At how those against nuclear power like to cite the Chernobyl accident, as apparently they feel it is proper to equate a plant that was a zillion miles from a water source to the San Onofre plant which is cooled by the Pacific Ocean.
Not the point. The problem with the Chernobyl plant was the bloody stupid design, which had a positive feedback loop: if things go wrong, then things will tend to go even more wrong and meltdown. Dumping water on a reactor to cool it is possibly the most idiotic thing you could do: you'll get a steam explosion and guarantee radioactive material being spread around.
The reason nuclear fission plants are safe is that with sensible designs you have a negative feedback loop, i.e. if the reactor starts producing too many neutrons then the damping effects increase and the reactor tends to return to normal.
The feedback loops in both cases, btw, are not computer-controlled or whatever, they're a result of the physics of the different designs of reactor: so you can't get a blue-screen-causes-explosion too easily.
If it's too hot to live where you are in the summer, the right answer might be 'don't live there' rather than 'turn up the A/C'.
If it's too hot to live where you are, the right answer is turn up the AC powered by the solar cells on your roof. Solar power's fine for domestic use in sunny areas; it's when you start trying to cover industrial demand and non-sunny areas that the numbers don't work.
People will give up their SUVs when they are too expensive to run. Which will happen when oil prices get stupidly high (because the US govt is not going to impose any significant pollution tax on cars). In other words, within 50 years.
Just to be fair here, while I acknowledge that MS Access is overpriced, inconvenient, produces massively bloated files, and implements a whole lot of stuff no-one wants while failing to implement real SQL...
it does give the right results if given correct MS dialect SQL.
I think it was more like three years ago he played Kramnik with the world championship at stake.
Most people also think that the reason he lost that was that he accepted Kramnik's challenge to play shorter games than standard: Kramnik thinks faster than Kasparov, but not as deeply, and hasn't beaten him in any matches with normal time rules.
He doesn't get many one-on-one matches any more, because no-one wants to be beaten repeatedly. He does enter tournaments, and tends to win those.
The point is that power = current x voltage drop.
When you look at the power wasted due to the insulator being imperfect, you've got maximum voltage drop (+V line to ground) but very small current; power wastd flowing along a wire has relatively large current but very small voltage drop (due to small resistance of wires). However setting or resetting a bit will have the large voltage drop and the large current, hence very significant power lost. That last bit is what is being removed.
In fact, you can sometimes cool things down by running a circuit backwards - a thermocouple, for example.
That's not the point. No-one really cares much about the 30W of power you don't have to pay for, or the heating you do, that's going to cost/gain you not much even if your computer is permanently on.
The point is that the 30W of power does not have to be got off the chip and dissipated without letting the chip get too hot and burn up. If you could get your Pentium IV to run on only 0.5W, say, at normal speed, then you could overclock it by a factor of 60 or so, with no extra cooling equipment. (well, if the rest of the computer didn't die)
If you try to design one, you run into problems. Let's say you try to make a ratchet-wheel sort of thing, so random motions of particles can knock the wheel round one way, but not the other because of the ratchet - and you generate energy from this nice one-way motion. But then you find that either your contraption is too stiff (the ratchet has to be lifted) to move at all, or the ratchet occasionally gets jumped by the random motions and the wheel goes backwards - and no net motion occurs. You can actually prove that there isn't any design that will output energy (let's say in the form of a turning shaft for convenience, but any 'better' form of energy than heat will do) given only energy in the form of a constant temperature background. You can of course generate energy given a heat-sink as well as a source; e.g. Carnot cycle, or a thermoelectric junction. This will always cause the cold side to heat up and the hot side to cool down, though (again provable).
Hmm.. no.
Information =/= energy; this is easy to prove. Just observe that you can consider any (finite) string of bits to represent any (finite) message, as you're allowed to choose the encoding, and you see that the information content (the ordering of the bits) has the same energy content as the string of bits given by sending as many 1s as in your message, followed by as many zeroes.
However, information processing does require energy, and that is where your parallel is worth considering.
As far as Hawking radiation goes: firstly the entropy situation was never a real theoretical problem, more an inconvenience (the second law of thermodynamics is a statistical law which holds in Newtonian dynamics and which would be nice to have in all cases). Secondly, the information is not returned by the Hawking radiation. The point is that the probability of there being more order in the Hawking radiation than in the swallowed matter approaches zero as time (and matter swallowed and re-emitted as Hawking radiation) approaches infinity. Thus instead of matter ending up in a black hole somehow removing entropy from the universe, you can consider all mass in a black hole to 'have no order', hence any mass falling into a black hole causes total entropy to increase.
