Seriously. Depending on how much physics you've already studied, the right place to start will vary. A passable (free) intro is in my free online physics textbook http://www.phy.duke.edu/~rgb/C..., or wikipedia articles. A good intermediate treatment might be Griffiths' Classical Electrodynamics. If you want the pure quill uncut stuff, J. D. Jackson's Classical Electrodynamics is excellent, but it is not for the faint of heart or the wussy of PDE-fu.
In a nutshell, parallel currents of electric charge attract; antiparallel charged currents repel, changing charged currents radiate electromagnetic energy, and there are electrostatic forces happening in there somewhere too, in the cases where the currents are produced by unbalanced moving charge. Oh, and there is a fair bit of twistiness to the magnetic fields (called "curl") and forces, and the currents in question in "magnets" (or the general magnetic susceptibility of materials) tend to be non-dissipative (quantum) nuclear, atomic, or molecular circulations of charge, not Ohm's law type currents in a resistor. Ferromagnets in particular are what is being referred to, and they are characterized by long range order and a "permanent" magnetization in the absence of an external field below a certain temperature.
Oops, my bad, sorry. For some reason I added a mental decade to the year. I should have checked, as my memory ain't what it used to be, and it never was much:-)
is, as one can see, order of a foot in diameter and could produce electrons at order of 6 MeV in 1940. Yes, that is actually before the US entered WWII and long before the invention of the cyclotron. That is gamma ~12, or v ~ 0.997 c. So if the top presentation were at all relevant to TFA it would actually be boring. One might safely conclude that it is wrong and boring.
The betatron was damn near the first particle accelerator truly worthy of the name, and was just about exactly 12" in diameter (a bit larger than that including the frame for the magnets etc) as one can clearly see in the second photo on this page if not the first.
Yeah, I've done a fair bit of time as sysadmin of several networks AND enjoy the cool stuff that comes with change and improvement in hardware and software over time.
Systemd no doubt will have growing pains associated with it, but I still remember the "growing pains" associated with kernel 2.0 (the first multiprocessor kernel) and issues with resource locking and ever so much more. Anybody want to assert that this wasn't worth it, that "single core/single processor systems were good enough for my granddad, so they are good enough for me"? Server environment or not?
Decisions like this are always about cost/benefit, risk, long term ROI. And the risks are highly exaggerated. I'm pretty certain that one will be able to squeeze system down to a slowly varying or unvarying configuration that is very conservative and stable as a rock, even with systemd. I -- mostly -- managed it with kernels that "could" decide to deadlock on some resource, and when the few mission critical exceptions to this appeared, they were aggressively resolved on the kernel lists and rapidly appeared in the community. The main thing is the locking down of the server configurations to avoid the higher risk stuff, and aggressive pursuit of problems that arise anyway, which is really no different than with init, or with Microsoft, or with Apple, or with BSD, or...
But look at the far-side benefits! Never having to give up a favorite app as long as some stable version of it once existed? That is awesome. Dynamical provisioning, possibly even across completely different operating systems? The death of the virtual machine as a standalone, resource-wasteful appliance? Sure, there may well be a world of pain between here and there, although I doubt it -- humans will almost certainly keep the pain within "tolerable" thresholds as the idea is developed, just as they did with all of the other major advances in all of the other major releases of all of the major operating systems. Change is pain, but changes that "wreck everything" are actually rare. That's what alpha/beta/early implementation are for, and we know how to use them to confine this level of pain to a select group of hacker masochists who thrive on it.
On that day, maybe just maybe, systemd will save their ass, keep them from having to replace some treasured piece of software and still be able to run on the latest hardware with up to date kernels and so on.
I've been doing Unix (with init) for a very long time at this point. I have multiple books on the Unix architecture and how to use systems commands to write fully complex software, and have written a fair pile of software using this interface. It had the advantage of simplicity and scalability. It had the disadvantage of simplicity and scalability, as the systems it runs on grew ever more complex.
Everybody is worried about "too much complexity", but Unix in general and linux in particular long, long ago passed the threshold of "insanely complex". Linux (collectively) is arguably one of the most complex things ever build by the human species. The real question is whether the integrated intelligence of the linux community is up to the task of taming the idea of systemd to where it is a benefit, not a cost, to where it enables (eventually) the transparent execution of any binary from any system on a systemd-based system, with fully automated provisioning of the libraries as needed in real time as long as they are not encumbered legally and are available securely from the net.
We deal with that now, of course, and it is so bloody complex and limiting that it totally sucks. People are constantly forced to choose between upgrading the OS/release/whatever and losing a favorite app or (shudder) figuring out how to rebuild it, in place, on the new release -- if that is even possible.
I'll suffer a bit -- differently, of course -- now in the mere hope that in five years I can run "anything" on whatever system I happen to be using and have it -- just work.
a) It's already done, and is called "wikipedia". The problem of accessing wikipedia after the solar flare in a few days wipes out human technological civilization is left as an exercise for the reader.
b) OK, so it's not really done, and is going to be even less done as paper books more or less disappear from the world and people stop learning how to read because their personal digital implant delivers content directly into your cortex in full sensory mode, all of which goes away when a nuclear war followed by a space alien invasion reduces humans to a marginal species living in abandoned mines and sewage tunnels and living on rats. Brevity is then the soul of wit. We need three things:
1) How to make and blow glass. 2) How to turn glass into lenses and lenses into microscopes and telescopes.
These two things are already sufficient. They extend human senses into the microscopic and macroscopic, otherwise hidden, Universe, and nothing but common sense and observation is required from that point on. However,
3) How to build a printing press.
is also good, provided that people can still read.
Oh, you want to rebuild civilization QUICKLY? Either we're restarting from a partial, not full, reboot (that is, we still have easy access to things like unburned oil and coal, iron, maybe a few undamaged nuclear power plants with the engineers to run them) or it's just not happening!
The problem, you see, is easy access to those resources. The more we deplete the Earth's crust of readily minable resources, the harder it is to reboot civilization on a collapse. We just don't have a lot of places where oil still comes oozing up to the surface of the Earth, for example, so why and how exactly are people going to go looking for it a kilometer or two down? How easy is it going to be to find any? Steel requires iron (still fairly plentiful, granted) and coal. Hmmm, easy coal isn't so easy any more. Easy copper, not so much. Easy aluminum? No such thing, needs massive amounts of electricity (although ore is still plentiful enough. Even making chemical reagents like sulphuric or nitric or hydrochloric acid (key to building nearly anything interesting) require sulphur, salt, electricity.
This is what is going to be tough. Bootstrapping directly from type 0 pre-civilization to type 2 civilization is going to be very difficult if we've depleted all of the easy pathways to 2 while we are type 1, even if we preserve usable copies of wikipedia, the CRC handbook, the library of congress science section, the entire proceedings of the IEEE, and a complete copy of all patents ever filed in the US patent office (and have people who can read them, and who have managed to learn calculus and build stuff). Hydroelectric power, maybe. Alcohol can drive simple motors. But going straight to nuclear or photovoltaics is going to be pretty much impossible, and going the coal/oil route we've followed the first time is going to be much, much harder.
The best thing, therefore, is to take care of the civilization we've got...
I not only have seen spectrographs of the atmospheric radiative effect, I actually own a copy of Grant Petty's book A First Course in Atmospheric Radiation", and have taught both undergrad and grad electrodynamics for over 30 years. Precisely what does this have to do with my statements above? I'm not "denying" that the greenhouse effect exists -- there is direct spectroscopic evidence for it. I can derive one simple model (a complete absorber model leading to 1.19x warming) for it on a piece of paper in three minutes. I regularly argue with people who want to claim that it doesn't exist at all, or that it violates the second law. Both are absurd -- of course it exists, and no it doesn't violate the laws of thermodynamics it is a direct consequence of them (although the actual atmospheric radiation effect is a great deal more complex than simple single layer models!)
All of this is completely irrelevant to my statements above. Let me explain the null hypothesis, since the terminology apparently eludes you. It is this: Supposed we increase atmospheric CO_2 from 300 to 600 ppm in the very simplest model planet we can imagine -- one where the only change we permit is this. One can work through the arguments for the greenhouse warming one should expect -- they involve looking at the measured spectrum of CO_2, doing a bit of work with the relevant Beers-Lambert formula, and thinking a bit about the lapse rate -- but in the end most people who do the calculation end up with somewhere between a 1 C and 1.5 C warming.
