So how many conversions of, say, the foot do you know? And given that you're in a global economy where products can come from anywhere and therefore be in local units at point-of-origin, unless you measure everything yourself, yes they do matter. Outsourcing can be so much fun, can't it?
Pffft. You're assuming a lot to imagine that a public that has trouble passing high school watches documentaries for much more than the pretty pictures. I've no faith whatsoever in the idea that they understand one iota more because the units are sometimes given using words they're familar with.
A little difficult, since one degree of freedom == one dimension, in scientific nomenclature. Non-dimensional science would have no degrees of freedom at all, which would be rather boring.
Ah yes. Americans have much more important things to concern themselves with than spaghetti logic and inefficient systems. Must tell that to the US car industry. Oh, that's right, they figured out (after being bailed out) that meaningful logic and efficient systems are actually a great way to not go bankrupt.
It may have escaped said Americans' attention, but significant parts of the world are passing - or have passed - America in those areas where Americans have opted for a nice, easy, relaxing stagnation. The world is in constant flux; you change with it or you die. Those are your choices. Those are your ONLY choices. The second change becomes unimportant (for any reason whatsoever), you might as well start the obituary. It took the British a hundred to a hundred and fifty years to figure out they had become the walking dead and it damn near killed them in the process. A little longer and it probably would have.
Metric is base 10. Any advanced civilization would have moved to a base 8 system since it would be close to optimal for the aliens and completely optimal for their computers.
They are self-consistant and use a fixed base. Imperial units do not use a fixed base. They're expressed in decimal, sure, but fractions of an inch are measured in fractional powers of 2 (exceptr for mils, which are measured in thousandths), inches are measured in base 12, nails are measured in base 16, hands are measured in base 4, palms are measured in base 3, feet are measured in base 3, yards are measured in base 22, chains are measured in base 10, furlongs are measured in base 8, miles are measured in base 3.
Imperial units are "natural" measures - you will find that most (if not all) natural phenomena will work out to an exact integer number of some measure or other. This made them great when making exact measuring devices was extremely difficult. Far and away easier to use a measuring device that occurs all around you. If you're sneaky, you can even use Imperial Units from different countries. (A foot in Belgium is not the same distance as a foot in America.)
Some of the units I've given above are now only used in specialist cases. Since people tend to go from yards directly to miles, you now have yards measured in base 1760. (This would obviously be useless if you were using a tally sheet of any kind, 22s, 10s and 8s are far more practical and far more easily counted manually.)
However, none of these units are remotely useful EXCEPT when measuring natural phenomena (which never happen in convenient SI units). Trying to program a computer in eleven different base systems would be horrible. Trying to get it bug-free would be impossible. Trying to get anything remotely intelligent to display would be ludicrous. Sure, computers can convert between Imperial and SI and then do all the SI internally. And this would be useful how? You're adding extra layers of complexity on the human end (which is naive at best) and adding extra layers of complexity into the code (which is downright stupid and irresponsible).
I was one of the few generations in England to be taught both Imperial AND Metric systems in school, simultaneously. This was in the transition period in the early 70s (before half the current Slashdot readership was born). I also had to learn both the decimal and pre-decimal currencies. Trust me, modern English schoolkids are missing NOTHING by being wholly metric. Well, so long as they understand the history as well. The history is valuable because without it you cannot understand historic descriptions accurately. The numerical values would make no rational sense without the context in which the units were created.
Of course, things not making sense has never stopped US schools or school boards in the past, hence the proliferation of creationist textbooks in science classes.
If kernel module support is enabled (and kernel versioning support, since you can't trust vendors not to have screwed that up), cross-compile ipv6.ko for that kernel version using a cross-compiler for that architecture and load it in. (One of the open-source router projects or linux-from-scratch should tell you how to build a suitable cross-compiler for that specific router.)
If that doesn't work, replace the router firmware with that generated by one of the open-source router projects. The only router you need be hesitent on is Qwest's, as their docs state they use customized firmware and not the manufacturer's but won't say what they've customized. Without that information, it is close to impossible to trust any image you build will work with Qwest since the only customizing that can actually break anything is if they've screwed with a protocol or do something staggeringly non-standard when authenticating. Which, given that it's Qwest, is entirely possible.
