UmbralRaptor changed the topic of #kspacademia to: https://gist.github.com/pdn4kd/164b9b85435d87afbec0c3a7e69d3e6d | Dogs are cats. Spiders are cat interferometers. | Космизм сегодня! | Document well, for tomorrow you may get mauled by a ネコバス. | <UmbralRaptor> … one of the other grad students just compared me to nomal O_o | <ferram4> I shall beat my problems to death with an engineer.
<bofh>
whitequark: so basically what happened was a hydrogen BLEVE at some absurd PSI, it seems
<bofh>
jesus fuck
<bofh>
also I like how there was somehow NO PRESSURE RELIEF VALVE ON THE REACTOR
<bofh>
"...called a 'Phosgene Shed'..."
<bofh>
"...a total of ONE KILOGRAM OF PHOSGENE had been released to the atmosphere..."
<whitequark>
that's actually way better than it could have been
<whitequark>
imagine if the valve was left open
<whitequark>
you'd have one ton of phosgene
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<egg|zzz|egg>
!wpn whitequark's cat
* Qboid
gives whitequark's cat a triangulation
<egg|zzz|egg>
!wpn whitequark
* Qboid
gives whitequark a greening keyboard
<egg|zzz|egg>
!wpn bofh
* Qboid
gives bofh a variable with a set attachment
* egg|zzz|egg
zzz
<egg|zzz|egg>
goodnight
<bofh>
whitequark: jesus fuck
<bofh>
whitequark: well we already saw what happened in 1924 Germany
<whitequark>
bofh: actually, the same thing happened in 1947 in texas
<whitequark>
it was the 4th largest non-nuclear explosion in human history
<whitequark>
(or maybe 2nd largest, depending on how you count)
<whitequark>
and the largest unintentional one
<bofh>
wow looking at the MSDS for methyl mercaptan
<whitequark>
you think they shut down the plant? no. they called firemen, who started to POKE THE PIPE WITH A SHARP STICK
<UmbralRaptor>
AAAAAAΑΑA
<whitequark>
when the leak worsened, the firemen decided to USE HIGH-PRESSURE WATER TO STRIP INSULATION FROM THE PIPE SO THAT THE LEAK BECOMES MORE APPARENT
<whitequark>
they also managed to inadvertently trap one of the firemen inside a fire engine surrounded by a massive hydrocarbon cloud, that ignited
<whitequark>
(he ran away and escaped unscathed)
<whitequark>
oh and the pipe hasn't been changed since 1976. it was inspected in 2002 and recommended for replacement since it was thinning by that point but... no one did that
<bofh>
whitequark: WHAT. WHAT
<bofh>
WHAT
<bofh>
ARE THESE FIREMEN STARK-RAVING MAD?!?
<whitequark>
the other meaning of "fireman"
<bofh>
the Ancient Rome meaning
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<bofh>
whitequark: wow somehow they all survived despite being trapped in the fireball.
<egg|zzz|egg>
UmbralRaptor: I'm surprised that it be that and not 20.000000298023223876953125 %
<egg|zzz|egg>
!wpn UmbralRaptor
* Qboid
gives UmbralRaptor a skew catenoid
<egg|zzz|egg>
kitty?
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<egg|zzz|egg>
whitequark: I'm confused by this plaquenil discussion; if the cat had somehow gone out of its way to import malaria from somewhere in the region, wouldn't it likely be chloroquine-resistant anyway?
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<whitequark>
that's not about malaria
<whitequark>
but about bartonella
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<egg|phone|egg>
Ah
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<egg|work|egg>
!wpn bofh, UmbralRaptor, whitequark, et al.
* Qboid
gives bofh, UmbralRaptor, whitequark, et al. a fancy soliton-like mutex
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<egg|work|egg>
!tell bofh so I think if t is a trivector and b is a bivector, the product tb is the vector defined by ⟨tb, w⟩ = ⟨t, b∧w⟩ for all vectors w?
<Qboid>
egg|work|egg: I'll redirect this as soon as they are around.
