Not it doesn't. Alice can't differentiate between Bob reading the message and an attacker performing a MITM attack.
If that were all it did, it would still be valuable, as it's harder to hide a device that can do that than it is to hide a simple tap. But that's not true - that's the "quantum" part.
Alice sends Bob a photon polarized along a basis randomly chosen by Alice. Bob measures the polarization along a randomly chosen basis. If the bases were the same, one bit was successfully sent, if not it's noise (polarization as measured "up-down" gives no information at all about what you would have measured "left-right", and you can only ever measure one of them, you can't possibly measure both.) After the message is sent, Alice tells Bob (non-secretly) what the basis for every photon was, and the discard all the bits where they didn't randomly line up. The bits where they did randomly agree are the message - the key in this case.
Eve, our eavesdropper, can measure the polarization along some basis, sure, but can't know what basis Alice chose, so the best Eve can do is emit a photon polarized the same say as measured with Eve's basis. If Eve receives all of Alice's photons, and sends photons to Bob, she can only get the transmission right half the time - the chance of guessing right (and thus being undetected) is the same as the chance of guessing the key in the first place.
Well, "quantum crypto" should really be called "quantum key distribution". It's the key distribution part that's "unbreakable" - the rest is just AES or whatever. However, key management is the interesting part of cryptography for attackers: it's easier to somehow find the key than to attack the math.
And the quantum aspect doesn't actually prevent an attacker from snooping during key distribution, but it does provably let you discover that snooping has happened, and act accordingly, which is a valuable thing. (Tapping fiber-optic lines is really easy - not sure why people think it's hard: you just bend the line tight enough for some light to escape, or connect a tap with the same impedance as the line, or whatever.)
Sure, but by that point you're doing computation, not learning the principle involved. Few people find doing computation to be the fun or interesting part of math, which is why we automate it. Doing enough exercises to be good at it, like memorizing multiplication tables, is worthwhile eventually, but it's a terrible place to start.
Ahh. I have the answer to that one! The answer is the same as "why does e^(pi * i) = -1", in a very non-obvious way, but it's very simple.
Why is the derivative of e^x = e^x? Because that's what makes e special - we picked 'e' to make that true. if you look at exponential curves for various bases, it becomes clear that somewhere between 2 and 3 this neat thing happens, and it turns out to be quite handy. If you play around with a graphing calculator it becomes obvious that it must be true for some number, and you can observe/discover "oh, that's e - so that's why its called the natural log".
Why is the derivative of sin(x) equal to cos(x)? Because we use radians. If you measure angles in degrees or grads or whatever, it doesn't work out this way. But if you study simple harmonic motion (which back in the days if record players everyone did), or just think about a point moving around a circle as viewed edge-on, it you will observe/discover that there's this neat property something moving that way: it's velocity as seen edge on is the same as it's position as seen edge on, rotated 90 degrees.. This is really visually obvious with a toothpick stuck to the outside of the spinning platter of a record player!
Once you grok that visually, then clearly there must be some way of measuring angles such that the derivative of sin(x) is cos(x), because that's what those functions mean: the position as viewed from the side, and the position as viewed from the side after rotating 90 degrees! It just so happens that choosing the range [0 2pi) for angles makes the math work out properly. Proving why it's 2pi and not some other value, like proving why it's e and not some other value, is a mess, but you can just observe that some such value must exist for both cases.
Calculus, taught properly, is incredibly easy and intuitive because it's all geometry - you can teach it visually, with no numbers.
Area under a curve? No harder to understand qualitatively than the area of any other shape. Slope of a curve at a point? Again, quite easy to understand with construction paper cut-outs of curves, and a ruler.
And there are plenty of real physics problems that can be solved with simple geometry! Make a drawing of velocity over time that tells a story of a trip. With constant acceleration, all the shapes will be triangles and rectangles. Find the area to find the distance travelled.
For actual curves, you can make them from wood and weigh them to find the integral. Awesome hands-on fun that completely de-mystifies calculus. Not sure a kid would be ready for it by 5, but 8-10, no problem.
I'm guessing the margins on the cell phone business were pretty good there for a while.
