
should have asked him why ice is slippy - then maybe he'd have explained how magnets work
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Fri 23 Sep 2011, 21:36,
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and frankly the best answer i can give is "they just fucking DO all right?" i could bang on about magnetic fields just being electric fields under a lorentz boost, but that just bounces the question onto "how the fuck does an electric field work?", to which my response is "they just fucking DO all right?" (or banging on about the exchange of virtual photons between electrons and protons, which helps no-one)
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Fri 23 Sep 2011, 21:31,
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Little bastards swan around for FIFTY FUCKING YEARS pretending to be totally massless but, oh no, the hussies were hiding little pot bellies. Less than an electron volt between the three of them but oh, that's enough. Enough for them to change flavour between the Sun and the Earth. Filthy liars. FILTHY TRANSGENDER FUCKING LIARS. And suddenly the Standard Model's dead, isn't it? Little fucking bastards. Fucking shitty bints. And now we find that there are probably STERILE FUCKING NEUTRINOS polluting everything! Fucking shitty massive sterile neutrinos. CUNTS. At least one species of them. Perhaps more. FUCKING SHITTY CUNTS.
And now. Oh, NOW! Breaking the speed limit, are they? While being fucking massive?
WHO THE FUCK DO THEY THINK THEY ARE?
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Fri 23 Sep 2011, 21:41,
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And now. Oh, NOW! Breaking the speed limit, are they? While being fucking massive?
WHO THE FUCK DO THEY THINK THEY ARE?

and has yet to complete peer review. Probably just some factor they didn't take into account during the experiment that buggered up readings.
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Fri 23 Sep 2011, 21:45,
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The stuff about sterile neutrinos is still only suggestive, too. The rest of it's true -- neutrinos have a small, but non-zero mass (or, at least, the sum of the masses of the three types of neutrino is non-zero so *at least one type of neutrino* has a mass), and that fucks up the standard model right away. This is a good thing because it means we may all still be employed in twenty years time. Well, those of us who are physicists, anyway.
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Fri 23 Sep 2011, 21:50,
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you can pretend you believed in string theory all along.
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Fri 23 Sep 2011, 22:15,
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I'd be more convinced of someone finding a way of showing it from standard QM field theory. There's actually no requirement for a massless quantum particle to travel at the speed of light - that's a classical notion. (And there isn't even the requirement in general relativity for massless particles to travel at the speed of light except over very small distances, but that's getting very fiddly pedantic.) Of course, doing that might be a lot trickier. Me, I just work in classical physics at the minute so I'll leave that to everyone else :)
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Fri 23 Sep 2011, 22:33,
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don't give a shit
it's like "LOL RULES"
"LOL, CALL THAT A MASS"
and they just stick their fingers up and are all BLBMLMGLGMLGMLG!!
I bet they get pissed up and do freaky orbits around themselves just because it's mental
/hasn't got a shitting clue about physics blog
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Fri 23 Sep 2011, 21:45,
archived)
it's like "LOL RULES"
"LOL, CALL THAT A MASS"
and they just stick their fingers up and are all BLBMLMGLGMLGMLG!!
I bet they get pissed up and do freaky orbits around themselves just because it's mental
/hasn't got a shitting clue about physics blog

Billions at a time. No idea at all. And Chuck Norris can't catch them.
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Fri 23 Sep 2011, 21:48,
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Fri 23 Sep 2011, 21:50,
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Fucking neutrinos. I'll give them fucking "radiative species". CUNTS.
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Fri 23 Sep 2011, 21:50,
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And how do we make antigravity? (that's antigravity, not auntie gravy tea)
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Fri 23 Sep 2011, 21:43,
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/random childhood memory
edit: also, she had a habit of calling any soft drink pop
fucking hell, crap orange diluted, it's not pop.
/random childhood trauma
( ,
Fri 23 Sep 2011, 21:45,
archived)
edit: also, she had a habit of calling any soft drink pop
fucking hell, crap orange diluted, it's not pop.
/random childhood trauma

