There are B-52s still being built. Admittedly, not using the original design and the only similarity with the original is the name, but they are there.
NASA should be funded in a similar way to the way the BBC is funded in the UK - given a fixed amount for a fixed length of time and a charter for that period of time, with zero interference permitted outside of the GAO verifying that the charter is being complied with to the limits possible given the funding. This hybrid state should have the right to make additional money and should have some of the rights granted to private organizations but not granted to public organizations, but also have some of the protections granted to the civil service.
This is the only way to give it the funding necessary without the political ties that corrupted the Space Shuttle program, leading to an overweight monstrosity.
The Constellation is the official Shuttle replacement. Wasn't there an unofficial replacement being designed (and maybe developed) by ex-NASA guys? That was cheaper, on-schedule and likely to actually work?
The aerospace industry is suffering from a lack of manpower right now. Both Boeing and EADS are failing to deliver. Sane competitors use times like those to their advantage. Foolish competitors sack their workforce instead.
Sure, these workers may not have ideal skills for other programs, but that's a matter of training. They already have skills in technologies that required far higher precision and far higher quality than most other projects would require - those are skills that would take a LONG time to teach. Moving workers onto new projects is efficient, sacking them and training new employees in all the stuff the old ones already knew is inefficient.
Anticipate, keep several steps ahead of the market, never over-specialize your employees, always exploit transferable skills, never waste a single resource, never give your competitor the chance to regain lost ground through ditched employees, a redundant employee is a wasted opportunity.
You are correct, which is why it is all the more important for teachers of subjects such as histories or the humanities clearly distinguish between the two. It is by confusing the objective with the subjective that modern reporters excuse their lack of objectivity by claiming that it's all really subjective anyway. A gun was fired or it wasn't, a bridge was crossed or it wasn't, a battle was fought or it wasn't. These things may be subjectively interpreted, but their objective reality (or lack thereof) is independent of that interpretation.
It is fair enough that some things are not knowable - because records were destroyed, or because there was a concerted effort to conceal that information permanently - but there the fact that is known is that the historical data for a definitive answer does not exist. So there is still a definite split between objective facts and subjective views. In most real-world cases, there will be additional facts - the archaeological facts on the ground. These are "facts" in the sense of object A was found at location B with a context of C and scientific tests reveal D. Because the archaeological record can be tampered with, there is nothing that definitely links object A to a specific event or a specific person. Interpretation of such a record is largely subjective.
Actually, we can refine this two-way split a little further into a three-way split: The facts (insofar as they can be objectively known), the subjective views, and the deductive reasoning/critical thinking that allows you to produce "derivative facts" ("facts" for which no direct evidence exists but which explains both the facts that do exist AND the subjective views as far as can be reasonably done). Derivative facts are not truly objective (as different people may come to different conclusions) but neither are they truly subjective (assuming that the method used is based on the scientific method and has been shown to produce accurate conclusions when tested).
I'd say it depends on who is getting the money. Most sign shops are tiny, have no money to speak of and unreliable workloads.
If these are the sign shops that will be getting New York's money, then there will finally be some stimulus dollars where they need to be. That alone makes it "well spent".
I freely admit that, which is precisely why it scares me whenever anything that might encourage people to look for other views is slammed or eliminated.
People should be exposed to as many different views of historical events as possible, including the archaeological evidence on the ground as well as the subjective opinions of participants. The only time that I can consider restricting this to be acceptable is when someone has already done that legwork and endeavored to produce the most perspective-neutral account possible. I would consider that to be functionally the same as listening to the different views directly - to a degree. It's not possible to capture everything in a single account but critical thinking is not a skill taught in schools and you can't do much with the evidence alone without such a skill.
I give not a damn whether you are left-wing or right-wing, accuracy matters and honesty should come first above and beyond the whims of any faction. In this case, however, the whims come not from the left but from the extreme right. This matters only in that your own post is dishonest and that is no more acceptable than the dishonesty of anyone else.