As much as I'd love a retail store where I could buy hobby components, and I'd be willing to pay more than internet prices for the immediacy. Heck, for an individual resistor or whatever, I'd pay double. But I don't think there's enough business there, sadly.
Not the OP, but I've long advocated the same stance. I'm pretty much OK with all the money spent that's neither Defense nor transfer payments. Sure, I think a lot of it is wasteful or even harmful, but hey, that's democracy for you. Overall only 20% or so of the budget goes to infrastructure and funding cowboy poetry and whatever, and it's not worth sweating.
The military is being gutted. We'll probable go to far and our grandchildren will regret it, as China and Russia but still show territorial ambitions, but hey, from a budget perspective, it's certainly going down fast.
Mostly, taxes payments simply become government checks mailed out to people. That's the part I have a problem with. I'm all for retirement planning and charity, but I think the legitimate government role in that is quite small, and those checks don't need to pass through their sticky fingers to get the job done.
Train companies tend to be about as efficient as cable companies, for the same reasons. Still, as the sibling posts have pointed out, it's quite cheap per mile-ton compared to anything but waterborne shipping.
I think perhaps some companies just don't think in terms of rail. I wonder if the Tesla plant is using much rail yet - when it was the NUMMI plant there were a couple of freight trains a day, but then volume was far higher.
Trains are still used for long haul of bulk freight. The raw materials for manufacturing generally move from production to consumption over rail (when it's across land), as that's a fairly small network compared to distribution of manufactured goods. In terms of tons of freight moved, rail is still important.
What's curious is the low use of rail from manufacturing to distribution hubs. It is used some, and most of the FedEx/UPs/etc hubs that's I've been to are on rail spurs, but you'd think there'd be more rail used there, or for cross shipping between Amazon distribution centers, or in general "rail to distribution hub" use.
There's plenty of rail right-of-way into and around most big cities, even if the tracks aren't used much: the hard problem was getting the contiguous path to someplace interesting.
"San Franciso" as "civil society" is the best joke I've read all week.
There's really two cases here. One is in, well, ghettos, where often you're pretty safe if you obviously don't belong there, though there's always some risk, but acting provocatively is really asking for trouble. The other is in a C&W bar ("We have both kinds of music") or it's moral equivalent where rural working-class guys are hanging out, drinking. For reasons I don't quite understand, there's a very photography-adverse subculture there. Violence is fairly rare even in dive bars, but there are C&W bars where there's blood on the floor every night. Some people just really enjoy fighting, though it rarely escalates beyond fists.
Lucky me, I've been attacked by both crowds. I don't recommend it as a hobby.
Are you doing this in very public areas, like store fronts and busy streets? Not a problem. But more private spaces, where people hang out (indoors or out), which may just be less travelled public streets, was the problem. Areas, though public, that were regarded as territory to be defended. Of course, any stranger simply walking through such places would likely be hassled.
Where I grew up, taking pictures of strangers anywhere was taking your life in your hands. Some small subset of people won't tolerate that, and that same subset has violence as its first choice for resolving any dispute. Maybe things are different in sheltered yuppie enclaves, and that's fine and all, but when you leave that enclave, be ready for a more diverse world.
American Immigration, legal and otherwise, barely exceeds break even for overall population growth. As the native-born aren't often having more than 2 kids, we can't hold the country together long term without significant immigration of some sort (our biggest government programs would collapse under a shrinking population).
That being the case, can we please make immigration easier for college-educated professionals to legally immigrate than unskilled workers?
There are apparently some real obstacles remaining before you get into the field. Guidance counselors and faculty advisors steering women away from hard technical fields. Man, I hate the "soft bigotry of low expectations".
I trust Bitcoin to hold some value as much as I trust Magic the Gathering cards to (poor MtGoX). Which is to say: more than 0. As long as people are interested, they'll have value, and neither was a passing fad. But I do expect the value to drop a bunch, to where mining may no longer be practical only for new bitcoins. How will bitcoin do when transaction fees become a real thing (if still small)?
I've never regularly worked a 60+ hour week - that's exploitation, not programming. I can think of just a few such weeks in my whole career, times when I had dropped the ball and needed to bust my ass out of simple professionalism.
