I've yet to speak with someone with a three digit IQ over there.
Not a big surprize since half of all people have IQ < 100, since the tests are designed to have a mean of 100. (Assuming mean and median are about the same, which is reasonable in this case).
I stand by my word. But this algorithm you link to cannot factor a prime number. Nobody can factor a prime number. I posted that because the original poster referred to factoring a prime number and I was just making the point that RSA actually uses composite numbers that are a multiple of two large prime numbers. And the only way you can factor a prime N is N*1, but this doesn't count.
Pu-242 is not fissile because it has an even number of nucleons. Therefore it cannot be used for a bomb. Bombs use Pu-239 as I said already, or Pu-241 (but I'm not sure about that one). FYI, here is a list of the common fissile niclei:
U-233, U-235, Pu-239, Pu-241
Hmmm, don't you mean converting U-238 to Pu-239 using U-235 burning breeder reactors? Anyway, RTG's use either Plutonium carbide or dioxide, which are more or less ceramic compounds, and are made into large pellets when used as RTGs. These pellets will not break into dust on reentry. There have been cases of satellites using these crashing down with the RTG box recovered almost intact. Of course there are cases of satellites using older type RTGs (like SNAP-9) that have broken up and contaminated some area, but the level of radiation was not much above the average, i.e. going on a long plane flight would result in more exposure.
1. It used the Plutonium isotope 239, rather than the more common 235. Pu239 is more reactive (has a much shorter half-life) than 235; this makes it better fuel for an RTG but makes it much more dangerous if you inhale a particle.
2. It used an especially large amount of this especially dangerous isotope of Plutonium.
Pu-235 has a 25.3 minute half-life. The one they use is Pu-238 with a half life of 87.7 years, so that the power provided during the first 10 years of the mission is more or less constant. Pu-239 has a half life of 24100 years. My data comes from 1996 edition of the Chart of the Nuclides (by Lockehhed Martin & GE Nuclear). I tend to trust it, which means that you are wrong. Also, Pu-235 is not common at all. As with any other isotope of Plutonium, it does not exist in nature. The most "common" in the sense of quantity available is Pu-239, which is used for weapons.
Perhaps you can do a better job of sending a probe 60 million miles away and communicating with it with a 15 minute signal lag? Don't bash NASA, they aren't morons, they just have finite (very little) resources which they have to spread among many projects. Most of that goes to ISS and only very little is left for probes. Also, reentry with smooth landing on a planet from orbit is probably one of the hardest things to do for a space probe. Even on Earth, cosmonauts crash-land and astronauts used to do a splash-down, both in extremely well shielded capsules. Not exactly a smooth landing and not good enough for a probe. Moreover, for Earth reentry we have almost instantaneous data/telemetry link.
I'm sorry, but both the Sun and Venus are brighter than Sirius. If it's the third brightest, that means only the Moon and the Sun would be brighter. Also, I think Jupiter is brighter than Sirius when we are close to it.
A nuclear reactor is not a nuclear bomb. For a bomb you need highly enriched fuel, which is hard to make, unlike for power plants where you need only about 4% enriched. And a reactor does not help you build bombs. So it's not a big deal.
As I said, if we continue using nuclear fuel irresponsibly (i.e. once-through), there will not be enough cheap U-235 to last us 50 years. If we use reprocessing it will last for thousands of years. Which one do you prefer, considering nuclear energy is probably the cleanest and cheapest major electricity source. Also, nuclear reactions more or less conserve mass and you don't add stuff when recycling, so the amount of waste from reprocessing will be the same, but the more you recycle, the more waste ends up with short half-life fission products, since U-238 is extracted. By the way, my nuclear engineering prof mentioned in class that Three Mile Island was basically a partial core meltdown (IIRC 20% core melted and penetrated the containment, not much leakage). The amount of radiation released was not that big. People can take significant amounts of radiation with no ill effects, but increased probability of cancer in the long run.