Next thing to think about: if you can encode information in any way you choose, what exactly does it mean for something to be disordered?
Answer: this is hard. On one hand, you can examine the probability of certain events (such as all the 1s being in a block, not spread around). This attempts to give a measure of disorder to matter at a given instant. On the other hand, you can examine the processes affecting the matter as time goes on. Here you find that certain processes output energy, and others require energy input. The processes that output energy tend to cause the disorder of the matter to increase in any fixed metric for order (result in more-probable states), and those that require energy tend to decrease that disorder (result in less-probable states). From this point of view, entropy is likely to increase when a sequence of processes occurs (second law of thermodynamics). The sequence of processes is approximately equivalent to performing a sequence of calculations on the data represented by the matter; entropy increase is due to the fact that highly-ordered states tend to look dissimilar, while disordered states are all fairly similar in any given metric. Then if you want to look at parallels with Shannon's theorem, observe that you can consider a calculation to be the same as encoding your data in a different way, possibly throwing away some of the output. Here it becomes obvious that a reversible calculation tends to preserve entropy, while irreversible ones increase it, so that transmitting accurate information through a channel requires energy input, more energy for better transmission (in the sense of more expected accurate data).
If I've already had a megabyte of spammed crap in my email, I really don't need to waste another ten megabytes looking up all the websites in all the spams.
2. Observe that SCO is failing to get money from eveyone using GPLed software.
3. Write registered letter to SCO requiring that they exercise due diligence, i.e. get the money. If SCO do not get the money, then they owe you for the dividend you didn't get, and then everyone owning SCO shares jumps on them and demands money; SCO go down the toilet.
If SCO do try to get the money, i.e. take people to court, they have to show the GPL is invalid, and either they can't and set a precedent that leaves them in the shit, or they can and the original copyright holders are free to demand royalties - and enough law firms take on class action suits that are clearly winnable with fee dependent on winning to make this an attractive option.
If you look at pi then choose your decoding to get LoTR, then you will find it 'encoded'. Otherwise, you probably won't.
pi is known to be transcendental. This does not imply that you can find whatever you want in it.
0.110001000000000000000001000....
= sum[n=1,inf] (10^-n!)
is also transcendental; but I don't think you'll find any currently-used coding which can get LoTR back out of it.
pi is certainly a more interesting transcendental number than the above, though, and there have been suggestions that maybe you can find any given string of digits in pi if you look far enough along. However AFAIK no such suggestion has been proved.
'Radio frequencies' could be anything up from 100 KHz or so - the point is that at the lower frquencies the ability of a 1mm long wire to act as an antenna and radiate is miniscule (radiation output is roughly proportional to the wire length over the wavelength when that ratio is 1 ).
So the solution amounts to making the internal traces contain no straight bits longer than x - which gets to be a real pain when you're trying to get bus connections in, in particular.
Could it be possible that explaining gravity is beyond the scope of our current models, and no amount of tap dancing is going to make it fit with their contexts?
Probably.
But you can't do that, no no no! Don't even bother pondering alternative models or colleagues will jump up and down on your skull, screaming "Crackpot!"
String theory? Branes? No-one got seriously attacked over them. Everyone accepts that if current_model isn't working, you need a new model. Of course, if you're just spouting crap which doesn't make any sense (or isn't mathematically consistent) then you'll get dumped on, but produce an idea which might, or a set of equations which might/demonstrably do approximate to known models in low-energy situations and you're doing useful work. (if your equations do not approximate to GR in low energy situations, then everyday life proves them wrong, in the same way that GR approximates to special relativity when there's not too much mass around, and that to Newton's laws when energies are low).
There are a few models competing; your 'lumbering big one' is simply the model that's been fairly effective in the past and hasn't been completely blown to bits yet (but probably isn't correct), and various newer models are being considered. If you want hundreds of models, though, you have to think of hundreds of radically new ideas which still produce real-life results in real-life situations. This is not easy.
I take it you've never tried anything much beyond pop-sci and high school physics, or you would know that.
Space might be infinite - AFAIK, we don't know yet; general relativity doesn't help (it tells us about local properties of space, from which we can deduce some global properties, but both finite and infinite spaces are mathematically possible). For a simple finite analogy, the standard blowing-up-a-balloon thing works.
