Uh, Radiation? You don't need air to "carry heat away" Radiative transfer is proportional to delta T ^4
But it's not as efficient as conduction and convection until you reach temperatures that are way too hot for a chip.
It would be just like operating a CPU without a heat sink, except that the chip wouldn't also be receiving thermal radiation from other objects in the room.
Of fucking course all orbits are planar, and you don't need Kepler's frickin' laws to prove it, just the fact that the only data defined in a planetary orbit are a point (center) and a vector (the velocity of the object) attached to the second point. All you can define with a point and a line in 3d space is a plane, hence orbits have to be planar.
You left out the acceleration, and the requirement that the force on the planet needs to be a central force from your origin where r=0.
Dark matter comes in two varieties: "cold dark matter" and "hot dark matter". Neutrinos are examples of "hot" dark matter because their speeds are close to c.
The observed mass distributions of galaxies implies that there is some stuff that gathers in clumps to form walls, voids, etc. So it must be "cold", because if it were composed of "hot" fast-moving particles, these structures would have dissipated by now. Neutrinos contribute to the overall mass of the universe (if they have mass), but they have been ruled out as cold dark matter candidates.
A 'Hello World' applet run using appletviewer. Ok cpu usage is at 0.0% which is to be expected since the applet doesn't do anything once it's painted the display, but look at RSIZE. 13.4M.
Yeah, that's the VM overhead, so?
And you can expect that number to blow out pretty quickly as the code is extended to make it do something useful.
I assume that adding features in your favorite language actually causes memory use to shrink?
Hello World in C has a resident size of 304K. Granted that's just using printf to output to a console but it's still a dramatic difference.
Actually, 304K seems like a hell of a lot of memory to lose for a Hello World in C.
You might want to take a look at "rotovator" systems, which rely on reaction mass from the ground (or on momentum transfers from rocks in space being lowered to Earth) to keep them in orbit, but which therefore don't need to be tethered to the ground and so don't need to be in a geosynchronous orbit. You spin the entire rotovator in such a way that its tips come to a brief stop in the atmosphere for payloads to be attached, and counterintuitively this allows the rotovator to be much shorter, lighter, and less stressed than a geosynchronous elevator would be. Geosynchronous beanstalks on Earth pretty much require supermaterials like buckytubes; you might be able to pull off a rotovator with Kevlar.
I was thinking of something similar... geosynchronous orbits are too far away to be practical. The earth just doesn't spin fast enough.
Instead we might have a space station (at a higher orbit than the silly ISS) lower a fishing line down just to the edge of the atmosphere. A small rocket could deliver a payload just high enough to reach the grappling hook, and then the space station would reel the payload in. This way, the rocket delivering the payload doesn't have to supply it with its orbital momentum; that comes from the orbiting satellite.
Of course both these ideas (space elevator or otherwise) require some massive object in a stable orbit around the earth, and that would be really expensive to set up even if it's just a space rock.
OK, first some clarification. This is the original AC post that I replied to originally:
Your understanding is wrong. A geosynchronous orbit is merely one which orbits such that it is always above a fixed point on the earth's surface.
(Which is wrong, this is a definition of a geostationary orbit like you said.)
There are 3 competing designs for a geosynchronous space elevator- the "tower" (CM lower than geosync orbit), the "rope" (CM higher than geosync orbit), and the "zeppelin" (CM exactly at geosync orbit).
The tower requires support from the ground. The rope requires a tether to the ground. Only the zeppelin requires no coupling to the ground, which means it can use a non-geostationary orbit, but it's the least stable design since as soon as you get on it, rockets have to start firing at the top for the system to maintain itself in its position.
I guess the rope and tower could both be supported by a ship in the ocean that moved around in a figure 8 forever, but it would be much more practical to use a geostationary orbit in both cases. (Not that the word "practical" has any place at all in this discussion.)
Pipes. The space elevator is a thin carbon nano-tube ribbon, you can't pump anything up it. And the pipes would need a weight to length ratio of roughly the same (7.5kg per km) and have a massive tensile strength since the weight of that 'weightless' hydrazine would be massive.
You wouldn't pump the hydrazine up through the nanotubes. That would be silly. You wouldn't have a simple hose connected to the length of the elevator either, because the mgh pressure at the bottom would be ridiculous. Getting fluid of any sort up there would require a sort of active transport system, like a mechanized bucket brigade. Which is similar to how water systems in skyscrapers work. This requirement can be met by simply having the passengers take the hydrazine up there with them. Although I think you recognize that I was simplifying for the sake of argument.
You would need to also maintain the CM at exactly geosynch at all times, not correct afterwards, since then you would need to deal with intertia of the cable falling to earth, and you are essentially lifting 20 tonnes via conventional rockets plus a nice 35,000+ km cable, somewhat inefficient (some would say stupid, but not me:) ).
Keeping the CM just slightly outside geosync at all times would be best.