The difference between history and propaganda is that history is what actually happened, whereas propaganda is what people want to have happened. It is important not to confuse the two. History is rarely taught, because what actually happened is rarely known.
The march through Russia will doubtless have been filled with heroic deeds, not least because of the extreme conditions they faced. Rommel, the commander of the German's African forces, performed many acts of heroism and is often held in high regard by military historians. Rudolph Hess is an interesting figure, not least because he managed to be reviled AND held as a hero by both sides simultaneously. That's no small achievement. A great uncle of mine who helped hold off the German forces whilst the rest of the allies escaped at Dunkirk maintained a diary of the retreat and then of his time as a POW. His description of the German forces shows a full range of people, ranging from the compassionate to the psychotic. His description is a far, far cry from what you'll see in any traditional history book.
Not all history is written by the victors. The Bayoux Tapestry, for example, was produced by the Saxons and depicts the Saxon view of the Battle of Hastings, not the Norman perspective.
Amazingly enough, Prince Charles has actually said a few things over the years that are actually quite smart. The idea that towns will function better if there's a well-defined center is sound. The idea that people prefer buildings to look good, as well as function well, is obvious. In this particular debate, he has been slammed on all sides but again appears to have made some valid points - it is possible to farm economically AND be ecologically sound. The two do not have to be in conflict.
Not sure about the cost-effectiveness of this one-man think-tank, but the topics he has ventured into are generally controversial and the corporations he's been battling are too big for most campaigns to be effective against.
The large amount of US population has been happy to accept the aid of insurgent groups (the various resistance groups in Occupied Europe, for example) when it has been convenient. Indeed, the US was largely liberated from British rule by an insurgency. Unofficial groups that do not operate under the command of a State have existed throughout history and have been utilized by every nation on Earth. Until the Iraqi "Awakening Councils" were accepted by the government there, they too were unofficial militia operating outside of any central command structure. Don't recall hearing too many oppose them in the US.
The reason the Taliban aren't legitimate in the eyes of the US is that the US is fighting them. Everything else is a contrived excuse.
Well, in Japan they apparently teach history and play video games in which they win World War 2. This is highly important to them, but is not a war that is currently going on. I suspect that if EA produced a game in which you were a Vietnamese soldier fighting the Americans, the American public would oppose that as well, even though it's a war that's over, but a game in which you were an American beating the Vietnamese, that would be more likely to pass muster.
It's less about whether the war is going on (that's a feeble excuse), it's about imaginary national shame. If a person has that much shame, they should see a p-doc to deal with it, not censor others so that they can avoid ever having to face up to the fact they've serious issues.
Perhaps those wanting to reduce the reminders should also remove the "Support Our Troops" bumper stickers and every other reminder they voluntarily put up. In fact, aren't the families of those soldiers currently at war responsible for 99% of the reminders that exist? If they started there, they could eliminate almost all of the problem without ever having to go near the game.
In real wars, people die. It is expected. All who go into a warzone do so in the knowledge that they may not return. How do you sacrifice that which you have already surrendered for King/Queen/President/Fanatic (delete according to nation) and Country?
Should the Americans get their name removed? There will be friends and family of the Taliban too. If this were truly about honoring the fallen, why be selective?
Should they retroactively delete the names of nations for World War 2 games? All of those nations had people die too, and friends and family of those fallen are still alive today.
Of course they shouldn't. The reality is that wargames depict a historical context and history doesn't change to suit the likes of one group or another. There is only one history, the events that took place.
Further, we learn from history that it is dangerous to make an enemy faceless. Doing so is the number one cause of wartime atrocities. What these pressure groups have basically said is that it is more important to hide the reality of the situation than it is to keep Americans aware that they are fighting against people with lives and beliefs of their own. This is a dangerous attitude to have.
I cannot blame a company for eventually caving under pressure, especially one as small as this. But frankly this whitewashing of history is disturbing and historically the consequences of such acts have never been good. This is extremely bad juju.
