ITER gets a lot of press, but there's an equally large obstacle to commercial fusion that it doesn't even address: the materials issues.
A commercial fusion plant is going to produce a tremendous neutron flux, orders of magnitude greater than that seen in modern fission plants. So many neutrons will be produced that every single atom in the reactor vessel is can be expected to be struck and displaced several hundred times over a 30-year life cycle, and you're actually going to get a small number of nuclear reactions that will produce minute hydrogen and helium bubbles at lattice boundaries. There are no known suitable materials that can handle that kind of neutron exposure without swelling, cracking, degrading, becoming extremely brittle, and so forth. This would be Bad.
ITER isn't going to generate the kinds of neutron flux you'd need to even explore those issues. ITER's going to generate about 3 displacements per atom, not 300. There is another facility, IFMIF, intended to research this by generating similar neutron fluxes to what you'd see in a real fusion reactor, but it's only at the design stages right now, and won't come on line for long after ITER does.
Getting the fusion right is only part of the problem, and it's possibly the easier part. It's an engineering problem. But the materials issue might not be solvable, because the right materials might just not exist.
Folks, there are huge amounts of uranium and thorium around, and we do not have time to wait until we figure out fusion to stop dumping carbon into the atmosphere. By the time we even come close to exhausting our sources of fissile fuel, we should have learned how to construct large-scale orbital structures, and once we can do that we won't even *need* fusion. It's entirely possible that commercial fusion will never happen.
And the disadvantage of Farnsworth-Hirsch type fusors is that it's not possible to use them as an energy source.
Two main categories of nonequilibrium plasmas are considered: (1) systems in which the electrons and/or fuel ions possess a significantly non-Maxwellian velocity distribution, and (2) systems in which at least two particle species, such as electrons and ions or two different species of fuel ions, are at radically different mean energies. These types of plasmas would be of particular interest for overcoming bremsstrahlung radiation losses from advanced aneutronic fuels (e.g. ^3He-^3He, p-^{11}B, and p- ^6Li) or for reducing the number of D-D side reactions in D-^3He plasmas. Analytical Fokker-Planck calculations are used to determine accurately the minimum recirculating power that must be extracted from undesirable regions of the plasma's phase space and reinjected into the proper regions of the phase space in order to counteract the effects of collisional scattering events and keep the plasma out of equilibrium. In virtually all cases, this minimum recirculating power is substantially larger than the fusion power, so barring the discovery of methods for recirculating the power at exceedingly high efficiencies, reactors employing plasmas not in thermodynamic equilibrium will not be able to produce net power.
No, seriously. Relativity says that infinite tensile strength is impossible. Everything *must* cease to act as a perfectly rigid body at some level of applied force.
Homer: Heh heh, I did it! Second in line, and all I had to do was
miss eight days of work.
Man: With the money you would have made working, you could have bought
tickets from a scalper. Homer: In theory, yes. Jerk.
Actually, basically everyone with a DSLR without dust removal has complained about this. See, in a normal camera you have hardly any moving parts. An SLR has a huge shutter, a moving mirror, and most importantly, a removable lens.
I've been using my D70 for over a year now, and have had no problems. I really don't get it; when you're changing the lens, the mirror's down, so while I could see dust getting on the mirror, that's not the CCD, and while it might show up in the viewfinder it's not going to affect the pictures.
If you take forever to change lenses, or you do it in an unusually dusty environment, sure, I could see it, but in normal use?
I spent $1200 on a 1.2 60mm prime. I have a giant blob of glass that weighs more than the camera.
Wow, are you full of shit. N=f/D. f here is 60mm, so your f/1.2 lens would have an aperture of (shudder) 50 whole millimeters.
There's no reason an aperture of 50mm would necessitate a "giant blob of glass that weighs more than the camera." None. The f/1.8 50mm Nikon and the f/1.4 50mm Nikon are both excellent lenses. They're sharp across the entire aperture range, and very distortion-free. The 1.4 has the tiniest bit of barrel wide open, but it also has better bokeh than the 1.8 because it has more diaphragm blades.