Second, with the ground based anchor, contrary to popular misconceptions the centre of mass is always EXACTLY at geosynch
Actually, with a ground based anchor, the center of mass is only microns away from the center of the earth! Although your observation that the CM is orbiting geosynchronously is still correct, since it still moves around the center once per day in a tiny little circle down there.
You think the people protesting don't care about the civil rights? Do you have any clue how much of a legal fight it was to exercise their First Amendment rights in New York Saturday?
No kidding. Did you see this little gem in the New York Sun?
Mayor Bloomberg and Police Commissioner Kelly are doing the people of New York and the people of Iraq a great service by delaying and obstructing the anti-war protest planned for February 15. The longer they delay in granting the protesters a permit, the less time the organizers have to get their turnout organized, and the smaller the crowd is likely to be. And we wouldn't want to overstate the matter, but, at some level, the smaller the crowd, the more likely that President Bush will proceed with his plans to liberate Iraq. And the more likely, in that case, that the Iraqi people will be freed and the citizens of New York will be rescued from the threat of an Iraqi-aided terrorist attack.
In a federal court action filed yesterday, the New York Civil Liberties Union, representing the anti-war protesters, cites the First Amendment to the U.S. Constitution. The court action seeks a court injunction that would allow the protesters to march down First Avenue near the United Nations. "A central part of the February 15 event is to convey a message to the United Nations about opposition to any war against Iraq," the complaint filed yesterday says. But the right of peaceable assembly in the Constitution refers to the right "to petition the government for a redress of grievances." The protesters would be on stronger ground if they wanted to convey a message to the U.S. Mission to the United Nations -- if, in other words, if they were petitioning the government, not the U.N.
The protesters probably do have a claim under the right to free speech. Never mind that it's not the speech that the city is objecting to -- it's the marching in the streets, blocking traffic, and requiring massive police protection. So long as the protesters are invoking the Constitution, they might have a look at Article III. That says, "Treason against the United States shall consist only in levying war against them, or in adhering to their enemies, giving them aid and comfort. No person shall be convicted of treason unless on the testimony of two witnesses to the same overt act, or on confession in open court."
There can be no question at this point that Saddam Hussein is an enemy of America. Iraq was the only Arab-Muslim country that did not condemn the September 11 attacks against the United States. A commentary of the official Iraqi station on September 11 stated that America was "...reaping the fruits of [its] crimes against humanity." A government employee in Iraq reacted to the loss this month of the space shuttle Columbia by telling Reuters, "God is avenging us."
And there is no reason to doubt that the "anti-war" protesters -- we prefer to call them protesters against freeing Iraq -- are giving, at the very least, comfort to Saddam Hussein. In a television interview aired this week, Saddam said, "First of all we admire the development of the peace movement around the world in the last few years. We pray to God to empower all those working against war and for the cause of peace and security based on just peace for all." After the last big anti-war protest, the one in Washington last month, Saddam hailed the anti-war protests as proof that Americans back Iraq rather than President Bush. "They are supporting you because they know that evildoers target Iraq to silence and dissenting voice to their evil and destructive policies," Saddam told senior officers, including his son Qusay, commander of the Republican Guard. So the New York City police could do worse, in the end, than to allow the protest and send two witnesses along for each participant, with an eye toward preserving at least the possibility of an eventual treason prosecution. Thus fully respecting not just some, but all of the constitutional principles at stake.
To those concerned about civil liberties, we'd cite the pragmatic argument made last night by, of all people, the New York Times's three-time Pulitzer-Prize winning foreign affairs columnist, Thos. Friedman. "I believe we are one more 9/11 away from the end of the open society," Mr. Friedman told an American Jewish Committee dinner honoring the chief executive of the New York Times Company, Russell Lewis. His point was that if terrorists strike again at America and kill large numbers of Americans, the pressure to curb civil liberties and civil rights will be "enormous and unstoppable." What we took from that was that the more successful the protesters are in making their case in New York, the less chance they'll have the precious constitutional freedom to protest here the next time around.
I can imagine a 100,000km elevator coiled up in the australian desert, then a shuttle launched with it tied to the back. The huge coil slowly unwinds, only to be dragged across Australia, levelling perth!
And in the end, the damn rabbits just dig holes right underneath it anyway.
But perhaps just as importantly, the bottom of a geosynchronous elevator design needs to touch the ground because it needs the base to be pulling down on it, not lifting up. If you want to take a 20 ton payload up the elevator without pulling it down, then the elevator is going to need to be under at least 20 tons of tension at the ground when there is no payload on it.
Naah, not necessarily.
Say (for simplicity of argument) we have a free-floating design, with a basket hanging a few feet off the ground. In equilibrium, the center of mass of the entire elevator (basket, cable, counterweight) is in geosynchronous orbit.
You put a 20 ton payload into the basket. This shifts the CM downward by an amount. So you pump (weightless) hydrazine up the elevator to corrective rockets sitting on the counterweight, and the rockets push the CM back up into geosynchrous orbit. They do this by pushing the counterweight into a realm above geosync orbit where it experiences a centrifugal force of 20 tons in the upward direction, and this equilibrates with the 20 tons pulling down on the ground. Of course the centrifugal force isn't a "real" force, it's really just an artifact of inertial effects within a rotating coordinate system.
