Thank you, anonymous reader, for a confused summary of an idiotic blog post about a moderately dumbed-down article about an interesting article.
What they're talking about is reverse osmosis, and there's no way to make it two or three orders of magnitude more efficient. Commercial systems already hit 30% to 60% of the thermodynamic limit for energy efficiency; all graphene offers in this case is a way to increase the speed, decrease the filter size, or reduce the unnecessarily wasted energy. There's still no getting around that darned osmotic pressure.
John Graham-Cumming is the leading light behind a project...
Leading lights generally work better in front of things. I think your metaphorator might be a bit misaligned...
Yep. Looks like you've got some sinusoidal co-pleneration between the literal input shafts. Gonna have to replace your main spurving bearing, maybe the secondary too. A couple of the marzel vanes on your imagery agitator are looking a pretty worn, might want to get those replaced while you're at it.
There was a forum discussion which someone complained, "so what if I want to talk like a CBer on ham radio? As long as I'm licensed and mention my callsign every 10 min, end of transmission, bla-bla, I can talk in whatever style I want!" However, someone gave example: "That's a big ten-four good buddy and I sure do appreciate that there smokey report on the five oh niner. Well, I'll catch you on the flipper flopper!"
Bzzzzztttt. FCC Part 97 prohibits codes and ciphers used to obscure communications.
Which is thoroughly irrelevant to the issue of talking like a CBer. Nothing in your example message is a code or cipher; that's simply slang. All of it is publicly known.
The reason hams discourage talking like a CBer is that it makes you sound like one of the drooling shit-flingers who infest CB.
I think this is the comment you're referring to: 12. Bethany Says:
September 21st, 2010 at 8:20 am
Alright, here's what I calculated:
The protons are high energy with lorentz factor of gamma=7500, kinetic energy is about K=7×10^6 eV. The paper cited below says that the stopping power of a proton going 10^6 eV is about 2.5×10^8 eV cm^2 g^-1. Using the density of muscular tissue rho=1g cm^3 and the thickness of my hand of 1 cm, the energy deposited is 2.5×10^8 eV. In other units its 1.07×10^-11 calories, 4.49×10^-11 Joules, and 1×10^-14 grams of TNT. If there are hundred billion protons per bunch in the beam (as the video said) then for every bunch you get 4.49 Joules or 0.001 grams of TNT of energy. (emphasis mine)
There are two beams, each of which contains 2808 bunches. Don't worry about the effect of multiple passes, though, since there won't be any tissue left in the beam's path by the time the first pass is over.
A more informative comment showed up later: 31. Xerxes Says:
September 21st, 2010 at 10:45 am
Granted, a carbon block isn't an exact model of the human hand, but it's probably close enough. The key points are:
1) "this energy deposit over 85 s is long enough to change the density of the target material. The density decreases at the inner part of the beam heated region because of the outgoing shock waves in the transverse direction. As an example, after the impact of 200 bunches with a size of = 0.2 mm, a maximum temperature of 7000K and a density decrease by a factor of 4 is expected." The results of heating your hand to 7000K and increasing its volume by a factor of 4 are probably best not imagined. Since a full beam is 2808 bunches instead of 200, you might want to scale that by a factor of 10 too.
2) But on the other hand (hehe): "The beam tunnels through the target and deposits the energy with a penetration depth of 10 m to 15 m" Since your hand is not 10m thick, you won't pick up the full effect. This paper goes into some detail of the spatial distribution of the energy dump: http://cdsweb.cern.ch/record/972357/files/lhc-project-report-930.pdf So at hand-thickness of 2ish cm, you'd only get maybe an eighth of the effects of #1, so your hand will only reach the more modest temperature of 1000K (times 10 for a full 2808 bunches?). The shockwave from the blast will extend several cm in the transverse direction; translation, the rest of your hand will be blown off by the middle of your hand exploding. Probably the part of the accelerator apparatus downstream of your hand picks up the rest of the energy. The rest of you probably wouldn't want to be standing next to it when it blows.
(I spent so much time looking up references, several other people made the same points. Oh well.)
Note particularly the fact that if one beam hit the solid graphite beam dump without being swept around during the pass, the surface would be at 7000 C, and would be well in the process of exploding, by the time the first 200 bunches had hit. Your hand, having a lower boiling point than graphite, would begin to remove itself from the path of the beam somewhat sooner, and would therefore probably absorb rather less energy. That may be small consolation, though, since it pretty much means that the splattered remnants of your hand wouldn't be as intensely radioactive as the carbon in the beam dump would be.