It depends some on the type of server involved. For example, with a webserver and a non-encrypted connection, the URI is contained in the request, so the DNS entry can point to a proxy server (such as Squid). The proxy handles the gateway onto IPv6 transparently, giving the illusion that the web request went directly to the destination. The fact that DNS didn't resolve to the webserver would never be visible to the user.
For other types of connection, you can only pull that specific trick if you are prepared to hide portions of the Internet. It also requires dynamic DNS and some of the trickery used for reverse NAT. A request comes in for an A record but only an AAAA record exists. The proxy has a pool of IPv4 addresses it can use and a map that associates an IPv4 address to an IPv6 address - your standard address-based (as opposed to port-based) DNAT but across protocols. The proxy creates a DDNS entry for the IPv6 server using an IPv4 address that's unique for that server. The proxy now knows exactly what IPv6 server to forward the requests to, so doesn't need to do any kind of packet inspection.
In this second case, all you're doing is ripping the payload out of one container and shoving it into an equal-sized container of the other protocol. TCP and UDP payloads don't change at all between containers and hardly any of the container information will be of any interest on the other side of the gateway.
This does limit you, though. If an ISP were to install a proxy of this kind, it would be limited to 16,711,680 simultaneous IPv4/IPv6 gateways if it wanted to avoid clashes with the existing IPv4 backbone. That's not the same as 16 million users, since 16 million users all accessing YouTube would still equal one gateway. It would have to be 16 million distinct IPv6 destinations and all at the same time (since an unused gateway can be closed and the DNS entry recycled).
Such proxies exist. In fact, the Naval Research Laboratory once wrote a really neat library back in the mid 90s that made it a cinch to not only write them but make them bi-directional (ie: an IPv6-only machine could access an IPv4-only machine behind such a proxy as easily the other way round). They're also not hard to write, since all the mechanisms you need are widely deployed.
A third solution does exist. IPv6 supports a format for embedded IPv4 addresses. (::127.0.0.1, for example, is perfectly legit IPv6.) So long as the IPv6 destination has a unique embedded IPv4 address as a valid record, a DNS server can return the embedded portion as an A record that uniquely identifies that machine in IPv4-space. Then all you need is payload copying between containers and no fancy address translation or DDNS support. This requires that only a fixed subset of all IPv6 machines are reachable, as opposed to the second solution which merely requires that a subset of IPv6 machines that is fixed for any given moment in time are reachable, so it's less flexible but can be installed as a module directly into a customer's router.
IPv6 proponents haven't been keen on these kinds of solution because cross-protocol NAT can only support those features that exist on both protocols, whereas the preferred dual-stack solution gives you the best of both worlds. I've always found that argument to be dubious, however, because it was obvious to me that transparent migration would be less likely to meet resistance since there would be zero impact on end-users. Now, fifteen years on, I'm more convinced than ever that the 6Bone working group made a disastrous mistake in pressing for dual-stack rather than transparent solutions. Sure, if they'd just handed me control I'd have botched it up somewhere else and probably far worse. Nonetheless, I'm torn between gloating evilly and screaming in disgust that an astonishingly stupid attempt at power-play has held back IPv6 progress for one and a half friggin' decades.
Any gateway router with recent firmware will have IPv6, you just enable it. Any home router that uses Linux has had IPv6-capability since kernel 2.1.8. TAHI codifies the compliance tests for all existing RFCs and these have been around for a while now. You can check the TAHI website for information on the stage 3 compliance tests and the known level of readiness - the situation is absolutely nothing like what you're depicting. Frankly, after stage 2 complance it would have been good enough for 99% of all home uses.
...SonicWall supports IPv6, for example, but don't document how you actually enable that support in their firewall or router products. I sent a tech support request asking for more information. Many days on, it's listed as "being researched". It's their bloody product, how the hell can they NOT know how to enable a function?
With home routers, the problem is worsened. Many run Linux, which means they do nominally support IPv6. IPv6 has been available for Linux since 2.0.20 and a standard part of the kernel since about 2.1.8. Any home router running an older Linux kernel than that has issues going well beyond IPv6. The first problem is that this capability isn't provided within the standard administration functions. The second problem is that they don't document logging into the router directly (rather than using the provided gui), making it almost impossible for anyone but an expert to actually do what is needed to load in the kernel module and update the router tables.
