and even ignoring all questions of whether they can generate net useful, saleable electricity... how likely do you feel that descendants of tokamaks like ITER are to produce economically viable electricity (including capital cost amortization), given their large scaling requirements, and on what sort of timeframe? What about inertial confinement alternatives based on the HiPER approach? As an ousider, it seems to me that the HiPER concept can be scaled down much more, and hence looks more attractive as a generation method.
It does not violate the 2nd law of thermodynamics beause it's not claiming to do so without energy. There is a constant energy input into the system. As Rider's work shows (Rider being the "scientist who showed..." that you mention), you can maintain fusion in a non-Maxwellian plasma but only if you selectively accelerate low energy ions instead of the bulk plasma.
Does Polywell do that? I doubt it, but I'm not versed enough to make a judgement.
I still can't believe that they'd have the gall to try to restrict all video games because they cause "violence". Makes me want to roll up his house with a giant sticky ball and launch it into the sky.
Thorium is just a trendy topic. Geeks are always so easily sold on the storyline, "There's this great new technology, and here's a list of five or so of its advantages -- it's the solution to all of the world's problems!". Which totally skims over, obviously, the disadvantages and challenges.
NIF itself isn't really the answer, though. It's great for super-dense matter studies and gathering information of use for nuclear bomb detonations, but if the goal is sustainable fusion, NIF's approach is too expensive and inefficient. Rather, you need to go with a variant like HiPER. NIF relies solely on a compression pulse. HiPER uses a compression pulse plus a heating pulse. This allows the compression pulse to be much smaller and easier to achieve.
How is this any more complicated than CE certification? How is it any easier to fake than CE certification? How is it any more complex for flight attendants than saying "If your device isn't certified for use on airplane during takeoff?" Why wouldn't manufacturers advertise the heck out of whether their products are certified or not? Why do you think that flight attendants wouldn't quickly learn the most common certified and non-certified products? Do they not talk with each other? Do they not see product ads? How is the chance of people lying and using non-certified products any worse than people who "accidentally" leave their phones or other devices on today?
Everything has an opportunity cost. What's the economic activity lost, for example, due to business travellers not being able to work during takeoff and landing?
The question is whether it actually *does* affect safety.
It should be possible to certify a device as being physically impossible to cause a problem. Calculate the maximum possible short-circuit discharge current due to capacitance in the device. Calculate the maximum interference noise on frequencies of importance. Determine whether that could disrupt communication on those frequencies in a flight-threatening manner.
One could also compare devices to other existing sources of electronic noise -- the potential discharge of say, a digital wristwatch, a static spark from moving around in the plane, static from wind blowing across aircraft flight surfaces, etc.
Even if existing devices are too high power, there should be able to be a point in which you can say, "if your device is constructed thusly, we'll let your consumers use it on a plane". And then leave it up to manufacturers to get their maximum potential sources of interference down to spec.
No, I'm talking about "" (note that you won't see it). In English, the letter is called "thorn". I linked to the wikipedia page on it earlier, but apparently you weren't looking.
Nukes in space *do* all come down to radiation. But the difference is, on Earth, the overwhelming majority of the radiation is absorbed by the atmosphere (which heats up the atmosphere, fuelling the shockwave). In space, the radiation just keeps on going. The radiation kill zone in space is many times larger than on Earth. Plus, as mentioned, radiation shiedling is far easier on earth than in space due to launch mass issues. And in case you're thinking "magnetic shielding", it indeed helps with lower-energy particles like solar wind, but doesn't do much to relativistic particles and has no effect on uncharged particles like neutrons.
It depends on how much shrapnel is coming off your comrades' ships, how much fragments of the impacted bullets are ricocheting, etc.
Some things in space will be much more muted if totally inaudible, while some will be much more prone to making noise. For example, if you're standing a thousand feet away from a bomb going off in a big bucket of sand, on the surface, that sand's probably not going to do anything to you. In space, you're going to get showered. Debris just keeps on going until it hits something.
It has meaning inside your warhead. High explosives are explosives in which the detonation (conversion of the chemicals to hot gas) occurs faster than the speed of sound in the explosive material.
Yeah, the "silent space combat" meme comes across to me akin to the "there's no ice in Iceland and no green in Greenland" meme -- things people say to try to sound smart that are based on elements of truth but which get taken too far. Sound may not travel through space, but a supersonic-propagaing sphere of compressed gas from high explosive warheads do. A missile slamming into your spaceship sure as heck is going to make some noise (even a laser ripping it up). A shower of debris from exploding craft near you is definitely going to make noise. Etc. And spacecraft are often (at least with current tech) rather noisy places to be to begin with; sound isn't dampened well. So yes, "sound" doesn't travel through space effectively, but that doesn't mean space combat will be quiet.
