Again, IIRC (not a given!), the extraterrestrial materials launchers were magnetic launchers, not railguns. Not that it's important for the rest of your comment, which I think is completely correct, but railguns have rapidly wearing parts (plasma on the rails) while magnetic launchers AFAIK have no wearout mechanism, there being for some designs no contact between the launched thing and the launcher structure.
I especially like the drill bits in copper. I'd use aluminum, as I think the mp of copper (1083C) would certainly soften steel bits and would probably mess up the cobalt bonding of tungsten carbide tooling. But that's only a detail - it's a good idea for getting robust stuff that doesn't pack densely to space with good volumetric efficiency (as measured by the value of the payload per cubic whatever).
has happened, with terrible results. Different machines of course, but nevertheless a demonstration that shit happens. There's no reason to believe that airport backscatter systems' software is any more reliable than that deployed on systems that have failed disastrously in the past.
as a payload, and probably other bulk materials that would be valuable for space-based activities. You can imagine liquid oxygen (good for a propellant and breathing), UDMH and N2O4 (storable propellants), and other stuff.
The projectile will get very hot, but not for long. A design with a thin ablative skin and an underlying layer of thermal insulation would probably make it through the atmosphere.
There are many studies of rail gun/magnetic launch/etc. systems for putting bulk materials in space. Atmospheric drag is a big term in the energy budget, and IIRC, there could be significant advantages to getting above some of the atmosphere by launching from high elevations.
acceleration. IIRC, the projectile reached Mach 8, about 2700 m/sec. It's an unpowered projectile, so it got all its velocity in the railgun, which I'm going to estimate as about 100 feet long. Call it 30 meters long. Let's say that its velocity increase during the firing was linear with its change in position in the gun, so we can approximate its average velocity in the gun as 2700/2 = 1350 m/sec. This gives us a time in the gun of about 30/1350 = 0.022 seconds. Since V (muzzle velocity) = a (acceleration) * t (time during which velocity is changing), we can figure out what acceleration that puppy had to endure to go from zero to Mach 8 in 22 milliseconds.
Ta da: (1350m/sec)/0.022 sec = 61,363m/sec^2. Since Earth's gravity is (IIRD) 9.8m/sec^2, we're looking at over 6 thousand Gees.
Clearly, no wetware is gonna make it through alive. Ditto for normal fabricated parts & stuff. Lots of electronics and explosives will handle it (cannon shells, for example), but there we are, squarely in military applications.
There really aren't any civilian applications for this. It does present some fascinating problems in science (plasma & hydrodynamics) and engineering (BIG pulsed HV supplies, keeping things together in the face of incredible Lorentz forces, etc.), and it may keep civilian scientists and engineers imployed, but really - it's a military technology.
is the bond energy and fracture mechanics. For example, ceramic armor breaks into lots of very small particles when hit by a projectile: each fracture surface is created using energy from the incoming projectile, and hence dissipates the projectile's energy. Ceramics aren't very dense compared to tungsten or DU, but their fracture energies are very high. Density counts for projectiles because it's one of the parameters that determines the pressure at the impact point, which in turn is one of the parameters that predicts penetration efficacy. Tungsten is a little more dense than DU, not significantly so for projectile use. A DU projectile will catch fire when it penetrates armor, contributing to its destructive effects. Tungsten doesn't do this. DU is a low-level radiological hazard, tungsten isn't, so for cleaning up after a battle, tungsten is a better choice. DU may have some low-level chemical toxicity, but there's evidence that tungsten (when imbedded as particles under skin) is toxic as well. I speculate the choice of D vs W for projectiles is mainly economic (unless you need to incinerate the occupants of that tank you're killing), as I think DU is cheaper than W.
I think the circumstance you posit, being a matter of individual personal opinion unconnected to governmental business, is not applicable to the Wikileaks release. Better if you support your opinion with argument based on relevant data.
I disagree with your assumption that the threat of publication will necessarily cause intragovernmental communications to be less than candid. And even if that were true, it is something that needs to be changed. Employees of our government need to be trained and rewarded to provide accurate information without regard to whether their communications may be disclosed.
Secrecy provides a haven for incompetence and evil. I'd rather we deal with the inconvenience and hassle of transparency. I think the long term result will be a better world than we have now.
