Well I was specifically thinking of glibc (being the most essential library for any C program running under linux to link to), and it is definitely licensed under the LGPL.
And no, GNU doesn't think you should only use LGPL if you hate freedom. They do suggest that you strongly consider using the GPL instead since by allowing linking LGPL does Less to protect freedom. They would also say the same about GPL-with-linking-exception, only more so, since LGPL puts more requirements on what kind of things users should be able to do with the linked binary.
To be blunt here, I see little scientific value in changing a 70 year old official definition of planet. We don't become more stupid or less just because we change our minds about what characteristics acquire the label of planet. Nor do I agree that the "role" of Pluto has changed greatly since its discovery. The only significant change is that we now have discovered objects that we had already suspected were there.
The thing is, once you set aside that no formal definition of "planet" existed, we really aren't changing the definition of a planet, or the characteristics which acquire that label. They're essentially the same characteristics by which we say all of the 8 planets are planets. The same characteristics by which we first said Ceres was a planet, but then decided it wasn't when we learned more about it's neighborhood. Planets were expected to be the dominant objects in their orbits, and when it turned out Ceres wasn't, we stopped calling it a planet.
And Pluto's role has absolutely changed as our knowledge has increased. It was discovered in 1930 in the search for a 9th planet suspected to be the cause of perturbations in Uranus' orbit not explained by Neptune, and when found was presumed to be that planet. Over the next decades there were hypothesis of there being or having been a population objects past Neptune's orbit, though few such hypothesis looked anything like the actual Kuiper Belt. Also many (including Kuiper) hypothesized that Pluto, thought to be as massive as Earth, would have long since tossed all of those smaller objects out of its orbit (i.e. like a planet does) and so the belt had disappeared long ago in the solar system's development.
It wasn't until over 40 years later in the late 70s that we could actually measure Pluto's mass and realize just how small it was, and that it couldn't be the planet that caused the disturbance of Uranus (and which later measurement showed wasn't actually disturbed). It wasn't until the early 90s, less than 20 years ago, that we actually began finding other objects in the Kuiper Belt and began discovering its actual characteristics and the consequences to Pluto's role in its orbit as just the biggest asteroid in an asteroid belt, like Ceres, not the dominant object of its orbit, like every other planet.
So what changed is not the characteristics that get called a planet. What changed is: 1) the characteristics of Pluto as we understand them -- from earth-size and dominating its orbit, to a large asteroid in the midst of a belt. 2) the formalization of the classical definition of planet, such that we can't continue calling something that is clearly completely unlike every other planet a planet just because it's comfortable.
Like I said before, the only reason we ever called Pluto a planet is because we thought it had the characteristics that we attribute to the other planets. If you had proposed the IAU definition of planet back in the 1930s, everyone would have thought that Pluto met them. It does not. Regardless of the IAU definition, had we known in the 1930s about the Kuiper Belt, we would not have called Pluto a planet. Because it isn't one.
"Planet" used to mean roughly what it does today. Only when we knew that Pluto didn't fit at all, but still called it a planet, did the word get reduced to meaning "things which were historically called planets for whatever reason". I think there is great scientific value in making it mean something again. And there's an orders-of-magnitude distinction between that meaning and all the objects like Pluto that don't fit, so I think it is clearly indicating something meaningful.
I see two things that would have made the debate irrelevant for me. First, if the definition had been completed with the "neighborhood" element nailed down.
Having "neighborhood" be vaguely defined is actually a feature. Any precise definition would necessarily be an arbitrary one, and prevent reasoned analysis of individua
Baloney! Most people using the GPL use it because they understand it very well indeed.
I only meant that I can believe those people exist, not that more than a small number are actually using the GPL only because they are worried about compliance. Obviously most are using the GPL because they want to use it for their own projects or extensions to other projects.
Well, what is a derivative work? Guess what? The GPL itself doesn't define that term.
Of course it doesn't, since that term is defined by the legal code regarding copyright in your jurisdiction. Because the GPL is not anything else but a copyright license, it cannot apply to anything which is not a derivative work by the definition of the relevant legal code, because anything not a derivative work is not restricted by copyright law. So if the GPL did give a definition it would be irrelevant, and if it happened to differ from the legal definition at your current location in space-time, it would be wrong. How's an irrelevant and wrong definition going to reduce confusion, exactly?
But then you go and look at the legal code and see that, what do you know, the real definition of derivative work is vague. This is an issue that applies to all of copyright, and sparks many debates (and lawsuits), and has nothing specifically to do with the GPL. The lack of a clear definition is not something the GPL can fix.
It's trivially easy to comply with, but it's VERY hard to make a clear determination if the restrictions extend to you or not. So most people "just take the easy way out" and license GPL.
It's a fair point, that people license their own code GPL just because it's the only way to be sure they aren't violating the GPL of some other code they are using.