At this point one invokes the principle of ignorance -- we don't really know how the entire Earth system will respond nonlinearly to this. Nor do we have any plausible means with which to measure it -- we have no experimental Earths to do controlled observations with similar structure, e.g. 70% saltwater ocean confined in a complex pattern of continents -- and we already know that the establishment of particular circulation patterns of the confined ocean and atmosphere were the sole really plausible explanation for the Pliestocene ice age, which started when the isthmus of Panama closed between 3 and 4 million years ago.
We also know one important point from linear stability analysis. For the Earth's climate system to be stable at all, it has to respond to perturbations in forcing by opposing the change, not augmenting it. That is, at a stable point, the response to all perturbations has to be to push the system back to the stable point, not away from it, or the point isn't stable, it is unstable, like balancing a pencil on its point. This principle is taught in introductory first year physics, so presumably you are familiar with it.
The Earth's top of atmosphere "forcing" varies by roughly 90 W/m^2 every year, simply from the eccentricity of the Earth's orbit. It varies by order of a percent from fluctuations in albedo (mostly due to clouds, but also due to shrinking and expanding ice and snow fields) on a much shorter time scale, as short as days. The climate is if anything remarkably stable, at least on a short time scale (and we have the devil's own time explaining any of the longer time scale variations observed in the paleo record or the much shorter thermometric record, where the stable point itself exhibits considerable climate "drift" even while remaining sufficiently locally stable to be still considered "climate"). There is little evidence of any sort of runaway nonlinear instability from this natural variation in forcing. Quite the opposite, in fact, right up to the point where factors we do not yet really understand and cannot compute or predict seem to cause transitions like the advent of glaciation in the current, continuing, Pleistocene ice age.
Given a lack of knowledge of how the enormously complex system will respond to a small, linear variation in forcing on top of the annual periodic variation in forcing that is roughly two orders of magnitude larger and incid
Yes, you have. You missed, for example, the entire bit about the null hypothesis. You also missed the fact that I am not asserting that the Earth isn't warming, or that CO_2 increases are probably not a factor in the warming we have experienced. I can actually read a spectrograph and have a decent understanding of the GHE from the basic physics on up. I'm only pointing out that the trivial model you suggest is precisely why we should doubt that TCS is over 2 C! That is, the null hypothesis is around 1 to 1.5 C total warming from CO_2 alone, which is all we have even weak direct evidence for. Everything else is built on a shaky tower of model assumptions, physics toy models, and an attempt to solve a probably unsolvably difficult problem in a particular way to put some sort of stamp of authenticity on a conclusion that is both unfounded and so far, contradicted pretty strongly by observational fact.
One knows this because one studies nonlinear chaotic systems (in systems with far simpler coupled DEs), learns about things like the Kolmogorov scale, turbulence, Lyupanov exponents, one monkeys about with solving nonlinear coupled ODEs with both adequate and inadequate integration stepsize. From this one learns that the climate models are arguably some 30 orders of magnitude shy of a spatiotemporal step that one might reasonably expect to be able to integrate over some significant time to get an actual solution.
This gap is bridged two ways. One of the two ways is to make pure assertions about the physics in between the Kolmogorov scale and the scale we can afford to integrate. For example, forget local dynamics of thunderstorms -- thunderstorms are phenomena that are basically invisible on a 100x100x1 km grid. Assume that one can use some sort of probability distribution of thunder-storminess in the dynamics and that this is adequate to describe all of the violent and rapid heat transport vertically and laterally in thunderstorms with sizes distributed on length scales of 2 to 10 km and with time scales of significant variation of a minute or longer (the time required to get out of your car and reach the house, of course). Do this repeatedly, with everything -- tornadoes (and other small scale velocity fields with nonzero curl) -- gone, replaced with and assertion regarding averages. Don't worry about the fact that none of these assertions can be formally derived and that we know perfectly well that we won't get the right answer for any other chaotic system studied by mankind (for example, try this for a simple damped driven rigid oscillator, replace the driving force with an average of almost any sort and see what happens) thus far if we do this, but don't forget to shout that the models are based on physics if anybody dares to point this out.
The other is even better. When the models are run, they are still nonlinear iterated maps, even if they are integrated with approximated dynamics and an enormous spatiotemporal step, so they still exhibit chaos and make lots of nifty patterns that "look like" weather (and even are a theoreticaly and empirically defensible approximation to weather, for integration periods of a week or so from reasonable well-known initial conditions before the chaotic trajectories diverge to fill phase space and render them worthless for weather prediction any more). One gets, from even tiny perturbations of the initial conditions and/or physical parameters, butterfly-effect divergences that create an entire bundle of "possible microtrajectories" for the model system being solved which is, note well, not even arguably the actual equation of motion for the coupled Earth-Sun-Atmosphere-Ocean system, it is a pure toy model that nobody sane would expect to actually work. And of course it empirically does not work, not even close. The microtrajectories produced, which generally only work across a reference period (trial data) by carefully choosing large, cancelling forcing terms in the approximated dynamics, end up having far too much variance (compare to the actual climate), the wrong autocorrelation spectrum (direct evidence of the wrong physics but who is counting), and range from (for CMIP5 models) a handful that actually cool over very long time scales to some that go sky high.
The actual Earth, of course, only has one trajectory and it doesn't look anything like any of these model trajectories. So now comes the best part. The "ensemble" of microtrajectories is actually averaged and used as a prediction for the trajectory.
Words fail me. Again to fall back on a trivial example, imagine taking a damped driven rigid rod oscillator operating in the chaotic regime, starting it from an "ensemble" of slightly perturbed different initial conditions, integrating it on so coarse a timestep that one gets chaos but perhaps chaos that is not even qualitatively similar to the chaos observed with an adequate timestep, and then
Was that to me? Sorry, I have physics classes to teach and am insanely busy teaching them, and there is no point in posting a short answer to a difficult or subtle question. I had time to answer this morning and did so. Not that I expect my reply to make any difference in your beliefs. If you wish to accept the word of the climate "oracles" as god-descended truth instead of something that, well, could easily be doubted on multiple grounds I doubt that pointing those grounds out will change your beliefs. I'll merely point out that actual statisticians often make fun of climate scientists (see e.g. William Briggs' blog and his patient, detailed posts on the subject), and for pretty good reasons. Making reliable inferences from computational models in this class is something I've done a fair bit of work in, and it is very, very difficult. This isn't computing the trajectory of a baseball.
I was replying to "Here is a graph...". It states that it LOOKS like SLR is already happening (duh!) and that the rise is accelerating.
As to whether or not the future projections are based on physics: How, exactly? Do you mean that there is physics in the models used to make those projections? No argument. Are the models capable of using the physics that are in them to make a prediction of future SLR that can be falsified? Not in any possible way. Hence one integrates the models (contingent on the assumptions that go into the "physics" inside, which is often in the form of semi-empirical formulae that kind-of-work for short-run weather forecasting in the models from whence the GCMs are descended until chaos makes these predictions worthless) , observes a staggering range of possible future climates, assumes further that in this case -- more or less uniquely in the general class of problems "like" this in mathematics and physics -- it's OK to solve the problem on a spatiotemporal granularity close to 10^30th larger than the Kolmogorov scale, assumes further that even though the resulting bundle of trajectories is so broad as to be nearly useless and each one is a "possible" future history of the climate, that the mean of this bundle is a number that is somehow relevant to the future behavior of the actual climate as a single realization of a space of possibilities that is almost certainly far larger than the model space given the coarse graining and smoothing, goes one step beyond that and average over many models that aren't even independent and what -- pray to a benign deity that these are good numbers on which to bet trillions of dollars and millions of lives on right now to -- perhaps -- avoid a catastrophe later?
Excuse me? Seriously? The SLR since roughly 1870 is clearly published in a number of places and amounts to roughly 9 inches. Quite aside from the infinity of statistical fallacies one can generate by fitting linear trends to timeseries data: http://wmbriggs.com/blog/?p=51..., or if you prefer a longer and much more detailed statistical (Bayesian) explication of the problems: http://wmbriggs.com/blog/?p=51..., and the fact that those problems are multiplied enormously when you seek to fit a nonlinear trend to the data, to argue that this timeseries reveals "acceleration", presumably correlated with increased CO_2 near the end, in spite of the fact that its greatest visible period of "acceleration" is in the early 20th century when CO_2 levels were nearly irrelevant to any observed climate change in everybody's models is not terribly sensible.
