Somehow I doubt the wave is new. It's only our understanding of it that is new. If you RTFA, you find that what's new is actually detecting evidence of it. Evidence is often (alas, not always) important in science.
If you're transferring files, TCP knocks you down several different ways. First, it treats loss as congestion and backs off way too much, and takes way too long to speed up again. Second, if the delay-bandwidth product is bigger than the window, it stalls. Both make it fail to use much of the available bandwidth, on typical high-rate lines. Worst of all, you give up a lot of capacity for in-order delivery, and file-transfer hardly benefits from in-order delivery at all. Whatever you do to TCP (and there is a long history of doing things to TCP), you're stuck with that. In any case, deploying fancy TCP means kernel hackery or funny routers, on both ends. For more details, see
Like most things, IP acceleration is better done in software. You can get all the benefit claimed for special routers or kernel drivers in user-level software by using UDP and controlling the packet injection rate and retransmission yourself. It's not even very hard to code -- unless you also want things like automatic back-off to allow incidental TCP traffic to share the line, automatic bandwidth measurement, parallel transfers (e.g. a dozen machines sharing the work to fill a 10Gbit link), file streamlining (to send whole directory trees with no delay between files), database-logged fully-acknowledged transfers, secure encryption, reliable checksumming, partial-transfer resumption, cooperative scheduled variable bandwidth limits, portability to whatever the people on the other end run, web-server and web-browser integration, GUI- or automated control and monitoring, and/or support. Then you're probably better off using a commercial product. As it happens, the movie and music studios feel that way, and they have mostly settled on the software linked from the page above.
Nowadays (e.g. since 3.x Gcc) that trick doesn't work any more,
as written. To get reliable results you would need to say
something more like
float inv_sqrt(float x) {/* death to StudlyCaps! */
float xhalf = 0.5f*x;
union { float x; int i; } ix;
ix.x = x;
ix.i = 0x5f3759df - (ix.i >> 1);
x = ix.x;
x *= 1.5f - xhalf * x * x;
return x;
}
The point is that pointer-based type punning isn't really
allowed by the language definition. The optimizer can take
advantage of that to emit simpler code that, in this case,
produces the wrong answer. Using a union short-circuits
that kind of optimization.
This isn't to say any particular Gcc produces wrong
answers with the code as written, but if you complained about
one that did, they would just laugh at you and (if they liked
you enough) tell you to rewrite it like the above instead.
The problem is that string theory is too flexible to offer specific predictions to test.
The problem is that string theorists are really mathematicians not content to subsist on maths departments' budgets, or to submit to elder mathematicians' standards of rigor. They quit doing physics two decades back.
Clearly the fusion people get this kind of money. ITER is a $12 billion project.
The fusion people aren't doing science. ITER is an engineering project meant to draw away funding that might otherwise be spent on practical, non-thermal fusion engineering projects.
I don't blame present particle physicists for the bomb; I'm only saying the bomb is why they still get so much more money spent on their projects than do other physicists. I know, too, that it's not the physicists getting most of the money, but rather the big construction contractors. I know, too, that if it isn't spent on big-ass magnets it's more likely to go for Ospreys and Viagra than to other scientists. (Not that there's anything wrong with Viagra, other than that it keeps Rush Limbaugh from committing suicide. But I digress.)
If high-energy-physicists had any questions they wanted answers to, there might be more reason to invest in expensive toys for them. As it happens, they all seem tied up doing string theory, which (notoriously) offers no predictions to test.
In the meantime, condensed-matter physicists, fluid-dynamic physicists, and plasma physicists (not to mention meteorologists, metabolic geneticists, and what-have-you) have never swung the kind of budgets you get, evidently, from having made an atom bomb once, despite that each group have collectively produced far more positive and far fewer negative effects on our daily lives.
(No, I'm not in any of those groups.)
Astronomers sometimes do swing big budgets, but they deliver astonishingly pretty pictures of stuff that really is out there -- however much they prefer to talk about stuff that's not in the pictures. Long after they've all changed their minds about the latter, we'll still have the pictures.
Speaking personally (and at deep risk of spiteful moderation) I wouldn't mind a century-long hiatus in particle-accelerator funding. There's plenty of science to be done by regular grad students at regular workbenches, and to much greater (perhaps even beneficial!) effect.
"Democrat" is not an adjective, and there is no "Democrat party", however much talk-radio fatties and the losing, indicted politicians they support, would like us to believe otherwis.
The headline on the original article said "Democrats'" with an apostrophe, which was correct. If the Slashdot editor didn't like using the possessive in the heading, then "Democratic" is the right word. That adjective comes directly from name of the party, the "Democratic Party".
A scrupulous Slashdot editor would fix the headline.
I doubt they would stay in business too long... At the company I work at we review EVERY bug report sent in and then make sure the problem is fixed as soon as possible. Maybe where I work is a fluke, but I highly doubt that.
Obviously you don't work at Microsoft. Their sales aren't affected by most bugs, so they don't fix most of them. Certainly there's no cachet in having fixed one. It was only after W2K or so that they began to get the idea that memory leaks might be a problem. Until then they figured the system would probably crash for some other reason before any leak or collection of leaks used up too much memory. They were more or less right. Maybe that was one reason not to fix crashes: without crashes they have to spend money fixing leaks, but people are already used to crashes.
I still remember my astonishment at discovering, in 1998, that the word "crash" had mutated from "stops running, needs re-boot" to "stopped running, tried to re-boot, won't boot, needs re-install". I.e., "Windows has only crashed a few times, for me; I re-installed and everything was fine again."
