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.
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<kmath>
<danlew42> Warning: looking at the Eclipse IDE for even a few seconds can cause permanent eye damage.
<bofh>
LOL
<bofh>
egglipse tomorrow it seems
<G-Mobile>
apparently balancing eggs during an eclipse is a thing
<G-Mobile>
supposedly the alignment with the moon adds tidal stability to the eggs so they'll balance easily
<Fiora>
lol
<G-Mobile>
it's a spinoff of the much less rational practice of balancing eggs on the /equinox/
<G-Mobile>
supposedly "something" about the equinox "does something" so the eggs will stand up all day
<Iskierka>
well I mean that is what's happening with tides
<Iskierka>
there is a non-zero effect
<Iskierka>
just not one that comes close to the effect of getting the yolk to sink and shift the egg's cg low enough to balance any time
<G-Mobile>
does it actually have a straightening factor or just net lightening?
<Iskierka>
(plus it wouldn't be all day, it'd be for high tides and that's it)
<Iskierka>
There is a gravity gradient that would cause a theoretical increased pull towards the top to increase stability
<Iskierka>
but good luck measuring its effect on any solid object
<Iskierka>
the only meaningful effect it has is how much of the harbor wall is wet
<G-Mobile>
also, there's a hidden assertion in the eclipse practice that being in the ecclipse totality means that the moon is directly above your position on the earth from the local perspective of a plane tangent to the earth at that location
<Iskierka>
but it has hours and quadrillions (guessing) of tonnes to act upon to make that happen
* Iskierka
stabs google results in the cubic kilometres
<G-Mobile>
in fact that's not true if you're not at a position that is near the moon's orbital plane, and then only if your location's total eclipse occurs at solar noon
<G-Mobile>
occurs during?
<Iskierka>
1332 quadrillion tonnes, if I figured that right
<G-Mobile>
coincides with
<Iskierka>
;wa 1.332e9 cubic kilometres * 1 kg/m^3 in tonnes
<kmath>
Iskierka: convert 1.332×10^9 km^3 (cubic kilometers)×1 kg/m^3 (kilogram per cubic meter) to metric tons: 1.332×10^15 t (metric tons)
<Iskierka>
;wa 1.332e9 cubic kilometres * 1 kg/cm^3 in tonnes
<kmath>
Iskierka: convert 1.332×10^9 km^3 (cubic kilometers)×1 kg/cm^3 (kilogram per cubic centimeter) to metric tons: 1.332×10^21 t (metric tons)
<G-Mobile>
if you're on the moon plane, at noon, and it's total eclipse, then the moon is actually very near directly overhead
<Iskierka>
and I'm too tired because those were both wrong
<G-Mobile>
otherwise the moon would not be aligned with gravity (oh wait, local gravity, fuck mountains)
<Iskierka>
but yes, it's 1332 quadrillion
<G-Mobile>
and if the moon isn't aligned with gravity, tidal force will actually be a net destabilizing force, though probably by sine error very near the least it can be
<Iskierka>
yeah local gravity may well be a bigger effect than the moon. Just the moon *isn't* quite zero effect
<Iskierka>
If the moon's alignment is not beyond the tipping point laterally it won't be destabilising, as it'll still be pointing up-ish
<G-Mobile>
so if you were at everest base camp, you might be able to balance an egg at an incredibly slight angle
<Iskierka>
but then that does imply an object that is stable to begin with
<Iskierka>
You have to define what the angle is at that point, however
<Iskierka>
because as far as you can measure, that's the angle that is flat, as that's the way gravity goes
<Iskierka>
and there isn't a horizon or such to go by
<G-Mobile>
this is too complicated, I give up, xenos paradox of complexity; you can't even balance eggs
<Iskierka>
you can if you just manipulate the conditions to make the yolk sink (or float, don't remember which) and move the cg such that it's inherently stable, as it's inside the radius
<X>
Anyone in totality?
<G-Mobile>
Nope. 80%
<SnoopJeDi>
I am, after 12 hrs of driving
<G-Mobile>
so's I'm playing in apple's graphing app, with sphere volume surface area ratios, and unless there's a technicality I've put them in right; and grapher is telling me that at about x=3, volume and surface area cross at y=114 and the sphere afterwards has more square units of surface than cubic units of volume; does that make sense somehow?