Once the CM is in stable orbit again it doesn't matter what you do with forces internal to the orbiting assembly, i.e. between the counterweight and the basket. Pulling the basket up to the level of the counterweight won't alter the CM placement. (Although sideways Coriolis forces on the rising 20 tons will start complicating things on the way up.) Still, the amount of rocket fuel spent raising the payload into orbit this way is much less than with a conventional rocket.
Your design is slightly different in that you have the CM sitting outside geosynchronous orbit in the realm where it experiences the outward centrifugal force all the time. So you've got the other end attached to the ground, pulling up on it. This is conceptually a little bit simpler to grasp, but it puts increased tension in the cable, and after lifting a certain amount of stuff into orbit, the CM of the system will reach geosynchronous orbit anyway- and all the tension at the ground will be gone.
Your understanding is wrong. A geosynchronous orbit is merely one which orbits such that it is always above a fixed point on the earth's surface.
Seems that his understanding is right on target. Your definition is correct, but a moment of thought should be all you need to realize that no geosynchronous orbit can exist where this "fixed point" is not on the equator. Otherwise the orbit doesn't conserve angular momentum. Can you imagine a geosynchronous orbit over the North Pole for example? How would that work?
All geosynchronous satellites occupy positions in the same orbital path, which forms a ring in the plane of the earth's equator.
There's no reason (in theory) why the bottom has to be anchored to the ground (although it probably would have to be to reduce tension on the elevator material). Ideally the elevator could be set up so that the bottom would hang a few feet off the ground in midair.
There's also no reason why the top would "lag behind a bit". In fact the orbital speed of the counterweight will tend to increase, not decrease, if the orbit decays below geosynchronous orbit. So it would tend to lag forward, not behind. It would definitely need a transport system to carry rocket fuel up to the counterweight for corrective thrust.
The real reason why one hasn't been built is the extreme material strength required. Nobody has yet developed a material that can hang suspended for a length of 30,000 miles without breaking. This is why most designs count on the bottom of the elevator touching the ground, so that a significant portion of the elevator's weight can be supported by contact with the earth instead of tension in the elevator. Another mitigating factor is the weightlessness of the material at high altitudes- the parts up near the counterweight hardly contribute any tension at all and can be built especially thick. Even with these two caveats, the required tensile strength is so high that people still talk about exotic materials like buckytubes and single-crystal metals whenever the topic of the space elevator comes up. Without some breakthrough in materials engineering, the project is essentially hopeless.
I can't find one without those pesky Windows keys, for example.
I work with a guy whose keyboard seems to have been designed by an AOL user interface expert. It has FOUR Windows keys! One between each Alt and Ctrl, plus two more under "Insert" and "Page Down"! (Of course it has the rubber chiclet "buy overpriced crap" keys running across the top as well.) He hates it and I keep telling him to get a new one. Trying to do any work on it is difficult, because if you hit one of the Windows keys the Start menu comes up and steals focus. It's like typing on a minefield.
The Windows key is the most useless key on the keyboard. Although it does come in handy in some cases, like when you want to break loose from a full screen demo in a Radio Shack store display.
I agree with you on this point, but then I sit back and think about it: Am I really that interesting?
I've decided that although personal privacy and freedom are very important, if some weirdo (capitol or otherwise) really wants to see what kinda of pr0n I look at or wants to listen in on my phone conversations (which almost always consist of "So, Starbucks or cyber cafe first?"), let them. Maybe they will get some sort of insight that in general, people aren't worth listening to.
People who smoke marijuana tend not to be very interesting either. They make silly observations that they mistake for profound insights. They're preoccupied with chips and chocolate. They keep forgetting what they were talking about.
And yet the nation's prisons are packed with them, so clearly someone is interested.
If you're going to do a DoS attack, at least do it right, with an army of infected machines taking orders from you over IRC. Even a script kiddie knows you don't hammer away at someone from your own IP using a browser and an HTML frameset. Being charged as a cyberterrorist for doing something like that would generally be considered extremely lame.
Also, the situation on the other end isn't necessarily what you think it is. The URL often doesn't point to the spammer's own server. Spammers have nothing of any worth to sell themselves, so they approach stupid small businesses like pornographers, credit services, etc. The sales pitch is that the spammer is selling web page hits, not emails, and they only have to pay for actual page loads to their site. So he makes a fraction of a penny off them every time a request hits the server with his URL parameter attached. You should at least remove all URL parameters so that nobody profits from your DOS attack.
Re:AS long as thay have anonomous cash
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The Future of Money
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· Score: 4, Insightful
You'd have to be out of your mind to buy a copy of 2600 with a credit card. Are you oblivious to the digital slime trail that your daily activities are leaving behind you? How many lists do you think you're on?