Much like Decatur's "My country, right or wrong", which most blindly quote without the rest of the idea, later articulated by Sen. Carl Schurz: “My country, right or wrong; if right, to be kept right; and if wrong, to be set right.”
This seems a bit like saying that because a computer is just a really fast abacus, there's really no difference between them or their effects.
At some point, mere quantitative increase becomes a qualitative difference.
If it now takes 2 seconds to do with Facebook's new tool what used to take 2 days, that's a qualitative difference (degradation of privacy) that people might reasonably be concerned about.
Yes, the law requires three things: Offer, Acceptance, and Consideration. Any of these three missing - no contract.
Not sure what would be a "good reason", but
on
The Hackintosh Guide
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· Score: 1
I've used Macs since 1984. In my first startup, we had three IBM PCs, and my memory of using them was that I had user's manuals for everything in my lap, always. One day, our three PCs all croaked simultaneously for apparently different reasons, and my friend brought in his then-new Mac Classic. Two days later, we gave the PCs to a local high school and bought Macs. My memory of that transition is that I lost track of the user's manuals by the second day we had the Macs.
Since then I've used Macs whenever I had a choice. Not because they're the fastest, or most flexible, or the cheapest, or the best for somebody who wants to dig into the guts of the soft/hardware and make it do stuff, but because they acted more like a tool than a project and helped me do my work. I've checked in as various versions of Windows have come and gone, but the Mac has remained a better choice for me.
I've had my frustrations with Macs, and I'm not one of the fanbois who thinks Jobs and co. can do no wrong. But, gotta say, I still am utterly unconcerned with what antivirus apps I ought to have on my machine, pretty much everything I have wanted to plug into my Macs over the years has Just Worked as I wanted. The service I've gotten from Apple has been exceptional. I took a failing G4 MacBook in for its 3th service, two days before my AppleCare policy expired, and the Apple guy at the Genius Bar gave me (that's GAVE me) a new Intel MacBook without my having said more than "Hi, I'm back.". That's a level of customer service I value and that seems uncommon in the PC world.
As well, having a Mac frees me (almost) from Microsoft, which I've found to be a Good Thing over the years. I am troubled by Apple's continued construction of its walled garden, and I'm concerned it's another Microsoft in the making. But for now, their systems work better for me than the systems on the PC or *nix side.
you're *presumed* to know the law. This how the law holds people responsible for violations of law despite the impossibility of actually knowing the law, which as noted by earlier posters, is simply no longer possible.
It is actually (nearly) invisible, and it's not "a light-yellow flame". I have a hydrogen generator, puts out 99.9995% pure H2. I have ignited the outlet stream to test a UV detector (hydrogen flame in air is UV-rich), and it's a faint, bluish flame. Quite hard to see in normal room lighting, clearly visible when the environment is dark. In sunlight, you wouldn't have a prayer of seeing a hydrogen flame from a leaky pipe fitting. If the flame looks yellow, it's because of dust, probably carrying sodium compounds. Sodium compounds have strong yellow emission lines in flame and plasma spectra.
This conduct could easily support a tort claim for intentional infliction of emotional distress. If proved, the verdict might be used as res judicata against the recording party in a subsequent trial on the recording.
Umm, true for a collision where everything holds together, but nearly all of the impactor kinetic energy would be converted to heat. This, in turn, would vaporize vast quantities of rock (wish I had time to do the energy vs. specific heat calcs) which would blow the planet apart. I guess momentum conservation would impart up to 3 m/s to the center of mass of the exploding ensemble, and I don't think we'd notice. But thanks, I hadn't thought about the momentum exchange issues.
Well, let's see. Suppose we decide to accelerate an asteroid 100km in diameter using whatever long-term propulsion we can (nuke-powered VASIMIR, big solar sails, whatever) and use the well-known gravity assist that the planets can provide. If the asteroid has an average density of 4 g/cc, how fast would we have to get it going when it impacted earth to give enough energy to blow the planet apart?
Blow the planet apart = move all of its mass to escape velocity. Earth escape velocity is about 11.2 km/sec. 1kg moving at 11.2 km/sec has about 6.27e7 Joules of kinetic energy. Earth's mass is about 5.97e24 kg. (No, I didn't weigh it, but Google is my friend). So, to move all of the earth's mass away at a speed of 11.2 Km/sec would require (6.27e7 J/kg)*(5.97e24kg) = 3.75e32 Joules.