$1200 on a 1.2 60mm? You're doing nothing here but showing off the size of your epeen. There's not even a 60mm prime out there that resembles a "giant blob of glass that weighs more than the camera." Telephotos will do that when you start getting down under f/3, but a 60mm prime? No fucking way.
no one would ever take an SLR camera on a serious hike, out to a bar, mountain biking, skiing, etc.
Jesus, of course they would. What, you think Ansel Adams had some mutant teleport power that he used to just *poof* himself into position to take his shots? No, he had to *hike* out to those locations, and he did it with a lot more than an SLR, he was hauling along oodles of medium and large-format stuff. People take photos up on Everest, and they don't do it with point-and-shoots.
It is better to have some slightly less snazzy snapshots of you and your friends with a compact camera then to miss out on photographing the occasion altogether because the camera is too big to lug around.
There's a difference between snapshots and serious photography. And that's not, of course, to say that you can't produce good product with a P&S, it's more about the photographer than the tools. But the notion that SLRs are too big and bulky to take on a hike (where you've got, you know, a backpack) is silly.
The colossal outpouring of lava thought to have almost totally resurfaced Venus 500 million years ago never happened, a new study says. If correct, it means that a much longer record of Venus's history is preserved on the planet's surface.
Okay, so the previously-held theory was that Venus's surface is ~500 million years old.
But wait!
Assuming Venus was exposed to the same rain of asteroids and comets that the other planets experienced, they expected Magellan would spot about 5000 craters on the planet's surface.
But they found only about 1000, suggesting that the planet's surface is actually very young - perhaps 500 million to 1 billion years old.
So according to this new evidence, the planet's surface could be...~500 million years old.
100 billion electron volts/meter sounds like a lot. In reality, if the same amount of physical energy
*Bzzzt*. Wrong with the second sentence.
100 GeV/m isn't an amount of physical energy. It's a field strength.
It's still not a lot on a macroscopic scale (about 1.6E-8 joules per meter). But, jeeze, at least get your units right before you start doing dimensional analysis.
For the uninitiated, Orion's a nuclear pulse rocket. You have a big baseplate. You have your payload on top of the plate. You set atomic bombs off under the plate. Plate moves.
Their advanced interplanetary design had a deliverable payload the moon of 5700 tons; that's about the mass of a Los Angeles-class submarine, easily enough for a permanent manned lunar base. And not just in a single launch, in a single stage. Instead of putting men on the moon and returning them to earth by 1970, we'd have had a manned mission to Saturn (and back) by 1970.
"Oh, but you'd pollute the whole planet!" Feh. Again, look at the numbers. For the big interplanetary class, the bomb you set off at sea level is.35 kilotons. By the time you leave atmosphere, you've set off an in-atmosphere total yield of 250 kilotons.
250 kilotons is nothing. During the course of above-ground nuclear testing, the US set off a 15-megaton bomb, 60 times larger. The Soviets detonated a 50-megaton bomb. Hell, the US set off a one megaton pure fission bomb, purely to see if they could do it.
You'd launch this thing once, from a big barge in the middle of the Pacific. We'd be all over the solar system by now, instead of struggling to reinvent Apollo to go back to a place we abandoned over 30 years ago, instead of wasting hundreds of billions and too many years on a white-elephant shuttle design whose principal achievement (repairing the Hubble) would pale in comparison to the slightest thing you could do with a spacecraft capable of delivering 1300 tons to Saturn's orbit.
Feh. In the words of Old Man Murray, "It's not a lack of knowledge holding you people back, it's a lack of will."
Okay, I'm patiently waiting to find out if they've yet managed to actually enable clicking with the middle mouse button to open a link in a new tab on the Mac.
If I'm in the market to buy a car, I'm going to read reviews of the cars I'm interested in. I'm going to read a review for Car A, and another one for Car B, and another one for Car C. It's very unlikely that those reviews will compare A to B or A to C or B to C, but that doesn't stop them from being useful or informative.
The plaintiffs accuse the corporate defendants [...] of a ''civil conspiracy,'' saying they should have foreseen their entertainment ''would spawn such copycat violence"
Again, gun and knife makers know their products can be used to commit homicides in the wrong hands yet can't be held accountable so neither can the game producers.