Then we could analyze the other fallacies in this sort of graph used as an argument for 5 meter SLR by 2100. For example, the current rate of SLR is around maybe 3 cm/decade -- a bit over an inch a decade. In the 8.5 decades left in the century, we might be looking at anywhere from 8 inches to a foot of SLR based on the data as we have it now, foolishly extrapolating a linear trend indefinitely into the future for a highly nonlinear chaotic system that is perfectly capable of things like glacial transitions (either way) or century-scale droughts without any help at all from humans. However, this still doesn't do the problem justice, because of the differential probable error bars visible even in the figure you present, and the fact that the measurement methodology changes near the end, and the fact that to properly account for SLR either way one really has to take gravity and surface deformation into account in multiple ways. In particular, the crust is continuing the process of isostatic rebound resulting from the melting of an ice layer several kilometers thick on the polar regions "only" 12,000 or so years ago. The continents continue to drift. The sea bottom continues to remodel as this occurs. Much of this produces changes that we are only barely able to measure, in some places some of the time, now (mostly with satellites and e.g. GRACE, but there is a bit of chicken and egg problem there as well). There is the fact that an isostatic ocean produces LOCALIZED SLR where warm water floats on cooler water and can produce this sort of SLR in mid-ocean far from any tidal gauges. Tidal gauges in coastal areas are largely locked to local surface temperatures of the water. The satellite record includes this -- the tide gauge record does not, and since 70% of the Earth's surface is ocean, and nearly all of this ocean is "far" from continental boundaries and the comparatively tiny number of measurement stations that go back into the distant past with isostatic changes that are impossible to measure retroactively or correct for in the present, the probable error in global SLR visible in these curves is IMO at least almost certainly significantly underestimated, and that is before one gets to the factor of roughly 10 that Briggs asserts one is likely to underestimate true error by when fitting a linear trend to a timeseries.
So what the data might justify is this. The "rate" (linear trend) of SLR over the last 145 years is something like 2 plus or minus 2 mm/year -- it could be anywhere from basically 0 to as much as 4 mm/year, and this might well still underestimate the probable error. The "current rate" (measured with much better precision, but beware picking endpoints!) is perhaps order of 3 mm/year, plus or minus what, a mm/year? At least? Well within the long term average, and clearly visible as being (probably) equaled or exceeded in the past in periods with little possible correlation/causality linkage with CO_2, even in so short a record.
There isn't any conceivable argument that can be made on the basis of either s
What I still haven't seen in is just 1 climate model that explains most of the observed current and historical data.
You could have ended this sentence right there and it would be accurate. So of course any additional clause that you append isn't going to change that. However, it does make the argument contained in that clause less compelling.
Expect more AC posts like this, the power companies are paying green washers to come up with moronic arguments so people in the same tribe can re-post them thinking they actually make sense and won't look like a tool in the process:
Really. "The power companies" are paying people to blog against solar? So a company like, say, Duke Power posts a job opening somewhere and interviews candidates:
"So, we are interested in hiring somebody with excellent blogging skills."
"Oh, sure, if you observe my pale and pasty skin, my slightly overweight condition, and the callouses on my finger tips you can see that I have a long history of sitting and keyboarding instead of working. Indeed, my resume shows the same thing! Look at that -- I haven't got a single thing on there that Duke Power could possible be interested in. In fact, all I want to do is return home so I can visit my "tribe" online."
"Uh, so, why exactly are you applying for this job?"
"My mother is making me look for work! She claims that I'm stinking up the basement because I don't have time to shower or do her silly laundry while I'm busy online! Can you believe it?"
"You sound just perfect for our position. Now, let me ask you -- do you have a social conscience? I mean, is there anything you believe in very strongly -- world peace, God, the environment, racism, sexism? Oh, and I have to ask -- do you collect or distribute pictures of underage nude members of the animal kingdom more complex than arthropods on any of your computers?"
(Dazed silence.) "Uhhh, no? And, like I dunno, do anime cartoons of big-eyed sort-of-japanese nymphet ninja chicks count? They're AI, so they're probably less complex than an arthropod? Can I go now? I applied, so my mom will be happy."
"No, wait, you're hired! And before you panic, you get to work from home! Indeed, your job is going to be really simple: go online and trash-talk solar energy to your homies. But only rooftop solar. We are investing pretty heavily in solar ourselves and want to be seen by the public as being progressive (hey, we even bought out an entire power company called Progressive), but even though we are still paying people to let us load level their air conditioners in peak times, even though it is an enormous, expensive hassle to add generating capacity, even though our inclination to add more quick-online capacity would involve natural gas and hence fracking (speaking of which, how do you feel about throwing in the occasional word of praise for fracking, how it is making the world a better place and stabilizing the continental land mass so that it will eventually prevent the Big One, the next New Madrid earthquake as it were) we are terribly worried that rooftop solar will put us out of business in the next thirty years or so. We want to win the hearts and minds of America, and your online homeboys, well, they are America."
"Dude, if you call my friends `homies' one more time, I'm gonna leave and my mom can suck an oyster. Let me get this straight. All I have to do is dis rooftop solar while I'm playing my online games and visiting lame blogs and you pay me money? And I can do it from home?"
"That's it. You'll be a full-time work-at-home employee of Duke Power. Benefits and everything. You'll need to keep a log of the websites you visit to bash PV rooftop installations, and you'll have to undergo a brief training program where you learn of just how awful, dangerous, and expensive it is and how much better it is for consumers to let us install solar PV farms and continue to deliver energy safely to their wall sockets. Hey, you can even afford to move out of your mom's basement!"
"Well, OK. But nix on the moving thing -- my mom's a super cook and my Sailor Moon poster is kinda glued to the wall at this point, if you know what I mean. Thanks, Duke Power! You just hired yourself a troll! You just wait! When I get through with solar, none of my friends will even think of working out the amortizati
... because of the way MongoDB actually stores records and parses them. It is more or less a simple tree or linked list, and hence doing almost anything involves decending branches to the leaves. This is horrendously inefficient in many contexts, while still being perfectly lovely in others. Just doing a match, though, can involve a non-polynomial time search. Maybe they've improved this from when I was trying to use Mongo to drive modelling, but I doubt it as it would have involved substantially changing the way the data is actually stored and dereferenced. I had to cheat substantially in order to get anything like decent performance, and any of the SQLs outperformed it handily.
Note well that it was strictly a scaling issue. For small trees and DBs, it probably works well enough. For large DBs with millions of records and substantial structure, it is like molasses. Only worse.
I had a friend who had a Benjamin, actually, but this was back in the 60's, and yes, I was jealous as I had only a.177 break-action pellet rifle. Speciality pellet that had, as you note, a muzzle velocity "comparable" to a 22 short. Yes (Google being Our Friend), 22 LR is 1200 fps (for a reason!), a 22 short is around 1000 fps, and a Benjamin is (usually, dependent on model and mechanism) 900, which is quite respectable but depends on pellet weight.
When I decided as an Old Guy to get a really good hunting class pellet rifle I looked hard at the Benjamin-Sheridans but ended up picking the Walther Falcon Hunter edition, which is also 900 fps and fires a variety of standard or "hunting class".22 pellets. I actually haven't tried to fire it through a 4x4 -- but who knows? I got it for my sons (really, my youngest son who is the most avid hunter) and it drops a rabbit as readily as a 22. I'm guessing that a hollow point pellet would quite possibly kill a deer shot at reasonably close range (10 yards or so and a heart or perfect head shot) -- as a 22 might -- or for that matter a human. I doubt it would "drop" either one, though and this is something I would never try with either rifle, of course, unless it is after the apocalypse and it is kill a deer with the pellet rifle or go hungry:-). In the old days I saw for myself that a daisy BB gun would leave a very painful divot in human skin without quite penetrating (no, I did not pull that particular trigger). You would not try that with the Walther as it would go clean through your leg if it didn't hit the bone, and would have a pretty good chance of chipping or breaking the bone.
The Walther, in other words, like the Benjamin Marauder etc, is definitely not a toy gun. I also have an older.177 caliber pellet gun that fires a pellet slowly enough that you can "see" it (barely) en route and one doesn't fire it at a plywood sheet as it might bounce back (or more likely, embed itself 3 mm into the wood). No comparison.