At macroscopic scales, by which I mean about 10 micrometres and above, gravity is from all experiment and appearances a fictional force. A fictional force is one that imparts the same acceleration on everything -- the most commonly-encountered example is centrifugal force which, no matter what your high-school physics teacher told you, most definitely exists. It's just that it only exists in a rotating frame of reference. Next time you go around a corner in a car, watch your pen and your wallet on the dashboard, if you're silly enough to put them there. They go skittering across at exactly the same rate (as would you if you weren't belted in). Centrifugal force is a fake force, which manifests in a non-trivial frame of reference. And if you remember simple experiments, a pebble and a lead weight fall at the same speed... gravity is totally fictional.
If you follow this through, it's pretty quick to find that gravity can only be explained (*assuming that space and time are both continuous*) as a manifestation of spacetime curvature. A mass distorts the spacetime around it, changing the path that a freely-moving body experiences. So what to us feels like being pressed down to Earth is just our bodies attempting to move in a straight line that happens to be towards the centre of the Earth -- the same as when a train starts movign before you've sat down, you go flying towards the back of the carriage.
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Fri 23 Sep 2011, 21:49,
archived)
If you follow this through, it's pretty quick to find that gravity can only be explained (*assuming that space and time are both continuous*) as a manifestation of spacetime curvature. A mass distorts the spacetime around it, changing the path that a freely-moving body experiences. So what to us feels like being pressed down to Earth is just our bodies attempting to move in a straight line that happens to be towards the centre of the Earth -- the same as when a train starts movign before you've sat down, you go flying towards the back of the carriage.

If by "magic" you mean "differential geometry and clear physical reasoning".
I realised I forgot to say about anti-gravity. If you can find me a type of fluid that has a very negative pressure, I can give you anti-gravity. Otherwise you'd have to find me some gravitons with an opposite "charge", and I'm not entirely sure I could formulate a sensible theory of gravity that included them.
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Fri 23 Sep 2011, 21:55,
archived)
I realised I forgot to say about anti-gravity. If you can find me a type of fluid that has a very negative pressure, I can give you anti-gravity. Otherwise you'd have to find me some gravitons with an opposite "charge", and I'm not entirely sure I could formulate a sensible theory of gravity that included them.

I know a few people who work at CERN. They're way better at particle physics than I'll ever be.
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Fri 23 Sep 2011, 21:53,
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why does space have three dimensions?
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Fri 23 Sep 2011, 21:57,
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which contains half the chemicals required for the reaction. (Which requires an input of heat, which is why you had to drag old-style matches across a rough surface - the friction put heat into the match head and started the reaction.)
2) Tricky. Basically, because it does. If you believe in string theory it actually has about 10 of the fuckers, but we can only access three, because we are, for more or less accidental reasons, stuck onto a 3d sheet hanging in 10d space. There are also apparently various theorems in differential geometry that only really work very well in 3 spatial (and 1 temporal) dimensions but I don't know about that. Also, neither gravity nor chemistry wouldn't work very well in 2d, and more than 3 is a bit wasteful. My guess is that that's the best answer.
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Fri 23 Sep 2011, 22:00,
archived)
2) Tricky. Basically, because it does. If you believe in string theory it actually has about 10 of the fuckers, but we can only access three, because we are, for more or less accidental reasons, stuck onto a 3d sheet hanging in 10d space. There are also apparently various theorems in differential geometry that only really work very well in 3 spatial (and 1 temporal) dimensions but I don't know about that. Also, neither gravity nor chemistry wouldn't work very well in 2d, and more than 3 is a bit wasteful. My guess is that that's the best answer.

