egg|nomz|egg 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> egg|nomz|egg: generally if your eyes are dewing over, that's not the weather. | <ferram4> I shall beat my problems to death with an engineer.
<UmbralRaptop>
Tofu here
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<bofh>
UmbralRaptop: also tofu
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<bofh>
lmao I just had some random RATP staffer do a triple take at me
<bofh>
I'm only sitting on a bench at my laptop reading Laplace's Mécanique Céleste while wearing a straw hat with VLC stickers on it,
<UmbralRaptop>
Perfectly normal
<bofh>
it's not even that late, like it's not even 3AM,
<UmbralRaptop>
Huh, Trujillo et al use MERCURY6 on 2015 TG387
<UmbralRaptop>
Quadrupole moment from the giant planets o_O
<SnoopJeDi>
oh jeez, I've *just* realized why the first line is obvious >_>
<SnoopJeDi>
I showed this to the person who recommended that I read Anathem and their response was "how did you get chapter 0 of The Book"
<bofh>
ROFL
<B787_300>
egg: what is that elestrial reference article about?
<B787_300>
is it the release of ICRF3?
<egg>
yeah
<egg>
B787_300: with a funny leap second remark at the beginning
<B787_300>
mas is milliarcsec right?
<egg>
yes
<egg>
B787_300: the first sentence is "on 31 dec. 2018 at midnight, we won't move our watches forward one second (unless the IERS forces us to by then...) but we will slightly move the axes of our fundamental celestial reference system"
<B787_300>
i wish the accuracy on the celestial sphere graphs were uploaded in full size
<B787_300>
good we cant just have the french geodessy sat in there
<bofh>
today in "bofh": I just wound up apologizing to a snail in broken French (I kicked its shell by accident thinking it was a rock, it seems okay).
<UmbralRaptop>
ow
<egg>
bofh: okay, but have you considered: eating the snail,
<egg>
B787_300: unfortunately Stella isn't an acronym afaic
<egg>
s/$/t/
<B787_300>
is escargot cooked?
<Qboid>
egg meant to say: B787_300: unfortunately Stella isn't an acronym afaict
<bofh>
What's the rate of incidence of Strongyloides stercoralis amongst random FR snails?
<bofh>
also Angiostrongylus cantonensis
<bofh>
for that matter
<bofh>
I suppose if you make sure they're *very* well-cooked you'll be fine (also it seems like it hasn't hit Europe yet according to wikipedia???)
<B787_300>
UmbralRaptop: do you think I should rent a car for this weekend or do you think ubering around would be fine (and what about costs)
<UmbralRaptop>
B787_300: I, er, haven't used Uber.
<B787_300>
...
<UmbralRaptop>
Road layouts + traffic is somewhat stressful, but my baseline is places like KC…
<SnoopJeDi>
There are estimation sites for Uber/Lyft FWIW
<UmbralRaptop>
Reston area should be fine for driving. If you're going into DC, parking is awful enough that I'd look into transit.
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<bofh>
win 56
<iximeow>
win 95
<iximeow>
(how do you heven have 56 windows)
<bofh>
iximeow: a lot of open PM windows, and a lot of channels I virtually never look at, lol.
<UmbralRaptop>
thermonuclear tabsplosion?
<SnoopJeDi>
yea DC is a car exclusion zone for sure. the upshot is that the Metro is great for getting into the city (if not necessarily around it)
<B787_300>
UmbralRaptop: yeah I'll be in reston pretty much all the time
<UmbralRaptop>
Bus + metro results in very long commutes, but that's acceptable for tourism purposes.
<SnoopJeDi>
Newseum is awesome btw :)
<B787_300>
SnoopJeDi: i would but i am going for a wedding and the only day i wont be doing wedding stuff is monday and i have never been to Udvar so i am going there
<kmath>
<bofh453> <@bofh453> goddamnit two random girls walked by talking about femtosecond laser physics and fuck I really wish I kn… https://t.co/r3PXZUQtRR
<bofh>
(I was at Cité Florale at the time)
<B787_300>
what is special about femtosecond laser that requires it own special physics
<UmbralRaptop>
Getting pulses that short is, uh, highly nontrivial. Something about getting 2 wavetrains to overlap just right?