On Wall Street, any bug that doesn't cost millions in lost trading profits isn't considered worth bothering with. The time is better spent on features that yield millions, instead. No place in the world is friendlier to cowboy coders than Wall Street.
You mean, "could someone xerox it for me?" It's not a proper name when it's a generic term.
Google would like to claim the verb form, "google", as a trademark. Unfortunately for them, under U.S. trademark law no one can trademark a verb. Whatever the status of "Xerox", you can still xerox a piece of paper, and write that you did it, and nobody has a right to harass you about it. You can google with your browser, or you can google with your vibrator, and either way it's your business and not Google's.
Since Google can't legally enforce their preference that "googled" be their trademark, they have tried to convince people through press release. It looks as if they have succeeded, here, because no mention of the inconvenient (for them) legal status of the verb had been moderated up to the readable level at the time of this posting.
(I am not a lawyer, and this is not legal advice.)
A posting that starts out, "Dork", rated "+5, Informative"? By the evidence, any claims of persecution would be justified. However, the website the original posting refers to doesn't assert persecution, just willful ignorance. It certainly has plenty to offer anyone willing to learn something.
It's not hard to see why astronomers move heaven and earth (as it were) to avoid mentioning plasma effects:
1. The mathematics of plasma dynamics is *hard*. Not just too hard for astronomers, but too hard for everybody. Plasma physicists must do notoriously-difficult vacuum chamber experiments and months-long supercomputer simulations to get meaningful results.
2. Astronomers are, generally, self-selected from among those who don't like difficult lab work or (to a lesser extent, lately) big computer simulations. Astronomy recruits by (a) sense of wonder, (b) amazing pictures, and (c) elegant mathematics. Today's astronomers are the last people one would expect to embrace plasma physics, however necessary it might be to understanding observations.
3. In school, astronomers generally spend a semester or two on what working plasma physicists consider the phlogiston school of plasma dynamics. They learn "magnetohydrodynamics", a mathematically elegant approximation. It works OK for modeling nuclear explosions, but its simplifying assumptions are actively false in most astronomical circumstances. "It isn't what you don't know that gets you, it's what you think you know but isn't so."
Everything observable in a telescope -- aside from planets and planetesimals -- is made out of plasma, and obeys plasma-dynamic physical law. It's not hard to see why people who have learned to recognize and understand plasma phenomena, and who find it so beautifully illustrated in astronomical images, are frustrated. Press releases expose truly interesting discoveries but end up gabbling about dark matter.
It's unfortunate that the most visually appealing exposition of astronomical plasma physics, the thunderbolts.info site, is a product of catastrophism cultists. The "Electric Universe" people have mixed serious observational science with ideology that insists on treating ancient myths as observational records. Fortunately it's easy to separate back out, and they do make scientifically concrete predictions. The "Plasma Universe" model identified with Anthony Perratt, which they draw heavily upon, carefully remains within the bounds of present evidence.
Some future generation of astronomers who have studied real, physical plasma dynamics in school will be obliged to rewrite astronomy from the ground up. They will probably end up discarding dark matter and dark energy, and maybe even neutron stars and black holes, and everything written that depends on them will end up only as interesting as Newton's alchemical research. Fortunately the awe-inspiring pictures and the observational data will remain.
Am I the only one who feels sick every time some idiot reporter trots out those damned "three laws"? They're not laws of anything, and they're completely unimplementable in a real system. Asimov invented them to explore the consequences of what would seem like simple and obviously desirable rules for robots, but that had, in fact, disastrous consequences once the robots got capable enough to really apply them.
In classic fiction, runaway robots are almost always analogies for runaway social constructs -- government agencies, corporations, legal doctrines. Of course, today the corporations really have taken over the world, so cautionary tales come too late now.
My brother gave me McDevitt's "Chindi". It was easily the worst I had read in years, right from the very first line. Can't a survey ship ever find something interesting right in the middle of anything? Or is there some union regulation that says it has to be "at the extreme limit of its survey territory"? Maybe we need an SF equivalent of the Bulwer-Lytton award, named after McDevitt.
But I have to disagree about Pratchett: he's still getting better, (but don't read decide based on Monstrous Regiment.)
It makes typical astronomers very uncomfortable when it is mentioned that this is precisely the expected form of an interstellar-scale Birkeland current.
The reason typical astronomers are uncomfortable with this is that the very active field of plasma dynamics is almost entirely neglected in their education. Most are ill-equipped to evaluate or contribute to work involving real-world plasma interactions. They are handicapped not only by this neglect, but by having been taught, early on, an entirely unphysical, if mathematically elegant, substitute for plasma dynamics under which all these phenomena are supposed to be impossible.
Plasma dynamics, as a field of study, is fundamentally hard because the mathematics that describe actual, natural phenomena is entirely untractable. Practitioners depend on fiendishly difficult scaled-down high-voltage laboratory vacuum-chamber experiments, and absolutely enormous computer simulations. Astrophysicists, by a natural process, are strongly self-selected from among those with a distaste for laboratory work, and a preference for abstract, elegant mathematical constructs, so it's hardly surprising to find them disinclined to fill in the gaps in their education. Instead, certain sorts of evidence are just considered impolite to mention in their company.
(Incidentally, it is precisely this phenomenon which makes press releases about "geysers" on Enceladus -- and two-mile-wide "lava tubes" on Mars and the moon -- especially comical.)
... could plasma dynamics help explain the velocities of stars at varying distances from galactic centers that has been ascribed to dark matter?