There are, of course, additional complexities to using lasers in space -- no show stoppers, though. The Soviets experimented with a high power chemical laser system in space. The one of the many advantages of chemical lasers is that much of the waste heat (which all high powered lasers generate in droves -- think of how much heat you want to impart to your target, now multiply it by 3-10x for laser losses and more for losses during transit) is carried off in the exhaust; they're really kind of like rocket engines. But in that regard, they also provide thrust like a rocket engine. So you have to carefully and very precisely cancel out the thrust provided by the laser when it's in operation. The exhaust also gives away your position and it's chemical signature makes obvious what you're doing (the Soviets went to great lengths to disguise the fact that they were testing a laser).
Still, laser weapons in space are an obvious choice. No need for deuterium-fluoride lasers or anything of that nature, either, since atmospheric absorption isn't an issue. Even when it comes to missiles, due to the tremendous relative speeds involved, even missiles themselves would likely just be drones that carry lasers or other equivalent weaponry.
So if you're envisioning combat to be far enough away that the light speed delay poses a problem, exactly what weapon are you envisioning that *doesn't* have this problem? If light is too slow.... Plus, if you're that far away, you're not going to be closing in on each other worth a flip. You've got plenty of time for your system to make guesses about how the target is going to move; it'll nail them sooner or later. And if you think running that laser takes a lot of power/fuel/whatever, what do you think rapidly changing the trajectory of an entire spacecraft for days on end (enough to move it out of the path of a laser in under 0.6 seconds) will consume? The reality is that if you're far enough away that light is too slow, then your combat will just be conducted closer.
Sooner or later nuclear weapons or similar would become part of space combat. There's so much empty space, true high population space colonies are so far off, and it's easy enough to set "no nukes near planets" as a MAD boundary, it seems it's going to happen. Aka, even if not a conventional nuclear weapon, with the increasing energy density demands required by space propulsion, you'll at least end up with something similar. They impose interesting constraints on space combat, as they're very different from on the ground. Almost no pressure wave, but the radiation threat is dramatically greater (nothing absorbs it and harder to block it in space)
Combat would presumably be a "you're on your own" thing. Reinforcements would take *way* too long to arrive except perhaps right near a planet or base. Space is just really, really big and most of your time in space, you're drifting or providing a constant accel.
Since all combat seems to be heading this way anyway, one might as well just say: Drones. Due to the light speed delay, they'd have to be much more automated, but again, we're headed that way anyway. Carrying around a person and a life support system is a *huge* mass and complexity penalty.
So what sort of legal framework is there that gives the libertarian water-rights owner the right to sue the fracker? "Suing" is a legal construct, and requires "legal basis" for the suit to be brought. Aka, the fracker has violated some sort of law. So in this libertarian world, we have laws about water discharge chemical levels? I thought that was the sort of stuff that libertarians hated -- laws that say what they can't dump into the land, what they can't dump into the water, what they can't dump into the air, etc.
A general takeaway from the paper: food is environmentally devastating to produce.
Combine with: exercise takes calories (basic fact; the work doesn't come from nowhere, and no, being thinner and having a reduced idle metabolic rate doesn't come close to the amount burned during exercise)
Net result: Significantly increasing (~50% or more) your daily burned calories by walking or biking several hours per day to get to your destinations is environmentally devastating. 8x so if you're not vegan, since meat takes so much water and energy to produce per unit kcal.
"Greenest" practical mode of personal transportation: low cross-section streamlined -electric- (not pedal) powered bicycle.
It's a completely retarded idea in the first place. Why add a ton of complexity to what is a simple power circuit? How much more expensive and complicated do they need to make the chargers?
"I went to my first computer conference at the New York Hilton about 20 years ago. When somebody there predicted the market for microprocessors would eventually be in the millions, someone else said, "Where are they all going to go? It's not like you need a computer in every doorknob!"
Years later, I went back to the same hotel. I noticed the room keys had been replaced by electronic cards you slide into slots in the doors.
