful thinking. Woolly-eyed fantasies about railguns (and to some extent beanstalks) bring us no closer to an actual solution to our problem. So in addition to dreaming (it's always ok to dream), start thinking critically and applying yourself in the areas where we have a real shot at progress.
Actually, it does spread dust all over. As the round goes through the armor it gets very hot and usually does deform and/or shatter. Bits of uranium come off. They promptly oxidize, creating lots of dust. Given that uranium is an alpha emitter it's pretty harmless unless ingested (say breathed in the form of dust). So you don't want to be near a tank that has been knocked out using DE rounds, but let's keep these risks in perspective - the tank is likely much more of a threat.
Another problem with pebble-beds is that they use natural or low-enriched uranium in a cycle where the fuel passes through the reactor relatively quickly and continuously (no big refueling outages). This makes them ideal Plutonium factories, which is obviously a matter of concern. Most of the graphite-moderated reactors ever built were designed primarily to produce Plutonium, including the Soviet RBMK's and the piles at Sellafield.
Don't get me wrong - I'm all for nuclear power for many reasons, but I'm not sure the pebble bed is that much of a breakthrough, and I don't think graphite is the best choice of material. And any operator of a plant in trouble that went home for the weekend should be shot. "Walk-away safe" my ass.
Oil?
The issue is that space is neither cheaper, nor easier, nor faster than just staying put. Which is why we're busy going nowhere. In the future there may be overpopulation, but there also may not. We have mastered the technology of birth control, and when enivironmental pressures get bad enough our population may stabilize or fall. There is no guarantee that we'll all of a sudden open up space colonization. At the very least we need several big technological breakthroughs before it could possibly happen (fusion, carbon nanotubes that actually work, high-Isp rockets, medical advances in stopping bone loss and radiation damage, and most of all, an economic reason to actually go there). I'm not saying it's impossible. I'm saying that none of those factors currently exist, so don't hold your breath.
If you really want to help make it happen, go work on one of the above. Or work on some other fundamental science; maybe the breakthrough will come from some unexpected direction.
Obviously, yes. The problem is that there is as much of a difference between saying "we're gonna lower launch costs by two orders of magnitude" and actually doing it as there is between climbing a tall tree and reaching orbit. Look, space travel in fundamentally challenging because of physics; the amount of energy you have to control to get something going at 10 km/s is staggering. Highly energetic systems are inherently difficult to build and are dangerous. They way we've done it in the past is through the application of stupendous amounts of money; that amount of money just is no longer available. Your governments have other priorities and aren't willing to spend 3-5% of GDP in space, regardless of how promising a few visionaries think it is. Heartbreaking, yes, but also a fact.
The technologically literate consensus, which you and several moderators aren't part of, believes this possible.
Don't be childish. I'd be willing to bet you a jumbo of lunar cocaine that my resume shows as much or more technnical litteracy as yours. As for consensus, all I can say is that at the technical institue where I got my degrees they are busy closing down their aero department ("the future is in biotech"!). They even cancelled a class on space colonization for lack of student interest as well as - get this - a lack of technical rigour. A few enthusiasts think space can happen, but I know that there is no consensus that we have the technology now to do it.
However, explaining how in a way you can profit from will have to wait until somebody willing to dumb down the concepts to point-and-grunt level comes along, and I am not that person.
Oh, so you know how to do it, but I'm too stupid to understand? Great way to convince people to give you their money... I suggest you avoid space advocacy as a career choice.
Space Elevator (if CNT tech gets there) or raligun technology as improved for the Strategic Defense Initiative (almost ready) seem to be the best candidates.
We'll see about the space elevator. LIke I've said before, talk to me when they've built a suspension bridge with CNT; until then it has to be in the "cool lab tech still far from reality" category. As for railguns, puh-lease. There is a lot of difference between spending $G to launch a 10-g bullet at 8 km/s and launching a 50-ton vehicle into orbit. For starters how do you avoid melting the vehicle as it leaves the launcher low in the atmosphere?