I think you are being a bit too biased trashing France like that. Reprocessing nuclear fuel has the advantage of minimizing nuclear waste dramatically. In a Uranium reactor, only a small fraction of the fissionable U-235 is used (less than 4%), while more fuel is produced under the form of Plutonium-239 (cfr breeder reactors). This Plutonium can be extracted and used as fuel again. This is done in Europe and Japan and Russia. The United States policy is to use a once-through fuel cycle. Once they have used the fuel the first time around, they throw it away. This is A LOT of nuclear waste, including perfectly good usable fuel. Also, the disadvantage of the once-through cycle is that at these rates, all of the U-235 fuel will be used up in about 50 years so we will no longer be able to start up a reactor. So the leader in sheer volume of waste (per unit power generated) is the United States. However, preprocessing plants have to separate highly radioactive byproducts, so these plants need to be very well designed. The French have the best reprocessing plants, much more advanced than any US plants. So don't underestimate them.
Re:Programmers Make Computers Slower Year by Year
on
Netscape 6 Vs. 4.7x
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· Score: 1
I run Win2K on a Pentium2/233 with 256 MB RAM. It works fine. It's only slow for certain processing intensive stuff. KDE and Gnome are much much slower on this same machine.
Re:Get out of the petri dish or die in the waste
on
On Asteroid Mining
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· Score: 1
We have thousnads of years' worth of nuclear fuel. Nuclear energy is one of the cleanest we've got especially if you have a reprocessing plant that makes new fuel out of the waste. So don't worry about petrolium being used up. We have enough fuel to last us a VERY long time.
What the fuck are you talking about? Enigma was a German machine, not British. All of the Enigmas England owns were stolen from the Germans during WWII. When Germany was defeated most of the works of art that you are talking about ended up in the Hermitage in Russia and in private hands in the US. Haven't you heard of lawsuits in the US where some old Jewish people sue some other Americans for a "stolen" work of art that their ancestors owned back in Germany?
Yeah but.biz looks and sounds so stupid, that no self-respecting business will buy it as their domain, unless they are also getting the.com/net/org. NSI is trying to extort more money again.
You're right, I was wrong. I checked (before you had posted) the definition and the refractive index defined with phase velocity, not group velocity (group velocity being the speed of light). So it is possible to have negative refractive index if the phase velocity is higher than c in the material.
I checked my physics book. I was right about the definition of the refractive index. However, I was wrong about which speed it uses. In fact it is based on the phase velocity, not on the group velocity of the wave packet. The phase velocity can be grater than the speed of light without braking relativity, so in fact a negative refractive index is theoretically possible, for wavelengths which are very strongly absorbed in the material we are considering. That is how apparently some materials can have negative index for certain very specific absorption wavelengths.
A negative refractive index for a MATERIAL would mean negative speed of light in the material by definition. What they have is not a material, but is lens made of "wires and rings". Therefore it is not fair to say that it has a refractive index as such. I can for example put a mirror in water and by tilting it just right I can deflect incoming light rays in the direction equivalent to index of -1. But this does not mean water is a perfect lens. I agree that such a technique might help with the diffraction problem, I just disagree with saying that the thing has a negative refractive index, because of the definition refractive index being what it is.
You are confusing JavaScript with Java applets. You don't have to load a JVM for javascript: the browsers usually run javascript themselves (IE has an ActiveX control that runs JScript, I'm not sure about netscape).
Mars has the longest period between launch windows - 2.2 years. All other planets have periods of about 1 year, or less for the inner planets. So we can launch to Pluto every year. But you are right we are running out of time for sending a worthwhile mission to Pluto since its atmoshere will be freezing. I think we are late already.
I would actually prefer alcohol or natural gas as an alternative fuel. Both give off water and carbon dioxide when burned, so they are much cleaner than gasoline. Many current car engines can run on alcohol without modification and alcohol is a renewable resource (can be made from sugar). Natural gas resources have yet to be explored, they usually occur near oil deposits. As to hydrogen peroxide, itself is not a fuel, but a strong oxidizer, so it won't burn. You need a fuel for it to burn. Like hydrogen. So you could possibly have two tanks -- fuel and oxidizer, like a normal rocket. It's so strong that causes severe burns to skin and eyes on contact, because of atomic oxygen that is given off. Gasoline is actually less dangerous if you make contact with it or inhale it. I wonder how powerful a normal combustion engine could become if one injected peroxide as oxidizer for the gasoline, instead of air...
Slashdot Mirror
I've yet to speak with someone with a three digit IQ over there.
Not a big surprize since half of all people have IQ < 100, since the tests are designed to have a mean of 100. (Assuming mean and median are about the same, which is reasonable in this case).
