That's usually not called DRM. DRM is usually designed to control access to a document that resides on someone else's computer, not one you control. If the goal is merely to provide trust, then of course some sort of PKI is a good answer. If, however, the goal is "you can read this document but you can't modify it and use it elsewhere without my permission" then he's as doomed as the record companies.
And the difference between "read" and "full" is what, again? We're not talking about a file system here; we're talking about a document that you've given the other person, that you're trying to allow them to "read" but not "read".
As another poster put it, DRM is the Alice / Bob / Eve problem... where Bob and Eve are the same person. It can't work long term, and to the extent it works in the short term it's by hiding the implementation.
Well, the thing is you're not actually allowed to imagine that (at least not and have normal equations hold). This is the distinction between inertial and non-inertial reference frames.
To translate to a non-inertial frame you have to add artificial force terms -- centrifugal force is the name for the apparent force that acts on objects in a rotating reference frame (well, also Coriolis forces). Centripetal force is its counterpart, the force required to accelerate objects in an inertial frame so that they follow the rotating path.
It's much the same as gravity and an accelerated non-inertial reference frame being indistinguishable to an isolated observer. It may help to remember that momentum and angular momentum are distinct concepts; the fact that there is no absolute position or velocity reference does *not* imply that there is no such thing as being not spinning.
Earth isn't "moving through space". There is no universal reference frame. (At least, so say both Newtonian mechanics and GR.) Earth is moving relative to the sun, the galaxy, the local group... but not "space".
The obvious answer to all this, and where most serious investigations of time travel wind up, is that you need a coupled pair of machines; you leave one and arrive at the other. Think of a wormhole, with the two different ends at different points in both space and time. Yes, this means you can't travel to a time before the first time machine.
To start with: I'm not a Christian, but I find some theological topics like this interesting.
To me, it would make sense to say that the fall is as literal as Adam. The fall comes hand in hand with free will; if free will appeared as a gradual process through evolution, then so too was the fall a gradual process.
This makes sense from other perspectives as well -- we treat young children as innocent, even if their actions by an informed party would be wrong. As they grow older, they become more responsible for their actions, and so (if you're the type who believes in "sin") more capable of sin. It's not an instant process; we'll be more lenient with a 10-year-old than a 20-year-old, but we still expect them to understand right and wrong for the most part. If you're willing to take other parts of the Bible as metaphorical, I see no contradiction in taking the fall and original sin and the Eden story as allegorical for slow processes that came with the evolution of free will.
Re:You need a simulation for this?
on
Modeling Urban Panic
·
· Score: 4, Interesting
Of course you do.
Any time you want to answer the question "What will happen to X in the event of Y?" you either need to try it, or you need a model. Your model ("crowd moves away") probably gives correct results, but not detailed ones. If you want more detailed results, with answers to more detailed questions (How fast? Which direction? How does it change with pedestrian density? How do obstacles matter?) then you need a better model.
If you want to improve pedestrian traffic, police response, crowd control... This model could be quite helpful.
I certainly wouldn't say it's not done... but I've never seen an example of it. For inexpensive devices, the temperature isn't controlled, but the coefficient is balanced against something with the opposite coefficient. For more expensive devices, the temperature is controlled and kept above ambient because that's easier and cheaper. I can't imagine any case where that wouldn't work, unless perhaps you needed to run in a very hot environment -- but then I would think you'd want to cool the entire enclosure, and then heat the part if needed for precision.
It's a very interesting idea, and I'd love to see examples (and especially read why that route was chosen).
It's also worth noting that I think this article is mostly talking about heat management, not temperature control -- trying to cool the parts of the chip that generate too much heat actively rather than by conduction. A very different, but equally interesting problem.
But you can do burns that are neither. Generally they wouldn't be minimum-delta-v trajectories, but the trajectory does require that amount of delta-v. The only obvious useful example I can think of is shifting the orbital plane.
I've only glanced at the data sheet, but unless I'm severely mistaken, that chip *compensates* for temperature rather than controlling it. Every other thermocouple CJC chip I've seen does the same basic thing. Temperature compensated voltage references follow the same basic patter of balancing a bandgap or zener with a Vbe drop and possibly some second order effects. The very best such chips (eg the Linear Technology LTZ1000; I'm sure there are other similar ones) use a heater. Temperature-controlled crystal oscillators also use a heater. This method ensures constant temperature, but it's far cheaper, simpler, and more effective to maintain the temperature *higher* than ambient.
