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comment by Devac

Here's an IRC log from about an hour ago:

18:57 < Devac> I'm mostly fine. looking for a good topic for Partial Differential Equations

18:58 < keifer> Sounds above my head. basic usage of Haskell is about as far as my math abilities go.

…

19:00 < Devac> well, it basically boils down to eliminating options that are either a) some boring proof, b) some shitty standard problem with a tweak

I think that you just gave me an inspiration for my project. Believe it or not, I'm serious and only slightly sleep-deprived.

What about the Van Allen radiation belts? I mean, that's a constant bombardment of the building/tether with some quite nasty particles alongside all the craziness related to the presence of plasma. Not to even mention currents that would be induced in this megastructure.




am_Unition  ·  595 days ago  ·  link  ·  

Woohoo! Only slightly sleep-deprived? I'm not going to post my sleep schedule, I will be chastised. And I'm a big boy, so I do my own scolding these days.

We're possibly entering another grand solar minimum. Very little storming/spots, the previous sunspot cycle was a dud, but it's almost over. No one really knows what happens next. Either way, we have been steadily putting more and more satellites up there, and another major coronal mass ejection event could happen any day, even when the sun's looking chill. We know space weather, but not space climate. If we have another Carrington Event sometime soon, I'm worried somebody will think somebody else has plans to use the opportunity for a nuclear strike, and go on the defensive (read: offensive). Regardless of whatever chain of events it sets in motion, we have the potential to see tens to hundreds of billion$ in damaged satellites. Yessir.

Geo is in the outer rad belt, true, but the outer belt is electrons, and the stopping power of several MeV electrons isn't so bad. You could (and probably would) have people living on the thing, underground, but not many, and they should have an evacuation plan that takes less than a day to execute, in the event of a "serious enough" storm. You could kinda control the asteroid's potential, if you needed to, with the ion thrusters, and you could shield the most sensitive electronics using the asteroid's surface geometry (and going sub-surface). As for induced currents from geomagnetic storming, I think you could design for it, but there's no need to run the thing during the rare storm. Strong currents from storming most intensely affect systems above a certain scale size (as I'm sure you know). Cosmic ray degredation of circuitry edit: and people :( might be the biggest problem, no atmosphere. No cosmic showers! Probably not many showers on that hunk of rock at all.

Here's another space-y idea for you to check out: Ballpark estimate how energy would have to be dumped into the Earth's atmosphere (over some span of time) to de-orbit the Iridium satellite constellation (via enhanced drag from more collisions cuz higher density) in a period of 2 hours? In a period of 8 hours? You can assume homogeneous heating of the atmosphere and equilibrium with a magical heating element that we're distributing evenly across all of the atmospheric particles, so still a maxwellian distribution (in the thermosphere). Edit2: I'm thinking it's not exactly maxwellian up there, but whatever, justify some boost in the distribution function/shape. You'll need a couple/few other simplifying assumptions, probably. I think in reality, heating would be quite localized to the auroral regions, and the Iridium satellites are in polar orbit, so they do pass through there. Actually, people get magnetometer data from those guys, AMPERE, and nobody tells anybody else about much of this cool stuff, because I dunno.

This is now a space thread.

Devac  ·  595 days ago  ·  link  ·  

Perhaps I should have specified that bit about electron bombardment: it changes the hardness of bombarded material for the electrons in the energy range we are talking about. Structure and hardness of materials after electron bombardment is one of the studies about it. This can introduce a steady change in hardness that will differ depending on the height, changing how the vibrations and oscillations are distributed in the long term. Even if it's just the outermost layer, I have a weird suspicion that it would lead to the shedding of the hardened material with time in uneven rates over the structure's profile. Perhaps I'm overthinking the material science part of it, especially considering kleinbl00's post, but there's a good reason why mechanical engineering puts so much emphasis on wear and tear of materials.

About the estimation… I'll get to it after homework :P. After two weeks of very light assignments, I'm getting swamped with projects that require some independent research.

am_Unition  ·  594 days ago  ·  link  ·  

    I'm getting swamped with projects that require some independent research.

Instead of going to class and turning in my homework, I went to bed. I'm fucking done for the week, dude.

Edit: "Fourier transform the Coulomb potential into 6D k-space and back again." It's not even hard! It's just fucking follow math rules, Wo0o0OO0o0, wow, that's teaching people how to think! Let's pretend everyone's a calculator! Go get fucked. How can anyone wonder why there's a lack of creativity among scientists when we're basically jamming fist fulls of punchcards down their throats since they said "ma-ma". No one's well-rounded anymore. The expertise required to achieve any coveted status in a globalized world of 8 billion stamps out generalists.

Devac  ·  594 days ago  ·  link  ·  

    "Fourier transform the Coulomb potential into 6D k-space and back again."

I'm guessing that this is a larger rant brewing, but are you doing some sort of symplectic phase space calculations or is it about quantization of potential in general? In either case, this paper by Maurice de Gosson and this overview of applications of symplectic spaces helped me a lot with getting some sense out of it. At least for a given definition of sense and keeping in mind that I'm one of those maths-kids that you seem to be so annoyed with. ;)

But I agree. Most of my physics courses are largely maths courses put in a context of differently worded axioms. When the least abstract thing I have this semester is the formal treatment of diffraction I begin to see why so few people remain on physics.

am_Unition  ·  594 days ago  ·  link  ·  

It's a kinetic plasma theory course. We're taking a two or one-fluid plasma phase space distribution function into fourier space for dispersion relations, and laplace transforms to get into Fokker-Planck diffusion treatments. It's more than a little cool, it's just not the sort of thing you only have 10 hours to budget for every other week because you're spending most of your time teasing out electron motions near the diffusion region of magnetic reconnection.

Every class here starts like "OK, so when we subtract two vectors..." and then two months later it's "...arriving, of course, at the Christoffel symbols, a rank X tensor containing the coefficients of fictitious forces arising form coordinate transformations".

My academic situation is rapidly deteriorating, yes. Someday maybe you'll read about it in a book! ...written by my future child for a fourth grade literature project.

Thanks for listening by the way. I've not truly been myself for months, now. I'm leaving this place soon, American universities are becoming a generally toxic environment. I think there are 3 to 4 "administrators" for each professor, and we're still wondering where the grant money is going? Trump's going to bleed them dry, if he has his way. Big brain drain over the next few years.

Devac  ·  594 days ago  ·  link  ·  

    It's a kinetic plasma theory course. We're taking a two or one-fluid plasma phase space distribution function into fourier space for dispersion relations, and laplace transforms to get into Fokker-Planck diffusion treatments.

Woosh!

I can kinda see how all that would connect, but that's it. I might as well tell you to "do a barrel roll".

    Every class here starts like "OK, so when we subtract two vectors..." and then two months later it's "...arriving, of course, at the Christoffel symbols, a rank X tensor containing the coefficients of fictitious forces arising form coordinate transformations".

It hits close to home. My GR course this semester started with "this is your typical gravitational potential, nothing fancy". It's nothing like that since week three.

    Thanks for listening by the way.

Come on, man. That's the least I could do, especially considering the walls of text that I'm usually dumping on you. I hope you'll get some break soon. And not the psychotic kind, just a normal leisurely type of break.