Bear in mind that it isn't just muzzle velocity, it is mass. A.22 LR is typically a 40 grain bullet, a.22 short is around 30 grain, compared to a "standard".22 pellet at 14.3 grains and speciality hunting pellets at 20 to as much as 40 grains). The.22 LR has around 5x the kinetic energy of almost any pellet rifle out of the bore and that's a simple fact. Finally, it is ballistic drag. Pellets generally aren't fired fast enough to get sufficient stability from rifling and spin to be particularly accurate, which accounts for their "diabolo" waist. This also produces substantial drag -- it is being stabilized by drag. This means that pellet rifles have a rapid dropoff of their muzzle velocity and are really only suitable for short range hunting for any sort of larger game. Real.22 rifles get enough spin that they can avoid the skirted diabolo design, avoid much of the drag, and still have equal or better precision and ballistics. The third issue is the sound barrier. That's the thing that limits.22 muzzle velocity even in the case of the rifle -- there is substantial turbulence as a bullet passes through the sound barrier slowing down, and one needs streamlined bullet shapes like those found in centerfire rifles (which do indeed fire even.22-ish caliber highly streamlined and much more massive bullets with muzzle velocities well over the speed of sound) to have decent ballistics. Rimfire.22 LR bullets are not streamlined and are designed to shoot just under the speed of sound (or in the case of 1200 fps almost instantly drop down under it as the bullet "settles" out of the barrel) so that they usually have decent but not impressive precision (bench grouping). Competition grade guns (rimfire or pellet) usually shoot bullets at muzzle velocities deliberately well under the speed of sound --.22 shorts, not
...Or, \pi R^2 = 3 x 400 \approx 1200 square meters of collector area (concentrated down by the mirrors). If so, the collector surface receives around 1.2 MW peak, or at 80% efficiency 960 KW converted. The 12 KW is therefore not conceivably peak, it has to be a 24 hour average -- 12*24 = 288 KW-hr, which assumes peak can be (nearly) maintained for close to 8 hours a day. This completely changes the numbers. 288 KW-hr/day is $43/day at $0.15 KW-hour, and allowing for (say) 200 days a year effective production at this rate a ROI of anywhere from $8000/year to as much as $12000. That would amortize a $100,000 installation cost in a decade allowing for the cost of the money, and yield profits thereafter. That is actually pretty competitive with passive solar, which also has an amortization time of around a decade or bit more for consumers, although power companies probably beat that pretty substantially with their improved economies of scale. If the other "benefits" from using the water cooled system (nice trick, turning a waste heat liability almost anywhere into an "asset" add value, amortization is correspondingly lowered. Forests of these things in North Africa bordering the Mediterranean, for example, could conceivable power rapid economic development of the region while simultaneously watering the Sahara and conceivably actually altering its climate with progressive anti-desertification, while paying for themselves and even yielding a healthy long term ROI.
If they really mean 12 KW peak, then this is of course ridiculous, but that can't be right as ordinary passive PV could easily generate 120 KW peak, if not 240 KW peak with current technology, from the same 1200 m^2, and with tracking could accomplish an almost identical efficiency profile at 10 year amortization.
The top article was sufficiently messed up unitwise that I'm guessing that the author was simply clueless about this stuff. The missing number, of course, is the cost per installation. If it is less than $100K and produces an average of 288 KW-hours/day, they could range from break even with existing technology to very attractive even without "water" or "cooling" or "heating" advantages (that could easily be liabilities in locations where water for cooling is itself expensive or ecologically restricted). If it is more, well, it's an instant non-starter until they get the price down. But I'm guessing one could build these things for $100K and make money -- the concrete itself is order of $10K to $20K (including the mirrors), say $10K for the PV collector and cooling, $10K for the electronics and tracking, $30K for labor and installation -- $30K to $40K for profit at a 40% or so margin? And improvable with mass production? But I wouldn't be surprised if it were $250 K. Or $80K.
The latter is a complete waste of time. The former makes them a game changer, at least for a few years before passive PV overtakes them and renders the entire energy "crisis" moot by dropping amortization and ROI for consumer rooftop installations from around a decade plus a decade of "profit" to less than seven years and thirteen or more years of "profit". We're already on the edge of where installing rooftop solar on all new construction houses and rolling the cost into the primary mortgage is a no-brainer: "Buy a house and never pay for electricity... (for the next 20 years)" for an extra 10 or 20 thousand in price on a $250K house. Inside a decade, I fully expect to see this happen without any prodding in all parts of the US with adequate annual insolation just because it makes economic sense -- we need just one more factor of two reduction in the cost per watt of 20 year installed solar. For power companies, the amortization/ROI is largely already there in many parts of the US, and they are happily building solar farms wherever they can get cheap land near expensive electricity.
In fact, my high end.22 pellet rifle can almost certainly penetrate a skull. It goes through 5/8" plywood with ease. Certainly at the thin spots -- through the eyes, the temple -- but I certainly wouldn't bet my life that it wouldn't make it through even the thicker parts. And it's more like a.22 short or long, not even a LR in terms of muzzle velocity.
Possibly. But if it is a 2*poodle*pi, it is probably disk shaped, possibly with delicately scalloped edges. A spherical poodle seems more likely to be a (4/3)*pi*poodle-cubed, and if nothing else, being cubed is very hard on poodles. Often they subsequently turn into e^{-poodle}, a decaying poodle or (if eaten) into ex-poodle-poo.
And then there is Susskind and Black Hole Wars. In a sense, quantum mechanics already has shown that black holes in the classic sense do not exist. At least there is no entropic disconnect or loss of information.
But that is all theoretical stuff, and since we cannot really directly observe an event horizon, the best that we can say is that we can observe very distant objects that meet the mass criterion for having such a thing, if in fact the theories that predict them are correct. But an object with that same mass but no actual event horizon would, I think, look almost exactly the same from far away as far all that we can see, radiation from infalling superheated particles, is concerned. Do they pass an event horizon or asymptotically approach an almost-event horizon that never quite forms without ever technically reaching it? We'd have to capture one and examine it up close as we shot things in to -- maybe -- be able to tell the difference.
But it makes a huge difference to field theories and the effort to resolve reversible information-conserving quantum mechanics and irreversible information destroying singularities.
I spent around a year with it on at least a few of the systems I use. But I have G2 hotwired to cycle windows, open xterms, switch desktops, and fully use its autohide bars which are already laid out with everything I need and little that I don't. I do most of my work in either a browser or xterms, but I have that work in many different subjects with several windows open per subject spread out over 6 desktops that are a keystroke away. G3's window switching mechanism when I used it was arcane and enormously slow in comparison.
The real problem is that while a fork was perhaps needed, they did it wrong. G2 was close to perfect for what it was designed to do -- if nothing else its flaws were all flaws we all had worked around, and it had/has (I'm still using it, personally) some really nice features. Forking off a tablet version of Gnome is just peachy, but it should have been a TABLET VERSION fork, not an abandonment of the mainstream, widely deployed G2 in favor of a tablet friendlier interface that was enormously clunky on a non-tablet desktop or even laptop.
Sometimes there is change because it is needed, sometimes there is change for the sake of change. I sadly think that G3 is ten parts of the latter for one part of the former. Change involves pain either way, but at least one can see some advantage to doing so.
What exactly are the advantages -- not the places where yeah, with work and possibly more slowly you can make it function but actual advantages -- of G3, in particular advantages that one couldn't have implemented just as easily as new features of G2 without necessarily breaking old features that were heavily in use?
I'm not seein' a lot of those. I can launch any application I want under G2 with a key combination, for every application I ever launch, and don't even use that feature any more for anything but xterms because I use a lot of those to do work in. Window )cycling and desktop switching, though, those I use all of the time. Miniapps and application bar launchers, I use those. I don't care about animation. I don't need finger swipe screens. I don't need to have to work to find applications listed in a neat sorted order, or to have to change "views" to access certain features. I login (rarely), pop a single instance of firefox up, and from then on most of what I do is either browser based or xterm based, and I can pop an xterm up with Ctrl-Alt-P in far less than 1 second on the fly, then cycle up through a whole stack of windows with Ctrl-Shift-F to the one I want, then jump to desktop 6 (F6) to set up some music, then back to desktop 3 (F3) to work on something I'm writing, and then...
Maybe I can do all of this (and preserve the macros etc) in Mate. I suppose I should give it a try, maybe in a VM or something. Heck, maybe I'll install a full fedora VM to try it again -- I think I have the room. I used to use Fedora all the time before G3, but it was a serious show stopper.
Gnome 2 as an option (by whatever name) or only the insanity of windowing systems designed for finger-picking-tablets forced upon keystroke oriented users of actual computers doing real work in many windows on several desktops?
Otherwise, Centos 6 may end up being the last release I ever use. G2 may or may not be perfect, but I've got it more comfortable than five year old denim jeans and G3 sucked and continues to suck and AFAICT will continue to suck, forever, amen.
Slashdot Mirror
You mean, as in "read a physics textbook"?
Seriously. Depending on how much physics you've already studied, the right place to start will vary. A passable (free) intro is in my free online physics textbook http://www.phy.duke.edu/~rgb/C..., or wikipedia articles. A good intermediate treatment might be Griffiths' Classical Electrodynamics. If you want the pure quill uncut stuff, J. D. Jackson's Classical Electrodynamics is excellent, but it is not for the faint of heart or the wussy of PDE-fu.