Moreover, failure to foresee something that you should have foreseen isn't conspiracy, it's simply negligent. Conspiracy involves actually, you know, conspiring, planning for something. Failing to foresee something might mean you were negligent, but even if you did fail to foresee something, that's not anything close to conspiracy.
To be economical, the reactor realistically has to hit ignition
Ignition isn't Q=1. Breakeven is Q=1. To be economical, a D-T reactor's going to have to hit Q ~= 20; that is, 20 times as much energy coming out as you're putting in.
Ignition is what you get when the reaction sustains itself with no input energy at all; Q = infinity, basically.
Depends on the beam power. First you dazzle; you flare out the CCD obscuring any detail. More power, you trip protective circuits that tell the satellite "close off the shutter or the CCD's gonna bake" (Yes, there's not a 'shutter' in the conventional sense, but whatever, put an opaque cover over the lens assemply). More power still, you can fry the CCD.
This was the first or second. Nothing new here, except that China's involved. The Soviet Union did this to US satellites on several occasions, no big deal.
And for those who are, no doubt, going to decry the "weaponization" of space, as if there's something holy and sacred about space as compared to the sky or the oceans, again, nothing new here. We had a successfully-tested anti-satellite missile system back in the 80s, and the Soviet Union had not only anti-satellite satellites, but also an orbital battle station armed with lasers capable of blinding satellites. Yes, they actually launched it, but a malfunction caused it to deorbit shortly.
First, the Cobra. The Cobra is a great-looking airshow maneuver that has zero utility in actual air combat. It's a high-alpha maneuver that does nothing but dump a whole lot of energy and gets nothing in return. "I'll hit the brakes, he'll fly right by" is a bullshit Hollywood thing that in real combat would get you dead as the guy who "flies right by"'s wingman now has you boresighted and you have no energy to do anything with. Moreover, the notion that American aircraft can't do it is dead-on wrong. There's a well-known photo of Bill Dana, former X-15 test pilot, doing just that in an F-14. You don't need vectored thrust to do one, you need an inlet geometry that can handle the high AoA without choking off the engines.
Second, the bit about 360-degree engagement is a pure pipe dream. It is complete nonsense. Some advanced Russian aircraft have a limited degree of off-boresight engagement capability, using a head-tracking system similar to that on the AH-64 Apache, and missile seeker heads than can look around up to about 60-degrees off-boresight. The only thing I can think is that you're confusing the ability of modern IR-guided missiled to engage targets in ways other than right up the tailpipe. The SU-37 can supposedly carry a rear-firing missile, but that doesn't in any way equate to 360-degree field-of-fire.
The PS3, due in November, has gotten serious negative press in the past few months, and this refreshing good news may win back the hearts of gamers still undecided about purchasing the system."
If I'm already ambivalent about spending that much money on a game system, the question "What will the game system, which I bought to play games, do when I'm not playing games on it?" is not likely to be a significant influence on my decision.
Bruckheimer's name on a movie is a good indication that the movie is going to be *shit*.
Doesn't mean it won't make money. It might make a lot of money. But the movie is going to be *shit*.
POC2? Christ, that was like they took 5 random scripts, fired them from a cannon, picked up whatever scattered confetti they could find, decided to film it, and then lost *that*. What a rambling, insensate pile of crud. I can take that sort of "brainless fun" for an hour and a half, two hours tops, but that movie went on for *almost three hours*. Horrific.
Beverly Hills Cop 2. Bad Boys 2. Flashdance. The Rock. Con Air. Coyote Ugly. National Treasure. Armageddon. Enemy of the State.
Every single one of those sucked rancid goat anus. If that's the kind of thing that's "hit or miss," I can't imagine what you'd consider to be his hits.
Okay, Blackhawk Down. But I think that's because there'd have been a bunch of people willing and able to actually chop his balls off and feed them to him had he departed significantly from the record.
You can oversell a service, but it doesn't work with physical objects.