<bofh>
whitequark: COMBUSTIBLE IRON DUST HOLY FUCK
<Qboid>
bofh: egg|work|egg left a message for you in #kspacademia [20.06.2017 09:57:00]: "so I think if t is a trivector and b is a bivector, the product tb is the vector defined by ⟨tb, w⟩ = ⟨t, b∧w⟩ for all vectors w?"
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<bofh>
I *think* so? Se.
<bofh>
Sec*
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<egg|nomz|egg>
bofh: oh I found the video where they scale up a 1 l reactor to 10 kl
<egg|nomz|egg>
*boggle*
<bofh>
egg|nomz|egg: yeah, that's the MCMT one. with the reaction of "let's mix hydrocarbons with molten sodium in a vessel that has no pressure release, oh btw did I mention the reaction releases hydrogen gas and is a runaway exotherm?"
<egg|nomz|egg>
bofh: well it did have some sort of emergency pressure release rupture disc thing that blew 10 s before the eggsplosion
egg|nomz|egg is now known as egg
<bofh>
egg: why the hell did it take that long to blow?
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<egg>
bofh: eggstremely evil idea: overload unary operator* on multivectors to represent the Hodge star :D
<kmath>
YouTube - Fresh flexy gears, the world is depressing, let's solder LEDs @scanlime-in-progress
<bofh>
"Acute Health Effects: Ingestion: Low acute toxicity. Ingestion is a minor route of entry for intended use of this product." from the MSDS for an HP LaserJet toner cartridge.
<egg>
bofh: :D
<FluffyFoxeh>
hehe
<bofh>
egg: hey that lets me implement Maxwell's Equations very simply so you should do it!
<egg>
bofh: hmm how so?
<egg>
bofh: (I emphatically don't have the Hodge star in my libs, to do something non-orientation-preserving you have to go through .coordinates() because that's evil)
<egg>
bofh: which adds to why *bivector being the hodge star would be evil, it's unconspicuous (mix it with pointers to vectors or optional vectors and you've got a really silly trap :-p)
<Qboid>
egg meant to say: bofh: (I emphatically don't have the Hodge star in my libs, to do something orientation-dependent you have to go through .coordinates() because that's evil)
<egg>
bofh: oh, with the eleggtromagnetic tensor?
<egg>
bofh: yeah, my libs don't do relativity though, Vector is 3-dimensional :_p
<egg>
bofh: if I did do relativity I'd need to distinguish linear forms and vectors... the type structure would get really tricky :D
<egg>
bofh: Principia is a classical physics lib (and KSP mod), I guess eventually I could make a mod called Feldgleichungen :D
<bofh>
damnit implement Minkowski space already
<bofh>
:P
<bofh>
LOL
<egg>
bofh: but yeah, in classical physics you don't really have a reason to be orientation-dependent
<bofh>
Okay, point.
<egg>
bofh: I have to admit I don't understand that fancy formulation of Maxwell's equation (but then do I understand the usual one anyway, cf recent xkcd?), I guess the fact that it's a Hodge star on moar dimensions means the same concerns don't apply?
<egg>
even with relativity you shouldn't be orientation-dependent, right? (otoh something something something CPT if you do QFT)
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<egg>
dF=0 <<< how the hell are you hiding Maxwell in there >_>
<bofh>
math.stanford.edu/~conrad/diffgeomPage/handouts/maxwell.pdf or users.aims.ac.za/~solomon/akason.pdf for a bit more in-depth/elementary treatment
<egg>
bofh: nah, I mean, I can see why it happens, but still it feels odd to have them fit on half a line :-p
<bofh>
dF=0 is equivalent to d_sB = 0 and d_sE + \partial_0 B = 0, where d_s is the spatial exterior derivative
<bofh>
true :P
<bofh>
(and you can do the rest from definition of exterior derivative, I'm not writing it out :P)
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<egg>
bofh: also, on the subject of pedestrian classical physics, it is very odd to see the elementary stuff that's always done with cross products written rigourously with respect to orientation-independence
<bofh>
the Hodge star gives you the inhomogeneous version of the above
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<bofh>
(in the sense that we take the Hodge dual of F, compute its exterior derivative and then Hodge-star back and set that equal to our charge terms)
<bofh>
egg: oh? example?
