• Member Since 11th Jul, 2013
  • offline last seen 5 hours ago

AcademicPony


Writing Status

Active:
- Celemac Vignettes
- Time Loop Logic

Queued:
- LAN Party of the Night
- Gone Horribly Right

Mothballed:
- Evil Dead, Chainsaw Good
- Being Pinkie Pie
- Bad Idea Machines

Biography

I am an academic who encountered FiM in the fall of 2011 (having previously watched G1). It says something about me that after watching the "Starscream vs Rainbow Dash" video, I spent a week working out how you'd make pony-bots that could actually do that.

I don't write very often, but from time to time I may post a short work here. I've greatly enjoyed many other authors' works; you can find some of them in my favourites list.

I'm willing to help proofread/edit stories, if they catch my interest, but be warned that I'm old-fashioned enough to prefer to do this by marking up hardcopy and mailing it back to you.

From time to time, I may ask permission to make printed/bound versions of others' works. I make these out-of-pocket and distribute them for free (the idea of getting others addicted to ponyfics amuses me). Even with full permission, I do not want to touch electronic distribution or paid print runs. If you want to handle that for your story, though, I'll gladly provide the LaTeX source files and PDF output.

Let me stress again that I only distribute works after asking first (author and cover-artist, if any). Copyright is to be taken seriously.

(Avatar artwork by Miss-Kiki)

Jun
24th
2019

Update for June 2019 · 5:13pm June 24th

I've been mentoring a grad student on "de-scoping". It's time for me to do that here too:

- The markup on iisaw's older fic will get sent to him as-is, after my next visit to my old city (ink-on-paper markup is filed with old creative writing projects; I only brought active projects with me). I had problems with the direction the story went, and should have either finished the markup or bailed on it when that occurred instead of shelving it.

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Comments ( 11 )
  • Viewing 7 - 11 of 11

Thanks for adding How "My Little Pony: The Movie" Should Have Ended to your favorites! :)

2258806
Yes and no. Pretty much any situation that allows FTL in GR allows you to construct closed timelike curves, and pretty much any situation where you have one part of the universe moving FTL relative to another gives you a) an event horizon and b) a weird coordinate discontinuity at the horizon (at least from any single observer's point of view).

That last bit is actually the result of the way the observer's viewpoint is chosen, rather than reflecting a real discontinuity. Building coordinate grids is (usually) done by imagining space filled with fixed-length rods at rest with respect to the chosen viewpoint. Problems occur when the situation makes it impossible to have a distant point be at rest (such as when that distant point is on the other size of an event horizon). So, you get your coordinate system blowing up at the location where this occurs and becoming imaginary beyond it. The right way to solve this problem is to instead define coordinate systems that are valid within a local patch of space but don't try to cover all of it, and then walk around building a map of how those local coordinate frames relate to each other.

Closed timelike curves, while self-consistent within general relativity, cause enough problems elsewhere that a lot of scientists strongly suspect there's some rule or side effect that we don't know about that forbids them/makes it impossible to set up situations that would produce them. The same applies to negative mass and a number of other fun things. That said, nobody expects any new discovery of such a rule to invalidate relativity (any more than relativity invalidated electromagnetism or Newton's laws); it'll just add context instead.

2258734 That's less convincing than I'd expected. It seems to me more of a sign of a bug in the theory than a solution.

2258391
As for FTL motion in a rotating frame, that's actually been studied; what you get is a strange configuration of space where everything sufficiently far from the center forms "closed timelike curves" (time travel loops). Ye Wiki's article on one such situation is here.

2258391
The short answer is, because that results in a situation where you can no longer use the simple, cleanly-formulated forms for Newton's laws of motion and Einstein's laws of special relativity (I'd need to think about how GR would transform under those conditions).

The long answer is, with enough effort, you can make a mathematically equivalent situation. This is what we do when we set up the laws of motion in a rotating reference frame. That link also immediately tells you the problem with doing this: you go from having a paragraph of equations to having a full page of equations, which are more complicated and more difficult to use, and which don't give you any additional insight into the system you're making a model of.

Things get even worse when you're considering the interaction of two objects distant from you; in the conventional scheme, you can just pick a reference frame where the math is easiest without additional complexity (just adding or subtracting an appropriate amount from the position and velocity). So, you can analyze the orbits of the moons of Jupiter by picking a frame where Jupiter was the center of your coordinate system. With a geocentric frame that rotates with the Earth, you'd have a much hairier time. The page of math involved would give you something that amounted to transforming from your geocentric frame to the ordinary coordinate system, solving the laws of motion and gravitation there, and then transforming back... which makes using the geocentric frame in the first place pretty pointless (it gives you no new information and you have to bend over backwards to use it).

There are a handful of cases where using polar coordinates (rotation optional) does make life simpler and provide insights, but they're very carefully chosen, and are explicitly cases where you're throwing away details of a complex system in order to make it easier to analyze (deriving Kepler's laws and deriving where the Lagrange points are are the examples that come immediately to mind).

  • Viewing 7 - 11 of 11
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