There was a computer in every doorknob." -- Danny Hillis
You're thinking way, way too small here. "Why add a ton of complexity to a simple doorknob?" Because the benefits outweigh the costs. And the benefits in terms of smart grid usage (greater grid reliability, greater generation capacity, greater efficiency, more renewables) and safety (no power flowing until there's a secure connection with a device that can tolerate the socket's frequency and voltage -- no more "put fork in a socket, get zapped" stuff, no more sparking loose connections) easily outweigh the extra cost, especially when you consider how small the cost will be when these sockets are churned out in Chinese factories by the billions. The cost of the socket hardware itself isn't even the main cost in installing a socket, not by a long shot. The addition of a 10-cent microchip-controlled switch (which is probably how much this will cost if the level of bulk you can get from mandating said sockets in the electrical code came to be) wouldn't even be noticed.
The US learned a frustrating lesson about this in the 1980s when they discovered that this was precisely how the Soviets were listening into our communications in our war games exercises.
Of course, we had a number of fun ways to listen in on them that they either didn't know about or kept forgetting about. Like how, for example, the radio signals on early mobile phones didn't just propagate laterally (which they were very careful about), but also up. And can be heard from really far up, if you have a good enough ear in orbit;)
It was always fun, chatting with an old friend who served in military intelligence during the Cold War.
Graphite does burn in some circumstances, and it's a myth that it does not.
* Fresh, pure graphite under atmospheric conditions with no additional source of heat will erode at high temperatures, but not self-sustain. Which is still quite bad.
* Any alteration to those starting conditions can yield a self-sustaining graphite fire. That is, A) alteration to the graphite structure due to long periods of intense radiation bombardment and/or infiltration, B) significant impurities or defects in the graphite during production, C) non-atmospheric conditions, such as high temperature steam instead of just air, or elevated pressures, D) continued input of nuclear decay heat, self-sustaining the erosion process as an effective continuous burn.
Your steel mill is a great example, as they're constantly burning through graphite electrodes (each lasts only about a week). To reiterate the significance of that: if that were nuclear core material, it'd all be in the air in a week.
When you think about it, this is the ultimate way for a rich person to use their money to flip the bird at other cars as they go by.
* My car is bigger than yours! * My car is cooler than yours! * My car is faster than yours! * My car is greener than yours!
Etc, all at once. The other car might possibly best them in one category, but definitely not all. You just *know* there are plenty of rich people who would throw down money on something like that.
Slashdot Mirror
and even ignoring all questions of whether they can generate net useful, saleable electricity... how likely do you feel that descendants of tokamaks like ITER are to produce economically viable electricity (including capital cost amortization), given their large scaling requirements, and on what sort of timeframe? What about inertial confinement alternatives based on the HiPER approach? As an ousider, it seems to me that the HiPER concept can be scaled down much more, and hence looks more attractive as a generation method.
It does not violate the 2nd law of thermodynamics beause it's not claiming to do so without energy. There is a constant energy input into the system. As Rider's work shows (Rider being the "scientist who showed..." that you mention), you can maintain fusion in a non-Maxwellian plasma but only if you selectively accelerate low energy ions instead of the bulk plasma.
Does Polywell do that? I doubt it, but I'm not versed enough to make a judgement.
I still can't believe that they'd have the gall to try to restrict all video games because they cause "violence". Makes me want to roll up his house with a giant sticky ball and launch it into the sky.
Thorium is just a trendy topic. Geeks are always so easily sold on the storyline, "There's this great new technology, and here's a list of five or so of its advantages -- it's the solution to all of the world's problems!". Which totally skims over, obviously, the disadvantages and challenges.
They don't.
Next question?
NIF itself isn't really the answer, though. It's great for super-dense matter studies and gathering information of use for nuclear bomb detonations, but if the goal is sustainable fusion, NIF's approach is too expensive and inefficient. Rather, you need to go with a variant like HiPER. NIF relies solely on a compression pulse. HiPER uses a compression pulse plus a heating pulse. This allows the compression pulse to be much smaller and easier to achieve.
How is this any more complicated than CE certification?
How is it any easier to fake than CE certification?
How is it any more complex for flight attendants than saying "If your device isn't certified for use on airplane during takeoff?"
Why wouldn't manufacturers advertise the heck out of whether their products are certified or not?
Why do you think that flight attendants wouldn't quickly learn the most common certified and non-certified products? Do they not talk with each other? Do they not see product ads?
How is the chance of people lying and using non-certified products any worse than people who "accidentally" leave their phones or other devices on today?
Everything has an opportunity cost. What's the economic activity lost, for example, due to business travellers not being able to work during takeoff and landing?
The question is whether it actually *does* affect safety.