Bullshit. Airlines oversell seats all the time. And when they get 320 people showing up with tickets to a plane that has only 300 seats on it, they have to deal with it and make good.
But instead, they bombed highways, airports, roads and power stations.
Of course they did. How do you think Hezbollah receives arms shipments?
Any war will "affect the civilians." If you don't want your civilians affected, don't let Hezbollah use your territory to launch rockets at another nation-state.
Slashdot Mirror
ITER gets a lot of press, but there's an equally large obstacle to commercial fusion that it doesn't even address: the materials issues.
A commercial fusion plant is going to produce a tremendous neutron flux, orders of magnitude greater than that seen in modern fission plants. So many neutrons will be produced that every single atom in the reactor vessel is can be expected to be struck and displaced several hundred times over a 30-year life cycle, and you're actually going to get a small number of nuclear reactions that will produce minute hydrogen and helium bubbles at lattice boundaries. There are no known suitable materials that can handle that kind of neutron exposure without swelling, cracking, degrading, becoming extremely brittle, and so forth. This would be Bad.
ITER isn't going to generate the kinds of neutron flux you'd need to even explore those issues. ITER's going to generate about 3 displacements per atom, not 300. There is another facility, IFMIF, intended to research this by generating similar neutron fluxes to what you'd see in a real fusion reactor, but it's only at the design stages right now, and won't come on line for long after ITER does.
Getting the fusion right is only part of the problem, and it's possibly the easier part. It's an engineering problem. But the materials issue might not be solvable, because the right materials might just not exist.
Folks, there are huge amounts of uranium and thorium around, and we do not have time to wait until we figure out fusion to stop dumping carbon into the atmosphere. By the time we even come close to exhausting our sources of fissile fuel, we should have learned how to construct large-scale orbital structures, and once we can do that we won't even *need* fusion. It's entirely possible that commercial fusion will never happen.
Do we?
No, seriously. Relativity says that infinite tensile strength is impossible. Everything *must* cease to act as a perfectly rigid body at some level of applied force.
Homer: Heh heh, I did it! Second in line, and all I had to do was
miss eight days of work.
Man: With the money you would have made working, you could have bought
tickets from a scalper.
Homer: In theory, yes. Jerk.
Actually, basically everyone with a DSLR without dust removal has complained about this. See, in a normal camera you have hardly any moving parts. An SLR has a huge shutter, a moving mirror, and most importantly, a removable lens.
I've been using my D70 for over a year now, and have had no problems. I really don't get it; when you're changing the lens, the mirror's down, so while I could see dust getting on the mirror, that's not the CCD, and while it might show up in the viewfinder it's not going to affect the pictures.
If you take forever to change lenses, or you do it in an unusually dusty environment, sure, I could see it, but in normal use?
I spent $1200 on a 1.2 60mm prime. I have a giant blob of glass that weighs more than the camera.
Wow, are you full of shit. N=f/D. f here is 60mm, so your f/1.2 lens would have an aperture of (shudder) 50 whole millimeters.
There's no reason an aperture of 50mm would necessitate a "giant blob of glass that weighs more than the camera." None. The f/1.8 50mm Nikon and the f/1.4 50mm Nikon are both excellent lenses. They're sharp across the entire aperture range, and very distortion-free. The 1.4 has the tiniest bit of barrel wide open, but it also has better bokeh than the 1.8 because it has more diaphragm blades.
$1200 on a 1.2 60mm? You're doing nothing here but showing off the size of your epeen. There's not even a 60mm prime out there that resembles a "giant blob of glass that weighs more than the camera." Telephotos will do that when you start getting down under f/3, but a 60mm prime? No fucking way.
If you want to shoot movies, why wouldn't you buy a video camera?
This is like saying "Don't buy screwdrivers because they don't drive nails very well."
no one would ever take an SLR camera on a serious hike, out to a bar, mountain biking, skiing, etc.
Jesus, of course they would. What, you think Ansel Adams had some mutant teleport power that he used to just *poof* himself into position to take his shots? No, he had to *hike* out to those locations, and he did it with a lot more than an SLR, he was hauling along oodles of medium and large-format stuff. People take photos up on Everest, and they don't do it with point-and-shoots.