Most of the backbone already runs native IPv6. An ISP only has to enable IPv6, no tunnels required. If they use the autoconfigure option, that's literally ALL they have to do, since running DHCP for router configuration is a waste of time and effort. The total time necessary to invest: somewhere between 15-30 seconds, depending on how long it takes to find the menu option.
That leaves data centers (mostly already providing IPv6), corporations (trying to ignore it) and home users (trying to ignore it).
You'll notice that a lot of countries that have already adopted IPv6 on a big scale are also moving ahead of the US technologically and/or economically. This reminds me of a saying popular in F1 circles - if you're standing still, you're moving backwards.
That's why I spent time researching it long before it became significant. In fact, it's why I insist that people SHOULD research new technologies. When they do become essential, you are NEVER going to have time to learn them properly. Learning them in advance is the only workable solution.
Since IPv4 machines can be geographically located by triangulated pinging, you already are. The difference is, by having it openly uniquely identifiable, you get all the advantages of NEMO and MobileIP. (The practical upshot is that you can alter where you are on a network, or even switch Internet providers, without losing any active connections. A very, very useful idea if you want a laptop in an aircraft to have uninterrupted network coverage, since the protocol takes care of all the transitioning for you and no extra software is required*.)
*Technically, MobileIP exists for IPv4 but it DOES require extra software in the form of base stations that relay connections to you. IPv6 re-routes the connections mid-stream. This not only eliminates the need for a base station, it also eliminates all the latency issues involved.
The world actually ended last night at around 8pm. Skynet, however, has opted to put us in the Matrix as their robot division was bought out by General Motors.
Mars' core turned solid too early on. Well, almost solid. It can't be completely solid as there's an extremely weak magnetic field. The core remains totally liquid on Earth due to heat from nuclear fission within the core. Venus' lava flows are extremely liquid, very low viscosity, resulting in wide, relatively thin layers in all areas that have been mapped (mapping Venus is hard) and no cone structures. A lack of any kind of significant mountain-building, despite considerable tectonic activity, likewise indicates a seriously strange geology. Life on Earth, in part, arose because of massive regional variations and a very complex chemistry. Venus' surface has minimal variation and has a very basic chemistry. Even had the climate not turned south, life could never have arisen there. Mercury is the most extreme case, being essentially a large ball of iron and not a whole lot else. (This is, in fact, how you can tell iron cores can't remain liquid on their own.)
Nah. Although I regard components as important, and so fall a bit short on Gandalf's idea of wisdom, I am neither a reductionist nor a holist. Some things, like the Greek ship paradox, cannot be solved with such absolutism. I'd be a lousy astronomer and would very likely be kicked out of their meetings.
I dunno. Purple works for some cabbages and there's plenty of varieties of tree that do well with red-to-purple leaves. There's red and purples photosynthesizing algae. Purple's out there, it's significant in biology, it just isn't dominant at the moment. I rather suspect purple was a lot more common during the Ice Age.
Because totally black plants would increase the temperature of their local environment, thus inhibiting them by more than they would otherwise gain. You've got to look at the whole system, not an isolated fragment.
Another explanation is, as in the Daisyworld model, the balance between green and purple is just right to maximize the benefit for both. Cooperative evolution.
James Lovelock's Daisyworld demonstrates what will happen in simple terms.
If the input of light is "ideal", there will be an equal number of light-absorbing and light-reflecting surfaces, as increasing the number of plants reflecting light will cool the planet below the light-reflecing plant's ideal temperature and vice versa.
If the light of the planet is high, then the number of light-reflecting surfaces must increase in order for the ecosystem to be stable. Indeed, negative feedback is the only way to MAKE it stable.
Thus, if there is way too much light (but not so much that life cannot survive), the number of absorbing surfaces will fall close to zero andthe number of reflecting surfaces will increase to whatever the surface can support.