However the same issue of confusion applies in any situation where it matters whether you're creating a derivative work or not. With proprietary software, that means people "take the easy way out" and avoid doing anything with the software that could possibly be derivative. The only time the issue doesn't matter is when the license is so liberal it doesn't matter if your work is derivative or not because you can just repackage it with whatever license you want anyway.
And while BSD-style licenses are great for those who want to give away code, I don't think it's worth abandoning the advantages of Copyleft just to avoid the stick issue of what exactly constitutes a derivative work.
First, keep in mind that the orbit is the trajectory of the planet. The 3-dimensional paths we trace out are a convenient fiction and every Solar System body deviates to some degree from this path.
Okay, that's what you meant. It sounded like you were talking about some 4-D volume some distance from the object, and some fixed amount of time. I misunderstood.
But if we're talking about considering the whole orbit and a reasonable distance...
Aside possibly from an occasional visit by Eris, nothing larger than Pluto appears within 11 AU of Pluto. That's huge for an "immediate neighborhood", especially given that Pluto's closest approach to the Sun is 29 AU. Those numbers are comparable to the planets. Ceres probably has similar ratios as well.
So it's the biggest Kuiper Belt Object known. So what? There are several objects approaching its size in similar orbits known. Those plus all the smaller objects total over 10 times Pluto's mass. It's "neighborhood" looks nothing like the neighborhoods of the other planets. They've all cleared their orbits to the point where they dominate by at least 4 orders of magnitude. And while most of them have other small objects in their orbits, they're ones that have been gravitationally captured by the planet, either orbiting the planet or clustered around La Grange points. Aforementioned mass ratio means Pluto isn't close to dominating its orbit with its gravity. It's this gravitational dominance that clearly sets apart the 8 planets from Pluto and similar objects.
Just because the IAU settled on one particular heuristic approach for deciding what a planet is, which so happens to weed out Pluto, it is now a "mistake" to have ever called Pluto a planet. Can't you even see the problem with your words?
Just because primitive instruments meant that Pluto was the only object of its asteroid belt to be seen and assumed to be largely alone in its orbit like the other planets, the decision to call it a planet wasn't made out of ignorance? Not in a pejorative sense, but the literal meaning of "lacking knowledge"?
If the main asteroid belt had been discovered more or less all at once, then I doubt we would have ever called Ceres a planet. We did call it a planet, but it's not a planet, it's just the biggest rock that coalesced from the remnants of what could have been a planet but probably got ripped apart by Jupiter before it could congeal. It seems silly to call it a planet when it's surrounded by rubble of a comparable mass. And Ceres accounts for 1/3rd of the asteroid belt mass, a much greater ratio than Pluto. But because of the great distance Pluto orbits at, it took much longer for us to realize it was not a lone planet with a few objects clinging around, but part of an asteroid belt similar to the inner one.
We only called Pluto a planet because we didn't realize that, and so many people are complaining only because we just realized this recently so most of us grew up looking at diagrams that showed Pluto as the 9th planet. Those same diagrams show the asteroid belt, and of course we have no qualms about not calling Ceres a planet because it's obviously just a part of the belt, though big and interesting. In another generation the textbooks will show a second asteroid belt, and it'll seem quite logical that Pluto isn't classified as a planet, since it is just another component of the belt that is of scientific and historical interest.
Here's another heuristic choice for definition.
Okay, I realize that this whole exercise is about the human desire for names and classifications, and not a rule of the universe. I recognize that this means the real distinction is vague, and attempts to precisely define the criterion involve some amount of arbitrariness. Pointing that out is completely valid criticism.
On the other hand, this is a heuristic that is somewhat comparable to the criterion by which we first named Ceres and Pluto planets, and also comparable to the reason why we
Like what? Grasses in savannah/prairies/outback-bushland doesn't store/process carbon?
Less than tall trees, obviously. While medium-height shrubs would contain somewhere in between.
There are obvious deficiencies, like that they probably care about biomass density and you could have dense foliage under a shorter canopy. But it is a useful first-order indication. That's why they said the height map "helps get us there", not "is the end-all be-all, yippe we're done."
"Clearing the neighborhood" remains undefined and there are ways to define "neighborhood", as a large loci in space-time around the trajectory of the object in question, so that Pluto, and perhaps even Ceres and some of the dwarf planet candidates, clear their neighborhoods.
You have a fair point that the definition of "neighborhood" is vague, but all sensible attempts at least refer to the entire orbit and not just the immediate vicinity of the planet. By that standard, vagueness notwithstanding, it is obvious that Pluto and Ceres have not cleared their neighborhood and the eight planets have.
All the planets have masses which are at least several orders of magnitude larger than the rest of the mass in their orbit combined. Pluto is a small fraction of the rest of the mass in its orbit, less than 0.1. Ceres has a higher ratio than that, but it's still well under 1.
There's a huge gap in orbit-clearing ability that clearly distinguishes Pluto from Mars, and you can say it's possible to define your way around this clear and obvious distinction but that doesn't make the distinction go away.