It should be possible to certify a device as being physically impossible to cause a problem. Calculate the maximum possible short-circuit discharge current due to capacitance in the device. Calculate the maximum interference noise on frequencies of importance. Determine whether that could disrupt communication on those frequencies in a flight-threatening manner.
One could also compare devices to other existing sources of electronic noise -- the potential discharge of say, a digital wristwatch, a static spark from moving around in the plane, static from wind blowing across aircraft flight surfaces, etc.
Even if existing devices are too high power, there should be able to be a point in which you can say, "if your device is constructed thusly, we'll let your consumers use it on a plane". And then leave it up to manufacturers to get their maximum potential sources of interference down to spec.
No, I'm talking about "" (note that you won't see it). In English, the letter is called "thorn". I linked to the wikipedia page on it earlier, but apparently you weren't looking.
Nukes in space *do* all come down to radiation. But the difference is, on Earth, the overwhelming majority of the radiation is absorbed by the atmosphere (which heats up the atmosphere, fuelling the shockwave). In space, the radiation just keeps on going. The radiation kill zone in space is many times larger than on Earth. Plus, as mentioned, radiation shiedling is far easier on earth than in space due to launch mass issues. And in case you're thinking "magnetic shielding", it indeed helps with lower-energy particles like solar wind, but doesn't do much to relativistic particles and has no effect on uncharged particles like neutrons.
It depends on how much shrapnel is coming off your comrades' ships, how much fragments of the impacted bullets are ricocheting, etc.
Some things in space will be much more muted if totally inaudible, while some will be much more prone to making noise. For example, if you're standing a thousand feet away from a bomb going off in a big bucket of sand, on the surface, that sand's probably not going to do anything to you. In space, you're going to get showered. Debris just keeps on going until it hits something.
It has meaning inside your warhead. High explosives are explosives in which the detonation (conversion of the chemicals to hot gas) occurs faster than the speed of sound in the explosive material.
Ohhh... right. Slashdot is stuck in the mid-1990s and can't handle Unicode properly. The letter that magically disappeared from my post is this.
It's an experimental GUI. Go with something unexpected, like Icelandic. Plus, the letter makes for better emoticons than P. Example:
.
. :
Yeah, the "silent space combat" meme comes across to me akin to the "there's no ice in Iceland and no green in Greenland" meme -- things people say to try to sound smart that are based on elements of truth but which get taken too far. Sound may not travel through space, but a supersonic-propagaing sphere of compressed gas from high explosive warheads do. A missile slamming into your spaceship sure as heck is going to make some noise (even a laser ripping it up). A shower of debris from exploding craft near you is definitely going to make noise. Etc. And spacecraft are often (at least with current tech) rather noisy places to be to begin with; sound isn't dampened well. So yes, "sound" doesn't travel through space effectively, but that doesn't mean space combat will be quiet.
There are, of course, additional complexities to using lasers in space -- no show stoppers, though. The Soviets experimented with a high power chemical laser system in space. The one of the many advantages of chemical lasers is that much of the waste heat (which all high powered lasers generate in droves -- think of how much heat you want to impart to your target, now multiply it by 3-10x for laser losses and more for losses during transit) is carried off in the exhaust; they're really kind of like rocket engines. But in that regard, they also provide thrust like a rocket engine. So you have to carefully and very precisely cancel out the thrust provided by the laser when it's in operation. The exhaust also gives away your position and it's chemical signature makes obvious what you're doing (the Soviets went to great lengths to disguise the fact that they were testing a laser).
Still, laser weapons in space are an obvious choice. No need for deuterium-fluoride lasers or anything of that nature, either, since atmospheric absorption isn't an issue. Even when it comes to missiles, due to the tremendous relative speeds involved, even missiles themselves would likely just be drones that carry lasers or other equivalent weaponry.
So if you're envisioning combat to be far enough away that the light speed delay poses a problem, exactly what weapon are you envisioning that *doesn't* have this problem? If light is too slow.... Plus, if you're that far away, you're not going to be closing in on each other worth a flip. You've got plenty of time for your system to make guesses about how the target is going to move; it'll nail them sooner or later. And if you think running that laser takes a lot of power/fuel/whatever, what do you think rapidly changing the trajectory of an entire spacecraft for days on end (enough to move it out of the path of a laser in under 0.6 seconds) will consume? The reality is that if you're far enough away that light is too slow, then your combat will just be conducted closer.