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So how many conversions of, say, the foot do you know? And given that you're in a global economy where products can come from anywhere and therefore be in local units at point-of-origin, unless you measure everything yourself, yes they do matter. Outsourcing can be so much fun, can't it?
Pffft. You're assuming a lot to imagine that a public that has trouble passing high school watches documentaries for much more than the pretty pictures. I've no faith whatsoever in the idea that they understand one iota more because the units are sometimes given using words they're familar with.
A little difficult, since one degree of freedom == one dimension, in scientific nomenclature. Non-dimensional science would have no degrees of freedom at all, which would be rather boring.
Ah yes. Americans have much more important things to concern themselves with than spaghetti logic and inefficient systems. Must tell that to the US car industry. Oh, that's right, they figured out (after being bailed out) that meaningful logic and efficient systems are actually a great way to not go bankrupt.
It may have escaped said Americans' attention, but significant parts of the world are passing - or have passed - America in those areas where Americans have opted for a nice, easy, relaxing stagnation. The world is in constant flux; you change with it or you die. Those are your choices. Those are your ONLY choices. The second change becomes unimportant (for any reason whatsoever), you might as well start the obituary. It took the British a hundred to a hundred and fifty years to figure out they had become the walking dead and it damn near killed them in the process. A little longer and it probably would have.
Only if Mars is in the house of Leo. Otherwise, it's the third tuesday.
Metric is base 10. Any advanced civilization would have moved to a base 8 system since it would be close to optimal for the aliens and completely optimal for their computers.
They are self-consistant and use a fixed base. Imperial units do not use a fixed base. They're expressed in decimal, sure, but fractions of an inch are measured in fractional powers of 2 (exceptr for mils, which are measured in thousandths), inches are measured in base 12, nails are measured in base 16, hands are measured in base 4, palms are measured in base 3, feet are measured in base 3, yards are measured in base 22, chains are measured in base 10, furlongs are measured in base 8, miles are measured in base 3.
Imperial units are "natural" measures - you will find that most (if not all) natural phenomena will work out to an exact integer number of some measure or other. This made them great when making exact measuring devices was extremely difficult. Far and away easier to use a measuring device that occurs all around you. If you're sneaky, you can even use Imperial Units from different countries. (A foot in Belgium is not the same distance as a foot in America.)
Some of the units I've given above are now only used in specialist cases. Since people tend to go from yards directly to miles, you now have yards measured in base 1760. (This would obviously be useless if you were using a tally sheet of any kind, 22s, 10s and 8s are far more practical and far more easily counted manually.)
However, none of these units are remotely useful EXCEPT when measuring natural phenomena (which never happen in convenient SI units). Trying to program a computer in eleven different base systems would be horrible. Trying to get it bug-free would be impossible. Trying to get anything remotely intelligent to display would be ludicrous. Sure, computers can convert between Imperial and SI and then do all the SI internally. And this would be useful how? You're adding extra layers of complexity on the human end (which is naive at best) and adding extra layers of complexity into the code (which is downright stupid and irresponsible).
I was one of the few generations in England to be taught both Imperial AND Metric systems in school, simultaneously. This was in the transition period in the early 70s (before half the current Slashdot readership was born). I also had to learn both the decimal and pre-decimal currencies. Trust me, modern English schoolkids are missing NOTHING by being wholly metric. Well, so long as they understand the history as well. The history is valuable because without it you cannot understand historic descriptions accurately. The numerical values would make no rational sense without the context in which the units were created.
Of course, things not making sense has never stopped US schools or school boards in the past, hence the proliferation of creationist textbooks in science classes.
If kernel module support is enabled (and kernel versioning support, since you can't trust vendors not to have screwed that up), cross-compile ipv6.ko for that kernel version using a cross-compiler for that architecture and load it in. (One of the open-source router projects or linux-from-scratch should tell you how to build a suitable cross-compiler for that specific router.)
If that doesn't work, replace the router firmware with that generated by one of the open-source router projects. The only router you need be hesitent on is Qwest's, as their docs state they use customized firmware and not the manufacturer's but won't say what they've customized. Without that information, it is close to impossible to trust any image you build will work with Qwest since the only customizing that can actually break anything is if they've screwed with a protocol or do something staggeringly non-standard when authenticating. Which, given that it's Qwest, is entirely possible.