As I understand it, they embed the superconducting material in a soft, non-superconducting metal like silver. There's a proximity effect at boundaries between superconductors and normal metals which allows the superconducting state to extent a short distance into the normal metal -- think of it as the Cooper pairs leaving the superconductor and taking a bit of time to notice that they're in a normal metal and split into single electrons. If the layers of normal metal between the superconducting grains are thin enough, then the supercurrent can run from one grain to the next, through the normal metal, without experiencing resistance.
The ductility of the metal allows some flexibility and tolerance for thermal expansion, as well as providing a low resistance at high temperatures. That's useful because the ceramic materials have rather high resistance when they're not superconducting, which means that if a small segment of wire warmed up above the transition temperature, its suddenly high resistance and the large current flowing through it would cause it to heat up extremely rapidly. The silver provides a secondary current path, so the wire's likely to heat up slowly enough to turn the power off before the wire melts.
Read that preprint, or at least look at the pictures -- specifically Fig. 6. It's a measurement of the upper critical field (i.e. the magnetic field that destroys the superconducting state) versus temperature. The 90% line (where the resistivity is 90% of its normal-state value) does indeed go off the graph at low temperatures; it extrapolates to about 60 T for 5 K.
There's a big difference between "This material has a very high critical field" (which is what the article said) and "This material has no critical field" (which is what the summary said).
There's no law of physics that says NiMH has to be 1.2v.
Well, it's chemistry, not physics. Look up "standard electrode potentials" sometime. Alkalines, along with carbon-zincs, produce a characteristic voltage around 1.5V per cell. NiCd and NiMH produce about 1.2V per cell. If you put two NiMH cells in series, you get 2.4V, which is more than your radio/flashlight/whatever is designed to expect from each battery. Since there's no such thing as a fraction of a cell, you're stuck with multiples of 1.2V. The solution is to buy better lights -- there's still plenty of energy left in an alkaline battery when its terminal voltage has dropped to 1.2V, and a device that craps out before then is badly designed and wastes most of the energy in your alkalines, in addition to not working with NiMHs.
Let's run Bunsen's Bullshit-O-Meter(tm) over this real quick: There are many potential ways to build quantum computers (QCs). Of these, four types have emerged as being most likely to succeed. (A)... (B)... (C)... (D)... [..........]
This is because superconductors have the unique property that very large structures can be built out of them that behave according to the rules of quantum mechanics. [*.........]
Because of this, design of superconducting QCs does not require new technology development. [**********] zzzZZZTPOP!
Damn, another fuse gone. I've gotta add better overload protection to this thing. Anyway, try telling the couple dozen research groups working on superconducting quantum computing and the millions of dollars of funding being thrown at them that the problem don't require any new technology. Once they stop laughing (which may take a while, be patient), they'll go on for a few hours about all the problems that have yet to be overcome, like getting two qubits to interact strongly enough with each other to allow logic operations, but weakly enough with the environment to make the data last long enough to be useful. Kind of a fundamental problem, that. This looks to be yet another bunch of con artists who found yet another way to make good on that old adage about fools and their money.
In other words, expect this thing's principal use to be running the Phantom Game Service.
You probably shouldn't have told law enforcement as much as you did, since they really can't act on information gathered through criminal means. They might be able to act on anonymous tips without knowing where the anonymous tipster got his info, though. I think the US immigration authorities might be interested in the fact that a green card applicant is attempting to commit international fraud. I don't know if the Canadians and British would remember that you tried to tell them about this guy before, but you might be able to send them some anonymous information also.
You'll probably never know if anything comes of this, so you won't get the satisfaction of seeing the guy get fucked. But there's a chance you could make some real trouble for him.
Note that they're found in a regular grid. Either those are some well-organized UFOs, and they bothered to hang out long enough to be under the camera in every shot, or somebody didn't clean the lens.
And I didn't even look for other maps until I'd found what looked like a containment building. Sure enough, a quick image search confirms that to be the plant.
First the nanotube article, which made the mistake of thinking "really good conductor == superconductor" and now "really low-viscosity fluid == superfluid."