These day's it's just as common for men as women in the field to have "hard stops" for when they must leave the office - one parent "drops off", the other "picks up" and the latter, male or female, is gone by 5 unless something is actually on fire. Every place I've worked for the past 10 years has respected that.
I think there was a historical shortage because more men than women were willing to be social outcasts, as was once more-or-less required to learn programming. But thankfully society has changed, and for whatever reason I'm seeing women interviewing for entry-level programming positions who are there out of sheer geeky interest, drawn into coding from robotics or EE or similar non-CS backgrounds. Never seen that before, and it's a great sign.
There are bad neighborhoods in tech that have quite the fratboy mentality and are quite hostile to women. You may have heard of "brogramming". I've heard enough first-hand accounts to believe that corner of the profession exists.
But in the sort of work I do - infrastructure and backend stuff - I've never seen a hint of it. We welcome anyone who's a competent coder and who actually wants to write the sort of programs that don't have UIs. It's a fairly introverted and inoffensive bunch even by developer standards, so it's not like "inappropriate comments" are likely regardless.
The one good thing that could come from the current immigration debate is the end of the H1-B program. If we give an easy path for unskilled labor, surely we can use it for college professionals and jettison H1-B!
Yup, it's less than idea, but DNT is free and I bought some adblock solution cheap that seems to work OK (it's free for some limited number of ads blocked, so I use it on infrequently-used VMs).
I find Chrome a consistently crappy user experience, so ewww. FF seems just fine to me, can't quite pinpoint why Chrome annoys me so.
Well, for your first job, set you pride aside and take what you can find. It's hard to break into any industry, and you have to pay for the training you didn't get in school somehow. It will surely pay better than complaining how hard it is to find a job.
But I had the same problem finding people in companies that paid new college hires ridiculously well.
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Not it doesn't. Alice can't differentiate between Bob reading the message and an attacker performing a MITM attack.
If that were all it did, it would still be valuable, as it's harder to hide a device that can do that than it is to hide a simple tap. But that's not true - that's the "quantum" part.
Alice sends Bob a photon polarized along a basis randomly chosen by Alice. Bob measures the polarization along a randomly chosen basis. If the bases were the same, one bit was successfully sent, if not it's noise (polarization as measured "up-down" gives no information at all about what you would have measured "left-right", and you can only ever measure one of them, you can't possibly measure both.) After the message is sent, Alice tells Bob (non-secretly) what the basis for every photon was, and the discard all the bits where they didn't randomly line up. The bits where they did randomly agree are the message - the key in this case.
Eve, our eavesdropper, can measure the polarization along some basis, sure, but can't know what basis Alice chose, so the best Eve can do is emit a photon polarized the same say as measured with Eve's basis. If Eve receives all of Alice's photons, and sends photons to Bob, she can only get the transmission right half the time - the chance of guessing right (and thus being undetected) is the same as the chance of guessing the key in the first place.
Well, "quantum crypto" should really be called "quantum key distribution". It's the key distribution part that's "unbreakable" - the rest is just AES or whatever. However, key management is the interesting part of cryptography for attackers: it's easier to somehow find the key than to attack the math.
And the quantum aspect doesn't actually prevent an attacker from snooping during key distribution, but it does provably let you discover that snooping has happened, and act accordingly, which is a valuable thing. (Tapping fiber-optic lines is really easy - not sure why people think it's hard: you just bend the line tight enough for some light to escape, or connect a tap with the same impedance as the line, or whatever.)
Sure, but by that point you're doing computation, not learning the principle involved. Few people find doing computation to be the fun or interesting part of math, which is why we automate it. Doing enough exercises to be good at it, like memorizing multiplication tables, is worthwhile eventually, but it's a terrible place to start.
Ahh. I have the answer to that one! The answer is the same as "why does e^(pi * i) = -1", in a very non-obvious way, but it's very simple.
Why is the derivative of e^x = e^x? Because that's what makes e special - we picked 'e' to make that true. if you look at exponential curves for various bases, it becomes clear that somewhere between 2 and 3 this neat thing happens, and it turns out to be quite handy. If you play around with a graphing calculator it becomes obvious that it must be true for some number, and you can observe/discover "oh, that's e - so that's why its called the natural log".