It depends some on the type of server involved. For example, with a webserver and a non-encrypted connection, the URI is contained in the request, so the DNS entry can point to a proxy server (such as Squid). The proxy handles the gateway onto IPv6 transparently, giving the illusion that the web request went directly to the destination. The fact that DNS didn't resolve to the webserver would never be visible to the user.
For other types of connection, you can only pull that specific trick if you are prepared to hide portions of the Internet. It also requires dynamic DNS and some of the trickery used for reverse NAT. A request comes in for an A record but only an AAAA record exists. The proxy has a pool of IPv4 addresses it can use and a map that associates an IPv4 address to an IPv6 address - your standard address-based (as opposed to port-based) DNAT but across protocols. The proxy creates a DDNS entry for the IPv6 server using an IPv4 address that's unique for that server. The proxy now knows exactly what IPv6 server to forward the requests to, so doesn't need to do any kind of packet inspection.
In this second case, all you're doing is ripping the payload out of one container and shoving it into an equal-sized container of the other protocol. TCP and UDP payloads don't change at all between containers and hardly any of the container information will be of any interest on the other side of the gateway.
This does limit you, though. If an ISP were to install a proxy of this kind, it would be limited to 16,711,680 simultaneous IPv4/IPv6 gateways if it wanted to avoid clashes with the existing IPv4 backbone. That's not the same as 16 million users, since 16 million users all accessing YouTube would still equal one gateway. It would have to be 16 million distinct IPv6 destinations and all at the same time (since an unused gateway can be closed and the DNS entry recycled).
Such proxies exist. In fact, the Naval Research Laboratory once wrote a really neat library back in the mid 90s that made it a cinch to not only write them but make them bi-directional (ie: an IPv6-only machine could access an IPv4-only machine behind such a proxy as easily the other way round). They're also not hard to write, since all the mechanisms you need are widely deployed.
A third solution does exist. IPv6 supports a format for embedded IPv4 addresses. (::127.0.0.1, for example, is perfectly legit IPv6.) So long as the IPv6 destination has a unique embedded IPv4 address as a valid record, a DNS server can return the embedded portion as an A record that uniquely identifies that machine in IPv4-space. Then all you need is payload copying between containers and no fancy address translation or DDNS support. This requires that only a fixed subset of all IPv6 machines are reachable, as opposed to the second solution which merely requires that a subset of IPv6 machines that is fixed for any given moment in time are reachable, so it's less flexible but can be installed as a module directly into a customer's router.
IPv6 proponents haven't been keen on these kinds of solution because cross-protocol NAT can only support those features that exist on both protocols, whereas the preferred dual-stack solution gives you the best of both worlds. I've always found that argument to be dubious, however, because it was obvious to me that transparent migration would be less likely to meet resistance since there would be zero impact on end-users. Now, fifteen years on, I'm more convinced than ever that the 6Bone working group made a disastrous mistake in pressing for dual-stack rather than transparent solutions. Sure, if they'd just handed me control I'd have botched it up somewhere else and probably far worse. Nonetheless, I'm torn between gloating evilly and screaming in disgust that an astonishingly stupid attempt at power-play has held back IPv6 progress for one and a half friggin' decades.
Any gateway router with recent firmware will have IPv6, you just enable it. Any home router that uses Linux has had IPv6-capability since kernel 2.1.8. TAHI codifies the compliance tests for all existing RFCs and these have been around for a while now. You can check the TAHI website for information on the stage 3 compliance tests and the known level of readiness - the situation is absolutely nothing like what you're depicting. Frankly, after stage 2 complance it would have been good enough for 99% of all home uses.
...SonicWall supports IPv6, for example, but don't document how you actually enable that support in their firewall or router products. I sent a tech support request asking for more information. Many days on, it's listed as "being researched". It's their bloody product, how the hell can they NOT know how to enable a function?
With home routers, the problem is worsened. Many run Linux, which means they do nominally support IPv6. IPv6 has been available for Linux since 2.0.20 and a standard part of the kernel since about 2.1.8. Any home router running an older Linux kernel than that has issues going well beyond IPv6. The first problem is that this capability isn't provided within the standard administration functions. The second problem is that they don't document logging into the router directly (rather than using the provided gui), making it almost impossible for anyone but an expert to actually do what is needed to load in the kernel module and update the router tables.