Sort of... the velocities measured at varying distances from galactic centers are not actually, as is commonly implied, velocities of stars, but of hydrogen "gas" (plasma) in the ISM, the interstellar medium. Astronomers assume the stars move the same way as the ISM, which they might if gravitation were the only force acting on the ISM. However, since a galaxy is a disc of conductive material rotating in a magnetic field, by definition a homopolar generator as described by Lord Kelvin centuries ago, it generates galactic-scale (i.e. enormous and, in places, intense) electric fields. The fields eject charges along the axes and draw them back in along the arms. Current flowing in the arms concentrates material along its path, and at nodal points on it, via a process known as the "z-pinch". This process might have a lot to do with star formation.
It's only after matter is thoroughly concentrated and neutralized that gravitation becomes the most important force acting on it. We happen to be concentrated and neutralized ourselves, but most of the universe isn't much like us.
By the way, our own solar system is also a homopolar generator, for the same reasons, and the "solar wind" is a component of its operation. The "solar wind" is concentrated mainly in the disc of the ecliptic, and we have "jets" or "plumes" of charged particles blasting from the solar poles. Particles of the solar wind are going much faster at Jupiter's orbit than at Earth's. Of course all these "winds", "jets", and "plumes", like the "rains" of electrons Jupiter's moons experience, are astronomers' euphemisms for familiar plasma-dynamical currents in what astronomers prefer to call "hot gas".
Perhaps some future generation of astrophysicists will have taken lab courses in plasma dynamics, and will be equipped to discuss what they (and we) are seeing. The present generation is self-selected from those who, perhaps, don't much care for lab work, and who prefer physics that can be solved by pure and elegant mathematics. Unfortunately the mathematics of plasma dynamics is not elegant.
Surely you're joking. Profound effects of space plasma on satellites have been well-known (by engineers) for decades.
There's practically nothing up there but plasma. The only places in the universe that aren't practically all plasma are planets and bits of space junk, a negligible fraction of the universe's (observable) mass. Maybe you're confused because you think plasma is some sort of exotic substance. Compositionally, the only difference between a gas and a plasma is that some fraction of the atoms in a plasma are ionized. That just means one or more of the electrons that, at lower temperatures, would be bound closely in orbit around the nucleus are instead banging around loose.
That seems like a small difference, but oh! what a difference. In a familiar gas, the atoms only interact when they collide, so at very low pressures nothing much happens. In a plasma, particularly at very low pressure, the particles interact with immediate neighbors, via the electric force, at distances of centimeters, and with large masses, via magnetic forces, at distances up to light years.
Plasma dynamics, the description of how masses of plasma behave, is fiendishly complex, largely because the positive particles (nuclei) are all at least 2000 times more massive than the negative particles (electrons). As a result, anything that accelerates a nucleus at X cm/s/s blasts any electrons at more than 2000X cm/s/s the other way. Furthermore, plasmas can be neutral, or biased positive, or biased negative. When a biased plasma moves, it produces a magnetic field, and any magnetic fields it moves in affect the its motion.
Even an ionization of one in 10 000 particles is enough to make celestial stuff behave by plasma-dynamical rather than ordinary gas laws. Under rather weak electric fields, the ions accelerate enough to ionize and re-ionize the neutral atoms, a process called "entraining". Motion of biased plasma amounts to an electric current, which self-generates a magnetic field that, in turn, concentrates the current (and particles of the conductive medium) into flux tubes, called "Birkeland currents", that span solar systems (e.g. producing the Aurora) and galaxies.
The equations that describe real plasma dynamics are fiendishly complicated, and the observed behavior exhibits so many fundamental instabilities, that nobody can solve typical problems mathematically. Serious researchers fall back on computer simulations and extrapolation from vacuum-lab observations. Most fall back, instead, on a (usually) distinctly unphysical approximation known as "MHD".
Typical astronomers and astrophysicists have had a semester of MHD, where they were misled about how little it resembles any phenomenon they will ever observe. As a result, most astronomers are ill-equipped to evaluate such observations. They tend to ignore them, instead, and to discount explanations that depend on awareness of actual plasma-dynamical phenomena. This causes them two problems: they have to explain what they see using only gravitation, stellar-core fusion, and shock waves; and they have to explain why plasma dynamics has no effect on the system. Their colleagues generally give them a pass on the latter. Such common plasma-dynamical phenomena as ultraviolet and x-ray emission have traditionally been easy to ignore.
Most of the working plasma dynamicists are not involved in astrophysics, and their contribution isn't generally welcome in astrophysical journals. Of course the most vocal of the ones interested in astronomy, and thus most easily found in web searches, are highly-motivated and... interestingly quirky. Nonetheless, there's a lot to learn even from those of the catastrophism cultists who are also working physicists.
I am still confused why we need dark energy AND dark matter.
Well might you be. We need them both to prop up the Big Bang after it was falsified, over and over again, by observation. Cosmologists and astronomers have individually faced a choice, each time: ditch the only hypothesis that journals' Review Committees would allow to be mentioned in publications, or invent like crazy, ad hoc. After decades of this, the field strains under the weight of a towering edifice of pure conjecture, supported by generations of graduates and professors who know nothing else, are equipped to work on nothing else and, most importantly, dare permit nothing else to be discussed or funded.
Next time you see an astronomical press release that ends with one of the principals hoping the new observation might someday help, through some mysterious process, offer insight into the nature of dark matter, recognize the obligation to tie the work to the guild imperative. Be glad that the telescopes and space probes are built and operated by engineers. The data they collect -- and the pretty and sometimes astonishing pictures that have led us to continue funding their work, despite all -- will someday support an actual empirical theory. In the meantime, laugh.
(Parent was marked "flamebait" by some anonymous poltroon. If you disagree, reply. If you have nothing to say, move along.)