I stand by my word. But this algorithm you link to cannot factor a prime number. Nobody can factor a prime number. I posted that because the original poster referred to factoring a prime number and I was just making the point that RSA actually uses composite numbers that are a multiple of two large prime numbers. And the only way you can factor a prime N is N*1, but this doesn't count.
I will give you $100 billion if you post an algorithm to "breakdown a prime number" below:
Pu-242 is not fissile because it has an even number of nucleons. Therefore it cannot be used for a bomb. Bombs use Pu-239 as I said already, or Pu-241 (but I'm not sure about that one).
FYI, here is a list of the common fissile niclei:
U-233, U-235, Pu-239, Pu-241
Hmmm, don't you mean converting U-238 to Pu-239 using U-235 burning breeder reactors? Anyway, RTG's use either Plutonium carbide or dioxide, which are more or less ceramic compounds, and are made into large pellets when used as RTGs. These pellets will not break into dust on reentry. There have been cases of satellites using these crashing down with the RTG box recovered almost intact. Of course there are cases of satellites using older type RTGs (like SNAP-9) that have broken up and contaminated some area, but the level of radiation was not much above the average, i.e. going on a long plane flight would result in more exposure.
1. It used the Plutonium isotope 239, rather than the more common 235. Pu239 is more reactive (has a much shorter half-life) than 235; this makes it better fuel for an RTG but makes it much more dangerous if you inhale a particle. 2. It used an especially large amount of this especially dangerous isotope of Plutonium.
Pu-235 has a 25.3 minute half-life. The one they use is Pu-238 with a half life of 87.7 years, so that the power provided during the first 10 years of the mission is more or less constant. Pu-239 has a half life of 24100 years. My data comes from 1996 edition of the Chart of the Nuclides (by Lockehhed Martin & GE Nuclear). I tend to trust it, which means that you are wrong. Also, Pu-235 is not common at all. As with any other isotope of Plutonium, it does not exist in nature. The most "common" in the sense of quantity available is Pu-239, which is used for weapons.
Perhaps you can do a better job of sending a probe 60 million miles away and communicating with it with a 15 minute signal lag? Don't bash NASA, they aren't morons, they just have finite (very little) resources which they have to spread among many projects. Most of that goes to ISS and only very little is left for probes. Also, reentry with smooth landing on a planet from orbit is probably one of the hardest things to do for a space probe. Even on Earth, cosmonauts crash-land and astronauts used to do a splash-down, both in extremely well shielded capsules. Not exactly a smooth landing and not good enough for a probe. Moreover, for Earth reentry we have almost instantaneous data/telemetry link.
I'm sorry, but both the Sun and Venus are brighter than Sirius. If it's the third brightest, that means only the Moon and the Sun would be brighter. Also, I think Jupiter is brighter than Sirius when we are close to it.
A nuclear reactor is not a nuclear bomb. For a bomb you need highly enriched fuel, which is hard to make, unlike for power plants where you need only about 4% enriched. And a reactor does not help you build bombs. So it's not a big deal.
As I said, if we continue using nuclear fuel irresponsibly (i.e. once-through), there will not be enough cheap U-235 to last us 50 years. If we use reprocessing it will last for thousands of years. Which one do you prefer, considering nuclear energy is probably the cleanest and cheapest major electricity source. Also, nuclear reactions more or less conserve mass and you don't add stuff when recycling, so the amount of waste from reprocessing will be the same, but the more you recycle, the more waste ends up with short half-life fission products, since U-238 is extracted.
By the way, my nuclear engineering prof mentioned in class that Three Mile Island was basically a partial core meltdown (IIRC 20% core melted and penetrated the containment, not much leakage). The amount of radiation released was not that big. People can take significant amounts of radiation with no ill effects, but increased probability of cancer in the long run.
