Modern naval ships are starting to use gas turbine engines (including the test ship for the US navy's railgun, I believe). Generators based on gas turbines can be up to 80% efficient at making electricity. But you're right, I believe the plan is to put the rail guns in nuclear powered cruisers.
Absolutely wrong. Upward acceleration is due launch energy. Downward acceleration is due to gravity and air resistance creates a terminal velocity that limits downward velocity. Fire a shot upwards with a rail gun and the project falls at the same speed as if it were dropped from a balloon. It does *not* come down at the same speed it went up at, it does *not* have the same kinetic energy.
You're wrong, except for extremely short range shots where you're better off using direct fire. A direct fire shot going 50 km through the lower atmosphere will slow down a lot more than an indirect shot going up into the upper atmosphere and coming back down. When you're shooting 100 km, or 1000 km, which is what the navy wants to do with it's rail guns, indirect fire is the only way to go.
Modern ICBMs follow indirect ballistic trajectories into space and impact at around 7 km/s. They certainly do not "fall at the same speed as if they were dropped from a balloon."
When conventional large guns want to vary their range they don't send out a guy with a teaspoon to add or remove a bit of gunpowder. They change their elevation. Ballistic shells follow parabolas determined by the quadratic equation. There are two solutions: the "direct" one, like firing a handheld gun, and the "indirect" one, where you shoot up and the shell comes back down.
Neglecting air resistance, a shell fired upwards will come down at the same speed it was fired. Including air resistance, any shot that goes more than a few tens of kilometres will be going faster when it hits if you use the indirect solution because the air is thinner up high. ICBMS are ballistic (that's what the B is) missiles that fly on suborbital trajectories out of the atmosphere, halfway around the planet, then come down at several kilometres per second. A large railgun could fire a shell that does the same thing.
Kinetic energy projectiles DO replace explosive warheads, except perhaps for special purpose munitions such as the delayed fuses used to penetrate deeply buried bunkers. Even then, a shaped kinetic projectile might well work better.
Muzzle velocity in a conventional gun is ultimately limited by the speed of the expansion of whatever explosive you're using. Modern military shells using high velocity explosives can get higher muzzle velocities, and you can play a variety of tricks to increase things still further, but it's hard to do much better than large artillery already does. You can get even higher muzzle velocities using compressed air (which is how the hypervelocity projectile test labs do it) but it requires a lot of infrastructure and still has muzzle velocity limitations.
Railguns are limited by how strong you can make a magnetic field and how fast you can move it, which is really, really fast. Conventional explosive guns simply can't compete with rail guns in terms of muzzle velocity. For a projectile of the same size (and beyond a certain size even that factor becomes less significant) muzzle velocity determines range. If you want to shoot beyond a few hundred kilometres you simply can't use explosives as propulsion.
That's one of the motivations behind developing rail guns. You can shoot down missiles. Hypersonic missiles would be harder, but still fairly easy to track on the way in, and possible to shoot down.
A hunk of metal going mach 10 on a ballistic trajectory, fired from a thousand kilometres away is much harder to shoot down. And since it's coming down on a suborbital trajectory it could go right through your carrier from top to bottom. Your picket ship would have to fly to be able to get in the way.
Ballistic equations are quadratic, and have two solutions. If the lower solution happens to intersect the ground, you use the higher one, firing the shell up and it hits the target on the way down. The higher elevation solution is usually better in naval gunnery anyway because then the shells tend to hit the tops of the ships, which are often harder to armour, and the exit holes are in the bottom. When the Bismarck was engaged in WWII the battle was at such close range that a lot of the shots went straight through, causing relatively little damage. If the shell has to go into space on it's way, that's actually good - less air resistance. ICBMs use suborbital trajectories of just like that.
Having said that, in modern naval warfare you don't really ever shoot anything big at such close range. Generally parts of your own task force will be over the horizon to ships at the centre. Railgun targets are likely to be hundreds, eventually thousands of kilometres away.
Why would you use a straight shot? Rail guns give higher velocity without requiring explosives. So you don't need to carry stuff that can blow up. In terms of shooting, a high power rail gun can shoot much farther than an explosive gun. Ultimately, if you had one powerful enough you could hit a target anywhere on the planet, including shooting yourself in the back. See "intercontinental ballistic missile" for examples of what ballistic weapons can do today with slightly different technology.
It's not entanglement. There's only one neutron. It sounds like a kind of quantum tunnelling, except across "universes." There are types of tunnelling where distance doesn't have the same effect you might expect, but there are other types where it does.
I imagine the people who seriously believe that aren't particularly nice people, but the idea itself is interesting as satirical counterpoint. Women make the majority of purchasing decisions in western countries (and possibly in non-western countries as well), which gives them a lot of influence over the economy. Advertisers know that, and outside of some niche areas tend to target women. Women also play a dominant role in childrearing and education, giving them majority influence on the next generation.