Some idiots in the government recently examined all of Safeway's California customer relations management files and compiled a list of people in California who had bought hummus of all things. You think they won't ask Barnes and Noble for a list of people who have purchased copies of 2600? The goons who are searching for hummus eaters will certainly find you. Think you have nothing to hide? Then you'll have no problem with letting them in when they show up at your door after the 4th Amendment has been legislated away!
You've probably got a big red flag next to your name in a number of databases. But maybe you can repair the damage. I suggest you get your CC out right now and use it to buy 50 copies of "A Charge To Keep". This will prove to the Attorney General that you're one of the sheep who won't cause any trouble and who deserves to keep his citizenship after PATRIOT II passes.
Next time you buy 2600, make sure you've got your tinfoil hat on first!
I used to be a Sun Java Architect and I worked on both internal and external projects on both Solaris and Windows. I posted a lot of bug reports myself, and got some of those "will not fix" replies.
My company sells an AWT-based scientific application (don't laugh, it was started in 1998 and now we're the leader in our market). We had a problem with scroll bars suddenly blinking when we ran under 1.4 on Windows. You'd scroll down, and then you couldn't concentrate on what you were reading because the scroll bar thumb started blinking endlessly. It was really annoying and everyone in QA filed a bug report as soon as they saw it.
I found the bug in Sun's bug database (which seems to be down at the moment because all my searches come up empty). Other people were complaining about it, but Sun decided it was "not a bug" and it got marked with "Will Not Fix". Apparently some engineer there had an old dusty copy of the Microsoft Visual C++ glossary, which claimed that a scrollbar should indicate that it has focus by blinking its scrollbar thumb. They claimed this is standard Windows behavior. Someone asked for an example of a Windows application that does this, and the engineer responded that Microsoft's crash diagnostic tool, "Dr. Watson", has a scrollbar that blinks when it has focus.
So while you're trying to concentrate on what you're reading in the viewport, the thumb blinks and blinks close nearby, constantly reminding you that it has input focus in case you forget. But as you can imagine, your typical user is familiar with Dr. Watson and uses it every day! Just think of all the confusion and terror that would result if the application behavior were inconsistent with Dr. Watson.
We "solved" the problem by making all scrollbars unfocusable. I think Sun has been laying off too many people.
I posted a couple of days ago complaining about just this in the case of the for(String s: c) idiom and a couple of other such things in 1.5.
for(String s: c) is syntactic sugar. The compiler changes it into normal syntax on one of its sweeps, and the JVM never sees it. It does mean, however, that code using it needs to be compiled with a 1.5 compiler.
But they've been doing this for a long time. The 1.1 compiler introduced inner classes (which are practically unusable with any of the 1.1 compilers anyway because they are all so easily confused by legal inner class syntax). For syntactic sugar, they introduced class literals, e.g. "String.class" which is sugar for Class.forName("java.lang.String"). If you're using Retroguard to obfuscate your JAR in your build script, class literals are poison because they hardcode the class name.
If the history of inner classes serves as a guide, you'd have to be crazy to use generics in the 1.5 release. The compiler bugs surrounding them probably won't go away until 1.6.
I understand the problem with SPAM, but why a legal solution to a technical problem?
Because it's not a technical problem- it's a social problem that happens to involve technology. I suppose the phone company should come up with technical method to stop telemarketers as well, but the failure of technical solutions in solving the telemarketer problem was what prompted the creation of the do-not-call list. Technical solutions to spam have so far been a failure as well. The most you can hope for is a perpetual arms race.
It reminds me of the litgation induced from "deep linking," when in reality the web master simply needs to better configure his/her server.
That's a case of corporate idiots bursting onto the scene and applying political and legal pressure to destroy the protocols that made the web successful, because they want to shape it into something that favors their own myopic interests, and they think they can spend the money to get the courts to back them with a poorly reasoned decision. The fact that there's a technical solution to what they're whining about is convenient but irrelevant. Even if there weren't a technical solution to prevent deep linking, their case would be bankrupt.
Similarly there are technical solutions to this. If I'm on a "do-not-email" list, then why don't I configure my email client to only accept emails within my address book? Many email clients can do this filtering, even web based ones, so what's the problem? Effectively, this is what these people want and there's a solution so why the red tape?
Because we shouldn't have to resort to whitelists. I cannot compile a list of everyone in the world who isn't an asshole and who I might want to get email from. Maybe you never get mail except from six people, but some of us have to distribute our contact information.
Your first link (the "drowning") has an inflammatory headline "Intercepted call linked Saddam to al-Qa'ida terror cell" but nowhere in the article does it actually document any linkage between Saddam's regime and Al-Quaeda at all. Some guy in northern Iraq made a phone call to someone else in Al-Quaeda. While this is interesting, it's irrelevant because northern Iraq isn't under Saddam's control. (Also, it's questionable whether a phone call is worth going to war over.)
The nypost.com link contains this link to Saddam:
The United States has extensive proof of communication between Iraqi officials and an al Qaeda-affiliated group - but has been reluctant to reveal the information because of its sources, The Post has learned. A stream of intelligence links Saddam Hussein's government to Ansar al Islam, which wants a Taliban-style government in Kurdish northern Iraq, sources said.
