It must be something like that - they wouldn't be just scamming for grant money if something that obvious was wrong with the concept. I'd be excited if it could work - it seems so much more elegant than riding giant explosions to orbit.
assuming initial speed = 0 m/s, no lift (buoyant apogee) and a circular orbit (min axis = max axis):
Cd = coefficient of drag =.05 (conservative) T = thrust = 0.1 N (current ion engines) R = air density = 3.85 x 10^-3 kg/m^3 (record ballon altitude 40 km assuming standard atmosphere) A = cross sectional area = 10 m^2 (also conservative)
solving drag equation for terminal velocity yields:
V = SQRT( 2*T/(Cd*R*A) )
= 10 m/s, or about 20 mph
I think they'd have to get higher, otherwise the thing won't be able to get to an orbital velocity... it will just crawl along at the same altitude until it runs out of fuel and leaches He. I'm probably missing something (higher power engines or maybe the air density isn't realistic).
> but I don't see how you could get off the atmospheric "ground" with something > that can't overcome gravity. Even drag would be a problem for something that big > with that weak an engine.
> However, because a bouyant object doesn't have to "escape" until it is already > at the top of the atmosphere it's escape velocity would be much, much lower.
Man, I have to proof my posts. I meant why does buoyancy matter. Escape velocity should be around the same - the only thing that changes in the equation is the apparent radius of the planet, and not by much (1%).
My original skepticism was focused on whether or not an ion engine would work. The obvious advantage would be smaller balloons (ion engines have greater total impulse per pound) but I don't see how you could get off the atmospheric "ground" with something that can't overcome gravity. Even drag would be a problem for something that big with that weak an engine.
> You can get to escape velocity using an ion engine. Acceleration at.1g over a > long time gives the same final velocity as 3g for a short time. It adds up.
> What happened at Guantanamo? I have never heard of anything hapening there.
There is some coverage in the margins and in the liberal and alternative media.
> US Army and our country as a whole is not responsible here
I disagree. These actions were the predictable outcome of a war the US is waging. That includes the citizens who provide tacit and explicit support for a war (i.e. everyone). It's basic social psychology that abuse will escalate when third-party safeguards are not in place, no matter how righteous the jailkeepers are. The US insisted on invading Iraq without clear multilateral support. The US failed to provide the proper checks in the prisons. The US has argued for a loosening of civil rights and advocated torture in response to the threat of terrorism. (read the very public commentary on the subject starting from 9/2001 to before the Gitmo detainees were released several months ago).
> It sounds like, to me, that our government IS doing the right thing and IS > following the Geneva Convention.
There is also a misconception about what "begging the question means":) But I knew what you meant, so there's no need to be a pedant right? Right?
Escape velocity is wrong, I should have said orbital velocity as someone else pointed out. I'm really very sorry for that.
> Third, pushing "a big inflated condom" around in the upper atmosphere is not > really a problem since there isn't much air to create drag.
Whether or not this is possible with an ion engine is the question, and not an unreasonable one.
> Further, the higher you go, the less drag you feel
Is that what you just said? There may be a little drag, but an ion engine only produces a little force. How they compare is still a mystery to me.
Funny how whenever you ask a humble physics question, you always get people who condescend to your lack of precision in asking the question when often they know damn well what you're asking, and then they don't bother saying "I don't know" because that would be too damned easy.
> You are aware that there is no such thing as "escape velocity" when you are > bouyant, right? A more apt question is more can they reach orbital velocity
Can you really accelerate a big inflated condom to escape velocity with an ion drive? I mean, it can only get so high on He, and I'm assuming that at its apogee there will still be an appreciable amount of atmosphere. Would an ion drive be able to overcome the drag force? Anyone willing to do the math?
> The US (and most other nations) is a nation that obeys the Geneva Convention > Part of that is that deliberate attacks on civilian targets aren't allowed.
I understand that you are explaining a specific example of the hows and whys of the Geneva convention. However it should be pointed out that it is false that the US obeys the Geneva Convention.
The US evokes the Geneva Convention to give its populace a sense that it is acting morally when it is waging war. It's not even ostensibly true anymore that the US obeys the Geneva Convention, Abu Ghraib and Guantanamo being the most recent examples - in addition to the then-secret bombings of Cambodia and Laos and the attack on Panama being others - never mind war by proxy in greater Israel and Afghanistan, and passivity in the face of other human rights atrocities since the inception of the GC.