Superfluid means more than low viscosity. Specifically, it indicates that the fluid is a degenarate Bose system, which the quark-gluon whateverthefuckitis is not. But the article submitter probably reads science articles in Wired and the NYT, and thinks he can throw the cool-sounding jargon around without anybody noticing that it's bullshit.
This only applies to self-assembled quantum dots. The ones created by lithography or otherwise manually constructed didn't have this problem in the first place. Don't get too excited (unless you're working with photoexcitation in self-assembled QDs, in which case this might matter to you).
-68cm CuAl sphere : I think that would be 6% Al, 94% Cu.
-Mass of 1400kg : right
-Resonant frequency 2.9kHz : right. Moreover, a passing gravitational wave of this frequency will excite oscillations in the spere, so it amplifies gravity waves at that frequency and converts them to oscillations that can be measured by more conventional sensors.
-Bandwidth of 230 Hz : Any resonant system has a particular frequency at which it likes to oscillate. A small input can cause large-amplitude oscillations if it's at or near that frequency, but will cause smaller oscillations at frequencies off resonance. The bandwidth describes how far you can get from the resonant frequency before the amplitude drops a lot. I think that's usually quoted at FWHM (full width at half-maximum), i.e. an input signal at 115 Hz or so above or below resonance will produce half the amplitude of an input exactly at resonance.
-gravitational wave antenna : right, see bit about resonant frequency.
-operate at a temperature of 20mK : right. Thermal vibrations can easily mask the ones induced by gravity waves. Make the detector colder, get less noise, see more stuff.
-quantum-limited strain : Quantum mechanics places limits on how precisely we can measure things. In this case, the absolute limit of the strain (fractional change in length, i.e. how much the sphere gets distorted) that can be observed in this thing is 4*10^-21, or 2.5 parts in 10^20. Since the observation systems aren't perfect, the actual sensitivity won't be quite that good (but will probably come close).
Redneck philosophy in a nutshell.
on
Internet Hunting
·
· Score: 5, Funny
"If you just had a gun for that."
A more concise summary of the essence of redneckhood may never have been spoken. Truly a quote for the ages.
Sure, coal plants release a lot of carbon. Some of it's C-14 (as another poster already pointed out). But you know where that carbon-14 came from? It came from the atmosphere that the dinosaurs (or trees, or diatoms, or whatever) were breathing. In fact, since the coal has been underground for so long, where it's not exposed to the cosmic rays that create the C-14 in the upper atmosphere, it contains a far lower concentration of C-14 than the CO2 you're exhaling right now.
OK, now calculate the total activity of that nuclear material. At about 0.7 microcuries per gram for natural uranium and 0.22 microcuries per gram for natural thorium, that comes out to about 3500 Ci total activity in one year, worldwide. Estimates vary, but the Soviet government estimated 90 MCi released by Chernobyl, and I think we can trust their estimate to be rather conservative. At the quoted 1982 rate, it would take coal plants better than 25,000 years to dump that much radiation into the air. Now, a lot of Chernobyl's radiation came from very short-lived isotopes - things like iodine-131. Plenty of it came from medium-lifetime, biologically nasty stuff like strontium-90, though (one estimate claimed 40 kCi of Sr-90 released in the accident).
Uranium and thorium aren't radiological hazards by any stretch of the imagination. Their toxicity as heavy metals far outweighs any danger posed my their intrinsic radioactivity. The short-lived fission fragments and neutron-activation products from nuclear power plants are much more hazardous per gram, since they don't wait 4 billion years before emitting that alpha particle.
Admittedly, the uranium and thorium will be around pretty much forever. But they're already around - the concentration in coal lower than that found in granite. Fly ash is more readily inhaled than granite, but it doesn't remain so for very long. The mercury and arsenic in the ash are much more dangerous than the radionuclides. Not that I'm trying to downplay the hazards of coal plant pollution - I don't like breathing that arsenic. But the focus should be on the materials that actually cause the harm.
But if you paste the text of that link into your browser, you find out that the package was delivered on June 22 to Tucson, AZ. I doubt that whoever's sending scam e-mails would bother to include a valid tracking number, and even if they did, the details of the package (delivered to Tucson, or at least bound there, but chances are you don't live in Tucson) should obviously betray the message as bullshit.
The Citibank one almost got me with all that stuff about checking the authenticity of the website before entering your data (using Firefox, the mouse-over text for the link doesn't display. In IE, http://citi-protection.info is a sufficient tipoff alone). Then I googled the phone number they include for checking the fingerprint -- it's the toll-free line for an erotic leather shop in Key West, FL. Either somebody working there has a legally dubious night job, or the scammer has a strange sense of humor.