Clearly women don't exclusively run the world, but the idea that men do is equally simplistic.
"What's your gender? I ask in order to check my privlege, perhaps the contents of your underwear entitles your lame argument to more respect than I would otherwise award it?"
Nicely put. If you have to ask what someone's gender is in order to figure out how to talk (or listen) to them, then you're doing something wrong. Unfortunately the concept of "privilege" has been warped into a doctrine that seems very much to require that very thing.
Females generally (standard disclaimer for anyone dumb enough not to already know: group statistics say nothing about individuals) show more interest in communication, language and social tasks than physical, mechanical and solitary ones. Quite a bit of that may well be socialization, but similar patterns are also observed in other primates, so there may well be some real genetic sexual dimorphism.
Personally, I think that the type of jobs available in programming are bad for everybody, but are especially unattractive to women. Changing that is probably a worthwhile pursuit. It doesn't seem to be one that most of the "tech billionaires" and big companies are interested in: often poorly paid extreme workaholics are corporate dream employees.
I strongly disagree with trying to solve a perceived sexism problem with institutionalized sexism. If you want more women in a particular field, by all means look at improving teaching methods, community attitudes, development techniques and career options to be more appealing. Don't introduce blatant and extreme discrimination. That gets you a bunch of pissed off people who are discriminated against, a bunch of people who might have been happier in a different field who were discriminated in favour of, and a society that thinks sexual discrimination is okay.
A lot of GMO efforts are aimed at reducing the use of pesticides, especially ones we know are harmful. Others are to increase yields or allow things to be grown In areas that would otherwise not be suitable.
We may grow lots of food in North America but it's done at a high cost to the environment, and getting it to places where they don't grow lots of food has always been a problem.
I don't think it's an interferometer. It's a standard diffraction lens, just like the Canon one you linked, that produces a real image, not an interference pattern. You could stand at the focal point and see an image.
It would be an interferometer if you put a ring of telescopes on the rim instead of at the focus.
So long as you're not looking at something really close, the little bit of parallax you get by going around the planet isn't going to cause too many problems. And if you're looking at something where it does matter, you just take shorter exposures and stack them. As a bonus you get 3D measurements.
Action potentials are a bit funny. They're not actually movements of electrons down a wire like we're used to thinking about, but rather propagating waves of changes in the way cellular pumps move heavy ions through the cell membrane. Action potentials provide essentially no long-distance current, for example.
If you applied 15 mV across the SA node (the heart's built in pacemaker) at just the right time in the cardiac sequence you might be able to interfere enough to stop the organized contraction. There's a lab at my university that's been looking at analyzing chaotic heart contractions in order to use very small, very well-timed pacemaker signals, to correct them.
You would absolutely have to do it internally though ("applied directly to the heart"). The human body is basically a bag of salt water, which conducts quite well (about 300 Ohm from head to toe IIRC) surrounded by skin, which is a pretty good insulator. So if you want to electrocute someone, stab the electrodes in first.
You missed his point. 1 nA per ring, second, hour, whatever, makes no sense. An amp is already of measurement of charge per unit time. If the current measurement is correct, which I believe it is, then the GP's formula is correct. Multiplying a current (charge / unit time) by a time gives you a measure of total charge. Multiplying by the voltage then gives you total energy.
The previous posters are correct - the clear, low humidity air over deserts is more transparent to infrared light and radiative loss is the major reason for fast cooling at night. I've spent the night out in the Sahara. When the air cools off and you dig into the sand you realize that not only is the sand a decent insulator, just below the surface it's also much warmer than the air.
Dry batteries don't work well in the cold because chemical reactions slow down the colder it gets. Wet batteries don't *survive* the cold because things freeze. I say this both as someone whose camera batteries often needed to be hand warmed, and as someone who's had to change a car battery at -40 because it discharged, froze and cracked it's case.
You probably could stop someone's heart with 15 mV. But it would have to be applied directly to the heart, and at just the right time.
For external application (i.e. without the open heart surgery) it's going to take rather more than that. You generally need a current of around 100 mA through the heart to stop it. If you're not standing in a puddle of salt water or gripping a water pipe, it's going to take quite a bit more voltage to achieve that.
110 V household current can kill, if you manage to get a good connection hand to hand. I think the lowest voltages observed to kill someone were around 40 V, but that requires some fairly exceptional circumstances.
Airline pilots are rather better trained than the average driver. Things also tend to happen more slowly in the air. If you're ever in a collision situation that requires action as quick as you're probably used to on a daily basis in your car, you've screwed up royally.
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Perhaps that's why he said "game theory tells us."