it seems a bit too convoluted too me
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Fri 23 Sep 2011, 22:03,
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I agree. It's worse than that, too. String theory is all well and good, but it's "background dependant", which means that if I want to be in vacuum I put that in by hand, while if I want to be near a planet i have to put *that* in by hand. That's a total deal-breaker for a theory of gravity. Ever since general relativity we've grown accustomed to theories of gravity that are "background-independant" -- when the theory itself can determine the nature of the spacetime around it.
For me that's extremely important. Why replace something that works with something that, no disrespect meant, doesn't?
Worse than that, even, is that there are, as yet, zero testable predictions from string theory. One of the only reliable predictions a string theorist has ever made is that there are ten to the motherfucking 150 or more valid vacua. This is rather euphemistically known as the "string landscape". In other worlds it's known as "having your cake and eating 10 to the fucking 150 times as much as you have". It's no wonder string theory can reproduce (at a perturbative - ie, incomplete and unsatisfactory, level) the standard model of particle physics plus gravity, if it can also reproduce ten to the fucking 150 other universes.
Put another way, modern physics is built on symmetries. The standard model is something like U(1)xSU(2)xSO(3) or something like that; I forget. Different string theories use different groups, but the most common that I'm aware of is entertainingly known as "heterotic" string theory - E8xE8. E8 is a group that contains U(1)xSU(2)xSO(3), and much more, inside it. So if you square the fucker of course you'll find the symmetries of the real unvierse in it. And plenty besides.
Basically, it's a theory with zero predictive power. Mathematically it's really very beautiful, and even aesthetically it's very nice - even from a physical point of view. It's a lovely idea, taking a vacuum background and having different vibrations on some strings giving us the whole of physics. But the way it's gone, it can explain anything you want it to - meaning that, beautiful maths or not, it's not physics.
At least, that's my opinion, but since i know very little more about string theory than you, it probably isn't worth all that much.
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Fri 23 Sep 2011, 22:10,
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For me that's extremely important. Why replace something that works with something that, no disrespect meant, doesn't?
Worse than that, even, is that there are, as yet, zero testable predictions from string theory. One of the only reliable predictions a string theorist has ever made is that there are ten to the motherfucking 150 or more valid vacua. This is rather euphemistically known as the "string landscape". In other worlds it's known as "having your cake and eating 10 to the fucking 150 times as much as you have". It's no wonder string theory can reproduce (at a perturbative - ie, incomplete and unsatisfactory, level) the standard model of particle physics plus gravity, if it can also reproduce ten to the fucking 150 other universes.
Put another way, modern physics is built on symmetries. The standard model is something like U(1)xSU(2)xSO(3) or something like that; I forget. Different string theories use different groups, but the most common that I'm aware of is entertainingly known as "heterotic" string theory - E8xE8. E8 is a group that contains U(1)xSU(2)xSO(3), and much more, inside it. So if you square the fucker of course you'll find the symmetries of the real unvierse in it. And plenty besides.
Basically, it's a theory with zero predictive power. Mathematically it's really very beautiful, and even aesthetically it's very nice - even from a physical point of view. It's a lovely idea, taking a vacuum background and having different vibrations on some strings giving us the whole of physics. But the way it's gone, it can explain anything you want it to - meaning that, beautiful maths or not, it's not physics.
At least, that's my opinion, but since i know very little more about string theory than you, it probably isn't worth all that much.

I do get the impression I'm being trolled a bit, but I like mouthing off about it because I've been mildly irritated by string theorists (and supersymmetry people) for a good few years now :)
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Fri 23 Sep 2011, 22:28,
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Brian cox annoys me more though, saying the heat death of the universe is how the universe WILL end as fact, when there are so many unanswered questions.
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Fri 23 Sep 2011, 22:42,
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I've spent a lot of my career looking at the assumptions of cosmology. Basically we assume
* gravity is metric
* the universe is homogeneous and isotropic on average
* the theory of gravity is general relativity
assumption (1) is more or less safe, on the scales we're working on. assumption (3) may as well be kept for the minute because we've got nothing that good to replace it with, although there are plenty of things done in cosmology to do with this. assumption (2) is simply downright wrong. firstly, "on average" is meaningless without defining an average... and we can't do that in general relativity. (well, we may finally be able to, but the jury's still currently out and in any event no work has been done on it.) secondly, while the universe "on average" may be both homogeneous and isotropic, it certainly isn't locally, or we wouldn't exist and neither would the planet, the suns, the galaxy, the local group, the local cluster or even the local supercluster. pretending that all that doesn't exist was a superb approximation for a very long time but observation is now finally catching up with theory in cosmology... and it may well be breaking down.
or it may not. that's the joy of unanswered questions. the standard model of cosmology might be totally right, as unpleasant a prospect as that seems. or it might be very wrong.
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Fri 23 Sep 2011, 22:49,
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* gravity is metric
* the universe is homogeneous and isotropic on average
* the theory of gravity is general relativity
assumption (1) is more or less safe, on the scales we're working on. assumption (3) may as well be kept for the minute because we've got nothing that good to replace it with, although there are plenty of things done in cosmology to do with this. assumption (2) is simply downright wrong. firstly, "on average" is meaningless without defining an average... and we can't do that in general relativity. (well, we may finally be able to, but the jury's still currently out and in any event no work has been done on it.) secondly, while the universe "on average" may be both homogeneous and isotropic, it certainly isn't locally, or we wouldn't exist and neither would the planet, the suns, the galaxy, the local group, the local cluster or even the local supercluster. pretending that all that doesn't exist was a superb approximation for a very long time but observation is now finally catching up with theory in cosmology... and it may well be breaking down.
or it may not. that's the joy of unanswered questions. the standard model of cosmology might be totally right, as unpleasant a prospect as that seems. or it might be very wrong.