I'm too lazy to even try an order of magnitude estimate for this, but I wonder how much the symmetry of the collapsing bubble is distorted by the gravitational pressure gradient. A few nanoseconds isn't much time to develop distortions, but 6 mm is damn big for this sort of thing. When the bubbles collapse back to nanometer scales, any deviation from spherical symmetry will become quite apparent. The question is whether gravity is a significant contributor to such imperfections when compared to thermal fluctuations, momentum from the incident neutrons, and the like. If so, conducting the reaction in microgravity could get the system that much closer to break-even (not that I expect they'll be close anytime soon, but it's fun to think about).
Centrifugal force is a perfectly reasonable topic for discussion, since quite a few people seem a bit fuzzy - or just plain wrong - about the idea (see other replies).
To set the record straight: A "centripetal" force is any force that causes an object to move in a circular path. When swinging something on a rope, the centripetal force is the tension in the rope. With orbiting planets, the centripetal force is gravity.
"Centrifugal force" is a fictional force invented to allow one to use Newton's laws in a rotating frame of reference (they only work properly in inertial frames, i.e. those which are neither accelerating nor rotating). It is NOT a reaction to a centripetal force - the object in question doesn't have to be moving in a circle. Let me clarify this: Say you're sitting on a merry-go-round cross-bred with an air hockey table. If you drop a puck on the (nearly frictionless) surface, what happens next depends on how fast the table is rotating. If it's not rotating, the puck sits there - the table is an inertial frame of reference in this case, so Newton's laws work without modification. If it is rotating, you'll see the puck slide toward the edge in a curved path. Somebody standing on the ground next to the table sees the puck slide in a straight line, as one would expect. But since you're sitting in a rotating reference frame, and you really like Newton's laws, you have to invent a reason to explain why the puck slides away. If you're a historically accurate dumbass, you'll call it centrifugal force.
There's actually no force involved (it's just inertia viewed from a screwed-up reference frame), so it's preferable to call it 'centrifugal acceleration.' Since acceleration is always frame-dependent, while forces supposed to be frame-independent, this term leads to somewhat less confusion and similarly fewer ignorant slashdot posts. Similar logic applies to the Coriolis effect (which the guy sitting on the table says is the reason the puck's path curves).
Michigan seems to do the same thing. It was obvious enough that the first character of the license number was the first letter of the holder's name, but I'd never thought there was any relationship to the first 3 numbers. Does anybody know the algorithm to generate the rest of a Michigan driver's license number? I've always been kinda curious about that.
But the temperature of the cold reservoir there is much lower than that attainable on Earth, since the heat is being radiated off into space. The ideal efficiency is therefore, I would guess, something better than 50% (I'd have to know the temperature produced by the radiator system to get the exact ideal efficiency). So the Voyager RTGs would operate somewhere between ~20% and ~50% of the ideal efficiency, which really isn't that bad.
Slashdot Mirror
Thank you, anonymous reader, for a confused summary of an idiotic blog post about a moderately dumbed-down article about an interesting article.
What they're talking about is reverse osmosis, and there's no way to make it two or three orders of magnitude more efficient. Commercial systems already hit 30% to 60% of the thermodynamic limit for energy efficiency; all graphene offers in this case is a way to increase the speed, decrease the filter size, or reduce the unnecessarily wasted energy. There's still no getting around that darned osmotic pressure.
John Graham-Cumming is the leading light behind a project...
Leading lights generally work better in front of things. I think your metaphorator might be a bit misaligned...
Yep. Looks like you've got some sinusoidal co-pleneration between the literal input shafts. Gonna have to replace your main spurving bearing, maybe the secondary too. A couple of the marzel vanes on your imagery agitator are looking a pretty worn, might want to get those replaced while you're at it.
Which is thoroughly irrelevant to the issue of talking like a CBer. Nothing in your example message is a code or cipher; that's simply slang. All of it is publicly known. The reason hams discourage talking like a CBer is that it makes you sound like one of the drooling shit-flingers who infest CB.