Given that the US doesn't even follow these rules, I don't see how it makes any sense to bother having a discussion about why the other guys should not use certain tactics. That being said, I don't see how it makes any sense to talk about rules, fairness, or morals on the battlefield. Once two groups decide to kill each other, all (or nothing) is fair.
> Unfair? No, never... > Some tactics are immoral, though.
So the tactics of the U.S. soldier are merely "unfair," while the tactics of the guerilla are "immoral?" What version of "fair" are you using to untangle morality from the definition?
The capabilities of the combatants may be different, but to imply that there is no moral equivalence is to again pretend that their is an element of fairness (aka justice) in warfare. And as you said, it doesn't come into play on the battlefield. Whether or not you are pro-war, once you decide for war - all soldiers are cold soldiers. If you accept that there is no fairness on the front, then there is no moral high ground to be had their either, and it is probably not in the interests of "victory" to pretend that there is.
I agree that the dangers are not necessarily than "conventional" power sources... just pointing out that fusion reactors are not something you'd want to build near a playground.
That being said, you're probably right that the grammar in gp implies that fusion is inherently more dangerous than a dirty fission reactor, which is nonsense as far as I know.
> COOLANT leaks would probably be a lot worse than reactant leaks
probably depends on the design. Does the JET coolant (initially He-4, I think) get a chance to become radioactive?
No, but his point is that there will likely be safety concerns for something churning out that much power (fires, reactant leaks), and there are still some radioactive contaminants to be dealt with (comparable to a "clean" fission reactor). Just because fusion is touted as a super-clean, perfect energy source doesn't make it so.
> Bikes are great. I used to ride 25ks into town every day to get to work before > they put the bus on thru here.
In some US locations it's dangerous to ride a bike because the roads are too busy/fast/bike-unfriendly. Drivers here (and maybe other places, I don't know) have a strange, adversarial relationship with cyclists and pedestrians - I dare say that some people seem to be aiming towards me out of frustration (I've been hit more than once - each time was the driver's fault). I've also had objects thrown at me (a large bottle, one time) and I can't count how many times I've been flipped off or yelled at for no reason other than that I was there.
Any cyclist or runner haters out there want to explain what annoys you so much about us? I'd really like to understand why you be hatin'.
> LOCK access for a given account after X consecutive failed logon attempts... > han Y accounts are locked for this reason in Z minutes, and as a community we'd > effectively end all dictionary attacks
The problem with this solution is that so-called "dictionary attacks" are virtually never carried out using the target's manual authentication mechanism, or even their enrcyption library functions (which are usually deliberately performance-crippled). Any brute-forcer worth its salt (heh) is run on a fast, private computer with an optimized hashing function on hash data that is pulled off of the target wholesale.
In addition to, and more important than, the methods you describe, users must use better passphrases, policies must be enforced, and the authentication schemes used must become more robust (larger key size, multi-layer security, OTP, etc).
> We cannot afford to be 'better' than our enemy as it is a huge weakness. > We must eliminate those who would do us harm...collateral damage or not.
Since its emergence as a military might, the US has used exactly the tactics you describe in many situations. The results in military win/loss terms have been mixed.
But purely military victories are not everything, and to think only in those terms is to grossly oversimplify global politics and foreign policy. In the long run, some of these "victories" have turned into huge defeats (the victory by proxy in Soviet-occupied Afghanistan, for instance). A subsequent increase in enemies abroad over the years has triggered a security situation, which has in turn been evoked repeatedly and compelled the citizens of the US to gradually abrogate many of the fundamental rights we once held dear.
> We must eliminate those who would do us harm...collateral damage or not.
Reaching moral equivalence with our enemies for the sake of merely beating them militarily is not worth it, especially when coupled with increased authoritarianism at home. Hopefully, the logic you use here becomes a marginal ideal - otherwise, very few people will be free and war and misery will become self-perpetuating constants.
> If you start killing tens of thousands of moderates to get a few bad guys the > moderates might get the idea that it is a far, far better thing for them to > take care of the bad guys than waiting for us to do it.
So let me get this straight - if a cop fails to keep murderers under control, then killing the cops will encourage them to do their job better?
That is the single most repugnant idea I've ever seen modded up here. Tubgirl trolls have nothing on you.
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It must be something like that - they wouldn't be just scamming for grant money if something that obvious was wrong with the concept. I'd be excited if it could work - it seems so much more elegant than riding giant explosions to orbit.
