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.
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<SimulatedRaptor>
Well, near IR is disappointing from a photon noise perspective.
SimulatedRaptor is now known as UmbralRaptor
<UmbralRaptor>
Photon noise in the 900-2400 nm range seems to be >3x that of the 380-900 nm range.
<bofh>
I mean near IR is honestly a shoddy band to be observing long-range in, tbh.
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<UmbralRaptor>
bofh: Well, this is on a mountaintop, looking at least π/6 radians above the horizon.
<UmbralRaptor>
And blue/UV absorption and scattering is, uh, scary.
<bofh>
blue/UV absorption and scattering is nice and mathematically simple tbh.
<UmbralRaptor>
bofh: from an experimentalist's perspective, not a theorist's. An optical depth of > 0.5 at the Ca H and K lines is, uh, not fun.
<bofh>
UmbralRaptor: fair enough
<egg|phone|egg>
喵
<egg>
!wpn bofh
* Qboid
gives bofh an ultraviolet cabbage
<egg>
!wpn UmbralRaptor
* Qboid
gives UmbralRaptor a positive Durandal
<egg>
!wpn rqou
* Qboid
gives rqou a delta voulge/puffer train hybrid
<bofh>
Lyman βrassica? :P
<UmbralRaptor>
wait, Qboid gave me a real weapon.
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<Ellied>
UmbralRaptor: maybe move the text about the time periods a little closer? there's a lot of blank space and I didn't see the bottom one at first because lol 1366x768
<kmath>
<jradavenport> Last week @brettmor and I had the epiphany that @sdssurveys Stripe82 overlaps with part of @NASAKepler K2.... leadi… https://t.co/cRq1t3IGrL
<egg>
UmbralRaptor: when flying with big eyepieces (31,75 mm diametre naglers), should I put them in checked-in luggage or carry-on
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<kmath>
<mirihawke> .@FioraAeterna , talking about cosplay: Clearly I need to drop by Chromatic and borrow the propane torch. Me: NO I… https://t.co/bhVifWvQ7L
<egg|work|egg>
!wpn Fiora
* Qboid
gives Fiora a cathedral macrolanguage
<egg|work|egg>
!wpn whitequark
* Qboid
gives whitequark a spherical snake
<whitequark>
!wpn egg
* Qboid
gives egg an interferometer
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<egg|work|egg>
whitequark: how are the cats?
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<whitequark>
the dumb cat is very aggressive
<whitequark>
and is constantly harassing котя
<whitequark>
for no reason whatsoever
<egg|work|egg>
:-/
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<APlayer>
Hi!
<APlayer>
So... I've just had a rather weird experience. On my bus drive home, some stranger who was sitting close by (not uncomfortably close, though, he did not sit right next to me) just started a random conversation. Not on some occasion, just randomly started talking about... Well, about pretty much everything.
<APlayer>
Is some sort of compulsive conversation disorder a thing?
<APlayer>
It did not feel as harassment of any sort, really just weird, and I've been wondering if this could be a mental disorder
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<whitequark>
what
<whitequark>
why would it be a disorder
<whitequark>
people can be just lonely you know
<SnoopJeDi>
yea there are conversational psychological spectra but it's not necessarily reasonable to jump straight to those
<APlayer>
This was not normal... He first started describing how he never saw a person such as myself that could not be assigned to a nationality by their looks, continued to say that he hiself looks European, stuff here, stuff there, where he bought his hat, that he bought another one but he liked that one better
<APlayer>
And never stopped talking for more than about ten seconds
<Ellied>
petition to term matrix multiplication "heavy multiplication"
<UmbralRaptor>
APlayer: qboid's weapons are just randomly picking weapons and adjectives.
<Ellied>
!u ⏻
<Qboid>
U+23FB POWER SYMBOL (⏻)
<Ellied>
!u ⏼
<Qboid>
U+23FC POWER ON-OFF SYMBOL (⏼)
* UmbralRaptor
? ? in the fonts.
<APlayer>
Ah, okay
<Ellied>
my laptop doesn't show those either, even with otherwise-functioning Noto coverage
<Ellied>
APlayer: AIUI the algorithm Qboid uses to generate weapons is still the one I wrote years ago. It basically just rolls a few dice to pick from a few different formats and then fills them in with random adjectives or weapons
<egg|work|egg>
the greening weapon algorithm
<Ellied>
huh, why does unicode have the same character three times?
<kmath>
<MicroSFF> "Sabre-toothed cats weren't cats." "No? I have a time machine, wanna check?" * * * "OK, that's a cat. Now, how do we get it out of the box?"
<SnoopJeDi>
hehe
* egg|work|egg
pets the sabre-toothed kitty
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<APlayer>
So, relativity says no matter what your velocity is, any light will have a relative velocity of exactly 1 c.
<APlayer>
What happens to two photons that travel parallel to each other, then?