I've seen discussions of using on-chip peltiers for heat management before, but I don't think I've actually seen it done.
No, he wants to make the House of Representatives more fair. The House is supposed to be apportioned according to population, with each state receiving at least one representative. The Senate, on the other hand, has two representatives per state, regardless of population. Each state gets electoral votes equal to its representatives plus senators -- and that's where the small-state bias in the Presidential election comes from.
If you want to remove that bias, change the number of electoral votes to be equal to the number of representatives (or just remove the electoral college all together, or something else entirely). Don't advocate making the House apportionment any more unfair than it needs to be -- that's just silly.
Your math is slightly off. Carnot's theorem gives the max efficiency as (Th - Tc) / (Th), or (200 / 473) = 42%. That is, the fraction of the energy you can remove is exactly equal to the fraction of the temperature you can remove. Plugging in 873 for Th (aka 600C) and 300K Tc (a very good radiator), I get 65%, which is on par with TFA's 60% number.
The interesting question is how close to theoretical they can get...
You're exactly right for noise voltage, but since power = v^2/r, and v ~ sqrt(r), power is independent of resistance. Lower valued resistors produce lower voltage noise (which usually matters) and higher current noise (which usually doesn't matter as much), and so are better for noise in the vast majority of circuit designs. The power is then P = kTRB. The factor of two difference is based on half the power going into the resistor and half into the impedance-matched amplifier input, and can be removed or not as appropriate.
And I agree completely, I'd love to see some noise specs to judge the part by. Alas, this is a popular press article, not a data sheet...
Actually no. The "warm" sound is harmonic distortion. Whether this is a good thing or not I'll leave up to others, but it is distortion in the sense that it's not the same signal that came in, but it's related to it. Noise, on the other hand, is unrelated to the input signal and not coherent. Thermal noise is precisely white noise, aka "hiss".
I'd say the question of ETI is not only inherently interesting, but important as well, since it has direct implications for our continued survival as a species, and even what we should do to maximize our chances.
I'll take species survival over a lot of things, including a cure for cancer.
Well, getting better than 16 bits takes work, but isn't exactly that hard. And since computers like to work in 8-bit chunks, it should be no surprise that 24 bits was the next choice. And even if all you plan to do is adjust the volume on the different tracks, apply an equalization curve, and then mix a few tracks together, you should be doing all that in 24 bits. Sure, 24 bits is ovrekill, but it's easily better than 16 bits, and a 19-bit sample size would just be silly.
Use 24 bits during all the processing -- it's easy enough, and there's no reason to add quantization artifacts at the 16-bit level. But long before you care about the difference between 16 and 24 bit at the input and output, you need to be putting serious effort into good power supplies, a clean acoustic environment, and some very high quality analog components (mics, speakers, amps, etc). As any audio geek can tell you, getting the analog portions of your equipment to be as good as the 16 bit, 44.1kHz CD signal is neither trivial nor cheap, even with improving electronics.
It's both, really. To be specific, it's the fact that you can point the rocket in whichever direction is most convenient -- whether that's along the current velocity vector or not. If you had limitations about what direction you could point it (perhaps a solar sail, perhaps because you didn't want to point a radioactive exhaust at a planet) the problem would get more complicated. In general, if you're optimizing your orbital changes for low delta-v required, you'll be burning either with or against your orbital velocity -- but that's just choosing low delta-v maneuvers to accomplish the goal. Even if you chose a high delta-v option (for example, to get there faster), you can still treat the delta-v as a scalar.
What it really amounts to is that the rocket equation and your propulsion system together allow your vehicle to change velocity by a certain amount; that's your delta-v. The direction part of the vector quantity of a specific burn (as opposed to the overall system budget) comes from your orientation system, be it RCS or gyroscopes or something else.
Hopefully that was relatively coherent... For an example of delta-v calculations at work, see eg Hohmann transfer orbits.
It's not explained in the article, but the reason for the very low temperature operation is resistor thermal noise. Basically, any resistor (or anything with vaguely resistor-like properties, for example the radio antenna itself) creates "thermal noise" from the thermally-induced effects of electrons bouncing around. At room temperature (300K), that noise is 4E-21 watts per 1Hz bandwidth -- or about -130dBm on a fairly narrow 10kHz bandwidth. The noise generated varies linearly with temperature, so if the entire input amplifier is operated at 300mK instead of 300K, you get an extra 30dB of signal-to-noise ratio, which is substantial when you're looking for very very weak signals.