Pluto is not a planet. It's a large Kupier Belt Object, but not one so large that it isn't just another asteroid in the belt. It was a mistake to ever call it a planet, and I'm sorry for everyone who grew up learning about the 9 planets and can't get used to the idea that the only reason we ever called it that is because we didn't know any better. Our telescopes sucked then compared to now; we were lucky to see it at all. Oh well, things change.
Yea, the only way we'd stand a good chance of finding a bigger star than this would be...well, let's just say there'd have to be thousands of stars for that to even be possible.
The odds of such a star existing is very, very different than the odds of us finding it. The circumstances where you'll find one aren't just anywhere. There are certainly plenty such places in the universe, but not so many where we could actually see them and resolve the individual stars, which was a challenge even in this case.
Unfortunately I'm mentally referencing a newspaper article from a couple years after the end of the Cold War, so I don't recall much in the way of details. It was part of a good will effort on both our parts to reveal some of the previously classified info. Obviously not all info was released, like I doubt they said which of our ICBM silos they had identified and targeted. I was googling earlier and found a map on WP showing "major" targets of Russian ICBMs so I know there was really information released and I'm not recalling a bad acid trip or anything but now I can't even find that.:P
Well yeah, the first line of the summary says "most massive", which in astronomy is usually (usually) what "biggest" means.
Though it is admittedly ambiguous. I was watching Jeopardy (a taped episode a friend of mine was in and *won*) and one of the answers was "It's the biggest planet after Jupiter and Saturn", and the correct question was "Neptune?" (the 3rd most massive) but the contestant questioned "Uranus?" (3rd largest diameter). The judges ended up accepting it due to the ambiguity of the question.
And I know that I personally consider the Jeopardy judges to be the ultimate authority on when something is ambiguous and multiple interpretations are valid!
Contrary to popular belief, most of the targets were military, rather than civilian - cities were a low priority, missile silos were a high priority, for reasons that should be obvious.
Yes most targets were pure military like missile silos, but "most" has a different meaning when you're talking about this number of missiles. At the height of the cold war, we had so many individual ICBMs pointed at each other that you could hit all the bases, all the large cities, and then start working your way down the list.
My home city of ~30k had an ICBM designated solely to wiping it off the map. A whole ICBM! Okay it was almost certainly nothing fancy, just one of the smaller fission weapons the Russians had so many of. They had so many that just the fact that my city had large automotive factories and was at the midpoint of the interstate leg linking two major cities -- cities that would have already been destroyed by much fancier thermonuclear devices -- made it enough of a military target to spare a missile.
I agree though that with most of the targets being in the northern hemisphere (and only a few countries at that), this wouldn't have spelled the extinction of the human race. That's why the everyone-dies laugh-fest that is On the Beach featured a war with China who used (still unrealistically) dirty cobalt bombs. Or you could probably do it on purpose.
I did read the article. B&W and Westinghouse, who also makes naval nukes, obviously aren't going to be building the same reactors, so what?
All the things you say about naval nuclear are real advantages for certain naval vessels, but that's not the same thing as it being economical. Oh sure, it's cheaper to have a nuclear plant on a sub than to run the logistical supply chain to keep it fueled up with diesel while coming up to the surface defeating the whole purpose of a nuclear missile attack sub. That's like saying the Space Shuttle is economical because it's cheaper than a staircase to the ISS especially since you still couldn't actually dock with it. What that's really saying is that the one option, regardless of cost, simply doesn't have the needed capability.
There are situations where a nuclear reactor has insurmountable advantages. Large carriers or cruisers, long-range attack or ballistic missile subs are places where that's the case. For more plentiful, cheaper vessels they don't use it. Because a Naval nuclear reactor isn't about cost, it's about the raw capabilities it provides.
Obviously the needs of such a reactor are very different than something that isn't being installed in a warship. I don't suppose that for some reason you thought I was saying small reactors couldn't be economical? That's not my point at all. My point is the Navy doesn't care about economics to a significant degree in the situations where only nukes will do, and there's nothing cheap about the ones they use and for good reason. Thus they are not an example of an economical small reactor.
It did not leak like a sieve. A sieve is a device that would leak continuously as it is a filtering apparatus.
It did leak continuously, until heat caused it to cease to be like a sieve.
The sr-71 did not really have fuel tanks the whole plane was the fuel tank and yes the skin did leak at the edges
Yes the skin and (other structural components) acted as the fuel tank and was heated by friction. They're still called fuel tanks just like JP7 is still called jet fuel.
You are perpetuating an urban myth.
As is every museum, documentary, books written by former pilots and maintenance crew...
but the leaks were not the amounts you seem to be indicating.
Sure, I see that I suggested leaking fuel contributed to the operational costs, and that's probably not true at all. I've seen pictures that show plenty of fuel leaking out, though obviously a tiny fraction of what's going through the engines. The plane was plenty expensive to operate without needing to throw in that it leaked fuel like a sieve as a factor. But, well, it did.:)
The Navy's plants are "not economical" for a pretty big reason.