Translation: We have proof, trust us! This is an assertion, not evidence, and as assertions go, it's a pretty farfetched one. Why would Saddam be colluding with people who want an Islamic government in Northern Iraq? The administration has been making lots of noise out of Iraqi links to Al Quaeda, but they always fail to emphasize that these are links from Northern Iraq which is not under Saddam's control. Links to northern Iraq are irrelevant to a decision of war on the south.
Your iraqwatch.com link dates from September 2002. Although the president made an issue of the aluminum tubes in his State of the Union speech, this was debunked by the International Atomic Energy Agency. And it takes more than aluminum tubes to make nuclear weapons. Aluminum tubes are useful for lots of things. If I buy a spark plug, it doesn't mean I have a tank. If you think aluminum tubes are worth starting a war over, you've taken leave of your senses.
Concerns about fossil fuel emissions? This is the madman who set oil wells on fire at the end of the Gulf War which burned for many months (years?) spewing black smoke into the atmosphere.
You seem to implicitly assume that I'm more concerned about fossil fuel emmissions than you are. But if this guy set oil wells on fire at the end of the last war, what makes you think he wouldn't set them on fire at the beginning of this one?
Oh, "supporting terrorism." On that question the U.S. is lying. They have shown no evidence.
What they have shown is that he has some chemical or biological agents (although far less than he had in 1991-1998). That is not the same thing as "supporting terrorism", which is rhetorical nonsense.
We, on the other hand, have so many chemical and biological agents ourselves that we can't even keep them from getting into the mail.
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Uh, Radiation?
You don't need air to "carry heat away"
Radiative transfer is proportional to delta T ^4
But it's not as efficient as conduction and convection until you reach temperatures that are way too hot for a chip.
It would be just like operating a CPU without a heat sink, except that the chip wouldn't also be receiving thermal radiation from other objects in the room.
Of fucking course all orbits are planar, and you don't need Kepler's frickin' laws to prove it, just the fact that the only data defined in a planetary orbit are a point (center) and a vector (the velocity of the object) attached to the second point. All you can define with a point and a line in 3d space is a plane, hence orbits have to be planar.
You left out the acceleration, and the requirement that the force on the planet needs to be a central force from your origin where r=0.
Dark matter comes in two varieties: "cold dark matter" and "hot dark matter". Neutrinos are examples of "hot" dark matter because their speeds are close to c.
The observed mass distributions of galaxies implies that there is some stuff that gathers in clumps to form walls, voids, etc. So it must be "cold", because if it were composed of "hot" fast-moving particles, these structures would have dissipated by now.
Neutrinos contribute to the overall mass of the universe (if they have mass), but they have been ruled out as cold dark matter candidates.
A 'Hello World' applet run using appletviewer. Ok cpu usage is at 0.0% which is to be expected since the applet doesn't do anything once it's painted the display, but look at RSIZE. 13.4M.
Yeah, that's the VM overhead, so?
And you can expect that number to blow out pretty quickly as the code is extended to make it do something useful.
I assume that adding features in your favorite language actually causes memory use to shrink?
Hello World in C has a resident size of 304K. Granted that's just using printf to output to a console but it's still a dramatic difference.
Actually, 304K seems like a hell of a lot of memory to lose for a Hello World in C.
You might want to take a look at "rotovator" systems, which rely on reaction mass from the ground (or on momentum transfers from rocks in space being lowered to Earth) to keep them in orbit, but which therefore don't need to be tethered to the ground and so don't need to be in a geosynchronous orbit. You spin the entire rotovator in such a way that its tips come to a brief stop in the atmosphere for payloads to be attached, and counterintuitively this allows the rotovator to be much shorter, lighter, and less stressed than a geosynchronous elevator would be. Geosynchronous beanstalks on Earth pretty much require supermaterials like buckytubes; you might be able to pull off a rotovator with Kevlar.
I was thinking of something similar... geosynchronous orbits are too far away to be practical. The earth just doesn't spin fast enough.
Instead we might have a space station (at a higher orbit than the silly ISS) lower a fishing line down just to the edge of the atmosphere. A small rocket could deliver a payload just high enough to reach the grappling hook, and then the space station would reel the payload in. This way, the rocket delivering the payload doesn't have to supply it with its orbital momentum; that comes from the orbiting satellite.
Of course both these ideas (space elevator or otherwise) require some massive object in a stable orbit around the earth, and that would be really expensive to set up even if it's just a space rock.
OK, first some clarification. This is the original AC post that I replied to originally:
Your understanding is wrong. A geosynchronous orbit is merely one which orbits such that it is always above a fixed point on the earth's surface.
(Which is wrong, this is a definition of a geostationary orbit like you said.)
There are 3 competing designs for a geosynchronous space elevator- the "tower" (CM lower than geosync orbit), the "rope" (CM higher than geosync orbit), and the "zeppelin" (CM exactly at geosync orbit).
