>a rocket works in space because the expanding gas exterts more pressure on the aft-facing components of the engine (including other gasses) than the bow facing ones.
aaaaaaaaarrrrggggggghhhh!!!!!!!!! no no no no NO!!!
the gun does move backwards, but it's not about "pushing". this is a subtlety important in space, where people sometimes think "how can a rocket work when there's no air to push against?".
if you have an object made of two parts (e.g 'gun and bullet' or 'rocket and exhaust gas') which is initially stationary, then if one part moves forwards, the other part MUST move backwards to conserve linear momentum.
actually centrifugal force is fine since the principle of relativity means that any accelerating frame can be described as a stationary frame in a gravitational field.
in this problem you should apply conservation of momentum like I did in my reply, not forces.
there is no acceleration except the instantaneous acceleration when firing. the projectile and cannon will then move with constant speeds in opposite directions, not with accelerations.
momentum will be conserved, so if the cannon is 100 times heavier than the projectile, the recoil speed of the cannon will be 1/100th the speed of the projectile.
since you have to get this cannon into space, making it heavy isn't a great idea, but I expect you can probably just give the projectile a small velocity and let gravity do its thing.
it's not just a case of general relativity allowing black holes, but actually making them happen.
the idea of black holes has been around for ages. people thought what would happen if loads of mass collapsed to a single point. but they thought it would never actually happen because this would require a perfectly symmetric mass distribution. if it wasn't perfectly symmetric i.e. slightly distorted, then as it collapsed these distortions would get bigger and the matter wouldn't collapse to a single point.
but general relativity changes this. it predicts that any body with a quadrupole moment will emit gravitational waves. spherically symmetric bodies don't have quadrupole moments, but distorted ones do. so if the collapsing matter is distorted, it will emit gravitational waves, and this will make the collapsing matter more symmetric. in this way gravitational waves act like a correction make black holes "generic" i.e. ANY large enough body collapsing WILL form a black hole whether it's perfectly symmetric or not.
MS: okay, we've just made a new educational office suite. all the business tools/server parts have been removed. our Sugested Retail Price is 1million, so I guess 100 licenses* will cover that fine.
*only 1 CD, no manual. Do not make illegal copies of the CD.
you take keep saying "current physics still says faster-than-light TRAVEL is impossible".
I'm trying to tell you you are wrong. it does not say that, you are vastly oversimplifying it. I've just given you an explanation why, but you keep saying it!
the only way you could be right is if you're using "travel" in the sense of "go on holiday". that IS NOT a scientific defintion, and thus "physics" wouldn't say that.
I'm a physicist, you're not, so where the fuck do you get off telling me or anyone else what physics says!?
is your other hobby trying to explain what the law really says to judges?
well I don't agree with the idea of "speech crime", but neither do I believe free speech should be absolute, maybe this is inconsistent by your definitions?
for me it's simply a case of -absolute free speech means no censorship -censorship is often necessary -therefore there should not be absolute free speech
I think people should just accept free speech isn't and shouldn't be absolute and accept it. I think there are lots of "think of the children"-fundamentalists who want to make things "absolute" e.g. abortion is ALWAYS wrong/speech should ALWAYS be free, but imo that's just stupid.
valid points though I'm not sure what your argument is.
if you're saying that "free speech is still an absolute because I can describe those things in other ways", then you're wrong because either way speech WILL ultimately be censored.
if you're just saying that in these cases censorship is a secondary effect and it's not "censorship for its own sake" then I agree.
because they are predicted by general relativity, so if they don't exist there must be something very wrong with general relativity.
also, many explanations of observations rely on them, such as active galactic nuclei (AGN). these are very bright galaxies, emitting ridiculous amounts of energy. black holes explain them perfectly, so if we don't have black holes we have a very big problem of what's causing all this radiation.
black holes are actually the most efficient "engines" known, far more efficient that nuclear fusion that powers the Sun and maybe one day our power stations.
it's not MY understanding of US law that I'm worried about;-)
e.g. many Americans point to the 2nd ammendment as an absolute argument against gun-control, conveniently ignoring the parts about "well-regulated" and "milita being needed".