whether or not everything will just decay away and we'll be left with absolute nothingness, i mean we haven't seen a proton decay
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Fri 23 Sep 2011, 23:27,
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that was implicitly contained in the "standard model of the universe" bit. for that to happen, the standard model of cosmology has to be more or less accurate. (it probably is, to be honest, but there are plenty of loopholes and things that simply don't seem to make total sense.) basically the idea is that everything will end up with radiation - in the end stars will have processed almost everything that can be processed and black holes swallowed everything else and the few things left over will have decayed, and then eventually the black holes themselves will decay in hawking radiation. it seems very possible that every fundamental particle is unstable, and most if not all theories that combine the strong and electroweak forces predict that; i'm willing to believe it, to be honest, although the half-lives may be of the order of tens of billions of years, or more. given a standard cosmology, and all of that, the "heat death" seems inevitable. unless you can find a way of changing the laws of thermodynamics, and of gravity, it's hard to avoid.
except that the standard model of cosmology may be quite wrong. we may not even understand hawking radiation, although we may observe an analogue of it in the next year or two. (any quantum radiation from any kind of horizon will go a long way to justifying the argument for hawking radiation - although naturally it won't prove it. there are groups have now made acoustic black holes, which are like real black holes but for sound waves, and in a couple of years we should be in a position to measure the hawking radiation, if it exists. i'll be stunned if it doesn't.) fundamental particles may not decay. like you say, proton decay has never been observed. the universe might collapse on itself. physics we have absolutely no idea about could come into force when the universe grows too big - or if it contracts to too small a scale. the whole thing could be based on physics that is accurate on local scales but applied very badly on cosmological scales.
my view is that all bets are off in cosmology right now. at the heart of it, we don't understand what's going on - just how it looks when we interpret it using a particular model. there's a fuckload of observational support for that model, but even so... it's just a model. phenomenology, to use the jargon.
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Fri 23 Sep 2011, 23:41,
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except that the standard model of cosmology may be quite wrong. we may not even understand hawking radiation, although we may observe an analogue of it in the next year or two. (any quantum radiation from any kind of horizon will go a long way to justifying the argument for hawking radiation - although naturally it won't prove it. there are groups have now made acoustic black holes, which are like real black holes but for sound waves, and in a couple of years we should be in a position to measure the hawking radiation, if it exists. i'll be stunned if it doesn't.) fundamental particles may not decay. like you say, proton decay has never been observed. the universe might collapse on itself. physics we have absolutely no idea about could come into force when the universe grows too big - or if it contracts to too small a scale. the whole thing could be based on physics that is accurate on local scales but applied very badly on cosmological scales.
my view is that all bets are off in cosmology right now. at the heart of it, we don't understand what's going on - just how it looks when we interpret it using a particular model. there's a fuckload of observational support for that model, but even so... it's just a model. phenomenology, to use the jargon.