The tower requires support from the ground. The rope requires a tether to the ground. Only the zeppelin requires no coupling to the ground, which means it can use a non-geostationary orbit, but it's the least stable design since as soon as you get on it, rockets have to start firing at the top for the system to maintain itself in its position.
I guess the rope and tower could both be supported by a ship in the ocean that moved around in a figure 8 forever, but it would be much more practical to use a geostationary orbit in both cases. (Not that the word "practical" has any place at all in this discussion.)
Pipes. The space elevator is a thin carbon nano-tube ribbon, you can't pump anything up it. And the pipes would need a weight to length ratio of roughly the same (7.5kg per km) and have a massive tensile strength since the weight of that 'weightless' hydrazine would be massive.
:) ).
You wouldn't pump the hydrazine up through the nanotubes. That would be silly. You wouldn't have a simple hose connected to the length of the elevator either, because the mgh pressure at the bottom would be ridiculous. Getting fluid of any sort up there would require a sort of active transport system, like a mechanized bucket brigade. Which is similar to how water systems in skyscrapers work. This requirement can be met by simply having the passengers take the hydrazine up there with them.
Although I think you recognize that I was simplifying for the sake of argument.
You would need to also maintain the CM at exactly geosynch at all times, not correct afterwards, since then you would need to deal with intertia of the cable falling to earth, and you are essentially lifting 20 tonnes via conventional rockets plus a nice 35,000+ km cable, somewhat inefficient (some would say stupid, but not me
Keeping the CM just slightly outside geosync at all times would be best.
Second, with the ground based anchor, contrary to popular misconceptions the centre of mass is always EXACTLY at geosynch
Actually, with a ground based anchor, the center of mass is only microns away from the center of the earth! Although your observation that the CM is orbiting geosynchronously is still correct, since it still moves around the center once per day in a tiny little circle down there.
No kidding. Did you see this little gem in the New York Sun?
Yes, you're right, I was thinking of a geostationary orbit because it's a requirement for a space elevator.
I can imagine a 100,000km elevator coiled up in the australian desert, then a shuttle launched with it tied to the back. The huge coil slowly unwinds, only to be dragged across Australia, levelling perth!
And in the end, the damn rabbits just dig holes right underneath it anyway.
If they're able to produce a rod of this stuff even six feet long that retained those physical properties, I'd be more willing to believe it.
But perhaps just as importantly, the bottom of a geosynchronous elevator design needs to touch the ground because it needs the base to be pulling down on it, not lifting up. If you want to take a 20 ton payload up the elevator without pulling it down, then the elevator is going to need to be under at least 20 tons of tension at the ground when there is no payload on it.
Naah, not necessarily.
Say (for simplicity of argument) we have a free-floating design, with a basket hanging a few feet off the ground. In equilibrium, the center of mass of the entire elevator (basket, cable, counterweight) is in geosynchronous orbit.
You put a 20 ton payload into the basket. This shifts the CM downward by an amount. So you pump (weightless) hydrazine up the elevator to corrective rockets sitting on the counterweight, and the rockets push the CM back up into geosynchrous orbit. They do this by pushing the counterweight into a realm above geosync orbit where it experiences a centrifugal force of 20 tons in the upward direction, and this equilibrates with the 20 tons pulling down on the ground. Of course the centrifugal force isn't a "real" force, it's really just an artifact of inertial effects within a rotating coordinate system.
Once the CM is in stable orbit again it doesn't matter what you do with forces internal to the orbiting assembly, i.e. between the counterweight and the basket. Pulling the basket up to the level of the counterweight won't alter the CM placement. (Although sideways Coriolis forces on the rising 20 tons will start complicating things on the way up.) Still, the amount of rocket fuel spent raising the payload into orbit this way is much less than with a conventional rocket.
Your design is slightly different in that you have the CM sitting outside geosynchronous orbit in the realm where it experiences the outward centrifugal force all the time. So you've got the other end attached to the ground, pulling up on it. This is conceptually a little bit simpler to grasp, but it puts increased tension in the cable, and after lifting a certain amount of stuff into orbit, the CM of the system will reach geosynchronous orbit anyway- and all the tension at the ground will be gone.
Your understanding is wrong. A geosynchronous orbit is merely one which orbits such that it is always above a fixed point on the earth's surface.
Seems that his understanding is right on target. Your definition is correct, but a moment of thought should be all you need to realize that no geosynchronous orbit can exist where this "fixed point" is not on the equator. Otherwise the orbit doesn't conserve angular momentum. Can you imagine a geosynchronous orbit over the North Pole for example? How would that work?
All geosynchronous satellites occupy positions in the same orbital path, which forms a ring in the plane of the earth's equator.
There's no reason (in theory) why the bottom has to be anchored to the ground (although it probably would have to be to reduce tension on the elevator material). Ideally the elevator could be set up so that the bottom would hang a few feet off the ground in midair.
There's also no reason why the top would "lag behind a bit". In fact the orbital speed of the counterweight will tend to increase, not decrease, if the orbit decays below geosynchronous orbit. So it would tend to lag forward, not behind. It would definitely need a transport system to carry rocket fuel up to the counterweight for corrective thrust.