I think you are being a bit too biased trashing France like that. Reprocessing nuclear fuel has the advantage of minimizing nuclear waste dramatically. In a Uranium reactor, only a small fraction of the fissionable U-235 is used (less than 4%), while more fuel is produced under the form of Plutonium-239 (cfr breeder reactors). This Plutonium can be extracted and used as fuel again. This is done in Europe and Japan and Russia. The United States policy is to use a once-through fuel cycle. Once they have used the fuel the first time around, they throw it away. This is A LOT of nuclear waste, including perfectly good usable fuel. Also, the disadvantage of the once-through cycle is that at these rates, all of the U-235 fuel will be used up in about 50 years so we will no longer be able to start up a reactor. So the leader in sheer volume of waste (per unit power generated) is the United States. However, preprocessing plants have to separate highly radioactive byproducts, so these plants need to be very well designed. The French have the best reprocessing plants, much more advanced than any US plants. So don't underestimate them.
I run Win2K on a Pentium2/233 with 256 MB RAM. It works fine. It's only slow for certain processing intensive stuff. KDE and Gnome are much much slower on this same machine.
We have thousnads of years' worth of nuclear fuel. Nuclear energy is one of the cleanest we've got especially if you have a reprocessing plant that makes new fuel out of the waste. So don't worry about petrolium being used up. We have enough fuel to last us a VERY long time.
What the fuck are you talking about? Enigma was a German machine, not British. All of the Enigmas England owns were stolen from the Germans during WWII. When Germany was defeated most of the works of art that you are talking about ended up in the Hermitage in Russia and in private hands in the US. Haven't you heard of lawsuits in the US where some old Jewish people sue some other Americans for a "stolen" work of art that their ancestors owned back in Germany?
Yeah but .biz looks and sounds so stupid, that no self-respecting business will buy it as their domain, unless they are also getting the .com/net/org. NSI is trying to extort more money again.
You're right, I was wrong. I checked (before you had posted) the definition and the refractive index defined with phase velocity, not group velocity (group velocity being the speed of light). So it is possible to have negative refractive index if the phase velocity is higher than c in the material.
I checked my physics book. I was right about the definition of the refractive index. However, I was wrong about which speed it uses. In fact it is based on the phase velocity, not on the group velocity of the wave packet. The phase velocity can be grater than the speed of light without braking relativity, so in fact a negative refractive index is theoretically possible, for wavelengths which are very strongly absorbed in the material we are considering. That is how apparently some materials can have negative index for certain very specific absorption wavelengths.
A negative refractive index for a MATERIAL would mean negative speed of light in the material by definition. What they have is not a material, but is lens made of "wires and rings". Therefore it is not fair to say that it has a refractive index as such. I can for example put a mirror in water and by tilting it just right I can deflect incoming light rays in the direction equivalent to index of -1. But this does not mean water is a perfect lens. I agree that such a technique might help with the diffraction problem, I just disagree with saying that the thing has a negative refractive index, because of the definition refractive index being what it is.
Ha-ha, beat you all. Damn what's wrong with the lameness filter
You are confusing JavaScript with Java applets. You don't have to load a JVM for javascript: the browsers usually run javascript themselves (IE has an ActiveX control that runs JScript, I'm not sure about netscape).
There're also lots of teenagers whose parents won't let me get a real ISP, but really, really want one. Badly. Gee, I'd hate to be them.
Ha-ha-ha. This is called a Freudian slip. (My bold).
Mars has the longest period between launch windows - 2.2 years. All other planets have periods of about 1 year, or less for the inner planets. So we can launch to Pluto every year. But you are right we are running out of time for sending a worthwhile mission to Pluto since its atmoshere will be freezing. I think we are late already.
Also, peroxide decomposes violently if heated in a closed container, so it has to be kept in a vented container.
I would actually prefer alcohol or natural gas as an alternative fuel. Both give off water and carbon dioxide when burned, so they are much cleaner than gasoline. Many current car engines can run on alcohol without modification and alcohol is a renewable resource (can be made from sugar). Natural gas resources have yet to be explored, they usually occur near oil deposits.
As to hydrogen peroxide, itself is not a fuel, but a strong oxidizer, so it won't burn. You need a fuel for it to burn. Like hydrogen. So you could possibly have two tanks -- fuel and oxidizer, like a normal rocket. It's so strong that causes severe burns to skin and eyes on contact, because of atomic oxygen that is given off. Gasoline is actually less dangerous if you make contact with it or inhale it. I wonder how powerful a normal combustion engine could become if one injected peroxide as oxidizer for the gasoline, instead of air...
Considreing it's used as rocket fuel, I don't think that most people would like to strap themselves in a car running on that...