Since his position was not that we'd actually have a theory of anything (read through my post again) but rather would discover something new that would force us to abandon our prior notion of what a unified theory would be, he has NOT revised his position but actually demonstrated what he set out to demonstrate.
If you do not understand this, I will write out what he said in pseudo-code:
I would say that assassination in general is a bad thing, no matter who does it or who to. For example, whilst I have some sympathy for the UK government at the time, assassinating three suspects in Gibraltar was not something I would consider legitimate. The problem was real, but that doesn't make the solution right.
I cannot think of a single assassination in history that has done anything other than create a hero out of the victim and produce the opposite of the intended result. There may be exceptions, but so very few of them in the scheme of things that you can effectively conclude that the world would be better from outlawing such practices. Utterly. (And I mean utterly. A President guilty of such an act should have no claim to sovereign immunity. If the ICJ has strong evidence of such a crime by such a person, they should have the right to prosecute and to hell with whether the nation is signed up or not.)
The brain grows in teenage years, this tails off in the mid 20s, then dies back where it is under-utilized. The insulation around the axons starts thinning around the age of 40, leading to accelerated degradation. This is why 22-32 is the time you're most likely to do anything interesting. It's when your brain is at maximum and you've the knowledge to make use of it. Though better teaching may give people the knowledge needed to do significant work at a younger age.
Since antidepressants and other drugs can stimulate brain growth, it is possible that you can hold off the die-back. If you learn multiple languages, the mental requirements appear to be great enough that you can prevent the brain from contracting as much. Currently, most of the evidence is circumstantial (people from the Age of Enlightenment often knew 4-8 languages and were able to produce constructive work at an advanced age), but since recent studies on depression show that seratonin levels are not as important as brain growth and the happiest nations are invariably the ones where multiple languages are taught, there is some basis for thinking that brain growth is absolutely tied to brain function.
If this is correct, then scientists who are over-specialized (and therefore do not use the full capacity of the brain but merely those aspects of the brain useful to their specialty) will stop contributing at an earlier age. If a scientist wishes to contribute for longer, they must stretch more of their brain more of the time. Further, education must be revamped to promote this. Brain-dead education will produce brain-dead people. Slowing deterioration at that point is worthless, and nothing can be done to boost a brain that isn't there. If you push the 9-18 age bracket to the absolute limit, they can filter out what they don't need/want later. But that is the ONLY time in which any serious change to brain growth can be made. Everything is downhill after then. It is inescapable.
So extensive knowledge and good teaching will widen the age bracket some. How much is hard to say, but you could probably double or maybe even triple the useful working life of the brain.
Pffffft. Bush claimed it first, by Executive Order. That's politics as usual for you. Frankly, I'm less surprised about this than I am that there are so many Republicans out there who think voting for their candidate will help. Far from it. Under President Bush, assassinations by Hellfire missile in crowded city streets was standard practice. Unless you complained then, complaining now has no credibility.
Actually, no. I was at the talk and he actually stated that every time people predicted the end of physics, something new was discovered that revolutionized the field; that in this light he was going to predict the end of physics and the discovery of a theory of everything. As far as I'm concerned, he has achieved his objective. Something new has indeed been discovered and it does appear to have revolutionized the field.
To those who think Hawking is beyond his prime, I'll say maybe. No scientist likes to give up working in their field and Hawking has far fewer reasons than most to want to. One major contribution he can make is in describing how he models the physics in his mind. The depth of his mental agility is staggering and knowing how he achieves it would be extremely valuable. We know a little of Einstein's method, but it needs a team - I'd suggest at a minimum a physicist, an analyst trained in extracting specifications from experts whether or not the expert knows what the specifications are and an expert in thinking techniques. The idea would be that the physicist is the only one who knows what would be meaningful to ask and how to understand the answers, the analyst is the only person trained in using examples to unveil the underlying mechanisms and methods, and you still then need someone to turn this model into something that can actually be used by others.