The real reason why one hasn't been built is the extreme material strength required. Nobody has yet developed a material that can hang suspended for a length of 30,000 miles without breaking. This is why most designs count on the bottom of the elevator touching the ground, so that a significant portion of the elevator's weight can be supported by contact with the earth instead of tension in the elevator. Another mitigating factor is the weightlessness of the material at high altitudes- the parts up near the counterweight hardly contribute any tension at all and can be built especially thick. Even with these two caveats, the required tensile strength is so high that people still talk about exotic materials like buckytubes and single-crystal metals whenever the topic of the space elevator comes up. Without some breakthrough in materials engineering, the project is essentially hopeless.
I can't find one without those pesky Windows keys, for example.
I work with a guy whose keyboard seems to have been designed by an AOL user interface expert. It has FOUR Windows keys! One between each Alt and Ctrl, plus two more under "Insert" and "Page Down"! (Of course it has the rubber chiclet "buy overpriced crap" keys running across the top as well.) He hates it and I keep telling him to get a new one. Trying to do any work on it is difficult, because if you hit one of the Windows keys the Start menu comes up and steals focus. It's like typing on a minefield.
The Windows key is the most useless key on the keyboard. Although it does come in handy in some cases, like when you want to break loose from a full screen demo in a Radio Shack store display.
Calm down, it was a joke. Apparently you missed my point.
I agree with you on this point, but then I sit back and think about it: Am I really that interesting?
I've decided that although personal privacy and freedom are very important, if some weirdo (capitol or otherwise) really wants to see what kinda of pr0n I look at or wants to listen in on my phone conversations (which almost always consist of "So, Starbucks or cyber cafe first?"), let them. Maybe they will get some sort of insight that in general, people aren't worth listening to.
People who smoke marijuana tend not to be very interesting either. They make silly observations that they mistake for profound insights. They're preoccupied with chips and chocolate. They keep forgetting what they were talking about.
And yet the nation's prisons are packed with them, so clearly someone is interested.
If you're going to do a DoS attack, at least do it right, with an army of infected machines taking orders from you over IRC. Even a script kiddie knows you don't hammer away at someone from your own IP using a browser and an HTML frameset. Being charged as a cyberterrorist for doing something like that would generally be considered extremely lame.
Also, the situation on the other end isn't necessarily what you think it is. The URL often doesn't point to the spammer's own server. Spammers have nothing of any worth to sell themselves, so they approach stupid small businesses like pornographers, credit services, etc. The sales pitch is that the spammer is selling web page hits, not emails, and they only have to pay for actual page loads to their site. So he makes a fraction of a penny off them every time a request hits the server with his URL parameter attached. You should at least remove all URL parameters so that nobody profits from your DOS attack.
You'd have to be out of your mind to buy a copy of 2600 with a credit card. Are you oblivious to the digital slime trail that your daily activities are leaving behind you? How many lists do you think you're on?
Some idiots in the government recently examined all of Safeway's California customer relations management files and compiled a list of people in California who had bought hummus of all things. You think they won't ask Barnes and Noble for a list of people who have purchased copies of 2600? The goons who are searching for hummus eaters will certainly find you. Think you have nothing to hide? Then you'll have no problem with letting them in when they show up at your door after the 4th Amendment has been legislated away!
You've probably got a big red flag next to your name in a number of databases. But maybe you can repair the damage. I suggest you get your CC out right now and use it to buy 50 copies of "A Charge To Keep". This will prove to the Attorney General that you're one of the sheep who won't cause any trouble and who deserves to keep his citizenship after PATRIOT II passes.
Next time you buy 2600, make sure you've got your tinfoil hat on first!
I used to be a Sun Java Architect and I worked on both internal and external projects on both Solaris and Windows. I posted a lot of bug reports myself, and got some of those "will not fix" replies.
My company sells an AWT-based scientific application (don't laugh, it was started in 1998 and now we're the leader in our market). We had a problem with scroll bars suddenly blinking when we ran under 1.4 on Windows. You'd scroll down, and then you couldn't concentrate on what you were reading because the scroll bar thumb started blinking endlessly. It was really annoying and everyone in QA filed a bug report as soon as they saw it.
I found the bug in Sun's bug database (which seems to be down at the moment because all my searches come up empty). Other people were complaining about it, but Sun decided it was "not a bug" and it got marked with "Will Not Fix". Apparently some engineer there had an old dusty copy of the Microsoft Visual C++ glossary, which claimed that a scrollbar should indicate that it has focus by blinking its scrollbar thumb. They claimed this is standard Windows behavior. Someone asked for an example of a Windows application that does this, and the engineer responded that Microsoft's crash diagnostic tool, "Dr. Watson", has a scrollbar that blinks when it has focus.
So while you're trying to concentrate on what you're reading in the viewport, the thumb blinks and blinks close nearby, constantly reminding you that it has input focus in case you forget. But as you can imagine, your typical user is familiar with Dr. Watson and uses it every day! Just think of all the confusion and terror that would result if the application behavior were inconsistent with Dr. Watson.