<egg>
written out in the Principia codebase there's the Coriolis acceleration, gimme a minute; I was working out the vector between the closest points of two lines defined by four points, that one involves trivector*bivector :D (not typed/implemented yet)
<egg>
those * are the action of bivectors on vectors, you'd write that as cross
<egg>
other crosses (not in this file), those that give you the Ωs, are |Wedge|s
<egg>
bofh: and so you get some crosses that turn into something that's morally like a multiplication (and in that code looks like one, same operator), others that turn into something much fancier
<bofh>
ahhhhhhh
<bofh>
Nice.
<bofh>
Very nice.
<egg>
bofh: lemme unfold the paper in my back pocket, I have the vector between the closest points of two lines defined by four points, it's cute
<bofh>
ooh, nice. do scan/retype plz :P
<egg>
you have a line through K and C, and a line through Q1 and Q2; the shortest vector from KC to Q1Q2 (this is obviously orientation independent) is [sound of egg typing]
<egg>
((Q2-K)∧(C-K)∧(Q2-Q1))((C-K)∧(Q2-Q1))
<egg>
――――――――――――――――――――――――――――――――――――――
<egg>
⟨(C-K)∧(Q2-Q1),(C-K)∧(Q2-Q1)⟩
<egg>
bofh: ^
<egg>
(yes the bottom is a squared norm, but I wrote an inner product because I was taking care throughout the calculations never to take a norm
<egg>
)
<egg>
bofh: the multiplication at the top is between a trivector and a bivector, quite plainly, I think that can justifiably be written as an actual multiplication (and thus operator* in the principia libs), but I'm not sure
<egg>
hmm, it does seem fishy to write it as multiplication
<egg>
I can't find a case where both associations are correct and are different, but there are cases where it doesn't associate with the other multiplications
<egg>
let t be a trivector, b a bivector, v a vector, t(bv) is defined, (tb)v is not
<egg>
and t(bv) = (tb)∧v
<egg>
similarly if w is a vector, (tv)w is defined, t(vw) is not, and (tv)w = t(v∧w)
<egg>
bofh: so the multiplication of a trivector with a bivector or vector isn't a multiplication; what is it then :-p
<Iskierka>
so I forgot to put the accelerometer in the picar, and had to fudge around for like 40 minutes getting it in
<Iskierka>
I peek though and realise SCL/SDA are swapped compared to how I thought
<Iskierka>
:V
<egg>
bofh: I like how I'm figuring things out about what should be elementary properties of multivectors in 3d not by studying algebra but by doing geometry with my strongly-typed lib
<bofh>
Ooh, sec.
<bofh>
Also, no, that makes perfect sense. Geometry > algebraic bashing
<bofh>
22:05:35 <@egg> bofh: so the multiplication of a trivector with a bivector or vector isn't a multiplication; what is it then :-p
<bofh>
weird
<egg>
bofh: hey, algebraic bashing is fun too :-p
<egg>
I miss math lectures
<bofh>
> algebraic bashing is fun too :-p
<bofh>
we are no longer on speaking terms :P
<egg>
:-p
<egg>
something something Bourbaki
<bofh>
on a serious note, it amuses me to what lengths I went to avoid algebraic tedium in my complex analysis class
<bofh>
often this involved bootstrapping a theorem beyond the scope of the course and then just using it as an all-purpose hammer.
<egg>
hah
<bofh>
and like, complex analysis is sufficiently nice that this works amazingly well.
<egg>
complex analysis *is* nice
<egg>
bofh: but tbh had I not undergone a fair amount of algebraic bashing I wouldn't even have realized the need to distinguish all those fancy multivectors and why bivectors multiply vectors, and principia's geometry lib would be a sad place :-p
<egg>
(otoh they currently have a bug! trivector * bivector and trivector * vector aren't multiplications!)
<egg>
bofh: ah, the Hodge star not breaking all the things wrt orientation is probably because the symmetric bilinear form has signature -1
<egg>
(on the Maxwell stuff)
<egg>
whereas if you have an inner product, the Hodge star wrt *that* is evil
<egg>
also 4 being even
<egg>
re. trivector*bivector and trivector*vector, this probably has to do with the geometric product, I had been trying to avoid having to understand that >_>
<egg>
(it seems to associate with wedge of all things?)