What they are talking about really reduces to a variant of Ahmdals Law, but simply put scaling is always non-linear. There will be overheads per core for communication (why is why SMP over 16 CPUs is such a headache) and overheads per core within the OS for housekeeping (knowing what core a specific thread is running on, whether it is bound to that core, etc, and trying to schedule all threads to make best use of the cores available).
The more cores you have, the more state information is needed for a thread and the more possible permutations the scheduler must consider in order to be efficient. Which, in turn, means the scheduler is going to be bulkier.
(Scheduling is a variant of the box-packing problem, which is an NP-Complete problem, but it has the added catch that you only get a very short time to pack the threads in and scheduling policies - such as realtime and core-binding - must also be satisfied in addition to packing all the threads in.)
The more of this extra data you need, the slower task-switching becomes and the more of the cache you are hogging with stuff not actually tied to whatever the threads are actually doing. At some point, the degradation in performance will exactly equal the increase in performance for the extra cores. The claim is that this happens at 48 cores for modern OS'. This is plausible but it is unclear if it is an actual problem. Those same OS' are used on supercomputers of 64+ cores, by segregating the activities in each node. MOSIX, Kerrighd and other such mechanisms have allowed Linux kernels to migrate tasks from one node to another transparently. (ie: You don't know or care where the code runs, the I/O doesn't change at all.) The only reason Linux doesn't have clustering as standard is that Linus is waiting for cluster developers to produce a standard mechanism for process migration that also fits within the architectural standards already in use.
If you clustered a couple of hundred nodes, each with 48 cores, you're looking at having around 2000+ on the system. It wouldn't take a "rewrite" per-se, merely a few hooks and a standard protocol. To support a single physical node with more than 48 cores, you might need to split it into virtual nodes with 48 or fewer cores in each, but Linux already has support for virtualization so that's no big deal either.
Slashdot Mirror
My bad. It's still in service but not being built.
There are B-52s still being built. Admittedly, not using the original design and the only similarity with the original is the name, but they are there.
NASA should be funded in a similar way to the way the BBC is funded in the UK - given a fixed amount for a fixed length of time and a charter for that period of time, with zero interference permitted outside of the GAO verifying that the charter is being complied with to the limits possible given the funding. This hybrid state should have the right to make additional money and should have some of the rights granted to private organizations but not granted to public organizations, but also have some of the protections granted to the civil service.
This is the only way to give it the funding necessary without the political ties that corrupted the Space Shuttle program, leading to an overweight monstrosity.
The Constellation is the official Shuttle replacement. Wasn't there an unofficial replacement being designed (and maybe developed) by ex-NASA guys? That was cheaper, on-schedule and likely to actually work?
The aerospace industry is suffering from a lack of manpower right now. Both Boeing and EADS are failing to deliver. Sane competitors use times like those to their advantage. Foolish competitors sack their workforce instead.
Sure, these workers may not have ideal skills for other programs, but that's a matter of training. They already have skills in technologies that required far higher precision and far higher quality than most other projects would require - those are skills that would take a LONG time to teach. Moving workers onto new projects is efficient, sacking them and training new employees in all the stuff the old ones already knew is inefficient.
Anticipate, keep several steps ahead of the market, never over-specialize your employees, always exploit transferable skills, never waste a single resource, never give your competitor the chance to regain lost ground through ditched employees, a redundant employee is a wasted opportunity.
I'd make a lousy businessman.
You are correct, which is why it is all the more important for teachers of subjects such as histories or the humanities clearly distinguish between the two. It is by confusing the objective with the subjective that modern reporters excuse their lack of objectivity by claiming that it's all really subjective anyway. A gun was fired or it wasn't, a bridge was crossed or it wasn't, a battle was fought or it wasn't. These things may be subjectively interpreted, but their objective reality (or lack thereof) is independent of that interpretation.