OK, this doesn't count the energy needed to break the rock up, but cut me some slack, this exercise is tuned to the accuracy standards of physicists, i.e., we're happy if we get it within a few orders of magnitude.
Back to our 100Km diameter billiard ball. It's mass is about 2.09e18kg. So, to get about 10^32 Joules of kinetic energy on target, it will have to be moving at about 10,000,000 m/sec. This is about 3% the speed of light.
This is surely overkill in that it's the energy needed to push all the earth's mass to escape velocity. Probably less than 1% of this energy would suffice to crack the planet into pieces. Would this count as blowing the earth up?
"It's a good thing, overall. Yes, there are some innocent folks getting detained, deported, and denied entry, but in time those will work out."
No. This contravenes American principles. For example, we decided it was worth presuming innocence, thereby guaranteeing freedom for some portion of the guilty, rather than punishing the innocent. We pay the cost of this freedom, and IMHO, we're the better for it. I'd rather distribute the cost of doing it this way over our entire society than concentrate it on "some innocent folks" falsely detained/deported/convicted/tortured in black facilities/etc. "Some innocent folks" - nicely dismissive of people who deserve better. But, hey - feels ok not to think about them if they're just "some innocent folks" out there. Not like it's anyone you know or care about or depend on.
"America as a nation is only 234 years old, compared to other nations that have been in roughly the same state for a thousand years. We are cocky and immature, and so is our intelligence system."
Your assumption that things get better as cultures age is unfounded. As but one example, China and Egypt are two cultures having roots far, far deeper in the past than America - by your prognostication, they should have grown "up just fine" by now. I'm curious - in which culture, American, Chinese, or Egyptian, would you rather be an accused criminal/terrorist?
" Give it time to grow, but make sure it's kept in check by the public activists and watchdogs."
In my view, the public activists and watchdogs are being outcompeted by the growing power of the state. This is linked to financial interests, which have almost completely taken over American legislative, judicial, and executive governmental functions. Public activists and watchdogs may march and bark, but they less and less influence events.
Your worldview simply kicks the can down the road, as our problems worsen. Time fixes nothing. Courageous people who won't rationalize, ignore, or excuse injustice make our lives better. If you believe what you wrote, you're not in that crowd.
Yes, I do. So what's your point? We should continue the madness that has gone before us? How about we find the collective stones to do something different, to make the sacrifices and behavioral changes from the individual to the national level that we must if we or our kids are ever to have a world in which there's progress in aspects of life that don't have to do with technology?
Um...if "the courts maintain the fiction that it is", well, that "fiction" is (legal) reality. In the absence of subsequent action by Congress, that is.
Looked at the drone shootdown video. A considerable dwell time (seconds) was required between the first beam impingement and the first apparent indication of damage. During this time, the drone was flying straight and level, no maneuvering.
This isn't a realistic test, IMHO. In a combat environment, with laser fire being an anticipated threat, there will be sensors aboard the target that will note impinging energy and either tell the pilot to jink or will execute an autonomous jink routine that will prevent the laser from getting a long enough dwell time to damage the target.
As I understand it, this tech is CW, which means the beam really does have to sit on an aim point for a considerable time (in a combat event perspective) to do damage. Against a maneuvering target, it's not going to do much good. Two ways forward include brute force power scaleup (to first order will reduce the required dwell time in proportion to the power scaleup ratio) or go to pulsed mode, in which extremely high pulse power triggers nonlinear absorption of energy in the target material.
For now, this is a demo of superb optical tracking of a nonmaneuvering target and slaving a scaled up laser pointer to the tracker. Real (i.e., intelligent) enemies won't be so easy to splash.
Has there been any commentary or explanation from SpaceX about the increasing roll rate that showed in the on-board video towards the end of that video? I've looked, haven't found any. Just curious.
Slashdot Mirror
Again, IIRC (not a given!), the extraterrestrial materials launchers were magnetic launchers, not railguns. Not that it's important for the rest of your comment, which I think is completely correct, but railguns have rapidly wearing parts (plasma on the rails) while magnetic launchers AFAIK have no wearout mechanism, there being for some designs no contact between the launched thing and the launcher structure.