For infinite space with expansion: what's meant isn't that space-now is bigger than space-past, if you look at the 'total area' (infinite, and infinite) but that wherever you look from, you find that (on average) everything is moving away from everything else.
Simple 2-d example of infinite space which is expanding: space is the 2-d plane, and everything in it moves directly away from the origin at a speed linearly proportional to the distance from the origin. Simulate that on a computer, and you'll see it works.
(note: AIUI, there are interesting effects that come into play in the GR equations if space is expanding, above and beyond the obvious stuff-moving; I'm not into that side of maths, though)
Your H's here are deuterium - if you want to use symbols, use D (and T for tritium).
The first reaction is theoretically possible but unlikely; you tend to end up with either helium-3 plus neutron or tritium and normal hydrogen.
The second is wrong: the electron shouldn't be there, as the gas is ionised and hence the electrons aren't associated with the nuclei. It's also very unlikely, as the energy input required to separate a small nucleus is large.
Third reaction: correct and frequent. This is the cause of (most of) the neutrons produced. The rest come from T+D -> 4-He + n. However this only occurs because of tritium produced previously from D+D -> T + H, and hence it's unlikely to occur much (the energy barrier is lower, though, IIRC).
It is fusion - that's where the neutrons are coming from. But at 4 neutrons produced a second, the fusion rate's not exactly spectacular. To get a significant number of fusion reactions per second you need a minimum temperature (ionised gas is just about within this) and a high pressure; increase either temperature or pressure and fusion rate increases. If you look at a Boltzmann distribution, what you have in this case is only those nuclei with energies in the top %small of the graph can fuse (large energy barrier to overcome due to electric repulsion between nuclei) and the probability of two nuclei with sufficiently large total energy colliding is small. If you increase temperature, the Boltzmann plot shifts and more nuclei have the required energy; if you increase pressure, the probability of collision increases.
Well, they would do 'something', namely tell every user individually that they don't give a damn.
That idea's about as useful as you telling everyone to write to the government individually and explaining that you disagree with their laws and you want to renegotiate them.
Now, if everyone were to do something vaguely useful, like complaining to ICANN or their ISPs (who can return 404 for anything hitting SiteFinder) that might help.
Slashdot Mirror
Not the point. The problem with the Chernobyl plant was the bloody stupid design, which had a positive feedback loop: if things go wrong, then things will tend to go even more wrong and meltdown. Dumping water on a reactor to cool it is possibly the most idiotic thing you could do: you'll get a steam explosion and guarantee radioactive material being spread around.
The reason nuclear fission plants are safe is that with sensible designs you have a negative feedback loop, i.e. if the reactor starts producing too many neutrons then the damping effects increase and the reactor tends to return to normal.
The feedback loops in both cases, btw, are not computer-controlled or whatever, they're a result of the physics of the different designs of reactor: so you can't get a blue-screen-causes-explosion too easily.
If it's too hot to live where you are, the right answer is turn up the AC powered by the solar cells on your roof. Solar power's fine for domestic use in sunny areas; it's when you start trying to cover industrial demand and non-sunny areas that the numbers don't work.
People will give up their SUVs when they are too expensive to run. Which will happen when oil prices get stupidly high (because the US govt is not going to impose any significant pollution tax on cars). In other words, within 50 years.
Just to be fair here, while I acknowledge that MS Access is overpriced, inconvenient, produces massively bloated files, and implements a whole lot of stuff no-one wants while failing to implement real SQL...
it does give the right results if given correct MS dialect SQL.
I think it was more like three years ago he played Kramnik with the world championship at stake.
Most people also think that the reason he lost that was that he accepted Kramnik's challenge to play shorter games than standard: Kramnik thinks faster than Kasparov, but not as deeply, and hasn't beaten him in any matches with normal time rules.
He doesn't get many one-on-one matches any more, because no-one wants to be beaten repeatedly. He does enter tournaments, and tends to win those.
The point is that power = current x voltage drop.
When you look at the power wasted due to the insulator being imperfect, you've got maximum voltage drop (+V line to ground) but very small current; power wastd flowing along a wire has relatively large current but very small voltage drop (due to small resistance of wires). However setting or resetting a bit will have the large voltage drop and the large current, hence very significant power lost. That last bit is what is being removed.