<B787_300>
what is that at least a THz pulse rate?
<B787_300>
also what power levels are we talking here?
<UmbralRaptop>
at least, possibly PHz, and unsure.
<UmbralRaptop>
bofh?
<SnoopJeDi>
♫ You put your short pulse in / you get a long pulse out / you take your spread-out pulse / and you shake it all about / you do the hokey pokey and you amplify P_out / that's what it's all about ♫
<SnoopJeDi>
alternatively, "phase-space pokey" but eh
<B787_300>
just thinking that with that short of a pulse you could get silly accurate ranging measurements (if you had an accurate enough clock and detector)
<SnoopJeDi>
and your pulse doesn't get eaten!
<UmbralRaptop>
?!
<B787_300>
Yeah I am just as confused
<SnoopJeDi>
B787_300, you're talking about ranging at distance?
<SnoopJeDi>
IIRC the coherence length of such pulses is *very* short
<B787_300>
Yes. Ideally between 100km to oh about 40000 km
<B787_300>
I mean imagine the fun geodessy with super accurate orbit measurements
<UmbralRaptop>
Hrm. MOLA did 8 Hz, ICEsat will do 20 kHz
<SnoopJeDi>
coherence lengths here are something more like μm
<SnoopJeDi>
and even if they were long, I assume you'd dump your pulse energy into...something.
<SnoopJeDi>
which I guess is soooorta what you're getting at? but I think you'd get away with conventional lidar
<B787_300>
Doesn’t coherence only matter if you are trying to image? I though if you are just trying to get a return it doesn’t matter
<SnoopJeDi>
laser ranging to the lunar reflector array is what, fraction of a cm?
<SnoopJeDi>
granted that's a *long* collection time
<B787_300>
Don’t they time gate the returns so you don’t eat a false detection. I mean we know where the moon is so just open the shutter on the dectector a couple milli sex before earliest possible return
<B787_300>
Millisecs ^ damn autocorrect
<B787_300>
s/eat/get
<Qboid>
B787_300 meant to say: Don’t they time gate the returns so you don’t get a false detection. I mean we know where the moon is so just open the shutter on the dectector a couple milli sex before earliest possible return
<SnoopJeDi>
at any rate, I know ultrashort pulses in air are sufficiently good at generating all kinds of interesting nonlinear phenomena (one group here uses them to study the Kerr effect or maybe it's supercontinuum generation using that IIRC)
<SnoopJeDi>
but uh, optics people are wily so...maybe?
<SnoopJeDi>
cosmic brain: rangefinding by inducing backlasing in the target
<B787_300>
Wouldn’t that require the ablation of small amounts of material
<SnoopJeDi>
hmm, dunno! backlasing is usually pump/probe so maybe not
<SnoopJeDi>
I've only ever seen it for clouds of gas, hehe
<SnoopJeDi>
so maybe you have to first vaporize enough of the target to backlase :D
<SnoopJeDi>
which is alarmingly close to what ChemCam on MSL does...
<UmbralRaptop>
"It's a reference book. It's not a textbook. It's too short, it doesn't develop anything. The only value to this textbook is that it makes you learn very hard PDE and general vector calculus theory. But it doesn't teach it at all, it just holds you accountable for it."
<bofh>
B787_300: well, more the consequences OF that laser physics, specifically the conversation was about pump-probe spectroscopy
* B787_300
watches that fly over his head
<B787_300>
What is pump probe spectroscopy
<bofh>
basically take a laser, use one pulse to break a bond and another as a means of checking what state the relevant atom is in
<bofh>
varying the delay between the two as you need
<SnoopJeDi>
and a whole slew of tricks developed thereupon in the intervening ~30 years
<SnoopJeDi>
it's a bit like the invention of the scanning tunneling microscope (or the laser itself!) in that sense: it puts a new tool in the "optical toolbox"
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<egg>
!meow whitequark
* Qboid
meows at whitequark
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<egg|cell|egg>
!meow bofh
* Qboid
meows at bofh
<egg|cell|egg>
!meow whitequark
* Qboid
meows at whitequark
<egg|cell|egg>
!seen bofh
<Qboid>
egg|cell|egg: I last saw bofh on [03.10.2018 03:41:23] in #kspacademia saying: "varying the delay between the two as you need"
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* UmbralRaptop
🔪 viruses
<egg|work|egg>
whitequark: bofh: how do you say "I pet 1 million cats" in ru
<kmath>
<✔planet4589> The @ParkerSunProbe entered Venus' gravitational sphere at 2035 UTC Oct 2. Venus closest approach in a little unde… https://t.co/6xwe2oDOxF
<bofh>
like I'm still not sure I understand the point of Parker Solar Probe, but that's still cool as shit.