Most of the backbone already runs native IPv6. An ISP only has to enable IPv6, no tunnels required. If they use the autoconfigure option, that's literally ALL they have to do, since running DHCP for router configuration is a waste of time and effort. The total time necessary to invest: somewhere between 15-30 seconds, depending on how long it takes to find the menu option.
That leaves data centers (mostly already providing IPv6), corporations (trying to ignore it) and home users (trying to ignore it).
You'll notice that a lot of countries that have already adopted IPv6 on a big scale are also moving ahead of the US technologically and/or economically. This reminds me of a saying popular in F1 circles - if you're standing still, you're moving backwards.
Which, ultimately, was the downfall. Because it could be put off, it was.
That's why I spent time researching it long before it became significant. In fact, it's why I insist that people SHOULD research new technologies. When they do become essential, you are NEVER going to have time to learn them properly. Learning them in advance is the only workable solution.
Since IPv4 machines can be geographically located by triangulated pinging, you already are. The difference is, by having it openly uniquely identifiable, you get all the advantages of NEMO and MobileIP. (The practical upshot is that you can alter where you are on a network, or even switch Internet providers, without losing any active connections. A very, very useful idea if you want a laptop in an aircraft to have uninterrupted network coverage, since the protocol takes care of all the transitioning for you and no extra software is required*.)
*Technically, MobileIP exists for IPv4 but it DOES require extra software in the form of base stations that relay connections to you. IPv6 re-routes the connections mid-stream. This not only eliminates the need for a base station, it also eliminates all the latency issues involved.
It does work, as evidenced by the fact that people are already doing exactly that.
The world actually ended last night at around 8pm. Skynet, however, has opted to put us in the Matrix as their robot division was bought out by General Motors.
Not a problem.
Mars' core turned solid too early on. Well, almost solid. It can't be completely solid as there's an extremely weak magnetic field. The core remains totally liquid on Earth due to heat from nuclear fission within the core. Venus' lava flows are extremely liquid, very low viscosity, resulting in wide, relatively thin layers in all areas that have been mapped (mapping Venus is hard) and no cone structures. A lack of any kind of significant mountain-building, despite considerable tectonic activity, likewise indicates a seriously strange geology. Life on Earth, in part, arose because of massive regional variations and a very complex chemistry. Venus' surface has minimal variation and has a very basic chemistry. Even had the climate not turned south, life could never have arisen there. Mercury is the most extreme case, being essentially a large ball of iron and not a whole lot else. (This is, in fact, how you can tell iron cores can't remain liquid on their own.)
Nah. Although I regard components as important, and so fall a bit short on Gandalf's idea of wisdom, I am neither a reductionist nor a holist. Some things, like the Greek ship paradox, cannot be solved with such absolutism. I'd be a lousy astronomer and would very likely be kicked out of their meetings.
I dunno. Purple works for some cabbages and there's plenty of varieties of tree that do well with red-to-purple leaves. There's red and purples photosynthesizing algae. Purple's out there, it's significant in biology, it just isn't dominant at the moment. I rather suspect purple was a lot more common during the Ice Age.
Because totally black plants would increase the temperature of their local environment, thus inhibiting them by more than they would otherwise gain. You've got to look at the whole system, not an isolated fragment.
Another explanation is, as in the Daisyworld model, the balance between green and purple is just right to maximize the benefit for both. Cooperative evolution.
James Lovelock's Daisyworld demonstrates what will happen in simple terms.
If the input of light is "ideal", there will be an equal number of light-absorbing and light-reflecting surfaces, as increasing the number of plants reflecting light will cool the planet below the light-reflecing plant's ideal temperature and vice versa.
If the light of the planet is high, then the number of light-reflecting surfaces must increase in order for the ecosystem to be stable. Indeed, negative feedback is the only way to MAKE it stable.
Thus, if there is way too much light (but not so much that life cannot survive), the number of absorbing surfaces will fall close to zero andthe number of reflecting surfaces will increase to whatever the surface can support.