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<X>
/whois SnoopJeDi
<egg|work|egg>
!wpn Iskierka
* Qboid
gives Iskierka an overclocked µa741
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<kmath>
<spaceflashnews> Solar eclipse hunter Julio Vannini @ungaman is prepared and well equipped for today's event. #greatamericaneclipse… https://t.co/xzsWNZMSyt
<UmbralRaptor>
!wa 3^2*4*3.14159
<Qboid>
UmbralRaptor: 3^2×4×3.14159: 113.09724
<UmbralRaptor>
G-Mobile: the crossing point, yes. But for larger radii, there should be more "volume units" than "surface units"
<egg|work|egg>
!wpn UmbralRaptor
* Qboid
gives UmbralRaptor a decagon
TheKosmonaut is now known as ThePapanaut
<UmbralRaptor>
!wpn egg|work|egg
* Qboid
gives egg|work|egg a ligand-gated parabola with a hydrochlorofluorocarbon attachment
<egg|work|egg>
UmbralRaptor: we have passed P1 on the egglipse
<egg|work|egg>
wait I'm confused
<egg|work|egg>
!wa time UTC
<Qboid>
egg|work|egg: current time in UTC: 1:51:24 pm UTC | Monday, August 21, 2017
<egg|work|egg>
UmbralRaptor: you should write a test in Principia for the solar egglipses!
<egg|work|egg>
Contacts of UmbralRaptor with Earth
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* UmbralRaptor
is highly nonspherical!
<egg|work|egg>
bofh: a - sqrt(a**2-b**2) seems distinctly awful
<bofh>
yyyyyyyyyyyyyep that it is. since you magnify errors at each operation
<egg|work|egg>
bofh: yes, but I mean it's not nicely rewritable
<egg|work|egg>
(a-b)(a+b) in the root works, but the outer subtraction remains and stabs all your bits
<bofh>
I'm trying to think if there's a nice way (like, Aitken extrapolation-style) of rearranging the whole thing
<bofh>
also rofl at "stabs all your bits"
<egg|work|egg>
bofh: also heavens there's an "a" there, which can be expressed in 7 different ways in inputs, so given the ill-condition that formula has to be poked at 7 times D:
<egg|work|egg>
I basically tricked myself into writing a math library inside a single function didn't I
<bofh>
yyyyyyyyyyyyep nice job :P
<egg|work|egg>
bofh: and that's just the conic parameters
<egg|work|egg>
bofh: there's the anomalies and Kepler's equation at some point
<bofh>
Kepler's Equation is fairly nice numerically since all you're doing is root-finding on something well-behaved
<bofh>
the conic parameters in comparison are kind of disgusting numerically
<egg|work|egg>
bofh: "well-behaved"
<egg|work|egg>
bofh: there's a big nice cancellation following in there, applied after a nontrivial computation (the eccentric anomaly), right?
<egg|work|egg>
hm, but root finding, so maybe you're interested in the backward error?
<egg|work|egg>
blaaaaargh
<egg|work|egg>
aargh th
<bofh>
aarghth(x)
<egg|work|egg>
yup
<egg|work|egg>
gaaah I keep screwing up and replying directly instead of reply-
<egg|work|egg>
bofh: if you can make a good -sqrt you can use that easily, not sure how easy it is to make a 1-sqrt (assuming you don't go the whole way and find best polynomials for it, simply special-case around 1 and use some weird series or whatnot)
<egg|work|egg>
bofh: wait no, a 1-sqrt doesn't even save you, because its argument would absorb some rounding errors already
<bofh>
so sqrt(1+x) does have a nice power series
<egg|work|egg>
bofh: aha, but what about 1-sqrt(1-x)
<egg|work|egg>
wait no, even that would take a rounded arg, blaaaargh
<egg|work|egg>
UmbralRaptor: also, now we're past P1
<egg|work|egg>
next up is U1, when UmbralRaptor contacts the Earth!
<egg|work|egg>
in about 50 min
* SnoopJeDi
prays to the fluid dynamics gods
* egg|work|egg
summons ferram4
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UmbralRaptor is now known as PenumbralRaptor
<PenumbralRaptor>
(ignore that the egglipse doesn't start for another 30 or so minutes here.)
<Qboid>
egg|afk|egg meant to say: wait no, P1? I'm confused
<egg|afk|egg>
sorry, C1
<bofh>
egg|work|egg: if sqrt(1+x) has a nice power series then generally sqrt(1-x) does too (I guess I forgot to indicate radius of convergence: it's 1)
<egg|afk|egg>
bofh: ok, so anyway the point is to get a well-conditioned thing, because you have to feed in rounded stuff
<egg|afk|egg>
bofh: amb + b - Sqrt[amb (amb + 2 b)] is well-conditioned afaict
egg|afk|egg is now known as egg
<bofh>
and the leading term iirc is 1 so that means that 1-sqrt(1-x) is approximately x/2 for sufficiently small x. :P
<egg>
bofh: so as a function of a-b and b, this eggspression is well-conditioned
<bofh>
*nods*
<egg>
thus, how the hell do you evaluate amb + b - Sqrt[amb (amb + 2 b)] :D
<bofh>
(also brb, egglipse)
<egg>
bofh: have a fun egglipse
<egg>
also Fiora, PenumbralRaptor, et al.