In fact, you can sometimes cool things down by running a circuit backwards - a thermocouple, for example.
That's not the point. No-one really cares much about the 30W of power you don't have to pay for, or the heating you do, that's going to cost/gain you not much even if your computer is permanently on.
The point is that the 30W of power does not have to be got off the chip and dissipated without letting the chip get too hot and burn up. If you could get your Pentium IV to run on only 0.5W, say, at normal speed, then you could overclock it by a factor of 60 or so, with no extra cooling equipment. (well, if the rest of the computer didn't die)
If you try to design one, you run into problems. Let's say you try to make a ratchet-wheel sort of thing, so random motions of particles can knock the wheel round one way, but not the other because of the ratchet - and you generate energy from this nice one-way motion. But then you find that either your contraption is too stiff (the ratchet has to be lifted) to move at all, or the ratchet occasionally gets jumped by the random motions and the wheel goes backwards - and no net motion occurs. You can actually prove that there isn't any design that will output energy (let's say in the form of a turning shaft for convenience, but any 'better' form of energy than heat will do) given only energy in the form of a constant temperature background. You can of course generate energy given a heat-sink as well as a source; e.g. Carnot cycle, or a thermoelectric junction. This will always cause the cold side to heat up and the hot side to cool down, though (again provable).
Hmm.. no.
Information =/= energy; this is easy to prove. Just observe that you can consider any (finite) string of bits to represent any (finite) message, as you're allowed to choose the encoding, and you see that the information content (the ordering of the bits) has the same energy content as the string of bits given by sending as many 1s as in your message, followed by as many zeroes.
However, information processing does require energy, and that is where your parallel is worth considering.
As far as Hawking radiation goes: firstly the entropy situation was never a real theoretical problem, more an inconvenience (the second law of thermodynamics is a statistical law which holds in Newtonian dynamics and which would be nice to have in all cases). Secondly, the information is not returned by the Hawking radiation. The point is that the probability of there being more order in the Hawking radiation than in the swallowed matter approaches zero as time (and matter swallowed and re-emitted as Hawking radiation) approaches infinity. Thus instead of matter ending up in a black hole somehow removing entropy from the universe, you can consider all mass in a black hole to 'have no order', hence any mass falling into a black hole causes total entropy to increase.
Next thing to think about: if you can encode information in any way you choose, what exactly does it mean for something to be disordered?
Answer: this is hard. On one hand, you can examine the probability of certain events (such as all the 1s being in a block, not spread around). This attempts to give a measure of disorder to matter at a given instant. On the other hand, you can examine the processes affecting the matter as time goes on. Here you find that certain processes output energy, and others require energy input. The processes that output energy tend to cause the disorder of the matter to increase in any fixed metric for order (result in more-probable states), and those that require energy tend to decrease that disorder (result in less-probable states). From this point of view, entropy is likely to increase when a sequence of processes occurs (second law of thermodynamics). The sequence of processes is approximately equivalent to performing a sequence of calculations on the data represented by the matter; entropy increase is due to the fact that highly-ordered states tend to look dissimilar, while disordered states are all fairly similar in any given metric. Then if you want to look at parallels with Shannon's theorem, observe that you can consider a calculation to be the same as encoding your data in a different way, possibly throwing away some of the output. Here it becomes obvious that a reversible calculation tends to preserve entropy, while irreversible ones increase it, so that transmitting accurate information through a channel requires energy input, more energy for better transmission (in the sense of more expected accurate data).
If I've already had a megabyte of spammed crap in my email, I really don't need to waste another ten megabytes looking up all the websites in all the spams.
1. Buy shares in SCO.
2. Observe that SCO is failing to get money from eveyone using GPLed software.
3. Write registered letter to SCO requiring that they exercise due diligence, i.e. get the money. If SCO do not get the money, then they owe you for the dividend you didn't get, and then everyone owning SCO shares jumps on them and demands money; SCO go down the toilet.
If SCO do try to get the money, i.e. take people to court, they have to show the GPL is invalid, and either they can't and set a precedent that leaves them in the shit, or they can and the original copyright holders are free to demand royalties - and enough law firms take on class action suits that are clearly winnable with fee dependent on winning to make this an attractive option.