I especially like the drill bits in copper. I'd use aluminum, as I think the mp of copper (1083C) would certainly soften steel bits and would probably mess up the cobalt bonding of tungsten carbide tooling. But that's only a detail - it's a good idea for getting robust stuff that doesn't pack densely to space with good volumetric efficiency (as measured by the value of the payload per cubic whatever).
has happened, with terrible results. Different machines of course, but nevertheless a demonstration that shit happens. There's no reason to believe that airport backscatter systems' software is any more reliable than that deployed on systems that have failed disastrously in the past.
See http://courses.cs.vt.edu/cs3604/lib/Therac_25/Therac_1.html
for one example.
as a payload, and probably other bulk materials that would be valuable for space-based activities. You can imagine liquid oxygen (good for a propellant and breathing), UDMH and N2O4 (storable propellants), and other stuff.
The projectile will get very hot, but not for long. A design with a thin ablative skin and an underlying layer of thermal insulation would probably make it through the atmosphere.
There are many studies of rail gun/magnetic launch/etc. systems for putting bulk materials in space. Atmospheric drag is a big term in the energy budget, and IIRC, there could be significant advantages to getting above some of the atmosphere by launching from high elevations.
acceleration. IIRC, the projectile reached Mach 8, about 2700 m/sec. It's an unpowered projectile, so it got all its velocity in the railgun, which I'm going to estimate as about 100 feet long. Call it 30 meters long. Let's say that its velocity increase during the firing was linear with its change in position in the gun, so we can approximate its average velocity in the gun as 2700/2 = 1350 m/sec. This gives us a time in the gun of about 30/1350 = 0.022 seconds. Since V (muzzle velocity) = a (acceleration) * t (time during which velocity is changing), we can figure out what acceleration that puppy had to endure to go from zero to Mach 8 in 22 milliseconds.
Ta da: (1350m/sec)/0.022 sec = 61,363m/sec^2. Since Earth's gravity is (IIRD) 9.8m/sec^2, we're looking at over 6 thousand Gees.
Clearly, no wetware is gonna make it through alive. Ditto for normal fabricated parts & stuff. Lots of electronics and explosives will handle it (cannon shells, for example), but there we are, squarely in military applications.
There really aren't any civilian applications for this. It does present some fascinating problems in science (plasma & hydrodynamics) and engineering (BIG pulsed HV supplies, keeping things together in the face of incredible Lorentz forces, etc.), and it may keep civilian scientists and engineers imployed, but really - it's a military technology.
is the bond energy and fracture mechanics. For example, ceramic armor breaks into lots of very small particles when hit by a projectile: each fracture surface is created using energy from the incoming projectile, and hence dissipates the projectile's energy. Ceramics aren't very dense compared to tungsten or DU, but their fracture energies are very high. Density counts for projectiles because it's one of the parameters that determines the pressure at the impact point, which in turn is one of the parameters that predicts penetration efficacy. Tungsten is a little more dense than DU, not significantly so for projectile use. A DU projectile will catch fire when it penetrates armor, contributing to its destructive effects. Tungsten doesn't do this. DU is a low-level radiological hazard, tungsten isn't, so for cleaning up after a battle, tungsten is a better choice. DU may have some low-level chemical toxicity, but there's evidence that tungsten (when imbedded as particles under skin) is toxic as well. I speculate the choice of D vs W for projectiles is mainly economic (unless you need to incinerate the occupants of that tank you're killing), as I think DU is cheaper than W.
I think the circumstance you posit, being a matter of individual personal opinion unconnected to governmental business, is not applicable to the Wikileaks release. Better if you support your opinion with argument based on relevant data.
I disagree with your assumption that the threat of publication will necessarily cause intragovernmental communications to be less than candid. And even if that were true, it is something that needs to be changed. Employees of our government need to be trained and rewarded to provide accurate information without regard to whether their communications may be disclosed.
Secrecy provides a haven for incompetence and evil. I'd rather we deal with the inconvenience and hassle of transparency. I think the long term result will be a better world than we have now.
My money is on Scrith.