<egg>
ferram4 and SnoopJeDi too probably
<PenumbralRaptor>
??
<SnoopJeDi>
raining and miserable in st joseph, but got to see the first 20% or so
<egg>
Cayley users will now get the Чебышёв reminder
<PenumbralRaptor>
And any at Oak Ridge will see the sun blotted out.
<egg>
eggsactly
<bofh>
troll question: how much energy would it take to change the inclination of the moon's orbit to match that of the ecliptic?
<PenumbralRaptor>
troll answer: 0 J
<bofh>
errrm, pretty sure it's inclined ~5.14deg relative to that, which is why we don't get total solar eclipses every month >_>
<bofh>
egglipses, even.
<PenumbralRaptor>
Yes, but v²/2-μ/r (or, -μ/2a) would be unchanged. Hence the troll answer.
<egg>
bofh: yes, but surely there is no lower bound on the energy required to get that inclination change in a chaotic system, so PenumbralRaptor is right :-p
<bofh>
touché
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<egg>
bofh: just fart in the general direction of the moon, and wait for the inclination change to happen
<bofh>
egg: pretty sure that'll take a lot of farting
<egg>
(warning: small Ляпунов times not guaranteed)
<kmath>
<whitequark> nothing like returning to my dwelling and realizing it has been taken over by the most vile, disgusting colony of mold i have ever seen
<bofh>
Can't you factor that into Sqrt[x]Sqrt[2b+x]? :P
<egg>
bofh: yeah but the subtraction
<egg>
(also wait, why would you even want to factor that?)
<bofh>
(for potential further simplification, mostly. otherwise no reason)
<bofh>
also that subtraction, actually that whole expression is vile
<egg>
bofh: yeah, but it's actually well-conditioned for positive arguments afaict?
<kmath>
<whitequark> @FioraAeterna @oshepherd @hikari_no_yume [✔] never having to vacuum ever again [✔] never having trouble removing bl… https://t.co/aMBG7dyswy
<UmbralRaptor>
What are you doing that causes blood stains?
<whitequark>
accidentally stabbing myself with glass
<whitequark>
printer sometimes menstruates
<Fiora>
reminds me i'm actually impressed i've managed to avoid blood stains on things given that my nose is extruding a rather red liquid this past week
<whitequark>
see, useful
<whitequark>
another thing you can do with LDPE fiber based pillows: got blood deep inside it? just dunk it into a barrel of 37% hydrogen peroxide you have
<whitequark>
that you bought on discount from rushim.ru at 17 RUB/liter, of course
<whitequark>
that's right next to my dream of having a foodglassware set made from quartz glass, so that I can replace dishwashing with waving it over an oxyacetylene torch for a bit
<whitequark>
I even found a glassblower that works with quartz
<UmbralRaptor>
Fiora: destroyed a sweatshirt once that way. >_>
* UmbralRaptor
would be concerned about getting chunks of "charcoal" stuck to the glassware.
<Fiora>
i may consider at some point seeing if they can cauterize my nose or something because i'm fairly sure i lose a very unresaonable amount of blood that way
<whitequark>
UmbralRaptor: okay new plan: piranha solution
<whitequark>
*hot* piranha solution.
<UmbralRaptor>
Fun fact: allergies can totally cause nosebleeds.
<whitequark>
made using the barrel of 37% hydrogen peroxide you have on discount from rushim.ru
<UmbralRaptor>
hah
<whitequark>
this is actually really troublesome because sulfuric acid is scheduled
<Fiora>
UmbralRaptor: oh yeah, i just mean my nose mostly never stops bleeding
<Fiora>
well, i mean, like, it takes breaks
<bofh>
UmbralRaptor: I was about to ask actually if allergies can do that since yeah.
<bofh>
22:34 <@whitequark> that's right next to my dream of having a foodglassware set made from quartz glass, so that I can replace dishwashing with waving it over an
<bofh>
oxyacetylene torch for a bit
<UmbralRaptor>
bofh: unfortunately this is personal xp, so I can't link a paper.
<bofh>
this is such a good idea
<whitequark>
bofh: I know right
<UmbralRaptor>
Fiora: eek
<whitequark>
do you want contact # of the glassblower
<bofh>
whitequark: tbh, yes
<Fiora>
UmbralRaptor: i mean it doesn't bother me really. like. unless it's flowing it's kinda just like another ingredient in mucus, right?
<Fiora>
it means i can turn tissues red on demand
<Fiora>
it's like water into wine but a whole lot less impressive
<whitequark>
lol
<UmbralRaptor>
Ah, the thin kind like I sometimes get in deserts, not a literal drip drip drip?