Fun fact: with a $5 op-amp, a few resistors, and an audio amplifier, you can create your own, entirely quantum, true white noise source from the same effect. Guaranteed good for cryptographic random number generation, impressing your friends, and preventing dates!
Many people seem to have the mistaken impression that electronic voting doesn't change anything fundamental about vote fraud, it just changes how it happens. But, if the change is big enough, it becomes qualitatively different as well.
Well, delta-v is usually treated as a positive scalar value in orbital mechanics. The propellant needed to change your velocity by (say) 3 km/s is independent of whether you're speeding up, slowing down, or changing direction. So, while velocity is a vector quantity with direction and magnitude, delta-v is usually treated as a simple positive-valued scalar. (At least when the impulse comes from a high-thrust rocket engine; for very low thrust things like ion engines, or weird things like solar sails, the problem changes somewhat.)
Personally, my complaint isn't that wikia search sucks. I'm sure it does, but it's alpha. I think the concept is interesting, so I'll reserve judgement for a while.
My complaint is that Wikipedia has major flaws, mostly related to management and editing and such. It desperately needs help. I won't go into detail, everyone has heard the complaints before. My biggest complaint about Wikia search is twofold: Jimbo should be working to fix Wikipedia instead, and more importantly, I see no reason to believe Wikia search won't have all the same problems as Wikipedia all over again.
The reason I care is simply that I think Wikipedia is absolutely amazing, in spite of its (major) flaws. Please, please work on improving it. Wikipedia finally has enough good content, enough recognition, that it has become important to our society. I don't want to see it languish and fail because people went off chasing new neat ideas as soon as the problems with Wikipedia got difficult.
If you want to play that semantic game, no entropy sink is renewable. Call it renewable or sustainable or whatever, it's semantically useful to make the distinction between the category including coal and oil and the category including solar, hydro, etc.
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That's usually not called DRM. DRM is usually designed to control access to a document that resides on someone else's computer, not one you control. If the goal is merely to provide trust, then of course some sort of PKI is a good answer. If, however, the goal is "you can read this document but you can't modify it and use it elsewhere without my permission" then he's as doomed as the record companies.
And the difference between "read" and "full" is what, again? We're not talking about a file system here; we're talking about a document that you've given the other person, that you're trying to allow them to "read" but not "read".
As another poster put it, DRM is the Alice / Bob / Eve problem... where Bob and Eve are the same person. It can't work long term, and to the extent it works in the short term it's by hiding the implementation.
Well, the thing is you're not actually allowed to imagine that (at least not and have normal equations hold). This is the distinction between inertial and non-inertial reference frames.
To translate to a non-inertial frame you have to add artificial force terms -- centrifugal force is the name for the apparent force that acts on objects in a rotating reference frame (well, also Coriolis forces). Centripetal force is its counterpart, the force required to accelerate objects in an inertial frame so that they follow the rotating path.
It's much the same as gravity and an accelerated non-inertial reference frame being indistinguishable to an isolated observer. It may help to remember that momentum and angular momentum are distinct concepts; the fact that there is no absolute position or velocity reference does *not* imply that there is no such thing as being not spinning.
Earth isn't "moving through space". There is no universal reference frame. (At least, so say both Newtonian mechanics and GR.) Earth is moving relative to the sun, the galaxy, the local group... but not "space".
The obvious answer to all this, and where most serious investigations of time travel wind up, is that you need a coupled pair of machines; you leave one and arrive at the other. Think of a wormhole, with the two different ends at different points in both space and time. Yes, this means you can't travel to a time before the first time machine.
Can it be teleported without copying, and still count as original? If so, how is the copying teleport different?
To start with: I'm not a Christian, but I find some theological topics like this interesting.
To me, it would make sense to say that the fall is as literal as Adam. The fall comes hand in hand with free will; if free will appeared as a gradual process through evolution, then so too was the fall a gradual process.