I think this is the comment you're referring to:
12. Bethany Says:
September 21st, 2010 at 8:20 am
Alright, here's what I calculated:
The protons are high energy with lorentz factor of gamma=7500, kinetic energy is about K=7×10^6 eV. The paper cited below says that the stopping power of a proton going 10^6 eV is about 2.5×10^8 eV cm^2 g^-1. Using the density of muscular tissue rho=1g cm^3 and the thickness of my hand of 1 cm, the energy deposited is 2.5×10^8 eV. In other units its 1.07×10^-11 calories, 4.49×10^-11 Joules, and 1×10^-14 grams of TNT. If there are hundred billion protons per bunch in the beam (as the video said) then for every bunch you get 4.49 Joules or 0.001 grams of TNT of energy. (emphasis mine)
There are two beams, each of which contains 2808 bunches. Don't worry about the effect of multiple passes, though, since there won't be any tissue left in the beam's path by the time the first pass is over.
A more informative comment showed up later:
31. Xerxes Says:
September 21st, 2010 at 10:45 am
I think the hand-beam question is best answered by this document: http://lsag.web.cern.ch/lsag/BeamdumpInteraction.pdf
Granted, a carbon block isn't an exact model of the human hand, but it's probably close enough. The key points are:
1) "this energy deposit over 85 s is long enough to change the density of the target material. The density decreases at the inner part of the beam heated region because of the outgoing shock waves in the transverse direction. As an example, after the impact of 200 bunches with a size of = 0.2 mm, a maximum temperature of 7000K and a density decrease by a factor of 4 is expected." The results of heating your hand to 7000K and increasing its volume by a factor of 4 are probably best not imagined. Since a full beam is 2808 bunches instead of 200, you might want to scale that by a factor of 10 too.
2) But on the other hand (hehe): "The beam tunnels through the target and deposits the energy with a penetration depth of 10 m to 15 m" Since your hand is not 10m thick, you won't pick up the full effect. This paper goes into some detail of the spatial distribution of the energy dump: http://cdsweb.cern.ch/record/972357/files/lhc-project-report-930.pdf So at hand-thickness of 2ish cm, you'd only get maybe an eighth of the effects of #1, so your hand will only reach the more modest temperature of 1000K (times 10 for a full 2808 bunches?). The shockwave from the blast will extend several cm in the transverse direction; translation, the rest of your hand will be blown off by the middle of your hand exploding. Probably the part of the accelerator apparatus downstream of your hand picks up the rest of the energy. The rest of you probably wouldn't want to be standing next to it when it blows.
Cool pictures of the effects of a low-energy (450-GeV) beam on copper plates are in http://dx.doi.org/10.1109/PAC.2005.1590851
(I spent so much time looking up references, several other people made the same points. Oh well.)
Note particularly the fact that if one beam hit the solid graphite beam dump without being swept around during the pass, the surface would be at 7000 C, and would be well in the process of exploding, by the time the first 200 bunches had hit. Your hand, having a lower boiling point than graphite, would begin to remove itself from the path of the beam somewhat sooner, and would therefore probably absorb rather less energy. That may be small consolation, though, since it pretty much means that the splattered remnants of your hand wouldn't be as intensely radioactive as the carbon in the beam dump would be.
Whoops, I just replied to the wrong comment. That should have been in response to the next comment down.
As I understand it, they embed the superconducting material in a soft, non-superconducting metal like silver. There's a proximity effect at boundaries between superconductors and normal metals which allows the superconducting state to extent a short distance into the normal metal -- think of it as the Cooper pairs leaving the superconductor and taking a bit of time to notice that they're in a normal metal and split into single electrons. If the layers of normal metal between the superconducting grains are thin enough, then the supercurrent can run from one grain to the next, through the normal metal, without experiencing resistance.
The ductility of the metal allows some flexibility and tolerance for thermal expansion, as well as providing a low resistance at high temperatures. That's useful because the ceramic materials have rather high resistance when they're not superconducting, which means that if a small segment of wire warmed up above the transition temperature, its suddenly high resistance and the large current flowing through it would cause it to heat up extremely rapidly. The silver provides a secondary current path, so the wire's likely to heat up slowly enough to turn the power off before the wire melts.
Read that preprint, or at least look at the pictures -- specifically Fig. 6. It's a measurement of the upper critical field (i.e. the magnetic field that destroys the superconducting state) versus temperature. The 90% line (where the resistivity is 90% of its normal-state value) does indeed go off the graph at low temperatures; it extrapolates to about 60 T for 5 K.