I love that this electrifying study was published in *Current Biology*.
Much like Decatur's "My country, right or wrong", which most blindly quote without the rest of the idea, later articulated by Sen. Carl Schurz: “My country, right or wrong; if right, to be kept right; and if wrong, to be set right.”
http://en.wiktionary.org/wiki/my_country,_right_or_wrong
This seems a bit like saying that because a computer is just a really fast abacus, there's really no difference between them or their effects.
At some point, mere quantitative increase becomes a qualitative difference.
If it now takes 2 seconds to do with Facebook's new tool what used to take 2 days, that's a qualitative difference (degradation of privacy) that people might reasonably be concerned about.
Yes, the law requires three things: Offer, Acceptance, and Consideration. Any of these three missing - no contract.
I've used Macs since 1984. In my first startup, we had three IBM PCs, and my memory of using them was that I had user's manuals for everything in my lap, always. One day, our three PCs all croaked simultaneously for apparently different reasons, and my friend brought in his then-new Mac Classic. Two days later, we gave the PCs to a local high school and bought Macs. My memory of that transition is that I lost track of the user's manuals by the second day we had the Macs.
Since then I've used Macs whenever I had a choice. Not because they're the fastest, or most flexible, or the cheapest, or the best for somebody who wants to dig into the guts of the soft/hardware and make it do stuff, but because they acted more like a tool than a project and helped me do my work. I've checked in as various versions of Windows have come and gone, but the Mac has remained a better choice for me.
I've had my frustrations with Macs, and I'm not one of the fanbois who thinks Jobs and co. can do no wrong. But, gotta say, I still am utterly unconcerned with what antivirus apps I ought to have on my machine, pretty much everything I have wanted to plug into my Macs over the years has Just Worked as I wanted. The service I've gotten from Apple has been exceptional. I took a failing G4 MacBook in for its 3th service, two days before my AppleCare policy expired, and the Apple guy at the Genius Bar gave me (that's GAVE me) a new Intel MacBook without my having said more than "Hi, I'm back.". That's a level of customer service I value and that seems uncommon in the PC world.
As well, having a Mac frees me (almost) from Microsoft, which I've found to be a Good Thing over the years. I am troubled by Apple's continued construction of its walled garden, and I'm concerned it's another Microsoft in the making. But for now, their systems work better for me than the systems on the PC or *nix side.
YMMV, as always.
you're *presumed* to know the law. This how the law holds people responsible for violations of law despite the impossibility of actually knowing the law, which as noted by earlier posters, is simply no longer possible.
That would be Admiral john Poindexter.
http://en.wikipedia.org/wiki/Information_Awareness_Office
It is actually (nearly) invisible, and it's not "a light-yellow flame". I have a hydrogen generator, puts out 99.9995% pure H2. I have ignited the outlet stream to test a UV detector (hydrogen flame in air is UV-rich), and it's a faint, bluish flame. Quite hard to see in normal room lighting, clearly visible when the environment is dark. In sunlight, you wouldn't have a prayer of seeing a hydrogen flame from a leaky pipe fitting. If the flame looks yellow, it's because of dust, probably carrying sodium compounds. Sodium compounds have strong yellow emission lines in flame and plasma spectra.
This conduct could easily support a tort claim for intentional infliction of emotional distress. If proved, the verdict might be used as res judicata against the recording party in a subsequent trial on the recording.
Umm, true for a collision where everything holds together, but nearly all of the impactor kinetic energy would be converted to heat. This, in turn, would vaporize vast quantities of rock (wish I had time to do the energy vs. specific heat calcs) which would blow the planet apart. I guess momentum conservation would impart up to 3 m/s to the center of mass of the exploding ensemble, and I don't think we'd notice. But thanks, I hadn't thought about the momentum exchange issues.
Well, let's see. Suppose we decide to accelerate an asteroid 100km in diameter using whatever long-term propulsion we can (nuke-powered VASIMIR, big solar sails, whatever) and use the well-known gravity assist that the planets can provide. If the asteroid has an average density of 4 g/cc, how fast would we have to get it going when it impacted earth to give enough energy to blow the planet apart?