<Ellied>
APlayer: photons travel at c, so their gamma factor is infinite and they experience zero time
<Ellied>
so the other photon can be argued to still be travelling at c relative to the first if you like, it will just never actually move because photons don't experience time
<APlayer>
Alright, so this works with anything that moves at any speed relative to a parallel photon?
<APlayer>
Well, no, not any speed relative to a photon, any speed relative to some outside observer
<Ellied>
yes, although what I just said was very misleading because infinite gamma factor also implies infinite length contraction, so photons not only don't experience time, they arguably don't experience *space*. In a photon's hypothetical reference frame, the thing that emitted it and the thing it collides with (in our reference frame possibly millions of light-years apart) are in the same exact
<Ellied>
position
<APlayer>
Got it
<Ellied>
My favorite way of visualizing the whole "same c in all frames" thing is to imagine a cannon that fires a tube at close to the speed of light and a photon through the middle of the tube
<Ellied>
in the ground reference frame, the photon will take a while to traverse the length of the tube, since the photon and the tube are at almost the same speed
<APlayer>
The tube gets shorter for the photon?
<APlayer>
That is, like zero-length shorter
<Ellied>
in the tube's reference frame, the photon crosses the tube very fast, because the speed of light relative to the tube is the same, except time passes more slowly for the tube and the universe contracts in the direction it moves, so it still sees itself traverse the same distance as the ground frame does in the time it takes the photon to traverse it
* APlayer
imagines Einstein shaking his index finger at a class: "And remember, Kids, don't make massive objects travel at the speed of light!"
<APlayer>
Things seem to break down a lot more than immediately obvious when something travels at 1 c
<Ellied>
so if the tube is one nanosecond long (one foot, thereabout) and is travelling at 0.999999999c in the ground's reference frame, then the ground sees the photon take one second to traverse the tube, while the tube sees it take one nanosecond
<APlayer>
LOL I guess by the point such a cannon has fired, the ground does not see anything anymore
<APlayer>
J/K, good visualization
<APlayer>
Seems like a good way to put the things together once you know them
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<Ellied>
you have to have a lot of suspension of disbelief to think about observations between reference frames in SR, lol. "wait, how do I see something that's going past me at close to the speed of light"
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* UmbralRaptor
gives egg|phone|egg a train with a several digit Lorentz factor.
<Ellied>
It's not very intuitive at first, but once you're willing to take the founding principles as givens, it only takes a few cumulative hours of pondering to see how they fit together
<APlayer>
Not sure I have a few cumulative hours of pondering
<Ellied>
I think that makes it the coolest thing I've ever studied by far, honestly
<Ellied>
oh, is this for a homework assignment? :P
<APlayer>
But I guess I am slowly arriving at the point where I can intuitively understand how relativistic movement works... Not /quite/ there, but close
<APlayer>
Also, no. I wish we did do such things in physics class, but alas
<APlayer>
Third time circling around electric and magnetic fields now, IIRC
<UmbralRaptor>
I'm tempted to dig up an old flash game (velocity raptor) because it deals with SR to some degree,
<APlayer>
There was this open source game that made you do something while shortening the speed of light down to walking pace
<APlayer>
Don't remember any details, but looked rather cool
<APlayer>
Including doppler effect and all the goodies you'd want to see
<UmbralRaptor>
A Slower Speed of Light?
<APlayer>
Looks like that's it, yes
<APlayer>
"the searchlight effect (increased brightness in the direction of travel)" How does that work?
<soundnfury>
!wpn -add:adj reference-counted
<Qboid>
soundnfury: Adjective added!
<Ellied>
also velocity raptor!
<Ellied>
I think velocity raptor does a better job of teaching honestly, but it's not as pretty
<Ellied>
as ASSOL that is
<Ellied>
oh you mentioned that already of course
* Ellied
needs to read more than the last three lines when coming back
<Ellied>
I show all my friends Velocity Raptor when they take SR in the modern physics class, they all love it
<UmbralRaptor>
\o/
<Ellied>
weird thing I saw yesterday: Irish Heritage Center in Chicago has a dish antenna on its roof, apparently aimed at another dish antenna on a tower (its own tower) in the distance. Looks like a point-to-point link, I just can't imagine what for.
<egg>
<egg> UmbralRaptor: when flying with big eyepieces (31,75 mm diametre naglers), should I put them in checked-in luggage or carry-on
* egg
going to ANBO tomorrow
<UmbralRaptor>
egg: I'd default to putting fragile and/or expensive things in carry-on.
<egg>
UmbralRaptor: I'm more wondering about whether it might be considered suspicious and thus be manipulated by people than mechanical shocks (small objects in the middle of a lot of socks are generally fine)
<bofh>
egg: yeah that's def. a microwave point-to-point link.
<bofh>
err
<bofh>
Ellied
<egg>
bofh: are you telling me I should put a point-to-point link in my suitcase
<bofh>
my guess is it's a TV program backhaul to the transmitter tower.
<Ellied>
backhaul?