I never meant to imply there weren't good reasons for it. I was implying that the Navy doesn't care if their nuke reactors are economical, and instead cares about all the aspects you mention and more.:)
They did however leak a very small amount of what they ended up calling jp7, but not like a sieve at all.
It was literally like a sieve in that the fuel leaked out of gaps in the fuel tanks continuously while it was on the ground. Thermal expansion would seal the tanks once the plane was at operating temperature, which is why they were designed that way in the first place, but until that point, it was a sieve.
Sorry if you took issue with the metaphorically implied quantity of the leaked (variety of) jet fuel, but I did say "literally" and meant it, well, literally.:)
Satellites avoided SAMs just fine, this just provided oversite on an on demand basis.
Yes. Satellites could not provide on-demand coverage, thus airplanes. Other airplanes could not reach the speeds and altitudes needed, thus the SR-71.
I think perhaps the GP meant "commercially" competitive. The Navy's reactors are certainly economical for the criteria they have: quiet, high power density, infrequent refueling, no oxygen requirement, reliable, etc.
They are not economical. They are simply the only thing that can provide all the capabilities that a naval nuclear reactor provides. When you have something that is incredibly expensive but with unique capabilities, you use it in spite of it being uneconomical.
The Saturn V was not an economical rocket at all. But it was the only thing that could launch the Apollo mission, so they used the uneconomical rocket.
The SR-71 was a stupidly expensive airplane both to build and to run (the fucker leaked jet fuel literally like a sieve until it got up to speed), but nothing else could fly high and fast enough to avoid Russian SAMs, so they used it.
Cost still factors in to the equation, but it would seem that gas turbines aren't cheap enough to offset the other benefits nuclear provides.
Nobody cares about cost when it comes to building aircraft carriers or attack/ballistic missile subs. The endeavor is inherently expensive and uneconomical. Gas turbines could cost negative one billion dollars and the Ohio-class submarine would still be sporting its expensive nuclear reactor.
Long and short of it is: Nuclear power plants are a fantastic choice for certain Naval operations. They are not, nor are they intended to be, economical.
I would assume the nuclear plants found on submarines and large warships both provide a lot of energy and are not in the category of 'extra large.'
Nor are they in the category of "economical", which is what was meant by "the prevailing wisdom is that nuclear plants must be very large in order to be competitive." Economically competitive, you see. Something the Navy cares about far less than, well, basically every other factor that goes into the design of a naval nuclear power plant.
once you understand that the speed of light is always constant, you arrive at the fact that the faster you're going, the less energy the light has. The light "shifts" to the red side of the spectrum.
Heh, yep. c stays constant, and instead the wavelength changes. What a bizarre and amazing universe we live in!:)
The Moon mission was dead a couple of years ago... it just took Congress this long to recognize that fact and a change in the presidency (or rather a new NASA administrator to wake up to the fact). Constellation, as it was proposed, was simply unsustainable and required federal spending on spaceflight to be proportional to what NASA got in the 1960's to get it to happen. There is no possible way that Congress would have ever forked out that kind of money for a sustained effort that would have lasted decades.
Yes all of that is true, yet Congress could have (and could still) force NASA to spend a large fraction of it's budget trying to recreate Apollo. The writing was on the wall as far as it actually happening, but that doesn't mean they couldn't have thrown more money down the pit.
In terms of orbital rocketry being similar to ICBMs, it should be pointed out that they are two very different engineering regimes and they don't really support each other...
Hey, it wasn't my theory, it was some Senator's, and I was trying to make fun of it.:)
It might just help advance the development of rocketry at the same time... something that the Ares I simply won't do.
Ares was awful. I've said before that if we have to do a shuttle-derivative, then it should be more like DIRECT than Constellation, and thank goodness that seems to be the new plan. I mean, compared to forcing NASA to continue developing Ares. I'd much rather both get dropped and NASA spends all it's budget on doing interesting things in space, not funding an expensive rocket to get to LEO.
Uh... more like you incorrectly thought that equation was valid for calculating acceleration to speeds approaching c, and Google faithfully did the math you told it to.
Not trying to be mean, but Newton need not apply for such a calculation and Google can't exactly be expected to know what you're trying to do. Also, TFS said 0.0002 pounds (not psi) of pressure (so uh, it should be psi but they gave force) per photon (which is just plain wrong, photon momentum = Plank's constant / wavelength, i.e. way smaller than that), so sadly your math was kinda screwed from the get go.
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Well I was specifically thinking of glibc (being the most essential library for any C program running under linux to link to), and it is definitely licensed under the LGPL.
And no, GNU doesn't think you should only use LGPL if you hate freedom. They do suggest that you strongly consider using the GPL instead since by allowing linking LGPL does Less to protect freedom. They would also say the same about GPL-with-linking-exception, only more so, since LGPL puts more requirements on what kind of things users should be able to do with the linked binary.