Modern naval ships are starting to use gas turbine engines (including the test ship for the US navy's railgun, I believe). Generators based on gas turbines can be up to 80% efficient at making electricity. But you're right, I believe the plan is to put the rail guns in nuclear powered cruisers.
Maybe he wants to raise Isoroku Yamamoto. Except in that case he'd want a shovel, and a witch who specializes in reanimating ashes.
You're wrong, except for extremely short range shots where you're better off using direct fire. A direct fire shot going 50 km through the lower atmosphere will slow down a lot more than an indirect shot going up into the upper atmosphere and coming back down. When you're shooting 100 km, or 1000 km, which is what the navy wants to do with it's rail guns, indirect fire is the only way to go.
Modern ICBMs follow indirect ballistic trajectories into space and impact at around 7 km/s. They certainly do not "fall at the same speed as if they were dropped from a balloon."
When conventional large guns want to vary their range they don't send out a guy with a teaspoon to add or remove a bit of gunpowder. They change their elevation. Ballistic shells follow parabolas determined by the quadratic equation. There are two solutions: the "direct" one, like firing a handheld gun, and the "indirect" one, where you shoot up and the shell comes back down.
Neglecting air resistance, a shell fired upwards will come down at the same speed it was fired. Including air resistance, any shot that goes more than a few tens of kilometres will be going faster when it hits if you use the indirect solution because the air is thinner up high. ICBMS are ballistic (that's what the B is) missiles that fly on suborbital trajectories out of the atmosphere, halfway around the planet, then come down at several kilometres per second. A large railgun could fire a shell that does the same thing.
Kinetic energy projectiles DO replace explosive warheads, except perhaps for special purpose munitions such as the delayed fuses used to penetrate deeply buried bunkers. Even then, a shaped kinetic projectile might well work better.
Muzzle velocity in a conventional gun is ultimately limited by the speed of the expansion of whatever explosive you're using. Modern military shells using high velocity explosives can get higher muzzle velocities, and you can play a variety of tricks to increase things still further, but it's hard to do much better than large artillery already does. You can get even higher muzzle velocities using compressed air (which is how the hypervelocity projectile test labs do it) but it requires a lot of infrastructure and still has muzzle velocity limitations.
Railguns are limited by how strong you can make a magnetic field and how fast you can move it, which is really, really fast. Conventional explosive guns simply can't compete with rail guns in terms of muzzle velocity. For a projectile of the same size (and beyond a certain size even that factor becomes less significant) muzzle velocity determines range. If you want to shoot beyond a few hundred kilometres you simply can't use explosives as propulsion.
That's one of the motivations behind developing rail guns. You can shoot down missiles. Hypersonic missiles would be harder, but still fairly easy to track on the way in, and possible to shoot down.
A hunk of metal going mach 10 on a ballistic trajectory, fired from a thousand kilometres away is much harder to shoot down. And since it's coming down on a suborbital trajectory it could go right through your carrier from top to bottom. Your picket ship would have to fly to be able to get in the way.
Railgun projectiles would be guided, just like modern artillery shells.
Ballistic equations are quadratic, and have two solutions. If the lower solution happens to intersect the ground, you use the higher one, firing the shell up and it hits the target on the way down. The higher elevation solution is usually better in naval gunnery anyway because then the shells tend to hit the tops of the ships, which are often harder to armour, and the exit holes are in the bottom. When the Bismarck was engaged in WWII the battle was at such close range that a lot of the shots went straight through, causing relatively little damage. If the shell has to go into space on it's way, that's actually good - less air resistance. ICBMs use suborbital trajectories of just like that.
Having said that, in modern naval warfare you don't really ever shoot anything big at such close range. Generally parts of your own task force will be over the horizon to ships at the centre. Railgun targets are likely to be hundreds, eventually thousands of kilometres away.
Why would you use a straight shot? Rail guns give higher velocity without requiring explosives. So you don't need to carry stuff that can blow up. In terms of shooting, a high power rail gun can shoot much farther than an explosive gun. Ultimately, if you had one powerful enough you could hit a target anywhere on the planet, including shooting yourself in the back. See "intercontinental ballistic missile" for examples of what ballistic weapons can do today with slightly different technology.
Yeah, but most of them can spell "holes" properly.
Oh yeah, and math.
It's not entanglement. There's only one neutron. It sounds like a kind of quantum tunnelling, except across "universes." There are types of tunnelling where distance doesn't have the same effect you might expect, but there are other types where it does.
I imagine the people who seriously believe that aren't particularly nice people, but the idea itself is interesting as satirical counterpoint. Women make the majority of purchasing decisions in western countries (and possibly in non-western countries as well), which gives them a lot of influence over the economy. Advertisers know that, and outside of some niche areas tend to target women. Women also play a dominant role in childrearing and education, giving them majority influence on the next generation.