It is better to have some slightly less snazzy snapshots of you and your friends with a compact camera then to miss out on photographing the occasion altogether because the camera is too big to lug around.
There's a difference between snapshots and serious photography. And that's not, of course, to say that you can't produce good product with a P&S, it's more about the photographer than the tools. But the notion that SLRs are too big and bulky to take on a hike (where you've got, you know, a backpack) is silly.
(Obligatory bar photos)
Okay, so the previously-held theory was that Venus's surface is ~500 million years old.
But wait!
So according to this new evidence, the planet's surface could be...~500 million years old.
Bwuh?
100 billion electron volts/meter sounds like a lot. In reality, if the same amount of physical energy
*Bzzzt*. Wrong with the second sentence.
100 GeV/m isn't an amount of physical energy. It's a field strength.
It's still not a lot on a macroscopic scale (about 1.6E-8 joules per meter). But, jeeze, at least get your units right before you start doing dimensional analysis.
70 metric tons to orbit base
98 metric tons to orbit cargo vehicle
Ooooooh, color me completely unimpressed.
There've been some Project Orion documents declassified and published recently. Take a look.
Specifically, look at these numbers.
For the uninitiated, Orion's a nuclear pulse rocket. You have a big baseplate. You have your payload on top of the plate. You set atomic bombs off under the plate. Plate moves.
Their advanced interplanetary design had a deliverable payload the moon of 5700 tons; that's about the mass of a Los Angeles-class submarine, easily enough for a permanent manned lunar base. And not just in a single launch, in a single stage. Instead of putting men on the moon and returning them to earth by 1970, we'd have had a manned mission to Saturn (and back) by 1970.
"Oh, but you'd pollute the whole planet!" Feh. Again, look at the numbers. For the big interplanetary class, the bomb you set off at sea level is
250 kilotons is nothing. During the course of above-ground nuclear testing, the US set off a 15-megaton bomb, 60 times larger. The Soviets detonated a 50-megaton bomb. Hell, the US set off a one megaton pure fission bomb, purely to see if they could do it.
You'd launch this thing once, from a big barge in the middle of the Pacific. We'd be all over the solar system by now, instead of struggling to reinvent Apollo to go back to a place we abandoned over 30 years ago, instead of wasting hundreds of billions and too many years on a white-elephant shuttle design whose principal achievement (repairing the Hubble) would pale in comparison to the slightest thing you could do with a spacecraft capable of delivering 1300 tons to Saturn's orbit.
Feh. In the words of Old Man Murray, "It's not a lack of knowledge holding you people back, it's a lack of will."
That's going to be the epitaph for humanity.
Lyrics and sheet music. Or tab. And a flash drive with properly-tagged high-bitrate mp3s on it.
Okay, I'm patiently waiting to find out if they've yet managed to actually enable clicking with the middle mouse button to open a link in a new tab on the Mac.
Huh?
If I'm in the market to buy a car, I'm going to read reviews of the cars I'm interested in. I'm going to read a review for Car A, and another one for Car B, and another one for Car C. It's very unlikely that those reviews will compare A to B or A to C or B to C, but that doesn't stop them from being useful or informative.
The plaintiffs accuse the corporate defendants [...] of a ''civil conspiracy,'' saying they should have foreseen their entertainment ''would spawn such copycat violence"
Again, gun and knife makers know their products can be used to commit homicides in the wrong hands yet can't be held accountable so neither can the game producers.
Moreover, failure to foresee something that you should have foreseen isn't conspiracy, it's simply negligent. Conspiracy involves actually, you know, conspiring, planning for something. Failing to foresee something might mean you were negligent, but even if you did fail to foresee something, that's not anything close to conspiracy.
To be economical, the reactor realistically has to hit ignition
Ignition isn't Q=1. Breakeven is Q=1. To be economical, a D-T reactor's going to have to hit Q ~= 20; that is, 20 times as much energy coming out as you're putting in.
Ignition is what you get when the reaction sustains itself with no input energy at all; Q = infinity, basically.