To be blunt here, I see little scientific value in changing a 70 year old official definition of planet. We don't become more stupid or less just because we change our minds about what characteristics acquire the label of planet. Nor do I agree that the "role" of Pluto has changed greatly since its discovery. The only significant change is that we now have discovered objects that we had already suspected were there.
The thing is, once you set aside that no formal definition of "planet" existed, we really aren't changing the definition of a planet, or the characteristics which acquire that label. They're essentially the same characteristics by which we say all of the 8 planets are planets. The same characteristics by which we first said Ceres was a planet, but then decided it wasn't when we learned more about it's neighborhood. Planets were expected to be the dominant objects in their orbits, and when it turned out Ceres wasn't, we stopped calling it a planet.
And Pluto's role has absolutely changed as our knowledge has increased. It was discovered in 1930 in the search for a 9th planet suspected to be the cause of perturbations in Uranus' orbit not explained by Neptune, and when found was presumed to be that planet. Over the next decades there were hypothesis of there being or having been a population objects past Neptune's orbit, though few such hypothesis looked anything like the actual Kuiper Belt. Also many (including Kuiper) hypothesized that Pluto, thought to be as massive as Earth, would have long since tossed all of those smaller objects out of its orbit (i.e. like a planet does) and so the belt had disappeared long ago in the solar system's development.
It wasn't until over 40 years later in the late 70s that we could actually measure Pluto's mass and realize just how small it was, and that it couldn't be the planet that caused the disturbance of Uranus (and which later measurement showed wasn't actually disturbed). It wasn't until the early 90s, less than 20 years ago, that we actually began finding other objects in the Kuiper Belt and began discovering its actual characteristics and the consequences to Pluto's role in its orbit as just the biggest asteroid in an asteroid belt, like Ceres, not the dominant object of its orbit, like every other planet.
So what changed is not the characteristics that get called a planet. What changed is:
1) the characteristics of Pluto as we understand them -- from earth-size and dominating its orbit, to a large asteroid in the midst of a belt.
2) the formalization of the classical definition of planet, such that we can't continue calling something that is clearly completely unlike every other planet a planet just because it's comfortable.
Like I said before, the only reason we ever called Pluto a planet is because we thought it had the characteristics that we attribute to the other planets. If you had proposed the IAU definition of planet back in the 1930s, everyone would have thought that Pluto met them. It does not. Regardless of the IAU definition, had we known in the 1930s about the Kuiper Belt, we would not have called Pluto a planet. Because it isn't one.
"Planet" used to mean roughly what it does today. Only when we knew that Pluto didn't fit at all, but still called it a planet, did the word get reduced to meaning "things which were historically called planets for whatever reason". I think there is great scientific value in making it mean something again. And there's an orders-of-magnitude distinction between that meaning and all the objects like Pluto that don't fit, so I think it is clearly indicating something meaningful.
I see two things that would have made the debate irrelevant for me. First, if the definition had been completed with the "neighborhood" element nailed down.
Having "neighborhood" be vaguely defined is actually a feature. Any precise definition would necessarily be an arbitrary one, and prevent reasoned analysis of individua
Wouldn't this mean that any software designed to run on Linux must be GPL its difficult to run on an OS without linking to any libraries?
The relevant libraries are licensed under the LGPL (which expressly allows linking) for precisely that reason.
Baloney! Most people using the GPL use it because they understand it very well indeed.
I only meant that I can believe those people exist, not that more than a small number are actually using the GPL only because they are worried about compliance. Obviously most are using the GPL because they want to use it for their own projects or extensions to other projects.
Well, what is a derivative work? Guess what? The GPL itself doesn't define that term.
Of course it doesn't, since that term is defined by the legal code regarding copyright in your jurisdiction. Because the GPL is not anything else but a copyright license, it cannot apply to anything which is not a derivative work by the definition of the relevant legal code, because anything not a derivative work is not restricted by copyright law. So if the GPL did give a definition it would be irrelevant, and if it happened to differ from the legal definition at your current location in space-time, it would be wrong. How's an irrelevant and wrong definition going to reduce confusion, exactly?
But then you go and look at the legal code and see that, what do you know, the real definition of derivative work is vague. This is an issue that applies to all of copyright, and sparks many debates (and lawsuits), and has nothing specifically to do with the GPL. The lack of a clear definition is not something the GPL can fix.
It's trivially easy to comply with, but it's VERY hard to make a clear determination if the restrictions extend to you or not. So most people "just take the easy way out" and license GPL.
It's a fair point, that people license their own code GPL just because it's the only way to be sure they aren't violating the GPL of some other code they are using.
However the same issue of confusion applies in any situation where it matters whether you're creating a derivative work or not. With proprietary software, that means people "take the easy way out" and avoid doing anything with the software that could possibly be derivative. The only time the issue doesn't matter is when the license is so liberal it doesn't matter if your work is derivative or not because you can just repackage it with whatever license you want anyway.