I came up with a similar result. Maybe we should just shut up and short the stock later on. :)
assuming initial speed = 0 m/s, no lift (buoyant apogee) and a circular orbit (min axis = max axis):
.05 (conservative)
Cd = coefficient of drag =
T = thrust = 0.1 N (current ion engines)
R = air density = 3.85 x 10^-3 kg/m^3 (record ballon altitude 40 km assuming standard atmosphere)
A = cross sectional area = 10 m^2 (also conservative)
solving drag equation for terminal velocity yields:
V = SQRT( 2*T/(Cd*R*A) )
= 10 m/s, or about 20 mph
I think they'd have to get higher, otherwise the thing won't be able to get to an orbital velocity... it will just crawl along at the same altitude until it runs out of fuel and leaches He. I'm probably missing something (higher power engines or maybe the air density isn't realistic).
> but I don't see how you could get off the atmospheric "ground" with something
> that can't overcome gravity. Even drag would be a problem for something that big > with that weak an engine.
correction - ONLY drag would be a problem.
> even in a gravity well? that doesn't seem right.
nevermind.
> However, because a bouyant object doesn't have to "escape" until it is already
> at the top of the atmosphere it's escape velocity would be much, much lower.
Man, I have to proof my posts. I meant why does buoyancy matter. Escape velocity should be around the same - the only thing that changes in the equation is the apparent radius of the planet, and not by much (1%).
My original skepticism was focused on whether or not an ion engine would work. The obvious advantage would be smaller balloons (ion engines have greater total impulse per pound) but I don't see how you could get off the atmospheric "ground" with something that can't overcome gravity. Even drag would be a problem for something that big with that weak an engine.
> You can get to escape velocity using an ion engine. Acceleration at .1g over a
> long time gives the same final velocity as 3g for a short time. It adds up.
even in a gravity well? that doesn't seem right.
> What happened at Guantanamo? I have never heard of anything hapening there.
There is some coverage in the margins and in the liberal and alternative media.
> US Army and our country as a whole is not responsible here
I disagree. These actions were the predictable outcome of a war the US is waging. That includes the citizens who provide tacit and explicit support for a war (i.e. everyone). It's basic social psychology that abuse will escalate when third-party safeguards are not in place, no matter how righteous the jailkeepers are. The US insisted on invading Iraq without clear multilateral support. The US failed to provide the proper checks in the prisons. The US has argued for a loosening of civil rights and advocated torture in response to the threat of terrorism. (read the very public commentary on the subject starting from 9/2001 to before the Gitmo detainees were released several months ago).
> It sounds like, to me, that our government IS doing the right thing and IS
> following the Geneva Convention.
Except when they aren't, which is often.
That is funny for so many reasons. Touche.
> Your question begs multiple misconceptions.
:) But I knew what you meant, so there's no need to be a pedant right? Right?
There is also a misconception about what "begging the question means"
Escape velocity is wrong, I should have said orbital velocity as someone else pointed out. I'm really very sorry for that.
> Third, pushing "a big inflated condom" around in the upper atmosphere is not
> really a problem since there isn't much air to create drag.
Whether or not this is possible with an ion engine is the question, and not an unreasonable one.
> Further, the higher you go, the less drag you feel
Is that what you just said? There may be a little drag, but an ion engine only produces a little force. How they compare is still a mystery to me.
Funny how whenever you ask a humble physics question, you always get people who condescend to your lack of precision in asking the question when often they know damn well what you're asking, and then they don't bother saying "I don't know" because that would be too damned easy.
> You are aware that there is no such thing as "escape velocity" when you are
> bouyant, right? A more apt question is more can they reach orbital velocity
Really? What's the difference?
I'm sure they have thought this out, but:
Can you really accelerate a big inflated condom to escape velocity with an ion drive? I mean, it can only get so high on He, and I'm assuming that at its apogee there will still be an appreciable amount of atmosphere. Would an ion drive be able to overcome the drag force? Anyone willing to do the math?
> The US (and most other nations) is a nation that obeys the Geneva Convention
> Part of that is that deliberate attacks on civilian targets aren't allowed.
I understand that you are explaining a specific example of the hows and whys of the Geneva convention. However it should be pointed out that it is false that the US obeys the Geneva Convention.
The US evokes the Geneva Convention to give its populace a sense that it is acting morally when it is waging war. It's not even ostensibly true anymore that the US obeys the Geneva Convention, Abu Ghraib and Guantanamo being the most recent examples - in addition to the then-secret bombings of Cambodia and Laos and the attack on Panama being others - never mind war by proxy in greater Israel and Afghanistan, and passivity in the face of other human rights atrocities since the inception of the GC.