It is fair enough that some things are not knowable - because records were destroyed, or because there was a concerted effort to conceal that information permanently - but there the fact that is known is that the historical data for a definitive answer does not exist. So there is still a definite split between objective facts and subjective views. In most real-world cases, there will be additional facts - the archaeological facts on the ground. These are "facts" in the sense of object A was found at location B with a context of C and scientific tests reveal D. Because the archaeological record can be tampered with, there is nothing that definitely links object A to a specific event or a specific person. Interpretation of such a record is largely subjective.
Actually, we can refine this two-way split a little further into a three-way split: The facts (insofar as they can be objectively known), the subjective views, and the deductive reasoning/critical thinking that allows you to produce "derivative facts" ("facts" for which no direct evidence exists but which explains both the facts that do exist AND the subjective views as far as can be reasonably done). Derivative facts are not truly objective (as different people may come to different conclusions) but neither are they truly subjective (assuming that the method used is based on the scientific method and has been shown to produce accurate conclusions when tested).
I'd say it depends on who is getting the money. Most sign shops are tiny, have no money to speak of and unreliable workloads.
If these are the sign shops that will be getting New York's money, then there will finally be some stimulus dollars where they need to be. That alone makes it "well spent".
I freely admit that, which is precisely why it scares me whenever anything that might encourage people to look for other views is slammed or eliminated.
People should be exposed to as many different views of historical events as possible, including the archaeological evidence on the ground as well as the subjective opinions of participants. The only time that I can consider restricting this to be acceptable is when someone has already done that legwork and endeavored to produce the most perspective-neutral account possible. I would consider that to be functionally the same as listening to the different views directly - to a degree. It's not possible to capture everything in a single account but critical thinking is not a skill taught in schools and you can't do much with the evidence alone without such a skill.
I give not a damn whether you are left-wing or right-wing, accuracy matters and honesty should come first above and beyond the whims of any faction. In this case, however, the whims come not from the left but from the extreme right. This matters only in that your own post is dishonest and that is no more acceptable than the dishonesty of anyone else.
The difference between history and propaganda is that history is what actually happened, whereas propaganda is what people want to have happened. It is important not to confuse the two. History is rarely taught, because what actually happened is rarely known.
The march through Russia will doubtless have been filled with heroic deeds, not least because of the extreme conditions they faced. Rommel, the commander of the German's African forces, performed many acts of heroism and is often held in high regard by military historians. Rudolph Hess is an interesting figure, not least because he managed to be reviled AND held as a hero by both sides simultaneously. That's no small achievement. A great uncle of mine who helped hold off the German forces whilst the rest of the allies escaped at Dunkirk maintained a diary of the retreat and then of his time as a POW. His description of the German forces shows a full range of people, ranging from the compassionate to the psychotic. His description is a far, far cry from what you'll see in any traditional history book.
Not all history is written by the victors. The Bayoux Tapestry, for example, was produced by the Saxons and depicts the Saxon view of the Battle of Hastings, not the Norman perspective.
Amazingly enough, Prince Charles has actually said a few things over the years that are actually quite smart. The idea that towns will function better if there's a well-defined center is sound. The idea that people prefer buildings to look good, as well as function well, is obvious. In this particular debate, he has been slammed on all sides but again appears to have made some valid points - it is possible to farm economically AND be ecologically sound. The two do not have to be in conflict.
Not sure about the cost-effectiveness of this one-man think-tank, but the topics he has ventured into are generally controversial and the corporations he's been battling are too big for most campaigns to be effective against.
I believe you are correct. I wonder what would have happened if EA had used what you'd said rather than their actual press release.
The large amount of US population has been happy to accept the aid of insurgent groups (the various resistance groups in Occupied Europe, for example) when it has been convenient. Indeed, the US was largely liberated from British rule by an insurgency. Unofficial groups that do not operate under the command of a State have existed throughout history and have been utilized by every nation on Earth. Until the Iraqi "Awakening Councils" were accepted by the government there, they too were unofficial militia operating outside of any central command structure. Don't recall hearing too many oppose them in the US.