Clearly women don't exclusively run the world, but the idea that men do is equally simplistic.
"What's your gender? I ask in order to check my privlege, perhaps the contents of your underwear entitles your lame argument to more respect than I would otherwise award it?"
Nicely put. If you have to ask what someone's gender is in order to figure out how to talk (or listen) to them, then you're doing something wrong. Unfortunately the concept of "privilege" has been warped into a doctrine that seems very much to require that very thing.
Females generally (standard disclaimer for anyone dumb enough not to already know: group statistics say nothing about individuals) show more interest in communication, language and social tasks than physical, mechanical and solitary ones. Quite a bit of that may well be socialization, but similar patterns are also observed in other primates, so there may well be some real genetic sexual dimorphism.
Personally, I think that the type of jobs available in programming are bad for everybody, but are especially unattractive to women. Changing that is probably a worthwhile pursuit. It doesn't seem to be one that most of the "tech billionaires" and big companies are interested in: often poorly paid extreme workaholics are corporate dream employees.
I strongly disagree with trying to solve a perceived sexism problem with institutionalized sexism. If you want more women in a particular field, by all means look at improving teaching methods, community attitudes, development techniques and career options to be more appealing. Don't introduce blatant and extreme discrimination. That gets you a bunch of pissed off people who are discriminated against, a bunch of people who might have been happier in a different field who were discriminated in favour of, and a society that thinks sexual discrimination is okay.
A lot of GMO efforts are aimed at reducing the use of pesticides, especially ones we know are harmful. Others are to increase yields or allow things to be grown In areas that would otherwise not be suitable.
We may grow lots of food in North America but it's done at a high cost to the environment, and getting it to places where they don't grow lots of food has always been a problem.
I don't think it's an interferometer. It's a standard diffraction lens, just like the Canon one you linked, that produces a real image, not an interference pattern. You could stand at the focal point and see an image.
It would be an interferometer if you put a ring of telescopes on the rim instead of at the focus.
So long as you're not looking at something really close, the little bit of parallax you get by going around the planet isn't going to cause too many problems. And if you're looking at something where it does matter, you just take shorter exposures and stack them. As a bonus you get 3D measurements.
Action potentials are a bit funny. They're not actually movements of electrons down a wire like we're used to thinking about, but rather propagating waves of changes in the way cellular pumps move heavy ions through the cell membrane. Action potentials provide essentially no long-distance current, for example.
If you applied 15 mV across the SA node (the heart's built in pacemaker) at just the right time in the cardiac sequence you might be able to interfere enough to stop the organized contraction. There's a lab at my university that's been looking at analyzing chaotic heart contractions in order to use very small, very well-timed pacemaker signals, to correct them.
You would absolutely have to do it internally though ("applied directly to the heart"). The human body is basically a bag of salt water, which conducts quite well (about 300 Ohm from head to toe IIRC) surrounded by skin, which is a pretty good insulator. So if you want to electrocute someone, stab the electrodes in first.
You missed his point. 1 nA per ring, second, hour, whatever, makes no sense. An amp is already of measurement of charge per unit time. If the current measurement is correct, which I believe it is, then the GP's formula is correct. Multiplying a current (charge / unit time) by a time gives you a measure of total charge. Multiplying by the voltage then gives you total energy.
The previous posters are correct - the clear, low humidity air over deserts is more transparent to infrared light and radiative loss is the major reason for fast cooling at night. I've spent the night out in the Sahara. When the air cools off and you dig into the sand you realize that not only is the sand a decent insulator, just below the surface it's also much warmer than the air.
Dry batteries don't work well in the cold because chemical reactions slow down the colder it gets. Wet batteries don't *survive* the cold because things freeze. I say this both as someone whose camera batteries often needed to be hand warmed, and as someone who's had to change a car battery at -40 because it discharged, froze and cracked it's case.
You probably could stop someone's heart with 15 mV. But it would have to be applied directly to the heart, and at just the right time.
For external application (i.e. without the open heart surgery) it's going to take rather more than that. You generally need a current of around 100 mA through the heart to stop it. If you're not standing in a puddle of salt water or gripping a water pipe, it's going to take quite a bit more voltage to achieve that.
110 V household current can kill, if you manage to get a good connection hand to hand. I think the lowest voltages observed to kill someone were around 40 V, but that requires some fairly exceptional circumstances.
I'm pretty sure pre-emptive braking systems are designed to use the ABS system, not lock the brakes. So go ahead and swerve with controlled braking.
Airline pilots are rather better trained than the average driver. Things also tend to happen more slowly in the air. If you're ever in a collision situation that requires action as quick as you're probably used to on a daily basis in your car, you've screwed up royally.