And while BSD-style licenses are great for those who want to give away code, I don't think it's worth abandoning the advantages of Copyleft just to avoid the stick issue of what exactly constitutes a derivative work.
We're trying to make space flight more economical.
A bigger capsule would be heavier. Economical and heavy are opposites in space flight.
First, keep in mind that the orbit is the trajectory of the planet. The 3-dimensional paths we trace out are a convenient fiction and every Solar System body deviates to some degree from this path.
Okay, that's what you meant. It sounded like you were talking about some 4-D volume some distance from the object, and some fixed amount of time. I misunderstood.
But if we're talking about considering the whole orbit and a reasonable distance...
Aside possibly from an occasional visit by Eris, nothing larger than Pluto appears within 11 AU of Pluto. That's huge for an "immediate neighborhood", especially given that Pluto's closest approach to the Sun is 29 AU. Those numbers are comparable to the planets. Ceres probably has similar ratios as well.
So it's the biggest Kuiper Belt Object known. So what? There are several objects approaching its size in similar orbits known. Those plus all the smaller objects total over 10 times Pluto's mass. It's "neighborhood" looks nothing like the neighborhoods of the other planets. They've all cleared their orbits to the point where they dominate by at least 4 orders of magnitude. And while most of them have other small objects in their orbits, they're ones that have been gravitationally captured by the planet, either orbiting the planet or clustered around La Grange points. Aforementioned mass ratio means Pluto isn't close to dominating its orbit with its gravity. It's this gravitational dominance that clearly sets apart the 8 planets from Pluto and similar objects.
Just because the IAU settled on one particular heuristic approach for deciding what a planet is, which so happens to weed out Pluto, it is now a "mistake" to have ever called Pluto a planet. Can't you even see the problem with your words?
Just because primitive instruments meant that Pluto was the only object of its asteroid belt to be seen and assumed to be largely alone in its orbit like the other planets, the decision to call it a planet wasn't made out of ignorance? Not in a pejorative sense, but the literal meaning of "lacking knowledge"?
If the main asteroid belt had been discovered more or less all at once, then I doubt we would have ever called Ceres a planet. We did call it a planet, but it's not a planet, it's just the biggest rock that coalesced from the remnants of what could have been a planet but probably got ripped apart by Jupiter before it could congeal. It seems silly to call it a planet when it's surrounded by rubble of a comparable mass. And Ceres accounts for 1/3rd of the asteroid belt mass, a much greater ratio than Pluto. But because of the great distance Pluto orbits at, it took much longer for us to realize it was not a lone planet with a few objects clinging around, but part of an asteroid belt similar to the inner one.
We only called Pluto a planet because we didn't realize that, and so many people are complaining only because we just realized this recently so most of us grew up looking at diagrams that showed Pluto as the 9th planet. Those same diagrams show the asteroid belt, and of course we have no qualms about not calling Ceres a planet because it's obviously just a part of the belt, though big and interesting. In another generation the textbooks will show a second asteroid belt, and it'll seem quite logical that Pluto isn't classified as a planet, since it is just another component of the belt that is of scientific and historical interest.
Here's another heuristic choice for definition.
Okay, I realize that this whole exercise is about the human desire for names and classifications, and not a rule of the universe. I recognize that this means the real distinction is vague, and attempts to precisely define the criterion involve some amount of arbitrariness. Pointing that out is completely valid criticism.
On the other hand, this is a heuristic that is somewhat comparable to the criterion by which we first named Ceres and Pluto planets, and also comparable to the reason why we
Like what? Grasses in savannah/prairies/outback-bushland doesn't store/process carbon?
Less than tall trees, obviously. While medium-height shrubs would contain somewhere in between.
There are obvious deficiencies, like that they probably care about biomass density and you could have dense foliage under a shorter canopy. But it is a useful first-order indication. That's why they said the height map "helps get us there", not "is the end-all be-all, yippe we're done."
"Clearing the neighborhood" remains undefined and there are ways to define "neighborhood", as a large loci in space-time around the trajectory of the object in question, so that Pluto, and perhaps even Ceres and some of the dwarf planet candidates, clear their neighborhoods.
You have a fair point that the definition of "neighborhood" is vague, but all sensible attempts at least refer to the entire orbit and not just the immediate vicinity of the planet. By that standard, vagueness notwithstanding, it is obvious that Pluto and Ceres have not cleared their neighborhood and the eight planets have.
All the planets have masses which are at least several orders of magnitude larger than the rest of the mass in their orbit combined. Pluto is a small fraction of the rest of the mass in its orbit, less than 0.1. Ceres has a higher ratio than that, but it's still well under 1.
There's a huge gap in orbit-clearing ability that clearly distinguishes Pluto from Mars, and you can say it's possible to define your way around this clear and obvious distinction but that doesn't make the distinction go away.