Blow the planet apart = move all of its mass to escape velocity. Earth escape velocity is about 11.2 km/sec. 1kg moving at 11.2 km/sec has about 6.27e7 Joules of kinetic energy. Earth's mass is about 5.97e24 kg. (No, I didn't weigh it, but Google is my friend). So, to move all of the earth's mass away at a speed of 11.2 Km/sec would require (6.27e7 J/kg)*(5.97e24kg) = 3.75e32 Joules.
OK, this doesn't count the energy needed to break the rock up, but cut me some slack, this exercise is tuned to the accuracy standards of physicists, i.e., we're happy if we get it within a few orders of magnitude.
Back to our 100Km diameter billiard ball. It's mass is about 2.09e18kg. So, to get about 10^32 Joules of kinetic energy on target, it will have to be moving at about 10,000,000 m/sec. This is about 3% the speed of light.
This is surely overkill in that it's the energy needed to push all the earth's mass to escape velocity. Probably less than 1% of this energy would suffice to crack the planet into pieces. Would this count as blowing the earth up?
"It's a good thing, overall. Yes, there are some innocent folks getting detained, deported, and denied entry, but in time those will work out."
No. This contravenes American principles. For example, we decided it was worth presuming innocence, thereby guaranteeing freedom for some portion of the guilty, rather than punishing the innocent. We pay the cost of this freedom, and IMHO, we're the better for it. I'd rather distribute the cost of doing it this way over our entire society than concentrate it on "some innocent folks" falsely detained/deported/convicted/tortured in black facilities/etc. "Some innocent folks" - nicely dismissive of people who deserve better. But, hey - feels ok not to think about them if they're just "some innocent folks" out there. Not like it's anyone you know or care about or depend on.
"America as a nation is only 234 years old, compared to other nations that have been in roughly the same state for a thousand years. We are cocky and immature, and so is our intelligence system."
Your assumption that things get better as cultures age is unfounded. As but one example, China and Egypt are two cultures having roots far, far deeper in the past than America - by your prognostication, they should have grown "up just fine" by now. I'm curious - in which culture, American, Chinese, or Egyptian, would you rather be an accused criminal/terrorist?
" Give it time to grow, but make sure it's kept in check by the public activists and watchdogs."
In my view, the public activists and watchdogs are being outcompeted by the growing power of the state. This is linked to financial interests, which have almost completely taken over American legislative, judicial, and executive governmental functions. Public activists and watchdogs may march and bark, but they less and less influence events.
Your worldview simply kicks the can down the road, as our problems worsen. Time fixes nothing. Courageous people who won't rationalize, ignore, or excuse injustice make our lives better. If you believe what you wrote, you're not in that crowd.
Yes, I do. So what's your point? We should continue the madness that has gone before us? How about we find the collective stones to do something different, to make the sacrifices and behavioral changes from the individual to the national level that we must if we or our kids are ever to have a world in which there's progress in aspects of life that don't have to do with technology?
Um...if "the courts maintain the fiction that it is", well, that "fiction" is (legal) reality. In the absence of subsequent action by Congress, that is.
Looked at the drone shootdown video. A considerable dwell time (seconds) was required between the first beam impingement and the first apparent indication of damage. During this time, the drone was flying straight and level, no maneuvering. This isn't a realistic test, IMHO. In a combat environment, with laser fire being an anticipated threat, there will be sensors aboard the target that will note impinging energy and either tell the pilot to jink or will execute an autonomous jink routine that will prevent the laser from getting a long enough dwell time to damage the target. As I understand it, this tech is CW, which means the beam really does have to sit on an aim point for a considerable time (in a combat event perspective) to do damage. Against a maneuvering target, it's not going to do much good. Two ways forward include brute force power scaleup (to first order will reduce the required dwell time in proportion to the power scaleup ratio) or go to pulsed mode, in which extremely high pulse power triggers nonlinear absorption of energy in the target material. For now, this is a demo of superb optical tracking of a nonmaneuvering target and slaving a scaled up laser pointer to the tracker. Real (i.e., intelligent) enemies won't be so easy to splash.
Don't know how I missed it. It was even more than one sentence in TFA. Mea culpa or chupa capybara, or something....
Has there been any commentary or explanation from SpaceX about the increasing roll rate that showed in the on-board video towards the end of that video? I've looked, haven't found any. Just curious.