I am still confused why we need dark energy AND dark matter.
Well might you be. We need them both to prop up the Big Bang after it was falsified, over and over again, by observation. Cosmologists and astronomers have individually faced a choice, each time: ditch the only hypothesis that journals' Review Committees would allow to be mentioned in publications, or invent like crazy, ad hoc. After decades of this, the field strains under the weight of a towering edifice of pure conjecture, supported by generations of graduates and professors who know nothing else, are equipped to work on nothing else and, most importantly, dare permit nothing else to be discussed or funded.
Next time you see an astronomical press release that ends with one of the principals hoping the new observation might someday help, through some mysterious process, offer us insight into the nature of dark matter, recognize the obligation to tie the work to the guild imperative. Be glad that the telescopes and space probes are built and operated by engineers. The data they collect -- and the pretty and sometimes astonishing pictures that have led us to continue funding their work, despite all -- will someday support an actual empirical theory. In the meantime, laugh.
Electrical discharges leave a wide variety of residues, depending on details of substrate, subsurface conductivity, current density, temperature reached, and duration. Lightning on Earth tends to one extreme, which produces typical terrestrial fulgarites. On Mars, who knows?
Nobody said anything about current fractionating anything from rocks. When we look at the places where blueberries are found we find nearly pure hematite soil, the natural place to get the material for a hematite spheroid. "Lightning strike"? Is that the only sort of electrical discharge possible?
If you find the notion of electrical activity lofting dust absurd, it must be because you have paid too little attention to the analyses of Martian "dust devils", nor to recent measurements on terrestrial tornadoes. What's absurd is to imagine that Mars's atmosphere is thick enough to suspend dust in just the way it happens here.
Who said anything about "uniformly distributed in the host rock"? Who said anything about "early Mars"? Who said anything about "made of glass"? Zap the soil lying there right on the surface and see what happens. Yes, loose hematite balls.
If lightning is "less likely... in a thinner atmosphere", that means charges build up longer before it discharges, releasing more energy when it does. However, a thinner atmosphere (particles or no) is no inherent limit on lightning. What matters is ionization and dielectric breakdown. Ionization depends largely on short-wave ultraviolet exposure, which is higher on Mars because it has no ozone layer.
Incidentally, how do you imagine those "particulates flying around in the [wispy] atmosphere" get there -- thundering herds of wildebeest? Towering convection columns? The only plausible force available to loft the mass of those enormous dust storms is itself electrostatic.
"The famed 'blueberries' present in the Martian sediments are concretions. On Earth they only form in the presence of water."
In the laboratory -- i.e., on Earth -- blueberries have also been demonstrated to form in the presence of high-intensity electric arcs -- e.g., lightning. A lightning-strike on Earth releases enough energy (if efficiently employed) to excavate an 85-foot crater, but most of its energy is dissipated in the atmosphere ("boom!"). On Mars there's very little atmosphere to absorb such energy, so it's reasonable to expect a profound effect on the surface, although excavation is not necessarily the most prevalent among them. It's hard to know whether to expect more or less intense arcing on Mars; conditions are very different from Earth, and anyway Earth lightning's generative mechanism is very poorly understood (e.g. sprites were not predicted).
In fact, if you zoom into any dark area of the Martian surface (as imaged by the Global Surveyor) you'll find the darkness is composed of thousands of criscrossed black tracks of what they like to call "dust devils", which have been acknowledged to be primarily an electrical phenomenon.
Ignoring electrical phenomena presents theorists with two problems: first, they have to invent some other system to account for observations (e.g. surface water) and, second, they have to explain why the known electrical phenomena can have no observable effects, particularly not those they've just attributed to something else. Usually they dispense with the latter, and expect (rightly so far) that few will point out the omission.
As I understand it, it should take infinitely long for any bit of matter to cross the event horizon. Where does this 200,000 years come from? And, why don't we expect to find a shell of matter frozen around the outside of the event horizon?
I could guess (though they never seem to say) that they're expecting the event horizon itself to grow each time any bit of matter crosses (by whatever means), causing it to engulf just a bit more of the stuff collected just outside, in a positive feedback loop. That seems pretty fragile, particularly for an especially massive hole.
Who works these things out? Are they actually making sense, or is it all flimflam that it is to nobody's advantage to call shenanigans on? I.e., is black hole astrophysics really just science's equivalent of academic literary criticism?
And, of course, there's no such thing as "hydrogen gas" in the interstellar medium. Essentially all of it is ionized to some degree, and ionizations of one per 10,000 neutral atoms causes it to behave with dynamics fundamentally differently from neutral gas.
As a result, all this material (which collectively outmasses the stars sprinkled here and about) responds to other familiar but enormously stronger forces in addition to gravitation. Therefore, any model relying solely on gravitation will depend on such fantastical constructs as "dark matter" to match observations.
We see similar effects reported as apparent anomalies in galactic rotation, based on measurements of motion of interstellar "gas". To expect the motion of stars in a galaxy to match the motion of the plasma between them is to assume that no electromagnetic forces are in play. This is a popular assumption among astrophysicists, who as a rule never studied any real plasma dynamics in school (although they may have studied MHD, which doesn't apply), but the evidence suggests otherwise.
It's surprising that this comes out now. The origins of modern humanity were explicated just a few months ago, and the loose ends have already been tied up.
The problem has always been that there are two sorts of strong evidence: humans are almost all alike, and humans evolved in place. (E.g. early Australians were H. erectus; later they had mixed erectus and sap. characteristics; eventually the erectus features faded and vanished, leaving pure H. sap.) Naturally each had adherents who preferred to discount the others' evidence. The two have certainly seemed contradictory, up until now.