There's a big difference between "This material has a very high critical field" (which is what the article said) and "This material has no critical field" (which is what the summary said).
There's no law of physics that says NiMH has to be 1.2v.
Well, it's chemistry, not physics. Look up "standard electrode potentials" sometime. Alkalines, along with carbon-zincs, produce a characteristic voltage around 1.5V per cell. NiCd and NiMH produce about 1.2V per cell. If you put two NiMH cells in series, you get 2.4V, which is more than your radio/flashlight/whatever is designed to expect from each battery. Since there's no such thing as a fraction of a cell, you're stuck with multiples of 1.2V. The solution is to buy better lights -- there's still plenty of energy left in an alkaline battery when its terminal voltage has dropped to 1.2V, and a device that craps out before then is badly designed and wastes most of the energy in your alkalines, in addition to not working with NiMHs.
Let's run Bunsen's Bullshit-O-Meter(tm) over this real quick: ... (B) ... (C) ... (D) ...
There are many potential ways to build quantum computers (QCs). Of these, four types have emerged as being most likely to succeed. (A)
[..........]
This is because superconductors have the unique property that very large structures can be built out of them that behave according to the rules of quantum mechanics.
[*.........]
Because of this, design of superconducting QCs does not require new technology development.
[**********] zzzZZZTPOP!
Damn, another fuse gone. I've gotta add better overload protection to this thing. Anyway, try telling the couple dozen research groups working on superconducting quantum computing and the millions of dollars of funding being thrown at them that the problem don't require any new technology. Once they stop laughing (which may take a while, be patient), they'll go on for a few hours about all the problems that have yet to be overcome, like getting two qubits to interact strongly enough with each other to allow logic operations, but weakly enough with the environment to make the data last long enough to be useful. Kind of a fundamental problem, that. This looks to be yet another bunch of con artists who found yet another way to make good on that old adage about fools and their money.
In other words, expect this thing's principal use to be running the Phantom Game Service.
You'll probably never know if anything comes of this, so you won't get the satisfaction of seeing the guy get fucked. But there's a chance you could make some real trouble for him.
Note that they're found in a regular grid. Either those are some well-organized UFOs, and they bothered to hang out long enough to be under the camera in every shot, or somebody didn't clean the lens.
And I didn't even look for other maps until I'd found what looked like a containment building. Sure enough, a quick image search confirms that to be the plant.
And holy shit, I can't spell degenerate. I even previewed that...
Superfluid means more than low viscosity. Specifically, it indicates that the fluid is a degenarate Bose system, which the quark-gluon whateverthefuckitis is not. But the article submitter probably reads science articles in Wired and the NYT, and thinks he can throw the cool-sounding jargon around without anybody noticing that it's bullshit.
This only applies to self-assembled quantum dots. The ones created by lithography or otherwise manually constructed didn't have this problem in the first place. Don't get too excited (unless you're working with photoexcitation in self-assembled QDs, in which case this might matter to you).
-68cm CuAl sphere : I think that would be 6% Al, 94% Cu.
-Mass of 1400kg : right
-Resonant frequency 2.9kHz : right. Moreover, a passing gravitational wave of this frequency will excite oscillations in the spere, so it amplifies gravity waves at that frequency and converts them to oscillations that can be measured by more conventional sensors.
-Bandwidth of 230 Hz : Any resonant system has a particular frequency at which it likes to oscillate. A small input can cause large-amplitude oscillations if it's at or near that frequency, but will cause smaller oscillations at frequencies off resonance. The bandwidth describes how far you can get from the resonant frequency before the amplitude drops a lot. I think that's usually quoted at FWHM (full width at half-maximum), i.e. an input signal at 115 Hz or so above or below resonance will produce half the amplitude of an input exactly at resonance.
-gravitational wave antenna : right, see bit about resonant frequency.
-operate at a temperature of 20mK : right. Thermal vibrations can easily mask the ones induced by gravity waves. Make the detector colder, get less noise, see more stuff.
-quantum-limited strain : Quantum mechanics places limits on how precisely we can measure things. In this case, the absolute limit of the strain (fractional change in length, i.e. how much the sphere gets distorted) that can be observed in this thing is 4*10^-21, or 2.5 parts in 10^20. Since the observation systems aren't perfect, the actual sensitivity won't be quite that good (but will probably come close).
A more concise summary of the essence of redneckhood may never have been spoken. Truly a quote for the ages.