Why is the derivative of sin(x) equal to cos(x)? Because we use radians. If you measure angles in degrees or grads or whatever, it doesn't work out this way. But if you study simple harmonic motion (which back in the days if record players everyone did), or just think about a point moving around a circle as viewed edge-on, it you will observe/discover that there's this neat property something moving that way: it's velocity as seen edge on is the same as it's position as seen edge on, rotated 90 degrees.. This is really visually obvious with a toothpick stuck to the outside of the spinning platter of a record player!
Once you grok that visually, then clearly there must be some way of measuring angles such that the derivative of sin(x) is cos(x), because that's what those functions mean: the position as viewed from the side, and the position as viewed from the side after rotating 90 degrees! It just so happens that choosing the range [0 2pi) for angles makes the math work out properly. Proving why it's 2pi and not some other value, like proving why it's e and not some other value, is a mess, but you can just observe that some such value must exist for both cases.
Calculus, taught properly, is incredibly easy and intuitive because it's all geometry - you can teach it visually, with no numbers.
Area under a curve? No harder to understand qualitatively than the area of any other shape. Slope of a curve at a point? Again, quite easy to understand with construction paper cut-outs of curves, and a ruler.
And there are plenty of real physics problems that can be solved with simple geometry! Make a drawing of velocity over time that tells a story of a trip. With constant acceleration, all the shapes will be triangles and rectangles. Find the area to find the distance travelled.
For actual curves, you can make them from wood and weigh them to find the integral. Awesome hands-on fun that completely de-mystifies calculus. Not sure a kid would be ready for it by 5, but 8-10, no problem.
I'm guessing the margins on the cell phone business were pretty good there for a while.
As much as I'd love a retail store where I could buy hobby components, and I'd be willing to pay more than internet prices for the immediacy. Heck, for an individual resistor or whatever, I'd pay double. But I don't think there's enough business there, sadly.
Not the OP, but I've long advocated the same stance. I'm pretty much OK with all the money spent that's neither Defense nor transfer payments. Sure, I think a lot of it is wasteful or even harmful, but hey, that's democracy for you. Overall only 20% or so of the budget goes to infrastructure and funding cowboy poetry and whatever, and it's not worth sweating.
The military is being gutted. We'll probable go to far and our grandchildren will regret it, as China and Russia but still show territorial ambitions, but hey, from a budget perspective, it's certainly going down fast.
Mostly, taxes payments simply become government checks mailed out to people. That's the part I have a problem with. I'm all for retirement planning and charity, but I think the legitimate government role in that is quite small, and those checks don't need to pass through their sticky fingers to get the job done.
Train companies tend to be about as efficient as cable companies, for the same reasons. Still, as the sibling posts have pointed out, it's quite cheap per mile-ton compared to anything but waterborne shipping.
I think perhaps some companies just don't think in terms of rail. I wonder if the Tesla plant is using much rail yet - when it was the NUMMI plant there were a couple of freight trains a day, but then volume was far higher.
Trains are still used for long haul of bulk freight. The raw materials for manufacturing generally move from production to consumption over rail (when it's across land), as that's a fairly small network compared to distribution of manufactured goods. In terms of tons of freight moved, rail is still important.
What's curious is the low use of rail from manufacturing to distribution hubs. It is used some, and most of the FedEx/UPs/etc hubs that's I've been to are on rail spurs, but you'd think there'd be more rail used there, or for cross shipping between Amazon distribution centers, or in general "rail to distribution hub" use.
There's plenty of rail right-of-way into and around most big cities, even if the tracks aren't used much: the hard problem was getting the contiguous path to someplace interesting.
BTW, if your cat is really an IEEE member, that is made of win and awesome.
Meh, I'e had a successful career without college. It's a bitch finding that first professional job, but after that college really stops mattering.
There is no "strong steganography", but if "not drawing attention" is the goal, that's probably your best bet.
"San Franciso" as "civil society" is the best joke I've read all week.