They were both right. What spread out of Africa was not actual populations of H. sap. etc., supplanting H. erectus populations that preceded them. Rather, successful gene complexes that define H. sap. spread out of Africa, upgrading local populations in-place. (Think of them as software patches.) Hardly anybody had to migrate any farther than the next village over. People married into neighboring villages, bringing their genetic advances with them, and the next generation brought them to the next village along. Of course successful genes could spread back to Africa, too, but Africa had the most variation, so produced more of the successful genes, and packaged them with more other, complementary genes.
Contrast this with the spread of agriculture into Europe, where there's evidence of farmers actually supplanting hunter/gatherers; and of course the historical record, with wholesale slaughters and genocides. (No doubt there was plenty of slaughtering earlier, but it takes technology, language, and civilized infantilization for genocides to be conducted efficiently.)
It doesn't seem like there are many other species in which this process would have worked. Bears, maybe.
Slashdot Mirror
Like most things, IP acceleration is better done in software. You can get all the benefit claimed for special routers or kernel drivers in user-level software by using UDP and controlling the packet injection rate and retransmission yourself. It's not even very hard to code -- unless you also want things like automatic back-off to allow incidental TCP traffic to share the line, automatic bandwidth measurement, parallel transfers (e.g. a dozen machines sharing the work to fill a 10Gbit link), file streamlining (to send whole directory trees with no delay between files), database-logged fully-acknowledged transfers, secure encryption, reliable checksumming, partial-transfer resumption, cooperative scheduled variable bandwidth limits, portability to whatever the people on the other end run, web-server and web-browser integration, GUI- or automated control and monitoring, and/or support. Then you're probably better off using a commercial product. As it happens, the movie and music studios feel that way, and they have mostly settled on the software linked from the page above.
Most books have a "foreword".
The point is that pointer-based type punning isn't really allowed by the language definition. The optimizer can take advantage of that to emit simpler code that, in this case, produces the wrong answer. Using a union short-circuits that kind of optimization.
This isn't to say any particular Gcc produces wrong answers with the code as written, but if you complained about one that did, they would just laugh at you and (if they liked you enough) tell you to rewrite it like the above instead.
The problem is that string theorists are really mathematicians not content to subsist on maths departments' budgets, or to submit to elder mathematicians' standards of rigor. They quit doing physics two decades back.
Clearly the fusion people get this kind of money. ITER is a $12 billion project.
The fusion people aren't doing science. ITER is an engineering project meant to draw away funding that might otherwise be spent on practical, non-thermal fusion engineering projects.
I don't blame present particle physicists for the bomb; I'm only saying the bomb is why they still get so much more money spent on their projects than do other physicists. I know, too, that it's not the physicists getting most of the money, but rather the big construction contractors. I know, too, that if it isn't spent on big-ass magnets it's more likely to go for Ospreys and Viagra than to other scientists. (Not that there's anything wrong with Viagra, other than that it keeps Rush Limbaugh from committing suicide. But I digress.)
In other words, we probably already have black holes, have had 'em like forever, and haven't even noticed 'em. (Must be like cooties.)
If high-energy-physicists had any questions they wanted answers to, there might be more reason to invest in expensive toys for them. As it happens, they all seem tied up doing string theory, which (notoriously) offers no predictions to test.
In the meantime, condensed-matter physicists, fluid-dynamic physicists, and plasma physicists (not to mention meteorologists, metabolic geneticists, and what-have-you) have never swung the kind of budgets you get, evidently, from having made an atom bomb once, despite that each group have collectively produced far more positive and far fewer negative effects on our daily lives.
(No, I'm not in any of those groups.)
Astronomers sometimes do swing big budgets, but they deliver astonishingly pretty pictures of stuff that really is out there -- however much they prefer to talk about stuff that's not in the pictures. Long after they've all changed their minds about the latter, we'll still have the pictures.
Speaking personally (and at deep risk of spiteful moderation) I wouldn't mind a century-long hiatus in particle-accelerator funding. There's plenty of science to be done by regular grad students at regular workbenches, and to much greater (perhaps even beneficial!) effect.
Not only that...
"Democrat" is not an adjective, and there is no "Democrat party",
however much talk-radio fatties and the losing, indicted politicians
they support, would like us to believe otherwis.
The headline on the original article said "Democrats'" with an
apostrophe, which was correct. If the Slashdot editor didn't like
using the possessive in the heading, then "Democratic" is the right
word. That adjective comes directly from name of the party, the
"Democratic Party".
A scrupulous Slashdot editor would fix the headline.
And, of course, no Ogg/Vorbis audio support. Next!
Seriously, this thing cries out to be hacked. Although one with stylus input would be a lot more useful, hacked.
Obviously you don't work at Microsoft. Their sales aren't affected by most bugs, so they don't fix most of them. Certainly there's no cachet in having fixed one. It was only after W2K or so that they began to get the idea that memory leaks might be a problem. Until then they figured the system would probably crash for some other reason before any leak or collection of leaks used up too much memory. They were more or less right. Maybe that was one reason not to fix crashes: without crashes they have to spend money fixing leaks, but people are already used to crashes.
I still remember my astonishment at discovering, in 1998, that the word "crash" had mutated from "stops running, needs re-boot" to "stopped running, tried to re-boot, won't boot, needs re-install". I.e., "Windows has only crashed a few times, for me; I re-installed and everything was fine again."
On Wall Street, any bug that doesn't cost millions in lost trading profits isn't considered worth bothering with. The time is better spent on features that yield millions, instead. No place in the world is friendlier to cowboy coders than Wall Street.