This makes sense from other perspectives as well -- we treat young children as innocent, even if their actions by an informed party would be wrong. As they grow older, they become more responsible for their actions, and so (if you're the type who believes in "sin") more capable of sin. It's not an instant process; we'll be more lenient with a 10-year-old than a 20-year-old, but we still expect them to understand right and wrong for the most part. If you're willing to take other parts of the Bible as metaphorical, I see no contradiction in taking the fall and original sin and the Eden story as allegorical for slow processes that came with the evolution of free will.
Modern medicine and drug-resistant diseases.
Of course you do.
Any time you want to answer the question "What will happen to X in the event of Y?" you either need to try it, or you need a model. Your model ("crowd moves away") probably gives correct results, but not detailed ones. If you want more detailed results, with answers to more detailed questions (How fast? Which direction? How does it change with pedestrian density? How do obstacles matter?) then you need a better model.
If you want to improve pedestrian traffic, police response, crowd control... This model could be quite helpful.
I certainly wouldn't say it's not done... but I've never seen an example of it. For inexpensive devices, the temperature isn't controlled, but the coefficient is balanced against something with the opposite coefficient. For more expensive devices, the temperature is controlled and kept above ambient because that's easier and cheaper. I can't imagine any case where that wouldn't work, unless perhaps you needed to run in a very hot environment -- but then I would think you'd want to cool the entire enclosure, and then heat the part if needed for precision.
It's a very interesting idea, and I'd love to see examples (and especially read why that route was chosen).
It's also worth noting that I think this article is mostly talking about heat management, not temperature control -- trying to cool the parts of the chip that generate too much heat actively rather than by conduction. A very different, but equally interesting problem.
But you can do burns that are neither. Generally they wouldn't be minimum-delta-v trajectories, but the trajectory does require that amount of delta-v. The only obvious useful example I can think of is shifting the orbital plane.
I've only glanced at the data sheet, but unless I'm severely mistaken, that chip *compensates* for temperature rather than controlling it. Every other thermocouple CJC chip I've seen does the same basic thing. Temperature compensated voltage references follow the same basic patter of balancing a bandgap or zener with a Vbe drop and possibly some second order effects. The very best such chips (eg the Linear Technology LTZ1000; I'm sure there are other similar ones) use a heater. Temperature-controlled crystal oscillators also use a heater. This method ensures constant temperature, but it's far cheaper, simpler, and more effective to maintain the temperature *higher* than ambient.
I've seen discussions of using on-chip peltiers for heat management before, but I don't think I've actually seen it done.
No, he wants to make the House of Representatives more fair. The House is supposed to be apportioned according to population, with each state receiving at least one representative. The Senate, on the other hand, has two representatives per state, regardless of population. Each state gets electoral votes equal to its representatives plus senators -- and that's where the small-state bias in the Presidential election comes from.
If you want to remove that bias, change the number of electoral votes to be equal to the number of representatives (or just remove the electoral college all together, or something else entirely). Don't advocate making the House apportionment any more unfair than it needs to be -- that's just silly.
Your math is slightly off. Carnot's theorem gives the max efficiency as (Th - Tc) / (Th), or (200 / 473) = 42%. That is, the fraction of the energy you can remove is exactly equal to the fraction of the temperature you can remove. Plugging in 873 for Th (aka 600C) and 300K Tc (a very good radiator), I get 65%, which is on par with TFA's 60% number.
The interesting question is how close to theoretical they can get...
You're exactly right for noise voltage, but since power = v^2/r, and v ~ sqrt(r), power is independent of resistance. Lower valued resistors produce lower voltage noise (which usually matters) and higher current noise (which usually doesn't matter as much), and so are better for noise in the vast majority of circuit designs. The power is then P = kTRB. The factor of two difference is based on half the power going into the resistor and half into the impedance-matched amplifier input, and can be removed or not as appropriate.
And I agree completely, I'd love to see some noise specs to judge the part by. Alas, this is a popular press article, not a data sheet...
Actually no. The "warm" sound is harmonic distortion. Whether this is a good thing or not I'll leave up to others, but it is distortion in the sense that it's not the same signal that came in, but it's related to it. Noise, on the other hand, is unrelated to the input signal and not coherent. Thermal noise is precisely white noise, aka "hiss".
I'd say the question of ETI is not only inherently interesting, but important as well, since it has direct implications for our continued survival as a species, and even what we should do to maximize our chances.
I'll take species survival over a lot of things, including a cure for cancer.