The reason the Taliban aren't legitimate in the eyes of the US is that the US is fighting them. Everything else is a contrived excuse.
Well, in Japan they apparently teach history and play video games in which they win World War 2. This is highly important to them, but is not a war that is currently going on. I suspect that if EA produced a game in which you were a Vietnamese soldier fighting the Americans, the American public would oppose that as well, even though it's a war that's over, but a game in which you were an American beating the Vietnamese, that would be more likely to pass muster.
It's less about whether the war is going on (that's a feeble excuse), it's about imaginary national shame. If a person has that much shame, they should see a p-doc to deal with it, not censor others so that they can avoid ever having to face up to the fact they've serious issues.
Perhaps those wanting to reduce the reminders should also remove the "Support Our Troops" bumper stickers and every other reminder they voluntarily put up. In fact, aren't the families of those soldiers currently at war responsible for 99% of the reminders that exist? If they started there, they could eliminate almost all of the problem without ever having to go near the game.
Of course they shouldn't. The reality is that wargames depict a historical context and history doesn't change to suit the likes of one group or another. There is only one history, the events that took place.
Further, we learn from history that it is dangerous to make an enemy faceless. Doing so is the number one cause of wartime atrocities. What these pressure groups have basically said is that it is more important to hide the reality of the situation than it is to keep Americans aware that they are fighting against people with lives and beliefs of their own. This is a dangerous attitude to have.
I cannot blame a company for eventually caving under pressure, especially one as small as this. But frankly this whitewashing of history is disturbing and historically the consequences of such acts have never been good. This is extremely bad juju.
Since his position was not that we'd actually have a theory of anything (read through my post again) but rather would discover something new that would force us to abandon our prior notion of what a unified theory would be, he has NOT revised his position but actually demonstrated what he set out to demonstrate.
If you do not understand this, I will write out what he said in pseudo-code:
if (declare(physics) == complete)
{
fscanf(physics, "%s", newDiscovery);
prove(physics, incomplete);
}
I would say that assassination in general is a bad thing, no matter who does it or who to. For example, whilst I have some sympathy for the UK government at the time, assassinating three suspects in Gibraltar was not something I would consider legitimate. The problem was real, but that doesn't make the solution right.
I cannot think of a single assassination in history that has done anything other than create a hero out of the victim and produce the opposite of the intended result. There may be exceptions, but so very few of them in the scheme of things that you can effectively conclude that the world would be better from outlawing such practices. Utterly. (And I mean utterly. A President guilty of such an act should have no claim to sovereign immunity. If the ICJ has strong evidence of such a crime by such a person, they should have the right to prosecute and to hell with whether the nation is signed up or not.)
The brain grows in teenage years, this tails off in the mid 20s, then dies back where it is under-utilized. The insulation around the axons starts thinning around the age of 40, leading to accelerated degradation. This is why 22-32 is the time you're most likely to do anything interesting. It's when your brain is at maximum and you've the knowledge to make use of it. Though better teaching may give people the knowledge needed to do significant work at a younger age.
Since antidepressants and other drugs can stimulate brain growth, it is possible that you can hold off the die-back. If you learn multiple languages, the mental requirements appear to be great enough that you can prevent the brain from contracting as much. Currently, most of the evidence is circumstantial (people from the Age of Enlightenment often knew 4-8 languages and were able to produce constructive work at an advanced age), but since recent studies on depression show that seratonin levels are not as important as brain growth and the happiest nations are invariably the ones where multiple languages are taught, there is some basis for thinking that brain growth is absolutely tied to brain function.
If this is correct, then scientists who are over-specialized (and therefore do not use the full capacity of the brain but merely those aspects of the brain useful to their specialty) will stop contributing at an earlier age. If a scientist wishes to contribute for longer, they must stretch more of their brain more of the time. Further, education must be revamped to promote this. Brain-dead education will produce brain-dead people. Slowing deterioration at that point is worthless, and nothing can be done to boost a brain that isn't there. If you push the 9-18 age bracket to the absolute limit, they can filter out what they don't need/want later. But that is the ONLY time in which any serious change to brain growth can be made. Everything is downhill after then. It is inescapable.