Sooner or later nuclear weapons or similar would become part of space combat. There's so much empty space, true high population space colonies are so far off, and it's easy enough to set "no nukes near planets" as a MAD boundary, it seems it's going to happen. Aka, even if not a conventional nuclear weapon, with the increasing energy density demands required by space propulsion, you'll at least end up with something similar. They impose interesting constraints on space combat, as they're very different from on the ground. Almost no pressure wave, but the radiation threat is dramatically greater (nothing absorbs it and harder to block it in space)
Combat would presumably be a "you're on your own" thing. Reinforcements would take *way* too long to arrive except perhaps right near a planet or base. Space is just really, really big and most of your time in space, you're drifting or providing a constant accel.
Since all combat seems to be heading this way anyway, one might as well just say: Drones. Due to the light speed delay, they'd have to be much more automated, but again, we're headed that way anyway. Carrying around a person and a life support system is a *huge* mass and complexity penalty.
So what sort of legal framework is there that gives the libertarian water-rights owner the right to sue the fracker? "Suing" is a legal construct, and requires "legal basis" for the suit to be brought. Aka, the fracker has violated some sort of law. So in this libertarian world, we have laws about water discharge chemical levels? I thought that was the sort of stuff that libertarians hated -- laws that say what they can't dump into the land, what they can't dump into the water, what they can't dump into the air, etc.
A general takeaway from the paper: food is environmentally devastating to produce.
Combine with: exercise takes calories (basic fact; the work doesn't come from nowhere, and no, being thinner and having a reduced idle metabolic rate doesn't come close to the amount burned during exercise)
Net result: Significantly increasing (~50% or more) your daily burned calories by walking or biking several hours per day to get to your destinations is environmentally devastating. 8x so if you're not vegan, since meat takes so much water and energy to produce per unit kcal.
"Greenest" practical mode of personal transportation: low cross-section streamlined -electric- (not pedal) powered bicycle.
It's a completely retarded idea in the first place. Why add a ton of complexity to what is a simple power circuit? How much more expensive and complicated do they need to make the chargers?
You're thinking way, way too small here. "Why add a ton of complexity to a simple doorknob?" Because the benefits outweigh the costs. And the benefits in terms of smart grid usage (greater grid reliability, greater generation capacity, greater efficiency, more renewables) and safety (no power flowing until there's a secure connection with a device that can tolerate the socket's frequency and voltage -- no more "put fork in a socket, get zapped" stuff, no more sparking loose connections) easily outweigh the extra cost, especially when you consider how small the cost will be when these sockets are churned out in Chinese factories by the billions. The cost of the socket hardware itself isn't even the main cost in installing a socket, not by a long shot. The addition of a 10-cent microchip-controlled switch (which is probably how much this will cost if the level of bulk you can get from mandating said sockets in the electrical code came to be) wouldn't even be noticed.
The US learned a frustrating lesson about this in the 1980s when they discovered that this was precisely how the Soviets were listening into our communications in our war games exercises.
Of course, we had a number of fun ways to listen in on them that they either didn't know about or kept forgetting about. Like how, for example, the radio signals on early mobile phones didn't just propagate laterally (which they were very careful about), but also up. And can be heard from really far up, if you have a good enough ear in orbit ;)
It was always fun, chatting with an old friend who served in military intelligence during the Cold War.
Um, it costs $60-90k. It *is* a car for rich people. Full stop.
Graphite does burn in some circumstances, and it's a myth that it does not.
* Fresh, pure graphite under atmospheric conditions with no additional source of heat will erode at high temperatures, but not self-sustain. Which is still quite bad.
* Any alteration to those starting conditions can yield a self-sustaining graphite fire. That is, A) alteration to the graphite structure due to long periods of intense radiation bombardment and/or infiltration, B) significant impurities or defects in the graphite during production, C) non-atmospheric conditions, such as high temperature steam instead of just air, or elevated pressures, D) continued input of nuclear decay heat, self-sustaining the erosion process as an effective continuous burn.
Your steel mill is a great example, as they're constantly burning through graphite electrodes (each lasts only about a week). To reiterate the significance of that: if that were nuclear core material, it'd all be in the air in a week.
When you think about it, this is the ultimate way for a rich person to use their money to flip the bird at other cars as they go by.
* My car is bigger than yours!
* My car is cooler than yours!
* My car is faster than yours!
* My car is greener than yours!
Etc, all at once. The other car might possibly best them in one category, but definitely not all. You just *know* there are plenty of rich people who would throw down money on something like that.