In a nutshell, parallel currents of electric charge attract; antiparallel charged currents repel, changing charged currents radiate electromagnetic energy, and there are electrostatic forces happening in there somewhere too, in the cases where the currents are produced by unbalanced moving charge. Oh, and there is a fair bit of twistiness to the magnetic fields (called "curl") and forces, and the currents in question in "magnets" (or the general magnetic susceptibility of materials) tend to be non-dissipative (quantum) nuclear, atomic, or molecular circulations of charge, not Ohm's law type currents in a resistor. Ferromagnets in particular are what is being referred to, and they are characterized by long range order and a "permanent" magnetization in the absence of an external field below a certain temperature.
Hope this fucking helps:-)
rgb
Actually, it is Turtles. All the way down.
Oops, my bad, sorry. For some reason I added a mental decade to the year. I should have checked, as my memory ain't what it used to be, and it never was much:-)
rgb
Besides, the invention of accelerators order of 12" in size is very, very old news. The Betatron:
http://physics.illinois.edu/hi...
is, as one can see, order of a foot in diameter and could produce electrons at order of 6 MeV in 1940. Yes, that is actually before the US entered WWII and long before the invention of the cyclotron. That is gamma ~12, or v ~ 0.997 c. So if the top presentation were at all relevant to TFA it would actually be boring. One might safely conclude that it is wrong and boring.
The betatron was damn near the first particle accelerator truly worthy of the name, and was just about exactly 12" in diameter (a bit larger than that including the frame for the magnets etc) as one can clearly see in the second photo on this page if not the first.
rgb
Yeah, I've done a fair bit of time as sysadmin of several networks AND enjoy the cool stuff that comes with change and improvement in hardware and software over time.
Systemd no doubt will have growing pains associated with it, but I still remember the "growing pains" associated with kernel 2.0 (the first multiprocessor kernel) and issues with resource locking and ever so much more. Anybody want to assert that this wasn't worth it, that "single core/single processor systems were good enough for my granddad, so they are good enough for me"? Server environment or not?
Decisions like this are always about cost/benefit, risk, long term ROI. And the risks are highly exaggerated. I'm pretty certain that one will be able to squeeze system down to a slowly varying or unvarying configuration that is very conservative and stable as a rock, even with systemd. I -- mostly -- managed it with kernels that "could" decide to deadlock on some resource, and when the few mission critical exceptions to this appeared, they were aggressively resolved on the kernel lists and rapidly appeared in the community. The main thing is the locking down of the server configurations to avoid the higher risk stuff, and aggressive pursuit of problems that arise anyway, which is really no different than with init, or with Microsoft, or with Apple, or with BSD, or...
But look at the far-side benefits! Never having to give up a favorite app as long as some stable version of it once existed? That is awesome. Dynamical provisioning, possibly even across completely different operating systems? The death of the virtual machine as a standalone, resource-wasteful appliance? Sure, there may well be a world of pain between here and there, although I doubt it -- humans will almost certainly keep the pain within "tolerable" thresholds as the idea is developed, just as they did with all of the other major advances in all of the other major releases of all of the major operating systems. Change is pain, but changes that "wreck everything" are actually rare. That's what alpha/beta/early implementation are for, and we know how to use them to confine this level of pain to a select group of hacker masochists who thrive on it.
On that day, maybe just maybe, systemd will save their ass, keep them from having to replace some treasured piece of software and still be able to run on the latest hardware with up to date kernels and so on.
I've been doing Unix (with init) for a very long time at this point. I have multiple books on the Unix architecture and how to use systems commands to write fully complex software, and have written a fair pile of software using this interface. It had the advantage of simplicity and scalability. It had the disadvantage of simplicity and scalability, as the systems it runs on grew ever more complex.
Everybody is worried about "too much complexity", but Unix in general and linux in particular long, long ago passed the threshold of "insanely complex". Linux (collectively) is arguably one of the most complex things ever build by the human species. The real question is whether the integrated intelligence of the linux community is up to the task of taming the idea of systemd to where it is a benefit, not a cost, to where it enables (eventually) the transparent execution of any binary from any system on a systemd-based system, with fully automated provisioning of the libraries as needed in real time as long as they are not encumbered legally and are available securely from the net.
We deal with that now, of course, and it is so bloody complex and limiting that it totally sucks. People are constantly forced to choose between upgrading the OS/release/whatever and losing a favorite app or (shudder) figuring out how to rebuild it, in place, on the new release -- if that is even possible.
I'll suffer a bit -- differently, of course -- now in the mere hope that in five years I can run "anything" on whatever system I happen to be using and have it -- just work.
rgb
a) It's already done, and is called "wikipedia". The problem of accessing wikipedia after the solar flare in a few days wipes out human technological civilization is left as an exercise for the reader.
b) OK, so it's not really done, and is going to be even less done as paper books more or less disappear from the world and people stop learning how to read because their personal digital implant delivers content directly into your cortex in full sensory mode, all of which goes away when a nuclear war followed by a space alien invasion reduces humans to a marginal species living in abandoned mines and sewage tunnels and living on rats. Brevity is then the soul of wit. We need three things:
1) How to make and blow glass.
2) How to turn glass into lenses and lenses into microscopes and telescopes.
These two things are already sufficient. They extend human senses into the microscopic and macroscopic, otherwise hidden, Universe, and nothing but common sense and observation is required from that point on. However,
3) How to build a printing press.
is also good, provided that people can still read.
Oh, you want to rebuild civilization QUICKLY? Either we're restarting from a partial, not full, reboot (that is, we still have easy access to things like unburned oil and coal, iron, maybe a few undamaged nuclear power plants with the engineers to run them) or it's just not happening!
The problem, you see, is easy access to those resources. The more we deplete the Earth's crust of readily minable resources, the harder it is to reboot civilization on a collapse. We just don't have a lot of places where oil still comes oozing up to the surface of the Earth, for example, so why and how exactly are people going to go looking for it a kilometer or two down? How easy is it going to be to find any? Steel requires iron (still fairly plentiful, granted) and coal. Hmmm, easy coal isn't so easy any more. Easy copper, not so much. Easy aluminum? No such thing, needs massive amounts of electricity (although ore is still plentiful enough. Even making chemical reagents like sulphuric or nitric or hydrochloric acid (key to building nearly anything interesting) require sulphur, salt, electricity.
This is what is going to be tough. Bootstrapping directly from type 0 pre-civilization to type 2 civilization is going to be very difficult if we've depleted all of the easy pathways to 2 while we are type 1, even if we preserve usable copies of wikipedia, the CRC handbook, the library of congress science section, the entire proceedings of the IEEE, and a complete copy of all patents ever filed in the US patent office (and have people who can read them, and who have managed to learn calculus and build stuff). Hydroelectric power, maybe. Alcohol can drive simple motors. But going straight to nuclear or photovoltaics is going to be pretty much impossible, and going the coal/oil route we've followed the first time is going to be much, much harder.
The best thing, therefore, is to take care of the civilization we've got...
rgb
ROTFL.
Where are my mod points when I need them most... +1 Funny.
I not only have seen spectrographs of the atmospheric radiative effect, I actually own a copy of Grant Petty's book A First Course in Atmospheric Radiation", and have taught both undergrad and grad electrodynamics for over 30 years. Precisely what does this have to do with my statements above? I'm not "denying" that the greenhouse effect exists -- there is direct spectroscopic evidence for it. I can derive one simple model (a complete absorber model leading to 1.19x warming) for it on a piece of paper in three minutes. I regularly argue with people who want to claim that it doesn't exist at all, or that it violates the second law. Both are absurd -- of course it exists, and no it doesn't violate the laws of thermodynamics it is a direct consequence of them (although the actual atmospheric radiation effect is a great deal more complex than simple single layer models!)
All of this is completely irrelevant to my statements above. Let me explain the null hypothesis, since the terminology apparently eludes you. It is this: Supposed we increase atmospheric CO_2 from 300 to 600 ppm in the very simplest model planet we can imagine -- one where the only change we permit is this. One can work through the arguments for the greenhouse warming one should expect -- they involve looking at the measured spectrum of CO_2, doing a bit of work with the relevant Beers-Lambert formula, and thinking a bit about the lapse rate -- but in the end most people who do the calculation end up with somewhere between a 1 C and 1.5 C warming.
At this point one invokes the principle of ignorance -- we don't really know how the entire Earth system will respond nonlinearly to this. Nor do we have any plausible means with which to measure it -- we have no experimental Earths to do controlled observations with similar structure, e.g. 70% saltwater ocean confined in a complex pattern of continents -- and we already know that the establishment of particular circulation patterns of the confined ocean and atmosphere were the sole really plausible explanation for the Pliestocene ice age, which started when the isthmus of Panama closed between 3 and 4 million years ago.