Pluto is not a planet. It's a large Kupier Belt Object, but not one so large that it isn't just another asteroid in the belt. It was a mistake to ever call it a planet, and I'm sorry for everyone who grew up learning about the 9 planets and can't get used to the idea that the only reason we ever called it that is because we didn't know any better. Our telescopes sucked then compared to now; we were lucky to see it at all. Oh well, things change.
Yea, the only way we'd stand a good chance of finding a bigger star than this would be...well, let's just say there'd have to be thousands of stars for that to even be possible.
The odds of such a star existing is very, very different than the odds of us finding it. The circumstances where you'll find one aren't just anywhere. There are certainly plenty such places in the universe, but not so many where we could actually see them and resolve the individual stars, which was a challenge even in this case.
Unfortunately I'm mentally referencing a newspaper article from a couple years after the end of the Cold War, so I don't recall much in the way of details. It was part of a good will effort on both our parts to reveal some of the previously classified info. Obviously not all info was released, like I doubt they said which of our ICBM silos they had identified and targeted. I was googling earlier and found a map on WP showing "major" targets of Russian ICBMs so I know there was really information released and I'm not recalling a bad acid trip or anything but now I can't even find that. :P
I edited for brevity. Though I think it would be funny if simply giving the "answer" with an upturned inflection was sufficient.
Well yeah, the first line of the summary says "most massive", which in astronomy is usually (usually) what "biggest" means.
Though it is admittedly ambiguous. I was watching Jeopardy (a taped episode a friend of mine was in and *won*) and one of the answers was "It's the biggest planet after Jupiter and Saturn", and the correct question was "Neptune?" (the 3rd most massive) but the contestant questioned "Uranus?" (3rd largest diameter). The judges ended up accepting it due to the ambiguity of the question.
And I know that I personally consider the Jeopardy judges to be the ultimate authority on when something is ambiguous and multiple interpretations are valid!
Two theories, now let's sit back and see who's right!
I think he'll be right for human scales of "soon", and you'll be right for cosmological scales.
Contrary to popular belief, most of the targets were military, rather than civilian - cities were a low priority, missile silos were a high priority, for reasons that should be obvious.
Yes most targets were pure military like missile silos, but "most" has a different meaning when you're talking about this number of missiles. At the height of the cold war, we had so many individual ICBMs pointed at each other that you could hit all the bases, all the large cities, and then start working your way down the list.
My home city of ~30k had an ICBM designated solely to wiping it off the map. A whole ICBM! Okay it was almost certainly nothing fancy, just one of the smaller fission weapons the Russians had so many of. They had so many that just the fact that my city had large automotive factories and was at the midpoint of the interstate leg linking two major cities -- cities that would have already been destroyed by much fancier thermonuclear devices -- made it enough of a military target to spare a missile.
I agree though that with most of the targets being in the northern hemisphere (and only a few countries at that), this wouldn't have spelled the extinction of the human race. That's why the everyone-dies laugh-fest that is On the Beach featured a war with China who used (still unrealistically) dirty cobalt bombs. Or you could probably do it on purpose.
I did read the article. B&W and Westinghouse, who also makes naval nukes, obviously aren't going to be building the same reactors, so what?
All the things you say about naval nuclear are real advantages for certain naval vessels, but that's not the same thing as it being economical. Oh sure, it's cheaper to have a nuclear plant on a sub than to run the logistical supply chain to keep it fueled up with diesel while coming up to the surface defeating the whole purpose of a nuclear missile attack sub. That's like saying the Space Shuttle is economical because it's cheaper than a staircase to the ISS especially since you still couldn't actually dock with it. What that's really saying is that the one option, regardless of cost, simply doesn't have the needed capability.
There are situations where a nuclear reactor has insurmountable advantages. Large carriers or cruisers, long-range attack or ballistic missile subs are places where that's the case. For more plentiful, cheaper vessels they don't use it. Because a Naval nuclear reactor isn't about cost, it's about the raw capabilities it provides.
Obviously the needs of such a reactor are very different than something that isn't being installed in a warship. I don't suppose that for some reason you thought I was saying small reactors couldn't be economical? That's not my point at all. My point is the Navy doesn't care about economics to a significant degree in the situations where only nukes will do, and there's nothing cheap about the ones they use and for good reason. Thus they are not an example of an economical small reactor.
It did not leak like a sieve. A sieve is a device that would leak continuously as it is a filtering apparatus.
It did leak continuously, until heat caused it to cease to be like a sieve.
The sr-71 did not really have fuel tanks the whole plane was the fuel tank and yes the skin did leak at the edges
Yes the skin and (other structural components) acted as the fuel tank and was heated by friction. They're still called fuel tanks just like JP7 is still called jet fuel.
You are perpetuating an urban myth.
As is every museum, documentary, books written by former pilots and maintenance crew...
but the leaks were not the amounts you seem to be indicating.