Given that the US doesn't even follow these rules, I don't see how it makes any sense to bother having a discussion about why the other guys should not use certain tactics. That being said, I don't see how it makes any sense to talk about rules, fairness, or morals on the battlefield. Once two groups decide to kill each other, all (or nothing) is fair.
> Unfair? No, never...
> Some tactics are immoral, though.
So the tactics of the U.S. soldier are merely "unfair," while the tactics of the guerilla are "immoral?" What version of "fair" are you using to untangle morality from the definition?
The capabilities of the combatants may be different, but to imply that there is no moral equivalence is to again pretend that their is an element of fairness (aka justice) in warfare. And as you said, it doesn't come into play on the battlefield. Whether or not you are pro-war, once you decide for war - all soldiers are cold soldiers. If you accept that there is no fairness on the front, then there is no moral high ground to be had their either, and it is probably not in the interests of "victory" to pretend that there is.
If you needed video, why would you add latency with a router?
I agree that the dangers are not necessarily than "conventional" power sources... just pointing out that fusion reactors are not something you'd want to build near a playground.
That being said, you're probably right that the grammar in gp implies that fusion is inherently more dangerous than a dirty fission reactor, which is nonsense as far as I know.
> COOLANT leaks would probably be a lot worse than reactant leaks
probably depends on the design. Does the JET coolant (initially He-4, I think) get a chance to become radioactive?
No, but his point is that there will likely be safety concerns for something churning out that much power (fires, reactant leaks), and there are still some radioactive contaminants to be dealt with (comparable to a "clean" fission reactor). Just because fusion is touted as a super-clean, perfect energy source doesn't make it so.
> Bikes are great. I used to ride 25ks into town every day to get to work before
> they put the bus on thru here.
In some US locations it's dangerous to ride a bike because the roads are too busy/fast/bike-unfriendly. Drivers here (and maybe other places, I don't know) have a strange, adversarial relationship with cyclists and pedestrians - I dare say that some people seem to be aiming towards me out of frustration (I've been hit more than once - each time was the driver's fault). I've also had objects thrown at me (a large bottle, one time) and I can't count how many times I've been flipped off or yelled at for no reason other than that I was there.
Any cyclist or runner haters out there want to explain what annoys you so much about us? I'd really like to understand why you be hatin'.
> The number of times I've seen summer1 is ridiculous.
"coffee[1-9]" is another one. the best is when people pick embarrassing ones, like "imabadas", "jacked", or "bigman33".
> LOCK access for a given account after X consecutive failed logon attempts ...
> han Y accounts are locked for this reason in Z minutes, and as a community we'd
> effectively end all dictionary attacks
The problem with this solution is that so-called "dictionary attacks" are virtually never carried out using the target's manual authentication mechanism, or even their enrcyption library functions (which are usually deliberately performance-crippled). Any brute-forcer worth its salt (heh) is run on a fast, private computer with an optimized hashing function on hash data that is pulled off of the target wholesale.
In addition to, and more important than, the methods you describe, users must use better passphrases, policies must be enforced, and the authentication schemes used must become more robust (larger key size, multi-layer security, OTP, etc).
> We cannot afford to be 'better' than our enemy as it is a huge weakness.
> We must eliminate those who would do us harm...collateral damage or not.
Since its emergence as a military might, the US has used exactly the tactics you describe in many situations. The results in military win/loss terms have been mixed.
But purely military victories are not everything, and to think only in those terms is to grossly oversimplify global politics and foreign policy. In the long run, some of these "victories" have turned into huge defeats (the victory by proxy in Soviet-occupied Afghanistan, for instance). A subsequent increase in enemies abroad over the years has triggered a security situation, which has in turn been evoked repeatedly and compelled the citizens of the US to gradually abrogate many of the fundamental rights we once held dear.
> We must eliminate those who would do us harm...collateral damage or not.
Reaching moral equivalence with our enemies for the sake of merely beating them militarily is not worth it, especially when coupled with increased authoritarianism at home. Hopefully, the logic you use here becomes a marginal ideal - otherwise, very few people will be free and war and misery will become self-perpetuating constants.
> If you start killing tens of thousands of moderates to get a few bad guys the
> moderates might get the idea that it is a far, far better thing for them to
> take care of the bad guys than waiting for us to do it.
So let me get this straight - if a cop fails to keep murderers under control, then killing the cops will encourage them to do their job better?
That is the single most repugnant idea I've ever seen modded up here. Tubgirl trolls have nothing on you.
er, "your" thinking.
"There" includes "now." You can think otherwise, but that doesn't mean you're thinking makes any sense.
George Lucas to 1810c: I wish that I could just wish away my mistakes - but I can't.