We "solved" the problem by making all scrollbars unfocusable. I think Sun has been laying off too many people.
I posted a couple of days ago complaining about just this in the case of the for(String s: c) idiom and a couple of other such things in 1.5.
for(String s: c) is syntactic sugar. The compiler changes it into normal syntax on one of its sweeps, and the JVM never sees it. It does mean, however, that code using it needs to be compiled with a 1.5 compiler.
But they've been doing this for a long time. The 1.1 compiler introduced inner classes (which are practically unusable with any of the 1.1 compilers anyway because they are all so easily confused by legal inner class syntax). For syntactic sugar, they introduced class literals, e.g. "String.class" which is sugar for Class.forName("java.lang.String"). If you're using Retroguard to obfuscate your JAR in your build script, class literals are poison because they hardcode the class name.
If the history of inner classes serves as a guide, you'd have to be crazy to use generics in the 1.5 release. The compiler bugs surrounding them probably won't go away until 1.6.
I understand the problem with SPAM, but why a legal solution to a technical problem?
Because it's not a technical problem- it's a social problem that happens to involve technology. I suppose the phone company should come up with technical method to stop telemarketers as well, but the failure of technical solutions in solving the telemarketer problem was what prompted the creation of the do-not-call list. Technical solutions to spam have so far been a failure as well. The most you can hope for is a perpetual arms race.
It reminds me of the litgation induced from "deep linking," when in reality the web master simply needs to better configure his/her server.
That's a case of corporate idiots bursting onto the scene and applying political and legal pressure to destroy the protocols that made the web successful, because they want to shape it into something that favors their own myopic interests, and they think they can spend the money to get the courts to back them with a poorly reasoned decision. The fact that there's a technical solution to what they're whining about is convenient but irrelevant. Even if there weren't a technical solution to prevent deep linking, their case would be bankrupt.
Similarly there are technical solutions to this. If I'm on a "do-not-email" list, then why don't I configure my email client to only accept emails within my address book? Many email clients can do this filtering, even web based ones, so what's the problem? Effectively, this is what these people want and there's a solution so why the red tape?
Because we shouldn't have to resort to whitelists. I cannot compile a list of everyone in the world who isn't an asshole and who I might want to get email from. Maybe you never get mail except from six people, but some of us have to distribute our contact information.
Your first link (the "drowning") has an inflammatory headline "Intercepted call linked Saddam to al-Qa'ida terror cell" but nowhere in the article does it actually document any linkage between Saddam's regime and Al-Quaeda at all. Some guy in northern Iraq made a phone call to someone else in Al-Quaeda. While this is interesting, it's irrelevant because northern Iraq isn't under Saddam's control. (Also, it's questionable whether a phone call is worth going to war over.)
The nypost.com link contains this link to Saddam:
The United States has extensive proof of communication between Iraqi officials and an al Qaeda-affiliated group - but has been reluctant to reveal the information because of its sources, The Post has learned.
A stream of intelligence links Saddam Hussein's government to Ansar al Islam, which wants a Taliban-style government in Kurdish northern Iraq, sources said.
Translation: We have proof, trust us! This is an assertion, not evidence, and as assertions go, it's a pretty farfetched one. Why would Saddam be colluding with people who want an Islamic government in Northern Iraq? The administration has been making lots of noise out of Iraqi links to Al Quaeda, but they always fail to emphasize that these are links from Northern Iraq which is not under Saddam's control. Links to northern Iraq are irrelevant to a decision of war on the south.
Your iraqwatch.com link dates from September 2002. Although the president made an issue of the aluminum tubes in his State of the Union speech, this was debunked by the International Atomic Energy Agency. And it takes more than aluminum tubes to make nuclear weapons. Aluminum tubes are useful for lots of things. If I buy a spark plug, it doesn't mean I have a tank. If you think aluminum tubes are worth starting a war over, you've taken leave of your senses.
Concerns about fossil fuel emissions? This is the madman who set oil wells on fire at the end of the Gulf War which burned for many months (years?) spewing black smoke into the atmosphere.
You seem to implicitly assume that I'm more concerned about fossil fuel emmissions than you are. But if this guy set oil wells on fire at the end of the last war, what makes you think he wouldn't set them on fire at the beginning of this one?
Oh, "supporting terrorism." On that question the U.S. is lying. They have shown no evidence.
What they have shown is that he has some chemical or biological agents (although far less than he had in 1991-1998). That is not the same thing as "supporting terrorism", which is rhetorical nonsense.
We, on the other hand, have so many chemical and biological agents ourselves that we can't even keep them from getting into the mail.
You either don't believe the US or you don't believe Saddam. You can't have it both ways.
You mean I have to believe that one or the other is telling the truth? What if they're both liars?
>>Sure, he invented C, but is he curently trying to gain any segway into the Lunix market?
>You know, just because it's slashdot doesn't mean every single article must somehow be related to linux.
Or the Segway, for that matter. I'm getting tired of this subliminal guerilla marketing!