We also know one important point from linear stability analysis. For the Earth's climate system to be stable at all, it has to respond to perturbations in forcing by opposing the change, not augmenting it. That is, at a stable point, the response to all perturbations has to be to push the system back to the stable point, not away from it, or the point isn't stable, it is unstable, like balancing a pencil on its point. This principle is taught in introductory first year physics, so presumably you are familiar with it.
The Earth's top of atmosphere "forcing" varies by roughly 90 W/m^2 every year, simply from the eccentricity of the Earth's orbit. It varies by order of a percent from fluctuations in albedo (mostly due to clouds, but also due to shrinking and expanding ice and snow fields) on a much shorter time scale, as short as days. The climate is if anything remarkably stable, at least on a short time scale (and we have the devil's own time explaining any of the longer time scale variations observed in the paleo record or the much shorter thermometric record, where the stable point itself exhibits considerable climate "drift" even while remaining sufficiently locally stable to be still considered "climate"). There is little evidence of any sort of runaway nonlinear instability from this natural variation in forcing. Quite the opposite, in fact, right up to the point where factors we do not yet really understand and cannot compute or predict seem to cause transitions like the advent of glaciation in the current, continuing, Pleistocene ice age.
Given a lack of knowledge of how the enormously complex system will respond to a small, linear variation in forcing on top of the annual periodic variation in forcing that is roughly two orders of magnitude larger and incid
Yes, you have. You missed, for example, the entire bit about the null hypothesis. You also missed the fact that I am not asserting that the Earth isn't warming, or that CO_2 increases are probably not a factor in the warming we have experienced. I can actually read a spectrograph and have a decent understanding of the GHE from the basic physics on up. I'm only pointing out that the trivial model you suggest is precisely why we should doubt that TCS is over 2 C! That is, the null hypothesis is around 1 to 1.5 C total warming from CO_2 alone, which is all we have even weak direct evidence for. Everything else is built on a shaky tower of model assumptions, physics toy models, and an attempt to solve a probably unsolvably difficult problem in a particular way to put some sort of stamp of authenticity on a conclusion that is both unfounded and so far, contradicted pretty strongly by observational fact.
rgb
One knows this because one studies nonlinear chaotic systems (in systems with far simpler coupled DEs), learns about things like the Kolmogorov scale, turbulence, Lyupanov exponents, one monkeys about with solving nonlinear coupled ODEs with both adequate and inadequate integration stepsize. From this one learns that the climate models are arguably some 30 orders of magnitude shy of a spatiotemporal step that one might reasonably expect to be able to integrate over some significant time to get an actual solution.
This gap is bridged two ways. One of the two ways is to make pure assertions about the physics in between the Kolmogorov scale and the scale we can afford to integrate. For example, forget local dynamics of thunderstorms -- thunderstorms are phenomena that are basically invisible on a 100x100x1 km grid. Assume that one can use some sort of probability distribution of thunder-storminess in the dynamics and that this is adequate to describe all of the violent and rapid heat transport vertically and laterally in thunderstorms with sizes distributed on length scales of 2 to 10 km and with time scales of significant variation of a minute or longer (the time required to get out of your car and reach the house, of course). Do this repeatedly, with everything -- tornadoes (and other small scale velocity fields with nonzero curl) -- gone, replaced with and assertion regarding averages. Don't worry about the fact that none of these assertions can be formally derived and that we know perfectly well that we won't get the right answer for any other chaotic system studied by mankind (for example, try this for a simple damped driven rigid oscillator, replace the driving force with an average of almost any sort and see what happens) thus far if we do this, but don't forget to shout that the models are based on physics if anybody dares to point this out.
The other is even better. When the models are run, they are still nonlinear iterated maps, even if they are integrated with approximated dynamics and an enormous spatiotemporal step, so they still exhibit chaos and make lots of nifty patterns that "look like" weather (and even are a theoreticaly and empirically defensible approximation to weather, for integration periods of a week or so from reasonable well-known initial conditions before the chaotic trajectories diverge to fill phase space and render them worthless for weather prediction any more). One gets, from even tiny perturbations of the initial conditions and/or physical parameters, butterfly-effect divergences that create an entire bundle of "possible microtrajectories" for the model system being solved which is, note well, not even arguably the actual equation of motion for the coupled Earth-Sun-Atmosphere-Ocean system, it is a pure toy model that nobody sane would expect to actually work. And of course it empirically does not work, not even close. The microtrajectories produced, which generally only work across a reference period (trial data) by carefully choosing large, cancelling forcing terms in the approximated dynamics, end up having far too much variance (compare to the actual climate), the wrong autocorrelation spectrum (direct evidence of the wrong physics but who is counting), and range from (for CMIP5 models) a handful that actually cool over very long time scales to some that go sky high.
The actual Earth, of course, only has one trajectory and it doesn't look anything like any of these model trajectories. So now comes the best part. The "ensemble" of microtrajectories is actually averaged and used as a prediction for the trajectory.
Words fail me. Again to fall back on a trivial example, imagine taking a damped driven rigid rod oscillator operating in the chaotic regime, starting it from an "ensemble" of slightly perturbed different initial conditions, integrating it on so coarse a timestep that one gets chaos but perhaps chaos that is not even qualitatively similar to the chaos observed with an adequate timestep, and then
Was that to me? Sorry, I have physics classes to teach and am insanely busy teaching them, and there is no point in posting a short answer to a difficult or subtle question. I had time to answer this morning and did so. Not that I expect my reply to make any difference in your beliefs. If you wish to accept the word of the climate "oracles" as god-descended truth instead of something that, well, could easily be doubted on multiple grounds I doubt that pointing those grounds out will change your beliefs. I'll merely point out that actual statisticians often make fun of climate scientists (see e.g. William Briggs' blog and his patient, detailed posts on the subject), and for pretty good reasons. Making reliable inferences from computational models in this class is something I've done a fair bit of work in, and it is very, very difficult. This isn't computing the trajectory of a baseball.
rgb
I was replying to "Here is a graph...". It states that it LOOKS like SLR is already happening (duh!) and that the rise is accelerating.
As to whether or not the future projections are based on physics: How, exactly? Do you mean that there is physics in the models used to make those projections? No argument. Are the models capable of using the physics that are in them to make a prediction of future SLR that can be falsified? Not in any possible way. Hence one integrates the models (contingent on the assumptions that go into the "physics" inside, which is often in the form of semi-empirical formulae that kind-of-work for short-run weather forecasting in the models from whence the GCMs are descended until chaos makes these predictions worthless) , observes a staggering range of possible future climates, assumes further that in this case -- more or less uniquely in the general class of problems "like" this in mathematics and physics -- it's OK to solve the problem on a spatiotemporal granularity close to 10^30th larger than the Kolmogorov scale, assumes further that even though the resulting bundle of trajectories is so broad as to be nearly useless and each one is a "possible" future history of the climate, that the mean of this bundle is a number that is somehow relevant to the future behavior of the actual climate as a single realization of a space of possibilities that is almost certainly far larger than the model space given the coarse graining and smoothing, goes one step beyond that and average over many models that aren't even independent and what -- pray to a benign deity that these are good numbers on which to bet trillions of dollars and millions of lives on right now to -- perhaps -- avoid a catastrophe later?
What part of this makes sense?
rgb
Excuse me? Seriously? The SLR since roughly 1870 is clearly published in a number of places and amounts to roughly 9 inches. Quite aside from the infinity of statistical fallacies one can generate by fitting linear trends to timeseries data: http://wmbriggs.com/blog/?p=51..., or if you prefer a longer and much more detailed statistical (Bayesian) explication of the problems: http://wmbriggs.com/blog/?p=51..., and the fact that those problems are multiplied enormously when you seek to fit a nonlinear trend to the data, to argue that this timeseries reveals "acceleration", presumably correlated with increased CO_2 near the end, in spite of the fact that its greatest visible period of "acceleration" is in the early 20th century when CO_2 levels were nearly irrelevant to any observed climate change in everybody's models is not terribly sensible.