Sure, I see that I suggested leaking fuel contributed to the operational costs, and that's probably not true at all. I've seen pictures that show plenty of fuel leaking out, though obviously a tiny fraction of what's going through the engines. The plane was plenty expensive to operate without needing to throw in that it leaked fuel like a sieve as a factor. But, well, it did. :)
The Navy's plants are "not economical" for a pretty big reason.
I never meant to imply there weren't good reasons for it. I was implying that the Navy doesn't care if their nuke reactors are economical, and instead cares about all the aspects you mention and more. :)
They did however leak a very small amount of what they ended up calling jp7, but not like a sieve at all.
It was literally like a sieve in that the fuel leaked out of gaps in the fuel tanks continuously while it was on the ground. Thermal expansion would seal the tanks once the plane was at operating temperature, which is why they were designed that way in the first place, but until that point, it was a sieve.
Sorry if you took issue with the metaphorically implied quantity of the leaked (variety of) jet fuel, but I did say "literally" and meant it, well, literally. :)
Satellites avoided SAMs just fine, this just provided oversite on an on demand basis.
Yes. Satellites could not provide on-demand coverage, thus airplanes. Other airplanes could not reach the speeds and altitudes needed, thus the SR-71.
Unique capabilities.
It also has a bidet function, which isn't wimpy and French; it's got a firehose pump powered by a small nuclear plant.
Ya almost had me up to that point, ya cheese-eating pansy!
I think perhaps the GP meant "commercially" competitive. The Navy's reactors are certainly economical for the criteria they have: quiet, high power density, infrequent refueling, no oxygen requirement, reliable, etc.
They are not economical. They are simply the only thing that can provide all the capabilities that a naval nuclear reactor provides. When you have something that is incredibly expensive but with unique capabilities, you use it in spite of it being uneconomical.
The Saturn V was not an economical rocket at all. But it was the only thing that could launch the Apollo mission, so they used the uneconomical rocket.
The SR-71 was a stupidly expensive airplane both to build and to run (the fucker leaked jet fuel literally like a sieve until it got up to speed), but nothing else could fly high and fast enough to avoid Russian SAMs, so they used it.
Cost still factors in to the equation, but it would seem that gas turbines aren't cheap enough to offset the other benefits nuclear provides.
Nobody cares about cost when it comes to building aircraft carriers or attack/ballistic missile subs. The endeavor is inherently expensive and uneconomical. Gas turbines could cost negative one billion dollars and the Ohio-class submarine would still be sporting its expensive nuclear reactor.
Long and short of it is: Nuclear power plants are a fantastic choice for certain Naval operations. They are not, nor are they intended to be, economical.
I would assume the nuclear plants found on submarines and large warships both provide a lot of energy and are not in the category of 'extra large.'
Nor are they in the category of "economical", which is what was meant by "the prevailing wisdom is that nuclear plants must be very large in order to be competitive." Economically competitive, you see. Something the Navy cares about far less than, well, basically every other factor that goes into the design of a naval nuclear power plant.
once you understand that the speed of light is always constant, you arrive at the fact that the faster you're going, the less energy the light has. The light "shifts" to the red side of the spectrum.
Heh, yep. c stays constant, and instead the wavelength changes. What a bizarre and amazing universe we live in! :)
The Moon mission was dead a couple of years ago... it just took Congress this long to recognize that fact and a change in the presidency (or rather a new NASA administrator to wake up to the fact). Constellation, as it was proposed, was simply unsustainable and required federal spending on spaceflight to be proportional to what NASA got in the 1960's to get it to happen. There is no possible way that Congress would have ever forked out that kind of money for a sustained effort that would have lasted decades.
Yes all of that is true, yet Congress could have (and could still) force NASA to spend a large fraction of it's budget trying to recreate Apollo. The writing was on the wall as far as it actually happening, but that doesn't mean they couldn't have thrown more money down the pit.
In terms of orbital rocketry being similar to ICBMs, it should be pointed out that they are two very different engineering regimes and they don't really support each other...
Hey, it wasn't my theory, it was some Senator's, and I was trying to make fun of it. :)
It might just help advance the development of rocketry at the same time... something that the Ares I simply won't do.
Ares was awful. I've said before that if we have to do a shuttle-derivative, then it should be more like DIRECT than Constellation, and thank goodness that seems to be the new plan. I mean, compared to forcing NASA to continue developing Ares. I'd much rather both get dropped and NASA spends all it's budget on doing interesting things in space, not funding an expensive rocket to get to LEO.
Uh... more like you incorrectly thought that equation was valid for calculating acceleration to speeds approaching c, and Google faithfully did the math you told it to.
Not trying to be mean, but Newton need not apply for such a calculation and Google can't exactly be expected to know what you're trying to do. Also, TFS said 0.0002 pounds (not psi) of pressure (so uh, it should be psi but they gave force) per photon (which is just plain wrong, photon momentum = Plank's constant / wavelength, i.e. way smaller than that), so sadly your math was kinda screwed from the get go.