<bofh>
Ellied: so stuff is typically recorded in a studio and then sent via backhaul to the high-power transmitter tower. these two are virtually never in the same location, as towers need to be tall and emit strong RF.
<UmbralRaptor>
egg: yes. Do you know where your high gain antenna is?
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<UmbralRaptor>
Uh, IIRC, lots of checked luggage has people going through it.
<Ellied>
ohh, so the distant tower is a TV broadcast antenna with a point-to-point receiver for the data it retransmits?
<bofh>
Ellied: for radio the backhauls in North America are generally narrow-band FM in the 400MHz-500MHz range (and often include stuff that is meant to be processed, not just live content, so it's fun to listen in on them)
<Ellied>
neat
<bofh>
Ellied: for TV that won't work, so backhauls are either microwave point-to-point or IP.
<bofh>
so yeah, honestly that's my most likely *guess*. but don't quote me on it, it could be anything.
<Ellied>
My first thought was internet, but that seems like a strange way to do that in a city with so much cable infrastructure close at hand
<APlayer>
"We can't offer routers, but we have WiFi transmitted via high-gain antennae!"
<APlayer>
Also good for cooking your dinner in case of emergency
<APlayer>
And you can literally say the internet cooked for you today
<Ellied>
well, expecting a microwave data link to cook food because a microwave oven does that with the same kind of wave is roughly the same as expecting a single LED to light up your whole house because the sun does that with the same kind of wave :P
<APlayer>
Ramp up the power and boom! You have a directional microwave
<Ellied>
microwave ovens also have to get standing waves going inside an appropriately-sized resonant cavity to get anywhere, but presumably you can "just" connect the receiver feedline to such a metal box
<APlayer>
Do they indeed need standing waves? Isn't that more like an efficiency thing?
<Ellied>
I think you'd be hard-pressed to create a strong enough electric field to get water molecules to spin like that without resonance.
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<APlayer>
Alright
<Ellied>
I think if you ran the microwave with the door open (even slightly ajar) then it would hardly work at all to heat food
<APlayer>
Would another dish bouncing back the microwaves work as a replacement?
<Ellied>
in theory, sure, but I think you'd have a lot of loss
<Ellied>
ultimately I suspect it's always going to come back to "what if we tried more power?" and you can *always* cook things if you keep doing that for long enough.
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* UmbralRaptor
grabs a guillotine.
<APlayer>
So, I've seen a great deal of weird stuff in the short time I have already lived, but putting an egg into a guillotine is fully and completely new to me
<SnoopJeDi>
I'm reading "Galois ray" and I just can't stop thinking about Galois's fatal duel
<SnoopJeDi>
One of Galois's biographers did a short (<30min) film about him! I've not watched it though, because I couldn't find a copy with adequate subtitles
<kmath>
<random_addendum> Circuit board cookies embossed using a laser engraved rolling pin. :D https://t.co/faEApTpj8L
<SnoopJeDi>
sure hope so
<Ellied>
huh, so pressing the HP help key (normally fn-f1, but fn keys are enabled by default on the f-keys) just types P in the terminal
<Ellied>
I mean I think that's P
<Ellied>
!u P
<Qboid>
U+0050 LATIN CAPITAL LETTER P (P)
<Ellied>
yup
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<egg>
UmbralRaptor: bofh: We should do TRAPPIST-1 https://forum.kerbalspaceprogram.com/index.php?/topic/162200-wip122-131-principia%E2%80%94version-christoffel-released-2017-12-18%E2%80%94n-body-and-extended-body-gravitation-axial-tilt/&page=36&tab=comments#comment-3247785
<egg>
UmbralRaptor: also, 古在
<UmbralRaptor>
Hm
* UmbralRaptor
stares at Quals, why his QM registration vanished, and research.
* UmbralRaptor
feels anxious.
<SnoopJeDi>
"And if you gaze long into the research, the research also gazes into you."
<UmbralRaptor>
Is my research going to apply for a grant to study me?
<SnoopJeDi>
;8
<SnoopJeDi>
err
<SnoopJeDi>
;8ball
<SnoopJeDi>
you get the idea
<SnoopJeDi>
!wpn kmath
* Qboid
gives kmath a hypothetical NaN
<awang>
Quantum mechanics registration?
<UmbralRaptor>
I was checking my grades, an it's missing.
<UmbralRaptor>
*and
<SnoopJeDi>
registration for next semester, or grade for a past one?
<egg>
problem is it effectively requires replicating the work done by the authors, to get initial conditions that fit the observations (mean elements are useless)
<bofh>
wait, why are mean elements necessarily useless?
<bofh>
if we can get expressions for Mean Anomaly as a function of time that are good, that should be enough to get accurate apsides, at the minimum
<UmbralRaptor>
Ow, faux Cyrillic using real characters.
<egg>
bofh: mean elements in the sense of not-osculating (e.g. this planet has an observed period of 1.618 days) are hard to turn into initial conditions
<bofh>
okay, true. also that's crazy short for an orbital period