Then we could analyze the other fallacies in this sort of graph used as an argument for 5 meter SLR by 2100. For example, the current rate of SLR is around maybe 3 cm/decade -- a bit over an inch a decade. In the 8.5 decades left in the century, we might be looking at anywhere from 8 inches to a foot of SLR based on the data as we have it now, foolishly extrapolating a linear trend indefinitely into the future for a highly nonlinear chaotic system that is perfectly capable of things like glacial transitions (either way) or century-scale droughts without any help at all from humans. However, this still doesn't do the problem justice, because of the differential probable error bars visible even in the figure you present, and the fact that the measurement methodology changes near the end, and the fact that to properly account for SLR either way one really has to take gravity and surface deformation into account in multiple ways. In particular, the crust is continuing the process of isostatic rebound resulting from the melting of an ice layer several kilometers thick on the polar regions "only" 12,000 or so years ago. The continents continue to drift. The sea bottom continues to remodel as this occurs. Much of this produces changes that we are only barely able to measure, in some places some of the time, now (mostly with satellites and e.g. GRACE, but there is a bit of chicken and egg problem there as well). There is the fact that an isostatic ocean produces LOCALIZED SLR where warm water floats on cooler water and can produce this sort of SLR in mid-ocean far from any tidal gauges. Tidal gauges in coastal areas are largely locked to local surface temperatures of the water. The satellite record includes this -- the tide gauge record does not, and since 70% of the Earth's surface is ocean, and nearly all of this ocean is "far" from continental boundaries and the comparatively tiny number of measurement stations that go back into the distant past with isostatic changes that are impossible to measure retroactively or correct for in the present, the probable error in global SLR visible in these curves is IMO at least almost certainly significantly underestimated, and that is before one gets to the factor of roughly 10 that Briggs asserts one is likely to underestimate true error by when fitting a linear trend to a timeseries.
So what the data might justify is this. The "rate" (linear trend) of SLR over the last 145 years is something like 2 plus or minus 2 mm/year -- it could be anywhere from basically 0 to as much as 4 mm/year, and this might well still underestimate the probable error. The "current rate" (measured with much better precision, but beware picking endpoints!) is perhaps order of 3 mm/year, plus or minus what, a mm/year? At least? Well within the long term average, and clearly visible as being (probably) equaled or exceeded in the past in periods with little possible correlation/causality linkage with CO_2, even in so short a record.
There isn't any conceivable argument that can be made on the basis of either s
What I still haven't seen in is just 1 climate model that explains most of the observed current and historical data.
You could have ended this sentence right there and it would be accurate. So of course any additional clause that you append isn't going to change that. However, it does make the argument contained in that clause less compelling.
rgb
Expect more AC posts like this, the power companies are paying green washers to come up with moronic arguments so people in the same tribe can re-post them thinking they actually make sense and won't look like a tool in the process:
Really. "The power companies" are paying people to blog against solar? So a company like, say, Duke Power posts a job opening somewhere and interviews candidates:
"So, we are interested in hiring somebody with excellent blogging skills."
"Oh, sure, if you observe my pale and pasty skin, my slightly overweight condition, and the callouses on my finger tips you can see that I have a long history of sitting and keyboarding instead of working. Indeed, my resume shows the same thing! Look at that -- I haven't got a single thing on there that Duke Power could possible be interested in. In fact, all I want to do is return home so I can visit my "tribe" online."
"Uh, so, why exactly are you applying for this job?"
"My mother is making me look for work! She claims that I'm stinking up the basement because I don't have time to shower or do her silly laundry while I'm busy online! Can you believe it?"
"You sound just perfect for our position. Now, let me ask you -- do you have a social conscience? I mean, is there anything you believe in very strongly -- world peace, God, the environment, racism, sexism? Oh, and I have to ask -- do you collect or distribute pictures of underage nude members of the animal kingdom more complex than arthropods on any of your computers?"
(Dazed silence.) "Uhhh, no? And, like I dunno, do anime cartoons of big-eyed sort-of-japanese nymphet ninja chicks count? They're AI, so they're probably less complex than an arthropod? Can I go now? I applied, so my mom will be happy."
"No, wait, you're hired! And before you panic, you get to work from home! Indeed, your job is going to be really simple: go online and trash-talk solar energy to your homies. But only rooftop solar. We are investing pretty heavily in solar ourselves and want to be seen by the public as being progressive (hey, we even bought out an entire power company called Progressive), but even though we are still paying people to let us load level their air conditioners in peak times, even though it is an enormous, expensive hassle to add generating capacity, even though our inclination to add more quick-online capacity would involve natural gas and hence fracking (speaking of which, how do you feel about throwing in the occasional word of praise for fracking, how it is making the world a better place and stabilizing the continental land mass so that it will eventually prevent the Big One, the next New Madrid earthquake as it were) we are terribly worried that rooftop solar will put us out of business in the next thirty years or so. We want to win the hearts and minds of America, and your online homeboys, well, they are America."
"Dude, if you call my friends `homies' one more time, I'm gonna leave and my mom can suck an oyster. Let me get this straight. All I have to do is dis rooftop solar while I'm playing my online games and visiting lame blogs and you pay me money? And I can do it from home?"
"That's it. You'll be a full-time work-at-home employee of Duke Power. Benefits and everything. You'll need to keep a log of the websites you visit to bash PV rooftop installations, and you'll have to undergo a brief training program where you learn of just how awful, dangerous, and expensive it is and how much better it is for consumers to let us install solar PV farms and continue to deliver energy safely to their wall sockets. Hey, you can even afford to move out of your mom's basement!"
"Well, OK. But nix on the moving thing -- my mom's a super cook and my Sailor Moon poster is kinda glued to the wall at this point, if you know what I mean. Thanks, Duke Power! You just hired yourself a troll! You just wait! When I get through with solar, none of my friends will even think of working out the amortizati
... because of the way MongoDB actually stores records and parses them. It is more or less a simple tree or linked list, and hence doing almost anything involves decending branches to the leaves. This is horrendously inefficient in many contexts, while still being perfectly lovely in others. Just doing a match, though, can involve a non-polynomial time search. Maybe they've improved this from when I was trying to use Mongo to drive modelling, but I doubt it as it would have involved substantially changing the way the data is actually stored and dereferenced. I had to cheat substantially in order to get anything like decent performance, and any of the SQLs outperformed it handily.
Note well that it was strictly a scaling issue. For small trees and DBs, it probably works well enough. For large DBs with millions of records and substantial structure, it is like molasses. Only worse.
rgb
I had a friend who had a Benjamin, actually, but this was back in the 60's, and yes, I was jealous as I had only a .177 break-action pellet rifle. Speciality pellet that had, as you note, a muzzle velocity "comparable" to a 22 short. Yes (Google being Our Friend), 22 LR is 1200 fps (for a reason!), a 22 short is around 1000 fps, and a Benjamin is (usually, dependent on model and mechanism) 900, which is quite respectable but depends on pellet weight.
When I decided as an Old Guy to get a really good hunting class pellet rifle I looked hard at the Benjamin-Sheridans but ended up picking the Walther Falcon Hunter edition, which is also 900 fps and fires a variety of standard or "hunting class" .22 pellets. I actually haven't tried to fire it through a 4x4 -- but who knows? I got it for my sons (really, my youngest son who is the most avid hunter) and it drops a rabbit as readily as a 22. I'm guessing that a hollow point pellet would quite possibly kill a deer shot at reasonably close range (10 yards or so and a heart or perfect head shot) -- as a 22 might -- or for that matter a human. I doubt it would "drop" either one, though and this is something I would never try with either rifle, of course, unless it is after the apocalypse and it is kill a deer with the pellet rifle or go hungry:-). In the old days I saw for myself that a daisy BB gun would leave a very painful divot in human skin without quite penetrating (no, I did not pull that particular trigger). You would not try that with the Walther as it would go clean through your leg if it didn't hit the bone, and would have a pretty good chance of chipping or breaking the bone.
The Walther, in other words, like the Benjamin Marauder etc, is definitely not a toy gun. I also have an older .177 caliber pellet gun that fires a pellet slowly enough that you can "see" it (barely) en route and one doesn't fire it at a plywood sheet as it might bounce back (or more likely, embed itself 3 mm into the wood). No comparison.