If you look at pi then choose your decoding to get LoTR, then you will find it 'encoded'. Otherwise, you probably won't. pi is known to be transcendental. This does not imply that you can find whatever you want in it. 0.110001000000000000000001000.... = sum[n=1,inf] (10^-n!) is also transcendental; but I don't think you'll find any currently-used coding which can get LoTR back out of it. pi is certainly a more interesting transcendental number than the above, though, and there have been suggestions that maybe you can find any given string of digits in pi if you look far enough along. However AFAIK no such suggestion has been proved.
'Radio frequencies' could be anything up from 100 KHz or so - the point is that at the lower frquencies the ability of a 1mm long wire to act as an antenna and radiate is miniscule (radiation output is roughly proportional to the wire length over the wavelength when that ratio is 1 ). So the solution amounts to making the internal traces contain no straight bits longer than x - which gets to be a real pain when you're trying to get bus connections in, in particular.
Could it be possible that explaining gravity is beyond the scope of our current models, and no amount of tap dancing is going to make it fit with their contexts? Probably. But you can't do that, no no no! Don't even bother pondering alternative models or colleagues will jump up and down on your skull, screaming "Crackpot!" String theory? Branes? No-one got seriously attacked over them. Everyone accepts that if current_model isn't working, you need a new model. Of course, if you're just spouting crap which doesn't make any sense (or isn't mathematically consistent) then you'll get dumped on, but produce an idea which might, or a set of equations which might/demonstrably do approximate to known models in low-energy situations and you're doing useful work. (if your equations do not approximate to GR in low energy situations, then everyday life proves them wrong, in the same way that GR approximates to special relativity when there's not too much mass around, and that to Newton's laws when energies are low). There are a few models competing; your 'lumbering big one' is simply the model that's been fairly effective in the past and hasn't been completely blown to bits yet (but probably isn't correct), and various newer models are being considered. If you want hundreds of models, though, you have to think of hundreds of radically new ideas which still produce real-life results in real-life situations. This is not easy. I take it you've never tried anything much beyond pop-sci and high school physics, or you would know that.
We could. It'd help. Do you have $many-billion to spare putting equipment up that needs to be quite big?
Space might be infinite - AFAIK, we don't know yet; general relativity doesn't help (it tells us about local properties of space, from which we can deduce some global properties, but both finite and infinite spaces are mathematically possible). For a simple finite analogy, the standard blowing-up-a-balloon thing works. For infinite space with expansion: what's meant isn't that space-now is bigger than space-past, if you look at the 'total area' (infinite, and infinite) but that wherever you look from, you find that (on average) everything is moving away from everything else. Simple 2-d example of infinite space which is expanding: space is the 2-d plane, and everything in it moves directly away from the origin at a speed linearly proportional to the distance from the origin. Simulate that on a computer, and you'll see it works. (note: AIUI, there are interesting effects that come into play in the GR equations if space is expanding, above and beyond the obvious stuff-moving; I'm not into that side of maths, though)
Your H's here are deuterium - if you want to use symbols, use D (and T for tritium). The first reaction is theoretically possible but unlikely; you tend to end up with either helium-3 plus neutron or tritium and normal hydrogen. The second is wrong: the electron shouldn't be there, as the gas is ionised and hence the electrons aren't associated with the nuclei. It's also very unlikely, as the energy input required to separate a small nucleus is large. Third reaction: correct and frequent. This is the cause of (most of) the neutrons produced. The rest come from T+D -> 4-He + n. However this only occurs because of tritium produced previously from D+D -> T + H, and hence it's unlikely to occur much (the energy barrier is lower, though, IIRC).
It is fusion - that's where the neutrons are coming from. But at 4 neutrons produced a second, the fusion rate's not exactly spectacular. To get a significant number of fusion reactions per second you need a minimum temperature (ionised gas is just about within this) and a high pressure; increase either temperature or pressure and fusion rate increases. If you look at a Boltzmann distribution, what you have in this case is only those nuclei with energies in the top %small of the graph can fuse (large energy barrier to overcome due to electric repulsion between nuclei) and the probability of two nuclei with sufficiently large total energy colliding is small. If you increase temperature, the Boltzmann plot shifts and more nuclei have the required energy; if you increase pressure, the probability of collision increases.
Well, they would do 'something', namely tell every user individually that they don't give a damn. That idea's about as useful as you telling everyone to write to the government individually and explaining that you disagree with their laws and you want to renegotiate them. Now, if everyone were to do something vaguely useful, like complaining to ICANN or their ISPs (who can return 404 for anything hitting SiteFinder) that might help.