Depends on the beam power. First you dazzle; you flare out the CCD obscuring any detail. More power, you trip protective circuits that tell the satellite "close off the shutter or the CCD's gonna bake" (Yes, there's not a 'shutter' in the conventional sense, but whatever, put an opaque cover over the lens assemply). More power still, you can fry the CCD.
This was the first or second. Nothing new here, except that China's involved. The Soviet Union did this to US satellites on several occasions, no big deal.
And for those who are, no doubt, going to decry the "weaponization" of space, as if there's something holy and sacred about space as compared to the sky or the oceans, again, nothing new here. We had a successfully-tested anti-satellite missile system back in the 80s, and the Soviet Union had not only anti-satellite satellites, but also an orbital battle station armed with lasers capable of blinding satellites. Yes, they actually launched it, but a malfunction caused it to deorbit shortly.
Nothing new.
2) the tax cannot be passed on to cunsumers;
If you believe that, you know nothing about economics, and I have a Bridge to Nowhere to sell you.
Hey home, I can dig it. You know he ain't gonna lay no mo' big rap up on you, man.
This post is complete and utter bollocks.
First, the Cobra. The Cobra is a great-looking airshow maneuver that has zero utility in actual air combat. It's a high-alpha maneuver that does nothing but dump a whole lot of energy and gets nothing in return. "I'll hit the brakes, he'll fly right by" is a bullshit Hollywood thing that in real combat would get you dead as the guy who "flies right by"'s wingman now has you boresighted and you have no energy to do anything with. Moreover, the notion that American aircraft can't do it is dead-on wrong. There's a well-known photo of Bill Dana, former X-15 test pilot, doing just that in an F-14. You don't need vectored thrust to do one, you need an inlet geometry that can handle the high AoA without choking off the engines.
Second, the bit about 360-degree engagement is a pure pipe dream. It is complete nonsense. Some advanced Russian aircraft have a limited degree of off-boresight engagement capability, using a head-tracking system similar to that on the AH-64 Apache, and missile seeker heads than can look around up to about 60-degrees off-boresight. The only thing I can think is that you're confusing the ability of modern IR-guided missiled to engage targets in ways other than right up the tailpipe. The SU-37 can supposedly carry a rear-firing missile, but that doesn't in any way equate to 360-degree field-of-fire.
...but the needle on my pornograph is broken and I can't find a replacement.
The PS3, due in November, has gotten serious negative press in the past few months, and this refreshing good news may win back the hearts of gamers still undecided about purchasing the system."
If I'm already ambivalent about spending that much money on a game system, the question "What will the game system, which I bought to play games, do when I'm not playing games on it?" is not likely to be a significant influence on my decision.
That guy is hit and miss.
Hit and miss?
Bruckheimer's name on a movie is a good indication that the movie is going to be *shit*.
Doesn't mean it won't make money. It might make a lot of money. But the movie is going to be *shit*.
POC2? Christ, that was like they took 5 random scripts, fired them from a cannon, picked up whatever scattered confetti they could find, decided to film it, and then lost *that*. What a rambling, insensate pile of crud. I can take that sort of "brainless fun" for an hour and a half, two hours tops, but that movie went on for *almost three hours*. Horrific.
Beverly Hills Cop 2. Bad Boys 2. Flashdance. The Rock. Con Air. Coyote Ugly. National Treasure. Armageddon. Enemy of the State.
Every single one of those sucked rancid goat anus. If that's the kind of thing that's "hit or miss," I can't imagine what you'd consider to be his hits.
Okay, Blackhawk Down. But I think that's because there'd have been a bunch of people willing and able to actually chop his balls off and feed them to him had he departed significantly from the record.
You can oversell a service, but it doesn't work with physical objects.
Bullshit. Airlines oversell seats all the time. And when they get 320 people showing up with tickets to a plane that has only 300 seats on it, they have to deal with it and make good.
But instead, they bombed highways, airports, roads and power stations.
Of course they did. How do you think Hezbollah receives arms shipments?
Any war will "affect the civilians." If you don't want your civilians affected, don't let Hezbollah use your territory to launch rockets at another nation-state.