So extensive knowledge and good teaching will widen the age bracket some. How much is hard to say, but you could probably double or maybe even triple the useful working life of the brain.
So what do we do about Brian May (Scientist/Rock Star)?
Pffffft. Bush claimed it first, by Executive Order. That's politics as usual for you. Frankly, I'm less surprised about this than I am that there are so many Republicans out there who think voting for their candidate will help. Far from it. Under President Bush, assassinations by Hellfire missile in crowded city streets was standard practice. Unless you complained then, complaining now has no credibility.
And this is different from all the other generics out there how?
Actually, no. I was at the talk and he actually stated that every time people predicted the end of physics, something new was discovered that revolutionized the field; that in this light he was going to predict the end of physics and the discovery of a theory of everything. As far as I'm concerned, he has achieved his objective. Something new has indeed been discovered and it does appear to have revolutionized the field.
To those who think Hawking is beyond his prime, I'll say maybe. No scientist likes to give up working in their field and Hawking has far fewer reasons than most to want to. One major contribution he can make is in describing how he models the physics in his mind. The depth of his mental agility is staggering and knowing how he achieves it would be extremely valuable. We know a little of Einstein's method, but it needs a team - I'd suggest at a minimum a physicist, an analyst trained in extracting specifications from experts whether or not the expert knows what the specifications are and an expert in thinking techniques. The idea would be that the physicist is the only one who knows what would be meaningful to ask and how to understand the answers, the analyst is the only person trained in using examples to unveil the underlying mechanisms and methods, and you still then need someone to turn this model into something that can actually be used by others.
VRML is indeed still around and there are some excellent editors/viewers for Linux and Windows. I suggest you read Freshmeat as well as Slashdot.
CodeSourcery produces a GPL version of VSIPL, which is a library for software DSP. That gives you the algorithms you need in a non-patented form.
What they are talking about really reduces to a variant of Ahmdals Law, but simply put scaling is always non-linear. There will be overheads per core for communication (why is why SMP over 16 CPUs is such a headache) and overheads per core within the OS for housekeeping (knowing what core a specific thread is running on, whether it is bound to that core, etc, and trying to schedule all threads to make best use of the cores available).
The more cores you have, the more state information is needed for a thread and the more possible permutations the scheduler must consider in order to be efficient. Which, in turn, means the scheduler is going to be bulkier.
(Scheduling is a variant of the box-packing problem, which is an NP-Complete problem, but it has the added catch that you only get a very short time to pack the threads in and scheduling policies - such as realtime and core-binding - must also be satisfied in addition to packing all the threads in.)
The more of this extra data you need, the slower task-switching becomes and the more of the cache you are hogging with stuff not actually tied to whatever the threads are actually doing. At some point, the degradation in performance will exactly equal the increase in performance for the extra cores. The claim is that this happens at 48 cores for modern OS'. This is plausible but it is unclear if it is an actual problem. Those same OS' are used on supercomputers of 64+ cores, by segregating the activities in each node. MOSIX, Kerrighd and other such mechanisms have allowed Linux kernels to migrate tasks from one node to another transparently. (ie: You don't know or care where the code runs, the I/O doesn't change at all.) The only reason Linux doesn't have clustering as standard is that Linus is waiting for cluster developers to produce a standard mechanism for process migration that also fits within the architectural standards already in use.
If you clustered a couple of hundred nodes, each with 48 cores, you're looking at having around 2000+ on the system. It wouldn't take a "rewrite" per-se, merely a few hooks and a standard protocol. To support a single physical node with more than 48 cores, you might need to split it into virtual nodes with 48 or fewer cores in each, but Linux already has support for virtualization so that's no big deal either.