You mean, "could someone xerox it for me?" It's not a proper name when it's a generic term.
Google would like to claim the verb form, "google", as a trademark. Unfortunately for them, under U.S. trademark law no one can trademark a verb. Whatever the status of "Xerox", you can still xerox a piece of paper, and write that you did it, and nobody has a right to harass you about it. You can google with your browser, or you can google with your vibrator, and either way it's your business and not Google's.
Since Google can't legally enforce their preference that "googled" be their trademark, they have tried to convince people through press release. It looks as if they have succeeded, here, because no mention of the inconvenient (for them) legal status of the verb had been moderated up to the readable level at the time of this posting.
(I am not a lawyer, and this is not legal advice.)
A posting that starts out, "Dork", rated "+5, Informative"? By the evidence, any claims of persecution would be justified. However, the website the original posting refers to doesn't assert persecution, just willful ignorance. It certainly has plenty to offer anyone willing to learn something.
It's not hard to see why astronomers move heaven and earth (as it were) to avoid mentioning plasma effects:
1. The mathematics of plasma dynamics is *hard*. Not just too hard for astronomers, but too hard for everybody. Plasma physicists must do notoriously-difficult vacuum chamber experiments and months-long supercomputer simulations to get meaningful results.
2. Astronomers are, generally, self-selected from among those who don't like difficult lab work or (to a lesser extent, lately) big computer simulations. Astronomy recruits by (a) sense of wonder, (b) amazing pictures, and (c) elegant mathematics. Today's astronomers are the last people one would expect to embrace plasma physics, however necessary it might be to understanding observations.
3. In school, astronomers generally spend a semester or two on what working plasma physicists consider the phlogiston school of plasma dynamics. They learn "magnetohydrodynamics", a mathematically elegant approximation. It works OK for modeling nuclear explosions, but its simplifying assumptions are actively false in most astronomical circumstances. "It isn't what you don't know that gets you, it's what you think you know but isn't so."
Everything observable in a telescope -- aside from planets and planetesimals -- is made out of plasma, and obeys plasma-dynamic physical law. It's not hard to see why people who have learned to recognize and understand plasma phenomena, and who find it so beautifully illustrated in astronomical images, are frustrated. Press releases expose truly interesting discoveries but end up gabbling about dark matter.
It's unfortunate that the most visually appealing exposition of astronomical plasma physics, the thunderbolts.info site, is a product of catastrophism cultists. The "Electric Universe" people have mixed serious observational science with ideology that insists on treating ancient myths as observational records. Fortunately it's easy to separate back out, and they do make scientifically concrete predictions. The "Plasma Universe" model identified with Anthony Perratt, which they draw heavily upon, carefully remains within the bounds of present evidence.
Some future generation of astronomers who have studied real, physical plasma dynamics in school will be obliged to rewrite astronomy from the ground up. They will probably end up discarding dark matter and dark energy, and maybe even neutron stars and black holes, and everything written that depends on them will end up only as interesting as Newton's alchemical research. Fortunately the awe-inspiring pictures and the observational data will remain.
Am I the only one who feels sick every time some idiot reporter trots out those damned "three laws"? They're not laws of anything, and they're completely unimplementable in a real system. Asimov invented them to explore the consequences of what would seem like simple and obviously desirable rules for robots, but that had, in fact, disastrous consequences once the robots got capable enough to really apply them.
In classic fiction, runaway robots are almost always analogies for runaway social constructs -- government agencies, corporations, legal doctrines. Of course, today the corporations really have taken over the world, so cautionary tales come too late now.
My brother gave me McDevitt's "Chindi". It was easily the worst I had read in years, right from the very first line. Can't a survey ship ever find something interesting right in the middle of anything? Or is there some union regulation that says it has to be "at the extreme limit of its survey territory"? Maybe we need an SF equivalent of the Bulwer-Lytton award, named after McDevitt.
But I have to disagree about Pratchett: he's still getting better, (but don't read decide based on Monstrous Regiment.)
It makes typical astronomers very uncomfortable when it is mentioned that this is precisely the expected form of an interstellar-scale Birkeland current.
t ml
. intro.html
http://public.lanl.gov/alp/plasma/elec_currents.h
These were predicted by Alfven, and have since been detected indirectly by noting self-segregation by mass of interstellar medium ion Doppler shifts.
http://public.lanl.gov/alp/plasma/CIV.html
Similar structures have been noted in radio-telescope images, albeit not with such textbook-perfect structure.
http://public.lanl.gov/alp/plasma/plasma.universe
The reason typical astronomers are uncomfortable with this is that the very active field of plasma dynamics is almost entirely neglected in their education. Most are ill-equipped to evaluate or contribute to work involving real-world plasma interactions. They are handicapped not only by this neglect, but by having been taught, early on, an entirely unphysical, if mathematically elegant, substitute for plasma dynamics under which all these phenomena are supposed to be impossible.
Plasma dynamics, as a field of study, is fundamentally hard because the mathematics that describe actual, natural phenomena is entirely untractable. Practitioners depend on fiendishly difficult scaled-down high-voltage laboratory vacuum-chamber experiments, and absolutely enormous computer simulations. Astrophysicists, by a natural process, are strongly self-selected from among those with a distaste for laboratory work, and a preference for abstract, elegant mathematical constructs, so it's hardly surprising to find them disinclined to fill in the gaps in their education. Instead, certain sorts of evidence are just considered impolite to mention in their company.