Bear in mind that it isn't just muzzle velocity, it is mass. A .22 LR is typically a 40 grain bullet, a .22 short is around 30 grain, compared to a "standard" .22 pellet at 14.3 grains and speciality hunting pellets at 20 to as much as 40 grains). The .22 LR has around 5x the kinetic energy of almost any pellet rifle out of the bore and that's a simple fact. Finally, it is ballistic drag. Pellets generally aren't fired fast enough to get sufficient stability from rifling and spin to be particularly accurate, which accounts for their "diabolo" waist. This also produces substantial drag -- it is being stabilized by drag. This means that pellet rifles have a rapid dropoff of their muzzle velocity and are really only suitable for short range hunting for any sort of larger game. Real .22 rifles get enough spin that they can avoid the skirted diabolo design, avoid much of the drag, and still have equal or better precision and ballistics. The third issue is the sound barrier. That's the thing that limits .22 muzzle velocity even in the case of the rifle -- there is substantial turbulence as a bullet passes through the sound barrier slowing down, and one needs streamlined bullet shapes like those found in centerfire rifles (which do indeed fire even .22-ish caliber highly streamlined and much more massive bullets with muzzle velocities well over the speed of sound) to have decent ballistics. Rimfire .22 LR bullets are not streamlined and are designed to shoot just under the speed of sound (or in the case of 1200 fps almost instantly drop down under it as the bullet "settles" out of the barrel) so that they usually have decent but not impressive precision (bench grouping). Competition grade guns (rimfire or pellet) usually shoot bullets at muzzle velocities deliberately well under the speed of sound -- .22 shorts, not
...Or, \pi R^2 = 3 x 400 \approx 1200 square meters of collector area (concentrated down by the mirrors). If so, the collector surface receives around 1.2 MW peak, or at 80% efficiency 960 KW converted. The 12 KW is therefore not conceivably peak, it has to be a 24 hour average -- 12*24 = 288 KW-hr, which assumes peak can be (nearly) maintained for close to 8 hours a day. This completely changes the numbers. 288 KW-hr/day is $43/day at $0.15 KW-hour, and allowing for (say) 200 days a year effective production at this rate a ROI of anywhere from $8000/year to as much as $12000. That would amortize a $100,000 installation cost in a decade allowing for the cost of the money, and yield profits thereafter. That is actually pretty competitive with passive solar, which also has an amortization time of around a decade or bit more for consumers, although power companies probably beat that pretty substantially with their improved economies of scale. If the other "benefits" from using the water cooled system (nice trick, turning a waste heat liability almost anywhere into an "asset" add value, amortization is correspondingly lowered. Forests of these things in North Africa bordering the Mediterranean, for example, could conceivable power rapid economic development of the region while simultaneously watering the Sahara and conceivably actually altering its climate with progressive anti-desertification, while paying for themselves and even yielding a healthy long term ROI.
If they really mean 12 KW peak, then this is of course ridiculous, but that can't be right as ordinary passive PV could easily generate 120 KW peak, if not 240 KW peak with current technology, from the same 1200 m^2, and with tracking could accomplish an almost identical efficiency profile at 10 year amortization.
The top article was sufficiently messed up unitwise that I'm guessing that the author was simply clueless about this stuff. The missing number, of course, is the cost per installation. If it is less than $100K and produces an average of 288 KW-hours/day, they could range from break even with existing technology to very attractive even without "water" or "cooling" or "heating" advantages (that could easily be liabilities in locations where water for cooling is itself expensive or ecologically restricted). If it is more, well, it's an instant non-starter until they get the price down. But I'm guessing one could build these things for $100K and make money -- the concrete itself is order of $10K to $20K (including the mirrors), say $10K for the PV collector and cooling, $10K for the electronics and tracking, $30K for labor and installation -- $30K to $40K for profit at a 40% or so margin? And improvable with mass production? But I wouldn't be surprised if it were $250 K. Or $80K.
The latter is a complete waste of time. The former makes them a game changer, at least for a few years before passive PV overtakes them and renders the entire energy "crisis" moot by dropping amortization and ROI for consumer rooftop installations from around a decade plus a decade of "profit" to less than seven years and thirteen or more years of "profit". We're already on the edge of where installing rooftop solar on all new construction houses and rolling the cost into the primary mortgage is a no-brainer: "Buy a house and never pay for electricity... (for the next 20 years)" for an extra 10 or 20 thousand in price on a $250K house. Inside a decade, I fully expect to see this happen without any prodding in all parts of the US with adequate annual insolation just because it makes economic sense -- we need just one more factor of two reduction in the cost per watt of 20 year installed solar. For power companies, the amortization/ROI is largely already there in many parts of the US, and they are happily building solar farms wherever they can get cheap land near expensive electricity.
rgb
In fact, my high end .22 pellet rifle can almost certainly penetrate a skull. It goes through 5/8" plywood with ease. Certainly at the thin spots -- through the eyes, the temple -- but I certainly wouldn't bet my life that it wouldn't make it through even the thicker parts. And it's more like a .22 short or long, not even a LR in terms of muzzle velocity.
Possibly. But if it is a 2*poodle*pi, it is probably disk shaped, possibly with delicately scalloped edges. A spherical poodle seems more likely to be a (4/3)*pi*poodle-cubed, and if nothing else, being cubed is very hard on poodles. Often they subsequently turn into e^{-poodle}, a decaying poodle or (if eaten) into ex-poodle-poo.
rgb
And then there is Susskind and Black Hole Wars. In a sense, quantum mechanics already has shown that black holes in the classic sense do not exist. At least there is no entropic disconnect or loss of information.
But that is all theoretical stuff, and since we cannot really directly observe an event horizon, the best that we can say is that we can observe very distant objects that meet the mass criterion for having such a thing, if in fact the theories that predict them are correct. But an object with that same mass but no actual event horizon would, I think, look almost exactly the same from far away as far all that we can see, radiation from infalling superheated particles, is concerned. Do they pass an event horizon or asymptotically approach an almost-event horizon that never quite forms without ever technically reaching it? We'd have to capture one and examine it up close as we shot things in to -- maybe -- be able to tell the difference.
But it makes a huge difference to field theories and the effort to resolve reversible information-conserving quantum mechanics and irreversible information destroying singularities.
rgb
As long as we don't have to add 4*poodle*pi, I'm happy. I doubt even a single poodle would taste very good in pi.
Other than that, I get
\Delta C = C' - C = 2\pi(R+\Delta R) - 2\pi R = 2\pi \Delta R
where \Delta R is one standard poodle, which is (curiously enough) 0.314159 meters when converted into metric. That is, a one tenth of a pi poodle.
rgb
I spent around a year with it on at least a few of the systems I use. But I have G2 hotwired to cycle windows, open xterms, switch desktops, and fully use its autohide bars which are already laid out with everything I need and little that I don't. I do most of my work in either a browser or xterms, but I have that work in many different subjects with several windows open per subject spread out over 6 desktops that are a keystroke away. G3's window switching mechanism when I used it was arcane and enormously slow in comparison.
The real problem is that while a fork was perhaps needed, they did it wrong. G2 was close to perfect for what it was designed to do -- if nothing else its flaws were all flaws we all had worked around, and it had/has (I'm still using it, personally) some really nice features. Forking off a tablet version of Gnome is just peachy, but it should have been a TABLET VERSION fork, not an abandonment of the mainstream, widely deployed G2 in favor of a tablet friendlier interface that was enormously clunky on a non-tablet desktop or even laptop.
Sometimes there is change because it is needed, sometimes there is change for the sake of change. I sadly think that G3 is ten parts of the latter for one part of the former. Change involves pain either way, but at least one can see some advantage to doing so.
What exactly are the advantages -- not the places where yeah, with work and possibly more slowly you can make it function but actual advantages -- of G3, in particular advantages that one couldn't have implemented just as easily as new features of G2 without necessarily breaking old features that were heavily in use?
I'm not seein' a lot of those. I can launch any application I want under G2 with a key combination, for every application I ever launch, and don't even use that feature any more for anything but xterms because I use a lot of those to do work in. Window )cycling and desktop switching, though, those I use all of the time. Miniapps and application bar launchers, I use those. I don't care about animation. I don't need finger swipe screens. I don't need to have to work to find applications listed in a neat sorted order, or to have to change "views" to access certain features. I login (rarely), pop a single instance of firefox up, and from then on most of what I do is either browser based or xterm based, and I can pop an xterm up with Ctrl-Alt-P in far less than 1 second on the fly, then cycle up through a whole stack of windows with Ctrl-Shift-F to the one I want, then jump to desktop 6 (F6) to set up some music, then back to desktop 3 (F3) to work on something I'm writing, and then...
Maybe I can do all of this (and preserve the macros etc) in Mate. I suppose I should give it a try, maybe in a VM or something. Heck, maybe I'll install a full fedora VM to try it again -- I think I have the room. I used to use Fedora all the time before G3, but it was a serious show stopper.
rgb
Gnome 2 as an option (by whatever name) or only the insanity of windowing systems designed for finger-picking-tablets forced upon keystroke oriented users of actual computers doing real work in many windows on several desktops?
Otherwise, Centos 6 may end up being the last release I ever use. G2 may or may not be perfect, but I've got it more comfortable than five year old denim jeans and G3 sucked and continues to suck and AFAICT will continue to suck, forever, amen.
rgb