Well, getting better than 16 bits takes work, but isn't exactly that hard. And since computers like to work in 8-bit chunks, it should be no surprise that 24 bits was the next choice. And even if all you plan to do is adjust the volume on the different tracks, apply an equalization curve, and then mix a few tracks together, you should be doing all that in 24 bits. Sure, 24 bits is ovrekill, but it's easily better than 16 bits, and a 19-bit sample size would just be silly.
Use 24 bits during all the processing -- it's easy enough, and there's no reason to add quantization artifacts at the 16-bit level. But long before you care about the difference between 16 and 24 bit at the input and output, you need to be putting serious effort into good power supplies, a clean acoustic environment, and some very high quality analog components (mics, speakers, amps, etc). As any audio geek can tell you, getting the analog portions of your equipment to be as good as the 16 bit, 44.1kHz CD signal is neither trivial nor cheap, even with improving electronics.
It's both, really. To be specific, it's the fact that you can point the rocket in whichever direction is most convenient -- whether that's along the current velocity vector or not. If you had limitations about what direction you could point it (perhaps a solar sail, perhaps because you didn't want to point a radioactive exhaust at a planet) the problem would get more complicated. In general, if you're optimizing your orbital changes for low delta-v required, you'll be burning either with or against your orbital velocity -- but that's just choosing low delta-v maneuvers to accomplish the goal. Even if you chose a high delta-v option (for example, to get there faster), you can still treat the delta-v as a scalar.
What it really amounts to is that the rocket equation and your propulsion system together allow your vehicle to change velocity by a certain amount; that's your delta-v. The direction part of the vector quantity of a specific burn (as opposed to the overall system budget) comes from your orientation system, be it RCS or gyroscopes or something else.
Hopefully that was relatively coherent... For an example of delta-v calculations at work, see eg Hohmann transfer orbits.
It's not explained in the article, but the reason for the very low temperature operation is resistor thermal noise. Basically, any resistor (or anything with vaguely resistor-like properties, for example the radio antenna itself) creates "thermal noise" from the thermally-induced effects of electrons bouncing around. At room temperature (300K), that noise is 4E-21 watts per 1Hz bandwidth -- or about -130dBm on a fairly narrow 10kHz bandwidth. The noise generated varies linearly with temperature, so if the entire input amplifier is operated at 300mK instead of 300K, you get an extra 30dB of signal-to-noise ratio, which is substantial when you're looking for very very weak signals.
Fun fact: with a $5 op-amp, a few resistors, and an audio amplifier, you can create your own, entirely quantum, true white noise source from the same effect. Guaranteed good for cryptographic random number generation, impressing your friends, and preventing dates!
you yuppie little shit.
And this is better because...?
Quantity has a quality all its own.
Many people seem to have the mistaken impression that electronic voting doesn't change anything fundamental about vote fraud, it just changes how it happens. But, if the change is big enough, it becomes qualitatively different as well.
Well, delta-v is usually treated as a positive scalar value in orbital mechanics. The propellant needed to change your velocity by (say) 3 km/s is independent of whether you're speeding up, slowing down, or changing direction. So, while velocity is a vector quantity with direction and magnitude, delta-v is usually treated as a simple positive-valued scalar. (At least when the impulse comes from a high-thrust rocket engine; for very low thrust things like ion engines, or weird things like solar sails, the problem changes somewhat.)
Personally, my complaint isn't that wikia search sucks. I'm sure it does, but it's alpha. I think the concept is interesting, so I'll reserve judgement for a while.
My complaint is that Wikipedia has major flaws, mostly related to management and editing and such. It desperately needs help. I won't go into detail, everyone has heard the complaints before. My biggest complaint about Wikia search is twofold: Jimbo should be working to fix Wikipedia instead, and more importantly, I see no reason to believe Wikia search won't have all the same problems as Wikipedia all over again.
The reason I care is simply that I think Wikipedia is absolutely amazing, in spite of its (major) flaws. Please, please work on improving it. Wikipedia finally has enough good content, enough recognition, that it has become important to our society. I don't want to see it languish and fail because people went off chasing new neat ideas as soon as the problems with Wikipedia got difficult.
No recursing.
If you want to play that semantic game, no entropy sink is renewable. Call it renewable or sustainable or whatever, it's semantically useful to make the distinction between the category including coal and oil and the category including solar, hydro, etc.