(Incidentally, it is precisely this phenomenon which makes press releases about "geysers" on Enceladus -- and two-mile-wide "lava tubes" on Mars and the moon -- especially comical.)
Sort of... the velocities measured at varying distances from galactic centers are not actually, as is commonly implied, velocities of stars, but of hydrogen "gas" (plasma) in the ISM, the interstellar medium. Astronomers assume the stars move the same way as the ISM, which they might if gravitation were the only force acting on the ISM. However, since a galaxy is a disc of conductive material rotating in a magnetic field, by definition a homopolar generator as described by Lord Kelvin centuries ago, it generates galactic-scale (i.e. enormous and, in places, intense) electric fields. The fields eject charges along the axes and draw them back in along the arms. Current flowing in the arms concentrates material along its path, and at nodal points on it, via a process known as the "z-pinch". This process might have a lot to do with star formation.
It's only after matter is thoroughly concentrated and neutralized that gravitation becomes the most important force acting on it. We happen to be concentrated and neutralized ourselves, but most of the universe isn't much like us.
By the way, our own solar system is also a homopolar generator, for the same reasons, and the "solar wind" is a component of its operation. The "solar wind" is concentrated mainly in the disc of the ecliptic, and we have "jets" or "plumes" of charged particles blasting from the solar poles. Particles of the solar wind are going much faster at Jupiter's orbit than at Earth's. Of course all these "winds", "jets", and "plumes", like the "rains" of electrons Jupiter's moons experience, are astronomers' euphemisms for familiar plasma-dynamical currents in what astronomers prefer to call "hot gas".
Perhaps some future generation of astrophysicists will have taken lab courses in plasma dynamics, and will be equipped to discuss what they (and we) are seeing. The present generation is self-selected from those who, perhaps, don't much care for lab work, and who prefer physics that can be solved by pure and elegant mathematics. Unfortunately the mathematics of plasma dynamics is not elegant.
There's practically nothing up there but plasma. The only places in the universe that aren't practically all plasma are planets and bits of space junk, a negligible fraction of the universe's (observable) mass. Maybe you're confused because you think plasma is some sort of exotic substance. Compositionally, the only difference between a gas and a plasma is that some fraction of the atoms in a plasma are ionized. That just means one or more of the electrons that, at lower temperatures, would be bound closely in orbit around the nucleus are instead banging around loose.
That seems like a small difference, but oh! what a difference. In a familiar gas, the atoms only interact when they collide, so at very low pressures nothing much happens. In a plasma, particularly at very low pressure, the particles interact with immediate neighbors, via the electric force, at distances of centimeters, and with large masses, via magnetic forces, at distances up to light years.
Plasma dynamics, the description of how masses of plasma behave, is fiendishly complex, largely because the positive particles (nuclei) are all at least 2000 times more massive than the negative particles (electrons). As a result, anything that accelerates a nucleus at X cm/s/s blasts any electrons at more than 2000X cm/s/s the other way. Furthermore, plasmas can be neutral, or biased positive, or biased negative. When a biased plasma moves, it produces a magnetic field, and any magnetic fields it moves in affect the its motion.
Even an ionization of one in 10 000 particles is enough to make celestial stuff behave by plasma-dynamical rather than ordinary gas laws. Under rather weak electric fields, the ions accelerate enough to ionize and re-ionize the neutral atoms, a process called "entraining". Motion of biased plasma amounts to an electric current, which self-generates a magnetic field that, in turn, concentrates the current (and particles of the conductive medium) into flux tubes, called "Birkeland currents", that span solar systems (e.g. producing the Aurora) and galaxies.
The equations that describe real plasma dynamics are fiendishly complicated, and the observed behavior exhibits so many fundamental instabilities, that nobody can solve typical problems mathematically. Serious researchers fall back on computer simulations and extrapolation from vacuum-lab observations. Most fall back, instead, on a (usually) distinctly unphysical approximation known as "MHD".
Typical astronomers and astrophysicists have had a semester of MHD, where they were misled about how little it resembles any phenomenon they will ever observe. As a result, most astronomers are ill-equipped to evaluate such observations. They tend to ignore them, instead, and to discount explanations that depend on awareness of actual plasma-dynamical phenomena. This causes them two problems: they have to explain what they see using only gravitation, stellar-core fusion, and shock waves; and they have to explain why plasma dynamics has no effect on the system. Their colleagues generally give them a pass on the latter. Such common plasma-dynamical phenomena as ultraviolet and x-ray emission have traditionally been easy to ignore.
Most of the working plasma dynamicists are not involved in astrophysics, and their contribution isn't generally welcome in astrophysical journals. Of course the most vocal of the ones interested in astronomy, and thus most easily found in web searches, are highly-motivated and ... interestingly quirky. Nonetheless, there's a lot to learn even from those of the catastrophism cultists who are also working physicists.
Well might you be. We need them both to prop up the Big Bang after it was falsified, over and over again, by observation. Cosmologists and astronomers have individually faced a choice, each time: ditch the only hypothesis that journals' Review Committees would allow to be mentioned in publications, or invent like crazy, ad hoc. After decades of this, the field strains under the weight of a towering edifice of pure conjecture, supported by generations of graduates and professors who know nothing else, are equipped to work on nothing else and, most importantly, dare permit nothing else to be discussed or funded.
Next time you see an astronomical press release that ends with one of the principals hoping the new observation might someday help, through some mysterious process, offer insight into the nature of dark matter, recognize the obligation to tie the work to the guild imperative. Be glad that the telescopes and space probes are built and operated by engineers. The data they collect -- and the pretty and sometimes astonishing pictures that have led us to continue funding their work, despite all -- will someday support an actual empirical theory. In the meantime, laugh.