in case anyone wanted MORE walls of text from me tonight (i think i'm now on a dozen ignore lists), this is where penrose's recent news stories have come from. penrose has a theory, which hasn't been satisfactorily published but which actually is quite elegant in principle, where you map the heat death of the universe onto the start of another. the details are a bit... detailed, but it boils down to looping future infinity onto past infinity, and being able to do so because the only things left in the universe are photons which for some reason i've never understood because he's not written a proper paper about this that i've ever seen means that there's no firm definitions of distance. so the massive distances at the end of the universe apparently can be mapped onto tiny distances in the very early universe. the heat death leads to a new big bang, new universes, and yet more physicists to evolve and ask WHAT THE FUCK HAPPENED TO THE ENTROPY?
oh, and also for respected physicists to work it out and then put out ill-advised papers based on statistics they readily admit they don't understand, which promptly get rubbished by the rest of the community.
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Fri 23 Sep 2011, 23:47,
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oh, and also for respected physicists to work it out and then put out ill-advised papers based on statistics they readily admit they don't understand, which promptly get rubbished by the rest of the community.

i could probably explain all this a bit more comprehensibly
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Fri 23 Sep 2011, 23:49,
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They never actually explained where the concentric rings were meant to have come from, and they used some really weird statistics where they compared everything with white noise rather than with simulated maps. That's like looking for discrepancies in a recording of a Beatles track by comparing it with white noise rather than a reasonably precise cover version. Or like looking for yellow blocks in a field of blue instead of a field of random colour. The papers were not well received - which isn't entirely Penrose's fault; he's never pretended to be an observational cosmologist nor a statistician.
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Fri 23 Sep 2011, 23:54,
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( , Fri 23 Sep 2011, 23:48, archived)

For us, it basically just means "everything", so by definition entropy can't come into it from outside, and neither can heat nor anything else. What we see might just be a tiny patch of it, but what we attempt to describe is everything. (We'd term something we can't see as "superhorizon" - our metaphors are still kind of stuck in the 15th century.) Cosmology depends on superhorizon scales, but you can get some seriously interesting stuff going on if you play around. Topology is a nice example. General relativity is lovely and all, but it says *nothing* about how the world looks as a whole; it's entirely possible that's doughnut shaped, or like a football, or like any crazy shape you can imagine, perhaps like a loaf of bread that someone drilled repeated holes into. Each model can easily describe our actual universe and all our observations, but each have extremely different behaviour.
So basically if you start taking stuff outside the observational universe seriously, a lot of things can happen.
Plus, I've never been able to draw horses :( I basically can't even draw :(
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Fri 23 Sep 2011, 23:58,
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So basically if you start taking stuff outside the observational universe seriously, a lot of things can happen.
Plus, I've never been able to draw horses :( I basically can't even draw :(

but i'm on b3ta quite a bit and normally willing to offer my opinionated opinions
edit: i also enjoy this kind of thing :)
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Sat 24 Sep 2011, 0:19,
archived)
edit: i also enjoy this kind of thing :)

Edit: i do have some questions about dark energy, but its too late
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Sat 24 Sep 2011, 0:30,
archived)


Here also is some magnet porn


each one of their virtual photons is encased in rubber before they exchange them
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Fri 23 Sep 2011, 21:37,
archived)

The Vatican informs me that even AIDS is small enough to slip through rubber johnnies. Lord alone knows how many photons get through.
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Fri 23 Sep 2011, 21:43,
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they also have to bombard them with unsealed photons.
WHERE WILL THE MADNESS END!
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Fri 23 Sep 2011, 21:47,
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WHERE WILL THE MADNESS END!

with the Vatican admitting that Irish priests molest their choirboys.
Unless it already has. In which case I take it back.
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Fri 23 Sep 2011, 21:51,
archived)
Unless it already has. In which case I take it back.

which is pretty serious I guess :)
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Fri 23 Sep 2011, 21:54,
archived)

I guess some top folkies there have had actual reports of everything that's been reported handed to them
no wonder they're pissed
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Fri 23 Sep 2011, 22:00,
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no wonder they're pissed