There's really two cases here. One is in, well, ghettos, where often you're pretty safe if you obviously don't belong there, though there's always some risk, but acting provocatively is really asking for trouble. The other is in a C&W bar ("We have both kinds of music") or it's moral equivalent where rural working-class guys are hanging out, drinking. For reasons I don't quite understand, there's a very photography-adverse subculture there. Violence is fairly rare even in dive bars, but there are C&W bars where there's blood on the floor every night. Some people just really enjoy fighting, though it rarely escalates beyond fists.
Lucky me, I've been attacked by both crowds. I don't recommend it as a hobby.
Are you doing this in very public areas, like store fronts and busy streets? Not a problem. But more private spaces, where people hang out (indoors or out), which may just be less travelled public streets, was the problem. Areas, though public, that were regarded as territory to be defended. Of course, any stranger simply walking through such places would likely be hassled.
Where I grew up, taking pictures of strangers anywhere was taking your life in your hands. Some small subset of people won't tolerate that, and that same subset has violence as its first choice for resolving any dispute. Maybe things are different in sheltered yuppie enclaves, and that's fine and all, but when you leave that enclave, be ready for a more diverse world.
Nice - Notgeld is pretty cool. I guess most were actually printed for collectors, and so were made to be interesting.
American Immigration, legal and otherwise, barely exceeds break even for overall population growth. As the native-born aren't often having more than 2 kids, we can't hold the country together long term without significant immigration of some sort (our biggest government programs would collapse under a shrinking population).
That being the case, can we please make immigration easier for college-educated professionals to legally immigrate than unskilled workers?
There are apparently some real obstacles remaining before you get into the field. Guidance counselors and faculty advisors steering women away from hard technical fields. Man, I hate the "soft bigotry of low expectations".
I trust Bitcoin to hold some value as much as I trust Magic the Gathering cards to (poor MtGoX). Which is to say: more than 0. As long as people are interested, they'll have value, and neither was a passing fad. But I do expect the value to drop a bunch, to where mining may no longer be practical only for new bitcoins. How will bitcoin do when transaction fees become a real thing (if still small)?
I've never regularly worked a 60+ hour week - that's exploitation, not programming. I can think of just a few such weeks in my whole career, times when I had dropped the ball and needed to bust my ass out of simple professionalism.
These day's it's just as common for men as women in the field to have "hard stops" for when they must leave the office - one parent "drops off", the other "picks up" and the latter, male or female, is gone by 5 unless something is actually on fire. Every place I've worked for the past 10 years has respected that.
I think there was a historical shortage because more men than women were willing to be social outcasts, as was once more-or-less required to learn programming. But thankfully society has changed, and for whatever reason I'm seeing women interviewing for entry-level programming positions who are there out of sheer geeky interest, drawn into coding from robotics or EE or similar non-CS backgrounds. Never seen that before, and it's a great sign.
To be sure, we need more nurses far more than we need more programmers. It's a serious crises in some areas.
There are bad neighborhoods in tech that have quite the fratboy mentality and are quite hostile to women. You may have heard of "brogramming". I've heard enough first-hand accounts to believe that corner of the profession exists.
But in the sort of work I do - infrastructure and backend stuff - I've never seen a hint of it. We welcome anyone who's a competent coder and who actually wants to write the sort of programs that don't have UIs. It's a fairly introverted and inoffensive bunch even by developer standards, so it's not like "inappropriate comments" are likely regardless.
The one good thing that could come from the current immigration debate is the end of the H1-B program. If we give an easy path for unskilled labor, surely we can use it for college professionals and jettison H1-B!
Yup, it's less than idea, but DNT is free and I bought some adblock solution cheap that seems to work OK (it's free for some limited number of ads blocked, so I use it on infrequently-used VMs).
I find Chrome a consistently crappy user experience, so ewww. FF seems just fine to me, can't quite pinpoint why Chrome annoys me so.
Well, for your first job, set you pride aside and take what you can find. It's hard to break into any industry, and you have to pay for the training you didn't get in school somehow. It will surely pay better than complaining how hard it is to find a job.
But I had the same problem finding people in companies that paid new college hires ridiculously well.