(Parent was marked "flamebait" by some anonymous poltroon. If you disagree, reply. If you have nothing to say, move along.)
Well might you be. We need them both to prop up the Big Bang after it was falsified, over and over again, by observation. Cosmologists and astronomers have individually faced a choice, each time: ditch the only hypothesis that journals' Review Committees would allow to be mentioned in publications, or invent like crazy, ad hoc. After decades of this, the field strains under the weight of a towering edifice of pure conjecture, supported by generations of graduates and professors who know nothing else, are equipped to work on nothing else and, most importantly, dare permit nothing else to be discussed or funded.
Next time you see an astronomical press release that ends with one of the principals hoping the new observation might someday help, through some mysterious process, offer us insight into the nature of dark matter, recognize the obligation to tie the work to the guild imperative. Be glad that the telescopes and space probes are built and operated by engineers. The data they collect -- and the pretty and sometimes astonishing pictures that have led us to continue funding their work, despite all -- will someday support an actual empirical theory. In the meantime, laugh.
Nobody said anything about current fractionating anything from rocks. When we look at the places where blueberries are found we find nearly pure hematite soil, the natural place to get the material for a hematite spheroid. "Lightning strike"? Is that the only sort of electrical discharge possible?
If you find the notion of electrical activity lofting dust absurd, it must be because you have paid too little attention to the analyses of Martian "dust devils", nor to recent measurements on terrestrial tornadoes. What's absurd is to imagine that Mars's atmosphere is thick enough to suspend dust in just the way it happens here.
If lightning is "less likely ... in a thinner atmosphere", that means charges build up longer before it discharges, releasing more energy when it does. However, a thinner atmosphere (particles or no) is no inherent limit on lightning. What matters is ionization and dielectric breakdown. Ionization depends largely on short-wave ultraviolet exposure, which is higher on Mars because it has no ozone layer.
Incidentally, how do you imagine those "particulates flying around in the [wispy] atmosphere" get there -- thundering herds of wildebeest? Towering convection columns? The only plausible force available to loft the mass of those enormous dust storms is itself electrostatic.
In the laboratory -- i.e., on Earth -- blueberries have also been demonstrated to form in the presence of high-intensity electric arcs -- e.g., lightning. A lightning-strike on Earth releases enough energy (if efficiently employed) to excavate an 85-foot crater, but most of its energy is dissipated in the atmosphere ("boom!"). On Mars there's very little atmosphere to absorb such energy, so it's reasonable to expect a profound effect on the surface, although excavation is not necessarily the most prevalent among them. It's hard to know whether to expect more or less intense arcing on Mars; conditions are very different from Earth, and anyway Earth lightning's generative mechanism is very poorly understood (e.g. sprites were not predicted).
In fact, if you zoom into any dark area of the Martian surface (as imaged by the Global Surveyor) you'll find the darkness is composed of thousands of criscrossed black tracks of what they like to call "dust devils", which have been acknowledged to be primarily an electrical phenomenon.
Ignoring electrical phenomena presents theorists with two problems: first, they have to invent some other system to account for observations (e.g. surface water) and, second, they have to explain why the known electrical phenomena can have no observable effects, particularly not those they've just attributed to something else. Usually they dispense with the latter, and expect (rightly so far) that few will point out the omission.
I could guess (though they never seem to say) that they're expecting the event horizon itself to grow each time any bit of matter crosses (by whatever means), causing it to engulf just a bit more of the stuff collected just outside, in a positive feedback loop. That seems pretty fragile, particularly for an especially massive hole.
Who works these things out? Are they actually making sense, or is it all flimflam that it is to nobody's advantage to call shenanigans on? I.e., is black hole astrophysics really just science's equivalent of academic literary criticism?
As a result, all this material (which collectively outmasses the stars sprinkled here and about) responds to other familiar but enormously stronger forces in addition to gravitation. Therefore, any model relying solely on gravitation will depend on such fantastical constructs as "dark matter" to match observations.
We see similar effects reported as apparent anomalies in galactic rotation, based on measurements of motion of interstellar "gas". To expect the motion of stars in a galaxy to match the motion of the plasma between them is to assume that no electromagnetic forces are in play. This is a popular assumption among astrophysicists, who as a rule never studied any real plasma dynamics in school (although they may have studied MHD, which doesn't apply), but the evidence suggests otherwise.
The problem has always been that there are two sorts of strong evidence: humans are almost all alike, and humans evolved in place. (E.g. early Australians were H. erectus; later they had mixed erectus and sap. characteristics; eventually the erectus features faded and vanished, leaving pure H. sap.) Naturally each had adherents who preferred to discount the others' evidence. The two have certainly seemed contradictory, up until now.
They were both right. What spread out of Africa was not actual populations of H. sap. etc., supplanting H. erectus populations that preceded them. Rather, successful gene complexes that define H. sap. spread out of Africa, upgrading local populations in-place. (Think of them as software patches.) Hardly anybody had to migrate any farther than the next village over. People married into neighboring villages, bringing their genetic advances with them, and the next generation brought them to the next village along. Of course successful genes could spread back to Africa, too, but Africa had the most variation, so produced more of the successful genes, and packaged them with more other, complementary genes.
Contrast this with the spread of agriculture into Europe, where there's evidence of farmers actually supplanting hunter/gatherers; and of course the historical record, with wholesale slaughters and genocides. (No doubt there was plenty of slaughtering earlier, but it takes technology, language, and civilized infantilization for genocides to be conducted efficiently.)
It doesn't seem like there are many other species in which this process would have worked. Bears, maybe.