Sure, coal plants release a lot of carbon. Some of it's C-14 (as another poster already pointed out). But you know where that carbon-14 came from? It came from the atmosphere that the dinosaurs (or trees, or diatoms, or whatever) were breathing. In fact, since the coal has been underground for so long, where it's not exposed to the cosmic rays that create the C-14 in the upper atmosphere, it contains a far lower concentration of C-14 than the CO2 you're exhaling right now.
Uranium and thorium aren't radiological hazards by any stretch of the imagination. Their toxicity as heavy metals far outweighs any danger posed my their intrinsic radioactivity. The short-lived fission fragments and neutron-activation products from nuclear power plants are much more hazardous per gram, since they don't wait 4 billion years before emitting that alpha particle.
Admittedly, the uranium and thorium will be around pretty much forever. But they're already around - the concentration in coal lower than that found in granite. Fly ash is more readily inhaled than granite, but it doesn't remain so for very long. The mercury and arsenic in the ash are much more dangerous than the radionuclides. Not that I'm trying to downplay the hazards of coal plant pollution - I don't like breathing that arsenic. But the focus should be on the materials that actually cause the harm.
The Citibank one almost got me with all that stuff about checking the authenticity of the website before entering your data (using Firefox, the mouse-over text for the link doesn't display. In IE, http://citi-protection.info is a sufficient tipoff alone). Then I googled the phone number they include for checking the fingerprint -- it's the toll-free line for an erotic leather shop in Key West, FL. Either somebody working there has a legally dubious night job, or the scammer has a strange sense of humor.
I'm too lazy to even try an order of magnitude estimate for this, but I wonder how much the symmetry of the collapsing bubble is distorted by the gravitational pressure gradient. A few nanoseconds isn't much time to develop distortions, but 6 mm is damn big for this sort of thing. When the bubbles collapse back to nanometer scales, any deviation from spherical symmetry will become quite apparent. The question is whether gravity is a significant contributor to such imperfections when compared to thermal fluctuations, momentum from the incident neutrons, and the like. If so, conducting the reaction in microgravity could get the system that much closer to break-even (not that I expect they'll be close anytime soon, but it's fun to think about).
To set the record straight: A "centripetal" force is any force that causes an object to move in a circular path. When swinging something on a rope, the centripetal force is the tension in the rope. With orbiting planets, the centripetal force is gravity.
"Centrifugal force" is a fictional force invented to allow one to use Newton's laws in a rotating frame of reference (they only work properly in inertial frames, i.e. those which are neither accelerating nor rotating). It is NOT a reaction to a centripetal force - the object in question doesn't have to be moving in a circle. Let me clarify this: Say you're sitting on a merry-go-round cross-bred with an air hockey table. If you drop a puck on the (nearly frictionless) surface, what happens next depends on how fast the table is rotating. If it's not rotating, the puck sits there - the table is an inertial frame of reference in this case, so Newton's laws work without modification. If it is rotating, you'll see the puck slide toward the edge in a curved path. Somebody standing on the ground next to the table sees the puck slide in a straight line, as one would expect. But since you're sitting in a rotating reference frame, and you really like Newton's laws, you have to invent a reason to explain why the puck slides away. If you're a historically accurate dumbass, you'll call it centrifugal force.
There's actually no force involved (it's just inertia viewed from a screwed-up reference frame), so it's preferable to call it 'centrifugal acceleration.' Since acceleration is always frame-dependent, while forces supposed to be frame-independent, this term leads to somewhat less confusion and similarly fewer ignorant slashdot posts. Similar logic applies to the Coriolis effect (which the guy sitting on the table says is the reason the puck's path curves).
I've wanted to try putting silly putty in a potato gun for a while now. If you try it, let me know how what happens.
Michigan seems to do the same thing. It was obvious enough that the first character of the license number was the first letter of the holder's name, but I'd never thought there was any relationship to the first 3 numbers. Does anybody know the algorithm to generate the rest of a Michigan driver's license number? I've always been kinda curious about that.
But the temperature of the cold reservoir there is much lower than that attainable on Earth, since the heat is being radiated off into space. The ideal efficiency is therefore, I would guess, something better than 50% (I'd have to know the temperature produced by the radiator system to get the exact ideal efficiency). So the Voyager RTGs would operate somewhere between ~20% and ~50% of the ideal efficiency, which really isn't that bad.