<bofh>
speaking of solar stuff I just grabbed ftp://sohoftp.nascom.nasa.gov/pub/www/freestuff/freestuff.html out of curiosity and the program required VBRUN300.DLL and holy crap that is a blast from the past.
<UmbralRaptop>
Something something solar wind something corona something space weather
* UmbralRaptop
could ask some of the heliophysics and space weather people on campus.
<bofh>
ugh. so yesterday my knee finally stopped being vaguely dodgy and then started hurting again after only about 6km of walking.
<bofh>
UmbralRaptop: could've sworn we already have several missions in the solar wind/corona region, so I'm a bit confused. should prolly just read some papers.
<UmbralRaptop>
Nothing anywhere near as close
<bofh>
basically my question boils down to "why do you need to fly *that* close to the outer corona to probe it? it's incredibly hot so couldn't you do it from a distance using various emission spectroscopies?"
<B787_300>
bofh: something something data degredations or chemical reactions / decays changing the composition?
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<UmbralRaptop>
My understanding is limited, but something about bringing in magnetometers and particle detectors?
<kmath>
<Steven_Banham> WOW ⏎ "The atmosphere of the newly melted Earth, composed of mostly rock vapor and silicate clouds, ... lasted throug… https://t.co/wEw0RORn2h
<kmath>
<cgranade> A lot of people are talking about sequels to MEAN GIRLS today, but it really felt to me like that film describes a… https://t.co/rf0z0rT6EA
<kmath>
<jaxsun> Whoa. New for-profit immigration prison report out, includes: "Floss is only available through detainee commissary… https://t.co/J0ncm4y8vg
<NomalRaptor>
I mean, that's the sort of weirdness you'd expect for the first detection.
NomalRaptor is now known as UmbralRaptor
<bofh>
UmbralRaptor: I mean, sure, it's more I'm amazed that's a thing that can even happen.
<UmbralRaptor>
Fair enough.
<UmbralRaptor>
Please don't ask me what the formation mechanism is.
<bofh>
I mean I wasn't eggspecting anyone to have an idea, honestly.
<iximeow>
that's no moon...
<UmbralRaptor>
"The blackbody equilibrium temperature of the planet and moon, assuming zero albedo, is ~350 K. Adopting a more realistic albedo can drop this down to ~300 K. Of course, as a likely gaseous pair of objects, there is not much prospect of habitability here, although it appears that the moon can indeed be in the temperature zone for optimistic definitions of the habitable zone."
<UmbralRaptor>
"The origins of such a system can only be speculated upon at this time. A mass ratio of 1.5% is certainly not unphysical from in situ formation using gas-starved disk models, but it does represent the very upper end of what numerical simulations form (40). In such a scenario, a separate explanation for the tilt would be required. Impacts between gaseous planets leading to captured moons are not well studied but could be wo
<bofh>
Hrm.
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<awang>
MSVC compiles that fine, but clang-cl does not
<awang>
Gah
<awang>
Compilers are allowed to pick the underlying type for enums however they please, right?
<awang>
Apparently Clang picks unsigned int as the underlying type for an enum value of 0x8000'0000, but picks regular int when --target=x86_64-windows-msvc is given and converts 0x8000'0000 to std::numeric_limits<int>::min()
<awang>
I'm not sure whether this should be considered a bug or not
<awang>
Are enum values allowed to be converted like that?