1. "our" understanding is that any massive particle travelling at less than the speed of light (in a vacuum) cannot be accelerated up to the speed of light. [it is possible (but AFAIK all attempts to detect have given a null result) that faster-than-light particles (tachyons) exist, but they would be created with speeds > light in the first place.]
2. in certain x-ray experiments you can have x-rays for which both the phase and group speeds are greater than the speed of light. however, they are highly dispersive and so cannot be used for communications. hence the more accurate version of your statement is "information cannot travel faster than the speed of light".
3. in the quantum-mechanical view, light travels from A to B with all speeds and along all paths, however the different paths interfere destructively such that the most probable path by far is in a straight line at speed c. the effect of these different paths is seen in interference experiments, most famously Young's double-slit experiment.
no I didn't see that particular story, I guess I was too busy actually *doing* physics.
dark matter isn't actually the basis of many theories (or at least not any good ones), it itself is a theory to account for observations.
Slashdot Mirror
I use (a)MSN and it has the option that no-one can contact me unless I've already got them on my list.
worked perfectly so far.
>a rocket works in space because the expanding gas exterts more pressure on the aft-facing components of the engine (including other gasses) than the bow facing ones.
aaaaaaaaarrrrggggggghhhh!!!!!!!!! no no no no NO!!!
the gun does move backwards, but it's not about "pushing". this is a subtlety important in space, where people sometimes think "how can a rocket work when there's no air to push against?".
if you have an object made of two parts (e.g 'gun and bullet' or 'rocket and exhaust gas') which is initially stationary, then if one part moves forwards, the other part MUST move backwards to conserve linear momentum.
yes, but that's a "controlled burn", not an "explosion" (hopefully)
it's not the explosion pushing the gun backwards, it's conservation of linear momentum.
if you could have an explosion that was only forwards, you'd still get recoil.
actually centrifugal force is fine since the principle of relativity means that any accelerating frame can be described as a stationary frame in a gravitational field.
Sigh, a-little-knowledge-can-be-dangerous-physics...
in this problem you should apply conservation of momentum like I did in my reply, not forces.
there is no acceleration except the instantaneous acceleration when firing. the projectile and cannon will then move with constant speeds in opposite directions, not with accelerations.
momentum will be conserved, so if the cannon is 100 times heavier than the projectile, the recoil speed of the cannon will be 1/100th the speed of the projectile.
since you have to get this cannon into space, making it heavy isn't a great idea, but I expect you can probably just give the projectile a small velocity and let gravity do its thing.
it's not just a case of general relativity allowing black holes, but actually making them happen.
the idea of black holes has been around for ages. people thought what would happen if loads of mass collapsed to a single point. but they thought it would never actually happen because this would require a perfectly symmetric mass distribution. if it wasn't perfectly symmetric i.e. slightly distorted, then as it collapsed these distortions would get bigger and the matter wouldn't collapse to a single point.
but general relativity changes this. it predicts that any body with a quadrupole moment will emit gravitational waves. spherically symmetric bodies don't have quadrupole moments, but distorted ones do. so if the collapsing matter is distorted, it will emit gravitational waves, and this will make the collapsing matter more symmetric. in this way gravitational waves act like a correction make black holes "generic" i.e. ANY large enough body collapsing WILL form a black hole whether it's perfectly symmetric or not.
the difference being "80" is not a word, or even an abbreviation of a word, or even a letter replacing a word.
what you find easy to read isn't the same for anyone. since the apostrophe is incorrect, it slows me down a little while I "error-correct".
i's thi's ea'sier to read?
yeah but your point is valid.
imagine...
Judge: you are hereby fined $100million
MS: okay, we've just made a new educational office suite. all the business tools/server parts have been removed. our Sugested Retail Price is 1million, so I guess 100 licenses* will cover that fine.
*only 1 CD, no manual. Do not make illegal copies of the CD.
> "OUR CURRENT UNDERSTANDING OF physics says that faster than light travel is impossible"
is the complete quote.
that's still wrong though noobie.
>Why are you posting with "No Karma Bonus" checked?
because the whole point of karma bonus is to get good posts seen. I don't think this argument is composed of good posts.
"physics also says that faster than light travel is impossible."
"current physics still says faster-than-light TRAVEL is impossible."
"At NO STAGE did I say that FTL Travel is impossible."
---
"you are a comple fuckwit by nature."
"Grow up, you little twerp."
attitude like yours are what piss off scientists.
you take keep saying "current physics still says faster-than-light TRAVEL is impossible".
I'm trying to tell you you are wrong. it does not say that, you are vastly oversimplifying it. I've just given you an explanation why, but you keep saying it!
the only way you could be right is if you're using "travel" in the sense of "go on holiday". that IS NOT a scientific defintion, and thus "physics" wouldn't say that.
I'm a physicist, you're not, so where the fuck do you get off telling me or anyone else what physics says!?
is your other hobby trying to explain what the law really says to judges?
well I don't agree with the idea of "speech crime", but neither do I believe free speech should be absolute, maybe this is inconsistent by your definitions?
for me it's simply a case of
-absolute free speech means no censorship
-censorship is often necessary
-therefore there should not be absolute free speech
I think people should just accept free speech isn't and shouldn't be absolute and accept it. I think there are lots of "think of the children"-fundamentalists who want to make things "absolute" e.g. abortion is ALWAYS wrong/speech should ALWAYS be free, but imo that's just stupid.
valid points though I'm not sure what your argument is.
if you're saying that "free speech is still an absolute because I can describe those things in other ways", then you're wrong because either way speech WILL ultimately be censored.
if you're just saying that in these cases censorship is a secondary effect and it's not "censorship for its own sake" then I agree.
I don't really care about the 1st ammendment, it's the principle of free speech as an absolute, which is what Freenet IS based on, which I don't like.
because they are predicted by general relativity, so if they don't exist there must be something very wrong with general relativity.
also, many explanations of observations rely on them, such as active galactic nuclei (AGN). these are very bright galaxies, emitting ridiculous amounts of energy. black holes explain them perfectly, so if we don't have black holes we have a very big problem of what's causing all this radiation.
black holes are actually the most efficient "engines" known, far more efficient that nuclear fusion that powers the Sun and maybe one day our power stations.
lots of times, here's two easy ones:
1. libel/slander
2. harrassment/threats
it's not MY understanding of US law that I'm worried about ;-)
e.g. many Americans point to the 2nd ammendment as an absolute argument against gun-control, conveniently ignoring the parts about "well-regulated" and "milita being needed".
you are simply wrong.
1. "our" understanding is that any massive particle travelling at less than the speed of light (in a vacuum) cannot be accelerated up to the speed of light. [it is possible (but AFAIK all attempts to detect have given a null result) that faster-than-light particles (tachyons) exist, but they would be created with speeds > light in the first place.]
2. in certain x-ray experiments you can have x-rays for which both the phase and group speeds are greater than the speed of light. however, they are highly dispersive and so cannot be used for communications. hence the more accurate version of your statement is "information cannot travel faster than the speed of light".
3. in the quantum-mechanical view, light travels from A to B with all speeds and along all paths, however the different paths interfere destructively such that the most probable path by far is in a straight line at speed c. the effect of these different paths is seen in interference experiments, most famously Young's double-slit experiment.
no I didn't see that particular story, I guess I was too busy actually *doing* physics.
dark matter isn't actually the basis of many theories (or at least not any good ones), it itself is a theory to account for observations.
maybe flamebait (especially to constitution-loving USians) but I don't believe in freedom of speech as an absolute right.
there are many times when it should be, and is, censored.
like the other reply says, NOBODY who knows anything about black holes doubts they exist.
in fact, if they DIDN'T exist we'd be totally screwed.
it's a shame this "interest" you speak of is totally divorced from "understanding", or at least in your case.
> It is fairly obvious to most people that if everybody respects property rights, everybody prospers.
B.S. this means the rich prosper.
If everyone respected PEOPLE, then everybody prospers.
"workers" *are* low-skill labour.
skilled people are called "assistants" or "employees" or "administrators" or "managers" or...